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setmode.c revision 1.12 
      1 /*	$NetBSD: setmode.c,v 1.12 1995/03/23 19:51:13 jtc 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 1.12 1995/03/23 19:51:13 jtc 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 <stdlib.h>
     54 
     55 #ifdef SETMODE_DEBUG
     56 #include <stdio.h>
     57 #endif
     58 
     59 #define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
     60 #define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
     61 
     62 typedef struct bitcmd {
     63 	char	cmd;
     64 	char	cmd2;
     65 	mode_t	bits;
     66 } BITCMD;
     67 
     68 #define	CMD2_CLR	0x01
     69 #define	CMD2_SET	0x02
     70 #define	CMD2_GBITS	0x04
     71 #define	CMD2_OBITS	0x08
     72 #define	CMD2_UBITS	0x10
     73 
     74 static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
     75 static int	 compress_mode __P((BITCMD *));
     76 #ifdef SETMODE_DEBUG
     77 static void	 dumpmode __P((BITCMD *));
     78 #endif
     79 
     80 /*
     81  * Given the old mode and an array of bitcmd structures, apply the operations
     82  * described in the bitcmd structures to the old mode, and return the new mode.
     83  * Note that there is no '=' command; a strict assignment is just a '-' (clear
     84  * bits) followed by a '+' (set bits).
     85  */
     86 mode_t
     87 getmode(bbox, omode)
     88 	void *bbox;
     89 	mode_t omode;
     90 {
     91 	register BITCMD *set;
     92 	register mode_t clrval, newmode, value;
     93 
     94 	set = (BITCMD *)bbox;
     95 	newmode = omode;
     96 	for (value = 0;; set++)
     97 		switch(set->cmd) {
     98 		/*
     99 		 * When copying the user, group or other bits around, we "know"
    100 		 * where the bits are in the mode so that we can do shifts to
    101 		 * copy them around.  If we don't use shifts, it gets real
    102 		 * grundgy with lots of single bit checks and bit sets.
    103 		 */
    104 		case 'u':
    105 			value = (newmode & S_IRWXU) >> 6;
    106 			goto common;
    107 
    108 		case 'g':
    109 			value = (newmode & S_IRWXG) >> 3;
    110 			goto common;
    111 
    112 		case 'o':
    113 			value = newmode & S_IRWXO;
    114 common:			if (set->cmd2 & CMD2_CLR) {
    115 				clrval =
    116 				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
    117 				if (set->cmd2 & CMD2_UBITS)
    118 					newmode &= ~((clrval<<6) & set->bits);
    119 				if (set->cmd2 & CMD2_GBITS)
    120 					newmode &= ~((clrval<<3) & set->bits);
    121 				if (set->cmd2 & CMD2_OBITS)
    122 					newmode &= ~(clrval & set->bits);
    123 			}
    124 			if (set->cmd2 & CMD2_SET) {
    125 				if (set->cmd2 & CMD2_UBITS)
    126 					newmode |= (value<<6) & set->bits;
    127 				if (set->cmd2 & CMD2_GBITS)
    128 					newmode |= (value<<3) & set->bits;
    129 				if (set->cmd2 & CMD2_OBITS)
    130 					newmode |= value & set->bits;
    131 			}
    132 			break;
    133 
    134 		case '+':
    135 			newmode |= set->bits;
    136 			break;
    137 
    138 		case '-':
    139 			newmode &= ~set->bits;
    140 			break;
    141 
    142 		case 'X':
    143 			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
    144 				newmode |= set->bits;
    145 			break;
    146 
    147 		case '\0':
    148 		default:
    149 #ifdef SETMODE_DEBUG
    150 			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
    151 #endif
    152 			return (newmode);
    153 		}
    154 }
    155 
    156 #define	ADDCMD(a, b, c, d)						\
    157 	if (set >= endset) {						\
    158 		register BITCMD *newset;				\
    159 		setlen += SET_LEN_INCR;					\
    160 		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
    161 		if (!saveset)						\
    162 			return (NULL);					\
    163 		set = newset + (set - saveset);				\
    164 		saveset = newset;					\
    165 		endset = newset + (setlen - 2);				\
    166 	}								\
    167 	set = addcmd(set, (a), (b), (c), (d))
    168 
    169 #define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
    170 
    171 void *
    172 setmode(p)
    173 	register char *p;
    174 {
    175 	register int perm, who;
    176 	register char op;
    177 	BITCMD *set, *saveset, *endset;
    178 	sigset_t sigset, sigoset;
    179 	mode_t mask;
    180 	int equalopdone, permXbits, setlen;
    181 
    182 	if (!*p)
    183 		return (NULL);
    184 
    185 	/*
    186 	 * Get a copy of the mask for the permissions that are mask relative.
