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/* reading patches */

/* $Id: pch.c,v 1.26 1997/07/21 17:59:46 eggert Exp $ */

/*
Copyright 1986, 1987, 1988 Larry Wall
Copyright 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 extern
#include <common.h>
#include <backupfile.h>
#include <inp.h>
#include <util.h>
#undef XTERN
#define XTERN
#include <pch.h>

#define INITHUNKMAX 125                 /* initial dynamic allocation size */

/* Patch (diff listing) abstract type. */

static FILE *pfp;                       /* patch file pointer */
static int p_says_nonexistent[2];       /* [0] for old file, [1] for new;
                value is 0 for nonempty, 1 for empty, 2 for nonexistent */
static int p_rfc934_nesting;            /* RFC 934 nesting level */
static time_t p_timestamp[2];           /* timestamps in patch headers */
static off_t p_filesize;                /* size of the patch file */
static LINENUM p_first;                 /* 1st line number */
static LINENUM p_newfirst;              /* 1st line number of replacement */
static LINENUM p_ptrn_lines;            /* # lines in pattern */
static LINENUM p_repl_lines;            /* # lines in replacement text */
static LINENUM p_end = -1;              /* last line in hunk */
static LINENUM p_max;                   /* max allowed value of p_end */
static LINENUM p_prefix_context;        /* # of prefix context lines */
static LINENUM p_suffix_context;        /* # of suffix context lines */
static LINENUM p_input_line;            /* current line # from patch file */
static char **p_line;                   /* the text of the hunk */
static size_t *p_len;                   /* line length including \n if any */
static char *p_Char;                    /* +, -, and ! */
static LINENUM hunkmax = INITHUNKMAX;   /* size of above arrays */
static int p_indent;                    /* indent to patch */
static file_offset p_base;              /* where to intuit this time */
static LINENUM p_bline;                 /* line # of p_base */
static file_offset p_start;             /* where intuit found a patch */
static LINENUM p_sline;                 /* and the line number for it */
static LINENUM p_hunk_beg;              /* line number of current hunk */
static LINENUM p_efake = -1;            /* end of faked up lines--don't free */
static LINENUM p_bfake = -1;            /* beg of faked up lines */

enum nametype { OLD, NEW, INDEX, NONE };

static enum diff intuit_diff_type PARAMS ((void));
static enum nametype best_name PARAMS ((char * const *, int const *));
static int prefix_components PARAMS ((char *, int));
static size_t pget_line PARAMS ((int, int));
static size_t get_line PARAMS ((void));
static bool incomplete_line PARAMS ((void));
static bool grow_hunkmax PARAMS ((void));
static void malformed PARAMS ((void)) __attribute__ ((noreturn));
static void next_intuit_at PARAMS ((file_offset, LINENUM));
static void skip_to PARAMS ((file_offset, LINENUM));

/* Prepare to look for the next patch in the patch file. */

void
re_patch()
{
    p_first = 0;
    p_newfirst = 0;
    p_ptrn_lines = 0;
    p_repl_lines = 0;
    p_end = -1;
    p_max = 0;
    p_indent = 0;
}

/* Open the patch file at the beginning of time. */

void
open_patch_file(filename)
     char const *filename;
{
    file_offset file_pos = 0;
    struct stat st;
    if (!filename || !*filename || strEQ (filename, "-"))
      {
        file_offset stdin_pos;
#if HAVE_SETMODE
        if (binary_transput)
          {
            if (isatty (STDIN_FILENO))
              fatal ("cannot read binary data from tty on this platform");
            setmode (STDIN_FILENO, O_BINARY);
          }
#endif
        if (fstat (STDIN_FILENO, &st) != 0)
          pfatal ("fstat");
        if (S_ISREG (st.st_mode) && (stdin_pos = file_tell (stdin)) != -1)
          {
            pfp = stdin;
            file_pos = stdin_pos;
          }
        else
          {
            size_t charsread;
            pfp = fopen (TMPPATNAME, "w+b");
            if (!pfp)
              pfatal ("can't create `%s'", TMPPATNAME);
            for (st.st_size = 0;
                 (charsread = fread (buf, 1, bufsize, stdin)) != 0;
                 st.st_size += charsread)
              if (fwrite (buf, 1, charsread, pfp) != charsread)
                write_fatal ();
            if (ferror (stdin) || fclose (stdin) != 0)
              read_fatal ();
            if (fflush (pfp) != 0
                || file_seek (pfp, (file_offset) 0, SEEK_SET) != 0)
              write_fatal ();
          }
      }
    else
      {
        pfp = fopen (filename, binary_transput ? "rb" : "r");
        if (!pfp)
          pfatal ("can't open patch file `%s'", filename);
        if (fstat (fileno (pfp), &st) != 0)
          pfatal ("fstat");
      }
    p_filesize = st.st_size;
    if (p_filesize != (file_offset) p_filesize)
      fatal ("patch file is too long");
    next_intuit_at (file_pos, (LINENUM) 1);
    set_hunkmax();
}

/* Make sure our dynamically realloced tables are malloced to begin with. */

void
set_hunkmax()
{
    if (!p_line)
        p_line = (char **) malloc (hunkmax * sizeof *p_line);
    if (!p_len)
        p_len = (size_t *) malloc (hunkmax * sizeof *p_len);
    if (!p_Char)
        p_Char = malloc (hunkmax * sizeof *p_Char);
}

/* Enlarge the arrays containing the current hunk of patch. */

static bool
grow_hunkmax()
{
    hunkmax *= 2;
    assert (p_line && p_len && p_Char);
    if ((p_line = (char **) realloc (p_line, hunkmax * sizeof (*p_line)))
        && (p_len = (size_t *) realloc (p_len, hunkmax * sizeof (*p_len)))
        && (p_Char = realloc (p_Char, hunkmax * sizeof (*p_Char))))
      return TRUE;
    if (!using_plan_a)
      memory_fatal ();
    /* Don't free previous values of p_line etc.,
       since some broken implementations free them for us.
       Whatever is null will be allocated again from within plan_a (),
       of all places.  */
    return FALSE;
}

