src/chmod.c

   1 /* chmod -- change permission modes of files
   2    Copyright (C) 1989-1991, 1995-2010 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 mode,
 141                  enum Change_status changed)
 142 {
 143   char perms[12];               /* "-rwxrwxrwx" ls-style modes. */
 144   const char *fmt;
 145
 146   if (changed == CH_NOT_APPLIED)
 147     {
 148       printf (_("neither symbolic link %s nor referent has been changed\n"),
 149               quote (file));
 150       return;
 151     }
 152
 153   strmode (mode, perms);
 154   perms[10] = '\0';             /* Remove trailing space.  */
 155   switch (changed)
 156     {
 157     case CH_SUCCEEDED:
 158       fmt = _("mode of %s changed to %04lo (%s)\n");
 159       break;
 160     case CH_FAILED:
 161       fmt = _("failed to change mode of %s to %04lo (%s)\n");
 162       break;
 163     case CH_NO_CHANGE_REQUESTED:
 164       fmt = _("mode of %s retained as %04lo (%s)\n");
 165       break;
 166     default:
 167       abort ();
 168     }
 169   printf (fmt, quote (file),
 170           (unsigned long int) (mode & CHMOD_MODE_BITS), &perms[1]);
 171 }
 172
 173 /* Change the mode of FILE.
 174    Return true if successful.  This function is called
 175    once for every file system object that fts encounters.  */
 176
 177 static bool
 178 process_file (FTS *fts, FTSENT *ent)
 179 {
 180   char const *file_full_name = ent->fts_path;
 181   char const *file = ent->fts_accpath;
 182   const struct stat *file_stats = ent->fts_statp;
 183   mode_t old_mode IF_LINT ( = 0);
 184   mode_t new_mode IF_LINT ( = 0);
 185   bool ok = true;
 186   bool chmod_succeeded = false;
 187
 188   switch (ent->fts_info)
 189     {
 190     case FTS_DP:
 191       return true;
 192
 193     case FTS_NS:
 194       /* For a top-level file or directory, this FTS_NS (stat failed)
 195          indicator is determined at the time of the initial fts_open call.
 196          With programs like chmod, chown, and chgrp, that modify
 197          permissions, it is possible that the file in question is
 198          accessible when control reaches this point.  So, if this is
 199          the first time we've seen the FTS_NS for this file, tell
 200          fts_read to stat it "again".  */
 201       if (ent->fts_level == 0 && ent->fts_number == 0)
 202         {
 203           ent->fts_number = 1;
 204           fts_set (fts, ent, FTS_AGAIN);
 205           return true;
 206         }
 207       if (! force_silent)
 208         error (0, ent->fts_errno, _("cannot access %s"),
 209                quote (file_full_name));
 210       ok = false;
 211       break;
 212
 213     case FTS_ERR:
 214       if (! force_silent)
 215         error (0, ent->fts_errno, "%s", quote (file_full_name));
 216       ok = false;
 217       break;
 218
 219     case FTS_DNR:
 220       if (! force_silent)
 221         error (0, ent->fts_errno, _("cannot read directory %s"),
 222                quote (file_full_name));
 223       ok = false;
 224       break;
 225
 226     case FTS_SLNONE:
 227       if (! force_silent)
 228         error (0, 0, _("cannot operate on dangling symlink %s"),
 229                quote (file_full_name));
 230       ok = false;
 231       break;
 232
 233     case FTS_DC:                /* directory that causes cycles */
 234       if (cycle_warning_required (fts, ent))
 235         {
 236           emit_cycle_warning (file_full_name);
 237           return false;
 238         }
 239       break;
 240
 241     default:
 242       break;
 243     }
 244
 245   if (ok && ROOT_DEV_INO_CHECK (root_dev_ino, file_stats))
 246     {
 247       ROOT_DEV_INO_WARN (file_full_name);
 248       /* Tell fts not to traverse into this hierarchy.  */
 249       fts_set (fts, ent, FTS_SKIP);
 250       /* Ensure that we do not process "/" on the second visit.  */
 251       ignore_ptr (fts_read (fts));
 252       return false;
 253     }
 254
 255   if (ok)
 256     {
 257       old_mode = file_stats->st_mode;
 258       new_mode = mode_adjust (old_mode, S_ISDIR (old_mode) != 0, umask_value,
 259                               change, NULL);
 260
 261       if (! S_ISLNK (old_mode))
 262         {
 263           if (chmodat (fts->fts_cwd_fd, file, new_mode) == 0)
 264             chmod_succeeded = true;
 265           else
 266             {
 267               if (! force_silent)
 268                 error (0, errno, _("changing permissions of %s"),
 269                        quote (file_full_name));
