Import GNU diffutils 2.7

Note, this is going to be messy.. 2.3 was vendor-branch imported, while
2.6 was done as a delta. Sigh.  I'm importing this on a vendor branch so
that it will be easier to deal with next time..

(cvs-1.6 wants rcs-5.7, and rcs-5.7 suggests diffutils-2.7)

1 files changed, 343 insertions, 164 deletions

diff --git a/gnu/usr.bin/diff/diff.c b/gnu/usr.bin/diff/diff.c
index e4eb66f..ab1549b 100644
--- a/gnu/usr.bin/diff/diff.c
+++ b/gnu/usr.bin/diff/diff.c
@@ -1,5 +1,5 @@
 /* GNU DIFF main routine.
-   Copyright (C) 1988, 1989, 1992 Free Software Foundation, Inc.
+   Copyright (C) 1988, 1989, 1992, 1993, 1994 Free Software Foundation, Inc.
 
 This file is part of GNU DIFF.
 
@@ -22,6 +22,7 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 
 #define GDIFF_MAIN
 #include "diff.h"
+#include <signal.h>
 #include "getopt.h"
 #include "fnmatch.h"
 
@@ -33,14 +34,18 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #define GUTTER_WIDTH_MINIMUM 3
 #endif
 
-int diff_dirs ();
-int diff_2_files ();
-
-static int compare_files ();
-static int specify_format ();
-static void add_regexp();
-static void specify_style ();
-static void usage ();
+static char const *filetype PARAMS((struct stat const *));
+static char *option_list PARAMS((char **, int));
+static int add_exclude_file PARAMS((char const *));
+static int ck_atoi PARAMS((char const *, int *));
+static int compare_files PARAMS((char const *, char const *, char const *, char const *, int));
+static int specify_format PARAMS((char **, char *));
+static void add_exclude PARAMS((char const *));
+static void add_regexp PARAMS((struct regexp_list **, char const *));
+static void specify_style PARAMS((enum output_style));
+static void try_help PARAMS((char const *));
+static void check_stdout PARAMS((void));
+static void usage PARAMS((void));
 
 /* Nonzero for -r: if comparing two directories,
    compare their common subdirectories recursively.  */
@@ -51,6 +56,11 @@ static int recursive;
 
 int no_discards;
 
+#if HAVE_SETMODE
+/* I/O mode: nonzero only if using binary input/output.  */
+static int binary_I_O;
+#endif
+
 /* 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.
@@ -65,13 +75,13 @@ option_list (optionvec, count)
      int count;
 {
   int i;
-  int length = 0;
+  size_t length = 0;
   char *result;
 
   for (i = 0; i < count; i++)
     length += strlen (optionvec[i]) + 1;
 
-  result = (char *) xmalloc (length + 1);
+  result = xmalloc (length + 1);
   result[0] = 0;
 
   for (i = 0; i < count; i++)
@@ -83,14 +93,14 @@ option_list (optionvec, count)
   return result;
 }
 
-/* Convert STR to a positive integer, storing the result in *OUT. 
+/* Convert STR to a positive integer, storing the result in *OUT.
    If STR is not a valid integer, return -1 (otherwise 0). */
 static int
 ck_atoi (str, out)
-     char *str;
+     char const *str;
      int *out;
 {
-  char *p;
+  char const *p;
   for (p = str; *p; p++)
     if (*p < '0' || *p > '9')
       return -1;
@@ -101,12 +111,12 @@ ck_atoi (str, out)
 
 /* Keep track of excluded file name patterns.  */
 
-static const char **exclude;
+static char const **exclude;
 static int exclude_alloc, exclude_count;
 
 int
 excluded_filename (f)
-     const char *f;
+     char const *f;
 {
   int i;
   for (i = 0;  i < exclude_count;  i++)
@@ -117,10 +127,10 @@ excluded_filename (f)
 
 static void
 add_exclude (pattern)
-     const char *pattern;
+     char const *pattern;
 {
   if (exclude_alloc <= exclude_count)
-    exclude = (const char **)
+    exclude = (char const **)
 	      (exclude_alloc == 0
 	       ? xmalloc ((exclude_alloc = 64) * sizeof (*exclude))
 	       : xrealloc (exclude, (exclude_alloc *= 2) * sizeof (*exclude)));
@@ -130,13 +140,15 @@ add_exclude (pattern)
 
 static int
 add_exclude_file (name)
-     const char *name;
+     char const *name;
 {
   struct file_data f;
   char *p, *q, *lim;
 
   f.name = optarg;
-  f.desc = strcmp (optarg, "-") == 0 ? 0 : open (optarg, O_RDONLY, 0);
+  f.desc = (strcmp (optarg, "-") == 0
+	    ? STDIN_FILENO
+	    : open (optarg, O_RDONLY, 0));
   if (f.desc < 0 || fstat (f.desc, &f.stat) != 0)
     return -1;
 
