/*

 *  LibXDiff by Davide Libenzi ( File Differential Library )

 *  Copyright (C) 2003-2006 Davide Libenzi, Johannes E. Schindelin

 *

 *  This library is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU Lesser General Public

 *  License as published by the Free Software Foundation; either

 *  version 2.1 of the License, or (at your option) any later version.

 *

 *  This library 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

 *  Lesser General Public License for more details.

 *

 *  You should have received a copy of the GNU Lesser General Public

 *  License along with this library; if not, see

 *  <http://www.gnu.org/licenses/>.

 *

 *  Davide Libenzi <davidel@xmailserver.org>

 *

 */

#include "xinclude.h"

typedef struct s_xdmerge {

  struct s_xdmerge *next;

  /*

   * 0 = conflict,

   * 1 = no conflict, take first,

   * 2 = no conflict, take second.

   * 3 = no conflict, take both.

   */

  int mode;

  /*

   * These point at the respective postimages.  E.g. <i1,chg1> is

   * how side #1 wants to change the common ancestor; if there is no

   * overlap, lines before i1 in the postimage of side #1 appear

   * in the merge result as a region touched by neither side.

   */

  long i1, i2;

  long chg1, chg2;

  /*

   * These point at the preimage; of course there is just one

   * preimage, that is from the shared common ancestor.

   */

  long i0;

  long chg0;

} xdmerge_t;

static int xdl_append_merge(xdmerge_t **merge, int mode,

          long i0, long chg0,

          long i1, long chg1,

          long i2, long chg2)

{

  xdmerge_t *m = *merge;

  if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {

    if (mode != m->mode)

      m->mode = 0;

    m->chg0 = i0 + chg0 - m->i0;

    m->chg1 = i1 + chg1 - m->i1;

    m->chg2 = i2 + chg2 - m->i2;

  } else {

    m = xdl_malloc(sizeof(xdmerge_t));

    if (!m)

      return -1;

    m->next = NULL;

    m->mode = mode;

    m->i0 = i0;

    m->chg0 = chg0;

    m->i1 = i1;

    m->chg1 = chg1;

    m->i2 = i2;

    m->chg2 = chg2;

    if (*merge)

      (*merge)->next = m;

    *merge = m;

  }

  return 0;

}

static int xdl_cleanup_merge(xdmerge_t *c)

{

  int count = 0;

  xdmerge_t *next_c;

  /* were there conflicts? */

  for (; c; c = next_c) {

    if (c->mode == 0)

      count++;

    next_c = c->next;

    free(c);

  }

  return count;

}

static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,

    int line_count, long flags)

{

  int i;

  xrecord_t *rec1 = xe1->xdf2.recs + i1;

  xrecord_t *rec2 = xe2->xdf2.recs + i2;

  for (i = 0; i < line_count; i++) {

    int result = xdl_recmatch((const char *)rec1[i].ptr, (long)rec1[i].size,

      (const char *)rec2[i].ptr, (long)rec2[i].size, flags);

    if (!result)

      return -1;

  }

  return 0;

}

static size_t xdl_recs_copy_0(int use_orig, xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest)

{

  xrecord_t *recs;

  size_t size = 0;

  recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i;

  if (count < 1)

    return 0;

  for (i = 0; i < count; size = st_add(size, recs[i++].size))

    if (dest)

      memcpy(dest + size, recs[i].ptr, recs[i].size);

  if (add_nl) {

    i = (int)recs[count - 1].size;

    if (i == 0 || recs[count - 1].ptr[i - 1] != '\n') {

      if (needs_cr) {

        if (dest)

          dest[size] = '\r';

        size = st_add(size, 1);

      }

      if (dest)

        dest[size] = '\n';

      size = st_add(size, 1);

    }

  }

  return size;

}

static size_t xdl_recs_copy(xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest)

{

  return xdl_recs_copy_0(0, xe, i, count, needs_cr, add_nl, dest);

}

static size_t xdl_orig_copy(xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest)

{

  return xdl_recs_copy_0(1, xe, i, count, needs_cr, add_nl, dest);

}

/*

 * Returns 1 if the i'th line ends in CR/LF (if it is the last line and

 * has no eol, the preceding line, if any), 0 if it ends in LF-only, and

 * -1 if the line ending cannot be determined.