/* True if the remainder of the patch file contains a diff of some sort. */

bool
there_is_another_patch()
{
    if (p_base != 0 && p_base >= p_filesize) {
        if (verbosity == VERBOSE)
            say ("done\n");
        return FALSE;
    }
    if (verbosity == VERBOSE)
        say ("Hmm...");
    diff_type = intuit_diff_type();
    if (diff_type == NO_DIFF) {
        if (verbosity == VERBOSE)
          say (p_base
               ? "  Ignoring the trailing garbage.\ndone\n"
               : "  I can't seem to find a patch in there anywhere.\n");
        if (! p_base && p_filesize)
          fatal ("Only garbage was found in the patch input.");
        return FALSE;
    }
    if (skip_rest_of_patch)
      {
        Fseek (pfp, p_start, SEEK_SET);
        p_input_line = p_sline - 1;
        return TRUE;
      }
    if (verbosity == VERBOSE)
        say ("  %sooks like %s to me...\n",
            (p_base == 0 ? "L" : "The next patch l"),
            diff_type == UNI_DIFF ? "a unified diff" :
            diff_type == CONTEXT_DIFF ? "a context diff" :
            diff_type == NEW_CONTEXT_DIFF ? "a new-style context diff" :
            diff_type == NORMAL_DIFF ? "a normal diff" :
            "an ed script" );

    if (verbosity != SILENT)
      {
        if (p_indent)
          say ("(Patch is indented %d space%s.)\n", p_indent, p_indent==1?"":"s");
        if (! inname)
          {
            say ("can't find file to patch at input line %ld\n",
                 p_sline);
            say (strippath == INT_MAX
                 ? "Perhaps you should have used the -p or --strip option?\n"
                 : "Perhaps you used the wrong -p or --strip option?\n");
          }
      }

    skip_to(p_start,p_sline);
    while (!inname) {
        if (force || batch) {
            say ("No file to patch.  Skipping patch.\n");
            skip_rest_of_patch = TRUE;
            return TRUE;
        }
        ask ("File to patch: ");
        inname = fetchname (buf, 0, (time_t *) 0);
        if (inname)
          {
            if (stat (inname, &instat) == 0)
              {
                inerrno = 0;
                invc = -1;
              }
            else
              {
                perror (inname);
                free (inname);
                inname = 0;
              }
          }
        if (!inname) {
            ask ("Skip this patch? [y] ");
            if (*buf != 'n') {
                if (verbosity != SILENT)
                    say ("Skipping patch.\n");
                skip_rest_of_patch = TRUE;
                return TRUE;
            }
        }
    }
    return TRUE;
}

/* Determine what kind of diff is in the remaining part of the patch file. */

static enum diff
intuit_diff_type()
{
    register char *s;
    register char *t;
    register int indent;
    register file_offset this_line = 0;
    register file_offset previous_line;
    register file_offset first_command_line = -1;
    LINENUM fcl_line = 0; /* Pacify `gcc -W'.  */
    register bool last_line_was_command = FALSE;
    register bool this_is_a_command = FALSE;
    register bool stars_last_line = FALSE;
    register bool stars_this_line = FALSE;
    enum nametype i;
    char *name[3];
    struct stat st[3];
    int stat_errno[3];
    int version_controlled[3];
    register enum diff retval;

    name[OLD] = name[NEW] = name[INDEX] = 0;
    version_controlled[OLD] = -1;
    version_controlled[NEW] = -1;
    version_controlled[INDEX] = -1;
    p_rfc934_nesting = 0;
    p_timestamp[OLD] = p_timestamp[NEW] = (time_t) -1;
    p_says_nonexistent[OLD] = p_says_nonexistent[NEW] = 0;
    Fseek (pfp, p_base, SEEK_SET);
    p_input_line = p_bline - 1;
    for (;;) {
        previous_line = this_line;
        last_line_was_command = this_is_a_command;
        stars_last_line = stars_this_line;
        this_line = file_tell (pfp);
        indent = 0;
        if (! pget_line (0, 0)) {
            if (first_command_line >= 0) {
                                        /* nothing but deletes!? */
                p_start = first_command_line;
                p_sline = fcl_line;
                retval = ED_DIFF;
                goto scan_exit;
            }
            else {
                p_start = this_line;
                p_sline = p_input_line;
                return NO_DIFF;
            }
        }
        for (s = buf; *s == ' ' || *s == '\t' || *s == 'X'; s++) {
            if (*s == '\t')
                indent = (indent + 8) & ~7;
            else
                indent++;
        }
        for (t = s;  ISDIGIT (*t) || *t == ',';  t++)
          continue;
        this_is_a_command = (ISDIGIT (*s) &&
          (*t == 'd' || *t == 'c' || *t == 'a') );
        if (first_command_line < 0 && this_is_a_command) {
            first_command_line = this_line;
            fcl_line = p_input_line;
            p_indent = indent;          /* assume this for now */
        }
        if (!stars_last_line && strnEQ(s, "*** ", 4))
            name[OLD] = fetchname (s+4, strippath, &p_timestamp[OLD]);
        else if (strnEQ(s, "+++ ", 4))
            /* Swap with NEW below.  */
            name[OLD] = fetchname (s+4, strippath, &p_timestamp[OLD]);
        else if (strnEQ(s, "Index:", 6))
            name[INDEX] = fetchname (s+6, strippath, (time_t *) 0);
        else if (strnEQ(s, "Prereq:", 7)) {
            for (t = s + 7;  ISSPACE ((unsigned char) *t);  t++)
              continue;
            revision = t;
            for (t = revision;  *t && !ISSPACE ((unsigned char) *t);  t++)
              continue;
            if (t == revision)
                revision = 0;
            else {
                char oldc = *t;
                *t = '\0';
                revision = savestr (revision);
                *t = oldc;
            }
        } else
          {
            for (t = s;  t[0] == '-' && t[1] == ' ';  t += 2)
              continue;
            if (strnEQ(t, "--- ", 4))
              {
                time_t timestamp = (time_t) -1;
                name[NEW] = fetchname (t+4, strippath, &timestamp);
                if (timestamp != (time_t) -1)
                  {
                    p_timestamp[NEW] = timestamp;
                    p_rfc934_nesting = (t - s) >> 1;
                  }
              }
          }
        if ((diff_type == NO_DIFF || diff_type == ED_DIFF) &&
          first_command_line >= 0 &&
          strEQ(s, ".\n") ) {
            p_indent = indent;
            p_start = first_command_line;
            p_sline = fcl_line;
            retval = ED_DIFF;
            goto scan_exit;
        }
        if ((diff_type == NO_DIFF || diff_type == UNI_DIFF)
            && strnEQ(s, "@@ -", 4)) {

            /* `name' and `p_timestamp' are backwards; swap them.  */
            time_t ti = p_timestamp[OLD];
            p_timestamp[OLD] = p_timestamp[NEW];
            p_timestamp[NEW] = ti;
            t = name[OLD];
            name[OLD] = name[NEW];
            name[NEW] = t;

            s += 4;
            if (! atol (s))
              p_says_nonexistent[OLD] = 1 + ! p_timestamp[OLD];
            while (*s != ' ' && *s != '\n')
              s++;
            while (*s == ' ')
              s++;
            if (! atol (s))
              p_says_nonexistent[NEW] = 1 + ! p_timestamp[NEW];
            p_indent = indent;
            p_start = this_line;
            p_sline = p_input_line;
            retval = UNI_DIFF;
            if (! ((name[OLD] || ! p_timestamp[OLD])
                   && (name[NEW] || ! p_timestamp[NEW])))
              say ("missing header for unified diff at line %ld of patch\n",
                   p_sline);
            goto scan_exit;
        }
        stars_this_line = strnEQ(s, "********", 8);
        if ((diff_type == NO_DIFF
             || diff_type == CONTEXT_DIFF
             || diff_type == NEW_CONTEXT_DIFF)
            && stars_last_line && strnEQ (s, "*** ", 4)) {
            s += 4;
            if (! atol (s))
              p_says_nonexistent[OLD] = 1 + ! p_timestamp[OLD];
            /* if this is a new context diff the character just before */
            /* the newline is a '*'. */
            while (*s != '\n')
                s++;
            p_indent = indent;
            p_start = previous_line;
            p_sline = p_input_line - 1;
            retval = (*(s-1) == '*' ? NEW_CONTEXT_DIFF : CONTEXT_DIFF);

