Virgin import of diffutils 2.8.7.

1 files changed, 1353 insertions, 0 deletions

diff --git a/contrib/diff/src/diff.c b/contrib/diff/src/diff.c
new file mode 100644
index 0000000..a975107
--- /dev/null
+++ b/contrib/diff/src/diff.c
@@ -0,0 +1,1353 @@
+/* diff - compare files line by line
+
+   Copyright (C) 1988, 1989, 1992, 1993, 1994, 1996, 1998, 2001, 2002,
+   2004 Free Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   GNU DIFF 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.
+
+   GNU DIFF 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 GNU DIFF; see the file COPYING.
+   If not, write to the Free Software Foundation,
+   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#define GDIFF_MAIN
+#include "diff.h"
+#include "paths.h"
+#include <c-stack.h>
+#include <dirname.h>
+#include <error.h>
+#include <exclude.h>
+#include <exit.h>
+#include <exitfail.h>
+#include <file-type.h>
+#include <fnmatch.h>
+#include <getopt.h>
+#include <hard-locale.h>
+#include <posixver.h>
+#include <prepargs.h>
+#include <quotesys.h>
+#include <setmode.h>
+#include <version-etc.h>
+#include <xalloc.h>
+
+#ifndef GUTTER_WIDTH_MINIMUM
+# define GUTTER_WIDTH_MINIMUM 3
+#endif
+
+struct regexp_list
+{
+  char *regexps;	/* chars representing disjunction of the regexps */
+  size_t len;		/* chars used in `regexps' */
+  size_t size;		/* size malloc'ed for `regexps'; 0 if not malloc'ed */
+  bool multiple_regexps;/* Does `regexps' represent a disjunction?  */
+  struct re_pattern_buffer *buf;
+};
+
+static int compare_files (struct comparison const *, char const *, char const *);
+static void add_regexp (struct regexp_list *, char const *);
+static void summarize_regexp_list (struct regexp_list *);
+static void specify_style (enum output_style);
+static void specify_value (char const **, char const *, char const *);
+static void try_help (char const *, char const *) __attribute__((noreturn));
+static void check_stdout (void);
+static void usage (void);
+
+/* If comparing directories, compare their common subdirectories
+   recursively.  */
+static bool recursive;
+
+/* In context diffs, show previous lines that match these regexps.  */
+static struct regexp_list function_regexp_list;
+
+/* Ignore changes affecting only lines that match these regexps.  */
+static struct regexp_list ignore_regexp_list;
+
+#if HAVE_SETMODE_DOS
+/* Use binary I/O when reading and writing data (--binary).
+   On POSIX hosts, this has no effect.  */
+static bool binary;
+#else
+enum { binary = true };
+#endif
+
+/* When comparing directories, if a file appears only in one
+   directory, treat it as present but empty in the other (-N).
+   Then `patch' would create the file with appropriate contents.  */
+static bool new_file;
+
+/* When comparing directories, if a file appears only in the second
+   directory of the two, treat it as present but empty in the other
+   (--unidirectional-new-file).
+   Then `patch' would create the file with appropriate contents.  */
+static bool unidirectional_new_file;
+
+/* Report files compared that are the same (-s).
+   Normally nothing is output when that happens.  */
+static bool report_identical_files;
+
+
+/* Return a string containing the command options with which diff was invoked.
+   Spaces appear between what were separate ARGV-elements.
+   There is a space at the beginning but none at the end.
+   If there were no options, the result is an empty string.
