thodg/libgit2/src/xdiff/xmerge.c

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• Hash : f3b3e543
  Author :
  Date : 2019-08-08T11:34:01
  

  xdiff: catch memory allocation errors The xdiff code contains multiple call sites where the results of `xdl_malloc` are not being checked for memory allocation errors. Add checks to fix possible segfaults due to `NULL` pointer accesses.

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• src/xdiff/xmerge.c

• /*
   *  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(rec1[i]->ptr, rec1[i]->size,
  			rec2[i]->ptr, rec2[i]->size, flags);
  		if (!result)
  			return -1;
  	}
  	return 0;
  }
  
  static int xdl_recs_copy_0(size_t *out, 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;
  
  	*out = 0;
  
  	recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i;
  
  	if (count < 1)
  		return 0;
  
  	for (i = 0; i < count; ) {
  		if (dest)
  			memcpy(dest + size, recs[i]->ptr, recs[i]->size);
  
  		GIT_ERROR_CHECK_ALLOC_ADD(&size, size, recs[i++]->size);
  	}
  
  	if (add_nl) {
  		i = recs[count - 1]->size;
  		if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
  			if (needs_cr) {
  				if (dest)
  					dest[size] = '\r';
  				GIT_ERROR_CHECK_ALLOC_ADD(&size, size, 1);
  			}
  
  			if (dest)
  				dest[size] = '\n';
  
  			GIT_ERROR_CHECK_ALLOC_ADD(&size, size, 1);
  		}
  	}
  
  	*out = size;
  	return 0;
  }
  
  static int xdl_recs_copy(size_t *out, xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest)
  {
  	return xdl_recs_copy_0(out, 0, xe, i, count, needs_cr, add_nl, dest);
  }
  
  static int xdl_orig_copy(size_t *out, xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest)
  {
  	return xdl_recs_copy_0(out, 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)
  {
  	long size;
  
  	if (i < 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 int fill_conflict_hunk(size_t *out, 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 ? (int)strlen(name1) + 1 : 0);
  	int marker2_size = (name2 ? (int)strlen(name2) + 1 : 0);
  	int marker3_size = (name3 ? (int)strlen(name3) + 1 : 0);
  	int needs_cr = is_cr_needed(xe1, xe2, m);
  	size_t copied;
  
  	*out = 0;
  
  	if (marker_size <= 0)
  		marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
  
  	/* Before conflicting part */
  	if (xdl_recs_copy(&copied, xe1, i, m->i1 - i, 0, 0,
  			      dest ? dest + size : NULL) < 0)
  		return -1;
  
  	GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied);
  
  	if (!dest) {
  		GIT_ERROR_CHECK_ALLOC_ADD5(&size, 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 */
  	if (xdl_recs_copy(&copied, xe1, m->i1, m->chg1, needs_cr, 1,
  			      dest ? dest + size : NULL) < 0)
  		return -1;
  
  	GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied);
  
  	if (style == XDL_MERGE_DIFF3) {
  		/* Shared preimage */
  		if (!dest) {
  			GIT_ERROR_CHECK_ALLOC_ADD5(&size, 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';
  		}
  
  		if (xdl_orig_copy(&copied, xe1, m->i0, m->chg0, needs_cr, 1,
  				      dest ? dest + size : NULL) < 0)
  			return -1;
  		GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied);
  	}
  
  	if (!dest) {
  		GIT_ERROR_CHECK_ALLOC_ADD4(&size, 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 */
  
  	if (xdl_recs_copy(&copied, xe2, m->i2, m->chg2, needs_cr, 1,
  			      dest ? dest + size : NULL) < 0)
  		return -1;
  	GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied);
  
  	if (!dest) {
  		GIT_ERROR_CHECK_ALLOC_ADD5(&size, 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';
  	}
  
  	*out = size;
  	return 0;
  }
  
  static int xdl_fill_merge_buffer(size_t *out,
  				 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, copied;
  	int i;
  
