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/* patch - a program to apply diffs to original files */

/* $Id: patch.c,v 1.23 1997/07/05 10:32:23 eggert Exp $ */

/*
Copyright 1984, 1985, 1986, 1987, 1988 Larry Wall
Copyright 1989, 1990, 1991, 1992, 1993, 1997 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; see the file COPYING.
If not, write to the Free Software Foundation,
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

#define XTERN
#include <common.h>
#undef XTERN
#define XTERN extern
#include <argmatch.h>
#include <backupfile.h>
#include <getopt.h>
#include <inp.h>
#include <pch.h>
#include <util.h>
#include <version.h>

#if HAVE_UTIME_H
# include <utime.h>
#endif
/* Some nonstandard hosts don't declare this structure even in <utime.h>.  */
#if ! HAVE_STRUCT_UTIMBUF
struct utimbuf
{
  time_t actime;
  time_t modtime;
};
#endif

/* Output stream state.  */
struct outstate
{
  FILE *ofp;
  int after_newline;
  int zero_output;
};

/* procedures */

static FILE *create_output_file PARAMS ((char const *));
static LINENUM locate_hunk PARAMS ((LINENUM));
static bool apply_hunk PARAMS ((struct outstate *, LINENUM));
static bool copy_till PARAMS ((struct outstate *, LINENUM));
static bool patch_match PARAMS ((LINENUM, LINENUM, LINENUM, LINENUM));
static bool similar PARAMS ((char const *, size_t, char const *, size_t));
static bool spew_output PARAMS ((struct outstate *));
static char const *make_temp PARAMS ((int));
static int numeric_string PARAMS ((char const *, int, char const *));
static void abort_hunk PARAMS ((void));
static void cleanup PARAMS ((void));
static void get_some_switches PARAMS ((void));
static void init_output PARAMS ((char const *, struct outstate *));
static void init_reject PARAMS ((char const *));
static void reinitialize_almost_everything PARAMS ((void));
static void usage PARAMS ((FILE *, int)) __attribute__((noreturn));

static int make_backups;
static int backup_if_mismatch;
static char const *version_control;
static int remove_empty_files;

/* TRUE if -R was specified on command line.  */
static int reverse_flag_specified;

/* how many input lines have been irretractably output */
static LINENUM last_frozen_line;

static char const *do_defines; /* symbol to patch using ifdef, ifndef, etc. */
static char const if_defined[] = "\n#ifdef %s\n";
static char const not_defined[] = "#ifndef %s\n";
static char const else_defined[] = "\n#else\n";
static char const end_defined[] = "\n#endif /* %s */\n";

static int Argc;
static char * const *Argv;

static FILE *rejfp;  /* reject file pointer */

static char const *patchname;
static char *rejname;
static char const * volatile TMPREJNAME;

static LINENUM last_offset;
static LINENUM maxfuzz = 2;

static char serrbuf[BUFSIZ];

char const program_name[] = "patch";

/* Apply a set of diffs as appropriate. */

int main PARAMS ((int, char **));

int
main(argc,argv)
int argc;
char **argv;
{
    char const *val;
    bool somefailed = FALSE;
    struct outstate outstate;

    init_time ();

    setbuf(stderr, serrbuf);

    bufsize = 8 * 1024;
    buf = xmalloc (bufsize);

    strippath = INT_MAX;

    posixly_correct = getenv ("POSIXLY_CORRECT") != 0;
    backup_if_mismatch = ! posixly_correct;
    patch_get = ((val = getenv ("PATCH_GET"))
                 ? numeric_string (val, 1, "PATCH_GET value")
                 : posixly_correct - 1);

    {
      char const *v = getenv ("SIMPLE_BACKUP_SUFFIX");
      if (v && *v)
        simple_backup_suffix = v;
    }

    version_control = getenv ("PATCH_VERSION_CONTROL");
    if (! version_control)
      version_control = getenv ("VERSION_CONTROL");

    /* Cons up the names of the global temporary files.
       Do this before `cleanup' can possibly be called (e.g. by `pfatal').  */
    TMPOUTNAME = make_temp ('o');
    TMPINNAME = make_temp ('i');
    TMPREJNAME = make_temp ('r');
    TMPPATNAME = make_temp ('p');

    /* parse switches */
    Argc = argc;
    Argv = argv;
    get_some_switches();

    if (make_backups | backup_if_mismatch)
      backup_type = get_version (version_control);

    init_output (outfile, &outstate);

    /* Make sure we clean up in case of disaster.  */
    set_signals(0);

    for (
        open_patch_file (patchname);
        there_is_another_patch();
        reinitialize_almost_everything()
    ) {                                 /* for each patch in patch file */
      int hunk = 0;
      int failed = 0;
      int mismatch = 0;
      char *outname = outfile ? outfile : inname;

      if (!skip_rest_of_patch)
        get_input_file (inname, outname);

      if (diff_type == ED_DIFF) {
        outstate.zero_output = 0;
        if (! dry_run)
          {
            do_ed_script (outstate.ofp);
            if (! outfile)
              {
                struct stat statbuf;
                if (stat (TMPOUTNAME, &statbuf) != 0)
                  pfatal ("%s", TMPOUTNAME);
                outstate.zero_output = statbuf.st_size == 0;
              }
          }
      } else {
        int got_hunk;
        int apply_anyway = 0;

