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setmode.c revision 1.11 
      1 /*	$NetBSD: setmode.c,v 1.11 1995/03/04 01:55:58 cgd Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 1993, 1994
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Dave Borman at Cray Research, Inc.
      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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #if defined(LIBC_SCCS) && !defined(lint)
     40 #if 0
     41 static char sccsid[] = "@(#)setmode.c	8.2 (Berkeley) 3/25/94";
     42 #else
     43 static char rcsid[] = "$NetBSD: setmode.c,v 1.11 1995/03/04 01:55:58 cgd Exp $";
     44 #endif
     45 #endif /* LIBC_SCCS and not lint */
     46 
     47 #include <sys/types.h>
     48 #include <sys/stat.h>
     49 
     50 #include <ctype.h>
     51 #include <errno.h>
     52 #include <signal.h>
     53 #include <stddef.h>
     54 #include <stdlib.h>
     55 
     56 #ifdef SETMODE_DEBUG
     57 #include <stdio.h>
     58 #endif
     59 
     60 #define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
     61 #define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
     62 
     63 typedef struct bitcmd {
     64 	char	cmd;
     65 	char	cmd2;
     66 	mode_t	bits;
     67 } BITCMD;
     68 
     69 #define	CMD2_CLR	0x01
     70 #define	CMD2_SET	0x02
     71 #define	CMD2_GBITS	0x04
     72 #define	CMD2_OBITS	0x08
     73 #define	CMD2_UBITS	0x10
     74 
     75 static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
     76 static int	 compress_mode __P((BITCMD *));
     77 #ifdef SETMODE_DEBUG
     78 static void	 dumpmode __P((BITCMD *));
     79 #endif
     80 
     81 /*
     82  * Given the old mode and an array of bitcmd structures, apply the operations
     83  * described in the bitcmd structures to the old mode, and return the new mode.
     84  * Note that there is no '=' command; a strict assignment is just a '-' (clear
     85  * bits) followed by a '+' (set bits).
     86  */
     87 mode_t
     88 getmode(bbox, omode)
     89 	void *bbox;
     90 	mode_t omode;
     91 {
     92 	register BITCMD *set;
     93 	register mode_t clrval, newmode, value;
     94 
     95 	set = (BITCMD *)bbox;
     96 	newmode = omode;
     97 	for (value = 0;; set++)
     98 		switch(set->cmd) {
     99 		/*
    100 		 * When copying the user, group or other bits around, we "know"
    101 		 * where the bits are in the mode so that we can do shifts to
    102 		 * copy them around.  If we don't use shifts, it gets real
    103 		 * grundgy with lots of single bit checks and bit sets.
    104 		 */
    105 		case 'u':
    106 			value = (newmode & S_IRWXU) >> 6;
    107 			goto common;
    108 
    109 		case 'g':
    110 			value = (newmode & S_IRWXG) >> 3;
    111 			goto common;
    112 
    113 		case 'o':
    114 			value = newmode & S_IRWXO;
    115 common:			if (set->cmd2 & CMD2_CLR) {
    116 				clrval =
    117 				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
    118 				if (set->cmd2 & CMD2_UBITS)
    119 					newmode &= ~((clrval<<6) & set->bits);
    120 				if (set->cmd2 & CMD2_GBITS)
    121 					newmode &= ~((clrval<<3) & set->bits);
    122 				if (set->cmd2 & CMD2_OBITS)
    123 					newmode &= ~(clrval & set->bits);
    124 			}
    125 			if (set->cmd2 & CMD2_SET) {
    126 				if (set->cmd2 & CMD2_UBITS)
    127 					newmode |= (value<<6) & set->bits;
    128 				if (set->cmd2 & CMD2_GBITS)
    129 					newmode |= (value<<3) & set->bits;
    130 				if (set->cmd2 & CMD2_OBITS)
    131 					newmode |= value & set->bits;
    132 			}
    133 			break;
    134 
    135 		case '+':
    136 			newmode |= set->bits;
    137 			break;
    138 
    139 		case '-':
    140 			newmode &= ~set->bits;
    141 			break;
    142 
    143 		case 'X':
    144 			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
    145 				newmode |= set->bits;
    146 			break;
    147 
    148 		case '\0':
    149 		default:
    150 #ifdef SETMODE_DEBUG
    151 			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
    152 #endif
    153 			return (newmode);
    154 		}
    155 }
    156 
    157 #define	ADDCMD(a, b, c, d)						\
    158 	if (set >= endset) {						\
    159 		register BITCMD *newset;				\
    160 		setlen += SET_LEN_INCR;					\
    161 		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
    162 		if (!saveset)						\
    163 			return (NULL);					\
    164 		set = newset + (set - saveset);				\
    165 		saveset = newset;					\
    166 		endset = newset + (setlen - 2);				\
    167 	}								\
    168 	set = addcmd(set, (a), (b), (c), (d))
    169 
    170 #define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
    171 
    172 void *
    173 setmode(p)
    174 	register char *p;
    175 {
    176 	register int perm, who;
    177 	register char op;
    178 	BITCMD *set, *saveset, *endset;
    179 	sigset_t sigset, sigoset;
    180 	mode_t mask;
    181 	int equalopdone, permXbits, setlen;
    182 
    183 	if (!*p)
    184 		return (NULL);
    185 
    186 	/*
    187 	 * Get a copy of the mask for the permissions that are mask relative.