@@ -145,7 +157,7 @@ add_exclude_file (name)
 
   for (p = f.buffer, lim = p + f.buffered_chars;  p < lim;  p = q)
     {
-      q = memchr (p, '\n', lim - p);
+      q = (char *) memchr (p, '\n', lim - p);
       if (!q)
 	q = lim;
       *q++ = 0;
@@ -158,7 +170,7 @@ add_exclude_file (name)
 /* The numbers 129- that appear in the fourth element of some entries
    tell the big switch in `main' how to process those options.  */
 
-static struct option longopts[] =
+static struct option const longopts[] =
 {
   {"ignore-blank-lines", 0, 0, 'B'},
   {"context", 2, 0, 'C'},
@@ -185,7 +197,6 @@ static struct option longopts[] =
   {"print", 0, 0, 'l'},		/* An alias, no longer recommended */
   {"rcs", 0, 0, 'n'},
   {"show-c-function", 0, 0, 'p'},
-  {"binary", 0, 0, 'q'},	/* An alias, no longer recommended */
   {"brief", 0, 0, 'q'},
   {"recursive", 0, 0, 'r'},
   {"report-identical-files", 0, 0, 's'},
@@ -202,11 +213,14 @@ static struct option longopts[] =
   {"old-line-format", 1, 0, 132},
   {"new-line-format", 1, 0, 133},
   {"unchanged-line-format", 1, 0, 134},
-  {"old-group-format", 1, 0, 135},
-  {"new-group-format", 1, 0, 136},
-  {"unchanged-group-format", 1, 0, 137},
-  {"changed-group-format", 1, 0, 138},
-  {"horizon-lines", 1, 0, 139},
+  {"line-format", 1, 0, 135},
+  {"old-group-format", 1, 0, 136},
+  {"new-group-format", 1, 0, 137},
+  {"unchanged-group-format", 1, 0, 138},
+  {"changed-group-format", 1, 0, 139},
+  {"horizon-lines", 1, 0, 140},
+  {"help", 0, 0, 141},
+  {"binary", 0, 0, 142},
   {0, 0, 0, 0}
 };
 
@@ -218,42 +232,20 @@ main (argc, argv)
   int val;
   int c;
   int prev = -1;
-  extern char *version_string;
   int width = DEFAULT_WIDTH;
+  int show_c_function = 0;
 
-  program = argv[0];
-
-  /* Do our initializations. */
+  /* Do our initializations.  */
+  initialize_main (&argc, &argv);
+  program_name = argv[0];
   output_style = OUTPUT_NORMAL;
-  always_text_flag = FALSE;
-  ignore_space_change_flag = FALSE;
-  ignore_all_space_flag = FALSE;
-  length_varies = FALSE;
-  ignore_case_flag = FALSE;
-  ignore_blank_lines_flag = FALSE;
-  ignore_regexp_list = NULL;
-  function_regexp_list = NULL;
-  print_file_same_flag = FALSE;
-  entire_new_file_flag = FALSE;
-  unidirectional_new_file_flag = FALSE;
-  no_details_flag = FALSE;
   context = -1;
-  line_end_char = '\n';
-  tab_align_flag = FALSE;
-  tab_expand_flag = FALSE;
-  recursive = FALSE;
-  paginate_flag = FALSE;
-  heuristic = FALSE;
-  dir_start_file = NULL;
-  msg_chain = NULL;
-  msg_chain_end = NULL;
-  no_discards = 0;
 
   /* Decode the options.  */
 
   while ((c = getopt_long (argc, argv,
 			   "0123456789abBcC:dD:efF:hHiI:lL:nNpPqrsS:tTuU:vwW:x:X:y",
-			   longopts, (int *)0)) != EOF)
+			   longopts, 0)) != EOF)
     {
       switch (c)
 	{
@@ -285,14 +277,16 @@ main (argc, argv)
 	  break;
 
 	case 'b':
-	  /* Ignore changes in amount of whitespace.  */
+	  /* Ignore changes in amount of white space.  */
 	  ignore_space_change_flag = 1;
-	  length_varies = 1;
+	  ignore_some_changes = 1;
+	  ignore_some_line_changes = 1;
 	  break;
 
