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The function xdl_refine_conflicts() tries to break down huge conflicts by doing a diff on the conflicting regions. However, this does not make sense when one side is empty. Worse, when one side is not only empty, but after EOF, the code accessed unmapped memory. Noticed by Luben Tuikov, Shawn Pearce and Alexandre Julliard, the latter providing a test case. Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Junio C Hamano <junkio@cox.net>
424 lines
10 KiB
C
424 lines
10 KiB
C
/*
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* LibXDiff by Davide Libenzi ( File Differential Library )
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* Copyright (C) 2003-2006 Davide Libenzi, Johannes E. Schindelin
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Davide Libenzi <davidel@xmailserver.org>
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*
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*/
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#include "xinclude.h"
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typedef struct s_xdmerge {
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struct s_xdmerge *next;
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/*
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* 0 = conflict,
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* 1 = no conflict, take first,
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* 2 = no conflict, take second.
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*/
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int mode;
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long i1, i2;
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long chg1, chg2;
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} xdmerge_t;
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static int xdl_append_merge(xdmerge_t **merge, int mode,
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long i1, long chg1, long i2, long chg2)
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{
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xdmerge_t *m = *merge;
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if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
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if (mode != m->mode)
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m->mode = 0;
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m->chg1 = i1 + chg1 - m->i1;
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m->chg2 = i2 + chg2 - m->i2;
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} else {
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m = xdl_malloc(sizeof(xdmerge_t));
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if (!m)
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return -1;
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m->next = NULL;
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m->mode = mode;
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m->i1 = i1;
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m->chg1 = chg1;
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m->i2 = i2;
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m->chg2 = chg2;
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if (*merge)
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(*merge)->next = m;
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*merge = m;
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}
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return 0;
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}
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static int xdl_cleanup_merge(xdmerge_t *c)
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{
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int count = 0;
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xdmerge_t *next_c;
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/* were there conflicts? */
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for (; c; c = next_c) {
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if (c->mode == 0)
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count++;
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next_c = c->next;
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free(c);
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}
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return count;
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}
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static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
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int line_count, long flags)
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{
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int i;
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xrecord_t **rec1 = xe1->xdf2.recs + i1;
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xrecord_t **rec2 = xe2->xdf2.recs + i2;
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for (i = 0; i < line_count; i++) {
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int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
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rec2[i]->ptr, rec2[i]->size, flags);
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if (!result)
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return -1;
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}
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return 0;
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}
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static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
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{
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xrecord_t **recs = xe->xdf2.recs + i;
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int size = 0;
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if (count < 1)
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return 0;
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for (i = 0; i < count; size += recs[i++]->size)
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if (dest)
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memcpy(dest + size, recs[i]->ptr, recs[i]->size);
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if (add_nl) {
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i = recs[count - 1]->size;
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if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
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if (dest)
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dest[size] = '\n';
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size++;
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}
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}
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return size;
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}
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static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
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xdfenv_t *xe2, const char *name2, xdmerge_t *m, char *dest)
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{
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const int marker_size = 7;
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int marker1_size = (name1 ? strlen(name1) + 1 : 0);
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int marker2_size = (name2 ? strlen(name2) + 1 : 0);
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int conflict_marker_size = 3 * (marker_size + 1)
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+ marker1_size + marker2_size;
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int size, i1, j;
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for (size = i1 = 0; m; m = m->next) {
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if (m->mode == 0) {
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size += xdl_recs_copy(xe1, i1, m->i1 - i1, 0,
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dest ? dest + size : NULL);
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if (dest) {
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for (j = 0; j < marker_size; j++)
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dest[size++] = '<';
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if (marker1_size) {
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dest[size] = ' ';
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memcpy(dest + size + 1, name1,
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marker1_size - 1);
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size += marker1_size;
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}
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dest[size++] = '\n';
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} else
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size += conflict_marker_size;
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size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
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dest ? dest + size : NULL);
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if (dest) {
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for (j = 0; j < marker_size; j++)
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dest[size++] = '=';
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dest[size++] = '\n';
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}
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size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
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dest ? dest + size : NULL);
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if (dest) {
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for (j = 0; j < marker_size; j++)
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dest[size++] = '>';
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if (marker2_size) {
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dest[size] = ' ';
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memcpy(dest + size + 1, name2,
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marker2_size - 1);
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size += marker2_size;
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}
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dest[size++] = '\n';
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}
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} else if (m->mode == 1)
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size += xdl_recs_copy(xe1, i1, m->i1 + m->chg1 - i1, 0,
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dest ? dest + size : NULL);
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else if (m->mode == 2)
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size += xdl_recs_copy(xe2, m->i2 - m->i1 + i1,
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m->i1 + m->chg2 - i1, 0,
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dest ? dest + size : NULL);
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i1 = m->i1 + m->chg1;
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}
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size += xdl_recs_copy(xe1, i1, xe1->xdf2.nrec - i1, 0,
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dest ? dest + size : NULL);
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return size;
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}
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/*
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* Sometimes, changes are not quite identical, but differ in only a few
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* lines. Try hard to show only these few lines as conflicting.
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*/
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static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
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xpparam_t const *xpp)
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{
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for (; m; m = m->next) {
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mmfile_t t1, t2;
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xdfenv_t xe;
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xdchange_t *xscr, *x;
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int i1 = m->i1, i2 = m->i2;
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/* let's handle just the conflicts */
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if (m->mode)
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continue;
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/* no sense refining a conflict when one side is empty */
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if (m->chg1 == 0 || m->chg2 == 0)
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continue;
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/*
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* This probably does not work outside git, since
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* we have a very simple mmfile structure.