 */

static int is_eol_crlf(xdfile_t *file, int i)

{

  size_t size;

  if (i < (long)file->nrec - 1)

    /* All lines before the last *must* end in LF */

    return (size = file->recs[i].size) > 1 &&

      file->recs[i].ptr[size - 2] == '\r';

  if (!file->nrec)

    /* Cannot determine eol style from empty file */

    return -1;

  if ((size = file->recs[i].size) &&

      file->recs[i].ptr[size - 1] == '\n')

    /* Last line; ends in LF; Is it CR/LF? */

    return size > 1 &&

      file->recs[i].ptr[size - 2] == '\r';

  if (!i)

    /* The only line has no eol */

    return -1;

  /* Determine eol from second-to-last line */

  return (size = file->recs[i - 1].size) > 1 &&

    file->recs[i - 1].ptr[size - 2] == '\r';

}

static int is_cr_needed(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m)

{

  int needs_cr;

  /* Match post-images' preceding, or first, lines' end-of-line style */

  needs_cr = is_eol_crlf(&xe1->xdf2, m->i1 ? m->i1 - 1 : 0);

  if (needs_cr)

    needs_cr = is_eol_crlf(&xe2->xdf2, m->i2 ? m->i2 - 1 : 0);

  /* Look at pre-image's first line, unless we already settled on LF */

  if (needs_cr)

    needs_cr = is_eol_crlf(&xe1->xdf1, 0);

  /* If still undecided, use LF-only */

  return needs_cr < 0 ? 0 : needs_cr;

}

static size_t fill_conflict_hunk(xdfenv_t *xe1, const char *name1,

         xdfenv_t *xe2, const char *name2,

         const char *name3,

         size_t size, int i, int style,

         xdmerge_t *m, char *dest, int marker_size)

{

  int marker1_size = (name1 && *name1 ? strlen(name1) + 1 : 0);

  int marker2_size = (name2 && *name2 ? strlen(name2) + 1 : 0);

  int marker3_size = (name3 && *name3 ? strlen(name3) + 1 : 0);

  int needs_cr = is_cr_needed(xe1, xe2, m);

  if (marker_size <= 0)

    marker_size = DEFAULT_CONFLICT_MARKER_SIZE;

  /* Before conflicting part */

  size = st_add(size, xdl_recs_copy(xe1, i, m->i1 - i, 0, 0,

            dest ? dest + size : NULL));

  if (!dest) {

    size = st_add5(size, marker_size, 1, needs_cr, marker1_size);

  } else {

    memset(dest + size, '<', marker_size);

    size += marker_size;

    if (marker1_size) {

      dest[size] = ' ';

      memcpy(dest + size + 1, name1, marker1_size - 1);

      size += marker1_size;

    }

    if (needs_cr)

      dest[size++] = '\r';

    dest[size++] = '\n';

  }

  /* Postimage from side #1 */

  size = st_add(size, xdl_recs_copy(xe1, m->i1, m->chg1, needs_cr, 1,

            dest ? dest + size : NULL));

  if (style == XDL_MERGE_DIFF3 || style == XDL_MERGE_ZEALOUS_DIFF3) {

    /* Shared preimage */

    if (!dest) {

      size = st_add5(size, marker_size, 1, needs_cr, marker3_size);

    } else {

      memset(dest + size, '|', marker_size);

      size += marker_size;

      if (marker3_size) {

        dest[size] = ' ';

        memcpy(dest + size + 1, name3, marker3_size - 1);

        size += marker3_size;

      }

      if (needs_cr)

        dest[size++] = '\r';

      dest[size++] = '\n';

