Home | History | Annotate | Line # | Download | only in make
var.c revision 1.529
      1 /*	$NetBSD: var.c,v 1.529 2020/09/22 17:42:57 rillig Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1988, 1989, 1990, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Adam de Boor.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 /*
     36  * Copyright (c) 1989 by Berkeley Softworks
     37  * All rights reserved.
     38  *
     39  * This code is derived from software contributed to Berkeley by
     40  * Adam de Boor.
     41  *
     42  * Redistribution and use in source and binary forms, with or without
     43  * modification, are permitted provided that the following conditions
     44  * are met:
     45  * 1. Redistributions of source code must retain the above copyright
     46  *    notice, this list of conditions and the following disclaimer.
     47  * 2. Redistributions in binary form must reproduce the above copyright
     48  *    notice, this list of conditions and the following disclaimer in the
     49  *    documentation and/or other materials provided with the distribution.
     50  * 3. All advertising materials mentioning features or use of this software
     51  *    must display the following acknowledgement:
     52  *	This product includes software developed by the University of
     53  *	California, Berkeley and its contributors.
     54  * 4. Neither the name of the University nor the names of its contributors
     55  *    may be used to endorse or promote products derived from this software
     56  *    without specific prior written permission.
     57  *
     58  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     59  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     60  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     61  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     62  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     63  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     64  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     65  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     66  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     67  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     68  * SUCH DAMAGE.
     69  */
     70 
     71 /*-
     72  * var.c --
     73  *	Variable-handling functions
     74  *
     75  * Interface:
     76  *	Var_Set		    Set the value of a variable in the given
     77  *			    context. The variable is created if it doesn't
     78  *			    yet exist.
     79  *
     80  *	Var_Append	    Append more characters to an existing variable
     81  *			    in the given context. The variable needn't
     82  *			    exist already -- it will be created if it doesn't.
     83  *			    A space is placed between the old value and the
     84  *			    new one.
     85  *
     86  *	Var_Exists	    See if a variable exists.
     87  *
     88  *	Var_Value 	    Return the unexpanded value of a variable in a
     89  *			    context or NULL if the variable is undefined.
     90  *
     91  *	Var_Subst 	    Substitute either a single variable or all
     92  *			    variables in a string, using the given context.
     93  *
     94  *	Var_Parse 	    Parse a variable expansion from a string and
     95  *			    return the result and the number of characters
     96  *			    consumed.
     97  *
     98  *	Var_Delete	    Delete a variable in a context.
     99  *
    100  *	Var_Init  	    Initialize this module.
    101  *
    102  * Debugging:
    103  *	Var_Dump  	    Print out all variables defined in the given
    104  *			    context.
    105  *
    106  * XXX: There's a lot of duplication in these functions.
    107  */
    108 
    109 #include    <sys/stat.h>
    110 #ifndef NO_REGEX
    111 #include    <sys/types.h>
    112 #include    <regex.h>
    113 #endif
    114 #include    <inttypes.h>
    115 #include    <limits.h>
    116 #include    <time.h>
    117 
    118 #include    "make.h"
    119 #include    "dir.h"
    120 #include    "job.h"
    121 #include    "metachar.h"
    122 
    123 /*	"@(#)var.c	8.3 (Berkeley) 3/19/94" */
    124 MAKE_RCSID("$NetBSD: var.c,v 1.529 2020/09/22 17:42:57 rillig Exp $");
    125 
    126 #define VAR_DEBUG_IF(cond, fmt, ...)	\
    127     if (!(DEBUG(VAR) && (cond)))	\
    128 	(void) 0;			\
    129     else				\
    130 	fprintf(debug_file, fmt, __VA_ARGS__)
    131 
    132 #define VAR_DEBUG(fmt, ...) VAR_DEBUG_IF(TRUE, fmt, __VA_ARGS__)
    133 
    134 ENUM_FLAGS_RTTI_3(VarEvalFlags,
    135 		  VARE_UNDEFERR, VARE_WANTRES, VARE_ASSIGN);
    136 
    137 /*
    138  * This lets us tell if we have replaced the original environ
    139  * (which we cannot free).
    140  */
    141 char **savedEnv = NULL;
    142 
    143 /*
    144  * This is a harmless return value for Var_Parse that can be used by Var_Subst
    145  * to determine if there was an error in parsing -- easier than returning
    146  * a flag, as things outside this module don't give a hoot.
    147  */
    148 char var_Error[] = "";
    149 
    150 /*
    151  * Similar to var_Error, but returned when the 'VARE_UNDEFERR' flag for
    152  * Var_Parse is not set.
    153  *
    154  * Why not just use a constant? Well, GCC likes to condense identical string
    155  * instances...
    156  */
    157 static char varNoError[] = "";
    158 
    159 /*
    160  * Traditionally we consume $$ during := like any other expansion.
    161  * Other make's do not.
    162  * This knob allows controlling the behavior.
    163  * FALSE to consume $$ during := assignment.
    164  * TRUE to preserve $$ during := assignment.
    165  */
    166 #define SAVE_DOLLARS ".MAKE.SAVE_DOLLARS"
    167 static Boolean save_dollars = TRUE;
    168 
    169 /*
    170  * Internally, variables are contained in four different contexts.
    171  *	1) the environment. They cannot be changed. If an environment
    172  *	    variable is appended to, the result is placed in the global
    173  *	    context.
    174  *	2) the global context. Variables set in the Makefile are located in
    175  *	    the global context.
    176  *	3) the command-line context. All variables set on the command line
    177  *	   are placed in this context. They are UNALTERABLE once placed here.
    178  *	4) the local context. Each target has associated with it a context
    179  *	   list. On this list are located the structures describing such
    180  *	   local variables as $(@) and $(*)
    181  * The four contexts are searched in the reverse order from which they are
    182  * listed (but see checkEnvFirst).
    183  */
    184 GNode          *VAR_INTERNAL;	/* variables from make itself */
    185 GNode          *VAR_GLOBAL;	/* variables from the makefile */
    186 GNode          *VAR_CMD;	/* variables defined on the command-line */
    187 
    188 typedef enum {
    189     FIND_CMD		= 0x01,	/* look in VAR_CMD when searching */
    190     FIND_GLOBAL		= 0x02,	/* look in VAR_GLOBAL as well */
    191     FIND_ENV		= 0x04	/* look in the environment also */
    192 } VarFindFlags;
    193 
    194 typedef enum {
    195     /* The variable's value is currently being used by Var_Parse or Var_Subst.
    196      * This marker is used to avoid endless recursion. */
    197     VAR_IN_USE = 0x01,
    198     /* The variable comes from the environment.
    199      * These variables are not registered in any GNode, therefore they must
    200      * be freed as soon as they are not used anymore. */
    201     VAR_FROM_ENV = 0x02,
    202     /* The variable is exported to the environment, to be used by child
    203      * processes. */
    204     VAR_EXPORTED = 0x10,
    205     /* At the point where this variable was exported, it contained an
    206      * unresolved reference to another variable.  Before any child process is
    207      * started, it needs to be exported again, in the hope that the referenced
    208      * variable can then be resolved. */
    209     VAR_REEXPORT = 0x20,
    210     /* The variable came from command line. */
    211     VAR_FROM_CMD = 0x40,
    212     VAR_READONLY = 0x80
    213 } VarFlags;
    214 
    215 ENUM_FLAGS_RTTI_6(VarFlags,
    216 		  VAR_IN_USE, VAR_FROM_ENV,
    217 		  VAR_EXPORTED, VAR_REEXPORT, VAR_FROM_CMD, VAR_READONLY);
    218 
    219 typedef struct Var {
    220     char          *name;	/* the variable's name; it is allocated for
    221 				 * environment variables and aliased to the
    222 				 * Hash_Entry name for all other variables,
    223 				 * and thus must not be modified */
    224     Buffer	  val;		/* its value */
    225     VarFlags	  flags;    	/* miscellaneous status flags */
    226 } Var;
    227 
    228 /*
    229  * Exporting vars is expensive so skip it if we can
    230  */
    231 typedef enum {
    232     VAR_EXPORTED_NONE,
    233     VAR_EXPORTED_YES,
    234     VAR_EXPORTED_ALL
    235 } VarExportedMode;
    236 
    237 static VarExportedMode var_exportedVars = VAR_EXPORTED_NONE;
    238 
    239 typedef enum {
    240     /*
    241      * We pass this to Var_Export when doing the initial export
    242      * or after updating an exported var.
    243      */
    244     VAR_EXPORT_PARENT	= 0x01,
    245     /*
    246      * We pass this to Var_Export1 to tell it to leave the value alone.
    247      */
    248     VAR_EXPORT_LITERAL	= 0x02
    249 } VarExportFlags;
    250 
    251 /* Flags for pattern matching in the :S and :C modifiers */
    252 typedef enum {
    253     VARP_SUB_GLOBAL	= 0x01,	/* Apply substitution globally */
    254     VARP_SUB_ONE	= 0x02,	/* Apply substitution to one word */
    255     VARP_ANCHOR_START	= 0x04,	/* Match at start of word */
    256     VARP_ANCHOR_END	= 0x08	/* Match at end of word */
    257 } VarPatternFlags;
    258 
    259 /*-
    260  *-----------------------------------------------------------------------
    261  * VarFind --
    262  *	Find the given variable in the given context and any other contexts
    263  *	indicated.
    264  *
    265  * Input:
    266  *	name		name to find
    267  *	ctxt		context in which to find it
    268  *	flags		FIND_GLOBAL	look in VAR_GLOBAL as well
    269  *			FIND_CMD	look in VAR_CMD as well
    270  *			FIND_ENV	look in the environment as well
    271  *
    272  * Results:
    273  *	A pointer to the structure describing the desired variable or
    274  *	NULL if the variable does not exist.
    275  *-----------------------------------------------------------------------
    276  */
    277 static Var *
    278 VarFind(const char *name, GNode *ctxt, VarFindFlags flags)
    279 {
    280     Hash_Entry *var;
    281 
    282     /*
    283      * If the variable name begins with a '.', it could very well be one of
    284      * the local ones.  We check the name against all the local variables
    285      * and substitute the short version in for 'name' if it matches one of
    286      * them.
    287      */
    288     if (*name == '.' && ch_isupper(name[1])) {
    289 	switch (name[1]) {
    290 	case 'A':
    291 	    if (strcmp(name, ".ALLSRC") == 0)
    292 		name = ALLSRC;
    293 	    if (strcmp(name, ".ARCHIVE") == 0)
    294 		name = ARCHIVE;
    295 	    break;
    296 	case 'I':
    297 	    if (strcmp(name, ".IMPSRC") == 0)
    298 		name = IMPSRC;
    299 	    break;
    300 	case 'M':
    301 	    if (strcmp(name, ".MEMBER") == 0)
    302 		name = MEMBER;
    303 	    break;
    304 	case 'O':
    305 	    if (strcmp(name, ".OODATE") == 0)
    306 		name = OODATE;
    307 	    break;
    308 	case 'P':
    309 	    if (strcmp(name, ".PREFIX") == 0)
    310 		name = PREFIX;
    311 	    break;
    312 	case 'S':
    313 	    if (strcmp(name, ".SHELL") == 0 ) {
    314 		if (!shellPath)
    315 		    Shell_Init();
    316 	    }
    317 	    break;
    318 	case 'T':
    319 	    if (strcmp(name, ".TARGET") == 0)
    320 		name = TARGET;
    321 	    break;
    322 	}
    323     }
    324 
    325 #ifdef notyet
    326     /* for compatibility with gmake */
    327     if (name[0] == '^' && name[1] == '\0')
    328 	name = ALLSRC;
    329 #endif
    330 
    331     /*
    332      * First look for the variable in the given context. If it's not there,
    333      * look for it in VAR_CMD, VAR_GLOBAL and the environment, in that order,
    334      * depending on the FIND_* flags in 'flags'
    335      */
    336     var = Hash_FindEntry(&ctxt->context, name);
    337 
    338     if (var == NULL && (flags & FIND_CMD) && ctxt != VAR_CMD)
    339 	var = Hash_FindEntry(&VAR_CMD->context, name);
    340 
    341     if (!checkEnvFirst && var == NULL && (flags & FIND_GLOBAL) &&
    342 	ctxt != VAR_GLOBAL)
    343     {
    344 	var = Hash_FindEntry(&VAR_GLOBAL->context, name);
    345 	if (var == NULL && ctxt != VAR_INTERNAL) {
    346 	    /* VAR_INTERNAL is subordinate to VAR_GLOBAL */
    347 	    var = Hash_FindEntry(&VAR_INTERNAL->context, name);
    348 	}
    349     }
    350 
    351     if (var == NULL && (flags & FIND_ENV)) {
    352 	char *env;
    353 
    354 	if ((env = getenv(name)) != NULL) {
    355 	    Var *v = bmake_malloc(sizeof(Var));
    356 	    size_t len;
    357 	    v->name = bmake_strdup(name);
    358 
    359 	    len = strlen(env);
    360 	    Buf_Init(&v->val, len + 1);
    361 	    Buf_AddBytes(&v->val, env, len);
    362 
    363 	    v->flags = VAR_FROM_ENV;
    364 	    return v;
    365 	}
    366 
    367 	if (checkEnvFirst && (flags & FIND_GLOBAL) && ctxt != VAR_GLOBAL) {
    368 	    var = Hash_FindEntry(&VAR_GLOBAL->context, name);
    369 	    if (var == NULL && ctxt != VAR_INTERNAL)
    370 		var = Hash_FindEntry(&VAR_INTERNAL->context, name);
    371 	    if (var == NULL)
    372 		return NULL;
    373 	    else
    374 		return (Var *)Hash_GetValue(var);
    375 	}
    376 
    377 	return NULL;
    378     }
    379 
    380     if (var == NULL)
    381 	return NULL;
    382     else
    383 	return (Var *)Hash_GetValue(var);
    384 }
    385 
    386 /*-
    387  *-----------------------------------------------------------------------
    388  * VarFreeEnv  --
    389  *	If the variable is an environment variable, free it
    390  *
    391  * Input:
    392  *	v		the variable
    393  *	destroy		true if the value buffer should be destroyed.
    394  *
    395  * Results:
    396  *	TRUE if it is an environment variable, FALSE otherwise.
    397  *-----------------------------------------------------------------------
    398  */
    399 static Boolean
    400 VarFreeEnv(Var *v, Boolean destroy)
    401 {
    402     if (!(v->flags & VAR_FROM_ENV))
    403 	return FALSE;
    404     free(v->name);
    405     Buf_Destroy(&v->val, destroy);
    406     free(v);
    407     return TRUE;
    408 }
    409 
    410 /* Add a new variable of the given name and value to the given context.
    411  * The name and val arguments are duplicated so they may safely be freed. */
    412 static void
    413 VarAdd(const char *name, const char *val, GNode *ctxt, VarSet_Flags flags)
    414 {
    415     Var *v = bmake_malloc(sizeof(Var));
    416     size_t len = strlen(val);
    417     Hash_Entry *he;
    418 
    419     Buf_Init(&v->val, len + 1);
    420     Buf_AddBytes(&v->val, val, len);
    421 
    422     v->flags = 0;
    423     if (flags & VAR_SET_READONLY)
    424 	v->flags |= VAR_READONLY;
    425 
    426     he = Hash_CreateEntry(&ctxt->context, name, NULL);
    427     Hash_SetValue(he, v);
    428     v->name = he->name;
    429     VAR_DEBUG_IF(!(ctxt->flags & INTERNAL),
    430 		 "%s:%s = %s\n", ctxt->name, name, val);
    431 }
    432 
    433 /* Remove a variable from a context, freeing the Var structure as well. */
    434 void
    435 Var_Delete(const char *name, GNode *ctxt)
    436 {
    437     char *name_freeIt = NULL;
    438     Hash_Entry *he;
    439 
    440     if (strchr(name, '$') != NULL)
    441 	name = name_freeIt = Var_Subst(name, VAR_GLOBAL, VARE_WANTRES);
    442     he = Hash_FindEntry(&ctxt->context, name);
    443     VAR_DEBUG("%s:delete %s%s\n",
    444 	      ctxt->name, name, he != NULL ? "" : " (not found)");
    445     free(name_freeIt);
    446 
    447     if (he != NULL) {
    448 	Var *v = (Var *)Hash_GetValue(he);
    449 	if (v->flags & VAR_EXPORTED)
    450 	    unsetenv(v->name);
    451 	if (strcmp(v->name, MAKE_EXPORTED) == 0)
    452 	    var_exportedVars = VAR_EXPORTED_NONE;
    453 	if (v->name != he->name)
    454 	    free(v->name);
    455 	Hash_DeleteEntry(&ctxt->context, he);
    456 	Buf_Destroy(&v->val, TRUE);
    457 	free(v);
    458     }
    459 }
    460 
    461 
    462 /*
    463  * Export a single variable.
    464  * We ignore make internal variables (those which start with '.').
    465  * Also we jump through some hoops to avoid calling setenv
    466  * more than necessary since it can leak.
    467  * We only manipulate flags of vars if 'parent' is set.
    468  */
    469 static Boolean
    470 Var_Export1(const char *name, VarExportFlags flags)
    471 {
    472     VarExportFlags parent = flags & VAR_EXPORT_PARENT;
    473     Var *v;
    474     char *val;
    475 
    476     if (name[0] == '.')
    477 	return FALSE;		/* skip internals */
    478     if (name[1] == '\0') {
    479 	/*
    480 	 * A single char.
    481 	 * If it is one of the vars that should only appear in
    482 	 * local context, skip it, else we can get Var_Subst
    483 	 * into a loop.
    484 	 */
    485 	switch (name[0]) {
    486 	case '@':
    487 	case '%':
    488 	case '*':
    489 	case '!':
    490 	    return FALSE;
    491 	}
    492     }
    493 
    494     v = VarFind(name, VAR_GLOBAL, 0);
    495     if (v == NULL)
    496 	return FALSE;
    497 
    498     if (!parent && (v->flags & VAR_EXPORTED) && !(v->flags & VAR_REEXPORT))
    499 	return FALSE;		/* nothing to do */
    500 
    501     val = Buf_GetAll(&v->val, NULL);
    502     if (!(flags & VAR_EXPORT_LITERAL) && strchr(val, '$') != NULL) {
    503 	char *expr;
    504 
    505 	if (parent) {
    506 	    /*
    507 	     * Flag this as something we need to re-export.
    508 	     * No point actually exporting it now though,
    509 	     * the child can do it at the last minute.
    510 	     */
    511 	    v->flags |= VAR_EXPORTED | VAR_REEXPORT;
    512 	    return TRUE;
    513 	}
    514 	if (v->flags & VAR_IN_USE) {
    515 	    /*
    516 	     * We recursed while exporting in a child.
    517 	     * This isn't going to end well, just skip it.