            {
              /* Scan the first hunk to see whether the file contents
                 appear to have been deleted.  */
              file_offset saved_p_base = p_base;
              LINENUM saved_p_bline = p_bline;
              Fseek (pfp, previous_line, SEEK_SET);
              p_input_line -= 2;
              if (another_hunk (retval, 0)
                  && ! p_repl_lines && p_newfirst == 1)
                p_says_nonexistent[NEW] = 1 + ! p_timestamp[NEW];
              next_intuit_at (saved_p_base, saved_p_bline);
            }

            if (! ((name[OLD] || ! p_timestamp[OLD])
                   && (name[NEW] || ! p_timestamp[NEW])))
              say ("missing header for context diff at line %ld of patch\n",
                   p_sline);
            goto scan_exit;
        }
        if ((diff_type == NO_DIFF || diff_type == NORMAL_DIFF) &&
          last_line_was_command &&
          (strnEQ(s, "< ", 2) || strnEQ(s, "> ", 2)) ) {
            p_start = previous_line;
            p_sline = p_input_line - 1;
            p_indent = indent;
            retval = NORMAL_DIFF;
            goto scan_exit;
        }
    }

  scan_exit:

    /* To intuit `inname', the name of the file to patch,
       use the algorithm specified by POSIX 1003.2b/D11 section 5.22.7.2
       (with some modifications if posixly_correct is zero):

       - Take the old and new names from the context header if present,
         and take the index name from the `Index:' line if present and
         if either the old and new names are both absent
         or posixly_correct is nonzero.
         Consider the file names to be in the order (old, new, index).
       - If some named files exist, use the first one if posixly_correct
         is nonzero, the best one otherwise.
       - If patch_get is nonzero, and no named files exist,
         but an RCS or SCCS master file exists,
         use the first named file with an RCS or SCCS master.
       - If no named files exist, no RCS or SCCS master was found,
         some names are given, posixly_correct is zero,
         and the patch appears to create a file, then use the best name
         requiring the creation of the fewest directories.
       - Otherwise, report failure by setting `inname' to 0;
         this causes our invoker to ask the user for a file name.  */

    i = NONE;

    if (!inname)
      {
        enum nametype i0 = NONE;

        if (! posixly_correct && (name[OLD] || name[NEW]) && name[INDEX])
          {
            free (name[INDEX]);
            name[INDEX] = 0;
          }

        for (i = OLD;  i <= INDEX;  i++)
          if (name[i])
            {
              if (i0 != NONE && strcmp (name[i0], name[i]) == 0)
                {
                  /* It's the same name as before; reuse stat results.  */
                  stat_errno[i] = stat_errno[i0];
                  if (! stat_errno[i])
                    st[i] = st[i0];
                }
              else if (stat (name[i], &st[i]) != 0)
                stat_errno[i] = errno;
              else
                {
                  stat_errno[i] = 0;
                  if (posixly_correct)
                    break;
                }
              i0 = i;
            }

        if (! posixly_correct)
          {
            i = best_name (name, stat_errno);

            if (i == NONE && patch_get)
              {
                enum nametype nope = NONE;

                for (i = OLD;  i <= INDEX;  i++)
                  if (name[i])
                    {
                      char const *cs;
                      char *getbuf;
                      char *diffbuf;
                      int readonly = outfile && strcmp (outfile, name[i]) != 0;

                      if (nope == NONE || strcmp (name[nope], name[i]) != 0)
                        {
                          cs = (version_controller
                                (name[i], readonly, (struct stat *) 0,
                                 &getbuf, &diffbuf));
                          version_controlled[i] = !! cs;
                          if (cs)
                            {
                              if (version_get (name[i], cs, 0, readonly,
                                               getbuf, &st[i]))
                                stat_errno[i] = 0;
                              else
                                version_controlled[i] = 0;

                              free (getbuf);
                              free (diffbuf);

                              if (! stat_errno[i])
                                break;
                            }
                        }

                      nope = i;
                    }
              }

            if (p_says_nonexistent[reverse ^ (i == NONE || st[i].st_size == 0)])
              {
                assert (i0 != NONE);
                if (ok_to_reverse
                    ("The next patch%s would %s the file `%s',\nwhich %s!",
                     reverse ? ", when reversed," : "",
                     (i == NONE ? "delete"
                      : st[i].st_size == 0 ? "empty out"
                      : "create"),
                     name[i == NONE || st[i].st_size == 0 ? i0 : i],
                     (i == NONE ? "does not exist"
                      : st[i].st_size == 0 ? "is already empty"
                      : "already exists")))
                  reverse ^= 1;
              }

            if (i == NONE && p_says_nonexistent[reverse])
              {
                int newdirs[3];
                int newdirs_min = INT_MAX;
                int distance_from_minimum[3];

                for (i = OLD;  i <= INDEX;  i++)
                  if (name[i])
                    {
                      newdirs[i] = (prefix_components (name[i], 0)
                                    - prefix_components (name[i], 1));
                      if (newdirs[i] < newdirs_min)
                        newdirs_min = newdirs[i];
                    }

                for (i = OLD;  i <= INDEX;  i++)
                  if (name[i])
                    distance_from_minimum[i] = newdirs[i] - newdirs_min;

                i = best_name (name, distance_from_minimum);
              }
          }
      }

    if (i == NONE)
      inerrno = -1;
    else
      {
        inname = name[i];
        name[i] = 0;
        inerrno = stat_errno[i];
        invc = version_controlled[i];
        instat = st[i];
      }

    for (i = OLD;  i <= INDEX;  i++)
      if (name[i])
        free (name[i]);

    return retval;
}

/* Count the path name components in FILENAME's prefix.
   If CHECKDIRS is nonzero, count only existing directories.  */
static int
prefix_components (filename, checkdirs)
     char *filename;
     int checkdirs;
{
  int count = 0;
  struct stat stat_buf;
  int stat_result;
  char *f = filename + FILESYSTEM_PREFIX_LEN (filename);

  if (*f)
    while (*++f)
      if (ISSLASH (f[0]) && ! ISSLASH (f[-1]))
        {
          if (checkdirs)
            {
              *f = '\0';
              stat_result = stat (filename, &stat_buf);
              *f = '/';
              if (! (stat_result == 0 && S_ISDIR (stat_buf.st_mode)))
                break;
            }

          count++;
        }

  return count;
}

/* Return the index of the best of NAME[OLD], NAME[NEW], and NAME[INDEX].
   Ignore null names, and ignore NAME[i] if IGNORE[i] is nonzero.
   Return NONE if all names are ignored.  */
static enum nametype
best_name (name, ignore)
     char *const *name;
     int const *ignore;
{
  enum nametype i;
  int components[3];
  int components_min = INT_MAX;
  size_t basename_len[3];
  size_t basename_len_min = (size_t) -1;
  size_t len[3];
  size_t len_min = (size_t) -1;

  for (i = OLD;  i <= INDEX;  i++)
    if (name[i] && !ignore[i])
      {
        /* Take the names with the fewest prefix components.  */
        components[i] = prefix_components (name[i], 0);
        if (components_min < components[i])
          continue;
        components_min = components[i];