 	case 'B':
 	  /* Ignore changes affecting only blank lines.  */
 	  ignore_blank_lines_flag = 1;
+	  ignore_some_changes = 1;
 	  break;
 
 	case 'C':		/* +context[=lines] */
@@ -323,7 +317,7 @@ main (argc, argv)
 	  specify_style (OUTPUT_IFDEF);
 	  {
 	    int i, err = 0;
-	    static const char C_ifdef_group_formats[] =
+	    static char const C_ifdef_group_formats[] =
 	      "#ifndef %s\n%%<#endif /* not %s */\n%c#ifdef %s\n%%>#endif /* %s */\n%c%%=%c#ifndef %s\n%%<#else /* %s */\n%%>#endif /* %s */\n";
 	    char *b = xmalloc (sizeof (C_ifdef_group_formats)
 			       + 7 * strlen(optarg) - 14 /* 7*"%s" */
@@ -376,17 +370,28 @@ main (argc, argv)
 	case 'i':
 	  /* Ignore changes in case.  */
 	  ignore_case_flag = 1;
+	  ignore_some_changes = 1;
+	  ignore_some_line_changes = 1;
 	  break;
 
 	case 'I':
 	  /* Ignore changes affecting only lines that match the
 	     specified regexp.  */
 	  add_regexp (&ignore_regexp_list, optarg);
+	  ignore_some_changes = 1;
 	  break;
 
 	case 'l':
 	  /* Pass the output through `pr' to paginate it.  */
 	  paginate_flag = 1;
+#if !defined(SIGCHLD) && defined(SIGCLD)
+#define SIGCHLD SIGCLD
+#endif
+#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':
@@ -398,7 +403,7 @@ main (argc, argv)
 	  else
 	    fatal ("too many file label options");
 	  break;
-	  
+
 	case 'n':
 	  /* Output RCS-style diffs, like `-f' except that each command
 	     specifies the number of lines affected.  */
@@ -413,7 +418,7 @@ main (argc, argv)
 
 	case 'p':
 	  /* Make context-style output and show name of last C function.  */
-	  specify_style (OUTPUT_CONTEXT);
+	  show_c_function = 1;
 	  add_regexp (&function_regexp_list, "^[_a-zA-Z$]");
 	  break;
 
@@ -429,7 +434,7 @@ main (argc, argv)
 	  break;
 
 	case 'r':
-	  /* When comparing directories, 
+	  /* When comparing directories,
 	     recursively compare any subdirectories found.  */
 	  recursive = 1;
 	  break;
@@ -464,13 +469,14 @@ main (argc, argv)
 	  break;
 
 	case 'v':
-	  fprintf (stderr, "GNU diff version %s\n", version_string);
-	  break;
+	  printf ("diff - GNU diffutils version %s\n", version_string);
+	  exit (0);
 
 	case 'w':
-	  /* Ignore horizontal whitespace when comparing lines.  */
+	  /* Ignore horizontal white space when comparing lines.  */
 	  ignore_all_space_flag = 1;
-	  length_varies = 1;
+	  ignore_some_changes = 1;
+	  ignore_some_line_changes = 1;
 	  break;
 
 	case 'x':
@@ -492,15 +498,15 @@ main (argc, argv)
 	  if (ck_atoi (optarg, &width) || width <= 0)
 	    fatal ("column width must be a positive integer");
 	  break;
-	  
+
 	case 129:
 	  sdiff_left_only = 1;
 	  break;
-	  
+
 	case 130:
 	  sdiff_skip_common_lines = 1;
 	  break;
-	  
+
 	case 131:
 	  /* sdiff-style columns output. */
 	  specify_style (OUTPUT_SDIFF);
@@ -511,40 +517,57 @@ main (argc, argv)
 	case 133:
 	case 134:
 	  specify_style (OUTPUT_IFDEF);
+	  if (specify_format (&line_format[c - 132], optarg) != 0)
+	    error ("conflicting line format", 0, 0);
+	  break;
+
+	case 135:
+	  specify_style (OUTPUT_IFDEF);
 	  {
-	    const char **form = &line_format[c - 132];
-	    if (*form && strcmp (*form, optarg) != 0)
+	    int i, err = 0;
+	    for (i = 0; i < sizeof (line_format) / sizeof (*line_format); i++)
+	      err |= specify_format (&line_format[i], optarg);
+	    if (err)
 	      error ("conflicting line format", 0, 0);
-	    *form = optarg;
 	  }
 	  break;
 