    518 	     */
    519 	    return FALSE;
    520 	}
    521 
    522 	expr = str_concat3("${", name, "}");
    523 	val = Var_Subst(expr, VAR_GLOBAL, VARE_WANTRES);
    524 	setenv(name, val, 1);
    525 	free(val);
    526 	free(expr);
    527     } else {
    528 	if (parent)
    529 	    v->flags &= ~(unsigned)VAR_REEXPORT;	/* once will do */
    530 	if (parent || !(v->flags & VAR_EXPORTED))
    531 	    setenv(name, val, 1);
    532     }
    533     /*
    534      * This is so Var_Set knows to call Var_Export again...
    535      */
    536     if (parent) {
    537 	v->flags |= VAR_EXPORTED;
    538     }
    539     return TRUE;
    540 }
    541 
    542 static void
    543 Var_ExportVars_callback(void *entry, void *unused MAKE_ATTR_UNUSED)
    544 {
    545     Var *var = entry;
    546     Var_Export1(var->name, 0);
    547 }
    548 
    549 /*
    550  * This gets called from our children.
    551  */
    552 void
    553 Var_ExportVars(void)
    554 {
    555     char *val;
    556 
    557     /*
    558      * Several make's support this sort of mechanism for tracking
    559      * recursion - but each uses a different name.
    560      * We allow the makefiles to update MAKELEVEL and ensure
    561      * children see a correctly incremented value.
    562      */
    563     char tmp[BUFSIZ];
    564     snprintf(tmp, sizeof(tmp), "%d", makelevel + 1);
    565     setenv(MAKE_LEVEL_ENV, tmp, 1);
    566 
    567     if (var_exportedVars == VAR_EXPORTED_NONE)
    568 	return;
    569 
    570     if (var_exportedVars == VAR_EXPORTED_ALL) {
    571 	/* Ouch! This is crazy... */
    572 	Hash_ForEach(&VAR_GLOBAL->context, Var_ExportVars_callback, NULL);
    573 	return;
    574     }
    575 
    576     val = Var_Subst("${" MAKE_EXPORTED ":O:u}", VAR_GLOBAL, VARE_WANTRES);
    577     if (*val) {
    578 	Words words = Str_Words(val, FALSE);
    579 	size_t i;
    580 
    581 	for (i = 0; i < words.len; i++)
    582 	    Var_Export1(words.words[i], 0);
    583 	Words_Free(words);
    584     }
    585     free(val);
    586 }
    587 
    588 /*
    589  * This is called when .export is seen or .MAKE.EXPORTED is modified.
    590  *
    591  * It is also called when any exported variable is modified.
    592  * XXX: Is it really?
    593  *
    594  * str has the format "[-env|-literal] varname...".
    595  */
    596 void
    597 Var_Export(const char *str, Boolean isExport)
    598 {
    599     VarExportFlags flags;
    600     char *val;
    601 
    602     if (isExport && str[0] == '\0') {
    603 	var_exportedVars = VAR_EXPORTED_ALL; /* use with caution! */
    604 	return;
    605     }
    606 
    607     flags = 0;
    608     if (strncmp(str, "-env", 4) == 0) {
    609 	str += 4;
    610     } else if (strncmp(str, "-literal", 8) == 0) {
    611 	str += 8;
    612 	flags |= VAR_EXPORT_LITERAL;
    613     } else {
    614 	flags |= VAR_EXPORT_PARENT;
    615     }
    616 
    617     val = Var_Subst(str, VAR_GLOBAL, VARE_WANTRES);
    618     if (val[0] != '\0') {
    619 	Words words = Str_Words(val, FALSE);
    620 
    621 	size_t i;
    622 	for (i = 0; i < words.len; i++) {
    623 	    const char *name = words.words[i];
    624 	    if (Var_Export1(name, flags)) {
    625 		if (var_exportedVars != VAR_EXPORTED_ALL)
    626 		    var_exportedVars = VAR_EXPORTED_YES;
    627 		if (isExport && (flags & VAR_EXPORT_PARENT)) {
    628 		    Var_Append(MAKE_EXPORTED, name, VAR_GLOBAL);
    629 		}
    630 	    }
    631 	}
    632 	Words_Free(words);
    633     }
    634     free(val);
    635 }
    636 
    637 
    638 extern char **environ;
    639 
    640 /*
    641  * This is called when .unexport[-env] is seen.
    642  *
    643  * str must have the form "unexport[-env] varname...".
    644  */
    645 void
    646 Var_UnExport(const char *str)
    647 {
    648     const char *varnames;
    649     char *varnames_freeIt;
    650     Boolean unexport_env;
    651 
    652     varnames = NULL;
    653     varnames_freeIt = NULL;
    654 
    655     str += strlen("unexport");
    656     unexport_env = strncmp(str, "-env", 4) == 0;
    657     if (unexport_env) {
    658 	const char *cp;
    659 	char **newenv;
    660 
    661 	cp = getenv(MAKE_LEVEL_ENV);	/* we should preserve this */
    662 	if (environ == savedEnv) {
    663 	    /* we have been here before! */
    664 	    newenv = bmake_realloc(environ, 2 * sizeof(char *));
    665 	} else {
    666 	    if (savedEnv) {
    667 		free(savedEnv);
    668 		savedEnv = NULL;
    669 	    }
    670 	    newenv = bmake_malloc(2 * sizeof(char *));
    671 	}
    672 
    673 	/* Note: we cannot safely free() the original environ. */
    674 	environ = savedEnv = newenv;
    675 	newenv[0] = NULL;
    676 	newenv[1] = NULL;
    677 	if (cp && *cp)
    678 	    setenv(MAKE_LEVEL_ENV, cp, 1);
    679     } else {
    680 	for (; ch_isspace(*str); str++)
    681 	    continue;
    682 	if (str[0] != '\0')
    683 	    varnames = str;
    684     }
    685 
    686     if (varnames == NULL) {
    687 	/* Using .MAKE.EXPORTED */
    688 	varnames = varnames_freeIt = Var_Subst("${" MAKE_EXPORTED ":O:u}",
    689 					       VAR_GLOBAL, VARE_WANTRES);
    690     }
    691 
    692     {
    693 	Var *v;
    694 	size_t i;
    695 
    696 	Words words = Str_Words(varnames, FALSE);
    697 	for (i = 0; i < words.len; i++) {
    698 	    const char *varname = words.words[i];
    699 	    v = VarFind(varname, VAR_GLOBAL, 0);
    700 	    if (v == NULL) {
    701 		VAR_DEBUG("Not unexporting \"%s\" (not found)\n", varname);
    702 		continue;
    703 	    }
    704 
    705 	    VAR_DEBUG("Unexporting \"%s\"\n", varname);
    706 	    if (!unexport_env && (v->flags & VAR_EXPORTED) &&
    707 		!(v->flags & VAR_REEXPORT))
    708 		unsetenv(v->name);
    709 	    v->flags &= ~(unsigned)(VAR_EXPORTED | VAR_REEXPORT);
    710 
    711 	    /*
    712 	     * If we are unexporting a list,
    713 	     * remove each one from .MAKE.EXPORTED.
    714 	     * If we are removing them all,
    715 	     * just delete .MAKE.EXPORTED below.
    716 	     */
    717 	    if (varnames == str) {
    718 		char *expr = str_concat3("${" MAKE_EXPORTED ":N", v->name, "}");
    719 		char *cp = Var_Subst(expr, VAR_GLOBAL, VARE_WANTRES);
    720 		Var_Set(MAKE_EXPORTED, cp, VAR_GLOBAL);
    721 		free(cp);
    722 		free(expr);
    723 	    }
    724 	}
    725 	Words_Free(words);
    726 	if (varnames != str) {
    727 	    Var_Delete(MAKE_EXPORTED, VAR_GLOBAL);
    728 	    free(varnames_freeIt);
    729 	}
    730     }
    731 }
    732 
    733 /* See Var_Set for documentation. */
    734 void
    735 Var_Set_with_flags(const char *name, const char *val, GNode *ctxt,
    736 		   VarSet_Flags flags)
    737 {
    738     const char *unexpanded_name = name;
    739     char *name_freeIt = NULL;
    740     Var *v;
    741 
    742     assert(val != NULL);
    743 
    744     /*
    745      * We only look for a variable in the given context since anything set
    746      * here will override anything in a lower context, so there's not much
    747      * point in searching them all just to save a bit of memory...
    748      */
    749     if (strchr(name, '$') != NULL)
    750 	name = name_freeIt = Var_Subst(name, ctxt, VARE_WANTRES);
    751 
    752     if (name[0] == '\0') {
    753 	VAR_DEBUG("Var_Set(\"%s\", \"%s\", ...) "
    754 		  "name expands to empty string - ignored\n",
    755 		  unexpanded_name, val);
    756 	free(name_freeIt);
    757 	return;
    758     }
    759 
    760     if (ctxt == VAR_GLOBAL) {
    761 	v = VarFind(name, VAR_CMD, 0);
    762 	if (v != NULL) {
    763 	    if (v->flags & VAR_FROM_CMD) {
    764 		VAR_DEBUG("%s:%s = %s ignored!\n", ctxt->name, name, val);
    765 		goto out;
    766 	    }
    767 	    VarFreeEnv(v, TRUE);
    768 	}
    769     }
    770 
    771     v = VarFind(name, ctxt, 0);
    772     if (v == NULL) {
    773 	if (ctxt == VAR_CMD && !(flags & VAR_NO_EXPORT)) {
    774 	    /*
    775 	     * This var would normally prevent the same name being added
    776 	     * to VAR_GLOBAL, so delete it from there if needed.
    777 	     * Otherwise -V name may show the wrong value.
    778 	     */
    779 	    Var_Delete(name, VAR_GLOBAL);
    780 	}
    781 	VarAdd(name, val, ctxt, flags);
    782     } else {
    783 	if ((v->flags & VAR_READONLY) && !(flags & VAR_SET_READONLY)) {
    784 	    VAR_DEBUG("%s:%s = %s ignored (read-only)\n",
    785 	      ctxt->name, name, val);
    786 	    goto out;
    787 	}
    788 	Buf_Empty(&v->val);
    789 	if (val)
    790 	    Buf_AddStr(&v->val, val);
    791 
    792 	VAR_DEBUG("%s:%s = %s\n", ctxt->name, name, val);
    793 	if (v->flags & VAR_EXPORTED) {
    794 	    Var_Export1(name, VAR_EXPORT_PARENT);
    795 	}
    796     }
    797     /*
    798      * Any variables given on the command line are automatically exported
    799      * to the environment (as per POSIX standard)
    800      * Other than internals.
    801      */
    802     if (ctxt == VAR_CMD && !(flags & VAR_NO_EXPORT) && name[0] != '.') {
    803 	if (v == NULL) {
    804 	    /* we just added it */
    805 	    v = VarFind(name, ctxt, 0);
    806 	}
    807 	if (v != NULL)
    808 	    v->flags |= VAR_FROM_CMD;
    809 	/*
    810 	 * If requested, don't export these in the environment
    811 	 * individually.  We still put them in MAKEOVERRIDES so
    812 	 * that the command-line settings continue to override
    813 	 * Makefile settings.
    814 	 */
    815 	if (!varNoExportEnv)
    816 	    setenv(name, val ? val : "", 1);
    817 
    818 	Var_Append(MAKEOVERRIDES, name, VAR_GLOBAL);
    819     }
    820     if (name[0] == '.' && strcmp(name, SAVE_DOLLARS) == 0)
    821 	save_dollars = s2Boolean(val, save_dollars);
    822 
    823 out:
    824     free(name_freeIt);
    825     if (v != NULL)
    826 	VarFreeEnv(v, TRUE);
    827 }
    828 
    829 /*-
    830  *-----------------------------------------------------------------------
    831  * Var_Set --
    832  *	Set the variable name to the value val in the given context.
    833  *
    834  *	If the variable doesn't yet exist, it is created.
    835  *	Otherwise the new value overwrites and replaces the old value.
    836  *
    837  * Input:
    838  *	name		name of variable to set
    839  *	val		value to give to the variable
    840  *	ctxt		context in which to set it
    841  *
    842  * Notes:
    843  *	The variable is searched for only in its context before being
    844  *	created in that context. I.e. if the context is VAR_GLOBAL,
    845  *	only VAR_GLOBAL->context is searched. Likewise if it is VAR_CMD, only
    846  *	VAR_CMD->context is searched. This is done to avoid the literally
    847  *	thousands of unnecessary strcmp's that used to be done to
    848  *	set, say, $(@) or $(<).
    849  *	If the context is VAR_GLOBAL though, we check if the variable
    850  *	was set in VAR_CMD from the command line and skip it if so.
    851  *-----------------------------------------------------------------------
    852  */
    853 void
    854 Var_Set(const char *name, const char *val, GNode *ctxt)
    855 {
    856     Var_Set_with_flags(name, val, ctxt, 0);
    857 }
    858 
    859 /*-
    860  *-----------------------------------------------------------------------
    861  * Var_Append --
    862  *	The variable of the given name has the given value appended to it in
    863  *	the given context.
    864  *
    865  *	If the variable doesn't exist, it is created. Otherwise the strings
    866  *	are concatenated, with a space in between.
    867  *
    868  * Input:
    869  *	name		name of variable to modify
    870  *	val		string to append to it
    871  *	ctxt		context in which this should occur
    872  *
    873  * Notes:
    874  *	Only if the variable is being sought in the global context is the
    875  *	environment searched.
    876  *	XXX: Knows its calling circumstances in that if called with ctxt
    877  *	an actual target, it will only search that context since only
    878  *	a local variable could be being appended to. This is actually
    879  *	a big win and must be tolerated.
    880  *-----------------------------------------------------------------------
    881  */
    882 void
    883 Var_Append(const char *name, const char *val, GNode *ctxt)
    884 {
    885     char *name_freeIt = NULL;
    886     Var *v;
    887 
    888     assert(val != NULL);
    889 
    890     if (strchr(name, '$') != NULL) {
    891 	const char *unexpanded_name = name;
    892 	name = name_freeIt = Var_Subst(name, ctxt, VARE_WANTRES);
    893 	if (name[0] == '\0') {
    894 	    VAR_DEBUG("Var_Append(\"%s\", \"%s\", ...) "
    895 		      "name expands to empty string - ignored\n",
    896 		      unexpanded_name, val);
    897 	    free(name_freeIt);
    898 	    return;
    899 	}
    900     }
    901 
    902     v = VarFind(name, ctxt, ctxt == VAR_GLOBAL ? (FIND_CMD | FIND_ENV) : 0);
    903 
    904     if (v == NULL) {
    905 	Var_Set(name, val, ctxt);
    906     } else if (ctxt == VAR_CMD || !(v->flags & VAR_FROM_CMD)) {
    907 	Buf_AddByte(&v->val, ' ');
    908 	Buf_AddStr(&v->val, val);
    909 
    910 	VAR_DEBUG("%s:%s = %s\n", ctxt->name, name,
    911 		  Buf_GetAll(&v->val, NULL));
    912 
    913 	if (v->flags & VAR_FROM_ENV) {
    914 	    Hash_Entry *h;
    915 
    916 	    /*
    917 	     * If the original variable came from the environment, we
    918 	     * have to install it in the global context (we could place
    919 	     * it in the environment, but then we should provide a way to
    920 	     * export other variables...)
    921 	     */
    922 	    v->flags &= ~(unsigned)VAR_FROM_ENV;
    923 	    h = Hash_CreateEntry(&ctxt->context, name, NULL);
    924 	    Hash_SetValue(h, v);
    925 	}
    926     }
    927     free(name_freeIt);
    928 }
    929 
    930 /* See if the given variable exists, in the given context or in other
    931  * fallback contexts.
    932  *
    933  * Input:
    934  *	name		Variable to find
    935  *	ctxt		Context in which to start search
    936  */
    937 Boolean
    938 Var_Exists(const char *name, GNode *ctxt)
    939 {
    940     char *name_freeIt = NULL;
    941     Var *v;
    942 
    943     if (strchr(name, '$') != NULL)
    944 	name = name_freeIt = Var_Subst(name, ctxt, VARE_WANTRES);
    945 
    946     v = VarFind(name, ctxt, FIND_CMD | FIND_GLOBAL | FIND_ENV);
    947     free(name_freeIt);
    948     if (v == NULL)
    949 	return FALSE;
    950 
    951     (void)VarFreeEnv(v, TRUE);
    952     return TRUE;
    953 }
    954 
    955 /*-
    956  *-----------------------------------------------------------------------
    957  * Var_Value --
    958  *	Return the unexpanded value of the given variable in the given
    959  *	context, or the usual contexts.
    960  *
    961  * Input:
    962  *	name		name to find
    963  *	ctxt		context in which to search for it
    964  *
    965  * Results:
    966  *	The value if the variable exists, NULL if it doesn't.
    967  *	If the returned value is not NULL, the caller must free *freeIt
    968  *	as soon as the returned value is no longer needed.
    969  *-----------------------------------------------------------------------
    970  */
    971 const char *
    972 Var_Value(const char *name, GNode *ctxt, char **freeIt)
    973 {
    974     Var *v = VarFind(name, ctxt, FIND_ENV | FIND_GLOBAL | FIND_CMD);
    975     char *p;
    976 
    977     *freeIt = NULL;
    978     if (v == NULL)
    979 	return NULL;
    980 
    981     p = Buf_GetAll(&v->val, NULL);
    982     if (VarFreeEnv(v, FALSE))
    983 	*freeIt = p;
    984     return p;
    985 }
    986 
    987 
    988 /* SepBuf is a string being built from "words", interleaved with separators. */
    989 typedef struct {
    990     Buffer buf;
    991     Boolean needSep;
    992     char sep;			/* usually ' ', but see the :ts modifier */
    993 } SepBuf;
    994 
    995 static void
    996 SepBuf_Init(SepBuf *buf, char sep)
    997 {
    998     Buf_Init(&buf->buf, 32 /* bytes */);
    999     buf->needSep = FALSE;
   1000     buf->sep = sep;
   1001 }
   1002 
   1003 static void
   1004 SepBuf_Sep(SepBuf *buf)
   1005 {
   1006     buf->needSep = TRUE;
   1007 }
   1008 
   1009 static void
   1010 SepBuf_AddBytes(SepBuf *buf, const char *mem, size_t mem_size)
   1011 {
   1012     if (mem_size == 0)
   1013 	return;
   1014     if (buf->needSep && buf->sep != '\0') {
   1015 	Buf_AddByte(&buf->buf, buf->sep);
   1016 	buf->needSep = FALSE;
   1017     }
   1018     Buf_AddBytes(&buf->buf, mem, mem_size);
   1019 }
   1020 
   1021 static void
   1022 SepBuf_AddBytesBetween(SepBuf *buf, const char *start, const char *end)
   1023 {
   1024     SepBuf_AddBytes(buf, start, (size_t)(end - start));
   1025 }
   1026 
   1027 static void
   1028 SepBuf_AddStr(SepBuf *buf, const char *str)
   1029 {
   1030     SepBuf_AddBytes(buf, str, strlen(str));
   1031 }
   1032 
   1033 static char *
   1034 SepBuf_Destroy(SepBuf *buf, Boolean free_buf)
   1035 {
   1036     return Buf_Destroy(&buf->buf, free_buf);
   1037 }
   1038 
   1039 
   1040 /* This callback for ModifyWords gets a single word from an expression and
   1041  * typically adds a modification of this word to the buffer. It may also do
   1042  * nothing or add several words. */
   1043 typedef void (*ModifyWordsCallback)(const char *word, SepBuf *buf, void *data);
   1044 
   1045 
   1046 /* Callback for ModifyWords to implement the :H modifier.
