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setmode.c revision 1.6 
      1 /*
      2  * Copyright (c) 1989 The Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 /*static char *sccsid = "from: @(#)setmode.c	5.6 (Berkeley) 5/27/91";*/
     36 static char *rcsid = "$Id: setmode.c,v 1.6 1994/02/10 23:36:59 cgd Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include <sys/types.h>
     40 #include <sys/stat.h>
     41 #include <signal.h>
     42 #include <errno.h>
     43 #include <stddef.h>
     44 #ifdef SETMODE_DEBUG
     45 #include <stdio.h>
     46 #endif
     47 #include <stdlib.h>
     48 #include <ctype.h>
     49 
     50 #define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
     51 #define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
     52 
     53 typedef struct bitcmd {
     54 	char	cmd;
     55 	char	cmd2;
     56 	mode_t	bits;
     57 } BITCMD;
     58 
     59 #define	CMD2_CLR	0x01
     60 #define	CMD2_SET	0x02
     61 #define	CMD2_GBITS	0x04
     62 #define	CMD2_OBITS	0x08
     63 #define	CMD2_UBITS	0x10
     64 
     65 static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
     66 static int	 compress_mode __P((BITCMD *));
     67 #ifdef SETMODE_DEBUG
     68 static void	 dumpmode __P((BITCMD *));
     69 #endif
     70 
     71 /*
     72  * Given the old mode and an array of bitcmd structures, apply the operations
     73  * described in the bitcmd structures to the old mode, and return the new mode.
     74  * Note that there is no '=' command; a strict assignment is just a '-' (clear
     75  * bits) followed by a '+' (set bits).
     76  */
     77 mode_t
     78 getmode(bbox, omode)
     79 	void *bbox;
     80 	mode_t omode;
     81 {
     82 	register BITCMD *set;
     83 	register mode_t newmode, value;
     84 
     85 	set = (BITCMD *)bbox;
     86 	newmode = omode;
     87 	for (value = 0;; set++)
     88 		switch(set->cmd) {
     89 		/*
     90 		 * When copying the user, group or other bits around, we "know"
     91 		 * where the bits are in the mode so that we can do shifts to
     92 		 * copy them around.  If we don't use shifts, it gets real
     93 		 * grundgy with lots of single bit checks and bit sets.
     94 		 */
     95 		case 'u':
     96 			value = (newmode & S_IRWXU) >> 6;
     97 			goto common;
     98 
     99 		case 'g':
    100 			value = (newmode & S_IRWXG) >> 3;
    101 			goto common;
    102 
    103 		case 'o':
    104 			value = newmode & S_IRWXO;
    105 common:			if (set->cmd2 & CMD2_CLR) {
    106 				if (set->cmd2 & CMD2_UBITS)
    107 					newmode &= ~(S_IRWXU & set->bits);
    108 				if (set->cmd2 & CMD2_GBITS)
    109 					newmode &= ~(S_IRWXG & set->bits);
    110 				if (set->cmd2 & CMD2_OBITS)
    111 					newmode &= ~(S_IRWXO & set->bits);
    112 			}
    113 			if (set->cmd2 & CMD2_SET) {
    114 				if (set->cmd2 & CMD2_UBITS)
    115 					newmode |= (value<<6) & set->bits;
    116 				if (set->cmd2 & CMD2_GBITS)
    117 					newmode |= (value<<3) & set->bits;
    118 				if (set->cmd2 & CMD2_OBITS)
    119 					newmode |= value & set->bits;
    120 			}
    121 			break;
    122 
    123 		case '+':
    124 			newmode |= set->bits;
    125 			break;
    126 
    127 		case '-':
    128 			newmode &= ~set->bits;
    129 			break;
    130 
    131 		case 'X':
    132 			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
    133 				newmode |= set->bits;
    134 			break;
    135 
    136 		case '\0':
    137 		default:
    138 #ifdef SETMODE_DEBUG
    139 			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
    140 #endif
    141 			return (newmode);
    142 		}
    143 }
    144 
    145 #define	ADDCMD(a, b, c, d) \
    146 	if (set >= endset) { \
    147 		register BITCMD *newset; \
    148 		setlen += SET_LEN_INCR; \
    149 		newset = realloc(saveset, sizeof(BITCMD) * setlen); \
    150 		if (!saveset) \
    151 			return (NULL); \
    152 		set = newset + (set - saveset); \
    153 		saveset = newset; \
    154 		endset = newset + (setlen - 2); \
    155 	} \
    156 	set = addcmd(set, (a), (b), (c), (d))
    157 
    158 #define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
    159 
    160 void *
    161 setmode(p)
    162 	register char *p;
    163 {
    164 	register int perm, who;
    165 	register char op;
    166 	BITCMD *set, *saveset, *endset;
    167 	sigset_t sigset, sigoset;
    168 	mode_t mask;
    169 	int permXbits, setlen;
    170 
    171 	if (!*p)
    172 		return (NULL);
    173 
    174 	/*
    175 	 * Get a copy of the mask for the permissions that are mask relative.