-	case 135:
 	case 136:
 	case 137:
 	case 138:
+	case 139:
 	  specify_style (OUTPUT_IFDEF);
-	  {
-	    const char **form = &group_format[c - 135];
-	    if (*form && strcmp (*form, optarg) != 0)
-	      error ("conflicting group format", 0, 0);
-	    *form = optarg;
-	  }
+	  if (specify_format (&group_format[c - 136], optarg) != 0)
+	    error ("conflicting group format", 0, 0);
 	  break;
 
-	case 139:
+	case 140:
 	  if (ck_atoi (optarg, &horizon_lines) || horizon_lines < 0)
 	    fatal ("horizon must be a nonnegative integer");
 	  break;
 
-	default:
+	case 141:
 	  usage ();
+	  check_stdout ();
+	  exit (0);
+
+	case 142:
+	  /* Use binary I/O when reading and writing data.
+	     On Posix hosts, this has no effect.  */
+#if HAVE_SETMODE
+	  binary_I_O = 1;
+	  setmode (STDOUT_FILENO, O_BINARY);
+#endif
+	  break;
+
+	default:
+	  try_help (0);
 	}
       prev = c;
     }
 
-  if (optind != argc - 2)
-    usage ();
+  if (argc - optind != 2)
+    try_help (argc - optind < 2 ? "missing operand" : "extra operand");
 
 
   {
@@ -564,14 +587,21 @@ main (argc, argv)
     sdiff_column2_offset = sdiff_half_width ? off : width;
   }
 
+  if (show_c_function && output_style != OUTPUT_UNIFIED)
+    specify_style (OUTPUT_CONTEXT);
+
   if (output_style != OUTPUT_CONTEXT && output_style != OUTPUT_UNIFIED)
     context = 0;
   else if (context == -1)
     /* Default amount of context for -c.  */
     context = 3;
- 
+
   if (output_style == OUTPUT_IFDEF)
     {
+      /* Format arrays are char *, not char const *,
+	 because integer formats are temporarily modified.
+	 But it is safe to assign a constant like "%=" to a format array,
+	 since "%=" does not format any integers.  */
       int i;
       for (i = 0; i < sizeof (line_format) / sizeof (*line_format); i++)
 	if (!line_format[i])
@@ -598,13 +628,12 @@ main (argc, argv)
 
   switch_string = option_list (argv + 1, optind - 1);
 
-  val = compare_files (NULL, argv[optind], NULL, argv[optind + 1], 0);
+  val = compare_files (0, argv[optind], 0, argv[optind + 1], 0);
 
   /* Print any messages that were saved up for last.  */
   print_message_queue ();
 
-  if (ferror (stdout) || fclose (stdout) != 0)
-    fatal ("write error");
+  check_stdout ();
   exit (val);
   return val;
 }
@@ -614,14 +643,14 @@ main (argc, argv)
 static void
 add_regexp (reglist, pattern)
      struct regexp_list **reglist;
-     char *pattern;
+     char const *pattern;
 {
   struct regexp_list *r;
-  const char *m;
+  char const *m;
 
   r = (struct regexp_list *) xmalloc (sizeof (*r));
   bzero (r, sizeof (*r));
-  r->buf.fastmap = (char *) xmalloc (256);
+  r->buf.fastmap = xmalloc (256);
   m = re_compile_pattern (pattern, strlen (pattern), &r->buf);
   if (m != 0)
     error ("%s: %s", pattern, m);
@@ -632,37 +661,102 @@ add_regexp (reglist, pattern)
 }
 
