diff.c

制作2.6内核的CLFS时 使用的diffutils-2.8.7.tar.gz包

    %%  %\n\
    %c'C'  the single character C\n\
    %c'\\OOO'  the character with octal code OOO"),
  "",
  N_("-l  --paginate  Pass the output through `pr' to paginate it."),
  N_("-t  --expand-tabs  Expand tabs to spaces in output."),
  N_("-T  --initial-tab  Make tabs line up by prepending a tab."),
  N_("--tabsize=NUM  Tab stops are every NUM (default 8) print columns."),
  "",
  N_("-r  --recursive  Recursively compare any subdirectories found."),
  N_("-N  --new-file  Treat absent files as empty."),
  N_("--unidirectional-new-file  Treat absent first files as empty."),
  N_("-s  --report-identical-files  Report when two files are the same."),
  N_("-x PAT  --exclude=PAT  Exclude files that match PAT."),
  N_("-X FILE  --exclude-from=FILE  Exclude files that match any pattern in FILE."),
  N_("-S FILE  --starting-file=FILE  Start with FILE when comparing directories."),
  N_("--from-file=FILE1  Compare FILE1 to all operands.  FILE1 can be a directory."),
  N_("--to-file=FILE2  Compare all operands to FILE2.  FILE2 can be a directory."),
  "",
  N_("--horizon-lines=NUM  Keep NUM lines of the common prefix and suffix."),
  N_("-d  --minimal  Try hard to find a smaller set of changes."),
  N_("--speed-large-files  Assume large files and many scattered small changes."),
  "",
  N_("-v  --version  Output version info."),
  N_("--help  Output this help."),
  "",
  N_("FILES are `FILE1 FILE2' or `DIR1 DIR2' or `DIR FILE...' or `FILE... DIR'."),
  N_("If --from-file or --to-file is given, there are no restrictions on FILES."),
  N_("If a FILE is `-', read standard input."),
  N_("Exit status is 0 if inputs are the same, 1 if different, 2 if trouble."),
  "",
  N_("Report bugs to <[e-mail]>."),
  0
};

static void
usage (void)
{
  char const * const *p;

  printf (_("Usage: %s [OPTION]... FILES\n"), program_name);

  for (p = option_help_msgid;  *p;  p++)
    {
      if (!**p)
	putchar ('\n');
      else
	{
	  char const *msg = _(*p);
	  char const *nl;
	  while ((nl = strchr (msg, '\n')))
	    {
	      int msglen = nl + 1 - msg;
	      printf ("  %.*s", msglen, msg);
	      msg = nl + 1;
	    }

	  printf ("  %s\n" + 2 * (*msg != ' ' && *msg != '-'), msg);
	}
    }
}

/* Set VAR to VALUE, reporting an OPTION error if this is a
   conflict.  */
static void
specify_value (char const **var, char const *value, char const *option)
{
  if (*var && strcmp (*var, value) != 0)
    {
      error (0, 0, _("conflicting %s option value `%s'"), option, value);
      try_help (0, 0);
    }
  *var = value;
}

/* Set the output style to STYLE, diagnosing conflicts.  */
static void
specify_style (enum output_style style)
{
  if (output_style != style)
    {
      if (output_style != OUTPUT_UNSPECIFIED)
	try_help ("conflicting output style options", 0);
      output_style = style;
    }
}

/* Set the last-modified time of *ST to be the current time.  */

static void
set_mtime_to_now (struct stat *st)
{
#ifdef ST_MTIM_NSEC

# if HAVE_CLOCK_GETTIME && defined CLOCK_REALTIME
  if (clock_gettime (CLOCK_REALTIME, &st->st_mtim) == 0)
    return;
# endif

# if HAVE_GETTIMEOFDAY
  {
    struct timeval timeval;
    if (gettimeofday (&timeval, 0) == 0)
      {
	st->st_mtime = timeval.tv_sec;
	st->st_mtim.ST_MTIM_NSEC = timeval.tv_usec * 1000;
	return;
      }
  }
# endif

#endif /* ST_MTIM_NSEC */

  time (&st->st_mtime);
}

/* Compare two files (or dirs) with parent comparison PARENT
   and names NAME0 and NAME1.
   (If PARENT is 0, then the first name is just NAME0, etc.)
   This is self-contained; it opens the files and closes them.

