From 857b933e04bc21ce02043c3107c148f8dcbb4a01 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date: Tue, 21 Nov 2006 23:24:34 +0100
Subject: [PATCH 01/10] xdiff: add xdl_merge()

This new function implements the functionality of RCS merge, but
in-memory. It returns < 0 on error, otherwise the number of conflicts.

Finding the conflicting lines can be a very expensive task. You can
control the eagerness of this algorithm:

- a level value of 0 means that all overlapping changes are treated
  as conflicts,
- a value of 1 means that if the overlapping changes are identical,
  it is not treated as a conflict.
- If you set level to 2, overlapping changes will be analyzed, so that
  almost identical changes will not result in huge conflicts. Rather,
  only the conflicting lines will be shown inside conflict markers.

With each increasing level, the algorithm gets slower, but more accurate.
Note that the code for level 2 depends on the simple definition of
mmfile_t specific to git, and therefore it will be harder to port that
to LibXDiff.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 Makefile       |   3 +-
 xdiff/xdiff.h  |   7 +
 xdiff/xdiffi.c |   3 +-
 xdiff/xdiffi.h |   1 +
 xdiff/xmerge.c | 433 +++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 444 insertions(+), 3 deletions(-)
 create mode 100644 xdiff/xmerge.c

diff --git a/Makefile b/Makefile
index de3e9f38ec..23bbb90683 100644
--- a/Makefile
+++ b/Makefile
@@ -723,7 +723,8 @@ $(DIFF_OBJS): diffcore.h
 $(LIB_FILE): $(LIB_OBJS)
 	rm -f $@ && $(AR) rcs $@ $(LIB_OBJS)
 
-XDIFF_OBJS=xdiff/xdiffi.o xdiff/xprepare.o xdiff/xutils.o xdiff/xemit.o
+XDIFF_OBJS=xdiff/xdiffi.o xdiff/xprepare.o xdiff/xutils.o xdiff/xemit.o \
+	xdiff/xmerge.o
 $(XDIFF_OBJS): xdiff/xinclude.h xdiff/xmacros.h xdiff/xdiff.h xdiff/xtypes.h \
 	xdiff/xutils.h xdiff/xprepare.h xdiff/xdiffi.h xdiff/xemit.h
 
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index c9f817818a..fa409d5234 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -49,6 +49,9 @@ extern "C" {
 #define XDL_BDOP_CPY 2
 #define XDL_BDOP_INSB 3
 
+#define XDL_MERGE_MINIMAL 0
+#define XDL_MERGE_EAGER 1
+#define XDL_MERGE_ZEALOUS 2
 
 typedef struct s_mmfile {
 	char *ptr;
@@ -90,6 +93,10 @@ long xdl_mmfile_size(mmfile_t *mmf);
 int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
 	     xdemitconf_t const *xecfg, xdemitcb_t *ecb);
 
+int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
+		mmfile_t *mf2, const char *name2,
+		xpparam_t const *xpp, int level, mmbuffer_t *result);
+
 #ifdef __cplusplus
 }
 #endif /* #ifdef __cplusplus */
diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c
index d76e76a0e6..9aeebc473b 100644
--- a/xdiff/xdiffi.c
+++ b/xdiff/xdiffi.c
@@ -45,7 +45,6 @@ static long xdl_split(unsigned long const *ha1, long off1, long lim1,
 		      long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl,
 		      xdalgoenv_t *xenv);
 static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2);
-static int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags);
 
 
 
@@ -397,7 +396,7 @@ static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1,
 }
 