   1047  * Add the dirname of the given word to the buffer. */
   1048 static void
   1049 ModifyWord_Head(const char *word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
   1050 {
   1051     const char *slash = strrchr(word, '/');
   1052     if (slash != NULL)
   1053 	SepBuf_AddBytesBetween(buf, word, slash);
   1054     else
   1055 	SepBuf_AddStr(buf, ".");
   1056 }
   1057 
   1058 /* Callback for ModifyWords to implement the :T modifier.
   1059  * Add the basename of the given word to the buffer. */
   1060 static void
   1061 ModifyWord_Tail(const char *word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
   1062 {
   1063     const char *slash = strrchr(word, '/');
   1064     const char *base = slash != NULL ? slash + 1 : word;
   1065     SepBuf_AddStr(buf, base);
   1066 }
   1067 
   1068 /* Callback for ModifyWords to implement the :E modifier.
   1069  * Add the filename suffix of the given word to the buffer, if it exists. */
   1070 static void
   1071 ModifyWord_Suffix(const char *word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
   1072 {
   1073     const char *dot = strrchr(word, '.');
   1074     if (dot != NULL)
   1075 	SepBuf_AddStr(buf, dot + 1);
   1076 }
   1077 
   1078 /* Callback for ModifyWords to implement the :R modifier.
   1079  * Add the basename of the given word to the buffer. */
   1080 static void
   1081 ModifyWord_Root(const char *word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
   1082 {
   1083     const char *dot = strrchr(word, '.');
   1084     size_t len = dot != NULL ? (size_t)(dot - word) : strlen(word);
   1085     SepBuf_AddBytes(buf, word, len);
   1086 }
   1087 
   1088 /* Callback for ModifyWords to implement the :M modifier.
   1089  * Place the word in the buffer if it matches the given pattern. */
   1090 static void
   1091 ModifyWord_Match(const char *word, SepBuf *buf, void *data)
   1092 {
   1093     const char *pattern = data;
   1094     VAR_DEBUG("VarMatch [%s] [%s]\n", word, pattern);
   1095     if (Str_Match(word, pattern))
   1096 	SepBuf_AddStr(buf, word);
   1097 }
   1098 
   1099 /* Callback for ModifyWords to implement the :N modifier.
   1100  * Place the word in the buffer if it doesn't match the given pattern. */
   1101 static void
   1102 ModifyWord_NoMatch(const char *word, SepBuf *buf, void *data)
   1103 {
   1104     const char *pattern = data;
   1105     if (!Str_Match(word, pattern))
   1106 	SepBuf_AddStr(buf, word);
   1107 }
   1108 
   1109 #ifdef SYSVVARSUB
   1110 /*-
   1111  *-----------------------------------------------------------------------
   1112  * Str_SYSVMatch --
   1113  *	Check word against pattern for a match (% is wild),
   1114  *
   1115  * Input:
   1116  *	word		Word to examine
   1117  *	pattern		Pattern to examine against
   1118  *
   1119  * Results:
   1120  *	Returns the start of the match, or NULL.
   1121  *	*match_len returns the length of the match, if any.
   1122  *	*hasPercent returns whether the pattern contains a percent.
   1123  *-----------------------------------------------------------------------
   1124  */
   1125 static const char *
   1126 Str_SYSVMatch(const char *word, const char *pattern, size_t *match_len,
   1127 	      Boolean *hasPercent)
   1128 {
   1129     const char *p = pattern;
   1130     const char *w = word;
   1131     const char *percent;
   1132     size_t w_len;
   1133     size_t p_len;
   1134     const char *w_tail;
   1135 
   1136     *hasPercent = FALSE;
   1137     if (*p == '\0') {		/* ${VAR:=suffix} */
   1138 	*match_len = strlen(w);	/* Null pattern is the whole string */
   1139 	return w;
   1140     }
   1141 
   1142     percent = strchr(p, '%');
   1143     if (percent != NULL) {	/* ${VAR:...%...=...} */
   1144 	*hasPercent = TRUE;
   1145 	if (*w == '\0')
   1146 	    return NULL;	/* empty word does not match pattern */
   1147 
   1148 	/* check that the prefix matches */
   1149 	for (; p != percent && *w != '\0' && *w == *p; w++, p++)
   1150 	    continue;
   1151 	if (p != percent)
   1152 	    return NULL;	/* No match */
   1153 
   1154 	p++;			/* Skip the percent */
   1155 	if (*p == '\0') {
   1156 	    /* No more pattern, return the rest of the string */
   1157 	    *match_len = strlen(w);
   1158 	    return w;
   1159 	}
   1160     }
   1161 
   1162     /* Test whether the tail matches */
   1163     w_len = strlen(w);
   1164     p_len = strlen(p);
   1165     if (w_len < p_len)
   1166 	return NULL;
   1167 
   1168     w_tail = w + w_len - p_len;
   1169     if (memcmp(p, w_tail, p_len) != 0)
   1170 	return NULL;
   1171 
   1172     *match_len = (size_t)(w_tail - w);
   1173     return w;
   1174 }
   1175 
   1176 typedef struct {
   1177     GNode *ctx;
   1178     const char *lhs;
   1179     const char *rhs;
   1180 } ModifyWord_SYSVSubstArgs;
   1181 
   1182 /* Callback for ModifyWords to implement the :%.from=%.to modifier. */
   1183 static void
   1184 ModifyWord_SYSVSubst(const char *word, SepBuf *buf, void *data)
   1185 {
   1186     const ModifyWord_SYSVSubstArgs *args = data;
   1187     char *rhs_expanded;
   1188     const char *rhs;
   1189     const char *percent;
   1190 
   1191     size_t match_len;
   1192     Boolean lhsPercent;
   1193     const char *match = Str_SYSVMatch(word, args->lhs, &match_len, &lhsPercent);
   1194     if (match == NULL) {
   1195 	SepBuf_AddStr(buf, word);
   1196 	return;
   1197     }
   1198 
   1199     /* Append rhs to the buffer, substituting the first '%' with the
   1200      * match, but only if the lhs had a '%' as well. */
   1201 
   1202     rhs_expanded = Var_Subst(args->rhs, args->ctx, VARE_WANTRES);
   1203 
   1204     rhs = rhs_expanded;
   1205     percent = strchr(rhs, '%');
   1206 
   1207     if (percent != NULL && lhsPercent) {
   1208 	/* Copy the prefix of the replacement pattern */
   1209 	SepBuf_AddBytesBetween(buf, rhs, percent);
   1210 	rhs = percent + 1;
   1211     }
   1212     if (percent != NULL || !lhsPercent)
   1213 	SepBuf_AddBytes(buf, match, match_len);
   1214 
   1215     /* Append the suffix of the replacement pattern */
   1216     SepBuf_AddStr(buf, rhs);
   1217 
   1218     free(rhs_expanded);
   1219 }
   1220 #endif
   1221 
   1222 
   1223 typedef struct {
   1224     const char	*lhs;
   1225     size_t	lhsLen;
   1226     const char	*rhs;
   1227     size_t	rhsLen;
   1228     VarPatternFlags pflags;
   1229     Boolean	matched;
   1230 } ModifyWord_SubstArgs;
   1231 
   1232 /* Callback for ModifyWords to implement the :S,from,to, modifier.
   1233  * Perform a string substitution on the given word. */
   1234 static void
   1235 ModifyWord_Subst(const char *word, SepBuf *buf, void *data)
   1236 {
   1237     size_t wordLen = strlen(word);
   1238     ModifyWord_SubstArgs *args = data;
   1239     const char *match;
   1240 
   1241     if ((args->pflags & VARP_SUB_ONE) && args->matched)
   1242 	goto nosub;
   1243 
   1244     if (args->pflags & VARP_ANCHOR_START) {
   1245 	if (wordLen < args->lhsLen ||
   1246 	    memcmp(word, args->lhs, args->lhsLen) != 0)
   1247 	    goto nosub;
   1248 
   1249 	if (args->pflags & VARP_ANCHOR_END) {
   1250 	    if (wordLen != args->lhsLen)
   1251 		goto nosub;
   1252 
   1253 	    /* :S,^whole$,replacement, */
   1254 	    SepBuf_AddBytes(buf, args->rhs, args->rhsLen);
   1255 	    args->matched = TRUE;
   1256 	} else {
   1257 	    /* :S,^prefix,replacement, */
   1258 	    SepBuf_AddBytes(buf, args->rhs, args->rhsLen);
   1259 	    SepBuf_AddBytes(buf, word + args->lhsLen, wordLen - args->lhsLen);
   1260 	    args->matched = TRUE;
   1261 	}
   1262 	return;
   1263     }
   1264 
   1265     if (args->pflags & VARP_ANCHOR_END) {
   1266 	const char *start;
   1267 
   1268 	if (wordLen < args->lhsLen)
   1269 	    goto nosub;
   1270 
   1271 	start = word + (wordLen - args->lhsLen);
   1272 	if (memcmp(start, args->lhs, args->lhsLen) != 0)
   1273 	    goto nosub;
   1274 
   1275 	/* :S,suffix$,replacement, */
   1276 	SepBuf_AddBytesBetween(buf, word, start);
   1277 	SepBuf_AddBytes(buf, args->rhs, args->rhsLen);
   1278 	args->matched = TRUE;
   1279 	return;
   1280     }
   1281 
   1282     /* unanchored case, may match more than once */
   1283     while ((match = Str_FindSubstring(word, args->lhs)) != NULL) {
   1284 	SepBuf_AddBytesBetween(buf, word, match);
   1285 	SepBuf_AddBytes(buf, args->rhs, args->rhsLen);
   1286 	args->matched = TRUE;
   1287 	wordLen -= (size_t)(match - word) + args->lhsLen;
   1288 	word += (size_t)(match - word) + args->lhsLen;
   1289 	if (wordLen == 0 || !(args->pflags & VARP_SUB_GLOBAL))
   1290 	    break;
   1291     }
   1292 nosub:
   1293     SepBuf_AddBytes(buf, word, wordLen);
   1294 }
   1295 
   1296 #ifndef NO_REGEX
   1297 /* Print the error caused by a regcomp or regexec call. */
   1298 static void
   1299 VarREError(int reerr, regex_t *pat, const char *str)
   1300 {
   1301     size_t errlen = regerror(reerr, pat, 0, 0);
   1302     char *errbuf = bmake_malloc(errlen);
   1303     regerror(reerr, pat, errbuf, errlen);
   1304     Error("%s: %s", str, errbuf);
   1305     free(errbuf);
   1306 }
   1307 
   1308 typedef struct {
   1309     regex_t	   re;
   1310     size_t	   nsub;
   1311     char 	  *replace;
   1312     VarPatternFlags pflags;
   1313     Boolean	   matched;
   1314 } ModifyWord_SubstRegexArgs;
   1315 
   1316 /* Callback for ModifyWords to implement the :C/from/to/ modifier.
   1317  * Perform a regex substitution on the given word. */
   1318 static void
   1319 ModifyWord_SubstRegex(const char *word, SepBuf *buf, void *data)
   1320 {
   1321     ModifyWord_SubstRegexArgs *args = data;
   1322     int xrv;
   1323     const char *wp = word;
   1324     char *rp;
   1325     int flags = 0;
   1326     regmatch_t m[10];
   1327 
   1328     if ((args->pflags & VARP_SUB_ONE) && args->matched)
   1329 	goto nosub;
   1330 
   1331 tryagain:
   1332     xrv = regexec(&args->re, wp, args->nsub, m, flags);
   1333 
   1334     switch (xrv) {
   1335     case 0:
   1336 	args->matched = TRUE;
   1337 	SepBuf_AddBytes(buf, wp, (size_t)m[0].rm_so);
   1338 
   1339 	for (rp = args->replace; *rp; rp++) {
   1340 	    if (*rp == '\\' && (rp[1] == '&' || rp[1] == '\\')) {
   1341 		SepBuf_AddBytes(buf, rp + 1, 1);
   1342 		rp++;
   1343 		continue;
   1344 	    }
   1345 
   1346 	    if (*rp == '&') {
   1347 		SepBuf_AddBytesBetween(buf, wp + m[0].rm_so, wp + m[0].rm_eo);
   1348 		continue;
   1349 	    }
   1350 
   1351 	    if (*rp != '\\' || !ch_isdigit(rp[1])) {
   1352 		SepBuf_AddBytes(buf, rp, 1);
   1353 		continue;
   1354 	    }
   1355 
   1356 	    {			/* \0 to \9 backreference */
   1357 		size_t n = (size_t)(rp[1] - '0');
   1358 		rp++;
   1359 
   1360 		if (n >= args->nsub) {
   1361 		    Error("No subexpression \\%zu", n);
   1362 		} else if (m[n].rm_so == -1 && m[n].rm_eo == -1) {
   1363 		    Error("No match for subexpression \\%zu", n);
   1364 		} else {
   1365 		    SepBuf_AddBytesBetween(buf, wp + m[n].rm_so,
   1366 					   wp + m[n].rm_eo);
   1367 		}
   1368 	    }
   1369 	}
   1370 
   1371 	wp += m[0].rm_eo;
   1372 	if (args->pflags & VARP_SUB_GLOBAL) {
   1373 	    flags |= REG_NOTBOL;
   1374 	    if (m[0].rm_so == 0 && m[0].rm_eo == 0) {
   1375 		SepBuf_AddBytes(buf, wp, 1);
   1376 		wp++;
   1377 	    }
   1378 	    if (*wp)
   1379 		goto tryagain;
   1380 	}
   1381 	if (*wp) {
   1382 	    SepBuf_AddStr(buf, wp);
   1383 	}
   1384 	break;
   1385     default:
   1386 	VarREError(xrv, &args->re, "Unexpected regex error");
   1387 	/* fall through */
   1388     case REG_NOMATCH:
   1389     nosub:
   1390 	SepBuf_AddStr(buf, wp);
   1391 	break;
   1392     }
   1393 }
   1394 #endif
   1395 
   1396 
   1397 typedef struct {
   1398     GNode	*ctx;
   1399     char	*tvar;		/* name of temporary variable */
   1400     char	*str;		/* string to expand */
   1401     VarEvalFlags eflags;
   1402 } ModifyWord_LoopArgs;
   1403 
   1404 /* Callback for ModifyWords to implement the :@var (at) ...@ modifier of ODE make. */
   1405 static void
   1406 ModifyWord_Loop(const char *word, SepBuf *buf, void *data)
   1407 {
   1408     const ModifyWord_LoopArgs *args;
   1409     char *s;
   1410 
   1411     if (word[0] == '\0')
   1412 	return;
   1413 
   1414     args = data;
   1415     Var_Set_with_flags(args->tvar, word, args->ctx, VAR_NO_EXPORT);
   1416     s = Var_Subst(args->str, args->ctx, args->eflags);
   1417 
   1418     VAR_DEBUG("ModifyWord_Loop: in \"%s\", replace \"%s\" with \"%s\" "
   1419 	      "to \"%s\"\n",
   1420 	      word, args->tvar, args->str, s);
   1421 
   1422     if (s[0] == '\n' || (buf->buf.count > 0 &&
   1423 			 buf->buf.buffer[buf->buf.count - 1] == '\n'))
   1424 	buf->needSep = FALSE;
   1425     SepBuf_AddStr(buf, s);
   1426     free(s);
   1427 }
   1428 
   1429 
   1430 /*-
   1431  * Implements the :[first..last] modifier.
   1432  * This is a special case of ModifyWords since we want to be able
   1433  * to scan the list backwards if first > last.
   1434  */
   1435 static char *
   1436 VarSelectWords(char sep, Boolean oneBigWord, const char *str, int first,
   1437 	       int last)
   1438 {
   1439     Words words;
   1440     int start, end, step;
   1441     int i;
   1442 
   1443     SepBuf buf;
   1444     SepBuf_Init(&buf, sep);
   1445 
   1446     if (oneBigWord) {
   1447 	/* fake what Str_Words() would do if there were only one word */
   1448 	words.len = 1;
   1449 	words.words = bmake_malloc((words.len + 1) * sizeof(char *));
   1450 	words.freeIt = bmake_strdup(str);
   1451 	words.words[0] = words.freeIt;
   1452 	words.words[1] = NULL;
   1453     } else {
   1454 	words = Str_Words(str, FALSE);
   1455     }
   1456 
   1457     /*
   1458      * Now sanitize the given range.
   1459      * If first or last are negative, convert them to the positive equivalents
   1460      * (-1 gets converted to ac, -2 gets converted to (ac - 1), etc.).
   1461      */
   1462     if (first < 0)
   1463 	first += (int)words.len + 1;
   1464     if (last < 0)
   1465 	last += (int)words.len + 1;
   1466 
   1467     /*
   1468      * We avoid scanning more of the list than we need to.
   1469      */
   1470     if (first > last) {
   1471 	start = MIN((int)words.len, first) - 1;
   1472 	end = MAX(0, last - 1);
   1473 	step = -1;
   1474     } else {
   1475 	start = MAX(0, first - 1);
   1476 	end = MIN((int)words.len, last);
   1477 	step = 1;
   1478     }
   1479 
   1480     for (i = start; (step < 0) == (i >= end); i += step) {
   1481 	SepBuf_AddStr(&buf, words.words[i]);
   1482 	SepBuf_Sep(&buf);
   1483     }
   1484 
   1485     Words_Free(words);
   1486 
   1487     return SepBuf_Destroy(&buf, FALSE);
   1488 }
   1489 
   1490 
   1491 /* Callback for ModifyWords to implement the :tA modifier.
   1492  * Replace each word with the result of realpath() if successful. */
   1493 static void
   1494 ModifyWord_Realpath(const char *word, SepBuf *buf, void *data MAKE_ATTR_UNUSED)
   1495 {
   1496     struct stat st;
   1497     char rbuf[MAXPATHLEN];
   1498 
   1499     const char *rp = cached_realpath(word, rbuf);
   1500     if (rp != NULL && *rp == '/' && stat(rp, &st) == 0)
   1501 	word = rp;
   1502 
   1503     SepBuf_AddStr(buf, word);
   1504 }
   1505 
   1506 /*-
   1507  *-----------------------------------------------------------------------
   1508  * Modify each of the words of the passed string using the given function.
