lib/libc/gen/setmode.c

   1 /*      $NetBSD: setmode.c,v 1.30 2003/08/07 16:42:56 agc 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. 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 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)setmode.c   8.2 (Berkeley) 3/25/94";
  39 #else
  40 __RCSID("$NetBSD: setmode.c,v 1.30 2003/08/07 16:42:56 agc Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include "namespace.h"
  45 #include <sys/types.h>
  46 #include <sys/stat.h>
  47
  48 #include <assert.h>
  49 #include <ctype.h>
  50 #include <errno.h>
  51 #include <signal.h>
  52 #include <stdlib.h>
  53 #include <limits.h>
  54 #include <unistd.h>
  55
  56 #ifdef SETMODE_DEBUG
  57 #include <stdio.h>
  58 #endif
  59
  60 #ifdef __weak_alias
  61 __weak_alias(getmode,_getmode)
  62 __weak_alias(setmode,_setmode)
  63 #endif
  64
  65 #define SET_LEN 6               /* initial # of bitcmd struct to malloc */
  66 #define SET_LEN_INCR 4          /* # of bitcmd structs to add as needed */
  67
  68 typedef struct bitcmd {
  69         char    cmd;
  70         char    cmd2;
  71         mode_t  bits;
  72 } BITCMD;
  73
  74 #define CMD2_CLR        0x01
  75 #define CMD2_SET        0x02
  76 #define CMD2_GBITS      0x04
  77 #define CMD2_OBITS      0x08
  78 #define CMD2_UBITS      0x10
  79
  80 static BITCMD   *addcmd __P((BITCMD *, mode_t, mode_t, mode_t, mode_t));
  81 static void      compress_mode __P((BITCMD *));
  82 #ifdef SETMODE_DEBUG
  83 static void      dumpmode __P((BITCMD *));
  84 #endif
  85
  86 /*
  87  * Given the old mode and an array of bitcmd structures, apply the operations
  88  * described in the bitcmd structures to the old mode, and return the new mode.
  89  * Note that there is no '=' command; a strict assignment is just a '-' (clear
  90  * bits) followed by a '+' (set bits).
  91  */
  92 mode_t
  93 getmode(bbox, omode)
  94         const void *bbox;
  95         mode_t omode;
  96 {
  97         const BITCMD *set;
  98         mode_t clrval, newmode, value;
  99
 100         _DIAGASSERT(bbox != NULL);
 101
 102         set = (const BITCMD *)bbox;
 103         newmode = omode;
 104         for (value = 0;; set++)
 105                 switch(set->cmd) {
 106                 /*
 107                  * When copying the user, group or other bits around, we "know"
 108                  * where the bits are in the mode so that we can do shifts to
 109                  * copy them around.  If we don't use shifts, it gets real
 110                  * grundgy with lots of single bit checks and bit sets.