+
+   Arguments: OPTIONVEC, a vector containing separate ARGV-elements, and COUNT,
+   the length of that vector.  */
+
+static char *
+option_list (char **optionvec, int count)
+{
+  int i;
+  size_t size = 1;
+  char *result;
+  char *p;
+
+  for (i = 0; i < count; i++)
+    size += 1 + quote_system_arg ((char *) 0, optionvec[i]);
+
+  p = result = xmalloc (size);
+
+  for (i = 0; i < count; i++)
+    {
+      *p++ = ' ';
+      p += quote_system_arg (p, optionvec[i]);
+    }
+
+  *p = 0;
+  return result;
+}
+
+
+/* Return an option value suitable for add_exclude.  */
+
+static int
+exclude_options (void)
+{
+  return EXCLUDE_WILDCARDS | (ignore_file_name_case ? FNM_CASEFOLD : 0);
+}
+
+static char const shortopts[] =
+"0123456789abBcC:dD:eEfF:hHiI:lL:nNpPqrsS:tTuU:vwW:x:X:y";
+
+/* Values for long options that do not have single-letter equivalents.  */
+enum
+{
+  BINARY_OPTION = CHAR_MAX + 1,
+  FROM_FILE_OPTION,
+  HELP_OPTION,
+  HORIZON_LINES_OPTION,
+  IGNORE_FILE_NAME_CASE_OPTION,
+  INHIBIT_HUNK_MERGE_OPTION,
+  LEFT_COLUMN_OPTION,
+  LINE_FORMAT_OPTION,
+  NO_IGNORE_FILE_NAME_CASE_OPTION,
+  NORMAL_OPTION,
+  SDIFF_MERGE_ASSIST_OPTION,
+  STRIP_TRAILING_CR_OPTION,
+  SUPPRESS_COMMON_LINES_OPTION,
+  TABSIZE_OPTION,
+  TO_FILE_OPTION,
+
+  /* These options must be in sequence.  */
+  UNCHANGED_LINE_FORMAT_OPTION,
+  OLD_LINE_FORMAT_OPTION,
+  NEW_LINE_FORMAT_OPTION,
+
+  /* These options must be in sequence.  */
+  UNCHANGED_GROUP_FORMAT_OPTION,
+  OLD_GROUP_FORMAT_OPTION,
+  NEW_GROUP_FORMAT_OPTION,
+  CHANGED_GROUP_FORMAT_OPTION
+};
+
+static char const group_format_option[][sizeof "--unchanged-group-format"] =
+  {
+    "--unchanged-group-format",
+    "--old-group-format",
+    "--new-group-format",
+    "--changed-group-format"
+  };
+
+static char const line_format_option[][sizeof "--unchanged-line-format"] =
+  {
+    "--unchanged-line-format",
+    "--old-line-format",
+    "--new-line-format"
+  };
+
+static struct option const longopts[] =
+{
+  {"binary", 0, 0, BINARY_OPTION},
+  {"brief", 0, 0, 'q'},
+  {"changed-group-format", 1, 0, CHANGED_GROUP_FORMAT_OPTION},
+  {"context", 2, 0, 'C'},
+  {"ed", 0, 0, 'e'},
+  {"exclude", 1, 0, 'x'},
+  {"exclude-from", 1, 0, 'X'},
+  {"expand-tabs", 0, 0, 't'},
+  {"forward-ed", 0, 0, 'f'},
+  {"from-file", 1, 0, FROM_FILE_OPTION},
+  {"help", 0, 0, HELP_OPTION},
+  {"horizon-lines", 1, 0, HORIZON_LINES_OPTION},
+  {"ifdef", 1, 0, 'D'},
+  {"ignore-all-space", 0, 0, 'w'},
+  {"ignore-blank-lines", 0, 0, 'B'},
+  {"ignore-case", 0, 0, 'i'},
+  {"ignore-file-name-case", 0, 0, IGNORE_FILE_NAME_CASE_OPTION},
+  {"ignore-matching-lines", 1, 0, 'I'},
+  {"ignore-space-change", 0, 0, 'b'},
+  {"ignore-tab-expansion", 0, 0, 'E'},
+  {"inhibit-hunk-merge", 0, 0, INHIBIT_HUNK_MERGE_OPTION},
+  {"initial-tab", 0, 0, 'T'},
+  {"label", 1, 0, 'L'},
+  {"left-column", 0, 0, LEFT_COLUMN_OPTION},
+  {"line-format", 1, 0, LINE_FORMAT_OPTION},
+  {"minimal", 0, 0, 'd'},
+  {"new-file", 0, 0, 'N'},