 static void
-usage ()
+try_help (reason)
+     char const *reason;
 {
-  fprintf (stderr, "Usage: %s [options] from-file to-file\n", program);
-  fprintf (stderr, "Options:\n\
-       [-abBcdefhHilnNpPqrstTuvwy] [-C lines] [-D name] [-F regexp]\n\
-       [-I regexp] [-L from-label [-L to-label]] [-S starting-file] [-U lines]\n\
-       [-W columns] [-x pattern] [-X pattern-file] [--exclude=pattern]\n\
-       [--exclude-from=pattern-file] [--ignore-blank-lines] [--context[=lines]]\n\
-       [--ifdef=name] [--show-function-line=regexp] [--speed-large-files]\n\
-       [--label=from-label [--label=to-label]] [--new-file]\n");
-  fprintf (stderr, "\
-       [--ignore-matching-lines=regexp] [--unidirectional-new-file]\n\
-       [--starting-file=starting-file] [--initial-tab] [--width=columns]\n\
-       [--text] [--ignore-space-change] [--minimal] [--ed] [--forward-ed]\n\
-       [--ignore-case] [--paginate] [--rcs] [--show-c-function] [--brief]\n\
-       [--recursive] [--report-identical-files] [--expand-tabs] [--version]\n");
-  fprintf (stderr, "\
-       [--ignore-all-space] [--side-by-side] [--unified[=lines]]\n\
-       [--left-column] [--suppress-common-lines] [--sdiff-merge-assist]\n\
-       [--old-line-format=format] [--new-line-format=format]\n\
-       [--unchanged-line-format=format]\n\
-       [--old-group-format=format] [--new-group-format=format]\n\
-       [--unchanged-group-format=format] [--changed-group-format=format]\n\
-       [--horizon-lines=lines]\n");
+  if (reason)
+    error ("%s", reason, 0);
+  error ("Try `%s --help' for more information.", program_name, 0);
   exit (2);
-} 
+}
+
+static void
+check_stdout ()
+{
+  if (ferror (stdout) || fclose (stdout) != 0)
+    fatal ("write error");
+}
+
+static char const * const option_help[] = {
+"-i  --ignore-case  Consider upper- and lower-case to be the same.",
+"-w  --ignore-all-space  Ignore all white space.",
+"-b  --ignore-space-change  Ignore changes in the amount of white space.",
+"-B  --ignore-blank-lines  Ignore changes whose lines are all blank.",
+"-I RE  --ignore-matching-lines=RE  Ignore changes whose lines all match RE.",
+#if HAVE_SETMODE
+"--binary  Read and write data in binary mode.",
+#endif
+"-a  --text  Treat all files as text.\n",
+"-c  -C NUM  --context[=NUM]  Output NUM (default 2) lines of copied context.",
+"-u  -U NUM  --unified[=NUM]  Output NUM (default 2) lines of unified context.",
+"  -NUM  Use NUM context lines.",
+"  -L LABEL  --label LABEL  Use LABEL instead of file name.",
+"  -p  --show-c-function  Show which C function each change is in.",
+"  -F RE  --show-function-line=RE  Show the most recent line matching RE.",
+"-q  --brief  Output only whether files differ.",
+"-e  --ed  Output an ed script.",
+"-n  --rcs  Output an RCS format diff.",
+"-y  --side-by-side  Output in two columns.",
+"  -w NUM  --width=NUM  Output at most NUM (default 130) characters per line.",
+"  --left-column  Output only the left column of common lines.",
+"  --suppress-common-lines  Do not output common lines.",
+"-DNAME  --ifdef=NAME  Output merged file to show `#ifdef NAME' diffs.",
+"--GTYPE-group-format=GFMT  Similar, but format GTYPE input groups with GFMT.",
+"--line-format=LFMT  Similar, but format all input lines with LFMT.",
+"--LTYPE-line-format=LFMT  Similar, but format LTYPE input lines with LFMT.",
+"  LTYPE is `old', `new', or `unchanged'.  GTYPE is LTYPE or `changed'.",
+"  GFMT may contain:",
+"    %<  lines from FILE1",
+"    %>  lines from FILE2",
+"    %=  lines common to FILE1 and FILE2",
+"    %[-][WIDTH][.[PREC]]{doxX}LETTER  printf-style spec for LETTER",
+"      LETTERs are as follows for new group, lower case for old group:",
+"        F  first line number",
+"        L  last line number",
+"        N  number of lines = L-F+1",
+"        E  F-1",
+"        M  L+1",
+"  LFMT may contain:",
+"    %L  contents of line",
+"    %l  contents of line, excluding any trailing newline",
+"    %[-][WIDTH][.[PREC]]{doxX}n  printf-style spec for input line number",
+"  Either GFMT or LFMT may contain:",
+"    %%  %",
+"    %c'C'  the single character C",
+"    %c'\\OOO'  the character with octal code OOO\n",
+"-l  --paginate  Pass the output through `pr' to paginate it.",
+"-t  --expand-tabs  Expand tabs to spaces in output.",
+"-T  --initial-tab  Make tabs line up by prepending a tab.\n",
+"-r  --recursive  Recursively compare any subdirectories found.",
+"-N  --new-file  Treat absent files as empty.",
+"-P  --unidirectional-new-file  Treat absent first files as empty.",
+"-s  --report-identical-files  Report when two files are the same.",
+"-x PAT  --exclude=PAT  Exclude files that match PAT.",
+"-X FILE  --exclude-from=FILE  Exclude files that match any pattern in FILE.",
+"-S FILE  --starting-file=FILE  Start with FILE when comparing directories.\n",
+"--horizon-lines=NUM  Keep NUM lines of the common prefix and suffix.",
+"-d  --minimal  Try hard to find a smaller set of changes.",
+"-H  --speed-large-files  Assume large files and many scattered small changes.\n",
+"-v  --version  Output version info.",
+"--help  Output this help.",
+0
+};
+
+static void
+usage ()
+{
+  char const * const *p;
+
+  printf ("Usage: %s [OPTION]... FILE1 FILE2\n\n", program_name);
+  for (p = option_help;  *p;  p++)
+    printf ("  %s\n", *p);
+  printf ("\nIf FILE1 or FILE2 is `-', read standard input.\n");
+}
 