 111                  */
 112                 case 'u':
 113                         value = (newmode & S_IRWXU) >> 6;
 114                         goto common;
 115
 116                 case 'g':
 117                         value = (newmode & S_IRWXG) >> 3;
 118                         goto common;
 119
 120                 case 'o':
 121                         value = newmode & S_IRWXO;
 122 common:                 if (set->cmd2 & CMD2_CLR) {
 123                                 clrval =
 124                                     (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
 125                                 if (set->cmd2 & CMD2_UBITS)
 126                                         newmode &= ~((clrval<<6) & set->bits);
 127                                 if (set->cmd2 & CMD2_GBITS)
 128                                         newmode &= ~((clrval<<3) & set->bits);
 129                                 if (set->cmd2 & CMD2_OBITS)
 130                                         newmode &= ~(clrval & set->bits);
 131                         }
 132                         if (set->cmd2 & CMD2_SET) {
 133                                 if (set->cmd2 & CMD2_UBITS)
 134                                         newmode |= (value<<6) & set->bits;
 135                                 if (set->cmd2 & CMD2_GBITS)
 136                                         newmode |= (value<<3) & set->bits;
 137                                 if (set->cmd2 & CMD2_OBITS)
 138                                         newmode |= value & set->bits;
 139                         }
 140                         break;
 141
 142                 case '+':
 143                         newmode |= set->bits;
 144                         break;
 145
 146                 case '-':
 147                         newmode &= ~set->bits;
 148                         break;
 149
 150                 case 'X':
 151                         if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
 152                                 newmode |= set->bits;
 153                         break;
 154
 155                 case '\0':
 156                 default:
 157 #ifdef SETMODE_DEBUG
 158                         (void)printf("getmode:%04o -> %04o\n", omode, newmode);
 159 #endif
 160                         return (newmode);
 161                 }
 162 }
 163
 164 #define ADDCMD(a, b, c, d) do {                                         \
 165         if (set >= endset) {                                            \
 166                 BITCMD *newset;                                         \
 167                 setlen += SET_LEN_INCR;                                 \
 168                 newset = realloc(saveset, sizeof(BITCMD) * setlen);     \
 169                 if (newset == NULL)                                     \
 170                         goto out;                                       \
 171                 set = newset + (set - saveset);                         \
 172                 saveset = newset;                                       \
 173                 endset = newset + (setlen - 2);                         \
 174         }                                                               \
 175         set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d));  \
 176 } while (/*CONSTCOND*/0)
 177
 178 #define STANDARD_BITS   (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
 179
 180 void *
 181 setmode(p)
 182         const char *p;
 183 {
 184         int serrno;
 185         char op, *ep;
 186         BITCMD *set, *saveset, *endset;
 187         sigset_t signset, sigoset;
 188         mode_t mask, perm, permXbits, who;
 189         long lval;
 190         int equalopdone = 0;    /* pacify gcc */
 191         int setlen;
 192
 193         if (!*p) {
 194                 errno = EINVAL;
 195                 return NULL;
 196         }
 197
 198         /*
 199          * Get a copy of the mask for the permissions that are mask relative.
 200          * Flip the bits, we want what's not set.  Since it's possible that
 201          * the caller is opening files inside a signal handler, protect them
 202          * as best we can.
 203          */
 204         sigfillset(&signset);
 205         (void)sigprocmask(SIG_BLOCK, &signset, &sigoset);
 206         (void)umask(mask = umask(0));
 207         mask = ~mask;
 208         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
 209
 210         setlen = SET_LEN + 2;
 211
 212         if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
 213                 return (NULL);
 214         saveset = set;
 215         endset = set + (setlen - 2);
 216
 217         /*
 218          * If an absolute number, get it and return; disallow non-octal digits
 219          * or illegal bits.
 220          */
 221         if (isdigit((unsigned char)*p)) {
 222                 errno = 0;
 223                 lval = strtol(p, &ep, 8);
 224                 if (*ep) {
 225                         errno = EINVAL;
 226                         goto out;
 227                 }
 228                 if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
 229                         goto out;
 230                 if (lval & ~(STANDARD_BITS|S_ISTXT)) {
 231                         errno = EINVAL;
 232                         goto out;
 233                 }
 234                 perm = (mode_t)lval;
 235                 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
 236                 set->cmd = 0;
 237                 return (saveset);
 238         }
 239
 240         /*
 241          * Build list of structures to set/clear/copy bits as described by
 242          * each clause of the symbolic mode.
