From 73eb40eeaaebc5ebae283c06286b96b4aea00143 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 20 Jun 2008 00:17:27 -0700
Subject: git-merge-file --ours, --theirs

Sometimes people want their conflicting merges autoresolved by
favouring upstream changes.  The standard answer they are given is
to run "git diff --name-only | xargs git checkout MERGE_HEAD --" in
such a case.  This is to accept automerge results for the paths that
are fully resolved automatically, while taking their version of the
file in full for paths that have conflicts.

This is problematic on two counts.

One is that this is not exactly what these people want.  It discards
all changes they did on their branch for any paths that conflicted.
They usually want to salvage as much automerge result as possible in
a conflicted file, and want to take the upstream change only in the
conflicted part.

This patch teaches two new modes of operation to the lowest-lever
merge machinery, xdl_merge().  Instead of leaving the conflicted
lines from both sides enclosed in <<<, ===, and >>> markers, the
conflicts are resolved favouring our side or their side of changes.

A larger problem is that this tends to encourage a bad workflow by
allowing people to record such a mixed up half-merged result as a
full commit without auditing.  This commit does not tackle this
issue at all.  In git, we usually give long enough rope to users
with strange wishes as long as the risky features are not enabled by
default, and this is such a risky feature.

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-merge-file.txt b/Documentation/git-merge-file.txt
index 3035373..b9d2276 100644
--- a/Documentation/git-merge-file.txt
+++ b/Documentation/git-merge-file.txt
@@ -10,7 +10,8 @@ SYNOPSIS
 --------
 [verse]
 'git merge-file' [-L <current-name> [-L <base-name> [-L <other-name>]]]
-	[-p|--stdout] [-q|--quiet] <current-file> <base-file> <other-file>
+	[--ours|--theirs] [-p|--stdout] [-q|--quiet]
+	<current-file> <base-file> <other-file>
 
 
 DESCRIPTION
@@ -34,7 +35,9 @@ normally outputs a warning and brackets the conflict with lines containing
 	>>>>>>> B
 
 If there are conflicts, the user should edit the result and delete one of
-the alternatives.
+the alternatives.  When `--ours` or `--theirs` option is in effect, however,
+these conflicts are resolved favouring lines from `<current-file>` or
+lines from `<other-file>` respectively.
 
 The exit value of this program is negative on error, and the number of
 conflicts otherwise. If the merge was clean, the exit value is 0.
@@ -62,6 +65,11 @@ OPTIONS
 -q::
 	Quiet; do not warn about conflicts.
 
+--ours::
+--theirs::
+	Instead of leaving conflicts in the file, resolve conflicts
+	favouring our (or their) side of the lines.
+
 
 EXAMPLES
 --------
diff --git a/builtin-merge-file.c b/builtin-merge-file.c
index afd2ea7..1efc4e0 100644
--- a/builtin-merge-file.c
+++ b/builtin-merge-file.c
@@ -27,13 +27,18 @@ int cmd_merge_file(int argc, const char **argv, const char *prefix)
 	mmbuffer_t result = {NULL, 0};
 	xpparam_t xpp = {XDF_NEED_MINIMAL};
 	int ret = 0, i = 0, to_stdout = 0;
-	int merge_level = XDL_MERGE_ZEALOUS_ALNUM;
-	int merge_style = 0, quiet = 0;
+	int level = XDL_MERGE_ZEALOUS_ALNUM;
+	int style = 0, quiet = 0;
+	int favor = 0;
 	int nongit;
 
 	struct option options[] = {
 		OPT_BOOLEAN('p', "stdout", &to_stdout, "send results to standard output"),
-		OPT_SET_INT(0, "diff3", &merge_style, "use a diff3 based merge", XDL_MERGE_DIFF3),
+		OPT_SET_INT(0, "diff3", &style, "use a diff3 based merge", XDL_MERGE_DIFF3),
+		OPT_SET_INT(0, "ours", &favor, "for conflicts, use our version",
+			    XDL_MERGE_FAVOR_OURS),
+		OPT_SET_INT(0, "theirs", &favor, "for conflicts, use their version",
+			    XDL_MERGE_FAVOR_THEIRS),
 		OPT__QUIET(&quiet),
 		OPT_CALLBACK('L', NULL, names, "name",
 			     "set labels for file1/orig_file/file2", &label_cb),
@@ -45,7 +50,7 @@ int cmd_merge_file(int argc, const char **argv, const char *prefix)
 		/* Read the configuration file */
 		git_config(git_xmerge_config, NULL);
 		if (0 <= git_xmerge_style)
-			merge_style = git_xmerge_style;
+			style = git_xmerge_style;
 	}
 