    176 	 * Flip the bits, we want what's not set.  Since it's possible that
    177 	 * the caller is opening files inside a signal handler, protect them
    178 	 * as best we can.
    179 	 */
    180 	sigfillset(&sigset);
    181         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
    182 	(void)umask(mask = umask(0));
    183 	mask = ~mask;
    184         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
    185 
    186 	setlen = SET_LEN + 2;
    187 
    188 	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
    189 		return (NULL);
    190 	saveset = set;
    191 	endset = set + (setlen - 2);
    192 
    193 	/*
    194 	 * If an absolute number, get it and return; disallow non-octal digits
    195 	 * or illegal bits.
    196 	 */
    197 	if (isdigit(*p)) {
    198 		perm = (mode_t)strtol(p, (char **)0, 8);
    199 		if (perm & ~(STANDARD_BITS|S_ISTXT)) {
    200 			free(saveset);
    201 			return (NULL);
    202 		}
    203 		while (*++p)
    204 			if (*p < '0' || *p > '7') {
    205 				free(saveset);
    206 				return (NULL);
    207 			}
    208 		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
    209 		return (saveset);
    210 	}
    211 
    212 	/*
    213 	 * Build list of structures to set/clear/copy bits as described by
    214 	 * each clause of the symbolic mode.
    215 	 */
    216 	for (;;) {
    217 		/* First, find out which bits might be modified. */
    218 		for (who = 0;; ++p) {
    219 			switch (*p) {
    220 			case 'a':
    221 				who |= STANDARD_BITS;
    222 				break;
    223 			case 'u':
    224 				who |= S_ISUID|S_IRWXU;
    225 				break;
    226 			case 'g':
    227 				who |= S_ISGID|S_IRWXG;
    228 				break;
    229 			case 'o':
    230 				who |= S_IRWXO;
    231 				break;
    232 			default:
    233 				goto getop;
    234 			}
    235 		}
    236 
    237 getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
    238 			free(saveset);
    239 			return (NULL);
    240 		}
    241 
    242 		who &= ~S_ISTXT;
    243 		for (perm = 0, permXbits = 0;; ++p) {
    244 			switch (*p) {
    245 			case 'r':
    246 				perm |= S_IRUSR|S_IRGRP|S_IROTH;
    247 				break;
    248 			case 's':
    249 				/* If only "other" bits ignore set-id. */
    250 				if (who & ~S_IRWXO)
    251 					perm |= S_ISUID|S_ISGID;
    252 				break;
    253 			case 't':
    254 				/* If only "other" bits ignore sticky. */
    255 				if (who & ~S_IRWXO) {
    256 					who |= S_ISTXT;
    257 					perm |= S_ISTXT;
    258 				}
    259 				break;
    260 			case 'w':
    261 				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
    262 				break;
    263 			case 'X':
    264 				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
    265 				break;
    266 			case 'x':
    267 				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
    268 				break;
    269 			case 'u':
    270 			case 'g':
    271 			case 'o':
    272 				/*
    273 				 * When ever we hit 'u', 'g', or 'o', we have
    274 				 * to flush out any partial mode that we have,
    275 				 * and then do the copying of the mode bits.
    276 				 */
    277 				if (perm || op == '=') {
    278 					ADDCMD(op, who, perm, mask);
    279 					perm = 0;
    280 				}
    281 				if (op == '+' && permXbits) {
    282 					ADDCMD('X', who, permXbits, mask);
    283 					permXbits = 0;
    284 				}
    285 				ADDCMD(*p, who, op, mask);
    286 				break;
    287 
    288 			default:
    289 				/*
    290 				 * Add any permissions that we haven't already
    291 				 * done.