 243          */
 244         for (;;) {
 245                 /* First, find out which bits might be modified. */
 246                 for (who = 0;; ++p) {
 247                         switch (*p) {
 248                         case 'a':
 249                                 who |= STANDARD_BITS;
 250                                 break;
 251                         case 'u':
 252                                 who |= S_ISUID|S_IRWXU;
 253                                 break;
 254                         case 'g':
 255                                 who |= S_ISGID|S_IRWXG;
 256                                 break;
 257                         case 'o':
 258                                 who |= S_IRWXO;
 259                                 break;
 260                         default:
 261                                 goto getop;
 262                         }
 263                 }
 264
 265 getop:          if ((op = *p++) != '+' && op != '-' && op != '=') {
 266                         errno = EINVAL;
 267                         goto out;
 268                 }
 269                 if (op == '=')
 270                         equalopdone = 0;
 271
 272                 who &= ~S_ISTXT;
 273                 for (perm = 0, permXbits = 0;; ++p) {
 274                         switch (*p) {
 275                         case 'r':
 276                                 perm |= S_IRUSR|S_IRGRP|S_IROTH;
 277                                 break;
 278                         case 's':
 279                                 /*
 280                                  * If specific bits where requested and
 281                                  * only "other" bits ignore set-id.
 282                                  */
 283                                 if (who == 0 || (who & ~S_IRWXO))
 284                                         perm |= S_ISUID|S_ISGID;
 285                                 break;
 286                         case 't':
 287                                 /*
 288                                  * If specific bits where requested and
 289                                  * only "other" bits ignore set-id.
 290                                  */
 291                                 if (who == 0 || (who & ~S_IRWXO)) {
 292                                         who |= S_ISTXT;
 293                                         perm |= S_ISTXT;
 294                                 }
 295                                 break;
 296                         case 'w':
 297                                 perm |= S_IWUSR|S_IWGRP|S_IWOTH;
 298                                 break;
 299                         case 'X':
 300                                 permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
 301                                 break;
 302                         case 'x':
 303                                 perm |= S_IXUSR|S_IXGRP|S_IXOTH;
 304                                 break;
 305                         case 'u':
 306                         case 'g':
 307                         case 'o':
 308                                 /*
 309                                  * When ever we hit 'u', 'g', or 'o', we have
 310                                  * to flush out any partial mode that we have,
 311                                  * and then do the copying of the mode bits.
 312                                  */
 313                                 if (perm) {
 314                                         ADDCMD(op, who, perm, mask);
 315                                         perm = 0;
 316                                 }
 317                                 if (op == '=')
 318                                         equalopdone = 1;
 319                                 if (op == '+' && permXbits) {
 320                                         ADDCMD('X', who, permXbits, mask);
 321                                         permXbits = 0;
 322                                 }
 323                                 ADDCMD(*p, who, op, mask);
 324                                 break;
 325
 326                         default:
 327                                 /*
 328                                  * Add any permissions that we haven't already
 329                                  * done.
 330                                  */
 331                                 if (perm || (op == '=' && !equalopdone)) {
 332                                         if (op == '=')
 333                                                 equalopdone = 1;
 334                                         ADDCMD(op, who, perm, mask);
 335                                         perm = 0;
 336                                 }
 337                                 if (permXbits) {
 338                                         ADDCMD('X', who, permXbits, mask);
 339                                         permXbits = 0;
 340                                 }
 341                                 goto apply;
 342                         }
 343                 }
 344
 345 apply:          if (!*p)
 346                         break;
 347                 if (*p != ',')
