src/chmod.c

   1 /* chmod -- change permission modes of files
   2    Copyright (C) 1989-2012 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by David MacKenzie <djm@gnu.ai.mit.edu> */
  18
  19 #include <config.h>
  20 #include <stdio.h>
  21 #include <getopt.h>
  22 #include <sys/types.h>
  23
  24 #include "system.h"
  25 #include "dev-ino.h"
  26 #include "error.h"
  27 #include "filemode.h"
  28 #include "ignore-value.h"
  29 #include "modechange.h"
  30 #include "quote.h"
  31 #include "quotearg.h"
  32 #include "root-dev-ino.h"
  33 #include "xfts.h"
  34
  35 /* The official name of this program (e.g., no 'g' prefix).  */
  36 #define PROGRAM_NAME "chmod"
  37
  38 #define AUTHORS \
  39   proper_name ("David MacKenzie"), \
  40   proper_name ("Jim Meyering")
  41
  42 enum Change_status
  43 {
  44   CH_NOT_APPLIED,
  45   CH_SUCCEEDED,
  46   CH_FAILED,
  47   CH_NO_CHANGE_REQUESTED
  48 };
  49
  50 enum Verbosity
  51 {
  52   /* Print a message for each file that is processed.  */
  53   V_high,
  54
  55   /* Print a message for each file whose attributes we change.  */
  56   V_changes_only,
  57
  58   /* Do not be verbose.  This is the default. */
  59   V_off
  60 };
  61
  62 /* The desired change to the mode.  */
  63 static struct mode_change *change;
  64
  65 /* The initial umask value, if it might be needed.  */
  66 static mode_t umask_value;
  67
  68 /* If true, change the modes of directories recursively. */
  69 static bool recurse;
  70
  71 /* If true, force silence (suppress most of error messages). */
  72 static bool force_silent;
  73
  74 /* If true, diagnose surprises from naive misuses like "chmod -r file".
  75    POSIX allows diagnostics here, as portable code is supposed to use
  76    "chmod -- -r file".  */
  77 static bool diagnose_surprises;
  78
  79 /* Level of verbosity.  */
  80 static enum Verbosity verbosity = V_off;
  81
  82 /* Pointer to the device and inode numbers of '/', when --recursive.
  83    Otherwise NULL.  */
  84 static struct dev_ino *root_dev_ino;
  85
  86 /* For long options that have no equivalent short option, use a
  87    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
  88 enum
  89 {
  90   NO_PRESERVE_ROOT = CHAR_MAX + 1,
  91   PRESERVE_ROOT,
  92   REFERENCE_FILE_OPTION
  93 };
  94
  95 static struct option const long_options[] =
  96 {
  97   {"changes", no_argument, NULL, 'c'},
  98   {"recursive", no_argument, NULL, 'R'},
  99   {"no-preserve-root", no_argument, NULL, NO_PRESERVE_ROOT},
 100   {"preserve-root", no_argument, NULL, PRESERVE_ROOT},
 101   {"quiet", no_argument, NULL, 'f'},
 102   {"reference", required_argument, NULL, REFERENCE_FILE_OPTION},
 103   {"silent", no_argument, NULL, 'f'},
 104   {"verbose", no_argument, NULL, 'v'},
 105   {GETOPT_HELP_OPTION_DECL},
 106   {GETOPT_VERSION_OPTION_DECL},
 107   {NULL, 0, NULL, 0}
 108 };
 109
 110 /* Return true if the chmodable permission bits of FILE changed.
 111    The old mode was OLD_MODE, but it was changed to NEW_MODE.  */
 112
 113 static bool
 114 mode_changed (char const *file, mode_t old_mode, mode_t new_mode)
 115 {
 116   if (new_mode & (S_ISUID | S_ISGID | S_ISVTX))
 117     {
 118       /* The new mode contains unusual bits that the call to chmod may
 119          have silently cleared.  Check whether they actually changed.  */
 120
 121       struct stat new_stats;
 122
 123       if (stat (file, &new_stats) != 0)
 124         {
 125           if (! force_silent)
 126             error (0, errno, _("getting new attributes of %s"), quote (file));
 127           return false;
 128         }
 129
 130       new_mode = new_stats.st_mode;
 131     }
 132
 133   return ((old_mode ^ new_mode) & CHMOD_MODE_BITS) != 0;
 134 }
 135
 136 /* Tell the user how/if the MODE of FILE has been changed.