 
-static int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
+int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
 	long ix, ixo, ixs, ixref, grpsiz, nrec = xdf->nrec;
 	char *rchg = xdf->rchg, *rchgo = xdfo->rchg;
 	xrecord_t **recs = xdf->recs;
diff --git a/xdiff/xdiffi.h b/xdiff/xdiffi.h
index d3b72716b5..472aeaecfa 100644
--- a/xdiff/xdiffi.h
+++ b/xdiff/xdiffi.h
@@ -50,6 +50,7 @@ int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1,
 		 long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv);
 int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
 		xdfenv_t *xe);
+int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags);
 int xdl_build_script(xdfenv_t *xe, xdchange_t **xscr);
 void xdl_free_script(xdchange_t *xscr);
 int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
new file mode 100644
index 0000000000..7b85aa5906
--- /dev/null
+++ b/xdiff/xmerge.c
@@ -0,0 +1,433 @@
+/*
+ *  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.
+	 */
+	int mode;
+	long i1, i2;
+	long chg1, chg2;
+} xdmerge_t;
+
+static int xdl_append_merge(xdmerge_t **merge, int mode,
+		long i1, long chg1, long i2, long chg2)
+{
+	xdmerge_t *m = *merge;
+	if (m && mode == m->mode &&
+			(i1 == m->i1 + m->chg1 || i2 == m->i2 + m->chg2)) {
+		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->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(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
+{
+	xrecord_t **recs = xe->xdf2.recs + i;
+	int size = 0;
+
+	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 (dest)
+				dest[size] = '\n';
+			size++;
+		}
+	}
+	return size;
+}
+
+static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
+		xdfenv_t *xe2, const char *name2, xdmerge_t *m, char *dest)
+{
+	const int marker_size = 7;
+	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
+	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
+	int conflict_marker_size = 3 * (marker_size + 1)
+		+ marker1_size + marker2_size;
+	int size, i1, j;
+
+	for (size = i1 = 0; m; m = m->next) {
+		if (m->mode == 0) {
+			size += xdl_recs_copy(xe1, i1, m->i1 - i1, 0,
+					dest ? dest + size : NULL);
+			if (dest) {
+				for (j = 0; j < marker_size; j++)
+					dest[size++] = '<';
+				if (marker1_size) {
+					dest[size] = ' ';
+					memcpy(dest + size + 1, name1,
+							marker1_size - 1);
+					size += marker1_size;
+				}
+				dest[size++] = '\n';
+			} else
+				size += conflict_marker_size;
+			size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
+					dest ? dest + size : NULL);
+			if (dest) {
+				for (j = 0; j < marker_size; j++)
+					dest[size++] = '=';
+				dest[size++] = '\n';
+			}
+			size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
+					dest ? dest + size : NULL);
+			if (dest) {
+				for (j = 0; j < marker_size; j++)
+					dest[size++] = '>';
+				if (marker2_size) {
+					dest[size] = ' ';
+					memcpy(dest + size + 1, name2,
+							marker2_size - 1);
+					size += marker2_size;
+				}
+				dest[size++] = '\n';
+			}
+		} else if (m->mode == 1)
+			size += xdl_recs_copy(xe1, i1, m->i1 + m->chg1 - i1, 0,
+					dest ? dest + size : NULL);
+		else if (m->mode == 2)
+			size += xdl_recs_copy(xe2, m->i2 - m->i1 + i1,
+					m->i1 + m->chg2 - i1, 0,
+					dest ? dest + size : NULL);
+		i1 = m->i1 + m->chg1;
+	}
+	size += xdl_recs_copy(xe1, i1, xe1->xdf2.nrec - i1, 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;
+
+		/*
+		 * 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]->ptr
+			+ xe1->xdf2.recs[m->i1 + m->chg1]->size - t1.ptr;
+		t2.ptr = (char *)xe2->xdf2.recs[m->i1]->ptr;
+		t2.size = xe2->xdf2.recs[m->i1 + m->chg1]->ptr
+			+ xe2->xdf2.recs[m->i1 + m->chg1]->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, it's a bug. */
+			xdl_free_env(&xe);
+			return -2;
+		}
+		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;
+}
+
+/*
+ * 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
+ *
+ * returns < 0 on error, == 0 for no conflicts, else number of conflicts
+ */
+static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
+		xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
+		int level, xpparam_t const *xpp, mmbuffer_t *result) {
+	xdmerge_t *changes, *c;
+	int i1, i2, chg1, chg2;
+
+	c = changes = NULL;
+
+	while (xscr1 && xscr2) {
+		if (!changes)
+			changes = c;
+		if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
+			i1 = xscr1->i2;
+			i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
+			chg1 = xscr1->chg2;
+			chg2 = xscr1->chg1;
+			if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
+				xdl_cleanup_merge(changes);
+				return -1;
+			}
+			xscr1 = xscr1->next;
+			continue;
+		}
+		if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
+			i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
+			i2 = xscr2->i2;
+			chg1 = xscr2->chg1;
+			chg2 = xscr2->chg2;
+			if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
+				xdl_cleanup_merge(changes);
+				return -1;
+			}
+			xscr2 = xscr2->next;
+			continue;
+		}
+		if (level < 1 || 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;
+
+			i1 = xscr1->i2;
+			i2 = xscr2->i2;
+			if (off > 0)
+				i1 -= off;
+			else
+				i2 += off;
+			chg1 = xscr1->i2 + xscr1->chg2 - i1;
+			chg2 = xscr2->i2 + xscr2->chg2 - i2;
+			if (ffo > 0)
+				chg2 += ffo;
+			else
+				chg1 -= ffo;
+			if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
+				xdl_cleanup_merge(changes);
+				return -1;
+			}
+		}
+
+		i1 = xscr1->i1 + xscr1->chg1;
+		i2 = xscr2->i1 + xscr2->chg1;
+
+		if (i1 > i2) {
+			xscr1->chg1 -= i1 - i2;
+			xscr1->i1 = i2;
+			xscr1->i2 += xscr1->chg2;
+			xscr1->chg2 = 0;
+			xscr1 = xscr1->next;
+		} else if (i2 > i1) {
+			xscr2->chg1 -= i2 - i1;
+			xscr2->i1 = i1;
+			xscr2->i2 += xscr2->chg2;
+			xscr2->chg2 = 0;
+			xscr2 = xscr2->next;
+		} else {
+			xscr1 = xscr1->next;
+			xscr2 = xscr2->next;
+		}
+	}
+	while (xscr1) {
+		if (!changes)
+			changes = c;
+		i1 = xscr1->i2;
+		i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
+		chg1 = xscr1->chg2;
+		chg2 = xscr1->chg1;
+		if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
+			xdl_cleanup_merge(changes);
+			return -1;
+		}
+		xscr1 = xscr1->next;
+	}
+	while (xscr2) {
+		if (!changes)
+			changes = c;
+		i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
+		i2 = xscr2->i2;
+		chg1 = xscr2->chg1;
+		chg2 = xscr2->chg2;
+		if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
+			xdl_cleanup_merge(changes);
+			return -1;
+		}
+		xscr2 = xscr2->next;
+	}
+	if (!changes)
+		changes = c;
+	/* refine conflicts */
+	if (level > 1 && xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0) {
+		xdl_cleanup_merge(changes);
+		return -1;
+	}
+	/* output */
+	if (result) {
+		int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
+			changes, NULL);
+		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, changes,
+				result->ptr);
+	}
+	return xdl_cleanup_merge(changes);
+}
+
+int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
+		mmfile_t *mf2, const char *name2,
+		xpparam_t const *xpp, int level, mmbuffer_t *result) {
+	xdchange_t *xscr1, *xscr2;
+	xdfenv_t xe1, xe2;
+
+	result->ptr = NULL;
+	result->size = 0;
+
+	if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
+			xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
+		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_env(&xe2);
+		return -1;
+	}
+	if (xscr1 || xscr2) {
+		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 if (xdl_do_merge(&xe1, xscr1, name1,
+					&xe2, xscr2, name2,
+					level, xpp, result) < 0) {
+			xdl_free_script(xscr1);
+			xdl_free_script(xscr2);
+			xdl_free_env(&xe1);
+			xdl_free_env(&xe2);
+			return -1;
+		}
+		xdl_free_script(xscr1);
+		xdl_free_script(xscr2);
+	}
+	xdl_free_env(&xe1);
+	xdl_free_env(&xe2);
+
+	return 0;
+}
+

From 53a7085a104936aef29400369aab15e0d1ccbb28 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <junkio@cox.net>
Date: Wed, 29 Nov 2006 12:06:49 -0800
Subject: [PATCH 02/10] xmerge: make return value from xdl_merge() more usable.