+  {"new-group-format", 1, 0, NEW_GROUP_FORMAT_OPTION},
+  {"new-line-format", 1, 0, NEW_LINE_FORMAT_OPTION},
+  {"no-ignore-file-name-case", 0, 0, NO_IGNORE_FILE_NAME_CASE_OPTION},
+  {"normal", 0, 0, NORMAL_OPTION},
+  {"old-group-format", 1, 0, OLD_GROUP_FORMAT_OPTION},
+  {"old-line-format", 1, 0, OLD_LINE_FORMAT_OPTION},
+  {"paginate", 0, 0, 'l'},
+  {"rcs", 0, 0, 'n'},
+  {"recursive", 0, 0, 'r'},
+  {"report-identical-files", 0, 0, 's'},
+  {"sdiff-merge-assist", 0, 0, SDIFF_MERGE_ASSIST_OPTION},
+  {"show-c-function", 0, 0, 'p'},
+  {"show-function-line", 1, 0, 'F'},
+  {"side-by-side", 0, 0, 'y'},
+  {"speed-large-files", 0, 0, 'H'},
+  {"starting-file", 1, 0, 'S'},
+  {"strip-trailing-cr", 0, 0, STRIP_TRAILING_CR_OPTION},
+  {"suppress-common-lines", 0, 0, SUPPRESS_COMMON_LINES_OPTION},
+  {"tabsize", 1, 0, TABSIZE_OPTION},
+  {"text", 0, 0, 'a'},
+  {"to-file", 1, 0, TO_FILE_OPTION},
+  {"unchanged-group-format", 1, 0, UNCHANGED_GROUP_FORMAT_OPTION},
+  {"unchanged-line-format", 1, 0, UNCHANGED_LINE_FORMAT_OPTION},
+  {"unidirectional-new-file", 0, 0, 'P'},
+  {"unified", 2, 0, 'U'},
+  {"version", 0, 0, 'v'},
+  {"width", 1, 0, 'W'},
+  {0, 0, 0, 0}
+};
+
+int
+main (int argc, char **argv)
+{
+  int exit_status = EXIT_SUCCESS;
+  int c;
+  int i;
+  int prev = -1;
+  lin ocontext = -1;
+  bool explicit_context = false;
+  size_t width = 0;
+  bool show_c_function = false;
+  char const *from_file = 0;
+  char const *to_file = 0;
+  uintmax_t numval;
+  char *numend;
+
+  /* Do our initializations.  */
+  exit_failure = 2;
+  initialize_main (&argc, &argv);
+  program_name = argv[0];
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+  c_stack_action (0);
+  function_regexp_list.buf = &function_regexp;
+  ignore_regexp_list.buf = &ignore_regexp;
+  re_set_syntax (RE_SYNTAX_GREP | RE_NO_POSIX_BACKTRACKING);
+  excluded = new_exclude ();
+
+  /* Decode the options.  */
+
+  while ((c = getopt_long (argc, argv, shortopts, longopts, 0)) != -1)
+    {
+      switch (c)
+	{
+	case 0:
+	  break;
+
+	case '0':
+	case '1':
+	case '2':
+	case '3':
+	case '4':
+	case '5':
+	case '6':
+	case '7':
+	case '8':
+	case '9':
+	  if (! ISDIGIT (prev))
+	    ocontext = c - '0';
+	  else if (LIN_MAX / 10 < ocontext
+		   || ((ocontext = 10 * ocontext + c - '0') < 0))
+	    ocontext = LIN_MAX;
+	  break;
+
+	case 'a':
+	  text = true;
+	  break;
+
+	case 'b':
+	  if (ignore_white_space < IGNORE_SPACE_CHANGE)
+	    ignore_white_space = IGNORE_SPACE_CHANGE;
+	  break;
+
+	case 'B':
+	  ignore_blank_lines = true;
+	  break;
+
+	case 'C':
+	case 'U':
+	  {
+	    if (optarg)
+	      {
+		numval = strtoumax (optarg, &numend, 10);
+		if (*numend)
+		  try_help ("invalid context length `%s'", optarg);
+		if (LIN_MAX < numval)
+		  numval = LIN_MAX;
+	      }
+	    else
+	      numval = 3;
+
+	    specify_style (c == 'U' ? OUTPUT_UNIFIED : OUTPUT_CONTEXT);
+	    if (context < numval)
+	      context = numval;
+	    explicit_context = true;
+	  }
+	  break;
+
+	case 'c':
+	  specify_style (OUTPUT_CONTEXT);