 137    CHANGED describes what (if anything) has happened. */
 138
 139 static void
 140 describe_change (const char *file, mode_t old_mode, mode_t mode,
 141                  enum Change_status changed)
 142 {
 143   char perms[12];               /* "-rwxrwxrwx" ls-style modes. */
 144   char old_perms[12];
 145   const char *fmt;
 146
 147   if (changed == CH_NOT_APPLIED)
 148     {
 149       printf (_("neither symbolic link %s nor referent has been changed\n"),
 150               quote (file));
 151       return;
 152     }
 153
 154   strmode (mode, perms);
 155   perms[10] = '\0';             /* Remove trailing space.  */
 156
 157   strmode (old_mode, old_perms);
 158   old_perms[10] = '\0';         /* Remove trailing space.  */
 159
 160   switch (changed)
 161     {
 162     case CH_SUCCEEDED:
 163       fmt = _("mode of %s changed from %04lo (%s) to %04lo (%s)\n");
 164       break;
 165     case CH_FAILED:
 166       fmt = _("failed to change mode of %s from %04lo (%s) to %04lo (%s)\n");
 167       break;
 168     case CH_NO_CHANGE_REQUESTED:
 169       fmt = _("mode of %s retained as %04lo (%s)\n");
 170       printf (fmt, quote (file),
 171               (unsigned long int) (mode & CHMOD_MODE_BITS), &perms[1]);
 172       return;
 173     default:
 174       abort ();
 175     }
 176   printf (fmt, quote (file),
 177           (unsigned long int) (old_mode & CHMOD_MODE_BITS), &old_perms[1],
 178           (unsigned long int) (mode & CHMOD_MODE_BITS), &perms[1]);
 179 }
 180
 181 /* Change the mode of FILE.
 182    Return true if successful.  This function is called
 183    once for every file system object that fts encounters.  */
 184
 185 static bool
 186 process_file (FTS *fts, FTSENT *ent)
 187 {
 188   char const *file_full_name = ent->fts_path;
 189   char const *file = ent->fts_accpath;
 190   const struct stat *file_stats = ent->fts_statp;
 191   mode_t old_mode IF_LINT ( = 0);
 192   mode_t new_mode IF_LINT ( = 0);
 193   bool ok = true;
 194   bool chmod_succeeded = false;
 195
 196   switch (ent->fts_info)
 197     {
 198     case FTS_DP:
 199       return true;
 200
 201     case FTS_NS:
 202       /* For a top-level file or directory, this FTS_NS (stat failed)
 203          indicator is determined at the time of the initial fts_open call.
 204          With programs like chmod, chown, and chgrp, that modify
 205          permissions, it is possible that the file in question is
 206          accessible when control reaches this point.  So, if this is
 207          the first time we've seen the FTS_NS for this file, tell
 208          fts_read to stat it "again".  */
 209       if (ent->fts_level == 0 && ent->fts_number == 0)
 210         {
 211           ent->fts_number = 1;
 212           fts_set (fts, ent, FTS_AGAIN);
 213           return true;
 214         }
 215       if (! force_silent)
 216         error (0, ent->fts_errno, _("cannot access %s"),
 217                quote (file_full_name));
 218       ok = false;
 219       break;
 220
 221     case FTS_ERR:
 222       if (! force_silent)
 223         error (0, ent->fts_errno, "%s", quote (file_full_name));
 224       ok = false;
 225       break;
 226
 227     case FTS_DNR:
 228       if (! force_silent)
 229         error (0, ent->fts_errno, _("cannot read directory %s"),
 230                quote (file_full_name));
 231       ok = false;
 232       break;
 233
 234     case FTS_SLNONE:
 235       if (! force_silent)
 236         error (0, 0, _("cannot operate on dangling symlink %s"),
 237                quote (file_full_name));
 238       ok = false;
 239       break;
 240
 241     case FTS_DC:                /* directory that causes cycles */
 242       if (cycle_warning_required (fts, ent))
 243         {
 244           emit_cycle_warning (file_full_name);
 245           return false;
 246         }
 247       break;
 248
 249     default:
 250       break;
 251     }
 252
 253   if (ok && ROOT_DEV_INO_CHECK (root_dev_ino, file_stats))
 254     {
 255       ROOT_DEV_INO_WARN (file_full_name);
 256       /* Tell fts not to traverse into this hierarchy.  */
 257       fts_set (fts, ent, FTS_SKIP);
 258       /* Ensure that we do not process "/" on the second visit.  */
 259       ignore_value (fts_read (fts));
 260       return false;
 261     }
 262
 263   if (ok)
 264     {
 265       old_mode = file_stats->st_mode;
 266       new_mode = mode_adjust (old_mode, S_ISDIR (old_mode) != 0, umask_value,
 267                               change, NULL);
 268
 269       if (! S_ISLNK (old_mode))
 270         {
 271           if (chmodat (fts->fts_cwd_fd, file, new_mode) == 0)
 272             chmod_succeeded = true;
 273           else
 274             {