        /* initialize the patched file */
        if (! skip_rest_of_patch && ! outfile)
          init_output (TMPOUTNAME, &outstate);

        /* initialize reject file */
        init_reject(TMPREJNAME);

        /* find out where all the lines are */
        if (!skip_rest_of_patch)
            scan_input (inname);

        /* from here on, open no standard i/o files, because malloc */
        /* might misfire and we can't catch it easily */

        /* apply each hunk of patch */
        while (0 < (got_hunk = another_hunk (diff_type, reverse))) {
            LINENUM where = 0; /* Pacify `gcc -Wall'.  */
            LINENUM newwhere;
            LINENUM fuzz = 0;
            LINENUM prefix_context = pch_prefix_context ();
            LINENUM suffix_context = pch_suffix_context ();
            LINENUM context = (prefix_context < suffix_context
                               ? suffix_context : prefix_context);
            LINENUM mymaxfuzz = (maxfuzz < context ? maxfuzz : context);
            hunk++;
            if (!skip_rest_of_patch) {
                do {
                    where = locate_hunk(fuzz);
                    if (! where || fuzz || last_offset)
                      mismatch = 1;
                    if (hunk == 1 && ! where && ! (force | apply_anyway)
                        && reverse == reverse_flag_specified) {
                                                /* dwim for reversed patch? */
                        if (!pch_swap()) {
                            say (
"Not enough memory to try swapped hunk!  Assuming unswapped.\n");
                            continue;
                        }
                        /* Try again.  */
                        where = locate_hunk (fuzz);
                        if (where
                            && (ok_to_reverse
                                ("%s patch detected!",
                                 (reverse
                                  ? "Unreversed"
                                  : "Reversed (or previously applied)"))))
                          reverse ^= 1;
                        else
                          {
                            /* Put it back to normal.  */
                            if (! pch_swap ())
                              fatal ("lost hunk on alloc error!");
                            if (where)
                              {
                                apply_anyway = 1;
                                fuzz--; /* Undo `++fuzz' below.  */
                                where = 0;
                              }
                          }
                    }
                } while (!skip_rest_of_patch && !where
                         && ++fuzz <= mymaxfuzz);

                if (skip_rest_of_patch) {               /* just got decided */
                  if (outstate.ofp && ! outfile)
                    {
                      fclose (outstate.ofp);
                      outstate.ofp = 0;
                    }
                }
            }

            newwhere = pch_newfirst() + last_offset;
            if (skip_rest_of_patch) {
                abort_hunk();
                failed++;
                if (verbosity == VERBOSE)
                    say ("Hunk #%d ignored at %ld.\n", hunk, newwhere);
            }
            else if (!where
                     || (where == 1 && pch_says_nonexistent (reverse)
                         && instat.st_size)) {
                if (where)
                  say ("Patch attempted to create file `%s', which already exists.\n", inname);
                abort_hunk();
                failed++;
                if (verbosity != SILENT)
                    say ("Hunk #%d FAILED at %ld.\n", hunk, newwhere);
            }
            else if (! apply_hunk (&outstate, where)) {
                abort_hunk ();
                failed++;
                if (verbosity != SILENT)
                    say ("Hunk #%d FAILED at %ld.\n", hunk, newwhere);
            } else {
                if (verbosity == VERBOSE
                    || (verbosity != SILENT && (fuzz || last_offset))) {
                    say ("Hunk #%d succeeded at %ld", hunk, newwhere);
                    if (fuzz)
                        say (" with fuzz %ld", fuzz);
                    if (last_offset)
                        say (" (offset %ld line%s)",
                            last_offset, last_offset==1?"":"s");
                    say (".\n");
                }
            }
        }

        if (got_hunk < 0  &&  using_plan_a) {
            if (outfile)
              fatal ("out of memory using Plan A");
            say ("\n\nRan out of memory using Plan A -- trying again...\n\n");
            if (outstate.ofp)
              {
                fclose (outstate.ofp);
                outstate.ofp = 0;
              }
            fclose (rejfp);
            continue;
        }

        /* finish spewing out the new file */
        if (!skip_rest_of_patch)
          {
            assert (hunk);
            if (! spew_output (&outstate))
              {
                say ("Skipping patch.\n");
                skip_rest_of_patch = TRUE;
              }
          }
      }