    }

    size = st_add(size, xdl_orig_copy(xe1, m->i0, m->chg0, needs_cr, 1,

              dest ? dest + size : NULL));

  }

  if (!dest) {

    size = st_add4(size, marker_size, 1, needs_cr);

  } else {

    memset(dest + size, '=', marker_size);

    size += marker_size;

    if (needs_cr)

      dest[size++] = '\r';

    dest[size++] = '\n';

  }

  /* Postimage from side #2 */

  size = st_add(size, xdl_recs_copy(xe2, m->i2, m->chg2, needs_cr, 1,

            dest ? dest + size : NULL));

  if (!dest) {

    size = st_add5(size, marker_size, 1, needs_cr, marker2_size);

  } else {

    memset(dest + size, '>', marker_size);

    size += marker_size;

    if (marker2_size) {

      dest[size] = ' ';

      memcpy(dest + size + 1, name2, marker2_size - 1);

      size += marker2_size;

    }

    if (needs_cr)

      dest[size++] = '\r';

    dest[size++] = '\n';

  }

  return size;

}

static size_t xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,

            xdfenv_t *xe2, const char *name2,

            const char *ancestor_name,

            int favor,

            xdmerge_t *m, char *dest, int style,

            int marker_size)

{

  size_t size;

  int i;

  for (size = i = 0; m; m = m->next) {

    if (favor && !m->mode)

      m->mode = favor;

    if (m->mode == 0)

      size = fill_conflict_hunk(xe1, name1, xe2, name2,

              ancestor_name,

              size, i, style, m, dest,

              marker_size);

    else if (m->mode & 3) {

      /* Before conflicting part */

      size = st_add(size, xdl_recs_copy(xe1, i, m->i1 - i, 0, 0,

                dest ? dest + size : NULL));

      /* Postimage from side #1 */

      if (m->mode & 1) {

        int needs_cr = is_cr_needed(xe1, xe2, m);

        size = st_add(size, xdl_recs_copy(xe1, m->i1, m->chg1, needs_cr, (m->mode & 2),

                  dest ? dest + size : NULL));

      }

      /* Postimage from side #2 */

      if (m->mode & 2)

        size = st_add(size, xdl_recs_copy(xe2, m->i2, m->chg2, 0, 0,

                  dest ? dest + size : NULL));

    } else

      continue;

    i = m->i1 + m->chg1;

  }

  size = st_add(size, xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0, 0,

            dest ? dest + size : NULL));

  return size;

}

static int recmatch(xrecord_t *rec1, xrecord_t *rec2, unsigned long flags)

{

  return xdl_recmatch((const char *)rec1->ptr, (long)rec1->size,

          (const char *)rec2->ptr, (long)rec2->size, flags);

}

/*

 * Remove any common lines from the beginning and end of the conflicted region.

 */

static void xdl_refine_zdiff3_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,

    xpparam_t const *xpp)

{

  xrecord_t *rec1 = xe1->xdf2.recs, *rec2 = xe2->xdf2.recs;

  for (; m; m = m->next) {

    /* let's handle just the conflicts */

    if (m->mode)

      continue;

    while(m->chg1 && m->chg2 &&

          recmatch(&rec1[m->i1], &rec2[m->i2], xpp->flags)) {

      m->chg1--;

      m->chg2--;

      m->i1++;

      m->i2++;

    }

    while (m->chg1 && m->chg2 &&

           recmatch(&rec1[m->i1 + m->chg1 - 1],

        &rec2[m->i2 + m->chg2 - 1], xpp->flags)) {

      m->chg1--;

      m->chg2--;

    }

  }

}

/*

 * Sometimes, changes are not quite identical, but differ in only a few

 * lines. Try hard to show only these few lines as conflicting.

 */

static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,

    xpparam_t const *xpp)

{

  for (; m; m = m->next) {

    mmfile_t t1, t2;

    xdfenv_t xe;

    xdchange_t *xscr, *x;

    int i1 = m->i1, i2 = m->i2;

    /* let's handle just the conflicts */

    if (m->mode)

      continue;

    /* no sense refining a conflict when one side is empty */

    if (m->chg1 == 0 || m->chg2 == 0)

      continue;

    /*

     * This probably does not work outside git, since

     * we have a very simple mmfile structure.