 static int
 specify_format (var, value)
-     const char **var;
-     const char *value;
+     char **var;
+     char *value;
 {
   int err = *var ? strcmp (*var, value) : 0;
   *var = value;
@@ -679,6 +773,57 @@ specify_style (style)
   output_style = style;
 }
 
+static char const *
+filetype (st)
+     struct stat const *st;
+{
+  /* See Posix.2 section 4.17.6.1.1 and Table 5-1 for these formats.
+     To keep diagnostics grammatical, the returned string must start
+     with a consonant.  */
+
+  if (S_ISREG (st->st_mode))
+    {
+      if (st->st_size == 0)
+	return "regular empty file";
+      /* Posix.2 section 5.14.2 seems to suggest that we must read the file
+	 and guess whether it's C, Fortran, etc., but this is somewhat useless
+	 and doesn't reflect historical practice.  We're allowed to guess
+	 wrong, so we don't bother to read the file.  */
+      return "regular file";
+    }
+  if (S_ISDIR (st->st_mode)) return "directory";
+
+  /* other Posix.1 file types */
+#ifdef S_ISBLK
+  if (S_ISBLK (st->st_mode)) return "block special file";
+#endif
+#ifdef S_ISCHR
+  if (S_ISCHR (st->st_mode)) return "character special file";
+#endif
+#ifdef S_ISFIFO
+  if (S_ISFIFO (st->st_mode)) return "fifo";
+#endif
+
+  /* other Posix.1b file types */
+#ifdef S_TYPEISMQ
+  if (S_TYPEISMQ (st)) return "message queue";
+#endif
+#ifdef S_TYPEISSEM
+  if (S_TYPEISSEM (st)) return "semaphore";
+#endif
+#ifdef S_TYPEISSHM
+  if (S_TYPEISSHM (st)) return "shared memory object";
+#endif
+
+  /* other popular file types */
+  /* S_ISLNK is impossible with `fstat' and `stat'.  */
+#ifdef S_ISSOCK
+  if (S_ISSOCK (st->st_mode)) return "socket";
+#endif
+
+  return "weird file";
+}
+
 /* Compare two files (or dirs) with specified names
    DIR0/NAME0 and DIR1/NAME1, at level DEPTH in directory recursion.
    (if DIR0 is 0, then the name is just NAME0, etc.)
@@ -689,15 +834,16 @@ specify_style (style)
 
 static int
 compare_files (dir0, name0, dir1, name1, depth)
-     char *dir0, *dir1;
-     char *name0, *name1;
+     char const *dir0, *dir1;
+     char const *name0, *name1;
      int depth;
 {
   struct file_data inf[2];
   register int i;
   int val;
   int same_files;
-  int errorcount = 0;
+  int failed = 0;
+  char *free0 = 0, *free1 = 0;
 
   /* If this is directory comparison, perhaps we have a file
      that exists only in one of the directories.
@@ -707,15 +853,17 @@ compare_files (dir0, name0, dir1, name1, depth)
 	 || (unidirectional_new_file_flag && name1 != 0)
 	 || entire_new_file_flag))
     {
-      char *name = name0 == 0 ? name1 : name0;
-      char *dir = name0 == 0 ? dir1 : dir0;
+      char const *name = name0 == 0 ? name1 : name0;
+      char const *dir = name0 == 0 ? dir1 : dir0;
       message ("Only in %s: %s\n", dir, name);
       /* Return 1 so that diff_dirs will return 1 ("some files differ").  */
       return 1;
     }
 
+  bzero (inf, sizeof (inf));
+
   /* Mark any nonexistent file with -1 in the desc field.  */
-  /* Mark unopened files (i.e. directories) with -2. */
+  /* Mark unopened files (e.g. directories) with -2. */
 
   inf[0].desc = name0 == 0 ? -1 : -2;
   inf[1].desc = name1 == 0 ? -1 : -2;
@@ -727,25 +875,41 @@ compare_files (dir0, name0, dir1, name1, depth)
   if (name1 == 0)
     name1 = name0;
 