 270               ok = false;
 271             }
 272         }
 273     }
 274
 275   if (verbosity != V_off)
 276     {
 277       bool changed = (chmod_succeeded
 278                       && mode_changed (file, old_mode, new_mode));
 279
 280       if (changed || verbosity == V_high)
 281         {
 282           enum Change_status ch_status =
 283             (!ok ? CH_FAILED
 284              : !chmod_succeeded ? CH_NOT_APPLIED
 285              : !changed ? CH_NO_CHANGE_REQUESTED
 286              : CH_SUCCEEDED);
 287           describe_change (file_full_name, new_mode, ch_status);
 288         }
 289     }
 290
 291   if (chmod_succeeded && diagnose_surprises)
 292     {
 293       mode_t naively_expected_mode =
 294         mode_adjust (old_mode, S_ISDIR (old_mode) != 0, 0, change, NULL);
 295       if (new_mode & ~naively_expected_mode)
 296         {
 297           char new_perms[12];
 298           char naively_expected_perms[12];
 299           strmode (new_mode, new_perms);
 300           strmode (naively_expected_mode, naively_expected_perms);
 301           new_perms[10] = naively_expected_perms[10] = '\0';
 302           error (0, 0,
 303                  _("%s: new permissions are %s, not %s"),
 304                  quotearg_colon (file_full_name),
 305                  new_perms + 1, naively_expected_perms + 1);
 306           ok = false;
 307         }
 308     }
 309
 310   if ( ! recurse)
 311     fts_set (fts, ent, FTS_SKIP);
 312
 313   return ok;
 314 }
 315
 316 /* Recursively change the modes of the specified FILES (the last entry
 317    of which is NULL).  BIT_FLAGS controls how fts works.
 318    Return true if successful.  */
 319
 320 static bool
 321 process_files (char **files, int bit_flags)
 322 {
 323   bool ok = true;
 324
 325   FTS *fts = xfts_open (files, bit_flags, NULL);
 326
 327   while (1)
 328     {
 329       FTSENT *ent;
 330
 331       ent = fts_read (fts);
 332       if (ent == NULL)
 333         {
 334           if (errno != 0)
 335             {
 336               /* FIXME: try to give a better message  */
 337               if (! force_silent)
 338                 error (0, errno, _("fts_read failed"));
 339               ok = false;
 340             }
 341           break;
 342         }
 343
 344       ok &= process_file (fts, ent);
 345     }
 346
 347   if (fts_close (fts) != 0)
 348     {
 349       error (0, errno, _("fts_close failed"));
 350       ok = false;
 351     }
 352
 353   return ok;
 354 }
 355
 356 void
 357 usage (int status)
 358 {
 359   if (status != EXIT_SUCCESS)
 360     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 361              program_name);
 362   else
 363     {
 364       printf (_("\
 365 Usage: %s [OPTION]... MODE[,MODE]... FILE...\n\
 366   or:  %s [OPTION]... OCTAL-MODE FILE...\n\
 367   or:  %s [OPTION]... --reference=RFILE FILE...\n\
 368 "),
 369               program_name, program_name, program_name);
 370       fputs (_("\
 371 Change the mode of each FILE to MODE.\n\
 372 \n\
 373   -c, --changes           like verbose but report only when a change is made\n\
 374 "), stdout);
 375       fputs (_("\
 376       --no-preserve-root  do not treat `/' specially (the default)\n\
 377       --preserve-root     fail to operate recursively on `/'\n\
 378 "), stdout);
 379       fputs (_("\
 380   -f, --silent, --quiet   suppress most error messages\n\
 381   -v, --verbose           output a diagnostic for every file processed\n\
 382       --reference=RFILE   use RFILE's mode instead of MODE values\n\
 383   -R, --recursive         change files and directories recursively\n\
 384 "), stdout);
 385       fputs (HELP_OPTION_DESCRIPTION, stdout);
 386       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 387       fputs (_("\
 388 \n\
 389 Each MODE is of the form `[ugoa]*([-+=]([rwxXst]*|[ugo]))+'.\n\
 390 "), stdout);
 391       emit_ancillary_info ();
 392     }
 393   exit (status);
 394 }
 395
 396 /* Parse the ASCII mode given on the command line into a linked list
 397    of `struct mode_change' and apply that to each file argument. */
 398
 399 int
 400 main (int argc, char **argv)
 401 {
 402   char *mode = NULL;
 403   size_t mode_len = 0;
 404   size_t mode_alloc = 0;
 405   bool ok;
 406   bool preserve_root = false;
 407   char const *reference_file = NULL;
 408   int c;
 409
 410   initialize_main (&argc, &argv);
 411   set_program_name (argv[0]);
 412   setlocale (LC_ALL, "");