      /* and put the output where desired */
      ignore_signals ();
      if (! skip_rest_of_patch && ! outfile) {
          if (outstate.zero_output
              && (remove_empty_files
                  || (pch_says_nonexistent (reverse ^ 1) == 2
                      && ! posixly_correct)))
            {
              if (verbosity == VERBOSE)
                say ("Removing file `%s'%s.\n", outname,
                     dry_run ? " and any empty ancestor directories" : "");
              if (! dry_run)
                {
                  move_file ((char *) 0, outname, (mode_t) 0,
                             (make_backups
                              || (backup_if_mismatch && (mismatch | failed))));
                  removedirs (outname);
                }
            }
          else
            {
              if (! outstate.zero_output
                  && pch_says_nonexistent (reverse ^ 1))
                {
                  mismatch = 1;
                  if (verbosity != SILENT)
                    say ("File `%s' is not empty after patch, as expected.\n",
                         outname);
                }

              if (! dry_run)
                {
                  time_t t;

                  move_file (TMPOUTNAME, outname, instat.st_mode,
                             (make_backups
                              || (backup_if_mismatch && (mismatch | failed))));

                  if ((set_time | set_utc)
                      && (t = pch_timestamp (reverse ^ 1)) != (time_t) -1)
                    {
                      struct utimbuf utimbuf;
                      utimbuf.actime = utimbuf.modtime = t;

                      if (! force && ! inerrno
                          && ! pch_says_nonexistent (reverse)
                          && (t = pch_timestamp (reverse)) != (time_t) -1
                          && t != instat.st_mtime)
                        say ("not setting time of file `%s' (time mismatch)\n",
                             outname);
                      else if (! force && (mismatch | failed))
                        say ("not setting time of file `%s' (contents mismatch)\n",
                             outname);
                      else if (utime (outname, &utimbuf) != 0)
                        pfatal ("can't set timestamp on file `%s'", outname);
                    }

                  if (! inerrno && chmod (outname, instat.st_mode) != 0)
                    pfatal ("can't set permissions on file `%s'", outname);
                }
            }
      }
      if (diff_type != ED_DIFF) {
        if (fclose (rejfp) != 0)
            write_fatal ();
        if (failed) {
            somefailed = TRUE;
            say ("%d out of %d hunk%s %s", failed, hunk, "s" + (hunk == 1),
                 skip_rest_of_patch ? "ignored" : "FAILED");
            if (outname) {
                char *rej = rejname;
                if (!rejname) {
                    rej = xmalloc (strlen (outname) + 5);
                    strcpy (rej, outname);
                    addext (rej, ".rej", '#');
                }
                say (" -- saving rejects to %s", rej);
                if (! dry_run)
                  {
                    move_file (TMPREJNAME, rej, instat.st_mode, FALSE);
                    if (! inerrno
                        && (chmod (rej, (instat.st_mode
                                         & ~(S_IXUSR|S_IXGRP|S_IXOTH)))
                            != 0))
                      pfatal ("can't set permissions on file `%s'", rej);
                  }
                if (!rejname)
                    free (rej);
            }
            say ("\n");
        }
      }
      set_signals (1);
    }
    if (outstate.ofp && (ferror (outstate.ofp) || fclose (outstate.ofp) != 0))
      write_fatal ();
    cleanup ();
    if (somefailed)
      exit (1);
    return 0;
}

/* Prepare to find the next patch to do in the patch file. */

static void
reinitialize_almost_everything()
{
    re_patch();
    re_input();

    input_lines = 0;
    last_frozen_line = 0;

    if (inname) {
        free (inname);
        inname = 0;
    }

    last_offset = 0;

    diff_type = NO_DIFF;

    if (revision) {
        free(revision);
        revision = 0;
    }

    reverse = reverse_flag_specified;
    skip_rest_of_patch = FALSE;
}

static char const shortopts[] = "bB:cd:D:eEfF:g:i:lnNo:p:r:RstTuvV:x:Y:z:Z";
static struct option const longopts[] =
{
  {"backup", no_argument, NULL, 'b'},
  {"prefix", required_argument, NULL, 'B'},
  {"context", no_argument, NULL, 'c'},
  {"directory", required_argument, NULL, 'd'},
  {"ifdef", required_argument, NULL, 'D'},
  {"ed", no_argument, NULL, 'e'},
  {"remove-empty-files", no_argument, NULL, 'E'},
  {"force", no_argument, NULL, 'f'},
  {"fuzz", required_argument, NULL, 'F'},
  {"get", no_argument, NULL, 'g'},
  {"input", required_argument, NULL, 'i'},
  {"ignore-whitespace", no_argument, NULL, 'l'},
  {"normal", no_argument, NULL, 'n'},
  {"forward", no_argument, NULL, 'N'},
  {"output", required_argument, NULL, 'o'},
  {"strip", required_argument, NULL, 'p'},
  {"reject-file", required_argument, NULL, 'r'},
  {"reverse", no_argument, NULL, 'R'},
  {"quiet", no_argument, NULL, 's'},
  {"silent", no_argument, NULL, 's'},
  {"batch", no_argument, NULL, 't'},
  {"set-time", no_argument, NULL, 'T'},
  {"unified", no_argument, NULL, 'u'},
  {"version", no_argument, NULL, 'v'},
  {"version-control", required_argument, NULL, 'V'},
  {"debug", required_argument, NULL, 'x'},
  {"basename-prefix", required_argument, NULL, 'Y'},
  {"suffix", required_argument, NULL, 'z'},
  {"set-utc", no_argument, NULL, 'Z'},
  {"dry-run", no_argument, NULL, 129},
  {"verbose", no_argument, NULL, 130},
  {"binary", no_argument, NULL, 131},
  {"help", no_argument, NULL, 132},
  {"backup-if-mismatch", no_argument, NULL, 133},
  {"no-backup-if-mismatch", no_argument, NULL, 134},
  {NULL, no_argument, NULL, 0}
};