-  inf[0].name = dir0 == 0 ? name0 : concat (dir0, "/", name0);
-  inf[1].name = dir1 == 0 ? name1 : concat (dir1, "/", name1);
+  inf[0].name = dir0 == 0 ? name0 : (free0 = dir_file_pathname (dir0, name0));
+  inf[1].name = dir1 == 0 ? name1 : (free1 = dir_file_pathname (dir1, name1));
 
   /* Stat the files.  Record whether they are directories.  */
 
   for (i = 0; i <= 1; i++)
     {
-      bzero (&inf[i].stat, sizeof (struct stat));
-      inf[i].dir_p = 0;
-
       if (inf[i].desc != -1)
 	{
 	  int stat_result;
 
-	  if (strcmp (inf[i].name, "-") == 0)
+	  if (i && filename_cmp (inf[i].name, inf[0].name) == 0)
 	    {
-	      inf[i].desc = 0;
-	      inf[i].name = "Standard Input";
-	      stat_result = fstat (0, &inf[i].stat);
+	      inf[i].stat = inf[0].stat;
+	      stat_result = 0;
+	    }
+	  else if (strcmp (inf[i].name, "-") == 0)
+	    {
+	      inf[i].desc = STDIN_FILENO;
+	      stat_result = fstat (STDIN_FILENO, &inf[i].stat);
+	      if (stat_result == 0 && S_ISREG (inf[i].stat.st_mode))
+		{
+		  off_t pos = lseek (STDIN_FILENO, (off_t) 0, SEEK_CUR);
+		  if (pos == -1)
+		    stat_result = -1;
+		  else
+		    {
+		      if (pos <= inf[i].stat.st_size)
+			inf[i].stat.st_size -= pos;
+		      else
+			inf[i].stat.st_size = 0;
+		      /* Posix.2 4.17.6.1.4 requires current time for stdin.  */
+		      time (&inf[i].stat.st_mtime);
+		    }
+		}
 	    }
 	  else
 	    stat_result = stat (inf[i].name, &inf[i].stat);
@@ -753,42 +917,46 @@ compare_files (dir0, name0, dir1, name1, depth)
 	  if (stat_result != 0)
 	    {
 	      perror_with_name (inf[i].name);
-	      errorcount = 1;
+	      failed = 1;
 	    }
 	  else
-	    inf[i].dir_p = S_ISDIR (inf[i].stat.st_mode) && inf[i].desc != 0;
+	    {
+	      inf[i].dir_p = S_ISDIR (inf[i].stat.st_mode) && inf[i].desc != 0;
+	      if (inf[1 - i].desc == -1)
+		{
+		  inf[1 - i].dir_p = inf[i].dir_p;
+		  inf[1 - i].stat.st_mode = inf[i].stat.st_mode;
+		}
+	    }
 	}
     }
 
-  if (name0 == 0)
-    inf[0].dir_p = inf[1].dir_p;
-  if (name1 == 0)
-    inf[1].dir_p = inf[0].dir_p;
-
-  if (errorcount == 0 && depth == 0 && inf[0].dir_p != inf[1].dir_p)
+  if (! failed && depth == 0 && inf[0].dir_p != inf[1].dir_p)
     {
       /* 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 = inf[0].dir_p;
       int dir_arg = 1 - fnm_arg;
-      char *p = rindex (inf[fnm_arg].name, '/');
-      char *filename = inf[dir_arg].name
-	= concat (inf[dir_arg].name,  "/", (p ? p+1 : inf[fnm_arg].name));
+      char const *fnm = inf[fnm_arg].name;
+      char const *dir = inf[dir_arg].name;
+      char const *p = filename_lastdirchar (fnm);
+      char const *filename = inf[dir_arg].name
+	= dir_file_pathname (dir, p ? p + 1 : fnm);
 
-      if (inf[fnm_arg].desc == 0)
+      if (strcmp (fnm, "-") == 0)
 	fatal ("can't compare - to a directory");
 
       if (stat (filename, &inf[dir_arg].stat) != 0)
 	{
 	  perror_with_name (filename);
-	  errorcount = 1;
+	  failed = 1;
 	}
       else
 	inf[dir_arg].dir_p = S_ISDIR (inf[dir_arg].stat.st_mode);
     }
 