    188 	 * Flip the bits, we want what's not set.  Since it's possible that
    189 	 * the caller is opening files inside a signal handler, protect them
    190 	 * as best we can.
    191 	 */
    192 	sigfillset(&sigset);
    193         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
    194 	(void)umask(mask = umask(0));
    195 	mask = ~mask;
    196         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
    197 
    198 	setlen = SET_LEN + 2;
    199 
    200 	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
    201 		return (NULL);
    202 	saveset = set;
    203 	endset = set + (setlen - 2);
    204 
    205 	/*
    206 	 * If an absolute number, get it and return; disallow non-octal digits
    207 	 * or illegal bits.
    208 	 */
    209 	if (isdigit(*p)) {
    210 		perm = (mode_t)strtol(p, NULL, 8);
    211 		if (perm & ~(STANDARD_BITS|S_ISTXT)) {
    212 			free(saveset);
    213 			return (NULL);
    214 		}
    215 		while (*++p)
    216 			if (*p < '0' || *p > '7') {
    217 				free(saveset);
    218 				return (NULL);
    219 			}
    220 		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
    221 		return (saveset);
    222 	}
    223 
    224 	/*
    225 	 * Build list of structures to set/clear/copy bits as described by
    226 	 * each clause of the symbolic mode.
    227 	 */
    228 	for (;;) {
    229 		/* First, find out which bits might be modified. */
    230 		for (who = 0;; ++p) {
    231 			switch (*p) {
    232 			case 'a':
    233 				who |= STANDARD_BITS;
    234 				break;
    235 			case 'u':
    236 				who |= S_ISUID|S_IRWXU;
    237 				break;
    238 			case 'g':
    239 				who |= S_ISGID|S_IRWXG;
    240 				break;
    241 			case 'o':
    242 				who |= S_IRWXO;
    243 				break;
    244 			default:
    245 				goto getop;
    246 			}
    247 		}
    248 
    249 getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
    250 			free(saveset);
    251 			return (NULL);
    252 		}
    253 		if (op == '=')
    254 			equalopdone = 0;
    255 
    256 		who &= ~S_ISTXT;
    257 		for (perm = 0, permXbits = 0;; ++p) {
    258 			switch (*p) {
    259 			case 'r':
    260 				perm |= S_IRUSR|S_IRGRP|S_IROTH;
    261 				break;
    262 			case 's':
    263 				/* If only "other" bits ignore set-id. */
    264 				if (who & ~S_IRWXO)
    265 					perm |= S_ISUID|S_ISGID;
    266 				break;
    267 			case 't':
    268 				/* If only "other" bits ignore sticky. */
    269 				if (who & ~S_IRWXO) {
    270 					who |= S_ISTXT;
    271 					perm |= S_ISTXT;
    272 				}
    273 				break;
    274 			case 'w':
    275 				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
    276 				break;
    277 			case 'X':
    278 				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
    279 				break;
    280 			case 'x':
    281 				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
    282 				break;
    283 			case 'u':
    284 			case 'g':
    285 			case 'o':
    286 				/*
    287 				 * When ever we hit 'u', 'g', or 'o', we have
    288 				 * to flush out any partial mode that we have,
    289 				 * and then do the copying of the mode bits.
    290 				 */
    291 				if (perm) {
    292 					ADDCMD(op, who, perm, mask);
    293 					perm = 0;
    294 				}
    295 				if (op == '=')
    296 					equalopdone = 1;
    297 				if (op == '+' && permXbits) {
    298 					ADDCMD('X', who, permXbits, mask);
    299 					permXbits = 0;
    300 				}
    301 				ADDCMD(*p, who, op, mask);
    302 				break;
    303 
    304 			default:
    305 				/*
    306 				 * Add any permissions that we haven't already
    307 				 * done.
