gen/FreeBSD/setmode.c

   1 /*
   2  * Copyright (c) 1989, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Dave Borman at Cray Research, Inc.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)setmode.c   8.2 (Berkeley) 3/25/94";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/gen/setmode.c,v 1.9 2003/02/23 00:24:03 mikeh Exp $");
  42
  43 #include "namespace.h"
  44 #include <sys/types.h>
  45 #include <sys/stat.h>
  46
  47 #include <ctype.h>
  48 #include <signal.h>
  49 #include <stddef.h>
  50 #include <stdlib.h>
  51 #include <unistd.h>
  52
  53 #ifdef SETMODE_DEBUG
  54 #include <stdio.h>
  55 #endif
  56 #include "un-namespace.h"
  57
  58 #define SET_LEN 6               /* initial # of bitcmd struct to malloc */
  59 #define SET_LEN_INCR 4          /* # of bitcmd structs to add as needed */
  60
  61 typedef struct bitcmd {
  62         char    cmd;
  63         char    cmd2;
  64         mode_t  bits;
  65 } BITCMD;
  66
  67 #define CMD2_CLR        0x01
  68 #define CMD2_SET        0x02
  69 #define CMD2_GBITS      0x04
  70 #define CMD2_OBITS      0x08
  71 #define CMD2_UBITS      0x10
  72
  73 static BITCMD   *addcmd(BITCMD *, int, int, int, u_int);
  74 static void      compress_mode(BITCMD *);
  75 #ifdef SETMODE_DEBUG
  76 static void      dumpmode(BITCMD *);
  77 #endif
  78
  79 /*
  80  * Given the old mode and an array of bitcmd structures, apply the operations
  81  * described in the bitcmd structures to the old mode, and return the new mode.
  82  * Note that there is no '=' command; a strict assignment is just a '-' (clear
  83  * bits) followed by a '+' (set bits).
  84  */
  85 mode_t
  86 getmode(bbox, omode)
  87         const void *bbox;
  88         mode_t omode;
  89 {
  90         const BITCMD *set;
  91         mode_t clrval, newmode, value;
  92
  93         set = (const BITCMD *)bbox;
  94         newmode = omode;
  95         for (value = 0;; set++)
  96                 switch(set->cmd) {
  97                 /*
  98                  * When copying the user, group or other bits around, we "know"
  99                  * where the bits are in the mode so that we can do shifts to
 100                  * copy them around.  If we don't use shifts, it gets real
 101                  * grundgy with lots of single bit checks and bit sets.
 102                  */
 103                 case 'u':
 104                         value = (newmode & S_IRWXU) >> 6;
 105                         goto common;
 106
 107                 case 'g':
 108                         value = (newmode & S_IRWXG) >> 3;
 109                         goto common;
 110
 111                 case 'o':
 112                         value = newmode & S_IRWXO;
 113 common:                 if (set->cmd2 & CMD2_CLR) {
 114                                 clrval =
 115                                     (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
 116                                 if (set->cmd2 & CMD2_UBITS)
 117                                         newmode &= ~((clrval<<6) & set->bits);
 118                                 if (set->cmd2 & CMD2_GBITS)
 119                                         newmode &= ~((clrval<<3) & set->bits);
 120                                 if (set->cmd2 & CMD2_OBITS)
 121                                         newmode &= ~(clrval & set->bits);
 122                         }
 123                         if (set->cmd2 & CMD2_SET) {
 124                                 if (set->cmd2 & CMD2_UBITS)
 125                                         newmode |= (value<<6) & set->bits;
 126                                 if (set->cmd2 & CMD2_GBITS)
 127                                         newmode |= (value<<3) & set->bits;
 128                                 if (set->cmd2 & CMD2_OBITS)
 129                                         newmode |= value & set->bits;
 130                         }
 131                         break;
 132
 133                 case '+':
 134                         newmode |= set->bits;
 135                         break;
 136
 137                 case '-':
 138                         newmode &= ~set->bits;
 139                         break;
 140
 141                 case 'X':
 142                         if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
 143                                 newmode |= set->bits;
 144                         break;
 145
 146                 case '\0':
 147                 default:
 148 #ifdef SETMODE_DEBUG
 149                         (void)printf("getmode:%04o -> %04o\n", omode, newmode);
 150 #endif
 151                         return (newmode);
 152                 }
 153 }
 154
 155 #define ADDCMD(a, b, c, d)                                              \
 156         if (set >= endset) {                                            \
 157                 BITCMD *newset;                                         \
 158                 setlen += SET_LEN_INCR;                                 \
 159                 newset = realloc(saveset, sizeof(BITCMD) * setlen);     \
 160                 if (!newset) {                                          \
 161                         if (saveset)                                    \
 162                                 free(saveset);                          \
 163                         saveset = NULL;                                 \
 164                         return (NULL);                                  \
 165                 }                                                       \
 166                 set = newset + (set - saveset);                         \
 167                 saveset = newset;                                       \
 168                 endset = newset + (setlen - 2);                         \
 169         }                                                               \
 170         set = addcmd(set, (a), (b), (c), (d))
 171
 172 #define STANDARD_BITS   (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
 173
 174 void *
 175 setmode(p)
 176         const char *p;
 177 {
 178         int perm, who;
 179         char op, *ep;
 180         BITCMD *set, *saveset, *endset;
 181         sigset_t sigset, sigoset;
 182         mode_t mask;
 183         int equalopdone=0, permXbits, setlen;
 184         long perml;
 185
 186         if (!*p)
 187                 return (NULL);
 188
 189         /*
 190          * Get a copy of the mask for the permissions that are mask relative.
 191          * Flip the bits, we want what's not set.  Since it's possible that
 192          * the caller is opening files inside a signal handler, protect them
 193          * as best we can.
 194          */
 195         sigfillset(&sigset);
 196         (void)_sigprocmask(SIG_BLOCK, &sigset, &sigoset);
 197         (void)umask(mask = umask(0));
 198         mask = ~mask;
 199         (void)_sigprocmask(SIG_SETMASK, &sigoset, NULL);
 200
 201         setlen = SET_LEN + 2;
 202
 203         if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
 204                 return (NULL);
 205         saveset = set;
 206         endset = set + (setlen - 2);
 207
 208         /*
 209          * If an absolute number, get it and return; disallow non-octal digits
 210          * or illegal bits.
 211          */
 212         if (isdigit((unsigned char)*p)) {
 213                 perml = strtol(p, &ep, 8);
 214                 if (*ep || perml < 0 || perml & ~(STANDARD_BITS|S_ISTXT)) {
 215                         free(saveset);
 216                         return (NULL);
 217                 }
 218                 perm = (mode_t)perml;
 219                 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
 220                 set->cmd = 0;
 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 || who & ~S_IRWXO)
 265                                         perm |= S_ISUID|S_ISGID;
 266                                 break;
 267                         case 't':
 268                                 /* If only "other" bits ignore sticky. */
 269                                 if (!who || 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         int oparg, who;
 346         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 = (mode_t)~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         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 void
 412 compress_mode(set)
 413         BITCMD *set;
 414 {
 415         BITCMD *nset;
 416         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 }