Add libxdiff library

xdiff/xmerge.c

Index: xdiff/xmerge.c
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
new file mode 100644
index 0000000000000000000000000000000000000000..f338ad6c757cda29a052960a504715c062ab5dda
--- /dev/null
+++ b/xdiff/xmerge.c
@@ -0,0 +1,686 @@
+/*
+ *  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, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  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(int use_orig, xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest)
+{
+	xrecord_t **recs;
+	int size = 0;
+
+	recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i;
+
+	if (count < 1)
+		return 0;
+
+	for (i = 0; i < count; size += recs[i++]->size)
+		if (dest)
+			memcpy(dest + size, recs[i]->ptr, 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';
+				size++;
+			}
+
+			if (dest)
+				dest[size] = '\n';
+			size++;
+		}
+	}
+	return size;
+}
+
+static int 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 int 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)
+{
+	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(xdfenv_t *xe1, const char *name1,
+			      xdfenv_t *xe2, const char *name2,
+			      const char *name3,
+			      int size, int i, int style,
+			      xdmerge_t *m, char *dest, int marker_size)
+{
+	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
+	int marker3_size = (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 += xdl_recs_copy(xe1, i, m->i1 - i, 0, 0,
+			      dest ? dest + size : NULL);
+
+	if (!dest) {
+		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 += xdl_recs_copy(xe1, m->i1, m->chg1, needs_cr, 1,
+			      dest ? dest + size : NULL);
+
+	if (style == XDL_MERGE_DIFF3) {
+		/* Shared preimage */
+		if (!dest) {
+			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 += xdl_orig_copy(xe1, m->i0, m->chg0, needs_cr, 1,
+				      dest ? dest + size : NULL);
+	}
+
+	if (!dest) {
+		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 += xdl_recs_copy(xe2, m->i2, m->chg2, needs_cr, 1,
+			      dest ? dest + size : NULL);
+	if (!dest) {
+		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 int 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)
+{
+	int size, 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 += 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 += 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 += xdl_recs_copy(xe2, m->i2, m->chg2, 0, 0,
+						      dest ? dest + size : NULL);
+		} else
+			continue;
+		i = m->i1 + m->chg1;
+	}
+	size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0, 0,
+			      dest ? dest + size : NULL);
+	return size;
+}
+
+/*
+ * 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;
+		int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
+						 ancestor_name,
+						 favor, changes, NULL, style,
+						 marker_size);
+		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, 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);
+		memcpy(result->ptr, mf2->ptr, mf2->size);
+		result->size = mf2->size;
+	} else if (!xscr2) {
+		result->ptr = xdl_malloc(mf1->size);
+		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;
+}