+	  if (context < 3)
+	    context = 3;
+	  break;
+
+	case 'd':
+	  minimal = true;
+	  break;
+
+	case 'D':
+	  specify_style (OUTPUT_IFDEF);
+	  {
+	    static char const C_ifdef_group_formats[] =
+	      "%%=%c#ifndef %s\n%%<#endif /* ! %s */\n%c#ifdef %s\n%%>#endif /* %s */\n%c#ifndef %s\n%%<#else /* %s */\n%%>#endif /* %s */\n";
+	    char *b = xmalloc (sizeof C_ifdef_group_formats
+			       + 7 * strlen (optarg) - 14 /* 7*"%s" */
+			       - 8 /* 5*"%%" + 3*"%c" */);
+	    sprintf (b, C_ifdef_group_formats,
+		     0,
+		     optarg, optarg, 0,
+		     optarg, optarg, 0,
+		     optarg, optarg, optarg);
+	    for (i = 0; i < sizeof group_format / sizeof *group_format; i++)
+	      {
+		specify_value (&group_format[i], b, "-D");
+		b += strlen (b) + 1;
+	      }
+	  }
+	  break;
+
+	case 'e':
+	  specify_style (OUTPUT_ED);
+	  break;
+
+	case 'E':
+	  if (ignore_white_space < IGNORE_TAB_EXPANSION)
+	    ignore_white_space = IGNORE_TAB_EXPANSION;
+	  break;
+
+	case 'f':
+	  specify_style (OUTPUT_FORWARD_ED);
+	  break;
+
+	case 'F':
+	  add_regexp (&function_regexp_list, optarg);
+	  break;
+
+	case 'h':
+	  /* Split the files into chunks for faster processing.
+	     Usually does not change the result.
+
+	     This currently has no effect.  */
+	  break;
+
+	case 'H':
+	  speed_large_files = true;
+	  break;
+
+	case 'i':
+	  ignore_case = true;
+	  break;
+
+	case 'I':
+	  add_regexp (&ignore_regexp_list, optarg);
+	  break;
+
+	case 'l':
+	  if (!pr_program[0])
+	    try_help ("pagination not supported on this host", 0);
+	  paginate = true;
+#ifdef SIGCHLD
+	  /* Pagination requires forking and waiting, and
+	     System V fork+wait does not work if SIGCHLD is ignored.  */
+	  signal (SIGCHLD, SIG_DFL);
+#endif
+	  break;
+
+	case 'L':
+	  if (!file_label[0])
+	    file_label[0] = optarg;
+	  else if (!file_label[1])
+	    file_label[1] = optarg;
+	  else
+	    fatal ("too many file label options");
+	  break;
+
+	case 'n':
+	  specify_style (OUTPUT_RCS);
+	  break;
+
+	case 'N':
+	  new_file = true;
+	  break;
+
+	case 'p':
+	  show_c_function = true;
+	  add_regexp (&function_regexp_list, "^[[:alpha:]$_]");
+	  break;
+
+	case 'P':
+	  unidirectional_new_file = true;
+	  break;
+
+	case 'q':
+	  brief = true;
+	  break;
+
+	case 'r':
+	  recursive = true;
+	  break;
+
+	case 's':
+	  report_identical_files = true;
+	  break;
+
+	case 'S':
+	  specify_value (&starting_file, optarg, "-S");
+	  break;
+
+	case 't':
+	  expand_tabs = true;
+	  break;
+
+	case 'T':
+	  initial_tab = true;
+	  break;
+
+	case 'u':
+	  specify_style (OUTPUT_UNIFIED);
+	  if (context < 3)
+	    context = 3;
+	  break;
+
+	case 'v':
+	  version_etc (stdout, "diff", PACKAGE_NAME, PACKAGE_VERSION,
+		       "Paul Eggert", "Mike Haertel", "David Hayes",
+		       "Richard Stallman", "Len Tower", (char *) 0);
+	  check_stdout ();
+	  return EXIT_SUCCESS;
+
+	case 'w':
+	  ignore_white_space = IGNORE_ALL_SPACE;
+	  break;
+
+	case 'x':
