/* GNU DIFF main routine.
   Copyright (C) 1988, 1989 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 1, 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, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* GNU DIFF was written by Mike Haertel, David Hayes,
   Richard Stallman and Len Tower.  */

#define GDIFF_MAIN
#include "regex.h"
#include "diff.h"
#include "getopt.h"


/* Nonzero for -r: if comparing two directories,
   compare their common subdirectories recursively.  */

int recursive;

/* Nonzero for -Q: quick and dirty VM saving compare, no details */
/* (implies -q) */

int quick_and_dirty;

/* Nonzero for -X: check extra junk that we ordinarily skip */

int extended_tests;

/* For debugging: don't do discard_confusing_lines.  */

int no_discards;

/* 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 (optionvec, count)
     char **optionvec;  /* Was `vector', but that collides on Alliant.  */
     int count;
{
  int i;
  int length = 0;
  char *result;

  for (i = 0; i < count; i++)
    length += strlen (optionvec[i]) + 1;

  result = (char *) xmalloc (length + 1);
  result[0] = 0;

  for (i = 0; i < count; i++)
    {
      strcat (result, " ");
      strcat (result, optionvec[i]);
    }

  return result;
}

static struct option longopts[] =
{
  {"ignore-blank-lines", 0, 0, 'B'},
  {"context", 2, 0, 129},
  {"ifdef", 1, 0, 'D'},
  {"show-function-line", 1, 0, 'F'},
  {"speed-large-files", 0, 0, 'H'},
  {"ignore-matching-lines", 1, 0, 'I'},
  {"entire-new-file", 0, 0, 'N'},
  {"starting-file", 1, 0, 'S'},
  {"initial-tab", 0, 0, 'T'},
  {"text", 0, 0, 'a'},
  {"all-text", 0, 0, 'a'},
  {"ascii", 0, 0, 'a'},
  {"ignore-space-change", 0, 0, 'b'},
  {"minimal", 0, 0, 'd'},
  {"ed", 0, 0, 'e'},
  {"reversed-ed", 0, 0, 'f'},
  {"ignore-case", 0, 0, 'i'},
  {"print", 0, 0, 'l'},
  {"rcs", 0, 0, 'n'},
  {"show-c-function", 0, 0, 'p'},
  {"binary", 0, 0, 'q'},
  {"brief", 0, 0, 'q'},
  {"recursive", 0, 0, 'r'},
  {"report-identical-files", 0, 0, 's'},
  {"expand-tabs", 0, 0, 't'},
  {"ignore-all-space", 0, 0, 'w'},
  {"version", 0, 0, 'v'},
  {"extended-tests", 0, 0, 'X'},
  {0, 0, 0, 0}
};

main (argc, argv)
     int argc;
     char *argv[];
{
  int val;
  int c;
  int prev = -1;
  int longind;
  extern char *version_string;

  program = argv[0];

  /* Do our initializations. */
  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 = 0;
  function_regexp = 0;
  print_file_same_flag = FALSE;
  entire_new_file_flag = FALSE;
  no_details_flag = FALSE;
  quick_and_dirty = FALSE;
  context = -1;
  line_end_char = '\n';
  tab_align_flag = FALSE;
  tab_expand_flag = FALSE;
  recursive = FALSE;
  extended_tests = FALSE;
  paginate_flag = FALSE;
  ifdef_string = NULL;
  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:lnNpqQrsS:tTvwX",
			   longopts, &longind)) != EOF)
    {
      if (c == 0)		/* Long option. */
	c = longopts[longind].val;
      switch (c)
	{
	  /* All digits combine in decimal to specify the context-size.  */
	case '1':
	case '2':
	case '3':
	case '4':
	case '5':
	case '6':
	case '7':
	case '8':
	case '9':
	case '0':
	  if (context == -1)
	    context = 0;
	  /* If a context length has already been specified,
	     more digits allowed only if they follow right after the others.
	     Reject two separate runs of digits, or digits after -C.  */
	  else if (prev < '0' || prev > '9')
	    fatal ("context length specified twice");

	  context = context * 10 + c - '0';
	  break;