   1509  *
   1510  * Input:
   1511  *	str		String whose words should be modified
   1512  *	modifyWord	Function that modifies a single word
   1513  *	modifyWord_args Custom arguments for modifyWord
   1514  *
   1515  * Results:
   1516  *	A string of all the words modified appropriately.
   1517  *-----------------------------------------------------------------------
   1518  */
   1519 static char *
   1520 ModifyWords(GNode *ctx, char sep, Boolean oneBigWord, const char *str,
   1521 	    ModifyWordsCallback modifyWord, void *modifyWord_args)
   1522 {
   1523     SepBuf result;
   1524     Words words;
   1525     size_t i;
   1526 
   1527     if (oneBigWord) {
   1528 	SepBuf_Init(&result, sep);
   1529 	modifyWord(str, &result, modifyWord_args);
   1530 	return SepBuf_Destroy(&result, FALSE);
   1531     }
   1532 
   1533     SepBuf_Init(&result, sep);
   1534 
   1535     words = Str_Words(str, FALSE);
   1536 
   1537     VAR_DEBUG("ModifyWords: split \"%s\" into %zu words\n", str, words.len);
   1538 
   1539     for (i = 0; i < words.len; i++) {
   1540 	modifyWord(words.words[i], &result, modifyWord_args);
   1541 	if (result.buf.count > 0)
   1542 	    SepBuf_Sep(&result);
   1543     }
   1544 
   1545     Words_Free(words);
   1546 
   1547     return SepBuf_Destroy(&result, FALSE);
   1548 }
   1549 
   1550 
   1551 static char *
   1552 Words_JoinFree(Words words)
   1553 {
   1554     Buffer buf;
   1555     size_t i;
   1556 
   1557     Buf_Init(&buf, 0);
   1558 
   1559     for (i = 0; i < words.len; i++) {
   1560 	if (i != 0)
   1561 	    Buf_AddByte(&buf, ' ');	/* XXX: st->sep, for consistency */
   1562 	Buf_AddStr(&buf, words.words[i]);
   1563     }
   1564 
   1565     Words_Free(words);
   1566 
   1567     return Buf_Destroy(&buf, FALSE);
   1568 }
   1569 
   1570 /* Remove adjacent duplicate words. */
   1571 static char *
   1572 VarUniq(const char *str)
   1573 {
   1574     Words words = Str_Words(str, FALSE);
   1575 
   1576     if (words.len > 1) {
   1577 	size_t i, j;
   1578 	for (j = 0, i = 1; i < words.len; i++)
   1579 	    if (strcmp(words.words[i], words.words[j]) != 0 && (++j != i))
   1580 		words.words[j] = words.words[i];
   1581 	words.len = j + 1;
   1582     }
   1583 
   1584     return Words_JoinFree(words);
   1585 }
   1586 
   1587 
   1588 /* Quote shell meta-characters and space characters in the string.
   1589  * If quoteDollar is set, also quote and double any '$' characters. */
   1590 static char *
   1591 VarQuote(const char *str, Boolean quoteDollar)
   1592 {
   1593     char *res;
   1594     Buffer buf;
   1595     Buf_Init(&buf, 0);
   1596 
   1597     for (; *str != '\0'; str++) {
   1598 	if (*str == '\n') {
   1599 	    const char *newline = Shell_GetNewline();
   1600 	    if (newline == NULL)
   1601 		newline = "\\\n";
   1602 	    Buf_AddStr(&buf, newline);
   1603 	    continue;
   1604 	}
   1605 	if (ch_isspace(*str) || ismeta((unsigned char)*str))
   1606 	    Buf_AddByte(&buf, '\\');
   1607 	Buf_AddByte(&buf, *str);
   1608 	if (quoteDollar && *str == '$')
   1609 	    Buf_AddStr(&buf, "\\$");
   1610     }
   1611 
   1612     res = Buf_Destroy(&buf, FALSE);
   1613     VAR_DEBUG("QuoteMeta: [%s]\n", res);
   1614     return res;
   1615 }
   1616 
   1617 /* Compute the 32-bit hash of the given string, using the MurmurHash3
   1618  * algorithm. Output is encoded as 8 hex digits, in Little Endian order. */
   1619 static char *
   1620 VarHash(const char *str)
   1621 {
   1622     static const char    hexdigits[16] = "0123456789abcdef";
   1623     const unsigned char *ustr = (const unsigned char *)str;
   1624 
   1625     uint32_t h  = 0x971e137bU;
   1626     uint32_t c1 = 0x95543787U;
   1627     uint32_t c2 = 0x2ad7eb25U;
   1628     size_t len2 = strlen(str);
   1629 
   1630     char *buf;
   1631     size_t i;
   1632 
   1633     size_t len;
   1634     for (len = len2; len; ) {
   1635 	uint32_t k = 0;
   1636 	switch (len) {
   1637 	default:
   1638 	    k = ((uint32_t)ustr[3] << 24) |
   1639 		((uint32_t)ustr[2] << 16) |
   1640 		((uint32_t)ustr[1] << 8) |
   1641 		(uint32_t)ustr[0];
   1642 	    len -= 4;
   1643 	    ustr += 4;
   1644 	    break;
   1645 	case 3:
   1646 	    k |= (uint32_t)ustr[2] << 16;
   1647 	    /* FALLTHROUGH */
   1648 	case 2:
   1649 	    k |= (uint32_t)ustr[1] << 8;
   1650 	    /* FALLTHROUGH */
   1651 	case 1:
   1652 	    k |= (uint32_t)ustr[0];
   1653 	    len = 0;
   1654 	}
   1655 	c1 = c1 * 5 + 0x7b7d159cU;
   1656 	c2 = c2 * 5 + 0x6bce6396U;
   1657 	k *= c1;
   1658 	k = (k << 11) ^ (k >> 21);
   1659 	k *= c2;
   1660 	h = (h << 13) ^ (h >> 19);
   1661 	h = h * 5 + 0x52dce729U;
   1662 	h ^= k;
   1663     }
   1664     h ^= (uint32_t)len2;
   1665     h *= 0x85ebca6b;
   1666     h ^= h >> 13;
   1667     h *= 0xc2b2ae35;
   1668     h ^= h >> 16;
   1669 
   1670     buf = bmake_malloc(9);
   1671     for (i = 0; i < 8; i++) {
   1672 	buf[i] = hexdigits[h & 0x0f];
   1673 	h >>= 4;
   1674     }
   1675     buf[8] = '\0';
   1676     return buf;
   1677 }
   1678 
   1679 static char *
   1680 VarStrftime(const char *fmt, Boolean zulu, time_t tim)
   1681 {
   1682     char buf[BUFSIZ];
   1683 
   1684     if (!tim)
   1685 	time(&tim);
   1686     if (!*fmt)
   1687 	fmt = "%c";
   1688     strftime(buf, sizeof(buf), fmt, zulu ? gmtime(&tim) : localtime(&tim));
   1689 
   1690     buf[sizeof(buf) - 1] = '\0';
   1691     return bmake_strdup(buf);
   1692 }
   1693 
   1694 /* The ApplyModifier functions all work in the same way.  They get the
   1695  * current parsing position (pp) and parse the modifier from there.  The
   1696  * modifier typically lasts until the next ':', or a closing '}' or ')'
   1697  * (taken from st->endc), or the end of the string (parse error).
   1698  *
   1699  * The high-level behavior of these functions is:
   1700  *
   1701  * 1. parse the modifier
   1702  * 2. evaluate the modifier
   1703  * 3. housekeeping
   1704  *
   1705  * Parsing the modifier
   1706  *
   1707  * If parsing succeeds, the parsing position *pp is updated to point to the
   1708  * first character following the modifier, which typically is either ':' or
   1709  * st->endc.
   1710  *
   1711  * If parsing fails because of a missing delimiter (as in the :S, :C or :@
   1712  * modifiers), set st->missing_delim and return AMR_CLEANUP.
   1713  *
   1714  * If parsing fails because the modifier is unknown, return AMR_UNKNOWN to
   1715  * try the SysV modifier ${VAR:from=to} as fallback.  This should only be
   1716  * done as long as there have been no side effects from evaluating nested
   1717  * variables, to avoid evaluating them more than once.  In this case, the
   1718  * parsing position must not be updated.  (XXX: Why not? The original parsing
   1719  * position is well-known in ApplyModifiers.)
   1720  *
   1721  * If parsing fails and the SysV modifier ${VAR:from=to} should not be used
   1722  * as a fallback, either issue an error message using Error or Parse_Error
   1723  * and then return AMR_CLEANUP, or return AMR_BAD for the default error
   1724  * message.  Both of these return values will stop processing the variable
   1725  * expression.  (XXX: As of 2020-08-23, evaluation of the whole string
   1726  * continues nevertheless after skipping a few bytes, which essentially is
   1727  * undefined behavior.  Not in the sense of C, but still it's impossible to
   1728  * predict what happens in the parser.)
   1729  *
   1730  * Evaluating the modifier
   1731  *
   1732  * After parsing, the modifier is evaluated.  The side effects from evaluating
   1733  * nested variable expressions in the modifier text often already happen
   1734  * during parsing though.
   1735  *
   1736  * Evaluating the modifier usually takes the current value of the variable
   1737  * expression from st->val, or the variable name from st->v->name and stores
   1738  * the result in st->newVal.
   1739  *
   1740  * If evaluating fails (as of 2020-08-23), an error message is printed using
   1741  * Error.  This function has no side-effects, it really just prints the error
   1742  * message.  Processing the expression continues as if everything were ok.
   1743  * XXX: This should be fixed by adding proper error handling to Var_Subst,
   1744  * Var_Parse, ApplyModifiers and ModifyWords.
   1745  *
   1746  * Housekeeping
   1747  *
   1748  * Some modifiers such as :D and :U turn undefined expressions into defined
   1749  * expressions (see VEF_UNDEF, VEF_DEF).
   1750  *
   1751  * Some modifiers need to free some memory.
   1752  */
   1753 
   1754 typedef enum VarExprFlags {
   1755     /* The variable expression is based on an undefined variable. */
   1756     VEF_UNDEF = 0x01,
   1757     /* The variable expression started as an undefined expression, but one
   1758      * of the modifiers (such as :D or :U) has turned the expression from
   1759      * undefined to defined. */
   1760     VEF_DEF = 0x02
   1761 } VarExprFlags;
   1762 
   1763 ENUM_FLAGS_RTTI_2(VarExprFlags,
   1764 		  VEF_UNDEF, VEF_DEF);
   1765 
   1766 
   1767 typedef struct {
   1768     const char startc;		/* '\0' or '{' or '(' */
   1769     const char endc;		/* '\0' or '}' or ')' */
   1770     Var * const v;
   1771     GNode * const ctxt;
   1772     const VarEvalFlags eflags;
   1773 
   1774     char *val;			/* The old value of the expression,
   1775 				 * before applying the modifier, never NULL */
   1776     char *newVal;		/* The new value of the expression,
   1777 				 * after applying the modifier, never NULL */
   1778     char missing_delim;		/* For error reporting */
   1779 
   1780     char sep;			/* Word separator in expansions
   1781 				 * (see the :ts modifier) */
   1782     Boolean oneBigWord;		/* TRUE if some modifiers that otherwise split
   1783 				 * the variable value into words, like :S and
   1784 				 * :C, treat the variable value as a single big
   1785 				 * word, possibly containing spaces. */
   1786     VarExprFlags exprFlags;
   1787 } ApplyModifiersState;
   1788 
   1789 static void
   1790 ApplyModifiersState_Define(ApplyModifiersState *st)
   1791 {
   1792     if (st->exprFlags & VEF_UNDEF)
   1793         st->exprFlags |= VEF_DEF;
   1794 }
   1795 
   1796 typedef enum {
   1797     AMR_OK,			/* Continue parsing */
   1798     AMR_UNKNOWN,		/* Not a match, try other modifiers as well */
   1799     AMR_BAD,			/* Error out with "Bad modifier" message */
   1800     AMR_CLEANUP			/* Error out, with "Unfinished modifier"
   1801 				 * if st->missing_delim is set. */
   1802 } ApplyModifierResult;
   1803 
   1804 /*-
   1805  * Parse a part of a modifier such as the "from" and "to" in :S/from/to/
   1806  * or the "var" or "replacement" in :@var@replacement+${var}@, up to and
   1807  * including the next unescaped delimiter.  The delimiter, as well as the
   1808  * backslash or the dollar, can be escaped with a backslash.
   1809  *
   1810  * Return the parsed (and possibly expanded) string, or NULL if no delimiter
   1811  * was found.  On successful return, the parsing position pp points right
   1812  * after the delimiter.  The delimiter is not included in the returned
   1813  * value though.
   1814  */
   1815 static char *
   1816 ParseModifierPart(
   1817     const char **pp,		/* The parsing position, updated upon return */
   1818     int delim,			/* Parsing stops at this delimiter */
   1819     VarEvalFlags eflags,	/* Flags for evaluating nested variables;
   1820 				 * if VARE_WANTRES is not set, the text is
   1821 				 * only parsed */
   1822     ApplyModifiersState *st,
   1823     size_t *out_length,		/* Optionally stores the length of the returned
   1824 				 * string, just to save another strlen call. */
   1825     VarPatternFlags *out_pflags,/* For the first part of the :S modifier,
   1826 				 * sets the VARP_ANCHOR_END flag if the last
   1827 				 * character of the pattern is a $. */
   1828     ModifyWord_SubstArgs *subst	/* For the second part of the :S modifier,
   1829 				 * allow ampersands to be escaped and replace
   1830 				 * unescaped ampersands with subst->lhs. */
   1831 ) {
   1832     Buffer buf;
   1833     const char *p;
   1834     char *rstr;
   1835 
   1836     Buf_Init(&buf, 0);
   1837 
   1838     /*
   1839      * Skim through until the matching delimiter is found;
   1840      * pick up variable substitutions on the way. Also allow
   1841      * backslashes to quote the delimiter, $, and \, but don't
   1842      * touch other backslashes.
   1843      */
   1844     p = *pp;
   1845     while (*p != '\0' && *p != delim) {
   1846 	const char *varstart;
   1847 
   1848 	Boolean is_escaped = p[0] == '\\' && (
   1849 	    p[1] == delim || p[1] == '\\' || p[1] == '$' ||
   1850 	    (p[1] == '&' && subst != NULL));
   1851 	if (is_escaped) {
   1852 	    Buf_AddByte(&buf, p[1]);
   1853 	    p += 2;
   1854 	    continue;
   1855 	}
   1856 
   1857 	if (*p != '$') {	/* Unescaped, simple text */
   1858 	    if (subst != NULL && *p == '&')
   1859 		Buf_AddBytes(&buf, subst->lhs, subst->lhsLen);
   1860 	    else
   1861 		Buf_AddByte(&buf, *p);
   1862 	    p++;
   1863 	    continue;
   1864 	}
   1865 
   1866 	if (p[1] == delim) {	/* Unescaped $ at end of pattern */
   1867 	    if (out_pflags != NULL)
   1868 		*out_pflags |= VARP_ANCHOR_END;
   1869 	    else
   1870 		Buf_AddByte(&buf, *p);
   1871 	    p++;
   1872 	    continue;
   1873 	}
   1874 
   1875 	if (eflags & VARE_WANTRES) {	/* Nested variable, evaluated */
   1876 	    const char *nested_p = p;
   1877 	    const char *nested_val;
   1878 	    void *nested_val_freeIt;
   1879 	    VarEvalFlags nested_eflags = eflags & ~(unsigned)VARE_ASSIGN;
   1880 
   1881 	    (void)Var_Parse(&nested_p, st->ctxt, nested_eflags,
   1882 			    &nested_val, &nested_val_freeIt);
   1883 	    /* TODO: handle errors */
   1884 	    Buf_AddStr(&buf, nested_val);
   1885 	    free(nested_val_freeIt);
   1886 	    p += nested_p - p;
   1887 	    continue;
   1888 	}
   1889 
   1890 	/* XXX: This whole block is very similar to Var_Parse without
   1891 	 * VARE_WANTRES.  There may be subtle edge cases though that are
   1892 	 * not yet covered in the unit tests and that are parsed differently,
   1893 	 * depending on whether they are evaluated or not.
   1894 	 *
   1895 	 * This subtle difference is not documented in the manual page,
   1896 	 * neither is the difference between parsing :D and :M documented.
   1897 	 * No code should ever depend on these details, but who knows. */
   1898 
   1899 	varstart = p;		/* Nested variable, only parsed */
   1900 	if (p[1] == '(' || p[1] == '{') {
   1901 	    /*
   1902 	     * Find the end of this variable reference
   1903 	     * and suck it in without further ado.
   1904 	     * It will be interpreted later.