 275               if (! force_silent)
 276                 error (0, errno, _("changing permissions of %s"),
 277                        quote (file_full_name));
 278               ok = false;
 279             }
 280         }
 281     }
 282
 283   if (verbosity != V_off)
 284     {
 285       bool changed = (chmod_succeeded
 286                       && mode_changed (file, old_mode, new_mode));
 287
 288       if (changed || verbosity == V_high)
 289         {
 290           enum Change_status ch_status =
 291             (!ok ? CH_FAILED
 292              : !chmod_succeeded ? CH_NOT_APPLIED
 293              : !changed ? CH_NO_CHANGE_REQUESTED
 294              : CH_SUCCEEDED);
 295           describe_change (file_full_name, old_mode, new_mode, ch_status);
 296         }
 297     }
 298
 299   if (chmod_succeeded && diagnose_surprises)
 300     {
 301       mode_t naively_expected_mode =
 302         mode_adjust (old_mode, S_ISDIR (old_mode) != 0, 0, change, NULL);
 303       if (new_mode & ~naively_expected_mode)
 304         {
 305           char new_perms[12];
 306           char naively_expected_perms[12];
 307           strmode (new_mode, new_perms);
 308           strmode (naively_expected_mode, naively_expected_perms);
 309           new_perms[10] = naively_expected_perms[10] = '\0';
 310           error (0, 0,
 311                  _("%s: new permissions are %s, not %s"),
 312                  quotearg_colon (file_full_name),
 313                  new_perms + 1, naively_expected_perms + 1);
 314           ok = false;
 315         }
 316     }
 317
 318   if ( ! recurse)
 319     fts_set (fts, ent, FTS_SKIP);
 320
 321   return ok;
 322 }
 323
 324 /* Recursively change the modes of the specified FILES (the last entry
 325    of which is NULL).  BIT_FLAGS controls how fts works.
 326    Return true if successful.  */
 327
 328 static bool
 329 process_files (char **files, int bit_flags)
 330 {
 331   bool ok = true;
 332
 333   FTS *fts = xfts_open (files, bit_flags, NULL);
 334
 335   while (1)
 336     {
 337       FTSENT *ent;
 338
 339       ent = fts_read (fts);
 340       if (ent == NULL)
 341         {
 342           if (errno != 0)
 343             {
 344               /* FIXME: try to give a better message  */
 345               if (! force_silent)
 346                 error (0, errno, _("fts_read failed"));
 347               ok = false;
 348             }
 349           break;
 350         }
 351
 352       ok &= process_file (fts, ent);
 353     }
 354
 355   if (fts_close (fts) != 0)
 356     {
 357       error (0, errno, _("fts_close failed"));
 358       ok = false;
 359     }
 360
 361   return ok;
 362 }
 363
 364 void
 365 usage (int status)
 366 {
 367   if (status != EXIT_SUCCESS)
 368     emit_try_help ();
 369   else
 370     {
 371       printf (_("\
 372 Usage: %s [OPTION]... MODE[,MODE]... FILE...\n\
 373   or:  %s [OPTION]... OCTAL-MODE FILE...\n\
 374   or:  %s [OPTION]... --reference=RFILE FILE...\n\
 375 "),
 376               program_name, program_name, program_name);
 377       fputs (_("\
 378 Change the mode of each FILE to MODE.\n\
 379 With --reference, change the mode of each FILE to that of RFILE.\n\
 380 \n\
 381 "), stdout);
 382       fputs (_("\
 383   -c, --changes          like verbose but report only when a change is made\n\
 384   -f, --silent, --quiet  suppress most error messages\n\
 385   -v, --verbose          output a diagnostic for every file processed\n\
 386 "), stdout);
 387       fputs (_("\
 388       --no-preserve-root  do not treat '/' specially (the default)\n\
 389       --preserve-root    fail to operate recursively on '/'\n\
 390 "), stdout);
 391       fputs (_("\
 392       --reference=RFILE  use RFILE's mode instead of MODE values\n\
 393 "), stdout);
 394       fputs (_("\
 395   -R, --recursive        change files and directories recursively\n\
 396 "), stdout);
 397       fputs (HELP_OPTION_DESCRIPTION, stdout);
 398       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 399       fputs (_("\
 400 \n\
 401 Each MODE is of the form '[ugoa]*([-+=]([rwxXst]*|[ugo]))+|[-+=][0-7]+'.\n\
 402 "), stdout);
 403       emit_ancillary_info ();
 404     }
 405   exit (status);
 406 }
 407
 408 /* Parse the ASCII mode given on the command line into a linked list
 409    of 'struct mode_change' and apply that to each file argument. */
 410
 411 int
 412 main (int argc, char **argv)
 413 {
 414   char *mode = NULL;
 415   size_t mode_len = 0;
 416   size_t mode_alloc = 0;
 417   bool ok;
 418   bool preserve_root = false;
 419   char const *reference_file = NULL;
 420   int c;
 421
 422   initialize_main (&argc, &argv);
 423   set_program_name (argv[0]);