	case 'a':
	  /* Treat all files as text files; never treat as binary.  */
	  always_text_flag = 1;
	  break;

	case 'b':
	  /* Ignore changes in amount of whitespace.  */
	  ignore_space_change_flag = 1;
	  length_varies = 1;
	  break;

	case 'B':
	  /* Ignore changes affecting only blank lines.  */
	  ignore_blank_lines_flag = 1;
	  break;

	case 'C':
	case 129:		/* +context[=lines] */
	  if (optarg)
	    {
	      if (context >= 0)
		fatal ("context length specified twice");
	      {
		char *p;
		for (p = optarg; *p; p++)
		  if (*p < '0' || *p > '9')
		    fatal ("invalid context length argument");
	      }
	      context = atoi (optarg);
	    }

	  /* Falls through.  */
	case 'c':
	  /* Make context-style output.  */
	  specify_style (OUTPUT_CONTEXT);
	  break;

	case 'd':
	  /* Don't discard lines.  This makes things slower (sometimes much
	     slower) but will find a guaranteed minimal set of changes.  */
	  no_discards = 1;
	  break;

	case 'D':
	  /* Make merged #ifdef output.  */
	  specify_style (OUTPUT_IFDEF);
	  ifdef_string = optarg;
	  break;

	case 'e':
	  /* Make output that is a valid `ed' script.  */
	  specify_style (OUTPUT_ED);
	  break;

	case 'f':
	  /* Make output that looks vaguely like an `ed' script
	     but has changes in the order they appear in the file.  */
	  specify_style (OUTPUT_FORWARD_ED);
	  break;

	case 'F':
	  /* Show, for each set of changes, the previous line that
	     matches the specified regexp.  Currently affects only
	     context-style output.  */
	  function_regexp = optarg;
	  break;

	case 'h':
	  /* Split the files into chunks of around 1500 lines
	     for faster processing.  Usually does not change the result.

	     This currently has no effect.  */
	  break;

	case 'H':
	  /* Turn on heuristics that speed processing of large files
	     with a small density of changes.  */
	  heuristic = 1;
	  break;

	case 'i':
	  /* Ignore changes in case.  */
	  ignore_case_flag = 1;
	  break;

	case 'I':
	  /* Ignore changes affecting only lines that match the
	     specified regexp.  */
	  ignore_regexp = optarg;
	  break;

	case 'l':
	  /* Pass the output through `pr' to paginate it.  */
	  paginate_flag = 1;
	  break;

	case 'n':
	  /* Output RCS-style diffs, like `-f' except that each command
	     specifies the number of lines affected.  */
	  specify_style (OUTPUT_RCS);
	  break;

	case 'N':
	  /* When comparing directories, if a file appears only in one
	     directory, treat it as present but empty in the other.  */
	  entire_new_file_flag = 1;
	  break;

	case 'p':
	  /* Make context-style output and show name of last C function.  */
	  specify_style (OUTPUT_CONTEXT);
	  function_regexp = "^[_a-zA-Z]";
	  break;

	case 'q':
	  no_details_flag = 1;
	  break;

	case 'Q':
	  quick_and_dirty = 1;
	  no_details_flag = 1;
	  break;

	case 'r':
	  /* When comparing directories, 
	     recursively compare any subdirectories found.  */
	  recursive = 1;
	  break;

	case 's':
	  /* Print a message if the files are the same.  */
	  print_file_same_flag = 1;
	  break;

	case 'S':
	  /* When comparing directories, start with the specified
	     file name.  This is used for resuming an aborted comparison.  */
	  dir_start_file = optarg;
	  break;

	case 't':
	  /* Expand tabs to spaces in the output so that it preserves
	     the alignment of the input files.  */
	  tab_expand_flag = 1;
	  break;

	case 'T':
	  /* Use a tab in the output, rather than a space, before the
	     text of an input line, so as to keep the proper alignment
	     in the input line without changing the characters in it.  */
	  tab_align_flag = 1;
	  break;

	case 'v':
	  printf ("GNU diff version %s\n", version_string);
	  break;