The callers would want to know if the resulting merge is clean;
do not discard that information away after calling xdl_do_merge().

Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 xdiff/xmerge.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 7b85aa5906..286f177b54 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -384,6 +384,7 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 		xpparam_t const *xpp, int level, mmbuffer_t *result) {
 	xdchange_t *xscr1, *xscr2;
 	xdfenv_t xe1, xe2;
+	int status;
 
 	result->ptr = NULL;
 	result->size = 0;
@@ -404,6 +405,7 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 		xdl_free_env(&xe2);
 		return -1;
 	}
+	status = 0;
 	if (xscr1 || xscr2) {
 		if (!xscr1) {
 			result->ptr = xdl_malloc(mf2->size);
@@ -413,14 +415,10 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 			result->ptr = xdl_malloc(mf1->size);
 			memcpy(result->ptr, mf1->ptr, mf1->size);
 			result->size = mf1->size;
-		} else if (xdl_do_merge(&xe1, xscr1, name1,
-					&xe2, xscr2, name2,
-					level, xpp, result) < 0) {
-			xdl_free_script(xscr1);
-			xdl_free_script(xscr2);
-			xdl_free_env(&xe1);
-			xdl_free_env(&xe2);
-			return -1;
+		} else {
+			status = xdl_do_merge(&xe1, xscr1, name1,
+					      &xe2, xscr2, name2,
+					      level, xpp, result);
 		}
 		xdl_free_script(xscr1);
 		xdl_free_script(xscr2);
@@ -428,6 +426,5 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 	xdl_free_env(&xe1);
 	xdl_free_env(&xe2);
 
-	return 0;
+	return status;
 }
-

From c2b4faea4522b28a7611ddab5eb6a5c221cc3ee5 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <junkio@cox.net>
Date: Wed, 29 Nov 2006 12:07:37 -0800
Subject: [PATCH 03/10] merge-recursive: use xdl_merge().

This seem to pass the existing tests already.

Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 merge-recursive.c | 86 +++++++++++++++++++----------------------------
 1 file changed, 35 insertions(+), 51 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index cd2cc77bf4..6e13b8ed5b 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -21,6 +21,7 @@
 #include "tag.h"
 #include "unpack-trees.h"
 #include "path-list.h"
+#include "xdiff-interface.h"
 
 /*
  * A virtual commit has
@@ -604,24 +605,15 @@ struct merge_file_info
 		 merge:1;
 };
 
-static char *git_unpack_file(const unsigned char *sha1, char *path)
+static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 {
-	void *buf;
-	char type[20];
 	unsigned long size;
-	int fd;
+	char type[20];
 
-	buf = read_sha1_file(sha1, type, &size);
-	if (!buf || strcmp(type, blob_type))
+	mm->ptr = read_sha1_file(sha1, type, &size);
+	if (!mm->ptr || strcmp(type, blob_type))
 		die("unable to read blob object %s", sha1_to_hex(sha1));
-
-	strcpy(path, ".merge_file_XXXXXX");
-	fd = mkstemp(path);
-	if (fd < 0)
-		die("unable to create temp-file");
-	flush_buffer(fd, buf, size);
-	close(fd);
-	return path;
+	mm->size = size;
 }
 
 static struct merge_file_info merge_file(struct diff_filespec *o,
@@ -652,49 +644,41 @@ static struct merge_file_info merge_file(struct diff_filespec *o,
 		else if (sha_eq(b->sha1, o->sha1))
 			hashcpy(result.sha, a->sha1);
 		else if (S_ISREG(a->mode)) {
-			int code = 1, fd;
-			struct stat st;
-			char orig[PATH_MAX];
-			char src1[PATH_MAX];
-			char src2[PATH_MAX];
-			const char *argv[] = {
-				"merge", "-L", NULL, "-L", NULL, "-L", NULL,
-				NULL, NULL, NULL,
-				NULL
-			};
-			char *la, *lb, *lo;
+			mmfile_t orig, src1, src2;
+			mmbuffer_t result_buf;
+			xpparam_t xpp;
+			char *name1, *name2;
+			int merge_status;
 
-			git_unpack_file(o->sha1, orig);
-			git_unpack_file(a->sha1, src1);
-			git_unpack_file(b->sha1, src2);
+			name1 = xstrdup(mkpath("%s/%s", branch1, a->path));
+			name2 = xstrdup(mkpath("%s/%s", branch2, b->path));
 
-			argv[2] = la = xstrdup(mkpath("%s/%s", branch1, a->path));
-			argv[6] = lb = xstrdup(mkpath("%s/%s", branch2, b->path));
-			argv[4] = lo = xstrdup(mkpath("orig/%s", o->path));
-			argv[7] = src1;
-			argv[8] = orig;
-			argv[9] = src2,
+			fill_mm(o->sha1, &orig);
+			fill_mm(a->sha1, &src1);
+			fill_mm(b->sha1, &src2);
 
-			code = run_command_v(10, argv);
+			memset(&xpp, 0, sizeof(xpp));
+			merge_status = xdl_merge(&orig,
+						 &src1, name1,
+						 &src2, name2,
+						 &xpp, XDL_MERGE_ZEALOUS,
+						 &result_buf);
+			free(name1);
+			free(name2);
+			free(orig.ptr);
+			free(src1.ptr);
+			free(src2.ptr);
 