  	*out = 0;
  
  	for (size = i = 0; m; m = m->next) {
  		if (favor && !m->mode)
  			m->mode = favor;
  
  		if (m->mode == 0) {
  			if (fill_conflict_hunk(&size, xe1, name1, xe2, name2,
  						  ancestor_name,
  						  size, i, style, m, dest,
  						  marker_size) < 0)
  				return -1;
  		}
  		else if (m->mode & 3) {
  			/* Before conflicting part */
  			if (xdl_recs_copy(&copied, xe1, i, m->i1 - i, 0, 0,
  					      dest ? dest + size : NULL) < 0)
  				return -1;
  			GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied);
  
  			/* Postimage from side #1 */
  			if (m->mode & 1) {
  				int needs_cr = is_cr_needed(xe1, xe2, m);
  
  				if (xdl_recs_copy(&copied, xe1, m->i1, m->chg1, needs_cr, (m->mode & 2),
  						      dest ? dest + size : NULL) < 0)
  					return -1;
  				GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied);
  			}
  
  			/* Postimage from side #2 */
  			if (m->mode & 2) {
  				if (xdl_recs_copy(&copied, xe2, m->i2, m->chg2, 0, 0,
  						      dest ? dest + size : NULL) < 0)
  					return -1;
  				GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied);
  			}
  		} else
  			continue;
  		i = m->i1 + m->chg1;
  	}
  
  	if (xdl_recs_copy(&copied, xe1, i, xe1->xdf2.nrec - i, 0, 0,
  			      dest ? dest + size : NULL) < 0)
  		return -1;
  	GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied);
  
  	*out = size;
  	return 0;
  }
  
  /*
   * 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 = 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 = 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(xe->xdf2.recs[i]->ptr,
  				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, mmbuffer_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;
  
  	if (style == XDL_MERGE_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 + xe2->xdf2.nrec - 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 + xe1->xdf2.nrec - 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 (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;
  
  		if (xdl_fill_merge_buffer(&size, xe1, name1, xe2, name2,
  						 ancestor_name,
  						 favor, changes, NULL, style,
  						 marker_size) < 0)
  			return -1;
  
  		result->ptr = xdl_malloc(size);
  		if (!result->ptr) {
  			xdl_cleanup_merge(changes);
  			return -1;
  		}
  		result->size = size;
  		if (xdl_fill_merge_buffer(&size, xe1, name1, xe2, name2,
  				      ancestor_name, favor, changes,
  				      result->ptr, style, marker_size) < 0)
  			return -1;
  	}
  	return xdl_cleanup_merge(changes);
  }
  
  int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
  		xmparam_t const *xmp, mmbuffer_t *result)
  {
  	xdchange_t *xscr1, *xscr2;
  	xdfenv_t xe1, xe2;
  	int status;
  	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) {
  		xdl_free_env(&xe1);
  		return -1;
  	}
  	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) {
  		xdl_free_env(&xe1);
  		return -1;
  	}
  	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) {
  		xdl_free_script(xscr1);
  		xdl_free_env(&xe1);
  		xdl_free_env(&xe2);
  		return -1;
  	}
  	status = 0;
  	if (!xscr1) {
  		result->ptr = xdl_malloc(mf2->size);
  		if (!result->ptr) {
  			xdl_free_script(xscr2);
  			xdl_free_env(&xe1);
  			xdl_free_env(&xe2);
  			return -1;
  		}
  		memcpy(result->ptr, mf2->ptr, mf2->size);
  		result->size = mf2->size;
  	} else if (!xscr2) {
  		result->ptr = xdl_malloc(mf1->size);
  		if (!result->ptr) {
  			xdl_free_script(xscr1);
  			xdl_free_env(&xe1);
  			xdl_free_env(&xe2);
  			return -1;
  		}
  		memcpy(result->ptr, mf1->ptr, mf1->size);
  		result->size = mf1->size;
  	} else {
  		status = xdl_do_merge(&xe1, xscr1,
  				      &xe2, xscr2,
  				      xmp, result);
  	}
  	xdl_free_script(xscr1);
  	xdl_free_script(xscr2);
  
  	xdl_free_env(&xe1);
  	xdl_free_env(&xe2);
  
  	return status;
  }
  

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