	case 'w':
	  /* Ignore horizontal whitespace when comparing lines.  */
	  ignore_all_space_flag = 1;
	  length_varies = 1;
	  break;

	case 'X':
	  /* Do extended tests. */
	  extended_tests = 1;
	  break;

	default:
	  usage ();
	}
      prev = c;
    }

  if (optind != argc - 2)
    usage ();

  if (ignore_regexp)
    {
      char *val;
      bzero (&ignore_regexp_compiled, sizeof ignore_regexp_compiled);
      val = re_compile_pattern (ignore_regexp, strlen (ignore_regexp),
				&ignore_regexp_compiled);
      if (val != 0)
	error ("regexp to ignore: ", val);
      ignore_regexp_compiled.fastmap = (char *) xmalloc (256);
    }

  if (function_regexp)
    {
      char *val;
      bzero (&function_regexp_compiled, sizeof function_regexp_compiled);
      val = re_compile_pattern (function_regexp, strlen (function_regexp),
				&function_regexp_compiled);
      if (val != 0)
	error ("regexp for previous line: ", val);
      function_regexp_compiled.fastmap = (char *) xmalloc (256);
    }

  if (output_style != OUTPUT_CONTEXT)
    context = 0;
  else if (context == -1)
    /* Default amount of context for -c.  */
    context = 3;

  switch_string = option_list (argv + 1, optind - 1);

  val = compare_files (0, argv[optind], 0, argv[optind + 1], 0);

  /* Print any messages that were saved up for last.  */
  print_message_queue ();

  exit (val);
}

usage ()
{
  fprintf (stderr, "\
Usage: diff [-#] [-abBcdefhHilnNprstTvwX] [-C lines] [-F regexp] [-I regexp]\n\
       [-S file] [-D symbol] [+ignore-blank-lines] [+context[=lines]]\n\
       [+ifdef symbol] [+show-function-line regexp] [+speed-large-files]\n");
  fprintf (stderr, "\
       [+ignore-matching-lines regexp] [+entire-new-file] [+initial-tab]\n\
       [+starting-file file] [+text] [+all-text] [+ascii] [+minimal]\n\
       [+ignore-space-change] [+ed] [+reversed-ed] [+ignore-case] [+print]\n");
  fprintf (stderr, "\
       [+rcs] [+show-c-function] [+binary] [+brief] [+recursive]\n\
       [+report-identical-files] [+expand-tabs] [+ignore-all-space]\n\
       [+version] path1 path2\n");
  exit (1);
} 

specify_style (style)
     enum output_style style;
{
  if (output_style != OUTPUT_NORMAL
      && output_style != style)
    error ("conflicting specifications of output style");
  output_style = style;
}

/* 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.)
   This is self-contained; it opens the files and closes them.

   Value is 0 if files are identical, 1 if different,
   2 if there is a problem opening them.  */

int
compare_files (dir0, name0, dir1, name1, depth)
     char *dir0, *dir1;
     char *name0, *name1;
     int depth;
{
  struct file_data inf[2];
  struct link_data links[2];
  register int i;
  int val;
  int errorcount = 0;
  int stat_result[2];

  /* 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 (! entire_new_file_flag && (name0 == 0 || name1 == 0))
    {
      char *name = name0 == 0 ? name1 : name0;
      char *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;
    }

  /* Mark any nonexistent file with -1 in the desc field.  */

  inf[0].desc = name0 == 0 ? -1 : 0;
  inf[1].desc = name1 == 0 ? -1 : 0;

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

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

  inf[0].name = dir0 == 0 ? name0 : concat (dir0, "/", name0);
  inf[1].name = dir1 == 0 ? name1 : concat (dir1, "/", name1);