-			free(la);
-			free(lb);
-			free(lo);
-			if (code && code < -256) {
-				die("Failed to execute 'merge'. merge(1) is used as the "
-				    "file-level merge tool. Is 'merge' in your path?");
-			}
-			fd = open(src1, O_RDONLY);
-			if (fd < 0 || fstat(fd, &st) < 0 ||
-					index_fd(result.sha, fd, &st, 1,
-						"blob"))
-				die("Unable to add %s to database", src1);
+			if ((merge_status < 0) || !result_buf.ptr)
+				die("Failed to execute internal merge");
 
-			unlink(orig);
-			unlink(src1);
-			unlink(src2);
+			if (write_sha1_file(result_buf.ptr, result_buf.size,
+					    blob_type, result.sha))
+				die("Unable to add %s to database",
+				    a->path);
 
-			result.clean = WEXITSTATUS(code) == 0;
+			free(result_buf.ptr);
+			result.clean = (merge_status == 0);
 		} else {
 			if (!(S_ISLNK(a->mode) || S_ISLNK(b->mode)))
 				die("cannot merge modes?");

From 875b8ce47650d712c8f464cfedb9147673fe3ff7 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date: Thu, 30 Nov 2006 00:24:32 +0100
Subject: [PATCH 04/10] xdl_merge(): fix an off-by-one bug

The line range is i1 .. (i1 + chg1 - 1), not i1 .. (i1 + chg1).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 xdiff/xmerge.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 286f177b54..3f5dc87fd2 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -194,11 +194,11 @@ static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 		 * 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]->ptr
-			+ xe1->xdf2.recs[m->i1 + m->chg1]->size - t1.ptr;
-		t2.ptr = (char *)xe2->xdf2.recs[m->i1]->ptr;
-		t2.size = xe2->xdf2.recs[m->i1 + m->chg1]->ptr
-			+ xe2->xdf2.recs[m->i1 + m->chg1]->size - t2.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 ||

From 710daa83fc76f79b8f2ee9a765d297187c2c1aeb Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date: Thu, 30 Nov 2006 00:25:11 +0100
Subject: [PATCH 05/10] xdl_merge(): fix thinko

If one side's block (of changed lines) ends later than the other
side's block, the former should be tested against the next block
of the other side, not vice versa.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 xdiff/xmerge.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 3f5dc87fd2..1fe7a1b060 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -318,13 +318,13 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 			xscr1->i1 = i2;
 			xscr1->i2 += xscr1->chg2;
 			xscr1->chg2 = 0;
-			xscr1 = xscr1->next;
+			xscr2 = xscr2->next;
 		} else if (i2 > i1) {
 			xscr2->chg1 -= i2 - i1;
 			xscr2->i1 = i1;
 			xscr2->i2 += xscr2->chg2;
 			xscr2->chg2 = 0;
-			xscr2 = xscr2->next;
+			xscr1 = xscr1->next;
 		} else {
 			xscr1 = xscr1->next;
 			xscr2 = xscr2->next;

From 98e6da8a360b77af2924e8056fd951013835699b Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date: Tue, 5 Dec 2006 22:15:35 +0100
Subject: [PATCH 06/10] xdl_merge(): fix and simplify conflict handling

Suppose you have changes in new1 to the original lines 10-20,
and changes in new2 to the original lines 15-25, then the
changes to 10-25 conflict. But it is possible that the next
changes in new1 still overlap with this change to new2.

So, in the next iteration we have to look at the same change
to new2 again.

The old code tried to be a bit too clever. The new code is
shorter and more to the point: do not fiddle with the ranges
at all.

Also, xdl_append_merge() tries harder to combine conflicts.
This is necessary, because with the above simplification,
some conflicts would not be recognized as conflicts otherwise:

In the above scenario, it is possible that there is no other
change to new1. Absent the combine logic, the change in new2
would be recorded _again_, but as a non-conflict.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
---
 xdiff/xmerge.c | 21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 1fe7a1b060..352207e516 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -38,8 +38,9 @@ static int xdl_append_merge(xdmerge_t **merge, int mode,
 		long i1, long chg1, long i2, long chg2)
 {
 	xdmerge_t *m = *merge;
-	if (m && mode == m->mode &&
-			(i1 == m->i1 + m->chg1 || i2 == m->i2 + m->chg2)) {
+	if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
+		if (mode != m->mode)
+			m->mode = 0;
 		m->chg1 = i1 + chg1 - m->i1;
 		m->chg2 = i2 + chg2 - m->i2;
 	} else {
@@ -313,22 +314,10 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 		i1 = xscr1->i1 + xscr1->chg1;
 		i2 = xscr2->i1 + xscr2->chg1;
 
-		if (i1 > i2) {
-			xscr1->chg1 -= i1 - i2;
-			xscr1->i1 = i2;
-			xscr1->i2 += xscr1->chg2;
-			xscr1->chg2 = 0;
+		if (i1 >= i2)
 			xscr2 = xscr2->next;
-		} else if (i2 > i1) {
-			xscr2->chg1 -= i2 - i1;
-			xscr2->i1 = i1;
-			xscr2->i2 += xscr2->chg2;
-			xscr2->chg2 = 0;
+		if (i2 >= i1)
 			xscr1 = xscr1->next;
-		} else {
-			xscr1 = xscr1->next;
-			xscr2 = xscr2->next;
-		}
 	}
 	while (xscr1) {
 		if (!changes)

From ba1f5f353775ddbf97bc0d543888783630693023 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date: Wed, 6 Dec 2006 16:26:06 +0100
Subject: [PATCH 07/10] Add builtin merge-file, a minimal replacement for RCS
 merge

merge-file has the same syntax as RCS merge, but supports only the
"-L" option.

For good measure, a test is added, which is quite minimal, though.

[jc: further fix for compliation errors included.]