static char const *const option_help[] =
{
"Input options:",
"",
"  -p NUM  --strip=NUM  Strip NUM leading components from file names.",
"  -F LINES  --fuzz LINES  Set the fuzz factor to LINES for inexact matching.",
"  -l  --ignore-whitespace  Ignore white space changes between patch and input.",
"",
"  -c  --context  Interpret the patch as a context difference.",
"  -e  --ed  Interpret the patch as an ed script.",
"  -n  --normal  Interpret the patch as a normal difference.",
"  -u  --unified  Interpret the patch as a unified difference.",
"",
"  -N  --forward  Ignore patches that appear to be reversed or already applied.",
"  -R  --reverse  Assume patches were created with old and new files swapped.",
"",
"  -i PATCHFILE  --input=PATCHFILE  Read patch from PATCHFILE instead of stdin.",
"",
"Output options:",
"",
"  -o FILE  --output=FILE  Output patched files to FILE.",
"  -r FILE  --reject-file=FILE  Output rejects to FILE.",
"",
"  -D NAME  --ifdef=NAME  Make merged if-then-else output using NAME.",
"  -E  --remove-empty-files  Remove output files that are empty after patching.",
"",
"  -Z  --set-utc  Set times of patched files, assuming diff uses UTC (GMT).",
"  -T  --set-time  Likewise, assuming local time.",
"",
"Backup and version control options:",
"",
"  -b  --backup  Back up the original contents of each file.",
"  --backup-if-mismatch  Back up if the patch does not match exactly.",
"  --no-backup-if-mismatch  Back up mismatches only if otherwise requested.",
"",
"  -V STYLE  --version-control=STYLE  Use STYLE version control.",
"       STYLE is either 'simple', 'numbered', or 'existing'.",
"  -B PREFIX  --prefix=PREFIX  Prepend PREFIX to backup file names.",
"  -Y PREFIX  --basename-prefix=PREFIX  Prepend PREFIX to backup file basenames.",
"  -z SUFFIX  --suffix=SUFFIX  Append SUFFIX to backup file names.",
"",
"  -g NUM  --get=NUM  Get files from RCS or SCCS if positive; ask if negative.",
"",
"Miscellaneous options:",
"",
"  -t  --batch  Ask no questions; skip bad-Prereq patches; assume reversed.",
"  -f  --force  Like -t, but ignore bad-Prereq patches, and assume unreversed.",
"  -s  --quiet  --silent  Work silently unless an error occurs.",
"  --verbose  Output extra information about the work being done.",
"  --dry-run  Do not actually change any files; just print what would happen.",
"",
"  -d DIR  --directory=DIR  Change the working directory to DIR first.",
#if HAVE_SETMODE
"  --binary  Read and write data in binary mode.",
#else
"  --binary  Read and write data in binary mode (no effect on this platform).",
#endif
"",
"  -v  --version  Output version info.",
"  --help  Output this help.",
"",
"Report bugs to <bug-gnu-utils@prep.ai.mit.edu>.",
0
};

static void
usage (stream, status)
     FILE *stream;
     int status;
{
  char const * const *p;

  if (status != 0)
    {
      fprintf (stream, "%s: Try `%s --help' for more information.\n",
               program_name, Argv[0]);
    }
  else
    {
      fprintf (stream, "Usage: %s [OPTION]... [ORIGFILE [PATCHFILE]]\n\n",
               Argv[0]);
      for (p = option_help;  *p;  p++)
        fprintf (stream, "%s\n", *p);
    }

  exit (status);
}

/* Process switches and filenames.  */

static void
get_some_switches()
{
    register int optc;