+	  add_exclude (excluded, optarg, exclude_options ());
+	  break;
+
+	case 'X':
+	  if (add_exclude_file (add_exclude, excluded, optarg,
+				exclude_options (), '\n'))
+	    pfatal_with_name (optarg);
+	  break;
+
+	case 'y':
+	  specify_style (OUTPUT_SDIFF);
+	  break;
+
+	case 'W':
+	  numval = strtoumax (optarg, &numend, 10);
+	  if (! (0 < numval && numval <= SIZE_MAX) || *numend)
+	    try_help ("invalid width `%s'", optarg);
+	  if (width != numval)
+	    {
+	      if (width)
+		fatal ("conflicting width options");
+	      width = numval;
+	    }
+	  break;
+
+	case BINARY_OPTION:
+#if HAVE_SETMODE_DOS
+	  binary = true;
+	  set_binary_mode (STDOUT_FILENO, true);
+#endif
+	  break;
+
+	case FROM_FILE_OPTION:
+	  specify_value (&from_file, optarg, "--from-file");
+	  break;
+
+	case HELP_OPTION:
+	  usage ();
+	  check_stdout ();
+	  return EXIT_SUCCESS;
+
+	case HORIZON_LINES_OPTION:
+	  numval = strtoumax (optarg, &numend, 10);
+	  if (*numend)
+	    try_help ("invalid horizon length `%s'", optarg);
+	  horizon_lines = MAX (horizon_lines, MIN (numval, LIN_MAX));
+	  break;
+
+	case IGNORE_FILE_NAME_CASE_OPTION:
+	  ignore_file_name_case = true;
+	  break;
+
+	case INHIBIT_HUNK_MERGE_OPTION:
+	  /* This option is obsolete, but accept it for backward
+             compatibility.  */
+	  break;
+
+	case LEFT_COLUMN_OPTION:
+	  left_column = true;
+	  break;
+
+	case LINE_FORMAT_OPTION:
+	  specify_style (OUTPUT_IFDEF);
+	  for (i = 0; i < sizeof line_format / sizeof *line_format; i++)
+	    specify_value (&line_format[i], optarg, "--line-format");
+	  break;
+
+	case NO_IGNORE_FILE_NAME_CASE_OPTION:
+	  ignore_file_name_case = false;
+	  break;
+
+	case NORMAL_OPTION:
+	  specify_style (OUTPUT_NORMAL);
+	  break;
+
+	case SDIFF_MERGE_ASSIST_OPTION:
+	  specify_style (OUTPUT_SDIFF);
+	  sdiff_merge_assist = true;
+	  break;
+
+	case STRIP_TRAILING_CR_OPTION:
+	  strip_trailing_cr = true;
+	  break;
+
+	case SUPPRESS_COMMON_LINES_OPTION:
+	  suppress_common_lines = true;
+	  break;
+
+	case TABSIZE_OPTION:
+	  numval = strtoumax (optarg, &numend, 10);
+	  if (! (0 < numval && numval <= SIZE_MAX) || *numend)
+	    try_help ("invalid tabsize `%s'", optarg);
+	  if (tabsize != numval)
+	    {
+	      if (tabsize)
+		fatal ("conflicting tabsize options");
+	      tabsize = numval;
+	    }
+	  break;
+
+	case TO_FILE_OPTION:
+	  specify_value (&to_file, optarg, "--to-file");
+	  break;
+
+	case UNCHANGED_LINE_FORMAT_OPTION:
+	case OLD_LINE_FORMAT_OPTION:
+	case NEW_LINE_FORMAT_OPTION:
+	  specify_style (OUTPUT_IFDEF);
+	  c -= UNCHANGED_LINE_FORMAT_OPTION;
+	  specify_value (&line_format[c], optarg, line_format_option[c]);
+	  break;
+
+	case UNCHANGED_GROUP_FORMAT_OPTION:
+	case OLD_GROUP_FORMAT_OPTION:
+	case NEW_GROUP_FORMAT_OPTION:
+	case CHANGED_GROUP_FORMAT_OPTION:
+	  specify_style (OUTPUT_IFDEF);
+	  c -= UNCHANGED_GROUP_FORMAT_OPTION;
+	  specify_value (&group_format[c], optarg, group_format_option[c]);
+	  break;
+
+	default:
+	  try_help (0, 0);
+	}
+      prev = c;
+    }