 424   setlocale (LC_ALL, "");
 425   bindtextdomain (PACKAGE, LOCALEDIR);
 426   textdomain (PACKAGE);
 427
 428   atexit (close_stdout);
 429
 430   recurse = force_silent = diagnose_surprises = false;
 431
 432   while ((c = getopt_long (argc, argv,
 433                            ("Rcfvr::w::x::X::s::t::u::g::o::a::,::+::=::"
 434                             "0::1::2::3::4::5::6::7::"),
 435                            long_options, NULL))
 436          != -1)
 437     {
 438       switch (c)
 439         {
 440         case 'r':
 441         case 'w':
 442         case 'x':
 443         case 'X':
 444         case 's':
 445         case 't':
 446         case 'u':
 447         case 'g':
 448         case 'o':
 449         case 'a':
 450         case ',':
 451         case '+':
 452         case '=':
 453         case '0': case '1': case '2': case '3':
 454         case '4': case '5': case '6': case '7':
 455           /* Support nonportable uses like "chmod -w", but diagnose
 456              surprises due to umask confusion.  Even though "--", "--r",
 457              etc., are valid modes, there is no "case '-'" here since
 458              getopt_long reserves leading "--" for long options.  */
 459           {
 460             /* Allocate a mode string (e.g., "-rwx") by concatenating
 461                the argument containing this option.  If a previous mode
 462                string was given, concatenate the previous string, a
 463                comma, and the new string (e.g., "-s,-rwx").  */
 464
 465             char const *arg = argv[optind - 1];
 466             size_t arg_len = strlen (arg);
 467             size_t mode_comma_len = mode_len + !!mode_len;
 468             size_t new_mode_len = mode_comma_len + arg_len;
 469             if (mode_alloc <= new_mode_len)
 470               {
 471                 mode_alloc = new_mode_len + 1;
 472                 mode = X2REALLOC (mode, &mode_alloc);
 473               }
 474             mode[mode_len] = ',';
 475             memcpy (mode + mode_comma_len, arg, arg_len + 1);
 476             mode_len = new_mode_len;
 477
 478             diagnose_surprises = true;
 479           }
 480           break;
 481         case NO_PRESERVE_ROOT:
 482           preserve_root = false;
 483           break;
 484         case PRESERVE_ROOT:
 485           preserve_root = true;
 486           break;
 487         case REFERENCE_FILE_OPTION:
 488           reference_file = optarg;
 489           break;
 490         case 'R':
 491           recurse = true;
 492           break;
 493         case 'c':
 494           verbosity = V_changes_only;
 495           break;
 496         case 'f':
 497           force_silent = true;
 498           break;
 499         case 'v':
 500           verbosity = V_high;
 501           break;
 502         case_GETOPT_HELP_CHAR;
 503         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 504         default:
 505           usage (EXIT_FAILURE);
 506         }
 507     }
 508
 509   if (reference_file)
 510     {
 511       if (mode)
 512         {
 513           error (0, 0, _("cannot combine mode and --reference options"));
 514           usage (EXIT_FAILURE);
 515         }
 516     }
 517   else
 518     {
 519       if (!mode)
 520         mode = argv[optind++];
 521     }
 522
 523   if (optind >= argc)
 524     {
 525       if (!mode || mode != argv[optind - 1])
 526         error (0, 0, _("missing operand"));
 527       else
 528         error (0, 0, _("missing operand after %s"), quote (argv[argc - 1]));
 529       usage (EXIT_FAILURE);
 530     }
 531
 532   if (reference_file)
 533     {
 534       change = mode_create_from_ref (reference_file);
 535       if (!change)
 536         error (EXIT_FAILURE, errno, _("failed to get attributes of %s"),
 537                quote (reference_file));
 538     }
 539   else
 540     {
 541       change = mode_compile (mode);
 542       if (!change)
 543         {
 544           error (0, 0, _("invalid mode: %s"), quote (mode));
 545           usage (EXIT_FAILURE);
 546         }
 547       umask_value = umask (0);
 548     }
 549
 550   if (recurse && preserve_root)
 551     {
 552       static struct dev_ino dev_ino_buf;
 553       root_dev_ino = get_root_dev_ino (&dev_ino_buf);
 554       if (root_dev_ino == NULL)
 555         error (EXIT_FAILURE, errno, _("failed to get attributes of %s"),
 556                quote ("/"));
 557     }
 558   else
 559     {
 560       root_dev_ino = NULL;
 561     }
 562
 563   ok = process_files (argv + optind,
 564                       FTS_COMFOLLOW | FTS_PHYSICAL | FTS_DEFER_STAT);
 565
 566   exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
 567 }