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 Makefile              |   1 +
 builtin-merge-file.c  |  72 ++++++++++++++++++++++++++
 builtin.h             |   1 +
 git.c                 |   1 +
 t/t6023-merge-file.sh | 116 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 191 insertions(+)
 create mode 100644 builtin-merge-file.c
 create mode 100644 t/t6023-merge-file.sh

diff --git a/Makefile b/Makefile
index 23bbb90683..79cb91feec 100644
--- a/Makefile
+++ b/Makefile
@@ -275,6 +275,7 @@ BUILTIN_OBJS = \
 	builtin-ls-tree.o \
 	builtin-mailinfo.o \
 	builtin-mailsplit.o \
+	builtin-merge-file.o \
 	builtin-mv.o \
 	builtin-name-rev.o \
 	builtin-pack-objects.o \
diff --git a/builtin-merge-file.c b/builtin-merge-file.c
new file mode 100644
index 0000000000..41fb92edfb
--- /dev/null
+++ b/builtin-merge-file.c
@@ -0,0 +1,72 @@
+#include "cache.h"
+#include "xdiff/xdiff.h"
+
+static const char merge_file_usage[] =
+"git merge-file [-L name1 [-L orig [-L name2]]] file1 orig_file file2";
+
+static int read_file(mmfile_t *ptr, const char *filename)
+{
+	struct stat st;
+	FILE *f;
+
+	if (stat(filename, &st))
+		return error("Could not stat %s", filename);
+	if ((f = fopen(filename, "rb")) == NULL)
+		return error("Could not open %s", filename);
+	ptr->ptr = xmalloc(st.st_size);
+	if (fread(ptr->ptr, st.st_size, 1, f) != 1)
+		return error("Could not read %s", filename);
+	fclose(f);
+	ptr->size = st.st_size;
+	return 0;
+}
+
+int cmd_merge_file(int argc, char **argv, char **envp)
+{
+	char *names[3];
+	mmfile_t mmfs[3];
+	mmbuffer_t result = {NULL, 0};
+	xpparam_t xpp = {XDF_NEED_MINIMAL};
+	int ret = 0, i = 0;
+
+	while (argc > 4) {
+		if (!strcmp(argv[1], "-L")) {
+			names[i++] = argv[2];
+			argc -= 2;
+			argv += 2;
+			continue;
+		}
+		usage(merge_file_usage);
+	}
+
+	if (argc != 4)
+		usage(merge_file_usage);
+
+	for (; i < 3; i++)
+		names[i] = argv[i + 1];
+
+	for (i = 0; i < 3; i++)
+		if (read_file(mmfs + i, argv[i + 1]))
+			return -1;
+
+	ret = xdl_merge(mmfs + 1, mmfs + 0, names[0], mmfs + 2, names[2],
+			&xpp, XDL_MERGE_ZEALOUS, &result);
+
+	for (i = 0; i < 3; i++)
+		free(mmfs[i].ptr);
+
+	if (ret >= 0) {
+		char *filename = argv[1];
+		FILE *f = fopen(filename, "wb");
+
+		if (!f)
+			ret = error("Could not open %s for writing", filename);
+		else if (fwrite(result.ptr, result.size, 1, f) != 1)
+			ret = error("Could not write to %s", filename);
+		else if (fclose(f))
+			ret = error("Could not close %s", filename);
+		free(result.ptr);
+	}
+
+	return ret;
+}
diff --git a/builtin.h b/builtin.h
index b5116f30e4..08519e7c82 100644
--- a/builtin.h
+++ b/builtin.h
@@ -42,6 +42,7 @@ extern int cmd_ls_files(int argc, const char **argv, const char *prefix);
 extern int cmd_ls_tree(int argc, const char **argv, const char *prefix);
 extern int cmd_mailinfo(int argc, const char **argv, const char *prefix);
 extern int cmd_mailsplit(int argc, const char **argv, const char *prefix);
+extern int cmd_merge_file(int argc, const char **argv, const char *prefix);
 extern int cmd_mv(int argc, const char **argv, const char *prefix);
 extern int cmd_name_rev(int argc, const char **argv, const char *prefix);
 extern int cmd_pack_objects(int argc, const char **argv, const char *prefix);
diff --git a/git.c b/git.c
index 357330e02c..016ee8adb7 100644
--- a/git.c
+++ b/git.c
@@ -247,6 +247,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 		{ "ls-tree", cmd_ls_tree, RUN_SETUP },
 		{ "mailinfo", cmd_mailinfo },
 		{ "mailsplit", cmd_mailsplit },
+		{ "merge-file", cmd_merge_file },
 		{ "mv", cmd_mv, RUN_SETUP },
 		{ "name-rev", cmd_name_rev, RUN_SETUP },
 		{ "pack-objects", cmd_pack_objects, RUN_SETUP },
diff --git a/t/t6023-merge-file.sh b/t/t6023-merge-file.sh
new file mode 100644
index 0000000000..5d9b6f34b8
--- /dev/null
+++ b/t/t6023-merge-file.sh
@@ -0,0 +1,116 @@
+#!/bin/sh
+
+test_description='RCS merge replacement: merge-file'
+. ./test-lib.sh
+
+cat > orig.txt << EOF
+Dominus regit me,
+et nihil mihi deerit.
+In loco pascuae ibi me collocavit,
+super aquam refectionis educavit me;
+animam meam convertit,
+deduxit me super semitas jusitiae,
+propter nomen suum.
+EOF
+
+cat > new1.txt << EOF
+Dominus regit me,
+et nihil mihi deerit.
+In loco pascuae ibi me collocavit,
+super aquam refectionis educavit me;
+animam meam convertit,
+deduxit me super semitas jusitiae,
+propter nomen suum.
+Nam et si ambulavero in medio umbrae mortis,
+non timebo mala, quoniam tu mecum es:
+virga tua et baculus tuus ipsa me consolata sunt.
+EOF
+
+cat > new2.txt << EOF
+Dominus regit me, et nihil mihi deerit.
+In loco pascuae ibi me collocavit,
+super aquam refectionis educavit me;
+animam meam convertit,
+deduxit me super semitas jusitiae,
+propter nomen suum.
+EOF
+
+cat > new3.txt << EOF
+DOMINUS regit me,
+et nihil mihi deerit.
+In loco pascuae ibi me collocavit,
+super aquam refectionis educavit me;
+animam meam convertit,
+deduxit me super semitas jusitiae,
+propter nomen suum.
+EOF
+
+cat > new4.txt << EOF
+Dominus regit me, et nihil mihi deerit.
+In loco pascuae ibi me collocavit,
+super aquam refectionis educavit me;
+animam meam convertit,
+deduxit me super semitas jusitiae,
+EOF
+echo -n "propter nomen suum." >> new4.txt
+
+cp new1.txt test.txt
+test_expect_success "merge without conflict" \
+	"git-merge-file test.txt orig.txt new2.txt"
+
+cp new1.txt test2.txt
+test_expect_success "merge without conflict (missing LF at EOF)" \
+	"git-merge-file test2.txt orig.txt new2.txt"
+
+test_expect_success "merge result added missing LF" \
+	"diff -u test.txt test2.txt"
+
+cp test.txt backup.txt
+test_expect_failure "merge with conflicts" \
+	"git-merge-file test.txt orig.txt new3.txt"
+
+cat > expect.txt << EOF
+<<<<<<< test.txt
+Dominus regit me, et nihil mihi deerit.
+=======
+DOMINUS regit me,
+et nihil mihi deerit.
+>>>>>>> new3.txt
+In loco pascuae ibi me collocavit,
+super aquam refectionis educavit me;
+animam meam convertit,
+deduxit me super semitas jusitiae,
+propter nomen suum.
+Nam et si ambulavero in medio umbrae mortis,
+non timebo mala, quoniam tu mecum es:
+virga tua et baculus tuus ipsa me consolata sunt.
+EOF
+
+test_expect_success "expected conflict markers" "diff -u test.txt expect.txt"
+
+cp backup.txt test.txt
+test_expect_failure "merge with conflicts, using -L" \
+	"git-merge-file -L 1 -L 2 test.txt orig.txt new3.txt"
+
+cat > expect.txt << EOF
+<<<<<<< 1
+Dominus regit me, et nihil mihi deerit.
+=======
+DOMINUS regit me,
+et nihil mihi deerit.
+>>>>>>> new3.txt
+In loco pascuae ibi me collocavit,
+super aquam refectionis educavit me;
+animam meam convertit,
+deduxit me super semitas jusitiae,
+propter nomen suum.
+Nam et si ambulavero in medio umbrae mortis,
+non timebo mala, quoniam tu mecum es:
+virga tua et baculus tuus ipsa me consolata sunt.
+EOF
+
+test_expect_success "expected conflict markers, with -L" \
+	"diff -u test.txt expect.txt"
+
+test_done
+