     */

    t1.ptr = (char *)xe1->xdf2.recs[m->i1].ptr;

    t1.size = (char *)xe1->xdf2.recs[m->i1 + m->chg1 - 1].ptr

      + xe1->xdf2.recs[m->i1 + m->chg1 - 1].size - t1.ptr;

    t2.ptr = (char *)xe2->xdf2.recs[m->i2].ptr;

    t2.size = (char *)xe2->xdf2.recs[m->i2 + m->chg2 - 1].ptr

      + xe2->xdf2.recs[m->i2 + m->chg2 - 1].size - t2.ptr;

    if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)

      return -1;

    if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||

        xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||

        xdl_build_script(&xe, &xscr) < 0) {

      xdl_free_env(&xe);

      return -1;

    }

    if (!xscr) {

      /* If this happens, the changes are identical. */

      xdl_free_env(&xe);

      m->mode = 4;

      continue;

    }

    x = xscr;

    m->i1 = xscr->i1 + i1;

    m->chg1 = xscr->chg1;

    m->i2 = xscr->i2 + i2;

    m->chg2 = xscr->chg2;

    while (xscr->next) {

      xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));

      if (!m2) {

        xdl_free_env(&xe);

        xdl_free_script(x);

        return -1;

      }

      xscr = xscr->next;

      m2->next = m->next;

      m->next = m2;

      m = m2;

      m->mode = 0;

      m->i1 = xscr->i1 + i1;

      m->chg1 = xscr->chg1;

      m->i2 = xscr->i2 + i2;

      m->chg2 = xscr->chg2;

    }

    xdl_free_env(&xe);

    xdl_free_script(x);

  }

  return 0;

}

static int line_contains_alnum(const char *ptr, long size)

{

  while (size--)

    if (isalnum((unsigned char)*(ptr++)))

      return 1;

  return 0;

}

static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)

{

  for (; chg; chg--, i++)

    if (line_contains_alnum((const char *)xe->xdf2.recs[i].ptr,

        (long)xe->xdf2.recs[i].size))

      return 1;

  return 0;

}

/*

 * This function merges m and m->next, marking everything between those hunks

 * as conflicting, too.

 */

static void xdl_merge_two_conflicts(xdmerge_t *m)

{

  xdmerge_t *next_m = m->next;

  m->chg1 = next_m->i1 + next_m->chg1 - m->i1;

  m->chg2 = next_m->i2 + next_m->chg2 - m->i2;

  m->next = next_m->next;

  free(next_m);

}

/*

 * If there are less than 3 non-conflicting lines between conflicts,

 * it appears simpler -- because it takes up less (or as many) lines --

 * if the lines are moved into the conflicts.

 */

static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,

              int simplify_if_no_alnum)

{

  int result = 0;

  if (!m)

    return result;

  for (;;) {

    xdmerge_t *next_m = m->next;

    int begin, end;

    if (!next_m)

      return result;

    begin = m->i1 + m->chg1;

    end = next_m->i1;

    if (m->mode != 0 || next_m->mode != 0 ||

        (end - begin > 3 &&

         (!simplify_if_no_alnum ||

          lines_contain_alnum(xe1, begin, end - begin)))) {

      m = next_m;

    } else {

      result++;

      xdl_merge_two_conflicts(m);

    }

  }

}

/*

 * level == 0: mark all overlapping changes as conflict

 * level == 1: mark overlapping changes as conflict only if not identical

 * level == 2: analyze non-identical changes for minimal conflict set

 * level == 3: analyze non-identical changes for minimal conflict set, but

 *             treat hunks not containing any letter or number as conflicting

 *

 * returns < 0 on error, == 0 for no conflicts, else number of conflicts

 */

static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1,

    xdfenv_t *xe2, xdchange_t *xscr2,

    xmparam_t const *xmp, mmfile_t *result)