+
+  if (output_style == OUTPUT_UNSPECIFIED)
+    {
+      if (show_c_function)
+	{
+	  specify_style (OUTPUT_CONTEXT);
+	  if (ocontext < 0)
+	    context = 3;
+	}
+      else
+	specify_style (OUTPUT_NORMAL);
+    }
+
+  if (output_style != OUTPUT_CONTEXT || hard_locale (LC_TIME))
+    {
+#ifdef ST_MTIM_NSEC
+      time_format = "%Y-%m-%d %H:%M:%S.%N %z";
+#else
+      time_format = "%Y-%m-%d %H:%M:%S %z";
+#endif
+    }
+  else
+    {
+      /* See POSIX 1003.1-2001 for this format.  */
+      time_format = "%a %b %e %T %Y";
+    }
+
+  if (0 <= ocontext)
+    {
+      bool modern_usage = 200112 <= posix2_version ();
+
+      if ((output_style == OUTPUT_CONTEXT
+	   || output_style == OUTPUT_UNIFIED)
+	  && (context < ocontext
+	      || (ocontext < context && ! explicit_context)))
+	{
+	  if (modern_usage)
+	    {
+	      error (0, 0,
+		     _("`-%ld' option is obsolete; use `-%c %ld'"),
+		     (long int) ocontext,
+		     output_style == OUTPUT_CONTEXT ? 'C' : 'U',
+		     (long int) ocontext);
+	      try_help (0, 0);
+	    }
+	  context = ocontext;
+	}
+      else
+	{
+	  if (modern_usage)
+	    {
+	      error (0, 0, _("`-%ld' option is obsolete; omit it"),
+		     (long int) ocontext);
+	      try_help (0, 0);
+	    }
+	}
+    }
+
+  if (! tabsize)
+    tabsize = 8;
+  if (! width)
+    width = 130;
+
+  {
+    /* Maximize first the half line width, and then the gutter width,
+       according to the following constraints:
+
+	1.  Two half lines plus a gutter must fit in a line.
+	2.  If the half line width is nonzero:
+	    a.  The gutter width is at least GUTTER_WIDTH_MINIMUM.
+	    b.  If tabs are not expanded to spaces,
+		a half line plus a gutter is an integral number of tabs,
+		so that tabs in the right column line up.  */
+
+    intmax_t t = expand_tabs ? 1 : tabsize;
+    intmax_t w = width;
+    intmax_t off = (w + t + GUTTER_WIDTH_MINIMUM) / (2 * t)  *  t;
+    sdiff_half_width = MAX (0, MIN (off - GUTTER_WIDTH_MINIMUM, w - off)),
+    sdiff_column2_offset = sdiff_half_width ? off : w;
+  }
+
+  /* Make the horizon at least as large as the context, so that
+     shift_boundaries has more freedom to shift the first and last hunks.  */
+  if (horizon_lines < context)
+    horizon_lines = context;
+
+  summarize_regexp_list (&function_regexp_list);
+  summarize_regexp_list (&ignore_regexp_list);
+
+  if (output_style == OUTPUT_IFDEF)
+    {
+      for (i = 0; i < sizeof line_format / sizeof *line_format; i++)
+	if (!line_format[i])
+	  line_format[i] = "%l\n";
+      if (!group_format[OLD])
+	group_format[OLD]
+	  = group_format[CHANGED] ? group_format[CHANGED] : "%<";
+      if (!group_format[NEW])
+	group_format[NEW]
+	  = group_format[CHANGED] ? group_format[CHANGED] : "%>";
+      if (!group_format[UNCHANGED])
+	group_format[UNCHANGED] = "%=";
+      if (!group_format[CHANGED])
+	group_format[CHANGED] = concat (group_format[OLD],
+					group_format[NEW], "");
+    }
+
+  no_diff_means_no_output =
+    (output_style == OUTPUT_IFDEF ?