    if (rejname)
        free (rejname);
    rejname = 0;
    if (optind == Argc)
        return;
    while ((optc = getopt_long (Argc, Argv, shortopts, longopts, (int *) 0))
           != -1) {
        switch (optc) {
            case 'b':
                make_backups = 1;
                 /* Special hack for backward compatibility with CVS 1.9.
                    If the last 4 args are `-b SUFFIX ORIGFILE PATCHFILE',
                    treat `-b' as if it were `-b -z'.  */
                if (Argc - optind == 3
                    && strcmp (Argv[optind - 1], "-b") == 0
                    && ! (Argv[optind + 0][0] == '-' && Argv[optind + 0][1])
                    && ! (Argv[optind + 1][0] == '-' && Argv[optind + 1][1])
                    && ! (Argv[optind + 2][0] == '-' && Argv[optind + 2][1]))
                  {
                    optarg = Argv[optind++];
                    if (verbosity != SILENT)
                      say ("warning: the `-b %s' option is obsolete; use `-b -z %s' instead\n",
                           optarg, optarg);
                    goto case_z;
                  }
                break;
            case 'B':
                if (!*optarg)
                  fatal ("backup prefix is empty");
                origprae = savestr (optarg);
                break;
            case 'c':
                diff_type = CONTEXT_DIFF;
                break;
            case 'd':
                if (chdir(optarg) < 0)
                  pfatal ("can't change directory to `%s'", optarg);
                break;
            case 'D':
                do_defines = savestr (optarg);
                break;
            case 'e':
                diff_type = ED_DIFF;
                break;
            case 'E':
                remove_empty_files = TRUE;
                break;
            case 'f':
                force = TRUE;
                break;
            case 'F':
                maxfuzz = numeric_string (optarg, 0, "fuzz factor");
                break;
            case 'g':
                patch_get = numeric_string (optarg, 1, "get option value");
                break;
            case 'i':
                patchname = savestr (optarg);
                break;
            case 'l':
                canonicalize = TRUE;
                break;
            case 'n':
                diff_type = NORMAL_DIFF;
                break;
            case 'N':
                noreverse = TRUE;
                break;
            case 'o':
                if (strcmp (optarg, "-") == 0)
                  fatal ("can't output patches to standard output");
                outfile = savestr (optarg);
                break;
            case 'p':
                strippath = numeric_string (optarg, 0, "strip count");
                break;
            case 'r':
                rejname = savestr (optarg);
                break;
            case 'R':
                reverse = 1;
                reverse_flag_specified = 1;
                break;
            case 's':
                verbosity = SILENT;
                break;
            case 't':
                batch = TRUE;
                break;
            case 'T':
                set_time = 1;
                break;
            case 'u':
                diff_type = UNI_DIFF;
                break;
            case 'v':
                version();
                exit (0);
                break;
            case 'V':
                version_control = optarg;
                break;
#if DEBUGGING
            case 'x':
                debug = numeric_string (optarg, 1, "debugging option");
                break;
#endif
            case 'Y':
                if (!*optarg)
                  fatal ("backup basename prefix is empty");
                origbase = savestr (optarg);
                break;
            case 'z':
            case_z:
                if (!*optarg)
                  fatal ("backup suffix is empty");
                simple_backup_suffix = savestr (optarg);
                break;
            case 'Z':
                set_utc = 1;
                break;
            case 129:
                dry_run = TRUE;
                break;
            case 130:
                verbosity = VERBOSE;
                break;
            case 131:
#if HAVE_SETMODE
                binary_transput = O_BINARY;
#endif
                break;
            case 132:
                usage (stdout, 0);
            case 133:
                backup_if_mismatch = 1;
                break;
            case 134:
                backup_if_mismatch = 0;
                break;
            default:
                usage (stderr, 2);
        }
    }

    /* Process any filename args.  */
    if (optind < Argc)
      {
        inname = savestr (Argv[optind++]);
        invc = -1;
        if (optind < Argc)
          {
            patchname = savestr (Argv[optind++]);
            if (optind < Argc)
              {
                fprintf (stderr, "%s: extra operand `%s'\n",
                         program_name, Argv[optind]);
                usage (stderr, 2);
              }
          }
      }
}

/* Handle STRING (possibly negative if NEGATIVE_ALLOWED is nonzero)
   of type ARGTYPE_MSGID by converting it to an integer,
   returning the result.  */
static int
numeric_string (string, negative_allowed, argtype_msgid)
     char const *string;
     int negative_allowed;
     char const *argtype_msgid;
{
  int value = 0;
  char const *p = string;
  int sign = *p == '-' ? -1 : 1;

  p += *p == '-' || *p == '+';

  do
    {
      int v10 = value * 10;
      int digit = *p - '0';
      int signed_digit = sign * digit;
      int next_value = v10 + signed_digit;

      if (9 < (unsigned) digit)
        fatal ("%s `%s' is not a number", argtype_msgid, string);

      if (v10 / 10 != value || (next_value < v10) != (signed_digit < 0))
        fatal ("%s `%s' is too large", argtype_msgid, string);

      value = next_value;
    }
  while (*++p);

  if (value < 0 && ! negative_allowed)
    fatal ("%s `%s' is negative", argtype_msgid, string);