   1905 	     */
   1906 	    int have = p[1];
   1907 	    int want = have == '(' ? ')' : '}';
   1908 	    int depth = 1;
   1909 
   1910 	    for (p += 2; *p != '\0' && depth > 0; p++) {
   1911 		if (p[-1] != '\\') {
   1912 		    if (*p == have)
   1913 			depth++;
   1914 		    if (*p == want)
   1915 			depth--;
   1916 		}
   1917 	    }
   1918 	    Buf_AddBytesBetween(&buf, varstart, p);
   1919 	} else {
   1920 	    Buf_AddByte(&buf, *varstart);
   1921 	    p++;
   1922 	}
   1923     }
   1924 
   1925     if (*p != delim) {
   1926 	*pp = p;
   1927 	return NULL;
   1928     }
   1929 
   1930     *pp = ++p;
   1931     if (out_length != NULL)
   1932 	*out_length = Buf_Size(&buf);
   1933 
   1934     rstr = Buf_Destroy(&buf, FALSE);
   1935     VAR_DEBUG("Modifier part: \"%s\"\n", rstr);
   1936     return rstr;
   1937 }
   1938 
   1939 /* Test whether mod starts with modname, followed by a delimiter. */
   1940 static Boolean
   1941 ModMatch(const char *mod, const char *modname, char endc)
   1942 {
   1943     size_t n = strlen(modname);
   1944     return strncmp(mod, modname, n) == 0 &&
   1945 	   (mod[n] == endc || mod[n] == ':');
   1946 }
   1947 
   1948 /* Test whether mod starts with modname, followed by a delimiter or '='. */
   1949 static inline Boolean
   1950 ModMatchEq(const char *mod, const char *modname, char endc)
   1951 {
   1952     size_t n = strlen(modname);
   1953     return strncmp(mod, modname, n) == 0 &&
   1954 	   (mod[n] == endc || mod[n] == ':' || mod[n] == '=');
   1955 }
   1956 
   1957 /* :@var (at) ...${var}...@ */
   1958 static ApplyModifierResult
   1959 ApplyModifier_Loop(const char **pp, ApplyModifiersState *st)
   1960 {
   1961     ModifyWord_LoopArgs args;
   1962     char delim;
   1963     char prev_sep;
   1964     VarEvalFlags eflags = st->eflags & ~(unsigned)VARE_WANTRES;
   1965 
   1966     args.ctx = st->ctxt;
   1967 
   1968     (*pp)++;			/* Skip the first '@' */
   1969     delim = '@';
   1970     args.tvar = ParseModifierPart(pp, delim, eflags, st,
   1971 				  NULL, NULL, NULL);
   1972     if (args.tvar == NULL) {
   1973 	st->missing_delim = delim;
   1974 	return AMR_CLEANUP;
   1975     }
   1976     if (DEBUG(LINT) && strchr(args.tvar, '$') != NULL) {
   1977 	Parse_Error(PARSE_FATAL,
   1978 		    "In the :@ modifier of \"%s\", the variable name \"%s\" "
   1979 		    "must not contain a dollar.",
   1980 		    st->v->name, args.tvar);
   1981 	return AMR_CLEANUP;
   1982     }
   1983 
   1984     args.str = ParseModifierPart(pp, delim, eflags, st,
   1985 				 NULL, NULL, NULL);
   1986     if (args.str == NULL) {
   1987 	st->missing_delim = delim;
   1988 	return AMR_CLEANUP;
   1989     }
   1990 
   1991     args.eflags = st->eflags & (VARE_UNDEFERR | VARE_WANTRES);
   1992     prev_sep = st->sep;
   1993     st->sep = ' ';		/* XXX: should be st->sep for consistency */
   1994     st->newVal = ModifyWords(st->ctxt, st->sep, st->oneBigWord, st->val,
   1995 			     ModifyWord_Loop, &args);
   1996     st->sep = prev_sep;
   1997     Var_Delete(args.tvar, st->ctxt);
   1998     free(args.tvar);
   1999     free(args.str);
   2000     return AMR_OK;
   2001 }
   2002 
   2003 /* :Ddefined or :Uundefined */
   2004 static ApplyModifierResult
   2005 ApplyModifier_Defined(const char **pp, ApplyModifiersState *st)
   2006 {
   2007     Buffer buf;
   2008     const char *p;
   2009 
   2010     VarEvalFlags eflags = st->eflags & ~(unsigned)VARE_WANTRES;
   2011     if (st->eflags & VARE_WANTRES) {
   2012 	if ((**pp == 'D') == !(st->exprFlags & VEF_UNDEF))
   2013 	    eflags |= VARE_WANTRES;
   2014     }
   2015 
   2016     Buf_Init(&buf, 0);
   2017     p = *pp + 1;
   2018     while (*p != st->endc && *p != ':' && *p != '\0') {
   2019 
   2020 	/* Escaped delimiter or other special character */
   2021 	if (*p == '\\') {
   2022 	    char c = p[1];
   2023 	    if (c == st->endc || c == ':' || c == '$' || c == '\\') {
   2024 		Buf_AddByte(&buf, c);
   2025 		p += 2;
   2026 		continue;
   2027 	    }
   2028 	}
   2029 
   2030 	/* Nested variable expression */
   2031 	if (*p == '$') {
   2032 	    const char *nested_val;
   2033 	    void *nested_val_freeIt;
   2034 
   2035 	    (void)Var_Parse(&p, st->ctxt, eflags,
   2036 			    &nested_val, &nested_val_freeIt);
   2037 	    /* TODO: handle errors */
   2038 	    Buf_AddStr(&buf, nested_val);
   2039 	    free(nested_val_freeIt);
   2040 	    continue;
   2041 	}
   2042 
   2043 	/* Ordinary text */
   2044 	Buf_AddByte(&buf, *p);
   2045 	p++;
   2046     }
   2047     *pp = p;
   2048 
   2049     ApplyModifiersState_Define(st);
   2050 
   2051     if (eflags & VARE_WANTRES) {
   2052 	st->newVal = Buf_Destroy(&buf, FALSE);
   2053     } else {
   2054 	st->newVal = st->val;
   2055 	Buf_Destroy(&buf, TRUE);
   2056     }
   2057     return AMR_OK;
   2058 }
   2059 
   2060 /* :gmtime */
   2061 static ApplyModifierResult
   2062 ApplyModifier_Gmtime(const char **pp, ApplyModifiersState *st)
   2063 {
   2064     time_t utc;
   2065 
   2066     const char *mod = *pp;
   2067     if (!ModMatchEq(mod, "gmtime", st->endc))
   2068 	return AMR_UNKNOWN;
   2069 
   2070     if (mod[6] == '=') {
   2071 	char *ep;
   2072 	utc = (time_t)strtoul(mod + 7, &ep, 10);
   2073 	*pp = ep;
   2074     } else {
   2075 	utc = 0;
   2076 	*pp = mod + 6;
   2077     }
   2078     st->newVal = VarStrftime(st->val, TRUE, utc);
   2079     return AMR_OK;
   2080 }
   2081 
   2082 /* :localtime */
   2083 static ApplyModifierResult
   2084 ApplyModifier_Localtime(const char **pp, ApplyModifiersState *st)
   2085 {
   2086     time_t utc;
   2087 
   2088     const char *mod = *pp;
   2089     if (!ModMatchEq(mod, "localtime", st->endc))
   2090 	return AMR_UNKNOWN;
   2091 
   2092     if (mod[9] == '=') {
   2093 	char *ep;
   2094 	utc = (time_t)strtoul(mod + 10, &ep, 10);
   2095 	*pp = ep;
   2096     } else {
   2097 	utc = 0;
   2098 	*pp = mod + 9;
   2099     }
   2100     st->newVal = VarStrftime(st->val, FALSE, utc);
   2101     return AMR_OK;
   2102 }
   2103 
   2104 /* :hash */
   2105 static ApplyModifierResult
   2106 ApplyModifier_Hash(const char **pp, ApplyModifiersState *st)
   2107 {
   2108     if (!ModMatch(*pp, "hash", st->endc))
   2109 	return AMR_UNKNOWN;
   2110 
   2111     st->newVal = VarHash(st->val);
   2112     *pp += 4;
   2113     return AMR_OK;
   2114 }
   2115 
   2116 /* :P */
   2117 static ApplyModifierResult
   2118 ApplyModifier_Path(const char **pp, ApplyModifiersState *st)
   2119 {
   2120     GNode *gn;
   2121     char *path;
   2122 
   2123     ApplyModifiersState_Define(st);
   2124 
   2125     gn = Targ_FindNode(st->v->name, TARG_NOCREATE);
   2126     if (gn == NULL || gn->type & OP_NOPATH) {
   2127 	path = NULL;
   2128     } else if (gn->path) {
   2129 	path = bmake_strdup(gn->path);
   2130     } else {
   2131 	SearchPath *searchPath = Suff_FindPath(gn);
   2132 	path = Dir_FindFile(st->v->name, searchPath);
   2133     }
   2134     if (path == NULL)
   2135 	path = bmake_strdup(st->v->name);
   2136     st->newVal = path;
   2137 
   2138     (*pp)++;
   2139     return AMR_OK;
   2140 }
   2141 
   2142 /* :!cmd! */
   2143 static ApplyModifierResult
   2144 ApplyModifier_ShellCommand(const char **pp, ApplyModifiersState *st)
   2145 {
   2146     char delim;
   2147     char *cmd;
   2148     const char *errfmt;
   2149 
   2150     (*pp)++;
   2151     delim = '!';
   2152     cmd = ParseModifierPart(pp, delim, st->eflags, st,
   2153 			    NULL, NULL, NULL);
   2154     if (cmd == NULL) {
   2155 	st->missing_delim = delim;
   2156 	return AMR_CLEANUP;
   2157     }
   2158 
   2159     errfmt = NULL;
   2160     if (st->eflags & VARE_WANTRES)
   2161 	st->newVal = Cmd_Exec(cmd, &errfmt);
   2162     else
   2163 	st->newVal = varNoError;
   2164     free(cmd);
   2165 
   2166     if (errfmt != NULL)
   2167 	Error(errfmt, st->val);	/* XXX: why still return AMR_OK? */
   2168 
   2169     ApplyModifiersState_Define(st);
   2170     return AMR_OK;
   2171 }
   2172 
   2173 /* The :range modifier generates an integer sequence as long as the words.
   2174  * The :range=7 modifier generates an integer sequence from 1 to 7. */
   2175 static ApplyModifierResult
   2176 ApplyModifier_Range(const char **pp, ApplyModifiersState *st)
   2177 {
   2178     size_t n;
   2179     Buffer buf;
   2180     size_t i;
   2181 
   2182     const char *mod = *pp;
   2183     if (!ModMatchEq(mod, "range", st->endc))
   2184 	return AMR_UNKNOWN;
   2185 
   2186     if (mod[5] == '=') {
   2187 	char *ep;
   2188 	n = (size_t)strtoul(mod + 6, &ep, 10);
   2189 	*pp = ep;
   2190     } else {
   2191 	n = 0;
   2192 	*pp = mod + 5;
   2193     }
   2194 
   2195     if (n == 0) {
   2196 	Words words = Str_Words(st->val, FALSE);
   2197 	n = words.len;
   2198 	Words_Free(words);
   2199     }
   2200 
   2201     Buf_Init(&buf, 0);
   2202 
   2203     for (i = 0; i < n; i++) {
   2204 	if (i != 0)
   2205 	    Buf_AddByte(&buf, ' ');	/* XXX: st->sep, for consistency */
   2206 	Buf_AddInt(&buf, 1 + (int)i);
   2207     }
   2208 
   2209     st->newVal = Buf_Destroy(&buf, FALSE);
   2210     return AMR_OK;
   2211 }
   2212 
   2213 /* :Mpattern or :Npattern */
   2214 static ApplyModifierResult
   2215 ApplyModifier_Match(const char **pp, ApplyModifiersState *st)
   2216 {
   2217     const char *mod = *pp;
   2218     Boolean copy = FALSE;	/* pattern should be, or has been, copied */
   2219     Boolean needSubst = FALSE;
   2220     const char *endpat;
   2221     char *pattern;
   2222     ModifyWordsCallback callback;
   2223 
   2224     /*
   2225      * In the loop below, ignore ':' unless we are at (or back to) the
   2226      * original brace level.
   2227      * XXX This will likely not work right if $() and ${} are intermixed.
   2228      */
   2229     int nest = 0;
   2230     const char *p;
   2231     for (p = mod + 1; *p != '\0' && !(*p == ':' && nest == 0); p++) {
   2232 	if (*p == '\\' &&
   2233 	    (p[1] == ':' || p[1] == st->endc || p[1] == st->startc)) {
   2234 	    if (!needSubst)
   2235 		copy = TRUE;
   2236 	    p++;
   2237 	    continue;
   2238 	}
   2239 	if (*p == '$')
   2240 	    needSubst = TRUE;
   2241 	if (*p == '(' || *p == '{')
   2242 	    nest++;
   2243 	if (*p == ')' || *p == '}') {
   2244 	    nest--;
   2245 	    if (nest < 0)
   2246 		break;
   2247 	}
   2248     }
   2249     *pp = p;
   2250     endpat = p;
   2251 
   2252     if (copy) {
   2253 	char *dst;
   2254 	const char *src;
   2255 
   2256 	/* Compress the \:'s out of the pattern. */
   2257 	pattern = bmake_malloc((size_t)(endpat - (mod + 1)) + 1);
   2258 	dst = pattern;
   2259 	src = mod + 1;
   2260 	for (; src < endpat; src++, dst++) {
   2261 	    if (src[0] == '\\' && src + 1 < endpat &&
   2262 		/* XXX: st->startc is missing here; see above */
   2263 		(src[1] == ':' || src[1] == st->endc))
   2264 		src++;
   2265 	    *dst = *src;
   2266 	}
   2267 	*dst = '\0';
   2268 	endpat = dst;
   2269     } else {
   2270 	pattern = bmake_strsedup(mod + 1, endpat);
   2271     }
   2272 
   2273     if (needSubst) {
   2274 	/* pattern contains embedded '$', so use Var_Subst to expand it. */
   2275 	char *old_pattern = pattern;
   2276 	pattern = Var_Subst(pattern, st->ctxt, st->eflags);
   2277 	free(old_pattern);
   2278     }
   2279 
   2280     VAR_DEBUG("Pattern[%s] for [%s] is [%s]\n", st->v->name, st->val, pattern);
   2281 
   2282     callback = mod[0] == 'M' ? ModifyWord_Match : ModifyWord_NoMatch;
   2283     st->newVal = ModifyWords(st->ctxt, st->sep, st->oneBigWord, st->val,
   2284 			     callback, pattern);
   2285     free(pattern);
   2286     return AMR_OK;
   2287 }
   2288 
   2289 /* :S,from,to, */
   2290 static ApplyModifierResult
   2291 ApplyModifier_Subst(const char **pp, ApplyModifiersState *st)
   2292 {
   2293     ModifyWord_SubstArgs args;
   2294     char *lhs, *rhs;
   2295     Boolean oneBigWord;
   2296 
   2297     char delim = (*pp)[1];
   2298     if (delim == '\0') {
   2299 	Error("Missing delimiter for :S modifier");
   2300 	(*pp)++;
   2301 	return AMR_CLEANUP;
   2302     }
   2303 
   2304     *pp += 2;
   2305 
   2306     args.pflags = 0;
   2307     args.matched = FALSE;
   2308 
   2309     /*
   2310      * If pattern begins with '^', it is anchored to the
   2311      * start of the word -- skip over it and flag pattern.
   2312      */
   2313     if (**pp == '^') {
   2314 	args.pflags |= VARP_ANCHOR_START;
   2315 	(*pp)++;
   2316     }
   2317 
   2318     lhs = ParseModifierPart(pp, delim, st->eflags, st,
   2319 			    &args.lhsLen, &args.pflags, NULL);
   2320     if (lhs == NULL) {
   2321 	st->missing_delim = delim;
   2322 	return AMR_CLEANUP;
   2323     }
   2324     args.lhs = lhs;
   2325 
   2326     rhs = ParseModifierPart(pp, delim, st->eflags, st,
   2327 			    &args.rhsLen, NULL, &args);
   2328     if (rhs == NULL) {
   2329 	st->missing_delim = delim;
   2330 	return AMR_CLEANUP;
   2331     }
   2332     args.rhs = rhs;
   2333 
   2334     oneBigWord = st->oneBigWord;
   2335     for (;; (*pp)++) {
   2336 	switch (**pp) {
   2337 	case 'g':
   2338 	    args.pflags |= VARP_SUB_GLOBAL;
   2339 	    continue;
   2340 	case '1':
   2341 	    args.pflags |= VARP_SUB_ONE;
   2342 	    continue;
   2343 	case 'W':
   2344 	    oneBigWord = TRUE;
   2345 	    continue;
   2346 	}
   2347 	break;
   2348     }
   2349 
   2350     st->newVal = ModifyWords(st->ctxt, st->sep, oneBigWord, st->val,
   2351 			     ModifyWord_Subst, &args);
   2352 
   2353     free(lhs);
   2354     free(rhs);
   2355     return AMR_OK;
   2356 }
   2357 
   2358 #ifndef NO_REGEX
   2359 
   2360 /* :C,from,to, */
   2361 static ApplyModifierResult
   2362 ApplyModifier_Regex(const char **pp, ApplyModifiersState *st)
   2363 {
   2364     char *re;
   2365     ModifyWord_SubstRegexArgs args;
   2366     Boolean oneBigWord;
   2367     int error;
   2368 
   2369     char delim = (*pp)[1];
   2370     if (delim == '\0') {
   2371 	Error("Missing delimiter for :C modifier");
   2372 	(*pp)++;
   2373 	return AMR_CLEANUP;
   2374     }
   2375 
   2376     *pp += 2;
   2377 
   2378     re = ParseModifierPart(pp, delim, st->eflags, st,
   2379 			   NULL, NULL, NULL);
   2380     if (re == NULL) {
   2381 	st->missing_delim = delim;
   2382 	return AMR_CLEANUP;
   2383     }
   2384 
   2385     args.replace = ParseModifierPart(pp, delim, st->eflags, st,
   2386 				     NULL, NULL, NULL);
   2387     if (args.replace == NULL) {
   2388 	free(re);
   2389 	st->missing_delim = delim;
   2390 	return AMR_CLEANUP;
   2391     }
   2392 
   2393     args.pflags = 0;
   2394     args.matched = FALSE;
   2395     oneBigWord = st->oneBigWord;
   2396     for (;; (*pp)++) {
   2397 	switch (**pp) {
   2398 	case 'g':
   2399 	    args.pflags |= VARP_SUB_GLOBAL;
   2400 	    continue;
   2401 	case '1':
   2402 	    args.pflags |= VARP_SUB_ONE;
   2403 	    continue;
   2404 	case 'W':
   2405 	    oneBigWord = TRUE;
   2406 	    continue;
   2407 	}
   2408 	break;
   2409     }
   2410 
   2411     error = regcomp(&args.re, re, REG_EXTENDED);
   2412     free(re);
   2413     if (error) {
   2414 	VarREError(error, &args.re, "Regex compilation error");
   2415 	free(args.replace);
   2416 	return AMR_CLEANUP;
   2417     }
   2418 
   2419     args.nsub = args.re.re_nsub + 1;
   2420     if (args.nsub > 10)
   2421 	args.nsub = 10;
   2422     st->newVal = ModifyWords(st->ctxt, st->sep, oneBigWord, st->val,
   2423 			     ModifyWord_SubstRegex, &args);
   2424     regfree(&args.re);
   2425     free(args.replace);
   2426     return AMR_OK;
   2427 }
   2428 #endif
   2429 
   2430 static void
   2431 ModifyWord_Copy(const char *word, SepBuf *buf, void *data MAKE_ATTR_UNUSED)
   2432 {
   2433     SepBuf_AddStr(buf, word);
   2434 }
   2435 
   2436 /* :ts<separator> */
   2437 static ApplyModifierResult
   2438 ApplyModifier_ToSep(const char **pp, ApplyModifiersState *st)
   2439 {
   2440     /* XXX: pp points to the 's', for historic reasons only.