   Value is EXIT_SUCCESS if files are the same, EXIT_FAILURE if
   different, EXIT_TROUBLE if there is a problem opening them.  */

static int
compare_files (struct comparison const *parent,
	       char const *name0,
	       char const *name1)
{
  struct comparison cmp;
#define DIR_P(f) (S_ISDIR (cmp.file[f].stat.st_mode) != 0)
  register int f;
  int status = EXIT_SUCCESS;
  bool same_files;
  char *free0, *free1;

  /* If this is directory comparison, perhaps we have a file
     that exists only in one of the directories.
     If so, just print a message to that effect.  */

  if (! ((name0 && name1)
	 || (unidirectional_new_file && name1)
	 || new_file))
    {
      char const *name = name0 == 0 ? name1 : name0;
      char const *dir = parent->file[name0 == 0].name;

      /* See POSIX 1003.1-2001 for this format.  */
      message ("Only in %s: %s\n", dir, name);

      /* Return EXIT_FAILURE so that diff_dirs will return
	 EXIT_FAILURE ("some files differ").  */
      return EXIT_FAILURE;
    }

  memset (cmp.file, 0, sizeof cmp.file);
  cmp.parent = parent;

  /* cmp.file[f].desc markers */
#define NONEXISTENT (-1) /* nonexistent file */
#define UNOPENED (-2) /* unopened file (e.g. directory) */
#define ERRNO_ENCODE(errno) (-3 - (errno)) /* encoded errno value */

#define ERRNO_DECODE(desc) (-3 - (desc)) /* inverse of ERRNO_ENCODE */

  cmp.file[0].desc = name0 == 0 ? NONEXISTENT : UNOPENED;
  cmp.file[1].desc = name1 == 0 ? NONEXISTENT : UNOPENED;

  /* Now record the full name of each file, including nonexistent ones.  */

  if (name0 == 0)
    name0 = name1;
  if (name1 == 0)
    name1 = name0;

  if (!parent)
    {
      free0 = 0;
      free1 = 0;
      cmp.file[0].name = name0;
      cmp.file[1].name = name1;
    }
  else
    {
      cmp.file[0].name = free0
	= dir_file_pathname (parent->file[0].name, name0);
      cmp.file[1].name = free1
	= dir_file_pathname (parent->file[1].name, name1);
    }

  /* Stat the files.  */

  for (f = 0; f < 2; f++)
    {
      if (cmp.file[f].desc != NONEXISTENT)
	{
	  if (f && file_name_cmp (cmp.file[f].name, cmp.file[0].name) == 0)
	    {
	      cmp.file[f].desc = cmp.file[0].desc;
	      cmp.file[f].stat = cmp.file[0].stat;
	    }
	  else if (strcmp (cmp.file[f].name, "-") == 0)
	    {
	      cmp.file[f].desc = STDIN_FILENO;
	      if (fstat (STDIN_FILENO, &cmp.file[f].stat) != 0)
		cmp.file[f].desc = ERRNO_ENCODE (errno);
	      else
		{
		  if (S_ISREG (cmp.file[f].stat.st_mode))
		    {
		      off_t pos = lseek (STDIN_FILENO, (off_t) 0, SEEK_CUR);
		      if (pos < 0)
			cmp.file[f].desc = ERRNO_ENCODE (errno);
		      else
			cmp.file[f].stat.st_size =
			  MAX (0, cmp.file[f].stat.st_size - pos);
		    }

		  /* POSIX 1003.1-2001 requires current time for
		     stdin.  */
		  set_mtime_to_now (&cmp.file[f].stat);
		}
	    }
	  else if (stat (cmp.file[f].name, &cmp.file[f].stat) != 0)
	    cmp.file[f].desc = ERRNO_ENCODE (errno);
	}
    }