    187 	 * Flip the bits, we want what's not set.  Since it's possible that
    188 	 * the caller is opening files inside a signal handler, protect them
    189 	 * as best we can.
    190 	 */
    191 	sigfillset(&sigset);
    192         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
    193 	(void)umask(mask = umask(0));
    194 	mask = ~mask;
    195         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
    196 
    197 	setlen = SET_LEN + 2;
    198 
    199 	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
    200 		return (NULL);
    201 	saveset = set;
    202 	endset = set + (setlen - 2);
    203 
    204 	/*
    205 	 * If an absolute number, get it and return; disallow non-octal digits
    206 	 * or illegal bits.
    207 	 */
    208 	if (isdigit(*p)) {
    209 		perm = (mode_t)strtol(p, NULL, 8);
    210 		if (perm & ~(STANDARD_BITS|S_ISTXT)) {
    211 			free(saveset);
    212 			return (NULL);
    213 		}
    214 		while (*++p)
    215 			if (*p < '0' || *p > '7') {
    216 				free(saveset);
    217 				return (NULL);
    218 			}
    219 		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
    220 		return (saveset);
    221 	}
    222 
    223 	/*
    224 	 * Build list of structures to set/clear/copy bits as described by
    225 	 * each clause of the symbolic mode.
    226 	 */
    227 	for (;;) {
    228 		/* First, find out which bits might be modified. */
    229 		for (who = 0;; ++p) {
    230 			switch (*p) {
    231 			case 'a':
    232 				who |= STANDARD_BITS;
    233 				break;
    234 			case 'u':
    235 				who |= S_ISUID|S_IRWXU;
    236 				break;
    237 			case 'g':
    238 				who |= S_ISGID|S_IRWXG;
    239 				break;
    240 			case 'o':
    241 				who |= S_IRWXO;
    242 				break;
    243 			default:
    244 				goto getop;
    245 			}
    246 		}
    247 
    248 getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
    249 			free(saveset);
    250 			return (NULL);
    251 		}
    252 		if (op == '=')
    253 			equalopdone = 0;
    254 
    255 		who &= ~S_ISTXT;
    256 		for (perm = 0, permXbits = 0;; ++p) {
    257 			switch (*p) {
    258 			case 'r':
    259 				perm |= S_IRUSR|S_IRGRP|S_IROTH;
    260 				break;
    261 			case 's':
    262 				/* If only "other" bits ignore set-id. */
    263 				if (who & ~S_IRWXO)
    264 					perm |= S_ISUID|S_ISGID;
    265 				break;
    266 			case 't':
    267 				/* If only "other" bits ignore sticky. */
    268 				if (who & ~S_IRWXO) {
    269 					who |= S_ISTXT;
    270 					perm |= S_ISTXT;
    271 				}
    272 				break;
    273 			case 'w':
    274 				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
    275 				break;
    276 			case 'X':
    277 				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
    278 				break;
    279 			case 'x':
    280 				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
    281 				break;
    282 			case 'u':
    283 			case 'g':
    284 			case 'o':
    285 				/*
    286 				 * When ever we hit 'u', 'g', or 'o', we have
    287 				 * to flush out any partial mode that we have,
    288 				 * and then do the copying of the mode bits.
    289 				 */
    290 				if (perm) {
    291 					ADDCMD(op, who, perm, mask);
    292 					perm = 0;
    293 				}
    294 				if (op == '=')
    295 					equalopdone = 1;
    296 				if (op == '+' && permXbits) {
    297 					ADDCMD('X', who, permXbits, mask);
    298 					permXbits = 0;
    299 				}
    300 				ADDCMD(*p, who, op, mask);
    301 				break;
    302 
    303 			default:
    304 				/*
    305 				 * Add any permissions that we haven't already
    306 				 * done.