   2441      * Changing this will influence the error messages. */
   2442     const char *sep = *pp + 1;
   2443 
   2444     /* ":ts<any><endc>" or ":ts<any>:" */
   2445     if (sep[0] != st->endc && (sep[1] == st->endc || sep[1] == ':')) {
   2446 	st->sep = sep[0];
   2447 	*pp = sep + 1;
   2448 	goto ok;
   2449     }
   2450 
   2451     /* ":ts<endc>" or ":ts:" */
   2452     if (sep[0] == st->endc || sep[0] == ':') {
   2453 	st->sep = '\0';		/* no separator */
   2454 	*pp = sep;
   2455 	goto ok;
   2456     }
   2457 
   2458     /* ":ts<unrecognised><unrecognised>". */
   2459     if (sep[0] != '\\')
   2460 	return AMR_BAD;
   2461 
   2462     /* ":ts\n" */
   2463     if (sep[1] == 'n') {
   2464 	st->sep = '\n';
   2465 	*pp = sep + 2;
   2466 	goto ok;
   2467     }
   2468 
   2469     /* ":ts\t" */
   2470     if (sep[1] == 't') {
   2471 	st->sep = '\t';
   2472 	*pp = sep + 2;
   2473 	goto ok;
   2474     }
   2475 
   2476     /* ":ts\x40" or ":ts\100" */
   2477     {
   2478 	const char *numStart = sep + 1;
   2479 	int base = 8;		/* assume octal */
   2480 	char *end;
   2481 
   2482 	if (sep[1] == 'x') {
   2483 	    base = 16;
   2484 	    numStart++;
   2485 	} else if (!ch_isdigit(sep[1]))
   2486 	    return AMR_BAD;	/* ":ts<backslash><unrecognised>". */
   2487 
   2488 	st->sep = (char)strtoul(numStart, &end, base);
   2489 	if (*end != ':' && *end != st->endc)
   2490 	    return AMR_BAD;
   2491 	*pp = end;
   2492     }
   2493 
   2494 ok:
   2495     st->newVal = ModifyWords(st->ctxt, st->sep, st->oneBigWord, st->val,
   2496 			     ModifyWord_Copy, NULL);
   2497     return AMR_OK;
   2498 }
   2499 
   2500 /* :tA, :tu, :tl, :ts<separator>, etc. */
   2501 static ApplyModifierResult
   2502 ApplyModifier_To(const char **pp, ApplyModifiersState *st)
   2503 {
   2504     const char *mod = *pp;
   2505     assert(mod[0] == 't');
   2506 
   2507     *pp = mod + 1;		/* make sure it is set */
   2508     if (mod[1] == st->endc || mod[1] == ':' || mod[1] == '\0')
   2509 	return AMR_BAD;		/* Found ":t<endc>" or ":t:". */
   2510 
   2511     if (mod[1] == 's')
   2512 	return ApplyModifier_ToSep(pp, st);
   2513 
   2514     if (mod[2] != st->endc && mod[2] != ':')
   2515 	return AMR_BAD;		/* Found ":t<unrecognised><unrecognised>". */
   2516 
   2517     /* Check for two-character options: ":tu", ":tl" */
   2518     if (mod[1] == 'A') {	/* absolute path */
   2519 	st->newVal = ModifyWords(st->ctxt, st->sep, st->oneBigWord, st->val,
   2520 				 ModifyWord_Realpath, NULL);
   2521 	*pp = mod + 2;
   2522 	return AMR_OK;
   2523     }
   2524 
   2525     if (mod[1] == 'u') {
   2526 	size_t i;
   2527 	size_t len = strlen(st->val);
   2528 	st->newVal = bmake_malloc(len + 1);
   2529 	for (i = 0; i < len + 1; i++)
   2530 	    st->newVal[i] = ch_toupper(st->val[i]);
   2531 	*pp = mod + 2;
   2532 	return AMR_OK;
   2533     }
   2534 
   2535     if (mod[1] == 'l') {
   2536 	size_t i;
   2537 	size_t len = strlen(st->val);
   2538 	st->newVal = bmake_malloc(len + 1);
   2539 	for (i = 0; i < len + 1; i++)
   2540 	    st->newVal[i] = ch_tolower(st->val[i]);
   2541 	*pp = mod + 2;
   2542 	return AMR_OK;
   2543     }
   2544 
   2545     if (mod[1] == 'W' || mod[1] == 'w') {
   2546 	st->oneBigWord = mod[1] == 'W';
   2547 	st->newVal = st->val;
   2548 	*pp = mod + 2;
   2549 	return AMR_OK;
   2550     }
   2551 
   2552     /* Found ":t<unrecognised>:" or ":t<unrecognised><endc>". */
   2553     return AMR_BAD;
   2554 }
   2555 
   2556 /* :[#], :[1], etc. */
   2557 static ApplyModifierResult
   2558 ApplyModifier_Words(const char **pp, ApplyModifiersState *st)
   2559 {
   2560     char delim;
   2561     char *estr;
   2562     char *ep;
   2563     int first, last;
   2564 
   2565     (*pp)++;			/* skip the '[' */
   2566     delim = ']';		/* look for closing ']' */
   2567     estr = ParseModifierPart(pp, delim, st->eflags, st,
   2568 			     NULL, NULL, NULL);
   2569     if (estr == NULL) {
   2570 	st->missing_delim = delim;
   2571 	return AMR_CLEANUP;
   2572     }
   2573 
   2574     /* now *pp points just after the closing ']' */
   2575     if (**pp != ':' && **pp != st->endc)
   2576 	goto bad_modifier;	/* Found junk after ']' */
   2577 
   2578     if (estr[0] == '\0')
   2579 	goto bad_modifier;	/* empty square brackets in ":[]". */
   2580 
   2581     if (estr[0] == '#' && estr[1] == '\0') { /* Found ":[#]" */
   2582 	if (st->oneBigWord) {
   2583 	    st->newVal = bmake_strdup("1");
   2584 	} else {
   2585 	    Buffer buf;
   2586 
   2587 	    Words words = Str_Words(st->val, FALSE);
   2588 	    size_t ac = words.len;
   2589 	    Words_Free(words);
   2590 
   2591 	    Buf_Init(&buf, 4);	/* 3 digits + '\0' is usually enough */
   2592 	    Buf_AddInt(&buf, (int)ac);
   2593 	    st->newVal = Buf_Destroy(&buf, FALSE);
   2594 	}
   2595 	goto ok;
   2596     }
   2597 
   2598     if (estr[0] == '*' && estr[1] == '\0') {
   2599 	/* Found ":[*]" */
   2600 	st->oneBigWord = TRUE;
   2601 	st->newVal = st->val;
   2602 	goto ok;
   2603     }
   2604 
   2605     if (estr[0] == '@' && estr[1] == '\0') {
   2606 	/* Found ":[@]" */
   2607 	st->oneBigWord = FALSE;
   2608 	st->newVal = st->val;
   2609 	goto ok;
   2610     }
   2611 
   2612     /*
   2613      * We expect estr to contain a single integer for :[N], or two integers
   2614      * separated by ".." for :[start..end].
   2615      */
   2616     first = (int)strtol(estr, &ep, 0);
   2617     if (ep == estr)		/* Found junk instead of a number */
   2618 	goto bad_modifier;
   2619 
   2620     if (ep[0] == '\0') {	/* Found only one integer in :[N] */
   2621 	last = first;
   2622     } else if (ep[0] == '.' && ep[1] == '.' && ep[2] != '\0') {
   2623 	/* Expecting another integer after ".." */
   2624 	ep += 2;
   2625 	last = (int)strtol(ep, &ep, 0);
   2626 	if (ep[0] != '\0')	/* Found junk after ".." */
   2627 	    goto bad_modifier;
   2628     } else
   2629 	goto bad_modifier;	/* Found junk instead of ".." */
   2630 
   2631     /*
   2632      * Now seldata is properly filled in, but we still have to check for 0 as
   2633      * a special case.
   2634      */
   2635     if (first == 0 && last == 0) {
   2636 	/* ":[0]" or perhaps ":[0..0]" */
   2637 	st->oneBigWord = TRUE;
   2638 	st->newVal = st->val;
   2639 	goto ok;
   2640     }
   2641 
   2642     /* ":[0..N]" or ":[N..0]" */
   2643     if (first == 0 || last == 0)
   2644 	goto bad_modifier;
   2645 
   2646     /* Normal case: select the words described by seldata. */
   2647     st->newVal = VarSelectWords(st->sep, st->oneBigWord, st->val, first, last);
   2648 
   2649 ok:
   2650     free(estr);
   2651     return AMR_OK;
   2652 
   2653 bad_modifier:
   2654     free(estr);
   2655     return AMR_BAD;
   2656 }
   2657 
   2658 static int
   2659 str_cmp_asc(const void *a, const void *b)
   2660 {
   2661     return strcmp(*(const char * const *)a, *(const char * const *)b);
   2662 }
   2663 
   2664 static int
   2665 str_cmp_desc(const void *a, const void *b)
   2666 {
   2667     return strcmp(*(const char * const *)b, *(const char * const *)a);
   2668 }
   2669 
   2670 /* :O (order ascending) or :Or (order descending) or :Ox (shuffle) */
   2671 static ApplyModifierResult
   2672 ApplyModifier_Order(const char **pp, ApplyModifiersState *st)
   2673 {
   2674     const char *mod = (*pp)++;	/* skip past the 'O' in any case */
   2675 
   2676     Words words = Str_Words(st->val, FALSE);
   2677 
   2678     if (mod[1] == st->endc || mod[1] == ':') {
   2679 	/* :O sorts ascending */
   2680 	qsort(words.words, words.len, sizeof(char *), str_cmp_asc);
   2681 
   2682     } else if ((mod[1] == 'r' || mod[1] == 'x') &&
   2683 	       (mod[2] == st->endc || mod[2] == ':')) {
   2684 	(*pp)++;
   2685 
   2686 	if (mod[1] == 'r') {
   2687 	    /* :Or sorts descending */
   2688 	    qsort(words.words, words.len, sizeof(char *), str_cmp_desc);
   2689 
   2690 	} else {
   2691 	    /* :Ox shuffles
   2692 	     *
   2693 	     * We will use [ac..2] range for mod factors. This will produce
   2694 	     * random numbers in [(ac-1)..0] interval, and minimal
   2695 	     * reasonable value for mod factor is 2 (the mod 1 will produce
   2696 	     * 0 with probability 1).
   2697 	     */
   2698 	    size_t i;
   2699 	    for (i = words.len - 1; i > 0; i--) {
   2700 		size_t rndidx = (size_t)random() % (i + 1);
   2701 		char *t = words.words[i];
   2702 		words.words[i] = words.words[rndidx];
   2703 		words.words[rndidx] = t;
   2704 	    }
   2705 	}
   2706     } else {
   2707 	Words_Free(words);
   2708 	return AMR_BAD;
   2709     }
   2710 
   2711     st->newVal = Words_JoinFree(words);
   2712     return AMR_OK;
   2713 }
   2714 
   2715 /* :? then : else */
   2716 static ApplyModifierResult
   2717 ApplyModifier_IfElse(const char **pp, ApplyModifiersState *st)
   2718 {
   2719     char delim;
   2720     char *then_expr, *else_expr;
   2721 
   2722     Boolean value = FALSE;
   2723     VarEvalFlags then_eflags = st->eflags & ~(unsigned)VARE_WANTRES;
   2724     VarEvalFlags else_eflags = st->eflags & ~(unsigned)VARE_WANTRES;
   2725 
   2726     int cond_rc = COND_PARSE;	/* anything other than COND_INVALID */
   2727     if (st->eflags & VARE_WANTRES) {
   2728 	cond_rc = Cond_EvalCondition(st->v->name, &value);
   2729 	if (cond_rc != COND_INVALID && value)
   2730 	    then_eflags |= VARE_WANTRES;
   2731 	if (cond_rc != COND_INVALID && !value)
   2732 	    else_eflags |= VARE_WANTRES;
   2733     }
   2734 
   2735     (*pp)++;			/* skip past the '?' */
   2736     delim = ':';
   2737     then_expr = ParseModifierPart(pp, delim, then_eflags, st,
   2738 				  NULL, NULL, NULL);
   2739     if (then_expr == NULL) {
   2740 	st->missing_delim = delim;
   2741 	return AMR_CLEANUP;
   2742     }
   2743 
   2744     delim = st->endc;		/* BRCLOSE or PRCLOSE */
   2745     else_expr = ParseModifierPart(pp, delim, else_eflags, st,
   2746 				  NULL, NULL, NULL);
   2747     if (else_expr == NULL) {
   2748 	st->missing_delim = delim;
   2749 	return AMR_CLEANUP;
   2750     }
   2751 
   2752     (*pp)--;
   2753     if (cond_rc == COND_INVALID) {
   2754 	Error("Bad conditional expression `%s' in %s?%s:%s",
   2755 	      st->v->name, st->v->name, then_expr, else_expr);
   2756 	return AMR_CLEANUP;
   2757     }
   2758 
   2759     if (value) {
   2760 	st->newVal = then_expr;
   2761 	free(else_expr);
   2762     } else {
   2763 	st->newVal = else_expr;
   2764 	free(then_expr);
   2765     }
   2766     ApplyModifiersState_Define(st);
   2767     return AMR_OK;
   2768 }
   2769 
   2770 /*
   2771  * The ::= modifiers actually assign a value to the variable.
   2772  * Their main purpose is in supporting modifiers of .for loop
   2773  * iterators and other obscure uses.  They always expand to
   2774  * nothing.  In a target rule that would otherwise expand to an
   2775  * empty line they can be preceded with @: to keep make happy.
   2776  * Eg.
   2777  *
   2778  * foo:	.USE
   2779  * .for i in ${.TARGET} ${.TARGET:R}.gz
   2780  * 	@: ${t::=$i}
   2781  *	@echo blah ${t:T}
   2782  * .endfor
   2783  *
   2784  *	  ::=<str>	Assigns <str> as the new value of variable.
   2785  *	  ::?=<str>	Assigns <str> as value of variable if
   2786  *			it was not already set.
   2787  *	  ::+=<str>	Appends <str> to variable.
   2788  *	  ::!=<cmd>	Assigns output of <cmd> as the new value of
   2789  *			variable.
   2790  */
   2791 static ApplyModifierResult
   2792 ApplyModifier_Assign(const char **pp, ApplyModifiersState *st)
   2793 {
   2794     GNode *v_ctxt;
   2795     char *sv_name;
   2796     char delim;
   2797     char *val;
   2798 
   2799     const char *mod = *pp;
   2800     const char *op = mod + 1;
   2801     if (!(op[0] == '=' ||
   2802 	  (op[1] == '=' &&
   2803 	   (op[0] == '!' || op[0] == '+' || op[0] == '?'))))
   2804 	return AMR_UNKNOWN;	/* "::<unrecognised>" */
   2805 
   2806 
   2807     if (st->v->name[0] == 0) {
   2808 	*pp = mod + 1;
   2809 	return AMR_BAD;
   2810     }
   2811 
   2812     v_ctxt = st->ctxt;		/* context where v belongs */
   2813     sv_name = NULL;
   2814     if (st->exprFlags & VEF_UNDEF) {
   2815 	/*
   2816 	 * We need to bmake_strdup() it in case ParseModifierPart() recurses.
   2817 	 */
   2818 	sv_name = st->v->name;
   2819 	st->v->name = bmake_strdup(st->v->name);
   2820     } else if (st->ctxt != VAR_GLOBAL) {
   2821 	Var *gv = VarFind(st->v->name, st->ctxt, 0);
   2822 	if (gv == NULL)
   2823 	    v_ctxt = VAR_GLOBAL;
   2824 	else
   2825 	    VarFreeEnv(gv, TRUE);
   2826     }
   2827 
   2828     switch (op[0]) {
   2829     case '+':
   2830     case '?':
   2831     case '!':
   2832 	*pp = mod + 3;
   2833 	break;
   2834     default:
   2835 	*pp = mod + 2;
   2836 	break;
   2837     }
   2838 
   2839     delim = st->startc == '(' ? ')' : '}';
   2840     val = ParseModifierPart(pp, delim, st->eflags, st, NULL, NULL, NULL);
   2841     if (st->exprFlags & VEF_UNDEF) {
   2842 	/* restore original name */
   2843 	free(st->v->name);
   2844 	st->v->name = sv_name;
   2845     }
   2846     if (val == NULL) {
   2847 	st->missing_delim = delim;
   2848 	return AMR_CLEANUP;
   2849     }
   2850 
   2851     (*pp)--;
   2852 
   2853     if (st->eflags & VARE_WANTRES) {
   2854 	switch (op[0]) {
   2855 	case '+':
   2856 	    Var_Append(st->v->name, val, v_ctxt);
   2857 	    break;
   2858 	case '!': {
   2859 	    const char *errfmt;
   2860 	    char *cmd_output = Cmd_Exec(val, &errfmt);
   2861 	    if (errfmt)
   2862 		Error(errfmt, val);
   2863 	    else
   2864 		Var_Set(st->v->name, cmd_output, v_ctxt);
   2865 	    free(cmd_output);
   2866 	    break;
   2867 	}
   2868 	case '?':
   2869 	    if (!(st->exprFlags & VEF_UNDEF))
   2870 		break;
   2871 	    /* FALLTHROUGH */
   2872 	default:
   2873 	    Var_Set(st->v->name, val, v_ctxt);
   2874 	    break;
   2875 	}
   2876     }
   2877     free(val);
   2878     st->newVal = varNoError;	/* XXX: varNoError is kind of an error,
   2879 				 * the intention here is to just return
   2880 				 * an empty string. */
   2881     return AMR_OK;
   2882 }
   2883 
   2884 /* remember current value */
   2885 static ApplyModifierResult
   2886 ApplyModifier_Remember(const char **pp, ApplyModifiersState *st)
   2887 {
   2888     const char *mod = *pp;
   2889     if (!ModMatchEq(mod, "_", st->endc))
   2890 	return AMR_UNKNOWN;
   2891 
   2892     if (mod[1] == '=') {
   2893 	size_t n = strcspn(mod + 2, ":)}");
   2894 	char *name = bmake_strldup(mod + 2, n);
   2895 	Var_Set(name, st->val, st->ctxt);
   2896 	free(name);
   2897 	*pp = mod + 2 + n;
   2898     } else {
   2899 	Var_Set("_", st->val, st->ctxt);
   2900 	*pp = mod + 1;
   2901     }
   2902     st->newVal = st->val;
   2903     return AMR_OK;
   2904 }
   2905 
   2906 /* Apply the given function to each word of the variable value. */
   2907 static ApplyModifierResult
   2908 ApplyModifier_WordFunc(const char **pp, ApplyModifiersState *st,
   2909 		       ModifyWordsCallback modifyWord)
   2910 {
   2911     char delim = (*pp)[1];
   2912     if (delim != st->endc && delim != ':')
   2913 	return AMR_UNKNOWN;
   2914 
   2915     st->newVal = ModifyWords(st->ctxt, st->sep, st->oneBigWord,
   2916 			    st->val, modifyWord, NULL);
   2917     (*pp)++;
   2918     return AMR_OK;
   2919 }
   2920 
   2921 #ifdef SYSVVARSUB
   2922 /* :from=to */
   2923 static ApplyModifierResult
   2924 ApplyModifier_SysV(const char **pp, ApplyModifiersState *st)
   2925 {
   2926     char delim;
   2927     char *lhs, *rhs;
   2928 
   2929     const char *mod = *pp;
   2930     Boolean eqFound = FALSE;
   2931 
   2932     /*
   2933      * First we make a pass through the string trying
   2934      * to verify it is a SYSV-make-style translation:
   2935      * it must be: <string1>=<string2>)
   2936      */
   2937     int nest = 1;
   2938     const char *next = mod;
   2939     while (*next != '\0' && nest > 0) {
   2940 	if (*next == '=') {
   2941 	    eqFound = TRUE;
   2942 	    /* continue looking for st->endc */
   2943 	} else if (*next == st->endc)
   2944 	    nest--;
   2945 	else if (*next == st->startc)
   2946 	    nest++;
   2947 	if (nest > 0)
   2948 	    next++;
   2949     }
   2950     if (*next != st->endc || !eqFound)
   2951 	return AMR_UNKNOWN;
   2952 
   2953     delim = '=';
   2954     *pp = mod;
   2955     lhs = ParseModifierPart(pp, delim, st->eflags, st, NULL, NULL, NULL);
   2956     if (lhs == NULL) {
   2957 	st->missing_delim = delim;
   2958 	return AMR_CLEANUP;
   2959     }
   2960 
   2961     delim = st->endc;
   2962     rhs = ParseModifierPart(pp, delim, st->eflags, st, NULL, NULL, NULL);
   2963     if (rhs == NULL) {
   2964 	st->missing_delim = delim;
   2965 	return AMR_CLEANUP;
   2966     }
   2967 
   2968     /*
   2969      * SYSV modifications happen through the whole
   2970      * string. Note the pattern is anchored at the end.