        /* Of those, take the names with the shortest basename.  */
        basename_len[i] = strlen (base_name (name[i]));
        if (basename_len_min < basename_len[i])
          continue;
        basename_len_min = basename_len[i];

        /* Of those, take the shortest names.  */
        len[i] = strlen (name[i]);
        if (len_min < len[i])
          continue;
        len_min = len[i];
      }

  /* Of those, take the first name.  */
  for (i = OLD;  i <= INDEX;  i++)
    if (name[i] && !ignore[i]
        && components[i] == components_min
        && basename_len[i] == basename_len_min
        && len[i] == len_min)
      break;

  return i;
}

/* Remember where this patch ends so we know where to start up again. */

static void
next_intuit_at(file_pos,file_line)
file_offset file_pos;
LINENUM file_line;
{
    p_base = file_pos;
    p_bline = file_line;
}

/* Basically a verbose fseek() to the actual diff listing. */

static void
skip_to(file_pos,file_line)
file_offset file_pos;
LINENUM file_line;
{
    register FILE *i = pfp;
    register FILE *o = stdout;
    register int c;

    assert(p_base <= file_pos);
    if ((verbosity == VERBOSE || !inname) && p_base < file_pos) {
        Fseek (i, p_base, SEEK_SET);
        say ("The text leading up to this was:\n--------------------------\n");

        while (file_tell (i) < file_pos)
          {
            putc ('|', o);
            do
              {
                if ((c = getc (i)) == EOF)
                  read_fatal ();
                putc (c, o);
              }
            while (c != '\n');
          }

        say ("--------------------------\n");
    }
    else
        Fseek (i, file_pos, SEEK_SET);
    p_input_line = file_line - 1;
}

/* Make this a function for better debugging.  */
static void
malformed ()
{
    fatal ("malformed patch at line %ld: %s", p_input_line, buf);
                /* about as informative as "Syntax error" in C */
}

/* 1 if there is more of the current diff listing to process;
   0 if not; -1 if ran out of memory. */

int
another_hunk (difftype, rev)
     enum diff difftype;
     int rev;
{
    register char *s;
    register LINENUM context = 0;
    register size_t chars_read;

    while (p_end >= 0) {
        if (p_end == p_efake)
            p_end = p_bfake;            /* don't free twice */
        else
            free(p_line[p_end]);
        p_end--;
    }
    assert(p_end == -1);
    p_efake = -1;

    p_max = hunkmax;                    /* gets reduced when --- found */
    if (difftype == CONTEXT_DIFF || difftype == NEW_CONTEXT_DIFF) {
        file_offset line_beginning = file_tell (pfp);
                                        /* file pos of the current line */
        LINENUM repl_beginning = 0;     /* index of --- line */
        register LINENUM fillcnt = 0;   /* #lines of missing ptrn or repl */
        register LINENUM fillsrc;       /* index of first line to copy */
        register LINENUM filldst;       /* index of first missing line */
        bool ptrn_spaces_eaten = FALSE; /* ptrn was slightly misformed */
        bool some_context = FALSE;      /* (perhaps internal) context seen */
        register bool repl_could_be_missing = TRUE;
        bool repl_missing = FALSE;      /* we are now backtracking */
        file_offset repl_backtrack_position = 0;
                                        /* file pos of first repl line */
        LINENUM repl_patch_line;        /* input line number for same */
        LINENUM repl_context;           /* context for same */
        LINENUM ptrn_prefix_context = -1; /* lines in pattern prefix context */
        LINENUM ptrn_suffix_context = -1; /* lines in pattern suffix context */
        LINENUM repl_prefix_context = -1; /* lines in replac. prefix context */
        register LINENUM ptrn_copiable = 0;
                                        /* # of copiable lines in ptrn */

        /* Pacify `gcc -Wall'.  */
        fillsrc = filldst = repl_patch_line = repl_context = 0;