-  if (errorcount)
+  if (failed)
     {
 
       /* If either file should exist but does not, return 2.  */
@@ -796,10 +964,8 @@ compare_files (dir0, name0, dir1, name1, depth)
       val = 2;
 
     }
-  else if ((same_files =    inf[0].stat.st_ino == inf[1].stat.st_ino
-			 && inf[0].stat.st_dev == inf[1].stat.st_dev
-			 && inf[0].desc != -1
-			 && inf[1].desc != -1)
+  else if ((same_files = inf[0].desc != -1 && inf[1].desc != -1
+			 && 0 < same_file (&inf[0].stat, &inf[1].stat))
 	   && no_diff_means_no_output)
     {
       /* The two named files are actually the same physical file.
@@ -828,37 +994,43 @@ compare_files (dir0, name0, dir1, name1, depth)
 	}
 
     }
-  else if (inf[0].dir_p | inf[1].dir_p)
+  else if ((inf[0].dir_p | inf[1].dir_p)
+	   || (depth > 0
+	       && (! S_ISREG (inf[0].stat.st_mode)
+		   || ! S_ISREG (inf[1].stat.st_mode))))
     {
       /* Perhaps we have a subdirectory that exists only in one directory.
 	 If so, just print a message to that effect.  */
 
       if (inf[0].desc == -1 || inf[1].desc == -1)
 	{
-	  if (recursive
+	  if ((inf[0].dir_p | inf[1].dir_p)
+	      && recursive
 	      && (entire_new_file_flag
 		  || (unidirectional_new_file_flag && inf[0].desc == -1)))
 	    val = diff_dirs (inf, compare_files, depth);
 	  else
 	    {
-	      char *dir = (inf[0].desc == -1) ? dir1 : dir0;
+	      char const *dir = (inf[0].desc == -1) ? dir1 : dir0;
+	      /* See Posix.2 section 4.17.6.1.1 for this format.  */
 	      message ("Only in %s: %s\n", dir, name0);
 	      val = 1;
 	    }
 	}
       else
 	{
-	  /* We have a subdirectory in one directory
-	     and a file in the other.  */
+	  /* We have two files that are not to be compared.  */
 
-	  message ("%s is a directory but %s is not\n",
-		   inf[1 - inf[0].dir_p].name, inf[inf[0].dir_p].name);
+	  /* See Posix.2 section 4.17.6.1.1 for this format.  */
+	  message5 ("File %s is a %s while file %s is a %s\n",
+		    inf[0].name, filetype (&inf[0].stat),
+		    inf[1].name, filetype (&inf[1].stat));
 
 	  /* This is a difference.  */
 	  val = 1;
 	}
     }
-  else if (no_details_flag
+  else if ((no_details_flag & ~ignore_some_changes)
 	   && inf[0].stat.st_size != inf[1].stat.st_size
 	   && (inf[0].desc == -1 || S_ISREG (inf[0].stat.st_mode))
 	   && (inf[1].desc == -1 || S_ISREG (inf[1].stat.st_mode)))
@@ -876,7 +1048,7 @@ compare_files (dir0, name0, dir1, name1, depth)
 	if ((inf[0].desc = open (inf[0].name, O_RDONLY, 0)) < 0)
 	  {
 	    perror_with_name (inf[0].name);
-	    errorcount = 1;
+	    failed = 1;
 	  }
       if (inf[1].desc == -2)
 	if (same_files)
@@ -884,12 +1056,19 @@ compare_files (dir0, name0, dir1, name1, depth)
 	else if ((inf[1].desc = open (inf[1].name, O_RDONLY, 0)) < 0)
 	  {
 	    perror_with_name (inf[1].name);
-	    errorcount = 1;
+	    failed = 1;
 	  }
-    
+
+#if HAVE_SETMODE
+      if (binary_I_O)
+	for (i = 0; i <= 1; i++)
+	  if (0 <= inf[i].desc)
+	    setmode (inf[i].desc, O_BINARY);
+#endif
+
       /* Compare the files, if no error was found.  */
 
-      val = errorcount ? 2 : diff_2_files (inf, depth);
+      val = failed ? 2 : diff_2_files (inf, depth);
 
       /* Close the file descriptors.  */
 
@@ -918,10 +1097,10 @@ compare_files (dir0, name0, dir1, name1, depth)
   else
     fflush (stdout);
 
-  if (dir0 != 0)
-    free (inf[0].name);
-  if (dir1 != 0)
-    free (inf[1].name);
+  if (free0)
+    free (free0);
+  if (free1)
+    free (free1);
 
   return val;
 }