   2971      */
   2972     (*pp)--;
   2973     if (lhs[0] == '\0' && st->val[0] == '\0') {
   2974 	st->newVal = st->val;	/* special case */
   2975     } else {
   2976 	ModifyWord_SYSVSubstArgs args = {st->ctxt, lhs, rhs};
   2977 	st->newVal = ModifyWords(st->ctxt, st->sep, st->oneBigWord, st->val,
   2978 				 ModifyWord_SYSVSubst, &args);
   2979     }
   2980     free(lhs);
   2981     free(rhs);
   2982     return AMR_OK;
   2983 }
   2984 #endif
   2985 
   2986 /* Apply any modifiers (such as :Mpattern or :@var@loop@ or :Q or ::=value). */
   2987 static char *
   2988 ApplyModifiers(
   2989     const char **pp,		/* the parsing position, updated upon return */
   2990     char *val,			/* the current value of the variable */
   2991     char const startc,		/* '(' or '{', or '\0' for indirect modifiers */
   2992     char const endc,		/* ')' or '}', or '\0' for indirect modifiers */
   2993     Var * const v,
   2994     VarExprFlags *exprFlags,
   2995     GNode * const ctxt,		/* for looking up and modifying variables */
   2996     VarEvalFlags const eflags,
   2997     void ** const freePtr	/* free this after using the return value */
   2998 ) {
   2999     ApplyModifiersState st = {
   3000 	startc, endc, v, ctxt, eflags, val,
   3001 	var_Error,		/* .newVal */
   3002 	'\0',			/* .missing_delim */
   3003 	' ',			/* .sep */
   3004 	FALSE,			/* .oneBigWord */
   3005 	*exprFlags		/* .exprFlags */
   3006     };
   3007     const char *p;
   3008     const char *mod;
   3009     ApplyModifierResult res;
   3010 
   3011     assert(startc == '(' || startc == '{' || startc == '\0');
   3012     assert(endc == ')' || endc == '}' || endc == '\0');
   3013     assert(val != NULL);
   3014 
   3015     p = *pp;
   3016     while (*p != '\0' && *p != endc) {
   3017 
   3018 	if (*p == '$') {
   3019 	    /*
   3020 	     * We may have some complex modifiers in a variable.
   3021 	     */
   3022 	    const char *nested_p = p;
   3023 	    void *freeIt;
   3024 	    const char *rval;
   3025 	    int c;
   3026 
   3027 	    (void)Var_Parse(&nested_p, st.ctxt, st.eflags, &rval, &freeIt);
   3028 	    /* TODO: handle errors */
   3029 
   3030 	    /*
   3031 	     * If we have not parsed up to st.endc or ':',
   3032 	     * we are not interested.
   3033 	     */
   3034 	    if (rval[0] != '\0' &&
   3035 		(c = *nested_p) != '\0' && c != ':' && c != st.endc) {
   3036 		free(freeIt);
   3037 		/* XXX: apply_mods doesn't sound like "not interested". */
   3038 		goto apply_mods;
   3039 	    }
   3040 
   3041 	    VAR_DEBUG("Indirect modifier \"%s\" from \"%.*s\"\n",
   3042 		      rval, (int)(size_t)(nested_p - p), p);
   3043 
   3044 	    p = nested_p;
   3045 
   3046 	    if (rval[0] != '\0') {
   3047 		const char *rval_pp = rval;
   3048 		st.val = ApplyModifiers(&rval_pp, st.val, '\0', '\0', v,
   3049 					exprFlags, ctxt, eflags, freePtr);
   3050 		if (st.val == var_Error
   3051 		    || (st.val == varNoError && !(st.eflags & VARE_UNDEFERR))
   3052 		    || *rval_pp != '\0') {
   3053 		    free(freeIt);
   3054 		    goto out;	/* error already reported */
   3055 		}
   3056 	    }
   3057 	    free(freeIt);
   3058 	    if (*p == ':')
   3059 		p++;
   3060 	    else if (*p == '\0' && endc != '\0') {
   3061 		Error("Unclosed variable specification after complex "
   3062 		      "modifier (expecting '%c') for %s", st.endc, st.v->name);
   3063 		goto out;
   3064 	    }
   3065 	    continue;
   3066 	}
   3067     apply_mods:
   3068 	st.newVal = var_Error;	/* default value, in case of errors */
   3069 	res = AMR_BAD;		/* just a safe fallback */
   3070 	mod = p;
   3071 
   3072 	if (DEBUG(VAR)) {
   3073 	    char eflags_str[VarEvalFlags_ToStringSize];
   3074 	    char vflags_str[VarFlags_ToStringSize];
   3075 	    char exprflags_str[VarExprFlags_ToStringSize];
   3076 	    Boolean is_single_char = mod[0] != '\0' &&
   3077 				     (mod[1] == endc || mod[1] == ':');
   3078 
   3079 	    /* At this point, only the first character of the modifier can
   3080 	     * be used since the end of the modifier is not yet known. */
   3081 	    VAR_DEBUG("Applying ${%s:%c%s} to \"%s\" (%s, %s, %s)\n",
   3082 		      st.v->name, mod[0], is_single_char ? "" : "...", st.val,
   3083 		      Enum_FlagsToString(eflags_str, sizeof eflags_str,
   3084 					 st.eflags, VarEvalFlags_ToStringSpecs),
   3085 		      Enum_FlagsToString(vflags_str, sizeof vflags_str,
   3086 					 st.v->flags, VarFlags_ToStringSpecs),
   3087 		      Enum_FlagsToString(exprflags_str, sizeof exprflags_str,
   3088 					 st.exprFlags,
   3089 					 VarExprFlags_ToStringSpecs));
   3090 	}
   3091 
   3092 	switch (*mod) {
   3093 	case ':':
   3094 	    res = ApplyModifier_Assign(&p, &st);
   3095 	    break;
   3096 	case '@':
   3097 	    res = ApplyModifier_Loop(&p, &st);
   3098 	    break;
   3099 	case '_':
   3100 	    res = ApplyModifier_Remember(&p, &st);
   3101 	    break;
   3102 	case 'D':
   3103 	case 'U':
   3104 	    res = ApplyModifier_Defined(&p, &st);
   3105 	    break;
   3106 	case 'L':
   3107 	    ApplyModifiersState_Define(&st);
   3108 	    st.newVal = bmake_strdup(st.v->name);
   3109 	    p++;
   3110 	    res = AMR_OK;
   3111 	    break;
   3112 	case 'P':
   3113 	    res = ApplyModifier_Path(&p, &st);
   3114 	    break;
   3115 	case '!':
   3116 	    res = ApplyModifier_ShellCommand(&p, &st);
   3117 	    break;
   3118 	case '[':
   3119 	    res = ApplyModifier_Words(&p, &st);
   3120 	    break;
   3121 	case 'g':
   3122 	    res = ApplyModifier_Gmtime(&p, &st);
   3123 	    break;
   3124 	case 'h':
   3125 	    res = ApplyModifier_Hash(&p, &st);
   3126 	    break;
   3127 	case 'l':
   3128 	    res = ApplyModifier_Localtime(&p, &st);
   3129 	    break;
   3130 	case 't':
   3131 	    res = ApplyModifier_To(&p, &st);
   3132 	    break;
   3133 	case 'N':
   3134 	case 'M':
   3135 	    res = ApplyModifier_Match(&p, &st);
   3136 	    break;
   3137 	case 'S':
   3138 	    res = ApplyModifier_Subst(&p, &st);
   3139 	    break;
   3140 	case '?':
   3141 	    res = ApplyModifier_IfElse(&p, &st);
   3142 	    break;
   3143 #ifndef NO_REGEX
   3144 	case 'C':
   3145 	    res = ApplyModifier_Regex(&p, &st);
   3146 	    break;
   3147 #endif
   3148 	case 'q':
   3149 	case 'Q':
   3150 	    if (p[1] == st.endc || p[1] == ':') {
   3151 		st.newVal = VarQuote(st.val, *mod == 'q');
   3152 		p++;
   3153 		res = AMR_OK;
   3154 	    } else
   3155 		res = AMR_UNKNOWN;
   3156 	    break;
   3157 	case 'T':
   3158 	    res = ApplyModifier_WordFunc(&p, &st, ModifyWord_Tail);
   3159 	    break;
   3160 	case 'H':
   3161 	    res = ApplyModifier_WordFunc(&p, &st, ModifyWord_Head);
   3162 	    break;
   3163 	case 'E':
   3164 	    res = ApplyModifier_WordFunc(&p, &st, ModifyWord_Suffix);
   3165 	    break;
   3166 	case 'R':
   3167 	    res = ApplyModifier_WordFunc(&p, &st, ModifyWord_Root);
   3168 	    break;
   3169 	case 'r':
   3170 	    res = ApplyModifier_Range(&p, &st);
   3171 	    break;
   3172 	case 'O':
   3173 	    res = ApplyModifier_Order(&p, &st);
   3174 	    break;
   3175 	case 'u':
   3176 	    if (p[1] == st.endc || p[1] == ':') {
   3177 		st.newVal = VarUniq(st.val);
   3178 		p++;
   3179 		res = AMR_OK;
   3180 	    } else
   3181 		res = AMR_UNKNOWN;
   3182 	    break;
   3183 #ifdef SUNSHCMD
   3184 	case 's':
   3185 	    if (p[1] == 'h' && (p[2] == st.endc || p[2] == ':')) {
   3186 		if (st.eflags & VARE_WANTRES) {
   3187 		    const char *errfmt;
   3188 		    st.newVal = Cmd_Exec(st.val, &errfmt);
   3189 		    if (errfmt)
   3190 			Error(errfmt, st.val);
   3191 		} else
   3192 		    st.newVal = varNoError;
   3193 		p += 2;
   3194 		res = AMR_OK;
   3195 	    } else
   3196 		res = AMR_UNKNOWN;
   3197 	    break;
   3198 #endif
   3199 	default:
   3200 	    res = AMR_UNKNOWN;
   3201 	}
   3202 
   3203 #ifdef SYSVVARSUB
   3204 	if (res == AMR_UNKNOWN) {
   3205 	    assert(p == mod);
   3206 	    res = ApplyModifier_SysV(&p, &st);
   3207 	}
   3208 #endif
   3209 
   3210 	if (res == AMR_UNKNOWN) {
   3211 	    Error("Unknown modifier '%c'", *mod);
   3212 	    for (p++; *p != ':' && *p != st.endc && *p != '\0'; p++)
   3213 		continue;
   3214 	    st.newVal = var_Error;
   3215 	}
   3216 	if (res == AMR_CLEANUP)
   3217 	    goto cleanup;
   3218 	if (res == AMR_BAD)
   3219 	    goto bad_modifier;
   3220 
   3221 	if (DEBUG(VAR)) {
   3222 	    char eflags_str[VarEvalFlags_ToStringSize];
   3223 	    char vflags_str[VarFlags_ToStringSize];
   3224 	    char exprflags_str[VarExprFlags_ToStringSize];
   3225 	    const char *quot = st.newVal == var_Error ? "" : "\"";
   3226 	    const char *newVal = st.newVal == var_Error ? "error" : st.newVal;
   3227 
   3228 	    VAR_DEBUG("Result of ${%s:%.*s} is %s%s%s (%s, %s, %s)\n",
   3229 		      st.v->name, (int)(p - mod), mod, quot, newVal, quot,
   3230 		      Enum_FlagsToString(eflags_str, sizeof eflags_str,
   3231 					 st.eflags, VarEvalFlags_ToStringSpecs),
   3232 		      Enum_FlagsToString(vflags_str, sizeof vflags_str,
   3233 					 st.v->flags, VarFlags_ToStringSpecs),
   3234 		      Enum_FlagsToString(exprflags_str, sizeof exprflags_str,
   3235 					 st.exprFlags,
   3236 					 VarExprFlags_ToStringSpecs));
   3237 	}
   3238 
   3239 	if (st.newVal != st.val) {
   3240 	    if (*freePtr) {
   3241 		free(st.val);
   3242 		*freePtr = NULL;
   3243 	    }
   3244 	    st.val = st.newVal;
   3245 	    if (st.val != var_Error && st.val != varNoError) {
   3246 		*freePtr = st.val;
   3247 	    }
   3248 	}
   3249 	if (*p == '\0' && st.endc != '\0') {
   3250 	    Error("Unclosed variable specification (expecting '%c') "
   3251 		  "for \"%s\" (value \"%s\") modifier %c",
   3252 		  st.endc, st.v->name, st.val, *mod);
   3253 	} else if (*p == ':') {
   3254 	    p++;
   3255 	}
   3256 	mod = p;
   3257     }
   3258 out:
   3259     *pp = p;
   3260     assert(st.val != NULL);	/* Use var_Error or varNoError instead. */
   3261     *exprFlags = st.exprFlags;
   3262     return st.val;
   3263 
   3264 bad_modifier:
   3265     Error("Bad modifier `:%.*s' for %s",
   3266 	  (int)strcspn(mod, ":)}"), mod, st.v->name);
   3267 
   3268 cleanup:
   3269     *pp = p;
   3270     if (st.missing_delim != '\0')
   3271 	Error("Unfinished modifier for %s ('%c' missing)",
   3272 	      st.v->name, st.missing_delim);
   3273     free(*freePtr);
   3274     *freePtr = NULL;
   3275     *exprFlags = st.exprFlags;
   3276     return var_Error;
   3277 }
   3278 
   3279 static Boolean
   3280 VarIsDynamic(GNode *ctxt, const char *varname, size_t namelen)
   3281 {
   3282     if ((namelen == 1 ||
   3283 	 (namelen == 2 && (varname[1] == 'F' || varname[1] == 'D'))) &&
   3284 	(ctxt == VAR_CMD || ctxt == VAR_GLOBAL))
   3285     {
   3286 	/*
   3287 	 * If substituting a local variable in a non-local context,
   3288 	 * assume it's for dynamic source stuff. We have to handle
   3289 	 * this specially and return the longhand for the variable
   3290 	 * with the dollar sign escaped so it makes it back to the
   3291 	 * caller. Only four of the local variables are treated
   3292 	 * specially as they are the only four that will be set
   3293 	 * when dynamic sources are expanded.
   3294 	 */
   3295 	switch (varname[0]) {
   3296 	case '@':
   3297 	case '%':
   3298 	case '*':
   3299 	case '!':
   3300 	    return TRUE;
   3301 	}
   3302 	return FALSE;
   3303     }
   3304 
   3305     if ((namelen == 7 || namelen == 8) && varname[0] == '.' &&
   3306 	ch_isupper(varname[1]) && (ctxt == VAR_CMD || ctxt == VAR_GLOBAL))
   3307     {
   3308 	return strcmp(varname, ".TARGET") == 0 ||
   3309 	       strcmp(varname, ".ARCHIVE") == 0 ||
   3310 	       strcmp(varname, ".PREFIX") == 0 ||
   3311 	       strcmp(varname, ".MEMBER") == 0;
   3312     }
   3313 
   3314     return FALSE;
   3315 }
   3316 
   3317 static const char *
   3318 ShortVarValue(char varname, const GNode *ctxt, VarEvalFlags eflags)
   3319 {
   3320     if (ctxt == VAR_CMD || ctxt == VAR_GLOBAL) {
   3321 	/*
   3322 	 * If substituting a local variable in a non-local context,
   3323 	 * assume it's for dynamic source stuff. We have to handle
   3324 	 * this specially and return the longhand for the variable
   3325 	 * with the dollar sign escaped so it makes it back to the
   3326 	 * caller. Only four of the local variables are treated
   3327 	 * specially as they are the only four that will be set
   3328 	 * when dynamic sources are expanded.
   3329 	 */
   3330 	switch (varname) {
   3331 	case '@':
   3332 	    return "$(.TARGET)";
   3333 	case '%':
   3334 	    return "$(.MEMBER)";
   3335 	case '*':
   3336 	    return "$(.PREFIX)";
   3337 	case '!':
   3338 	    return "$(.ARCHIVE)";
   3339 	}
   3340     }
   3341     return eflags & VARE_UNDEFERR ? var_Error : varNoError;
   3342 }
   3343 
   3344 /* Parse a variable name, until the end character or a colon, whichever
   3345  * comes first. */
   3346 static char *
   3347 ParseVarname(const char **pp, char startc, char endc,
   3348 	     GNode *ctxt, VarEvalFlags eflags,
   3349 	     size_t *out_varname_len)
   3350 {
   3351     Buffer buf;
   3352     const char *p = *pp;
   3353     int depth = 1;
   3354 
   3355     Buf_Init(&buf, 0);
   3356 
   3357     while (*p != '\0') {
   3358 	/* Track depth so we can spot parse errors. */
   3359 	if (*p == startc)
   3360 	    depth++;
   3361 	if (*p == endc) {
   3362 	    if (--depth == 0)
   3363 		break;
   3364 	}
   3365 	if (*p == ':' && depth == 1)
   3366 	    break;
   3367 
   3368 	/* A variable inside a variable, expand. */
   3369 	if (*p == '$') {
   3370 	    void *freeIt;
   3371 	    const char *rval;
   3372 	    (void)Var_Parse(&p, ctxt, eflags, &rval, &freeIt);
   3373 	    /* TODO: handle errors */
   3374 	    Buf_AddStr(&buf, rval);
   3375 	    free(freeIt);
   3376 	} else {
   3377 	    Buf_AddByte(&buf, *p);
   3378 	    p++;
   3379 	}
   3380     }
   3381     *pp = p;
   3382     *out_varname_len = Buf_Size(&buf);
   3383     return Buf_Destroy(&buf, FALSE);
   3384 }
   3385 
   3386 static Boolean
   3387 ValidShortVarname(char varname, const char *start)
   3388 {
   3389     switch (varname) {
   3390     case '\0':
   3391     case ')':
   3392     case '}':
   3393     case ':':
   3394     case '$':
   3395 	break;			/* and continue below */
   3396     default:
   3397         return TRUE;
   3398     }
   3399 
   3400     if (!DEBUG(LINT))
   3401 	return FALSE;
   3402 
   3403     if (varname == '$')
   3404 	Parse_Error(PARSE_FATAL,
   3405 		    "To escape a dollar, use \\$, not $$, at \"%s\"", start);
   3406     else if (varname == '\0')
   3407 	Parse_Error(PARSE_FATAL, "Dollar followed by nothing");
   3408     else
   3409 	Parse_Error(PARSE_FATAL,
   3410 		    "Invalid variable name '%c', at \"%s\"", varname, start);
   3411 
   3412     return FALSE;
   3413 }
   3414 
   3415 /*-
   3416  *-----------------------------------------------------------------------
   3417  * Var_Parse --
   3418  *	Given the start of a variable expression (such as $v, $(VAR),
   3419  *	${VAR:Mpattern}), extract the variable name, possibly some
   3420  *	modifiers and find its value by applying the modifiers to the
   3421  *	original value.