        chars_read = get_line ();
        if (chars_read == (size_t) -1
            || chars_read <= 8
            || strncmp (buf, "********", 8) != 0) {
            next_intuit_at(line_beginning,p_input_line);
            return chars_read == (size_t) -1 ? -1 : 0;
        }
        p_hunk_beg = p_input_line + 1;
        while (p_end < p_max) {
            chars_read = get_line ();
            if (chars_read == (size_t) -1)
              return -1;
            if (!chars_read) {
                if (repl_beginning && repl_could_be_missing) {
                    repl_missing = TRUE;
                    goto hunk_done;
                }
                if (p_max - p_end < 4) {
                    strcpy (buf, "  \n");  /* assume blank lines got chopped */
                    chars_read = 3;
                } else {
                    fatal ("unexpected end of file in patch");
                }
            }
            p_end++;
            if (p_end == hunkmax)
                fatal ("unterminated hunk starting at line %ld; giving up at line %ld: %s",
                       pch_hunk_beg (), p_input_line, buf);
            assert(p_end < hunkmax);
            p_Char[p_end] = *buf;
            p_len[p_end] = 0;
            p_line[p_end] = 0;
            switch (*buf) {
            case '*':
                if (strnEQ(buf, "********", 8)) {
                    if (repl_beginning && repl_could_be_missing) {
                        repl_missing = TRUE;
                        goto hunk_done;
                    }
                    else
                        fatal ("unexpected end of hunk at line %ld",
                            p_input_line);
                }
                if (p_end != 0) {
                    if (repl_beginning && repl_could_be_missing) {
                        repl_missing = TRUE;
                        goto hunk_done;
                    }
                    fatal ("unexpected `***' at line %ld: %s",
                           p_input_line, buf);
                }
                context = 0;
                p_len[p_end] = strlen (buf);
                if (! (p_line[p_end] = savestr (buf))) {
                    p_end--;
                    return -1;
                }
                for (s = buf;  *s && !ISDIGIT (*s);  s++)
                  continue;
                if (!*s)
                    malformed ();
                if (strnEQ(s,"0,0",3))
                    remove_prefix (s, 2);
                p_first = (LINENUM) atol(s);
                while (ISDIGIT (*s))
                  s++;
                if (*s == ',') {
                    while (*s && !ISDIGIT (*s))
                      s++;
                    if (!*s)
                        malformed ();
                    p_ptrn_lines = ((LINENUM)atol(s)) - p_first + 1;
                }
                else if (p_first)
                    p_ptrn_lines = 1;
                else {
                    p_ptrn_lines = 0;
                    p_first = 1;
                }
                p_max = p_ptrn_lines + 6;       /* we need this much at least */
                while (p_max >= hunkmax)
                    if (! grow_hunkmax ())
                        return -1;
                p_max = hunkmax;
                break;
            case '-':
                if (buf[1] != '-')
                  goto change_line;
                if (ptrn_prefix_context == -1)
                  ptrn_prefix_context = context;
                ptrn_suffix_context = context;
                if (repl_beginning
                    || (p_end
                        != p_ptrn_lines + 1 + (p_Char[p_end - 1] == '\n')))
                  {
                    if (p_end == 1)
                      {
                        /* `Old' lines were omitted.  Set up to fill
                           them in from `new' context lines.  */
                        p_end = p_ptrn_lines + 1;
                        ptrn_prefix_context = ptrn_suffix_context = -1;
                        fillsrc = p_end + 1;
                        filldst = 1;
                        fillcnt = p_ptrn_lines;
                      }
                    else if (! repl_beginning)
                      fatal ("%s `---' at line %ld; check line numbers at line %ld",
                             (p_end <= p_ptrn_lines
                              ? "Premature"
                              : "Overdue"),
                             p_input_line, p_hunk_beg);
                    else if (! repl_could_be_missing)
                      fatal ("duplicate `---' at line %ld; check line numbers at line %ld",
                             p_input_line, p_hunk_beg + repl_beginning);
                    else
                      {
                        repl_missing = TRUE;
                        goto hunk_done;
                      }
                  }
                repl_beginning = p_end;
                repl_backtrack_position = file_tell (pfp);
                repl_patch_line = p_input_line;
                repl_context = context;
                p_len[p_end] = strlen (buf);
                if (! (p_line[p_end] = savestr (buf)))
                  {
                    p_end--;
                    return -1;
                  }
                p_Char[p_end] = '=';
                for (s = buf;  *s && ! ISDIGIT (*s);  s++)
                  continue;
                if (!*s)
                  malformed ();
                p_newfirst = (LINENUM) atol (s);
                while (ISDIGIT (*s))
                  s++;
                if (*s == ',')
                  {
                    do
                      {
                        if (!*++s)
                          malformed ();
                      }
                    while (! ISDIGIT (*s));
                    p_repl_lines = (LINENUM) atol (s) - p_newfirst + 1;
                  }
                else if (p_newfirst)
                  p_repl_lines = 1;
                else
                  {
                    p_repl_lines = 0;
                    p_newfirst = 1;
                  }
                p_max = p_repl_lines + p_end;
                while (p_max >= hunkmax)
                  if (! grow_hunkmax ())
                    return -1;
                if (p_repl_lines != ptrn_copiable
                    && (p_prefix_context != 0
                        || context != 0
                        || p_repl_lines != 1))
                  repl_could_be_missing = FALSE;
                context = 0;
                break;
            case '+':  case '!':
                repl_could_be_missing = FALSE;
              change_line:
                s = buf + 1;
                chars_read--;
                if (*s == '\n' && canonicalize) {
                    strcpy (s, " \n");
                    chars_read = 2;
                }
                if (*s == ' ' || *s == '\t') {
                    s++;
                    chars_read--;
                } else if (repl_beginning && repl_could_be_missing) {
                    repl_missing = TRUE;
                    goto hunk_done;
                }
                if (! repl_beginning)
                  {
                    if (ptrn_prefix_context == -1)
                      ptrn_prefix_context = context;
                  }
                else
                  {
                    if (repl_prefix_context == -1)
                      repl_prefix_context = context;
                  }
                chars_read -=
                  (1 < chars_read
                   && p_end == (repl_beginning ? p_max : p_ptrn_lines)
                   && incomplete_line ());
                p_len[p_end] = chars_read;
                if (! (p_line[p_end] = savebuf (s, chars_read))) {
                    p_end--;
                    return -1;
                }
                context = 0;
                break;
            case '\t': case '\n':       /* assume spaces got eaten */
                s = buf;
                if (*buf == '\t') {
                    s++;
                    chars_read--;
                }
                if (repl_beginning && repl_could_be_missing &&
                    (!ptrn_spaces_eaten || difftype == NEW_CONTEXT_DIFF) ) {
                    repl_missing = TRUE;
                    goto hunk_done;
                }
                chars_read -=
                  (1 < chars_read
                   && p_end == (repl_beginning ? p_max : p_ptrn_lines)
                   && incomplete_line ());
                p_len[p_end] = chars_read;
                if (! (p_line[p_end] = savebuf (buf, chars_read))) {
                    p_end--;
                    return -1;
                }
                if (p_end != p_ptrn_lines + 1) {
                    ptrn_spaces_eaten |= (repl_beginning != 0);
                    some_context = TRUE;
                    context++;
                    if (!repl_beginning)
                        ptrn_copiable++;
                    p_Char[p_end] = ' ';
                }
                break;
            case ' ':
                s = buf + 1;
                chars_read--;
                if (*s == '\n' && canonicalize) {
                    strcpy (s, "\n");
                    chars_read = 2;
                }
                if (*s == ' ' || *s == '\t') {
                    s++;
                    chars_read--;
                } else if (repl_beginning && repl_could_be_missing) {
                    repl_missing = TRUE;
                    goto hunk_done;
                }
                some_context = TRUE;
                context++;
                if (!repl_beginning)
                    ptrn_copiable++;
                chars_read -=
                  (1 < chars_read
                   && p_end == (repl_beginning ? p_max : p_ptrn_lines)
                   && incomplete_line ());
                p_len[p_end] = chars_read;
                if (! (p_line[p_end] = savebuf (buf + 2, chars_read))) {
                    p_end--;
                    return -1;
                }
                break;
            default:
                if (repl_beginning && repl_could_be_missing) {
                    repl_missing = TRUE;
                    goto hunk_done;
                }
                malformed ();
            }
        }

    hunk_done:
        if (p_end >=0 && !repl_beginning)
            fatal ("no `---' found in patch at line %ld", pch_hunk_beg ());

        if (repl_missing) {

            /* reset state back to just after --- */
            p_input_line = repl_patch_line;
            context = repl_context;
            for (p_end--; p_end > repl_beginning; p_end--)
                free(p_line[p_end]);
            Fseek (pfp, repl_backtrack_position, SEEK_SET);

            /* redundant 'new' context lines were omitted - set */
            /* up to fill them in from the old file context */
            fillsrc = 1;
            filldst = repl_beginning+1;
            fillcnt = p_repl_lines;
            p_end = p_max;
        }
        else if (!some_context && fillcnt == 1) {
            /* the first hunk was a null hunk with no context */
            /* and we were expecting one line -- fix it up. */
            while (filldst < p_end) {
                p_line[filldst] = p_line[filldst+1];
                p_Char[filldst] = p_Char[filldst+1];
                p_len[filldst] = p_len[filldst+1];
                filldst++;
            }
#if 0
            repl_beginning--;           /* this doesn't need to be fixed */
#endif
            p_end--;
            p_first++;                  /* do append rather than insert */
            fillcnt = 0;
            p_ptrn_lines = 0;
        }

        p_prefix_context = ((repl_prefix_context == -1
                             || (ptrn_prefix_context != -1
                                 && ptrn_prefix_context < repl_prefix_context))
                            ? ptrn_prefix_context : repl_prefix_context);
        p_suffix_context = ((ptrn_suffix_context != -1
                             && ptrn_suffix_context < context)
                            ? ptrn_suffix_context : context);
        assert (p_prefix_context != -1 && p_suffix_context != -1);

        if (difftype == CONTEXT_DIFF
            && (fillcnt
                || (p_first > 1
                    && p_prefix_context + p_suffix_context < ptrn_copiable))) {
            if (verbosity == VERBOSE)
                say ("%s\n%s\n%s\n",
"(Fascinating -- this is really a new-style context diff but without",
"the telltale extra asterisks on the *** line that usually indicate",
"the new style...)");
            diff_type = difftype = NEW_CONTEXT_DIFF;
        }