    307 				 */
    308 				if (perm || (op == '=' && !equalopdone)) {
    309 					if (op == '=')
    310 						equalopdone = 1;
    311 					ADDCMD(op, who, perm, mask);
    312 					perm = 0;
    313 				}
    314 				if (permXbits) {
    315 					ADDCMD('X', who, permXbits, mask);
    316 					permXbits = 0;
    317 				}
    318 				goto apply;
    319 			}
    320 		}
    321 
    322 apply:		if (!*p)
    323 			break;
    324 		if (*p != ',')
    325 			goto getop;
    326 		++p;
    327 	}
    328 	set->cmd = 0;
    329 #ifdef SETMODE_DEBUG
    330 	(void)printf("Before compress_mode()\n");
    331 	dumpmode(saveset);
    332 #endif
    333 	compress_mode(saveset);
    334 #ifdef SETMODE_DEBUG
    335 	(void)printf("After compress_mode()\n");
    336 	dumpmode(saveset);
    337 #endif
    338 	return (saveset);
    339 }
    340 
    341 static BITCMD *
    342 addcmd(set, op, who, oparg, mask)
    343 	BITCMD *set;
    344 	register int oparg, who;
    345 	register int op;
    346 	u_int mask;
    347 {
    348 	switch (op) {
    349 	case '=':
    350 		set->cmd = '-';
    351 		set->bits = who ? who : STANDARD_BITS;
    352 		set++;
    353 
    354 		op = '+';
    355 		/* FALLTHROUGH */
    356 	case '+':
    357 	case '-':
    358 	case 'X':
    359 		set->cmd = op;
    360 		set->bits = (who ? who : mask) & oparg;
    361 		break;
    362 
    363 	case 'u':
    364 	case 'g':
    365 	case 'o':
    366 		set->cmd = op;
    367 		if (who) {
    368 			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
    369 				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
    370 				    ((who & S_IROTH) ? CMD2_OBITS : 0);
    371 			set->bits = ~0;
    372 		} else {
    373 			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
    374 			set->bits = mask;
    375 		}
    376 
    377 		if (oparg == '+')
    378 			set->cmd2 |= CMD2_SET;
    379 		else if (oparg == '-')
    380 			set->cmd2 |= CMD2_CLR;
    381 		else if (oparg == '=')
    382 			set->cmd2 |= CMD2_SET|CMD2_CLR;
    383 		break;
    384 	}
    385 	return (set + 1);
    386 }
    387 
    388 #ifdef SETMODE_DEBUG
    389 static void
    390 dumpmode(set)
    391 	register BITCMD *set;
    392 {
    393 	for (; set->cmd; ++set)
    394 		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
    395 		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
    396 		    set->cmd2 & CMD2_CLR ? " CLR" : "",
    397 		    set->cmd2 & CMD2_SET ? " SET" : "",
    398 		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
    399 		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
    400 		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
    401 }
    402 #endif
    403 
    404 /*
    405  * Given an array of bitcmd structures, compress by compacting consecutive
    406  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
    407  * 'g' and 'o' commands continue to be separate.  They could probably be
    408  * compacted, but it's not worth the effort.
    409  */
    410 static int
    411 compress_mode(set)
    412 	register BITCMD *set;
    413 {
    414 	register BITCMD *nset;
    415 	register int setbits, clrbits, Xbits, op;
    416 
    417 	for (nset = set;;) {
    418 		/* Copy over any 'u', 'g' and 'o' commands. */
    419 		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
    420 			*set++ = *nset++;
    421 			if (!op)
    422 				return;
    423 		}
    424 
    425 		for (setbits = clrbits = Xbits = 0;; nset++) {
    426 			if ((op = nset->cmd) == '-') {
    427 				clrbits |= nset->bits;
    428 				setbits &= ~nset->bits;
    429 				Xbits &= ~nset->bits;
    430 			} else if (op == '+') {
    431 				setbits |= nset->bits;
    432 				clrbits &= ~nset->bits;
    433 				Xbits &= ~nset->bits;
    434 			} else if (op == 'X')
    435 				Xbits |= nset->bits & ~setbits;
    436 			else
    437 				break;
    438 		}
    439 		if (clrbits) {
    440 			set->cmd = '-';
    441 			set->cmd2 = 0;
    442 			set->bits = clrbits;
    443 			set++;
    444 		}
    445 		if (setbits) {
    446 			set->cmd = '+';
    447 			set->cmd2 = 0;
    448 			set->bits = setbits;
    449 			set++;
    450 		}
    451 		if (Xbits) {
    452 			set->cmd = 'X';
    453 			set->cmd2 = 0;
    454 			set->bits = Xbits;
    455 			set++;
    456 		}
    457 	}
    458 }
    459