path: root/src/chmod.c

/* chmod -- change permission modes of files
   Copyright (C) 89, 90, 91, 1995-2009 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Written by David MacKenzie <djm@gnu.ai.mit.edu> */

#include <config.h>
#include <stdio.h>
#include <getopt.h>
#include <sys/types.h>

#include "system.h"
#include "dev-ino.h"
#include "error.h"
#include "filemode.h"
#include "modechange.h"
#include "quote.h"
#include "quotearg.h"
#include "root-dev-ino.h"
#include "xfts.h"

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "chmod"

#define AUTHORS \
  proper_name ("David MacKenzie"), \
  proper_name ("Jim Meyering")

enum Change_status
{
  CH_NOT_APPLIED,
  CH_SUCCEEDED,
  CH_FAILED,
  CH_NO_CHANGE_REQUESTED
};

enum Verbosity
{
  /* Print a message for each file that is processed.  */
  V_high,

  /* Print a message for each file whose attributes we change.  */
  V_changes_only,

  /* Do not be verbose.  This is the default. */
  V_off
};

/* The desired change to the mode.  */
static struct mode_change *change;

/* The initial umask value, if it might be needed.  */
static mode_t umask_value;

/* If true, change the modes of directories recursively. */
static bool recurse;

/* If true, force silence (suppress most of error messages). */
static bool force_silent;

/* If true, diagnose surprises from naive misuses like "chmod -r file".
   POSIX allows diagnostics here, as portable code is supposed to use
   "chmod -- -r file".  */
static bool diagnose_surprises;

/* Level of verbosity.  */
static enum Verbosity verbosity = V_off;

/* Pointer to the device and inode numbers of `/', when --recursive.
   Otherwise NULL.  */
static struct dev_ino *root_dev_ino;

/* For long options that have no equivalent short option, use a
   non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
enum
{
  NO_PRESERVE_ROOT = CHAR_MAX + 1,
  PRESERVE_ROOT,
  REFERENCE_FILE_OPTION
};

static struct option const long_options[] =
{
  {"changes", no_argument, NULL, 'c'},
  {"recursive", no_argument, NULL, 'R'},
  {"no-preserve-root", no_argument, NULL, NO_PRESERVE_ROOT},
  {"preserve-root", no_argument, NULL, PRESERVE_ROOT},
  {"quiet", no_argument, NULL, 'f'},
  {"reference", required_argument, NULL, REFERENCE_FILE_OPTION},
  {"silent", no_argument, NULL, 'f'},
  {"verbose", no_argument, NULL, 'v'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

/* Return true if the chmodable permission bits of FILE changed.
   The old mode was OLD_MODE, but it was changed to NEW_MODE.  */

static bool
mode_changed (char const *file, mode_t old_mode, mode_t new_mode)
{
  if (new_mode & (S_ISUID | S_ISGID | S_ISVTX))
    {
      /* The new mode contains unusual bits that the call to chmod may
	 have silently cleared.  Check whether they actually changed.  */

      struct stat new_stats;

      if (stat (file, &new_stats) != 0)
	{
	  if (! force_silent)
	    error (0, errno, _("getting new attributes of %s"), quote (file));
	  return false;
	}

      new_mode = new_stats.st_mode;
    }

  return ((old_mode ^ new_mode) & CHMOD_MODE_BITS) != 0;
}

/* Tell the user how/if the MODE of FILE has been changed.
   CHANGED describes what (if anything) has happened. */

static void
describe_change (const char *file, mode_t mode,
		 enum Change_status changed)
{
  char perms[12];		/* "-rwxrwxrwx" ls-style modes. */
  const char *fmt;

  if (changed == CH_NOT_APPLIED)
    {
      printf (_("neither symbolic link %s nor referent has been changed\n"),
	      quote (file));
      return;
    }

  strmode (mode, perms);
  perms[10] = '\0';		/* Remove trailing space.  */
  switch (changed)
    {
    case CH_SUCCEEDED:
      fmt = _("mode of %s changed to %04lo (%s)\n");
      break;
    case CH_FAILED:
      fmt = _("failed to change mode of %s to %04lo (%s)\n");
      break;
    case CH_NO_CHANGE_REQUESTED:
      fmt = _("mode of %s retained as %04lo (%s)\n");
      break;
    default:
      abort ();
    }
  printf (fmt, quote (file),
	  (unsigned long int) (mode & CHMOD_MODE_BITS), &perms[1]);
}

