chmod.c

Linux下文件工具。

/* chmod -- change permission modes of files
   Copyright (C) 89, 90, 91, 1995-2001 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 2, 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, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* Written by David MacKenzie <[e-mail]> */

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

#include "system.h"
#include "error.h"
#include "filemode.h"
#include "modechange.h"
#include "quote.h"
#include "savedir.h"

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

#define AUTHORS "David MacKenzie"

enum Change_status
{
  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
};

static int change_dir_mode PARAMS ((const char *dir,
				    const struct mode_change *changes));

/* The name the program was run with. */
char *program_name;

/* If nonzero, change the modes of directories recursively. */
static int recurse;

/* If nonzero, force silence (no error messages). */
static int force_silent;

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

/* The argument to the --reference option.  Use the owner and group IDs
   of this file.  This file must exist.  */
static char *reference_file;

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

static struct option const long_options[] =
{
  {"recursive", no_argument, 0, 'R'},
  {"changes", no_argument, 0, 'c'},
  {"silent", no_argument, 0, 'f'},
  {"quiet", no_argument, 0, 'f'},
  {"reference", required_argument, 0, REFERENCE_FILE_OPTION},
  {"verbose", no_argument, 0, 'v'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {0, 0, 0, 0}
};

static int
mode_changed (const char *file, mode_t old_mode)
{
  struct stat new_stats;

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

  return old_mode != new_stats.st_mode;
}

/* 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[11];		/* "-rwxrwxrwx" ls-style modes. */
  const char *fmt;

  mode_string (mode, perms);
  perms[10] = '\0';		/* `mode_string' does not null terminate. */
  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) (mode & CHMOD_MODE_BITS), &perms[1]);
}

/* Change the mode of FILE according to the list of operations CHANGES.
   If DEREF_SYMLINK is nonzero and FILE is a symbolic link, change the
   mode of the referenced file.  If DEREF_SYMLINK is zero, ignore symbolic
   links.  Return 0 if successful, 1 if errors occurred. */

static int
change_file_mode (const char *file, const struct mode_change *changes,
		  const int deref_symlink)
{
  struct stat file_stats;
  mode_t newmode;
  int errors = 0;
  int fail;
  int saved_errno;

  if (deref_symlink ? stat (file, &file_stats) : lstat (file, &file_stats))
    {
      if (force_silent == 0)
	error (0, errno, _("failed to get attributes of %s"), quote (file));
      return 1;
    }

#ifdef S_ISLNK
  if (S_ISLNK (file_stats.st_mode))
    return 0;
#endif

  newmode = mode_adjust (file_stats.st_mode, changes);

  fail = chmod (file, newmode);
  saved_errno = errno;

  if (verbosity == V_high
      || (verbosity == V_changes_only
	  && !fail && mode_changed (file, file_stats.st_mode)))
    describe_change (file, newmode, (fail ? CH_FAILED : CH_SUCCEEDED));

  if (fail)
    {
      if (force_silent == 0)
	error (0, saved_errno, _("changing permissions of %s"),
	       quote (file));
      errors = 1;
    }

  if (recurse && S_ISDIR (file_stats.st_mode))
    errors |= change_dir_mode (file, changes);
  return errors;
}

/* Recursively change the modes of the files in directory DIR
   according to the list of operations CHANGES.
   Return 0 if successful, 1 if errors occurred. */

static int
change_dir_mode (const char *dir, const struct mode_change *changes)
{
  char *name_space, *namep;
  char *path;			/* Full path of each entry to process. */
  unsigned dirlength;		/* Length of DIR and '\0'. */
  unsigned filelength;		/* Length of each pathname to process. */
  unsigned pathlength;		/* Bytes allocated for `path'. */
  int errors = 0;

  name_space = savedir (dir);
  if (name_space == NULL)
    {
      if (force_silent == 0)
	error (0, errno, "%s", quote (dir));
      return 1;
    }

  dirlength = strlen (dir) + 1;	/* + 1 is for the trailing '/'. */
  pathlength = dirlength + 1;
  /* Give `path' a dummy value; it will be reallocated before first use. */
  path = xmalloc (pathlength);
  strcpy (path, dir);
  path[dirlength - 1] = '/';

  for (namep = name_space; *namep; namep += filelength - dirlength)
    {
      filelength = dirlength + strlen (namep) + 1;
      if (filelength > pathlength)
	{
	  pathlength = filelength * 2;
	  path = xrealloc (path, pathlength);
	}
      strcpy (path + dirlength, namep);
      errors |= change_file_mode (path, changes, 0);
    }
  free (path);
  free (name_space);
  return errors;
}

void
usage (int status)
{
  if (status != 0)
    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\
  -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 one or more of the letters ugoa, one of the symbols +-= and\n\
one or more of the letters rwxXstugo.\n\
"), stdout);
      printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
    }
  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)
{
  struct mode_change *changes;
  int errors = 0;
  int modeind = 0;		/* Index of the mode argument in `argv'. */
  int thisind;
  int c;

  program_name = argv[0];
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  recurse = force_silent = 0;

  while (1)
    {
      thisind = optind ? optind : 1;

      c = getopt_long (argc, argv, "RcfvrwxXstugoa,+-=", long_options, NULL);
      if (c == -1)
	break;

      switch (c)
	{
	case 0:
	  break;
	case 'r':
	case 'w':
	case 'x':
	case 'X':
	case 's':
	case 't':
	case 'u':
	case 'g':
	case 'o':
	case 'a':
	case ',':
	case '+':
	case '-':
	case '=':
	  if (modeind != 0 && modeind != thisind)
	    {
	      static char char_string[2] = {0, 0};
	      char_string[0] = c;
	      error (1, 0, _("invalid character %s in mode string %s"),
		     quote_n (0, char_string), quote_n (1, argv[thisind]));
	    }
	  modeind = thisind;
	  break;
	case REFERENCE_FILE_OPTION:
	  reference_file = optarg;
	  break;
	case 'R':
	  recurse = 1;
	  break;
	case 'c':
	  verbosity = V_changes_only;
	  break;
	case 'f':
	  force_silent = 1;
	  break;
	case 'v':
	  verbosity = V_high;
	  break;
	case_GETOPT_HELP_CHAR;
	case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
	default:
	  usage (1);
	}
    }

  if (modeind == 0 && reference_file == NULL)
    modeind = optind++;

  if (optind >= argc)
    {
      error (0, 0, _("too few arguments"));
      usage (1);
    }

  changes = (reference_file ? mode_create_from_ref (reference_file)
	     : mode_compile (argv[modeind], MODE_MASK_ALL));

  if (changes == MODE_INVALID)
    error (1, 0, _("invalid mode string: %s"), quote (argv[modeind]));
  else if (changes == MODE_MEMORY_EXHAUSTED)
    xalloc_die ();
  else if (changes == MODE_BAD_REFERENCE)
    error (1, errno, _("failed to get attributes of %s"),
	   quote (reference_file));

  for (; optind < argc; ++optind)
    errors |= change_file_mode (argv[optind], changes, 1);

  exit (errors);
}