From fbe0b24ca53111208b8ecd920cc112d0be13f93c Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date: Wed, 6 Dec 2006 16:45:42 +0100
Subject: [PATCH 08/10] merge-file: support -p and -q; fix compile warnings

Now merge-file also understands --stdout and --quiet options. While
at it, two compile warnings were fixed.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 builtin-merge-file.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/builtin-merge-file.c b/builtin-merge-file.c
index 41fb92edfb..6c4c3a3513 100644
--- a/builtin-merge-file.c
+++ b/builtin-merge-file.c
@@ -2,7 +2,7 @@
 #include "xdiff/xdiff.h"
 
 static const char merge_file_usage[] =
-"git merge-file [-L name1 [-L orig [-L name2]]] file1 orig_file file2";
+"git merge-file [-p | --stdout] [-q | --quiet] [-L name1 [-L orig [-L name2]]] file1 orig_file file2";
 
 static int read_file(mmfile_t *ptr, const char *filename)
 {
@@ -27,16 +27,23 @@ int cmd_merge_file(int argc, char **argv, char **envp)
 	mmfile_t mmfs[3];
 	mmbuffer_t result = {NULL, 0};
 	xpparam_t xpp = {XDF_NEED_MINIMAL};
-	int ret = 0, i = 0;
+	int ret = 0, i = 0, to_stdout = 0;
 
 	while (argc > 4) {
-		if (!strcmp(argv[1], "-L")) {
+		if (!strcmp(argv[1], "-L") && i < 3) {
 			names[i++] = argv[2];
-			argc -= 2;
-			argv += 2;
-			continue;
-		}
-		usage(merge_file_usage);
+			argc--;
+			argv++;
+		} else if (!strcmp(argv[1], "-p") ||
+				!strcmp(argv[1], "--stdout"))
+			to_stdout = 1;
+		else if (!strcmp(argv[1], "-q") ||
+				!strcmp(argv[1], "--quiet"))
+			freopen("/dev/null", "w", stderr);
+		else
+			usage(merge_file_usage);
+		argc--;
+		argv++;
 	}
 
 	if (argc != 4)
@@ -57,7 +64,7 @@ int cmd_merge_file(int argc, char **argv, char **envp)
 
 	if (ret >= 0) {
 		char *filename = argv[1];
-		FILE *f = fopen(filename, "wb");
+		FILE *f = to_stdout ? stdout : fopen(filename, "wb");
 
 		if (!f)
 			ret = error("Could not open %s for writing", filename);

From e2b7008752d85874919ea718d098fec01b4a9019 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date: Wed, 13 Dec 2006 00:01:41 +0100
Subject: [PATCH 09/10] Get rid of the dependency on RCS' merge program

Now that we have git-merge-file, an RCS merge lookalike, we no longer
need it. So long, merge, and thanks for all the fish!