/* Change the mode of FILE.
   Return true if successful.  This function is called
   once for every file system object that fts encounters.  */

static bool
process_file (FTS *fts, FTSENT *ent)
{
  char const *file_full_name = ent->fts_path;
  char const *file = ent->fts_accpath;
  const struct stat *file_stats = ent->fts_statp;
  mode_t old_mode IF_LINT (= 0);
  mode_t new_mode IF_LINT (= 0);
  bool ok = true;
  bool chmod_succeeded = false;

  switch (ent->fts_info)
    {
    case FTS_DP:
      return true;

    case FTS_NS:
      /* For a top-level file or directory, this FTS_NS (stat failed)
	 indicator is determined at the time of the initial fts_open call.
	 With programs like chmod, chown, and chgrp, that modify
	 permissions, it is possible that the file in question is
	 accessible when control reaches this point.  So, if this is
	 the first time we've seen the FTS_NS for this file, tell
	 fts_read to stat it "again".  */
      if (ent->fts_level == 0 && ent->fts_number == 0)
	{
	  ent->fts_number = 1;
	  fts_set (fts, ent, FTS_AGAIN);
	  return true;
	}
      if (! force_silent)
        error (0, ent->fts_errno, _("cannot access %s"),
	       quote (file_full_name));
      ok = false;
      break;

    case FTS_ERR:
      if (! force_silent)
        error (0, ent->fts_errno, _("%s"), quote (file_full_name));
      ok = false;
      break;

    case FTS_DNR:
      if (! force_silent)
        error (0, ent->fts_errno, _("cannot read directory %s"),
	       quote (file_full_name));
      ok = false;
      break;

    case FTS_SLNONE:
      if (! force_silent)
        error (0, 0, _("cannot operate on dangling symlink %s"),
	       quote (file_full_name));
      ok = false;

    default:
      break;
    }

  if (ok && ROOT_DEV_INO_CHECK (root_dev_ino, file_stats))
    {
      ROOT_DEV_INO_WARN (file_full_name);
      /* Tell fts not to traverse into this hierarchy.  */
      fts_set (fts, ent, FTS_SKIP);
      /* Ensure that we do not process "/" on the second visit.  */
      ent = fts_read (fts);
      ok = false;
    }

  if (ok)
    {
      old_mode = file_stats->st_mode;
      new_mode = mode_adjust (old_mode, S_ISDIR (old_mode) != 0, umask_value,
			      change, NULL);

      if (! S_ISLNK (old_mode))
	{
	  if (chmodat (fts->fts_cwd_fd, file, new_mode) == 0)
	    chmod_succeeded = true;
	  else
	    {
	      if (! force_silent)
		error (0, errno, _("changing permissions of %s"),
		       quote (file_full_name));
	      ok = false;
	    }
	}
    }

  if (verbosity != V_off)
    {
      bool changed = (chmod_succeeded
		      && mode_changed (file, old_mode, new_mode));

      if (changed || verbosity == V_high)
	{
	  enum Change_status ch_status =
	    (!ok ? CH_FAILED
	     : !chmod_succeeded ? CH_NOT_APPLIED
	     : !changed ? CH_NO_CHANGE_REQUESTED
	     : CH_SUCCEEDED);
	  describe_change (file_full_name, new_mode, ch_status);
	}
    }

  if (chmod_succeeded & diagnose_surprises)
    {
      mode_t naively_expected_mode =
	mode_adjust (old_mode, S_ISDIR (old_mode) != 0, 0, change, NULL);
      if (new_mode & ~naively_expected_mode)
	{
	  char new_perms[12];
	  char naively_expected_perms[12];
	  strmode (new_mode, new_perms);
	  strmode (naively_expected_mode, naively_expected_perms);
	  new_perms[10] = naively_expected_perms[10] = '\0';
	  error (0, 0,
		 _("%s: new permissions are %s, not %s"),
		 quotearg_colon (file_full_name),
		 new_perms + 1, naively_expected_perms + 1);
	  ok = false;
	}
    }

  if ( ! recurse)
    fts_set (fts, ent, FTS_SKIP);

  return ok;
}

/* Recursively change the modes of the specified FILES (the last entry
   of which is NULL).  BIT_FLAGS controls how fts works.
   Return true if successful.  */

static bool
process_files (char **files, int bit_flags)
{
  bool ok = true;

  FTS *fts = xfts_open (files, bit_flags, NULL);

  while (1)
    {
      FTSENT *ent;

      ent = fts_read (fts);
      if (ent == NULL)
	{
	  if (errno != 0)
	    {
	      /* FIXME: try to give a better message  */
	      if (! force_silent)
	        error (0, errno, _("fts_read failed"));
	      ok = false;
	    }
	  break;
	}

      ok &= process_file (fts, ent);
    }

  /* Ignore failure, since the only way it can do so is in failing to
     return to the original directory, and since we're about to exit,
     that doesn't matter.  */
  fts_close (fts);