  /* Stat the files.  Record whether they are directories.
     Record in stat_result whether stat fails.  */

  for (i = 0; i <= 1; i++)
    {
      bzero (&inf[i].stat, sizeof(struct stat));
      inf[i].dir_p = 0;
      stat_result[i] = 0;

      if (inf[i].desc != -1
	  && strcmp (inf[i].name, "-"))
	{
	  char *filename = inf[i].name;

	  if (extended_tests) 
	    stat_result[i] = lstat (filename, &inf[i].stat);
	  else
	    stat_result[i] = stat (filename, &inf[i].stat);

	  if (stat_result[i] < 0)
	    {
	      perror_with_name (filename); 
	      errorcount = 1;
	    }
	  else
	    inf[i].dir_p = (S_IFDIR == (inf[i].stat.st_mode & S_IFMT));
	}
    }

  /* If we are doing extended tests, 
       ...check to see that the files are of the same type, if not, don't 
          bother with any other checks...
       ...check the nlinks field - if they aren't the same, then bitch 
          about it...
       ...compare uid, gid and modes...
       ...if they are both symlinks, compare the link values.  if they 
          aren't the same, don't bother with any other checks. */

  if (extended_tests) {
    if ((inf[0].stat.st_mode & S_IFMT) != (inf[1].stat.st_mode & S_IFMT)) {
      val = 1;
      message ("Files are of different types: %s and %s\n", 
	       inf[0].name, inf[1].name);
      goto done;
    }

    if (inf[0].stat.st_nlink != inf[1].stat.st_nlink) {
      message ("Files have different link counts: %s and %s\n",
	       inf[0].name, inf[1].name);
    }

    if (inf[0].stat.st_uid != inf[1].stat.st_uid) {
      message ("Files have different owners: %s and %s\n",
	       inf[0].name, inf[1].name);
    }

    if (inf[0].stat.st_gid != inf[1].stat.st_gid) {
      message ("Files have different groups: %s and %s\n",
	       inf[0].name, inf[1].name);
    }

    if ((inf[0].stat.st_mode & 07777) != (inf[1].stat.st_mode & 07777)) {
      message ("Files have different modes: %s and %s\n",
	       inf[0].name, inf[1].name);
    }

    /* FIFO or SOCKET - nothing to compare */
    if (((inf[0].stat.st_mode & S_IFMT) == S_IFIFO) ||
	((inf[0].stat.st_mode & S_IFMT) == S_IFSOCK)) {
      val = 0;
      goto done;
    }

    /* CHAR or BLOCK special device files - compare major and minor */
    /* device numbers... */
    if (((inf[0].stat.st_mode & S_IFMT) == S_IFCHR) || 
	((inf[0].stat.st_mode & S_IFMT) == S_IFBLK)) {
      if (inf[0].stat.st_rdev != inf[1].stat.st_rdev) {
	message ("Files have different device specs: %s and %s\n",
		 inf[0].name, inf[1].name);
	val = 1;
      } else {
	val = 0;
      }
      goto done;
    }

    if ((inf[0].stat.st_mode & S_IFMT) == S_IFLNK) {
      for (i = 0; i <= 1; i++) {
	links[i].size = readlink(inf[i].name, links[i].buf, LINKSIZE);
	if (links[i].size == -1) {
	  perror_with_name (inf[i].name);  
	  val = 2;
	  goto done;
	}
      }

      val = strncmp(links[0].buf, links[1].buf, 
		    min(links[0].size, links[1].size));
      if (val != 0) {
	val = 1;
	message ("Symlinks have different values: %s and %s\n",
		 inf[0].name, inf[1].name);
      }

      goto done;
    }
  }
	
  /* See if the two named files are actually the same physical file.
     If so, we know they are identical without actually reading them.  */

  if (inf[0].stat.st_ino == inf[1].stat.st_ino
      && inf[0].stat.st_dev == inf[1].stat.st_dev
      && stat_result[0] == 0
      && stat_result[1] == 0)
    {
      val = 0;
      goto done;
    }

  if (name0 == 0)
    inf[0].dir_p = inf[1].dir_p;
  if (name1 == 0)
    inf[1].dir_p = inf[0].dir_p;