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 .gitignore                        |  1 +
 Documentation/git-merge-index.txt |  4 +-
 INSTALL                           |  9 ----
 git-cvsserver.perl                |  2 +-
 git-rerere.perl                   |  2 +-
 git.spec.in                       |  2 +-
 merge-file.c                      | 73 +++++--------------------------
 t/t0000-basic.sh                  | 14 +-----
 8 files changed, 19 insertions(+), 88 deletions(-)

diff --git a/.gitignore b/.gitignore
index 7f2cd55088..d706dd92c6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -60,6 +60,7 @@ git-mailsplit
 git-merge
 git-merge-base
 git-merge-index
+git-merge-file
 git-merge-tree
 git-merge-octopus
 git-merge-one-file
diff --git a/Documentation/git-merge-index.txt b/Documentation/git-merge-index.txt
index 6cd0601082..0cf505ea84 100644
--- a/Documentation/git-merge-index.txt
+++ b/Documentation/git-merge-index.txt
@@ -40,8 +40,8 @@ If "git-merge-index" is called with multiple <file>s (or -a) then it
 processes them in turn only stopping if merge returns a non-zero exit
 code.
 
-Typically this is run with the a script calling the merge command from
-the RCS package.
+Typically this is run with the a script calling git's imitation of
+the merge command from the RCS package.
 
 A sample script called "git-merge-one-file" is included in the
 distribution.
diff --git a/INSTALL b/INSTALL
index 8f69039fb9..b5dd9f0abb 100644
--- a/INSTALL
+++ b/INSTALL
@@ -82,15 +82,6 @@ Issues of note:
 	  do that even if it wasn't for git.  There's no point in living
 	  in the dark ages any more. 
 
-	- "merge", the standard UNIX three-way merge program.  It usually
-	  comes with the "rcs" package on most Linux distributions, so if
-	  you have a developer install you probably have it already, but a
-	  "graphical user desktop" install might have left it out.
-
-	  You'll only need the merge program if you do development using
-	  git, and if you only use git to track other peoples work you'll
-	  never notice the lack of it. 
-
         - "wish", the Tcl/Tk windowing shell is used in gitk to show the
           history graphically
 
diff --git a/git-cvsserver.perl b/git-cvsserver.perl
index ca519b7e49..55ff83b1a3 100755
--- a/git-cvsserver.perl
+++ b/git-cvsserver.perl
@@ -945,7 +945,7 @@ sub req_update
 
             $log->debug("Temporary directory for merge is $dir");
 
-            my $return = system("merge", $file_local, $file_old, $file_new);
+            my $return = system("git merge-file", $file_local, $file_old, $file_new);
             $return >>= 8;
 
             if ( $return == 0 )
diff --git a/git-rerere.perl b/git-rerere.perl
index d3664ff491..2e8dbbd4ea 100755
--- a/git-rerere.perl
+++ b/git-rerere.perl
@@ -154,7 +154,7 @@ sub find_conflict {
 sub merge {
 	my ($name, $path) = @_;
 	record_preimage($path, "$rr_dir/$name/thisimage");
-	unless (system('merge', map { "$rr_dir/$name/${_}image" }
+	unless (system('git merge-file', map { "$rr_dir/$name/${_}image" }
 		       qw(this pre post))) {
 		my $in;
 		open $in, "<$rr_dir/$name/thisimage" or
diff --git a/git.spec.in b/git.spec.in
index f2374b7331..fb95e37594 100644
--- a/git.spec.in
+++ b/git.spec.in
@@ -24,7 +24,7 @@ This is a dummy package which brings in all subpackages.
 %package core
 Summary:	Core git tools
 Group:		Development/Tools
-Requires:	zlib >= 1.2, rsync, rcs, curl, less, openssh-clients, expat
+Requires:	zlib >= 1.2, rsync, curl, less, openssh-clients, expat
 %description core
 This is a stupid (but extremely fast) directory content manager.  It
 doesn't do a whole lot, but what it _does_ do is track directory
diff --git a/merge-file.c b/merge-file.c
index fc9b148993..69dc1ebbf7 100644
--- a/merge-file.c
+++ b/merge-file.c
@@ -3,52 +3,6 @@
 #include "xdiff-interface.h"
 #include "blob.h"
 
-static void rm_temp_file(const char *filename)
-{
-	unlink(filename);
-	free((void *)filename);
-}
-
-static const char *write_temp_file(mmfile_t *f)
-{
-	int fd;
-	const char *tmp = getenv("TMPDIR");
-	char *filename;
-
-	if (!tmp)
-		tmp = "/tmp";
-	filename = mkpath("%s/%s", tmp, "git-tmp-XXXXXX");
-	fd = mkstemp(filename);
-	if (fd < 0)
-		return NULL;
-	filename = xstrdup(filename);
-	if (f->size != xwrite(fd, f->ptr, f->size)) {
-		rm_temp_file(filename);
-		return NULL;
-	}
-	close(fd);
-	return filename;
-}
-
-static void *read_temp_file(const char *filename, unsigned long *size)
-{
-	struct stat st;
-	char *buf = NULL;
-	int fd = open(filename, O_RDONLY);
-	if (fd < 0)
-		return NULL;
-	if (!fstat(fd, &st)) {
-		*size = st.st_size;
-		buf = xmalloc(st.st_size);
-		if (st.st_size != xread(fd, buf, st.st_size)) {
-			free(buf);
-			buf = NULL;
-		}
-	}
-	close(fd);
-	return buf;
-}
-
 static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
 {
 	void *buf;
@@ -72,22 +26,19 @@ static void free_mmfile(mmfile_t *f)
 
 static void *three_way_filemerge(mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
 {
-	void *res;
-	const char *t1, *t2, *t3;
+	mmbuffer_t res;
+	xpparam_t xpp;
+	int merge_status;
 
-	t1 = write_temp_file(base);
-	t2 = write_temp_file(our);
-	t3 = write_temp_file(their);
-	res = NULL;
-	if (t1 && t2 && t3) {
-		int code = run_command("merge", t2, t1, t3, NULL);
-		if (!code || code == -1)
-			res = read_temp_file(t2, size);
-	}
-	rm_temp_file(t1);
-	rm_temp_file(t2);
-	rm_temp_file(t3);
-	return res;
+	memset(&xpp, 0, sizeof(xpp));
+	merge_status = xdl_merge(base, our, ".our", their, ".their",
+		&xpp, XDL_MERGE_ZEALOUS, &res);
+
+	if (merge_status < 0)
+		return NULL;
+
+	*size = res.size;
+	return res.ptr;
 }
 
 static int common_outf(void *priv_, mmbuffer_t *mb, int nbuf)
diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 81f3bedc90..3260d1d7a7 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -19,11 +19,7 @@ modification *should* take notice and update the test vectors here.
 '
 
 ################################################################
-# It appears that people are getting bitten by not installing
-# 'merge' (usually part of RCS package in binary distributions).
-# Check this and error out before running any tests.  Also catch
-# the bogosity of trying to run tests without building while we
-# are at it.
+# It appears that people try to run tests without building...
 