        /* if there were omitted context lines, fill them in now */
        if (fillcnt) {
            p_bfake = filldst;          /* remember where not to free() */
            p_efake = filldst + fillcnt - 1;
            while (fillcnt-- > 0) {
                while (fillsrc <= p_end && fillsrc != repl_beginning
                       && p_Char[fillsrc] != ' ')
                    fillsrc++;
                if (p_end < fillsrc || fillsrc == repl_beginning)
                    fatal ("replacement text or line numbers mangled in hunk at line %ld",
                        p_hunk_beg);
                p_line[filldst] = p_line[fillsrc];
                p_Char[filldst] = p_Char[fillsrc];
                p_len[filldst] = p_len[fillsrc];
                fillsrc++; filldst++;
            }
            while (fillsrc <= p_end && fillsrc != repl_beginning)
              {
                if (p_Char[fillsrc] == ' ')
                  fatal ("replacement text or line numbers mangled in hunk at line %ld",
                         p_hunk_beg);
                fillsrc++;
              }
            if (debug & 64)
                printf("fillsrc %ld, filldst %ld, rb %ld, e+1 %ld\n",
                    fillsrc,filldst,repl_beginning,p_end+1);
            assert(fillsrc==p_end+1 || fillsrc==repl_beginning);
            assert(filldst==p_end+1 || filldst==repl_beginning);
        }
    }
    else if (difftype == UNI_DIFF) {
        file_offset line_beginning = file_tell (pfp);
                                        /* file pos of the current line */
        register LINENUM fillsrc;       /* index of old lines */
        register LINENUM filldst;       /* index of new lines */
        char ch = '\0';

        chars_read = get_line ();
        if (chars_read == (size_t) -1
            || chars_read <= 4
            || strncmp (buf, "@@ -", 4) != 0) {
            next_intuit_at(line_beginning,p_input_line);
            return chars_read == (size_t) -1 ? -1 : 0;
        }
        s = buf+4;
        if (!*s)
            malformed ();
        p_first = (LINENUM) atol(s);
        while (ISDIGIT (*s))
          s++;
        if (*s == ',') {
            p_ptrn_lines = (LINENUM) atol(++s);
            while (ISDIGIT (*s))
              s++;
        } else
            p_ptrn_lines = 1;
        if (*s == ' ') s++;
        if (*s != '+' || !*++s)
            malformed ();
        p_newfirst = (LINENUM) atol(s);
        while (ISDIGIT (*s))
          s++;
        if (*s == ',') {
            p_repl_lines = (LINENUM) atol(++s);
            while (ISDIGIT (*s))
              s++;
        } else
            p_repl_lines = 1;
        if (*s == ' ') s++;
        if (*s != '@')
            malformed ();
        if (!p_ptrn_lines)
            p_first++;                  /* do append rather than insert */
        if (!p_repl_lines)
            p_newfirst++;
        p_max = p_ptrn_lines + p_repl_lines + 1;
        while (p_max >= hunkmax)
            if (! grow_hunkmax ())
                return -1;
        fillsrc = 1;
        filldst = fillsrc + p_ptrn_lines;
        p_end = filldst + p_repl_lines;
        sprintf (buf,"*** %ld,%ld ****\n",p_first,p_first + p_ptrn_lines - 1);
        p_len[0] = strlen (buf);
        if (! (p_line[0] = savestr (buf))) {
            p_end = -1;
            return -1;
        }
        p_Char[0] = '*';
        sprintf (buf,"--- %ld,%ld ----\n",p_newfirst,p_newfirst+p_repl_lines-1);
        p_len[filldst] = strlen (buf);
        if (! (p_line[filldst] = savestr (buf))) {
            p_end = 0;
            return -1;
        }
        p_Char[filldst++] = '=';
        p_prefix_context = -1;
        p_hunk_beg = p_input_line + 1;
        while (fillsrc <= p_ptrn_lines || filldst <= p_end) {
            chars_read = get_line ();
            if (!chars_read) {
                if (p_max - filldst < 3) {
                    strcpy (buf, " \n");  /* assume blank lines got chopped */
                    chars_read = 2;
                } else {
                    fatal ("unexpected end of file in patch");
                }
            }
            if (chars_read == (size_t) -1)
                s = 0;
            else if (*buf == '\t' || *buf == '\n') {
                ch = ' ';               /* assume the space got eaten */
                s = savebuf (buf, chars_read);
            }
            else {
                ch = *buf;
                s = savebuf (buf+1, --chars_read);
            }
            if (!s) {
                while (--filldst > p_ptrn_lines)
                    free(p_line[filldst]);
                p_end = fillsrc-1;
                return -1;
            }
            switch (ch) {
            case '-':
                if (fillsrc > p_ptrn_lines) {
                    free(s);
                    p_end = filldst-1;
                    malformed ();
                }
                chars_read -= fillsrc == p_ptrn_lines && incomplete_line ();
                p_Char[fillsrc] = ch;
                p_line[fillsrc] = s;
                p_len[fillsrc++] = chars_read;
                break;
            case '=':
                ch = ' ';
                /* FALL THROUGH */
            case ' ':
                if (fillsrc > p_ptrn_lines) {
                    free(s);
                    while (--filldst > p_ptrn_lines)
                        free(p_line[filldst]);
                    p_end = fillsrc-1;
                    malformed ();
                }
                context++;
                chars_read -= fillsrc == p_ptrn_lines && incomplete_line ();
                p_Char[fillsrc] = ch;
                p_line[fillsrc] = s;
                p_len[fillsrc++] = chars_read;
                s = savebuf (s, chars_read);
                if (!s) {
                    while (--filldst > p_ptrn_lines)
                        free(p_line[filldst]);
                    p_end = fillsrc-1;
                    return -1;
                }
                /* FALL THROUGH */
            case '+':
                if (filldst > p_end) {
                    free(s);
                    while (--filldst > p_ptrn_lines)
                        free(p_line[filldst]);
                    p_end = fillsrc-1;
                    malformed ();
                }
                chars_read -= filldst == p_end && incomplete_line ();
                p_Char[filldst] = ch;
                p_line[filldst] = s;
                p_len[filldst++] = chars_read;
                break;
            default:
                p_end = filldst;
                malformed ();
            }
            if (ch != ' ') {
                if (p_prefix_context == -1)
                    p_prefix_context = context;
                context = 0;
            }
        }/* while */
        if (p_prefix_context == -1)
          malformed ();
        p_suffix_context = context;
    }
    else {                              /* normal diff--fake it up */
        char hunk_type;
        register int i;
        LINENUM min, max;
        file_offset line_beginning = file_tell (pfp);