{

  xdmerge_t *changes, *c;

  xpparam_t const *xpp = &xmp->xpp;

  const char *const ancestor_name = xmp->ancestor;

  const char *const name1 = xmp->file1;

  const char *const name2 = xmp->file2;

  int i0, i1, i2, chg0, chg1, chg2;

  int level = xmp->level;

  int style = xmp->style;

  int favor = xmp->favor;

  /*

   * XDL_MERGE_DIFF3 does not attempt to refine conflicts by looking

   * at common areas of sides 1 & 2, because the base (side 0) does

   * not match and is being shown.  Similarly, simplification of

   * non-conflicts is also skipped due to the skipping of conflict

   * refinement.

   *

   * XDL_MERGE_ZEALOUS_DIFF3, on the other hand, will attempt to

   * refine conflicts looking for common areas of sides 1 & 2.

   * However, since the base is being shown and does not match,

   * it will only look for common areas at the beginning or end

   * of the conflict block.  Since XDL_MERGE_ZEALOUS_DIFF3's

   * conflict refinement is much more limited in this fashion, the

   * conflict simplification will be skipped.

   */

  if (style == XDL_MERGE_DIFF3 || style == XDL_MERGE_ZEALOUS_DIFF3) {

    /*

     * "diff3 -m" output does not make sense for anything

     * more aggressive than XDL_MERGE_EAGER.

     */

    if (XDL_MERGE_EAGER < level)

      level = XDL_MERGE_EAGER;

  }

  c = changes = NULL;

  while (xscr1 && xscr2) {

    if (!changes)

      changes = c;

    if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {

      i0 = xscr1->i1;

      i1 = xscr1->i2;

      i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;

      chg0 = xscr1->chg1;

      chg1 = xscr1->chg2;

      chg2 = xscr1->chg1;

      if (xdl_append_merge(&c, 1,

               i0, chg0, i1, chg1, i2, chg2)) {

        xdl_cleanup_merge(changes);

        return -1;

      }

      xscr1 = xscr1->next;

      continue;

    }

    if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {

      i0 = xscr2->i1;

      i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;

      i2 = xscr2->i2;

      chg0 = xscr2->chg1;

      chg1 = xscr2->chg1;

      chg2 = xscr2->chg2;

      if (xdl_append_merge(&c, 2,

               i0, chg0, i1, chg1, i2, chg2)) {

        xdl_cleanup_merge(changes);

        return -1;

      }

      xscr2 = xscr2->next;

      continue;

    }

    if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 ||

        xscr1->chg1 != xscr2->chg1 ||

        xscr1->chg2 != xscr2->chg2 ||

        xdl_merge_cmp_lines(xe1, xscr1->i2,

          xe2, xscr2->i2,

          xscr1->chg2, xpp->flags)) {

      /* conflict */

      int off = xscr1->i1 - xscr2->i1;

      int ffo = off + xscr1->chg1 - xscr2->chg1;

      i0 = xscr1->i1;

      i1 = xscr1->i2;

      i2 = xscr2->i2;

      if (off > 0) {

        i0 -= off;

        i1 -= off;

      }

      else

        i2 += off;

      chg0 = xscr1->i1 + xscr1->chg1 - i0;

      chg1 = xscr1->i2 + xscr1->chg2 - i1;

      chg2 = xscr2->i2 + xscr2->chg2 - i2;

      if (ffo < 0) {

        chg0 -= ffo;

        chg1 -= ffo;

      } else

        chg2 += ffo;

      if (xdl_append_merge(&c, 0,

               i0, chg0, i1, chg1, i2, chg2)) {

        xdl_cleanup_merge(changes);

        return -1;

      }

    }

    i1 = xscr1->i1 + xscr1->chg1;

    i2 = xscr2->i1 + xscr2->chg1;

    if (i1 >= i2)

      xscr2 = xscr2->next;

    if (i2 >= i1)

      xscr1 = xscr1->next;