  return value;
}

/* Attempt to find the right place to apply this hunk of patch. */

static LINENUM
locate_hunk(fuzz)
LINENUM fuzz;
{
    register LINENUM first_guess = pch_first () + last_offset;
    register LINENUM offset;
    LINENUM pat_lines = pch_ptrn_lines();
    LINENUM prefix_context = pch_prefix_context ();
    LINENUM suffix_context = pch_suffix_context ();
    LINENUM context = (prefix_context < suffix_context
                       ? suffix_context : prefix_context);
    LINENUM prefix_fuzz = fuzz + prefix_context - context;
    LINENUM suffix_fuzz = fuzz + suffix_context - context;
    LINENUM max_where = input_lines - (pat_lines - suffix_fuzz) + 1;
    LINENUM min_where = last_frozen_line + 1 - (prefix_context - prefix_fuzz);
    LINENUM max_pos_offset = max_where - first_guess;
    LINENUM max_neg_offset = first_guess - min_where;
    LINENUM max_offset = (max_pos_offset < max_neg_offset
                          ? max_neg_offset : max_pos_offset);

    if (!pat_lines)                     /* null range matches always */
        return first_guess;

    /* Do not try lines <= 0.  */
    if (first_guess <= max_neg_offset)
        max_neg_offset = first_guess - 1;

    if (prefix_fuzz < 0)
      {
        /* Can only match start of file.  */

        if (suffix_fuzz < 0)
          /* Can only match entire file.  */
          if (pat_lines != input_lines || prefix_context < last_frozen_line)
            return 0;

        offset = 1 - first_guess;
        if (last_frozen_line <= prefix_context
            && offset <= max_pos_offset
            && patch_match (first_guess, offset, (LINENUM) 0, suffix_fuzz))
          {
            last_offset = offset;
            return first_guess + offset;
          }
        else
          return 0;
      }

    if (suffix_fuzz < 0)
      {
        /* Can only match end of file.  */
        offset = first_guess - (input_lines - pat_lines + 1);
        if (offset <= max_neg_offset
            && patch_match (first_guess, -offset, prefix_fuzz, (LINENUM) 0))
          {
            last_offset = - offset;
            return first_guess - offset;
          }
        else
          return 0;
      }

    for (offset = 0;  offset <= max_offset;  offset++) {
        if (offset <= max_pos_offset
            && patch_match (first_guess, offset, prefix_fuzz, suffix_fuzz)) {
            if (debug & 1)
                say ("Offset changing from %ld to %ld\n", last_offset, offset);
            last_offset = offset;
            return first_guess+offset;
        }
        if (0 < offset && offset <= max_neg_offset
            && patch_match (first_guess, -offset, prefix_fuzz, suffix_fuzz)) {
            if (debug & 1)
                say ("Offset changing from %ld to %ld\n", last_offset, -offset);
            last_offset = -offset;
            return first_guess-offset;
        }
    }
    return 0;
}

/* We did not find the pattern, dump out the hunk so they can handle it. */

static void
abort_hunk()
{
    register LINENUM i;
    register LINENUM pat_end = pch_end ();
    /* add in last_offset to guess the same as the previous successful hunk */
    LINENUM oldfirst = pch_first() + last_offset;
    LINENUM newfirst = pch_newfirst() + last_offset;
    LINENUM oldlast = oldfirst + pch_ptrn_lines() - 1;
    LINENUM newlast = newfirst + pch_repl_lines() - 1;
    char const *stars =
      (int) NEW_CONTEXT_DIFF <= (int) diff_type ? " ****" : "";
    char const *minuses =
      (int) NEW_CONTEXT_DIFF <= (int) diff_type ? " ----" : " -----";

    fprintf(rejfp, "***************\n");
    for (i=0; i<=pat_end; i++) {
        switch (pch_char(i)) {
        case '*':
            if (oldlast < oldfirst)
                fprintf(rejfp, "*** 0%s\n", stars);
            else if (oldlast == oldfirst)
                fprintf(rejfp, "*** %ld%s\n", oldfirst, stars);
            else
                fprintf(rejfp, "*** %ld,%ld%s\n", oldfirst, oldlast, stars);
            break;
        case '=':
            if (newlast < newfirst)
                fprintf(rejfp, "--- 0%s\n", minuses);
            else if (newlast == newfirst)
                fprintf(rejfp, "--- %ld%s\n", newfirst, minuses);
            else
                fprintf(rejfp, "--- %ld,%ld%s\n", newfirst, newlast, minuses);
            break;
        case ' ': case '-': case '+': case '!':
            fprintf (rejfp, "%c ", pch_char (i));
            /* fall into */
        case '\n':
            pch_write_line (i, rejfp);
            break;
        default:
            fatal ("fatal internal error in abort_hunk");
        }
        if (ferror (rejfp))
          write_fatal ();
    }
}