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*/
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t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
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t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
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+ xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
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t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
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t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
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+ xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
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if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
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return -1;
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if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
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xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
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xdl_build_script(&xe, &xscr) < 0) {
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xdl_free_env(&xe);
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return -1;
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}
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if (!xscr) {
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/* If this happens, it's a bug. */
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xdl_free_env(&xe);
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return -2;
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}
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x = xscr;
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m->i1 = xscr->i1 + i1;
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m->chg1 = xscr->chg1;
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m->i2 = xscr->i2 + i2;
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m->chg2 = xscr->chg2;
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while (xscr->next) {
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xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
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if (!m2) {
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xdl_free_env(&xe);
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xdl_free_script(x);
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return -1;
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}
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xscr = xscr->next;
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m2->next = m->next;
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m->next = m2;
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m = m2;
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m->mode = 0;
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m->i1 = xscr->i1 + i1;
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m->chg1 = xscr->chg1;
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m->i2 = xscr->i2 + i2;
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m->chg2 = xscr->chg2;
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}
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xdl_free_env(&xe);
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xdl_free_script(x);
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}
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return 0;
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}
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/*
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* level == 0: mark all overlapping changes as conflict
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* level == 1: mark overlapping changes as conflict only if not identical
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* level == 2: analyze non-identical changes for minimal conflict set
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*
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* returns < 0 on error, == 0 for no conflicts, else number of conflicts
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*/
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static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
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xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
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int level, xpparam_t const *xpp, mmbuffer_t *result) {
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xdmerge_t *changes, *c;
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int i1, i2, chg1, chg2;
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c = changes = NULL;
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while (xscr1 && xscr2) {
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if (!changes)
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changes = c;
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if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
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i1 = xscr1->i2;
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i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
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chg1 = xscr1->chg2;
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chg2 = xscr1->chg1;
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if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
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xdl_cleanup_merge(changes);
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return -1;
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}
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xscr1 = xscr1->next;
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continue;
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}
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if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
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i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
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i2 = xscr2->i2;
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chg1 = xscr2->chg1;
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chg2 = xscr2->chg2;
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if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
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xdl_cleanup_merge(changes);
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return -1;
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}
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xscr2 = xscr2->next;
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continue;
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}
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if (level < 1 || xscr1->i1 != xscr2->i1 ||
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xscr1->chg1 != xscr2->chg1 ||
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xscr1->chg2 != xscr2->chg2 ||
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xdl_merge_cmp_lines(xe1, xscr1->i2,
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xe2, xscr2->i2,
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xscr1->chg2, xpp->flags)) {
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/* conflict */
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int off = xscr1->i1 - xscr2->i1;
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int ffo = off + xscr1->chg1 - xscr2->chg1;
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i1 = xscr1->i2;
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i2 = xscr2->i2;
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if (off > 0)
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i1 -= off;
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else
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i2 += off;
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chg1 = xscr1->i2 + xscr1->chg2 - i1;
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chg2 = xscr2->i2 + xscr2->chg2 - i2;
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if (ffo > 0)
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chg2 += ffo;
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else
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chg1 -= ffo;
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if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
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xdl_cleanup_merge(changes);
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return -1;
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}
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}
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i1 = xscr1->i1 + xscr1->chg1;
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i2 = xscr2->i1 + xscr2->chg1;
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if (i1 >= i2)
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xscr2 = xscr2->next;
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if (i2 >= i1)
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xscr1 = xscr1->next;
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}
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while (xscr1) {
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if (!changes)
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changes = c;
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i1 = xscr1->i2;
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i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
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chg1 = xscr1->chg2;
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chg2 = xscr1->chg1;
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if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
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xdl_cleanup_merge(changes);
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return -1;
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}
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xscr1 = xscr1->next;
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}
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while (xscr2) {
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if (!changes)
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changes = c;
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i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
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i2 = xscr2->i2;
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chg1 = xscr2->chg1;
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chg2 = xscr2->chg2;
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if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
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xdl_cleanup_merge(changes);
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return -1;
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}
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xscr2 = xscr2->next;
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}
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if (!changes)
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changes = c;
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/* refine conflicts */
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if (level > 1 && xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0) {
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xdl_cleanup_merge(changes);
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return -1;
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}
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/* output */
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if (result) {
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int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
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changes, NULL);
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result->ptr = xdl_malloc(size);
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if (!result->ptr) {
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xdl_cleanup_merge(changes);
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return -1;
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}
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result->size = size;
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xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
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result->ptr);
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}
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return xdl_cleanup_merge(changes);
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}
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int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
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mmfile_t *mf2, const char *name2,
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xpparam_t const *xpp, int level, mmbuffer_t *result) {
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xdchange_t *xscr1, *xscr2;
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xdfenv_t xe1, xe2;
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int status;
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result->ptr = NULL;
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result->size = 0;
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if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
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xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
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return -1;
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}
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if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
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xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
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xdl_build_script(&xe1, &xscr1) < 0) {
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xdl_free_env(&xe1);
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return -1;
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}
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if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
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xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
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xdl_build_script(&xe2, &xscr2) < 0) {
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xdl_free_env(&xe2);
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return -1;
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}
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status = 0;
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if (xscr1 || xscr2) {
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if (!xscr1) {
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result->ptr = xdl_malloc(mf2->size);
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memcpy(result->ptr, mf2->ptr, mf2->size);
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result->size = mf2->size;
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} else if (!xscr2) {
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result->ptr = xdl_malloc(mf1->size);
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memcpy(result->ptr, mf1->ptr, mf1->size);
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result->size = mf1->size;
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} else {
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status = xdl_do_merge(&xe1, xscr1, name1,
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&xe2, xscr2, name2,
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level, xpp, result);
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}
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xdl_free_script(xscr1);
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xdl_free_script(xscr2);
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}
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xdl_free_env(&xe1);
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xdl_free_env(&xe2);
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return status;
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}
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