 ../git >/dev/null
 if test $? != 1
@@ -32,14 +28,6 @@ then
 	exit 1
 fi
 
-merge >/dev/null 2>/dev/null
-if test $? = 127
-then
-	echo >&2 'You do not seem to have "merge" installed.
-Please check INSTALL document.'
-	exit 1
-fi
-
 . ./test-lib.sh
 
 ################################################################

From f953831e030d3ece7346bdb5c4fde4fde43c925e Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date: Wed, 13 Dec 2006 04:05:39 +0100
Subject: [PATCH 10/10] merge-recursive: add/add really is modify/modify with
 an empty base

Unify the handling for cases C (add/add) and D (modify/modify).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 merge-recursive.c          | 44 +++++++++++++-------------------------
 t/t6024-recursive-merge.sh | 12 ++++++++++-
 2 files changed, 26 insertions(+), 30 deletions(-)
 mode change 100755 => 100644 t/t6024-recursive-merge.sh

diff --git a/merge-recursive.c b/merge-recursive.c
index 9d53bcd5d6..58f2cb4ed3 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -610,6 +610,12 @@ static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 	unsigned long size;
 	char type[20];
 
+	if (!hashcmp(sha1, null_sha1)) {
+		mm->ptr = xstrdup("");
+		mm->size = 0;
+		return;
+	}
+
 	mm->ptr = read_sha1_file(sha1, type, &size);
 	if (!mm->ptr || strcmp(type, blob_type))
 		die("unable to read blob object %s", sha1_to_hex(sha1));
@@ -1045,38 +1051,17 @@ static int process_entry(const char *path, struct stage_data *entry,
 			output("Adding %s", path);
 			update_file(1, sha, mode, path);
 		}
-	} else if (!o_sha && a_sha && b_sha) {
-		/* Case C: Added in both (check for same permissions). */
-		if (sha_eq(a_sha, b_sha)) {
-			if (a_mode != b_mode) {
-				clean_merge = 0;
-				output("CONFLICT: File %s added identically in both branches, "
-				       "but permissions conflict %06o->%06o",
-				       path, a_mode, b_mode);
-				output("CONFLICT: adding with permission: %06o", a_mode);
-				update_file(0, a_sha, a_mode, path);
-			} else {
-				/* This case is handled by git-read-tree */
-				assert(0 && "This case must be handled by git-read-tree");
-			}
-		} else {
-			const char *new_path1, *new_path2;
-			clean_merge = 0;
-			new_path1 = unique_path(path, branch1);
-			new_path2 = unique_path(path, branch2);
-			output("CONFLICT (add/add): File %s added non-identically "
-			       "in both branches. Adding as %s and %s instead.",
-			       path, new_path1, new_path2);
-			remove_file(0, path, 0);
-			update_file(0, a_sha, a_mode, new_path1);
-			update_file(0, b_sha, b_mode, new_path2);
-		}
-
-	} else if (o_sha && a_sha && b_sha) {
+	} else if (a_sha && b_sha) {
+		/* Case C: Added in both (check for same permissions) and */
 		/* case D: Modified in both, but differently. */
+		const char *reason = "content";
 		struct merge_file_info mfi;
 		struct diff_filespec o, a, b;
 
+		if (!o_sha) {
+			reason = "add/add";
+			o_sha = (unsigned char *)null_sha1;
+		}
 		output("Auto-merging %s", path);
 		o.path = a.path = b.path = (char *)path;
 		hashcpy(o.sha1, o_sha);
@@ -1093,7 +1078,8 @@ static int process_entry(const char *path, struct stage_data *entry,
 			update_file(1, mfi.sha, mfi.mode, path);
 		else {
 			clean_merge = 0;
-			output("CONFLICT (content): Merge conflict in %s", path);
+			output("CONFLICT (%s): Merge conflict in %s",
+					reason, path);
 
 			if (index_only)
 				update_file(0, mfi.sha, mfi.mode, path);
diff --git a/t/t6024-recursive-merge.sh b/t/t6024-recursive-merge.sh
old mode 100755
new mode 100644
index 9416c271eb..964010e764
--- a/t/t6024-recursive-merge.sh
+++ b/t/t6024-recursive-merge.sh
@@ -58,9 +58,19 @@ GIT_AUTHOR_DATE="2006-12-12 23:00:08" git commit -m F
 
 test_expect_failure "combined merge conflicts" "git merge -m final G"
 
+cat > expect << EOF
+<<<<<<< HEAD/a1
+F
+=======
+G
+>>>>>>> 26f86b677eb03d4d956dbe108b29cb77061c1e73/a1
+EOF
+
+test_expect_success "result contains a conflict" "diff -u expect a1"
+
 git ls-files --stage > out
 cat > expect << EOF
-100644 f70f10e4db19068f79bc43844b49f3eece45c4e8 1	a1
+100644 f16f906ab60483c100d1241dfc39868de9ec9fcb 1	a1
 100644 cf84443e49e1b366fac938711ddf4be2d4d1d9e9 2	a1
 100644 fd7923529855d0b274795ae3349c5e0438333979 3	a1
 EOF