  }

  while (xscr1) {

    if (!changes)

      changes = c;

    i0 = xscr1->i1;

    i1 = xscr1->i2;

    i2 = xscr1->i1 + (long)xe2->xdf2.nrec - (long)xe2->xdf1.nrec;

    chg0 = xscr1->chg1;

    chg1 = xscr1->chg2;

    chg2 = xscr1->chg1;

    if (xdl_append_merge(&c, 1,

             i0, chg0, i1, chg1, i2, chg2)) {

      xdl_cleanup_merge(changes);

      return -1;

    }

    xscr1 = xscr1->next;

  }

  while (xscr2) {

    if (!changes)

      changes = c;

    i0 = xscr2->i1;

    i1 = xscr2->i1 + (long)xe1->xdf2.nrec - (long)xe1->xdf1.nrec;

    i2 = xscr2->i2;

    chg0 = xscr2->chg1;

    chg1 = xscr2->chg1;

    chg2 = xscr2->chg2;

    if (xdl_append_merge(&c, 2,

             i0, chg0, i1, chg1, i2, chg2)) {

      xdl_cleanup_merge(changes);

      return -1;

    }

    xscr2 = xscr2->next;

  }

  if (!changes)

    changes = c;

  /* refine conflicts */

  if (style == XDL_MERGE_ZEALOUS_DIFF3) {

    xdl_refine_zdiff3_conflicts(xe1, xe2, changes, xpp);

  } else if (XDL_MERGE_ZEALOUS <= level &&

       (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||

        xdl_simplify_non_conflicts(xe1, changes,

                 XDL_MERGE_ZEALOUS < level) < 0)) {

    xdl_cleanup_merge(changes);

    return -1;

  }

  /* output */

  if (result) {

    int marker_size = xmp->marker_size;

    size_t size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,

                ancestor_name,

                favor, changes, NULL, style,

                marker_size);

    if (size > LONG_MAX) {

      xdl_cleanup_merge(changes);

      return -1;

    }

    result->ptr = xdl_malloc(size);

    if (!result->ptr) {

      xdl_cleanup_merge(changes);

      return -1;

    }

    result->size = size;

    xdl_fill_merge_buffer(xe1, name1, xe2, name2,

              ancestor_name, favor, changes,

              result->ptr, style, marker_size);

  }

  return xdl_cleanup_merge(changes);

}

int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,

    xmparam_t const *xmp, mmfile_t *result)

{

  xdchange_t *xscr1 = NULL, *xscr2 = NULL;

  xdfenv_t xe1, xe2;

  int status = -1;

  xpparam_t const *xpp = &xmp->xpp;

  result->ptr = NULL;

  result->size = 0;

  if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0)

    return -1;

  if (xdl_do_diff(orig, mf2, xpp, &xe2) < 0)

    goto free_xe1; /* avoid double free of xe2 */

  if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||

      xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||

      xdl_build_script(&xe1, &xscr1) < 0)

    goto out;

  if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||

      xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||

      xdl_build_script(&xe2, &xscr2) < 0)

    goto out;

  if (!xscr1) {

    result->ptr = xdl_malloc(mf2->size);

    if (!result->ptr)

      goto out;

    status = 0;

    memcpy(result->ptr, mf2->ptr, mf2->size);

    result->size = mf2->size;

  } else if (!xscr2) {

    result->ptr = xdl_malloc(mf1->size);

    if (!result->ptr)

      goto out;

    status = 0;

    memcpy(result->ptr, mf1->ptr, mf1->size);

    result->size = mf1->size;

  } else {

    status = xdl_do_merge(&xe1, xscr1,

              &xe2, xscr2,

              xmp, result);

  }

 out:

  xdl_free_script(xscr1);

  xdl_free_script(xscr2);

  xdl_free_env(&xe2);

 free_xe1:

  xdl_free_env(&xe1);

  return status;

}