/* We found where to apply it (we hope), so do it. */

static bool
apply_hunk (outstate, where)
     struct outstate *outstate;
     LINENUM where;
{
    register LINENUM old = 1;
    register LINENUM lastline = pch_ptrn_lines ();
    register LINENUM new = lastline+1;
    register enum {OUTSIDE, IN_IFNDEF, IN_IFDEF, IN_ELSE} def_state = OUTSIDE;
    register char const *R_do_defines = do_defines;
    register LINENUM pat_end = pch_end ();
    register FILE *fp = outstate->ofp;

    where--;
    while (pch_char(new) == '=' || pch_char(new) == '\n')
        new++;

    while (old <= lastline) {
        if (pch_char(old) == '-') {
            assert (outstate->after_newline);
            if (! copy_till (outstate, where + old - 1))
                return FALSE;
            if (R_do_defines) {
                if (def_state == OUTSIDE) {
                    fprintf (fp, outstate->after_newline + if_defined,
                             R_do_defines);
                    def_state = IN_IFNDEF;
                }
                else if (def_state == IN_IFDEF) {
                    fprintf (fp, outstate->after_newline + else_defined);
                    def_state = IN_ELSE;
                }
                if (ferror (fp))
                  write_fatal ();
                outstate->after_newline = pch_write_line (old, fp);
                outstate->zero_output = 0;
            }
            last_frozen_line++;
            old++;
        }
        else if (new > pat_end) {
            break;
        }
        else if (pch_char(new) == '+') {
            if (! copy_till (outstate, where + old - 1))
                return FALSE;
            if (R_do_defines) {
                if (def_state == IN_IFNDEF) {
                    fprintf (fp, outstate->after_newline + else_defined);
                    def_state = IN_ELSE;
                }
                else if (def_state == OUTSIDE) {
                    fprintf (fp, outstate->after_newline + if_defined,
                             R_do_defines);
                    def_state = IN_IFDEF;
                }
                if (ferror (fp))
                  write_fatal ();
            }
            outstate->after_newline = pch_write_line (new, fp);
            outstate->zero_output = 0;
            new++;
        }
        else if (pch_char(new) != pch_char(old)) {
            if (debug & 1)
              say ("oldchar = '%c', newchar = '%c'\n",
                   pch_char (old), pch_char (new));
            fatal ("Out-of-sync patch, lines %ld,%ld -- mangled text or line numbers, maybe?",
                pch_hunk_beg() + old,
                pch_hunk_beg() + new);
        }
        else if (pch_char(new) == '!') {
            assert (outstate->after_newline);
            if (! copy_till (outstate, where + old - 1))
                return FALSE;
            assert (outstate->after_newline);
            if (R_do_defines) {
               fprintf (fp, not_defined, R_do_defines);
               if (ferror (fp))
                write_fatal ();
               def_state = IN_IFNDEF;
            }

            do
              {
                if (R_do_defines) {
                    outstate->after_newline = pch_write_line (old, fp);
                }
                last_frozen_line++;
                old++;
              }
            while (pch_char (old) == '!');

            if (R_do_defines) {
                fprintf (fp, outstate->after_newline + else_defined);
                if (ferror (fp))
                  write_fatal ();
                def_state = IN_ELSE;
            }

            do
              {
                outstate->after_newline = pch_write_line (new, fp);
                new++;
              }
            while (pch_char (new) == '!');
            outstate->zero_output = 0;
        }
        else {
            assert(pch_char(new) == ' ');
            old++;
            new++;
            if (R_do_defines && def_state != OUTSIDE) {
                fprintf (fp, outstate->after_newline + end_defined,
                         R_do_defines);
                if (ferror (fp))
                  write_fatal ();
                outstate->after_newline = 1;
                def_state = OUTSIDE;
            }
        }
    }
    if (new <= pat_end && pch_char(new) == '+') {
        if (! copy_till (outstate, where + old - 1))
            return FALSE;
        if (R_do_defines) {
            if (def_state == OUTSIDE) {
                fprintf (fp, outstate->after_newline + if_defined,
                         R_do_defines);
                def_state = IN_IFDEF;
            }
            else if (def_state == IN_IFNDEF) {
                fprintf (fp, outstate->after_newline + else_defined);
                def_state = IN_ELSE;
            }
            if (ferror (fp))
              write_fatal ();
            outstate->zero_output = 0;
        }

        do
          {
            if (! outstate->after_newline  &&  putc ('\n', fp) == EOF)
              write_fatal ();
            outstate->after_newline = pch_write_line (new, fp);
            outstate->zero_output = 0;
            new++;
          }
        while (new <= pat_end && pch_char (new) == '+');
    }
    if (R_do_defines && def_state != OUTSIDE) {
        fprintf (fp, outstate->after_newline + end_defined, R_do_defines);
        if (ferror (fp))
          write_fatal ();
        outstate->after_newline = 1;
    }
    return TRUE;
}

/* Create an output file.  */

static FILE *
create_output_file (name)
     char const *name;
{
  int fd = create_file (name, O_WRONLY | binary_transput, instat.st_mode);
  FILE *f = fdopen (fd, binary_transput ? "wb" : "w");
  if (! f)
    pfatal ("can't create `%s'", name);
  return f;
}

/* Open the new file. */

static void
init_output (name, outstate)
     char const *name;
     struct outstate *outstate;
{
  outstate->ofp = name ? create_output_file (name) : (FILE *) 0;
  outstate->after_newline = 1;
  outstate->zero_output = 1;
}