  return ok;
}

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
	     program_name);
  else
    {
      printf (_("\
Usage: %s [OPTION]... MODE[,MODE]... FILE...\n\
  or:  %s [OPTION]... OCTAL-MODE FILE...\n\
  or:  %s [OPTION]... --reference=RFILE FILE...\n\
"),
	      program_name, program_name, program_name);
      fputs (_("\
Change the mode of each FILE to MODE.\n\
\n\
  -c, --changes           like verbose but report only when a change is made\n\
"), stdout);
      fputs (_("\
      --no-preserve-root  do not treat `/' specially (the default)\n\
      --preserve-root     fail to operate recursively on `/'\n\
"), stdout);
      fputs (_("\
  -f, --silent, --quiet   suppress most error messages\n\
  -v, --verbose           output a diagnostic for every file processed\n\
      --reference=RFILE   use RFILE's mode instead of MODE values\n\
  -R, --recursive         change files and directories recursively\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      fputs (_("\
\n\
Each MODE is of the form `[ugoa]*([-+=]([rwxXst]*|[ugo]))+'.\n\
"), stdout);
      emit_bug_reporting_address ();
    }
  exit (status);
}

/* Parse the ASCII mode given on the command line into a linked list
   of `struct mode_change' and apply that to each file argument. */

int
main (int argc, char **argv)
{
  char *mode = NULL;
  size_t mode_len = 0;
  size_t mode_alloc = 0;
  bool ok;
  bool preserve_root = false;
  char const *reference_file = NULL;
  int c;

  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  recurse = force_silent = diagnose_surprises = false;

  while ((c = getopt_long (argc, argv,
			   "Rcfvr::w::x::X::s::t::u::g::o::a::,::+::=::",
			   long_options, NULL))
	 != -1)
    {
      switch (c)
	{
	case 'r':
	case 'w':
	case 'x':
	case 'X':
	case 's':
	case 't':
	case 'u':
	case 'g':
	case 'o':
	case 'a':
	case ',':
	case '+':
	case '=':
	  /* Support nonportable uses like "chmod -w", but diagnose
	     surprises due to umask confusion.  Even though "--", "--r",
	     etc., are valid modes, there is no "case '-'" here since
	     getopt_long reserves leading "--" for long options.  */
	  {
	    /* Allocate a mode string (e.g., "-rwx") by concatenating
	       the argument containing this option.  If a previous mode
	       string was given, concatenate the previous string, a
	       comma, and the new string (e.g., "-s,-rwx").  */

	    char const *arg = argv[optind - 1];
	    size_t arg_len = strlen (arg);
	    size_t mode_comma_len = mode_len + !!mode_len;
	    size_t new_mode_len = mode_comma_len + arg_len;
	    if (mode_alloc <= new_mode_len)
	      {
		mode_alloc = new_mode_len + 1;
		mode = X2REALLOC (mode, &mode_alloc);
	      }
	    mode[mode_len] = ',';
	    strcpy (mode + mode_comma_len, arg);
	    mode_len = new_mode_len;

	    diagnose_surprises = true;
	  }
	  break;
	case NO_PRESERVE_ROOT:
	  preserve_root = false;
	  break;
	case PRESERVE_ROOT:
	  preserve_root = true;
	  break;
	case REFERENCE_FILE_OPTION:
	  reference_file = optarg;
	  break;
	case 'R':
	  recurse = true;
	  break;
	case 'c':
	  verbosity = V_changes_only;
	  break;
	case 'f':
	  force_silent = true;
	  break;
	case 'v':
	  verbosity = V_high;
	  break;
	case_GETOPT_HELP_CHAR;
	case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
	default:
	  usage (EXIT_FAILURE);
	}
    }

  if (reference_file)
    {
      if (mode)
	{
	  error (0, 0, _("cannot combine mode and --reference options"));
	  usage (EXIT_FAILURE);
	}
    }
  else
    {
      if (!mode)
	mode = argv[optind++];
    }

  if (optind >= argc)
    {
      if (!mode || mode != argv[optind - 1])
	error (0, 0, _("missing operand"));
      else
	error (0, 0, _("missing operand after %s"), quote (argv[argc - 1]));
      usage (EXIT_FAILURE);
    }

  if (reference_file)
    {
      change = mode_create_from_ref (reference_file);
      if (!change)
	error (EXIT_FAILURE, errno, _("failed to get attributes of %s"),
	       quote (reference_file));
    }
  else
    {
      change = mode_compile (mode);
      if (!change)
	{
	  error (0, 0, _("invalid mode: %s"), quote (mode));
	  usage (EXIT_FAILURE);
	}
      umask_value = umask (0);
    }

  if (recurse & preserve_root)
    {
      static struct dev_ino dev_ino_buf;
      root_dev_ino = get_root_dev_ino (&dev_ino_buf);
      if (root_dev_ino == NULL)
	error (EXIT_FAILURE, errno, _("failed to get attributes of %s"),
	       quote ("/"));
    }
  else
    {
      root_dev_ino = NULL;
    }

  ok = process_files (argv + optind,
		      FTS_COMFOLLOW | FTS_PHYSICAL | FTS_DEFER_STAT);

  exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
}