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

  for (i = 0; i <= 1; i++)
    {
      if (inf[i].desc == -1)
	;
      else if (!strcmp (inf[i].name, "-"))
	{
	  inf[i].desc = 0;
	  inf[i].name = "Standard Input";
	}
      /* Don't bother opening if stat already failed.  */
      else if (stat_result[i] == 0 && ! inf[i].dir_p)
	{
	  char *filename = inf[i].name;

	  inf[i].desc = open (filename, O_RDONLY, 0);
	  if (0 > inf[i].desc)
	    {
	      perror_with_name (filename); 
	      errorcount = 1;
	    }
	}
    }

  if (errorcount)
    {

      /* If either file should exist but fails to be opened, return 2.  */

      val = 2;

    }
  else if (inf[0].dir_p && inf[1].dir_p)
    {
      if (output_style == OUTPUT_IFDEF)
	fatal ("-D option not supported with directories");

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

      if (depth > 0 && !recursive)
	{
	  /* But don't compare dir contents one level down
	     unless -r was specified.  */
	  message ("Common subdirectories: %s and %s\n",
		   inf[0].name, inf[1].name);
	  val = 0;
	}
      else
	{
	  val = diff_dirs (inf[0].name, inf[1].name, 
			   compare_files, depth, 0, 0);
	}

    }
  else if (depth == 0 && (inf[0].dir_p || inf[1].dir_p))
    {

      /* If only one is a directory, and it was specified in the command line,
	 use the file in that dir whose basename matches the other file.  */

      int dir_arg = (inf[0].dir_p ? 0 : 1);
      int fnm_arg = (inf[0].dir_p ? 1 : 0);
      char *p = rindex (inf[fnm_arg].name, '/');
      char *filename = concat (inf[dir_arg].name,  "/",
			       (p ? p+1 : inf[fnm_arg].name));

      inf[dir_arg].desc = open (filename, O_RDONLY, 0);

      if (0 > inf[dir_arg].desc)
	{
	  perror_with_name (filename); 
	  val = 2;
	}
      else
	{
	  /* JF: patch from the net to check and make sure we can really free
	     this.  If it's from argv[], freeing it is a *really* bad idea */
	  if (0 != (dir_arg ? dir1 : dir0))
	    free (inf[dir_arg].name);
	  inf[dir_arg].name = filename;
	  if (fstat (inf[dir_arg].desc, &inf[dir_arg].stat) < 0)
	    pfatal_with_name (inf[dir_arg].name);

	  inf[dir_arg].dir_p
	    = (S_IFDIR == (inf[dir_arg].stat.st_mode & S_IFMT));
	  if (inf[dir_arg].dir_p)
	    {
	      error ("%s is a directory but %s is not",
		     inf[dir_arg].name, inf[fnm_arg].name);
	      val = 1;
	    }
	  else 
	    val = diff_2_files (inf, depth);
	}

    }
  else if (depth > 0 && (inf[0].dir_p || inf[1].dir_p))
    {
      /* 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 (entire_new_file_flag && recursive)
	    val = diff_dirs (inf[0].name, inf[1].name, compare_files, depth,
			     inf[0].desc == -1, inf[1].desc == -1);
	  else
	    {
	      char *dir = (inf[0].desc == -1) ? dir1 : dir0;
	      message ("Only in %s: %s\n", dir, name0);
	      val = 1;
	    }
	}
      else
	{
	  /* We have a subdirectory in one directory
	     and a file in the other.  */

	  if (inf[0].dir_p)
	    message ("%s is a directory but %s is not\n",
		     inf[0].name, inf[1].name);
	  else
	    message ("%s is a directory but %s is not\n",
		     inf[1].name, inf[0].name);
	  /* This is a difference.  */
	  val = 1;
	}
    }
  else
    {

      /* Both exist and both are ordinary files.  */

      val = diff_2_files (inf, depth);

    }

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

  if (inf[0].desc > 0)
    close (inf[0].desc);
  if (inf[1].desc > 0)
    close (inf[1].desc);

 done:
  if (val == 0 && !inf[0].dir_p)
    {
      if (print_file_same_flag)
	message ("Files %s and %s are identical\n",
		 inf[0].name, inf[1].name);
    }
  else
    fflush (stdout);

  if (dir0 != 0)
    free (inf[0].name);
  if (dir1 != 0)
    free (inf[1].name);

  return val;
}