 348                         goto getop;
 349                 ++p;
 350         }
 351         set->cmd = 0;
 352 #ifdef SETMODE_DEBUG
 353         (void)printf("Before compress_mode()\n");
 354         dumpmode(saveset);
 355 #endif
 356         compress_mode(saveset);
 357 #ifdef SETMODE_DEBUG
 358         (void)printf("After compress_mode()\n");
 359         dumpmode(saveset);
 360 #endif
 361         return (saveset);
 362 out:
 363         serrno = errno;
 364         free(saveset);
 365         errno = serrno;
 366         return NULL;
 367 }
 368
 369 static BITCMD *
 370 addcmd(set, op, who, oparg, mask)
 371         BITCMD *set;
 372         mode_t oparg, who, op, mask;
 373 {
 374
 375         _DIAGASSERT(set != NULL);
 376
 377         switch (op) {
 378         case '=':
 379                 set->cmd = '-';
 380                 set->bits = who ? who : STANDARD_BITS;
 381                 set++;
 382
 383                 op = '+';
 384                 /* FALLTHROUGH */
 385         case '+':
 386         case '-':
 387         case 'X':
 388                 set->cmd = op;
 389                 set->bits = (who ? who : mask) & oparg;
 390                 break;
 391
 392         case 'u':
 393         case 'g':
 394         case 'o':
 395                 set->cmd = op;
 396                 if (who) {
 397                         set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
 398                                     ((who & S_IRGRP) ? CMD2_GBITS : 0) |
 399                                     ((who & S_IROTH) ? CMD2_OBITS : 0);
 400                         set->bits = (mode_t)~0;
 401                 } else {
 402                         set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
 403                         set->bits = mask;
 404                 }
 405
 406                 if (oparg == '+')
 407                         set->cmd2 |= CMD2_SET;
 408                 else if (oparg == '-')
 409                         set->cmd2 |= CMD2_CLR;
 410                 else if (oparg == '=')
 411                         set->cmd2 |= CMD2_SET|CMD2_CLR;
 412                 break;
 413         }
 414         return (set + 1);
 415 }
 416
 417 #ifdef SETMODE_DEBUG
 418 static void
 419 dumpmode(set)
 420         BITCMD *set;
 421 {
 422
 423         _DIAGASSERT(set != NULL);
 424
 425         for (; set->cmd; ++set)
 426                 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
 427                     set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
 428                     set->cmd2 & CMD2_CLR ? " CLR" : "",
 429                     set->cmd2 & CMD2_SET ? " SET" : "",
 430                     set->cmd2 & CMD2_UBITS ? " UBITS" : "",
 431                     set->cmd2 & CMD2_GBITS ? " GBITS" : "",
 432                     set->cmd2 & CMD2_OBITS ? " OBITS" : "");
 433 }
 434 #endif
 435
 436 /*
 437  * Given an array of bitcmd structures, compress by compacting consecutive
 438  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
 439  * 'g' and 'o' commands continue to be separate.  They could probably be
 440  * compacted, but it's not worth the effort.
 441  */
 442 static void
 443 compress_mode(set)
 444         BITCMD *set;
 445 {
 446         BITCMD *nset;
 447         int setbits, clrbits, Xbits, op;
 448
 449         _DIAGASSERT(set != NULL);
 450
 451         for (nset = set;;) {
 452                 /* Copy over any 'u', 'g' and 'o' commands. */
 453                 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
 454                         *set++ = *nset++;
 455                         if (!op)
 456                                 return;
 457                 }
 458
 459                 for (setbits = clrbits = Xbits = 0;; nset++) {
 460                         if ((op = nset->cmd) == '-') {
 461                                 clrbits |= nset->bits;
 462                                 setbits &= ~nset->bits;
 463                                 Xbits &= ~nset->bits;
 464                         } else if (op == '+') {
 465                                 setbits |= nset->bits;
 466                                 clrbits &= ~nset->bits;
 467                                 Xbits &= ~nset->bits;
 468                         } else if (op == 'X')
 469                                 Xbits |= nset->bits & ~setbits;
 470                         else
 471                                 break;
 472                 }
 473                 if (clrbits) {
 474                         set->cmd = '-';
 475                         set->cmd2 = 0;
 476                         set->bits = clrbits;
 477                         set++;
 478                 }
 479                 if (setbits) {
 480                         set->cmd = '+';
 481                         set->cmd2 = 0;
 482                         set->bits = setbits;
 483                         set++;
 484                 }
 485                 if (Xbits) {
 486                         set->cmd = 'X';
 487                         set->cmd2 = 0;
 488                         set->bits = Xbits;
 489                         set++;
 490                 }
 491         }
 492 }