 413   bindtextdomain (PACKAGE, LOCALEDIR);
 414   textdomain (PACKAGE);
 415
 416   atexit (close_stdout);
 417
 418   recurse = force_silent = diagnose_surprises = false;
 419
 420   while ((c = getopt_long (argc, argv,
 421                            "Rcfvr::w::x::X::s::t::u::g::o::a::,::+::=::",
 422                            long_options, NULL))
 423          != -1)
 424     {
 425       switch (c)
 426         {
 427         case 'r':
 428         case 'w':
 429         case 'x':
 430         case 'X':
 431         case 's':
 432         case 't':
 433         case 'u':
 434         case 'g':
 435         case 'o':
 436         case 'a':
 437         case ',':
 438         case '+':
 439         case '=':
 440           /* Support nonportable uses like "chmod -w", but diagnose
 441              surprises due to umask confusion.  Even though "--", "--r",
 442              etc., are valid modes, there is no "case '-'" here since
 443              getopt_long reserves leading "--" for long options.  */
 444           {
 445             /* Allocate a mode string (e.g., "-rwx") by concatenating
 446                the argument containing this option.  If a previous mode
 447                string was given, concatenate the previous string, a
 448                comma, and the new string (e.g., "-s,-rwx").  */
 449
 450             char const *arg = argv[optind - 1];
 451             size_t arg_len = strlen (arg);
 452             size_t mode_comma_len = mode_len + !!mode_len;
 453             size_t new_mode_len = mode_comma_len + arg_len;
 454             if (mode_alloc <= new_mode_len)
 455               {
 456                 mode_alloc = new_mode_len + 1;
 457                 mode = X2REALLOC (mode, &mode_alloc);
 458               }
 459             mode[mode_len] = ',';
 460             strcpy (mode + mode_comma_len, arg);
 461             mode_len = new_mode_len;
 462
 463             diagnose_surprises = true;
 464           }
 465           break;
 466         case NO_PRESERVE_ROOT:
 467           preserve_root = false;
 468           break;
 469         case PRESERVE_ROOT:
 470           preserve_root = true;
 471           break;
 472         case REFERENCE_FILE_OPTION:
 473           reference_file = optarg;
 474           break;
 475         case 'R':
 476           recurse = true;
 477           break;
 478         case 'c':
 479           verbosity = V_changes_only;
 480           break;
 481         case 'f':
 482           force_silent = true;
 483           break;
 484         case 'v':
 485           verbosity = V_high;
 486           break;
 487         case_GETOPT_HELP_CHAR;
 488         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 489         default:
 490           usage (EXIT_FAILURE);
 491         }
 492     }
 493
 494   if (reference_file)
 495     {
 496       if (mode)
 497         {
 498           error (0, 0, _("cannot combine mode and --reference options"));
 499           usage (EXIT_FAILURE);
 500         }
 501     }
 502   else
 503     {
 504       if (!mode)
 505         mode = argv[optind++];
 506     }
 507
 508   if (optind >= argc)
 509     {
 510       if (!mode || mode != argv[optind - 1])
 511         error (0, 0, _("missing operand"));
 512       else
 513         error (0, 0, _("missing operand after %s"), quote (argv[argc - 1]));
 514       usage (EXIT_FAILURE);
 515     }
 516
 517   if (reference_file)
 518     {
 519       change = mode_create_from_ref (reference_file);
 520       if (!change)
 521         error (EXIT_FAILURE, errno, _("failed to get attributes of %s"),
 522                quote (reference_file));
 523     }
 524   else
 525     {
 526       change = mode_compile (mode);
 527       if (!change)
 528         {
 529           error (0, 0, _("invalid mode: %s"), quote (mode));
 530           usage (EXIT_FAILURE);
 531         }
 532       umask_value = umask (0);
 533     }
 534
 535   if (recurse && preserve_root)
 536     {
 537       static struct dev_ino dev_ino_buf;
 538       root_dev_ino = get_root_dev_ino (&dev_ino_buf);
 539       if (root_dev_ino == NULL)
 540         error (EXIT_FAILURE, errno, _("failed to get attributes of %s"),
 541                quote ("/"));
 542     }
 543   else
 544     {
 545       root_dev_ino = NULL;
 546     }
 547
 548   ok = process_files (argv + optind,
 549                       FTS_COMFOLLOW | FTS_PHYSICAL | FTS_DEFER_STAT);
 550
 551   exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
 552 }