    308 				 */
    309 				if (perm || (op == '=' && !equalopdone)) {
    310 					if (op == '=')
    311 						equalopdone = 1;
    312 					ADDCMD(op, who, perm, mask);
    313 					perm = 0;
    314 				}
    315 				if (permXbits) {
    316 					ADDCMD('X', who, permXbits, mask);
    317 					permXbits = 0;
    318 				}
    319 				goto apply;
    320 			}
    321 		}
    322 
    323 apply:		if (!*p)
    324 			break;
    325 		if (*p != ',')
    326 			goto getop;
    327 		++p;
    328 	}
    329 	set->cmd = 0;
    330 #ifdef SETMODE_DEBUG
    331 	(void)printf("Before compress_mode()\n");
    332 	dumpmode(saveset);
    333 #endif
    334 	compress_mode(saveset);
    335 #ifdef SETMODE_DEBUG
    336 	(void)printf("After compress_mode()\n");
    337 	dumpmode(saveset);
    338 #endif
    339 	return (saveset);
    340 }
    341 
    342 static BITCMD *
    343 addcmd(set, op, who, oparg, mask)
    344 	BITCMD *set;
    345 	register int oparg, who;
    346 	register int op;
    347 	u_int mask;
    348 {
    349 	switch (op) {
    350 	case '=':
    351 		set->cmd = '-';
    352 		set->bits = who ? who : STANDARD_BITS;
    353 		set++;
    354 
    355 		op = '+';
    356 		/* FALLTHROUGH */
    357 	case '+':
    358 	case '-':
    359 	case 'X':
    360 		set->cmd = op;
    361 		set->bits = (who ? who : mask) & oparg;
    362 		break;
    363 
    364 	case 'u':
    365 	case 'g':
    366 	case 'o':
    367 		set->cmd = op;
    368 		if (who) {
    369 			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
    370 				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
    371 				    ((who & S_IROTH) ? CMD2_OBITS : 0);
    372 			set->bits = ~0;
    373 		} else {
    374 			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
    375 			set->bits = mask;
    376 		}
    377 
    378 		if (oparg == '+')
    379 			set->cmd2 |= CMD2_SET;
    380 		else if (oparg == '-')
    381 			set->cmd2 |= CMD2_CLR;
    382 		else if (oparg == '=')
    383 			set->cmd2 |= CMD2_SET|CMD2_CLR;
    384 		break;
    385 	}
    386 	return (set + 1);
    387 }
    388 
    389 #ifdef SETMODE_DEBUG
    390 static void
    391 dumpmode(set)
    392 	register BITCMD *set;
    393 {
    394 	for (; set->cmd; ++set)
    395 		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
    396 		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
    397 		    set->cmd2 & CMD2_CLR ? " CLR" : "",
    398 		    set->cmd2 & CMD2_SET ? " SET" : "",
    399 		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
    400 		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
    401 		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
    402 }
    403 #endif
    404 
    405 /*
    406  * Given an array of bitcmd structures, compress by compacting consecutive
    407  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
    408  * 'g' and 'o' commands continue to be separate.  They could probably be
    409  * compacted, but it's not worth the effort.
    410  */
    411 static int
    412 compress_mode(set)
    413 	register BITCMD *set;
    414 {
    415 	register BITCMD *nset;
    416 	register int setbits, clrbits, Xbits, op;
    417 
    418 	for (nset = set;;) {
    419 		/* Copy over any 'u', 'g' and 'o' commands. */
    420 		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
    421 			*set++ = *nset++;
    422 			if (!op)
    423 				return;
    424 		}
    425 
    426 		for (setbits = clrbits = Xbits = 0;; nset++) {
    427 			if ((op = nset->cmd) == '-') {
    428 				clrbits |= nset->bits;
    429 				setbits &= ~nset->bits;
    430 				Xbits &= ~nset->bits;
    431 			} else if (op == '+') {
    432 				setbits |= nset->bits;
    433 				clrbits &= ~nset->bits;
    434 				Xbits &= ~nset->bits;
    435 			} else if (op == 'X')
    436 				Xbits |= nset->bits & ~setbits;
    437 			else
    438 				break;
    439 		}
    440 		if (clrbits) {
    441 			set->cmd = '-';
    442 			set->cmd2 = 0;
    443 			set->bits = clrbits;
    444 			set++;
    445 		}
    446 		if (setbits) {
    447 			set->cmd = '+';
    448 			set->cmd2 = 0;
    449 			set->bits = setbits;
    450 			set++;
    451 		}
    452 		if (Xbits) {
    453 			set->cmd = 'X';
    454 			set->cmd2 = 0;
    455 			set->bits = Xbits;
    456 			set++;
    457 		}
    458 	}
    459 }
    460