        p_prefix_context = p_suffix_context = 0;
        chars_read = get_line ();
        if (chars_read == (size_t) -1 || !chars_read || !ISDIGIT (*buf)) {
            next_intuit_at(line_beginning,p_input_line);
            return chars_read == (size_t) -1 ? -1 : 0;
        }
        p_first = (LINENUM)atol(buf);
        for (s = buf;  ISDIGIT (*s);  s++)
          continue;
        if (*s == ',') {
            p_ptrn_lines = (LINENUM)atol(++s) - p_first + 1;
            while (ISDIGIT (*s))
              s++;
        }
        else
            p_ptrn_lines = (*s != 'a');
        hunk_type = *s;
        if (hunk_type == 'a')
            p_first++;                  /* do append rather than insert */
        min = (LINENUM)atol(++s);
        while (ISDIGIT (*s))
          s++;
        if (*s == ',')
            max = (LINENUM)atol(++s);
        else
            max = min;
        if (hunk_type == 'd')
            min++;
        p_end = p_ptrn_lines + 1 + max - min + 1;
        while (p_end >= hunkmax)
          if (! grow_hunkmax ())
            {
              p_end = -1;
              return -1;
            }
        p_newfirst = min;
        p_repl_lines = max - min + 1;
        sprintf (buf, "*** %ld,%ld\n", p_first, p_first + p_ptrn_lines - 1);
        p_len[0] = strlen (buf);
        if (! (p_line[0] = savestr (buf))) {
            p_end = -1;
            return -1;
        }
        p_Char[0] = '*';
        for (i=1; i<=p_ptrn_lines; i++) {
            chars_read = get_line ();
            if (chars_read == (size_t) -1)
              {
                p_end = i - 1;
                return -1;
              }
            if (!chars_read)
                fatal ("unexpected end of file in patch at line %ld",
                  p_input_line);
            if (buf[0] != '<' || (buf[1] != ' ' && buf[1] != '\t'))
                fatal ("`<' expected at line %ld of patch", p_input_line);
            chars_read -= 2 + (i == p_ptrn_lines && incomplete_line ());
            p_len[i] = chars_read;
            if (! (p_line[i] = savebuf (buf + 2, chars_read))) {
                p_end = i-1;
                return -1;
            }
            p_Char[i] = '-';
        }
        if (hunk_type == 'c') {
            chars_read = get_line ();
            if (chars_read == (size_t) -1)
              {
                p_end = i - 1;
                return -1;
              }
            if (! chars_read)
                fatal ("unexpected end of file in patch at line %ld",
                    p_input_line);
            if (*buf != '-')
                fatal ("`---' expected at line %ld of patch", p_input_line);
        }
        sprintf (buf, "--- %ld,%ld\n", min, max);
        p_len[i] = strlen (buf);
        if (! (p_line[i] = savestr (buf))) {
            p_end = i-1;
            return -1;
        }
        p_Char[i] = '=';
        for (i++; i<=p_end; i++) {
            chars_read = get_line ();
            if (chars_read == (size_t) -1)
              {
                p_end = i - 1;
                return -1;
              }
            if (!chars_read)
                fatal ("unexpected end of file in patch at line %ld",
                    p_input_line);
            if (buf[0] != '>' || (buf[1] != ' ' && buf[1] != '\t'))
                fatal ("`>' expected at line %ld of patch", p_input_line);
            chars_read -= 2 + (i == p_end && incomplete_line ());
            p_len[i] = chars_read;
            if (! (p_line[i] = savebuf (buf + 2, chars_read))) {
                p_end = i-1;
                return -1;
            }
            p_Char[i] = '+';
        }
    }
    if (rev)                            /* backwards patch? */
        if (!pch_swap())
            say ("Not enough memory to swap next hunk!\n");
    if (debug & 2) {
        LINENUM i;
        char special;

        for (i=0; i <= p_end; i++) {
            if (i == p_ptrn_lines)
                special = '^';
            else
                special = ' ';
            fprintf (stderr, "%3ld %c %c ", i, p_Char[i], special);
            pch_write_line (i, stderr);
            fflush (stderr);
        }
    }
    if (p_end+1 < hunkmax)      /* paranoia reigns supreme... */
        p_Char[p_end+1] = '^';  /* add a stopper for apply_hunk */
    return 1;
}

static size_t
get_line ()
{
   return pget_line (p_indent, p_rfc934_nesting);
}

/* Input a line from the patch file, worrying about indentation.
   Strip up to INDENT characters' worth of leading indentation.
   Then remove up to RFC934_NESTING instances of leading "- ".
   Ignore any partial lines at end of input, but warn about them.
   Succeed if a line was read; it is terminated by "\n\0" for convenience.
   Return the number of characters read, including '\n' but not '\0'.
   Return -1 if we ran out of memory.  */

static size_t
pget_line (indent, rfc934_nesting)
     int indent;
     int rfc934_nesting;
{
  register FILE *fp = pfp;
  register int c;
  register int i = 0;
  register char *b;
  register size_t s;

  for (;;)
    {
      c = getc (fp);
      if (c == EOF)
        {
          if (ferror (fp))
            read_fatal ();
          return 0;
        }
      if (indent <= i)
        break;
      if (c == ' ' || c == 'X')
        i++;
      else if (c == '\t')
        i = (i + 8) & ~7;
      else
        break;
    }

  i = 0;
  b = buf;

  while (c == '-' && 0 <= --rfc934_nesting)
    {
      c = getc (fp);
      if (c == EOF)
        goto patch_ends_in_middle_of_line;
      if (c != ' ')
        {
          i = 1;
          b[0] = '-';
          break;
        }
      c = getc (fp);
      if (c == EOF)
        goto patch_ends_in_middle_of_line;
    }

  s = bufsize;

  for (;;)
    {
      if (i == s - 1)
        {
          s *= 2;
          b = realloc (b, s);
          if (!b)
            {
              if (!using_plan_a)
                memory_fatal ();
              return (size_t) -1;
            }
          buf = b;
          bufsize = s;
        }
      b[i++] = c;
      if (c == '\n')
        break;
      c = getc (fp);
      if (c == EOF)
        goto patch_ends_in_middle_of_line;
    }

  b[i] = '\0';
  p_input_line++;
  return i;

 patch_ends_in_middle_of_line:
  if (ferror (fp))
    read_fatal ();
  say ("patch unexpectedly ends in middle of line\n");
  return 0;
}

static bool
incomplete_line ()
{
  register FILE *fp = pfp;
  register int c;
  register file_offset line_beginning = file_tell (fp);

  if (getc (fp) == '\\')
    {
      while ((c = getc (fp)) != '\n'  &&  c != EOF)
        continue;
      return TRUE;
    }
  else
    {
      /* We don't trust ungetc.  */
      Fseek (pfp, line_beginning, SEEK_SET);
      return FALSE;
    }
}

/* Reverse the old and new portions of the current hunk. */

bool
pch_swap()
{
    char **tp_line;             /* the text of the hunk */
    size_t *tp_len;             /* length of each line */
    char *tp_char;              /* +, -, and ! */
    register LINENUM i;
    register LINENUM n;
    bool blankline = FALSE;
    register char *s;

    i = p_first;
    p_first = p_newfirst;
    p_newfirst = i;