+      (!*group_format[UNCHANGED]
+       || (strcmp (group_format[UNCHANGED], "%=") == 0
+	   && !*line_format[UNCHANGED]))
+     : (output_style != OUTPUT_SDIFF) | suppress_common_lines);
+
+  files_can_be_treated_as_binary =
+    (brief & binary
+     & ~ (ignore_blank_lines | ignore_case | strip_trailing_cr
+	  | (ignore_regexp_list.regexps || ignore_white_space)));
+
+  switch_string = option_list (argv + 1, optind - 1);
+
+  if (from_file)
+    {
+      if (to_file)
+	fatal ("--from-file and --to-file both specified");
+      else
+	for (; optind < argc; optind++)
+	  {
+	    int status = compare_files ((struct comparison *) 0,
+					from_file, argv[optind]);
+	    if (exit_status < status)
+	      exit_status = status;
+	  }
+    }
+  else
+    {
+      if (to_file)
+	for (; optind < argc; optind++)
+	  {
+	    int status = compare_files ((struct comparison *) 0,
+					argv[optind], to_file);
+	    if (exit_status < status)
+	      exit_status = status;
+	  }
+      else
+	{
+	  if (argc - optind != 2)
+	    {
+	      if (argc - optind < 2)
+		try_help ("missing operand after `%s'", argv[argc - 1]);
+	      else
+		try_help ("extra operand `%s'", argv[optind + 2]);
+	    }
+
+	  exit_status = compare_files ((struct comparison *) 0,
+				       argv[optind], argv[optind + 1]);
+	}
+    }
+
+  /* Print any messages that were saved up for last.  */
+  print_message_queue ();
+
+  check_stdout ();
+  exit (exit_status);
+  return exit_status;
+}
+
+/* Append to REGLIST the regexp PATTERN.  */
+
+static void
+add_regexp (struct regexp_list *reglist, char const *pattern)
+{
+  size_t patlen = strlen (pattern);
+  char const *m = re_compile_pattern (pattern, patlen, reglist->buf);
+
+  if (m != 0)
+    error (0, 0, "%s: %s", pattern, m);
+  else
+    {
+      char *regexps = reglist->regexps;
+      size_t len = reglist->len;
+      bool multiple_regexps = reglist->multiple_regexps = regexps != 0;
+      size_t newlen = reglist->len = len + 2 * multiple_regexps + patlen;
+      size_t size = reglist->size;
+
+      if (size <= newlen)
+	{
+	  if (!size)
+	    size = 1;
+
+	  do size *= 2;
+	  while (size <= newlen);
+
+	  reglist->size = size;
+	  reglist->regexps = regexps = xrealloc (regexps, size);
+	}
+      if (multiple_regexps)
+	{
+	  regexps[len++] = '\\';
+	  regexps[len++] = '|';
+	}
+      memcpy (regexps + len, pattern, patlen + 1);
+    }
+}
+
+/* Ensure that REGLIST represents the disjunction of its regexps.
+   This is done here, rather than earlier, to avoid O(N^2) behavior.  */
+
+static void
+summarize_regexp_list (struct regexp_list *reglist)
+{
+  if (reglist->regexps)
+    {
+      /* At least one regexp was specified.  Allocate a fastmap for it.  */
+      reglist->buf->fastmap = xmalloc (1 << CHAR_BIT);
+      if (reglist->multiple_regexps)
+	{
+	  /* Compile the disjunction of the regexps.