  /* Mark files as nonexistent as needed for -N and -P, if they are
     inaccessible empty regular files (the kind of files that 'patch'
     creates to indicate nonexistent backups), or if they are
     top-level files that do not exist but their counterparts do
     exist.  */
  for (f = 0; f < 2; f++)
    if ((new_file || (f == 0 && unidirectional_new_file))
	&& (cmp.file[f].desc == UNOPENED
	    ? (S_ISREG (cmp.file[f].stat.st_mode)
	       && ! (cmp.file[f].stat.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO))
	       && cmp.file[f].stat.st_size == 0)
	    : (cmp.file[f].desc == ERRNO_ENCODE (ENOENT)
	       && ! parent
	       && cmp.file[1 - f].desc == UNOPENED)))
      cmp.file[f].desc = NONEXISTENT;

  for (f = 0; f < 2; f++)
    if (cmp.file[f].desc == NONEXISTENT)
      {
	memset (&cmp.file[f].stat, 0, sizeof cmp.file[f].stat);
	cmp.file[f].stat.st_mode = cmp.file[1 - f].stat.st_mode;
      }

  for (f = 0; f < 2; f++)
    {
      int e = ERRNO_DECODE (cmp.file[f].desc);
      if (0 <= e)
	{
	  errno = e;
	  perror_with_name (cmp.file[f].name);
	  status = EXIT_TROUBLE;
	}
    }

  if (status == EXIT_SUCCESS && ! parent && DIR_P (0) != DIR_P (1))
    {
      /* If one is a directory, and it was specified in the command line,
	 use the file in that dir with the other file's basename.  */

      int fnm_arg = DIR_P (0);
      int dir_arg = 1 - fnm_arg;
      char const *fnm = cmp.file[fnm_arg].name;
      char const *dir = cmp.file[dir_arg].name;
      char const *filename = cmp.file[dir_arg].name = free0
	= dir_file_pathname (dir, base_name (fnm));

      if (strcmp (fnm, "-") == 0)
	fatal ("cannot compare `-' to a directory");

      if (stat (filename, &cmp.file[dir_arg].stat) != 0)
	{
	  perror_with_name (filename);
	  status = EXIT_TROUBLE;
	}
    }

  if (status != EXIT_SUCCESS)
    {
      /* One of the files should exist but does not.  */
    }
  else if (cmp.file[0].desc == NONEXISTENT
	   && cmp.file[1].desc == NONEXISTENT)
    {
      /* Neither file "exists", so there's nothing to compare.  */
    }
  else if ((same_files
	    = (cmp.file[0].desc != NONEXISTENT
	       && cmp.file[1].desc != NONEXISTENT
	       && 0 < same_file (&cmp.file[0].stat, &cmp.file[1].stat)
	       && same_file_attributes (&cmp.file[0].stat,
					&cmp.file[1].stat)))
	   && no_diff_means_no_output)
    {
      /* The two named files are actually the same physical file.
	 We know they are identical without actually reading them.  */
    }
  else if (DIR_P (0) & DIR_P (1))
    {
      if (output_style == OUTPUT_IFDEF)
	fatal ("-D option not supported with directories");

      /* If both are directories, compare the files in them.  */

      if (parent && !recursive)
	{
	  /* But don't compare dir contents one level down
	     unless -r was specified.
	     See POSIX 1003.1-2001 for this format.  */
	  message ("Common subdirectories: %s and %s\n",
		   cmp.file[0].name, cmp.file[1].name);
	}
      else
	status = diff_dirs (&cmp, compare_files);
    }
  else if ((DIR_P (0) | DIR_P (1))
	   || (parent
	       && (! S_ISREG (cmp.file[0].stat.st_mode)
		   || ! S_ISREG (cmp.file[1].stat.st_mode))))
    {
      if (cmp.file[0].desc == NONEXISTENT || cmp.file[1].desc == NONEXISTENT)
	{
	  /* We have a subdirectory that exists only in one directory.  */

	  if ((DIR_P (0) | DIR_P (1))
	      && recursive
	      && (new_file
		  || (unidirectional_new_file
		      && cmp.file[0].desc == NONEXISTENT)))
	    status = diff_dirs (&cmp, compare_files);
	  else
	    {
	      char const *dir
		= parent->file[cmp.file[0].desc == NONEXISTENT].name;