   3422  *
   3423  * Input:
   3424  *	str		The string to parse
   3425  *	ctxt		The context for the variable
   3426  *	flags		VARE_UNDEFERR	if undefineds are an error
   3427  *			VARE_WANTRES	if we actually want the result
   3428  *			VARE_ASSIGN	if we are in a := assignment
   3429  *	lengthPtr	OUT: The length of the specification
   3430  *	freePtr		OUT: Non-NULL if caller should free *freePtr
   3431  *
   3432  * Results:
   3433  *	Returns the value of the variable expression, never NULL.
   3434  *	var_Error if there was a parse error and VARE_UNDEFERR was set.
   3435  *	varNoError if there was a parse error and VARE_UNDEFERR was not set.
   3436  *
   3437  *	Parsing should continue at str + *lengthPtr.
   3438  *	TODO: Document the value of *lengthPtr on parse errors.  It might be
   3439  *	0, or +1, or the index of the parse error, or the guessed end of the
   3440  *	variable expression.
   3441  *
   3442  *	If var_Error is returned, a diagnostic may or may not have been
   3443  *	printed. XXX: This is inconsistent.
   3444  *
   3445  *	If varNoError is returned, a diagnostic may or may not have been
   3446  *	printed. XXX: This is inconsistent, and as of 2020-09-08, returning
   3447  *	varNoError is even used to return a regular, non-error empty string.
   3448  *
   3449  *	After using the returned value, *freePtr must be freed, preferably
   3450  *	using bmake_free since it is NULL in most cases.
   3451  *
   3452  * Side Effects:
   3453  *	Any effects from the modifiers, such as :!cmd! or ::=value.
   3454  *-----------------------------------------------------------------------
   3455  */
   3456 /* coverity[+alloc : arg-*4] */
   3457 VarParseResult
   3458 Var_Parse(const char **pp, GNode *ctxt, VarEvalFlags eflags,
   3459 	  const char **out_val, void **freePtr)
   3460 {
   3461     const char *const start = *pp;
   3462     const char *p;
   3463     Boolean 	 haveModifier;	/* TRUE if have modifiers for the variable */
   3464     char	 startc;	/* Starting character if variable in parens
   3465 				 * or braces */
   3466     char	 endc;		/* Ending character if variable in parens
   3467 				 * or braces */
   3468     Boolean	 dynamic;	/* TRUE if the variable is local and we're
   3469 				 * expanding it in a non-local context. This
   3470 				 * is done to support dynamic sources. The
   3471 				 * result is just the expression, unaltered */
   3472     const char *extramodifiers;
   3473     Var *v;
   3474     char *nstr;
   3475     char eflags_str[VarEvalFlags_ToStringSize];
   3476     VarExprFlags exprFlags = 0;
   3477 
   3478     VAR_DEBUG("%s: %s with %s\n", __func__, start,
   3479 	      Enum_FlagsToString(eflags_str, sizeof eflags_str, eflags,
   3480 				 VarEvalFlags_ToStringSpecs));
   3481 
   3482     *freePtr = NULL;
   3483     extramodifiers = NULL;	/* extra modifiers to apply first */
   3484     dynamic = FALSE;
   3485 
   3486     /* Appease GCC, which thinks that the variable might not be
   3487      * initialized. */
   3488     endc = '\0';
   3489 
   3490     startc = start[1];
   3491     if (startc != '(' && startc != '{') {
   3492 	char name[2];
   3493 
   3494 	/*
   3495 	 * If it's not bounded by braces of some sort, life is much simpler.
   3496 	 * We just need to check for the first character and return the
   3497 	 * value if it exists.
   3498 	 */
   3499 
   3500 	if (!ValidShortVarname(startc, start)) {
   3501 	    (*pp)++;
   3502 	    *out_val = var_Error;
   3503 	    return VPR_PARSE_MSG;
   3504 	}
   3505 
   3506 	name[0] = startc;
   3507 	name[1] = '\0';
   3508 	v = VarFind(name, ctxt, FIND_ENV | FIND_GLOBAL | FIND_CMD);
   3509 	if (v == NULL) {
   3510 	    *pp += 2;
   3511 
   3512 	    *out_val = ShortVarValue(startc, ctxt, eflags);
   3513 	    if (DEBUG(LINT) && *out_val == var_Error) {
   3514 		Parse_Error(PARSE_FATAL, "Variable \"%s\" is undefined", name);
   3515 		return VPR_UNDEF_MSG;
   3516 	    }
   3517 	    return eflags & VARE_UNDEFERR ? VPR_UNDEF_SILENT : VPR_OK;
   3518 	} else {
   3519 	    haveModifier = FALSE;
   3520 	    p = start + 1;
   3521 	}
   3522     } else {
   3523 	size_t namelen;
   3524 	char *varname;
   3525 
   3526 	endc = startc == '(' ? ')' : '}';
   3527 
   3528 	p = start + 2;
   3529 	varname = ParseVarname(&p, startc, endc, ctxt, eflags, &namelen);
   3530 
   3531 	if (*p == ':') {
   3532 	    haveModifier = TRUE;
   3533 	} else if (*p == endc) {
   3534 	    haveModifier = FALSE;
   3535 	} else {
   3536 	    Parse_Error(PARSE_FATAL, "Unclosed variable \"%s\"", varname);
   3537 	    *pp = p;
   3538 	    free(varname);
   3539 	    *out_val = var_Error;
   3540 	    return VPR_PARSE_MSG;
   3541 	}
   3542 
   3543 	v = VarFind(varname, ctxt, FIND_ENV | FIND_GLOBAL | FIND_CMD);
   3544 
   3545 	/* At this point, p points just after the variable name,
   3546 	 * either at ':' or at endc. */
   3547 
   3548 	/*
   3549 	 * Check also for bogus D and F forms of local variables since we're
   3550 	 * in a local context and the name is the right length.
   3551 	 */
   3552 	if (v == NULL && ctxt != VAR_CMD && ctxt != VAR_GLOBAL &&
   3553 	    namelen == 2 && (varname[1] == 'F' || varname[1] == 'D') &&
   3554 	    strchr("@%?*!<>", varname[0]) != NULL)
   3555 	{
   3556 	    /*
   3557 	     * Well, it's local -- go look for it.
   3558 	     */
   3559 	    char name[] = { varname[0], '\0' };
   3560 	    v = VarFind(name, ctxt, 0);
   3561 
   3562 	    if (v != NULL) {
   3563 		if (varname[1] == 'D') {
   3564 		    extramodifiers = "H:";
   3565 		} else { /* F */
   3566 		    extramodifiers = "T:";
   3567 		}
   3568 	    }
   3569 	}
   3570 
   3571 	if (v == NULL) {
   3572 	    dynamic = VarIsDynamic(ctxt, varname, namelen);
   3573 
   3574 	    if (!haveModifier) {
   3575 	        p++;		/* skip endc */
   3576 		*pp = p;
   3577 		if (dynamic) {
   3578 		    char *pstr = bmake_strsedup(start, p);
   3579 		    *freePtr = pstr;
   3580 		    free(varname);
   3581 		    *out_val = pstr;
   3582 		    return VPR_OK;
   3583 		}
   3584 
   3585 		if ((eflags & VARE_UNDEFERR) && (eflags & VARE_WANTRES) &&
   3586 		    DEBUG(LINT))
   3587 		{
   3588 		    Parse_Error(PARSE_FATAL, "Variable \"%s\" is undefined",
   3589 				varname);
   3590 		    free(varname);
   3591 		    *out_val = var_Error;
   3592 		    return VPR_UNDEF_MSG;
   3593 		}
   3594 
   3595 		if (eflags & VARE_UNDEFERR) {
   3596 		    free(varname);
   3597 		    *out_val = var_Error;
   3598 		    return VPR_UNDEF_SILENT;
   3599 		}
   3600 
   3601 		free(varname);
   3602 		*out_val = varNoError;
   3603 		return VPR_OK;
   3604 	    }
   3605 
   3606 	    /* The variable expression is based on an undefined variable.
   3607 	     * Nevertheless it needs a Var, for modifiers that access the
   3608 	     * variable name, such as :L or :?.
   3609 	     *
   3610 	     * Most modifiers leave this expression in the "undefined" state
   3611 	     * (VEF_UNDEF), only a few modifiers like :D, :U, :L, :P turn this
   3612 	     * undefined expression into a defined expression (VEF_DEF).
   3613 	     *
   3614 	     * At the end, after applying all modifiers, if the expression
   3615 	     * is still undefined, Var_Parse will return an empty string
   3616 	     * instead of the actually computed value. */
   3617 	    v = bmake_malloc(sizeof(Var));
   3618 	    v->name = varname;
   3619 	    Buf_Init(&v->val, 1);
   3620 	    v->flags = 0;
   3621 	    exprFlags = VEF_UNDEF;
   3622 	} else
   3623 	    free(varname);
   3624     }
   3625 
   3626     if (v->flags & VAR_IN_USE) {
   3627 	Fatal("Variable %s is recursive.", v->name);
   3628 	/*NOTREACHED*/
   3629     } else {
   3630 	v->flags |= VAR_IN_USE;
   3631     }
   3632 
   3633     /*
   3634      * Before doing any modification, we have to make sure the value
   3635      * has been fully expanded. If it looks like recursion might be
   3636      * necessary (there's a dollar sign somewhere in the variable's value)
   3637      * we just call Var_Subst to do any other substitutions that are
   3638      * necessary. Note that the value returned by Var_Subst will have
   3639      * been dynamically-allocated, so it will need freeing when we
   3640      * return.
   3641      */
   3642     nstr = Buf_GetAll(&v->val, NULL);
   3643     if (strchr(nstr, '$') != NULL && (eflags & VARE_WANTRES)) {
   3644         VarEvalFlags nested_eflags = eflags;
   3645         if (DEBUG(LINT))
   3646             nested_eflags &= ~(unsigned)VARE_UNDEFERR;
   3647 	nstr = Var_Subst(nstr, ctxt, nested_eflags);
   3648 	*freePtr = nstr;
   3649     }
   3650 
   3651     v->flags &= ~(unsigned)VAR_IN_USE;
   3652 
   3653     if (haveModifier || extramodifiers != NULL) {
   3654 	void *extraFree;
   3655 
   3656 	extraFree = NULL;
   3657 	if (extramodifiers != NULL) {
   3658 	    const char *em = extramodifiers;
   3659 	    nstr = ApplyModifiers(&em, nstr, '(', ')',
   3660 				  v, &exprFlags, ctxt, eflags, &extraFree);
   3661 	}
   3662 
   3663 	if (haveModifier) {
   3664 	    /* Skip initial colon. */
   3665 	    p++;
   3666 
   3667 	    nstr = ApplyModifiers(&p, nstr, startc, endc,
   3668 				  v, &exprFlags, ctxt, eflags, freePtr);
   3669 	    free(extraFree);
   3670 	} else {
   3671 	    *freePtr = extraFree;
   3672 	}
   3673     }
   3674 
   3675     if (*p != '\0')		/* Skip past endc if possible. */
   3676 	p++;
   3677 
   3678     *pp = p;
   3679 
   3680     if (v->flags & VAR_FROM_ENV) {
   3681         /* Free the environment variable now since we own it,
   3682          * but don't free the variable value if it will be returned. */
   3683 	Boolean keepValue = nstr == Buf_GetAll(&v->val, NULL);
   3684 	if (keepValue)
   3685 	    *freePtr = nstr;
   3686 	(void)VarFreeEnv(v, !keepValue);
   3687 
   3688     } else if (exprFlags & VEF_UNDEF) {
   3689 	if (!(exprFlags & VEF_DEF)) {
   3690 	    if (*freePtr != NULL) {
   3691 		free(*freePtr);
   3692 		*freePtr = NULL;
   3693 	    }
   3694 	    if (dynamic) {
   3695 		nstr = bmake_strsedup(start, p);
   3696 		*freePtr = nstr;
   3697 	    } else {
   3698 		/* The expression is still undefined, therefore discard the
   3699 		 * actual value and return an empty string instead. */
   3700 		nstr = (eflags & VARE_UNDEFERR) ? var_Error : varNoError;
   3701 	    }
   3702 	}
   3703 	if (nstr != Buf_GetAll(&v->val, NULL))
   3704 	    Buf_Destroy(&v->val, TRUE);
   3705 	free(v->name);
   3706 	free(v);
   3707     }
   3708     *out_val = nstr;
   3709     return VPR_UNKNOWN;
   3710 }
   3711 
   3712 /* Substitute for all variables in the given string in the given context.
   3713  *
   3714  * If eflags & VARE_UNDEFERR, Parse_Error will be called when an undefined
   3715  * variable is encountered.
   3716  *
   3717  * If eflags & VARE_WANTRES, any effects from the modifiers, such as ::=,
   3718  * :sh or !cmd! take place.
   3719  *
   3720  * Input:
   3721  *	str		the string which to substitute
   3722  *	ctxt		the context wherein to find variables
   3723  *	eflags		VARE_UNDEFERR	if undefineds are an error
   3724  *			VARE_WANTRES	if we actually want the result
   3725  *			VARE_ASSIGN	if we are in a := assignment
   3726  *
   3727  * Results:
   3728  *	The resulting string.
   3729  */
   3730 char *
   3731 Var_Subst(const char *str, GNode *ctxt, VarEvalFlags eflags)
   3732 {
   3733     Buffer buf;			/* Buffer for forming things */
   3734     Boolean trailingBackslash;
   3735 
   3736     /* Set true if an error has already been reported,
   3737      * to prevent a plethora of messages when recursing */
   3738     static Boolean errorReported;
   3739 
   3740     Buf_Init(&buf, 0);
   3741     errorReported = FALSE;
   3742     trailingBackslash = FALSE;	/* variable ends in \ */
   3743 
   3744     while (*str) {
   3745 	if (*str == '\n' && trailingBackslash)
   3746 	    Buf_AddByte(&buf, ' ');
   3747 
   3748 	if (*str == '$' && str[1] == '$') {
   3749 	    /*
   3750 	     * A dollar sign may be escaped with another dollar sign.
   3751 	     * In such a case, we skip over the escape character and store the
   3752 	     * dollar sign into the buffer directly.
   3753 	     */
   3754 	    if (save_dollars && (eflags & VARE_ASSIGN))
   3755 		Buf_AddByte(&buf, '$');
   3756 	    Buf_AddByte(&buf, '$');
   3757 	    str += 2;
   3758 	} else if (*str != '$') {
   3759 	    /*
   3760 	     * Skip as many characters as possible -- either to the end of
   3761 	     * the string or to the next dollar sign (variable expression).
   3762 	     */
   3763 	    const char *cp;
   3764 
   3765 	    for (cp = str++; *str != '$' && *str != '\0'; str++)
   3766 		continue;
   3767 	    Buf_AddBytesBetween(&buf, cp, str);
   3768 	} else {
   3769 	    const char *nested_str = str;
   3770 	    void *freeIt;
   3771 	    const char *val;
   3772 	    (void)Var_Parse(&nested_str, ctxt, eflags, &val, &freeIt);
   3773 	    /* TODO: handle errors */
   3774 
   3775 	    if (val == var_Error || val == varNoError) {
   3776 		/*
   3777 		 * If performing old-time variable substitution, skip over
   3778 		 * the variable and continue with the substitution. Otherwise,
   3779 		 * store the dollar sign and advance str so we continue with
   3780 		 * the string...
   3781 		 */
   3782 		if (oldVars) {
   3783 		    str = nested_str;
   3784 		} else if ((eflags & VARE_UNDEFERR) || val == var_Error) {
   3785 		    /*
   3786 		     * If variable is undefined, complain and skip the
   3787 		     * variable. The complaint will stop us from doing anything
   3788 		     * when the file is parsed.
   3789 		     */
   3790 		    if (!errorReported) {
   3791 			Parse_Error(PARSE_FATAL, "Undefined variable \"%.*s\"",
   3792 				    (int)(size_t)(nested_str - str), str);
   3793 		    }
   3794 		    str = nested_str;
   3795 		    errorReported = TRUE;
   3796 		} else {
   3797 		    Buf_AddByte(&buf, *str);
   3798 		    str++;
   3799 		}
   3800 	    } else {
   3801 		size_t val_len;
   3802 
   3803 		str = nested_str;
   3804 
   3805 		val_len = strlen(val);
   3806 		Buf_AddBytes(&buf, val, val_len);
   3807 		trailingBackslash = val_len > 0 && val[val_len - 1] == '\\';
   3808 	    }
   3809 	    free(freeIt);
   3810 	    freeIt = NULL;
   3811 	}
   3812     }
   3813 
   3814     return Buf_DestroyCompact(&buf);
   3815 }
   3816 
   3817 /* Initialize the module. */
   3818 void
   3819 Var_Init(void)
   3820 {
   3821     VAR_INTERNAL = Targ_NewGN("Internal");
   3822     VAR_GLOBAL = Targ_NewGN("Global");
   3823     VAR_CMD = Targ_NewGN("Command");
   3824 }
   3825 
   3826 
   3827 void
   3828 Var_End(void)
   3829 {
   3830     Var_Stats();
   3831 }
   3832 
   3833 void
   3834 Var_Stats(void)
   3835 {
   3836     Hash_DebugStats(&VAR_GLOBAL->context, "VAR_GLOBAL");
   3837 }
   3838 
   3839 
   3840 /****************** PRINT DEBUGGING INFO *****************/
   3841 static void
   3842 VarPrintVar(void *vp, void *data MAKE_ATTR_UNUSED)
   3843 {
   3844     Var *v = (Var *)vp;
   3845     fprintf(debug_file, "%-16s = %s\n", v->name, Buf_GetAll(&v->val, NULL));
   3846 }
   3847 
   3848 /* Print all variables in a context, unordered. */
   3849 void
   3850 Var_Dump(GNode *ctxt)
   3851 {
   3852     Hash_ForEach(&ctxt->context, VarPrintVar, NULL);
   3853 }
   3854