    /* make a scratch copy */

    tp_line = p_line;
    tp_len = p_len;
    tp_char = p_Char;
    p_line = 0; /* force set_hunkmax to allocate again */
    p_len = 0;
    p_Char = 0;
    set_hunkmax();
    if (!p_line || !p_len || !p_Char) {
        if (p_line)
          free (p_line);
        p_line = tp_line;
        if (p_len)
          free (p_len);
        p_len = tp_len;
        if (p_Char)
          free (p_Char);
        p_Char = tp_char;
        return FALSE;           /* not enough memory to swap hunk! */
    }

    /* now turn the new into the old */

    i = p_ptrn_lines + 1;
    if (tp_char[i] == '\n') {           /* account for possible blank line */
        blankline = TRUE;
        i++;
    }
    if (p_efake >= 0) {                 /* fix non-freeable ptr range */
        if (p_efake <= i)
            n = p_end - i + 1;
        else
            n = -i;
        p_efake += n;
        p_bfake += n;
    }
    for (n=0; i <= p_end; i++,n++) {
        p_line[n] = tp_line[i];
        p_Char[n] = tp_char[i];
        if (p_Char[n] == '+')
            p_Char[n] = '-';
        p_len[n] = tp_len[i];
    }
    if (blankline) {
        i = p_ptrn_lines + 1;
        p_line[n] = tp_line[i];
        p_Char[n] = tp_char[i];
        p_len[n] = tp_len[i];
        n++;
    }
    assert(p_Char[0] == '=');
    p_Char[0] = '*';
    for (s=p_line[0]; *s; s++)
        if (*s == '-')
            *s = '*';

    /* now turn the old into the new */

    assert(tp_char[0] == '*');
    tp_char[0] = '=';
    for (s=tp_line[0]; *s; s++)
        if (*s == '*')
            *s = '-';
    for (i=0; n <= p_end; i++,n++) {
        p_line[n] = tp_line[i];
        p_Char[n] = tp_char[i];
        if (p_Char[n] == '-')
            p_Char[n] = '+';
        p_len[n] = tp_len[i];
    }
    assert(i == p_ptrn_lines + 1);
    i = p_ptrn_lines;
    p_ptrn_lines = p_repl_lines;
    p_repl_lines = i;
    if (tp_line)
      free (tp_line);
    if (tp_len)
      free (tp_len);
    if (tp_char)
      free (tp_char);
    return TRUE;
}

/* Return whether file WHICH (0 = old, 1 = new) appears to nonexistent.
   Return 1 for empty, 2 for nonexistent.  */

bool
pch_says_nonexistent (which)
     int which;
{
  return p_says_nonexistent[which];
}

/* Return timestamp of patch header for file WHICH (0 = old, 1 = new),
   or -1 if there was no timestamp or an error in the timestamp.  */

time_t
pch_timestamp (which)
     int which;
{
  return p_timestamp[which];
}

/* Return the specified line position in the old file of the old context. */

LINENUM
pch_first()
{
    return p_first;
}

/* Return the number of lines of old context. */

LINENUM
pch_ptrn_lines()
{
    return p_ptrn_lines;
}

/* Return the probable line position in the new file of the first line. */

LINENUM
pch_newfirst()
{
    return p_newfirst;
}

/* Return the number of lines in the replacement text including context. */

LINENUM
pch_repl_lines()
{
    return p_repl_lines;
}

/* Return the number of lines in the whole hunk. */

LINENUM
pch_end()
{
    return p_end;
}

/* Return the number of context lines before the first changed line. */

LINENUM
pch_prefix_context ()
{
    return p_prefix_context;
}

/* Return the number of context lines after the last changed line. */

LINENUM
pch_suffix_context ()
{
    return p_suffix_context;
}

/* Return the length of a particular patch line. */

size_t
pch_line_len(line)
LINENUM line;
{
    return p_len[line];
}

/* Return the control character (+, -, *, !, etc) for a patch line. */

char
pch_char(line)
LINENUM line;
{
    return p_Char[line];
}

/* Return a pointer to a particular patch line. */

char *
pfetch(line)
LINENUM line;
{
    return p_line[line];
}

/* Output a patch line.  */

bool
pch_write_line (line, file)
     LINENUM line;
     FILE *file;
{
  bool after_newline = p_line[line][p_len[line] - 1] == '\n';
  if (! fwrite (p_line[line], sizeof (*p_line[line]), p_len[line], file))
    write_fatal ();
  return after_newline;
}

/* Return where in the patch file this hunk began, for error messages. */

LINENUM
pch_hunk_beg()
{
    return p_hunk_beg;
}

/* Apply an ed script by feeding ed itself. */

void
do_ed_script (ofp)
     FILE *ofp;
{
    static char const ed_program[] = ed_PROGRAM;

    register char *t;
    register file_offset beginning_of_this_line;
    register bool this_line_is_command = FALSE;
    register FILE *pipefp = 0;
    register size_t chars_read;

    if (!skip_rest_of_patch) {
        assert (! inerrno);
        copy_file (inname, TMPOUTNAME, instat.st_mode);
        sprintf (buf, "%s %s%s", ed_program, verbosity == VERBOSE ? "" : "- ",
                 TMPOUTNAME);
        fflush (stdout);
        pipefp = popen(buf, binary_transput ? "wb" : "w");
        if (!pipefp)
          pfatal ("can't open pipe to `%s'", buf);
    }
    for (;;) {
        beginning_of_this_line = file_tell (pfp);
        chars_read = get_line ();
        if (! chars_read) {
            next_intuit_at(beginning_of_this_line,p_input_line);
            break;
        }
        for (t = buf;  ISDIGIT (*t) || *t == ',';  t++)
          continue;
        this_line_is_command = (ISDIGIT (*buf) &&
          (*t == 'd' || *t == 'c' || *t == 'a' || *t == 'i' || *t == 's') );
        if (this_line_is_command) {
            if (pipefp)
                if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
                    write_fatal ();
            if (*t != 'd' && *t != 's') {
                while ((chars_read = get_line ()) != 0) {
                    if (pipefp)
                        if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
                            write_fatal ();
                    if (chars_read == 2  &&  strEQ (buf, ".\n"))
                        break;
                }
            }
        }
        else {
            next_intuit_at(beginning_of_this_line,p_input_line);
            break;
        }
    }
    if (!pipefp)
      return;
    if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, pipefp) == 0
        || fflush (pipefp) != 0)
      write_fatal ();
    if (pclose (pipefp) != 0)
      fatal ("%s FAILED", ed_program);

    if (ofp)
      {
        FILE *ifp = fopen (TMPOUTNAME, binary_transput ? "rb" : "r");
        int c;
        if (!ifp)
          pfatal ("can't open `%s'", TMPOUTNAME);
        while ((c = getc (ifp)) != EOF)
          if (putc (c, ofp) == EOF)
            write_fatal ();
        if (ferror (ifp) || fclose (ifp) != 0)
          read_fatal ();
      }
}