	      /* See POSIX 1003.1-2001 for this format.  */
	      message ("Only in %s: %s\n", dir, name0);

	      status = EXIT_FAILURE;
	    }
	}
      else
	{
	  /* We have two files that are not to be compared.  */

	  /* See POSIX 1003.1-2001 for this format.  */
	  message5 ("File %s is a %s while file %s is a %s\n",
		    file_label[0] ? file_label[0] : cmp.file[0].name,
		    file_type (&cmp.file[0].stat),
		    file_label[1] ? file_label[1] : cmp.file[1].name,
		    file_type (&cmp.file[1].stat));

	  /* This is a difference.  */
	  status = EXIT_FAILURE;
	}
    }
  else if (files_can_be_treated_as_binary
	   && S_ISREG (cmp.file[0].stat.st_mode)
	   && S_ISREG (cmp.file[1].stat.st_mode)
	   && cmp.file[0].stat.st_size != cmp.file[1].stat.st_size)
    {
      message ("Files %s and %s differ\n",
	       file_label[0] ? file_label[0] : cmp.file[0].name,
	       file_label[1] ? file_label[1] : cmp.file[1].name);
      status = EXIT_FAILURE;
    }
  else
    {
      /* Both exist and neither is a directory.  */

      /* Open the files and record their descriptors.  */

      if (cmp.file[0].desc == UNOPENED)
	if ((cmp.file[0].desc = open (cmp.file[0].name, O_RDONLY, 0)) < 0)
	  {
	    perror_with_name (cmp.file[0].name);
	    status = EXIT_TROUBLE;
	  }
      if (cmp.file[1].desc == UNOPENED)
	{
	  if (same_files)
	    cmp.file[1].desc = cmp.file[0].desc;
	  else if ((cmp.file[1].desc = open (cmp.file[1].name, O_RDONLY, 0))
		   < 0)
	    {
	      perror_with_name (cmp.file[1].name);
	      status = EXIT_TROUBLE;
	    }
	}

#if HAVE_SETMODE_DOS
      if (binary)
	for (f = 0; f < 2; f++)
	  if (0 <= cmp.file[f].desc)
	    set_binary_mode (cmp.file[f].desc, true);
#endif

      /* Compare the files, if no error was found.  */

      if (status == EXIT_SUCCESS)
	status = diff_2_files (&cmp);

      /* Close the file descriptors.  */

      if (0 <= cmp.file[0].desc && close (cmp.file[0].desc) != 0)
	{
	  perror_with_name (cmp.file[0].name);
	  status = EXIT_TROUBLE;
	}
      if (0 <= cmp.file[1].desc && cmp.file[0].desc != cmp.file[1].desc
	  && close (cmp.file[1].desc) != 0)
	{
	  perror_with_name (cmp.file[1].name);
	  status = EXIT_TROUBLE;
	}
    }

  /* Now the comparison has been done, if no error prevented it,
     and STATUS is the value this function will return.  */

  if (status == EXIT_SUCCESS)
    {
      if (report_identical_files && !DIR_P (0))
	message ("Files %s and %s are identical\n",
		 file_label[0] ? file_label[0] : cmp.file[0].name,
		 file_label[1] ? file_label[1] : cmp.file[1].name);
    }
  else
    {
      /* Flush stdout so that the user sees differences immediately.
	 This can hurt performance, unfortunately.  */
      if (fflush (stdout) != 0)
	pfatal_with_name (_("standard output"));
    }

  if (free0)
    free (free0);
  if (free1)
    free (free1);

  return status;
}