/* Open a file to put hunks we can't locate. */

static void
init_reject(name)
     char const *name;
{
  rejfp = create_output_file (name);
}

/* Copy input file to output, up to wherever hunk is to be applied. */

static bool
copy_till (outstate, lastline)
     register struct outstate *outstate;
     register LINENUM lastline;
{
    register LINENUM R_last_frozen_line = last_frozen_line;
    register FILE *fp = outstate->ofp;
    register char const *s;
    size_t size;

    if (R_last_frozen_line > lastline)
      {
        say ("misordered hunks! output would be garbled\n");
        return FALSE;
      }
    while (R_last_frozen_line < lastline)
      {
        s = ifetch (++R_last_frozen_line, 0, &size);
        if (size)
          {
            if ((! outstate->after_newline  &&  putc ('\n', fp) == EOF)
                || ! fwrite (s, sizeof *s, size, fp))
              write_fatal ();
            outstate->after_newline = s[size - 1] == '\n';
            outstate->zero_output = 0;
          }
      }
    last_frozen_line = R_last_frozen_line;
    return TRUE;
}

/* Finish copying the input file to the output file. */

static bool
spew_output (outstate)
     struct outstate *outstate;
{
    if (debug & 256)
      say ("il=%ld lfl=%ld\n", input_lines, last_frozen_line);

    if (last_frozen_line < input_lines)
      if (! copy_till (outstate, input_lines))
        return FALSE;

    if (outstate->ofp && ! outfile)
      {
        if (fclose (outstate->ofp) != 0)
          write_fatal ();
        outstate->ofp = 0;
      }

    return TRUE;
}

/* Does the patch pattern match at line base+offset? */

static bool
patch_match (base, offset, prefix_fuzz, suffix_fuzz)
LINENUM base;
LINENUM offset;
LINENUM prefix_fuzz;
LINENUM suffix_fuzz;
{
    register LINENUM pline = 1 + prefix_fuzz;
    register LINENUM iline;
    register LINENUM pat_lines = pch_ptrn_lines () - suffix_fuzz;
    size_t size;
    register char const *p;

    for (iline=base+offset+prefix_fuzz; pline <= pat_lines; pline++,iline++) {
        p = ifetch (iline, offset >= 0, &size);
        if (canonicalize) {
            if (!similar(p, size,
                         pfetch(pline),
                         pch_line_len(pline) ))
                return FALSE;
        }
        else if (size != pch_line_len (pline)
                 || memcmp (p, pfetch (pline), size) != 0)
            return FALSE;
    }
    return TRUE;
}

/* Do two lines match with canonicalized white space? */

static bool
similar (a, alen, b, blen)
     register char const *a;
     register size_t alen;
     register char const *b;
     register size_t blen;
{
  /* Ignore presence or absence of trailing newlines.  */
  alen  -=  alen && a[alen - 1] == '\n';
  blen  -=  blen && b[blen - 1] == '\n';

  for (;;)
    {
      if (!blen || (*b == ' ' || *b == '\t'))
        {
          while (blen && (*b == ' ' || *b == '\t'))
            b++, blen--;
          if (alen)
            {
              if (!(*a == ' ' || *a == '\t'))
                return FALSE;
              do a++, alen--;
              while (alen && (*a == ' ' || *a == '\t'));
            }
          if (!alen || !blen)
            return alen == blen;
        }
      else if (!alen || *a++ != *b++)
        return FALSE;
      else
        alen--, blen--;
    }
}

/* Make a temporary file.  */

#if HAVE_MKTEMP
char *mktemp PARAMS ((char *));
#endif

#ifndef TMPDIR
#define TMPDIR "/tmp"
#endif

static char const *
make_temp (letter)
     int letter;
{
  char *r;
#if HAVE_MKTEMP
  char const *tmpdir = getenv ("TMPDIR");       /* Unix tradition */
  if (!tmpdir) tmpdir = getenv ("TMP");         /* DOS tradition */
  if (!tmpdir) tmpdir = getenv ("TEMP");        /* another DOS tradition */
  if (!tmpdir) tmpdir = TMPDIR;
  r = xmalloc (strlen (tmpdir) + 10);
  sprintf (r, "%s/p%cXXXXXX", tmpdir, letter);
  mktemp (r);
  if (!*r)
    pfatal ("mktemp");
#else
  r = xmalloc (L_tmpnam);
  if (! (tmpnam (r) == r && *r))
    pfatal ("tmpnam");
#endif
  return r;
}

/* Fatal exit with cleanup. */

void
fatal_exit (sig)
     int sig;
{
  cleanup ();

  if (sig)
    exit_with_signal (sig);

  exit (2);
}

static void
cleanup ()
{
  unlink (TMPINNAME);
  unlink (TMPOUTNAME);
  unlink (TMPPATNAME);
  unlink (TMPREJNAME);
}