    292 				 */
    293 				if (perm || op == '=') {
    294 					ADDCMD(op, who, perm, mask);
    295 					perm = 0;
    296 				}
    297 				if (permXbits) {
    298 					ADDCMD('X', who, permXbits, mask);
    299 					permXbits = 0;
    300 				}
    301 				goto apply;
    302 			}
    303 		}
    304 
    305 apply:		if (!*p)
    306 			break;
    307 		if (*p != ',')
    308 			goto getop;
    309 		++p;
    310 	}
    311 	set->cmd = 0;
    312 #ifdef SETMODE_DEBUG
    313 	(void)printf("Before compress_mode()\n");
    314 	dumpmode(saveset);
    315 #endif
    316 	compress_mode(saveset);
    317 #ifdef SETMODE_DEBUG
    318 	(void)printf("After compress_mode()\n");
    319 	dumpmode(saveset);
    320 #endif
    321 	return (saveset);
    322 }
    323 
    324 static BITCMD *
    325 addcmd(set, op, who, oparg, mask)
    326 	BITCMD *set;
    327 	register int oparg, who;
    328 	register int op;
    329 	u_int mask;
    330 {
    331 	switch (op) {
    332 	case '+':
    333 	case 'X':
    334 		set->cmd = op;
    335 		set->bits = (who ? who : mask) & oparg;
    336 		break;
    337 
    338 	case '-':
    339 		set->cmd = '-';
    340 		set->bits = (who ? who : (S_IRWXU|S_IRWXG|S_IRWXO)) & oparg;
    341 		break;
    342 
    343 	case '=':
    344 		set->cmd = '-';
    345 		if (!who) {
    346 			set->bits = STANDARD_BITS;
    347 			who = mask;
    348 		} else
    349 			set->bits = who;
    350 		set++;
    351 
    352 		set->cmd = '+';
    353 		set->bits = who & oparg;
    354 		break;
    355 	case 'u':
    356 	case 'g':
    357 	case 'o':
    358 		set->cmd = op;
    359 		if (who) {
    360 			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
    361 				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
    362 				    ((who & S_IROTH) ? CMD2_OBITS : 0);
    363 			set->bits = ~0;
    364 		} else {
    365 			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
    366 			set->bits = mask;
    367 		}
    368 
    369 		if (oparg == '+')
    370 			set->cmd2 |= CMD2_SET;
    371 		else if (oparg == '-')
    372 			set->cmd2 |= CMD2_CLR;
    373 		else if (oparg == '=')
    374 			set->cmd2 |= CMD2_SET|CMD2_CLR;
    375 		break;
    376 	}
    377 	return (set + 1);
    378 }
    379 
    380 #ifdef SETMODE_DEBUG
    381 static void
    382 dumpmode(set)
    383 	register BITCMD *set;
    384 {
    385 	for (; set->cmd; ++set)
    386 		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
    387 		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
    388 		    set->cmd2 & CMD2_CLR ? " CLR" : "",
    389 		    set->cmd2 & CMD2_SET ? " SET" : "",
    390 		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
    391 		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
    392 		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
    393 }
    394 #endif
    395 
    396 /*
    397  * Given an array of bitcmd structures, compress by compacting consecutive
    398  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
    399  * 'g' and 'o' commands continue to be separate.  They could probably be
    400  * compacted, but it's not worth the effort.
    401  */
    402 static int
    403 compress_mode(set)
    404 	register BITCMD *set;
    405 {
    406 	register BITCMD *nset;
    407 	register int setbits, clrbits, Xbits, op;
    408 
    409 	for (nset = set;;) {
    410 		/* Copy over any 'u', 'g' and 'o' commands. */
    411 		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
    412 			*set++ = *nset++;
    413 			if (!op)
    414 				return;
    415 		}
    416 
    417 		for (setbits = clrbits = Xbits = 0;; nset++) {
    418 			if ((op = nset->cmd) == '-') {
    419 				clrbits |= nset->bits;
    420 				setbits &= ~nset->bits;
    421 				Xbits &= ~nset->bits;
    422 			} else if (op == '+') {
    423 				setbits |= nset->bits;
    424 				clrbits &= ~nset->bits;
    425 				Xbits &= ~nset->bits;
    426 			} else if (op == 'X')
    427 				Xbits |= nset->bits & ~setbits;
    428 			else
    429 				break;
    430 		}
    431 		if (clrbits) {
    432 			set->cmd = '-';
    433 			set->cmd2 = 0;
    434 			set->bits = clrbits;
    435 			set++;
    436 		}
    437 		if (setbits) {
    438 			set->cmd = '+';
    439 			set->cmd2 = 0;
    440 			set->bits = setbits;
    441 			set++;
    442 		}
    443 		if (Xbits) {
    444 			set->cmd = 'X';
    445 			set->cmd2 = 0;
    446 			set->bits = Xbits;
    447 			set++;
    448 		}
    449 	}
    450 }
    451