+	     (If just one regexp was specified, it is already compiled.)  */
+	  char const *m = re_compile_pattern (reglist->regexps, reglist->len,
+					      reglist->buf);
+	  if (m != 0)
+	    error (EXIT_TROUBLE, 0, "%s: %s", reglist->regexps, m);
+	}
+    }
+}
+
+static void
+try_help (char const *reason_msgid, char const *operand)
+{
+  if (reason_msgid)
+    error (0, 0, _(reason_msgid), operand);
+  error (EXIT_TROUBLE, 0, _("Try `%s --help' for more information."),
+	 program_name);
+  abort ();
+}
+
+static void
+check_stdout (void)
+{
+  if (ferror (stdout))
+    fatal ("write failed");
+  else if (fclose (stdout) != 0)
+    pfatal_with_name (_("standard output"));
+}
+
+static char const * const option_help_msgid[] = {
+  N_("Compare files line by line."),
+  "",
+  N_("-i  --ignore-case  Ignore case differences in file contents."),
+  N_("--ignore-file-name-case  Ignore case when comparing file names."),
+  N_("--no-ignore-file-name-case  Consider case when comparing file names."),
+  N_("-E  --ignore-tab-expansion  Ignore changes due to tab expansion."),
+  N_("-b  --ignore-space-change  Ignore changes in the amount of white space."),
+  N_("-w  --ignore-all-space  Ignore all white space."),
+  N_("-B  --ignore-blank-lines  Ignore changes whose lines are all blank."),
+  N_("-I RE  --ignore-matching-lines=RE  Ignore changes whose lines all match RE."),
+  N_("--strip-trailing-cr  Strip trailing carriage return on input."),
+#if HAVE_SETMODE_DOS
+  N_("--binary  Read and write data in binary mode."),
+#endif
+  N_("-a  --text  Treat all files as text."),
+  "",
+  N_("-c  -C NUM  --context[=NUM]  Output NUM (default 3) lines of copied context.\n\
+-u  -U NUM  --unified[=NUM]  Output NUM (default 3) lines of unified context.\n\
+  --label LABEL  Use LABEL instead of file name.\n\
+  -p  --show-c-function  Show which C function each change is in.\n\
+  -F RE  --show-function-line=RE  Show the most recent line matching RE."),
+  N_("-q  --brief  Output only whether files differ."),
+  N_("-e  --ed  Output an ed script."),
+  N_("--normal  Output a normal diff."),
+  N_("-n  --rcs  Output an RCS format diff."),
+  N_("-y  --side-by-side  Output in two columns.\n\
+  -W NUM  --width=NUM  Output at most NUM (default 130) print columns.\n\
+  --left-column  Output only the left column of common lines.\n\
+  --suppress-common-lines  Do not output common lines."),
+  N_("-D NAME  --ifdef=NAME  Output merged file to show `#ifdef NAME' diffs."),
+  N_("--GTYPE-group-format=GFMT  Similar, but format GTYPE input groups with GFMT."),
+  N_("--line-format=LFMT  Similar, but format all input lines with LFMT."),
+  N_("--LTYPE-line-format=LFMT  Similar, but format LTYPE input lines with LFMT."),
+  N_("  LTYPE is `old', `new', or `unchanged'.  GTYPE is LTYPE or `changed'."),
+  N_("  GFMT may contain:\n\
+    %<  lines from FILE1\n\
+    %>  lines from FILE2\n\
+    %=  lines common to FILE1 and FILE2\n\
+    %[-][WIDTH][.[PREC]]{doxX}LETTER  printf-style spec for LETTER\n\
+      LETTERs are as follows for new group, lower case for old group:\n\
+        F  first line number\n\
+        L  last line number\n\
+        N  number of lines = L-F+1\n\
+        E  F-1\n\
+        M  L+1"),
+  N_("  LFMT may contain:\n\
+    %L  contents of line\n\
+    %l  contents of line, excluding any trailing newline\n\
+    %[-][WIDTH][.[PREC]]{doxX}n  printf-style spec for input line number"),
+  N_("  Either GFMT or LFMT may contain:\n\
+    %%  %\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 <bug-gnu-utils@gnu.org>."),
+  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;
+}