 	argc = parse_options(argc, argv, prefix, options, merge_file_usage, 0);
@@ -68,7 +73,7 @@ int cmd_merge_file(int argc, const char **argv, const char *prefix)
 	}
 
 	ret = xdl_merge(mmfs + 1, mmfs + 0, names[0], mmfs + 2, names[2],
-			&xpp, merge_level | merge_style, &result);
+			&xpp, XDL_MERGE_FLAGS(level, style, favor), &result);
 
 	for (i = 0; i < 3; i++)
 		free(mmfs[i].ptr);
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index 4da052a..8a0efed 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -58,6 +58,12 @@ extern "C" {
 #define XDL_MERGE_ZEALOUS_ALNUM 3
 #define XDL_MERGE_LEVEL_MASK 0x0f
 
+/* merge favor modes */
+#define XDL_MERGE_FAVOR_OURS 1
+#define XDL_MERGE_FAVOR_THEIRS 2
+#define XDL_MERGE_FAVOR(flags) (((flags)>>4) & 3)
+#define XDL_MERGE_FLAGS(level, style, favor) ((level)|(style)|((favor)<<4))
+
 /* merge output styles */
 #define XDL_MERGE_DIFF3 0x8000
 #define XDL_MERGE_STYLE_MASK 0x8000
@@ -110,7 +116,7 @@ int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
 
 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);
+		xpparam_t const *xpp, int flags, mmbuffer_t *result);
 
 #ifdef __cplusplus
 }
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 1cb65a9..b2ddc75 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -214,11 +214,15 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 
 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 				 xdfenv_t *xe2, const char *name2,
+				 int favor,
 				 xdmerge_t *m, char *dest, int style)
 {
 	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,
 						  size, i, style, m, dest);
@@ -391,6 +395,7 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 	int i0, i1, i2, chg0, chg1, chg2;
 	int level = flags & XDL_MERGE_LEVEL_MASK;
 	int style = flags & XDL_MERGE_STYLE_MASK;
+	int favor = XDL_MERGE_FAVOR(flags);
 
 	if (style == XDL_MERGE_DIFF3) {
 		/*
@@ -523,14 +528,14 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 	/* output */
 	if (result) {
 		int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
-			changes, NULL, style);
+			favor, changes, NULL, style);
 		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,
+		xdl_fill_merge_buffer(xe1, name1, xe2, name2, favor, changes,
 				      result->ptr, style);
 	}
 	return xdl_cleanup_merge(changes);
-- 
cgit v0.10.2-6-g49f6


From 8cc5b29065e19267cbc08b39c34674b02c2e3d59 Mon Sep 17 00:00:00 2001
From: Avery Pennarun <apenwarr@gmail.com>
Date: Wed, 25 Nov 2009 21:23:55 -0500
Subject: git merge -X<option>

Teach "-X <option>" command line argument to "git merge" that is passed to
strategy implementations.  "ours" and "theirs" autoresolution introduced
by the previous commit can be asked to the recursive strategy.

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-merge-recursive.c b/builtin-merge-recursive.c
index 710674c..1a160d8 100644
--- a/builtin-merge-recursive.c
+++ b/builtin-merge-recursive.c
@@ -26,18 +26,29 @@ int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
 
 	init_merge_options(&o);
 	if (argv[0]) {
-		int namelen = strlen(argv[0]);
-		if (8 < namelen &&
-		    !strcmp(argv[0] + namelen - 8, "-subtree"))
-			o.subtree_merge = 1;
+		if (!suffixcmp(argv[0], "-subtree"))
+			o.recursive_variant = MERGE_RECURSIVE_SUBTREE;
 	}
 
 	if (argc < 4)
 		usagef("%s <base>... -- <head> <remote> ...", argv[0]);
 
 	for (i = 1; i < argc; ++i) {
-		if (!strcmp(argv[i], "--"))
-			break;
+		const char *arg = argv[i];
+
+		if (!prefixcmp(arg, "--")) {
+			if (!arg[2])
+				break;
+			if (!strcmp(arg+2, "ours"))
+				o.recursive_variant = MERGE_RECURSIVE_OURS;
+			else if (!strcmp(arg+2, "theirs"))
+				o.recursive_variant = MERGE_RECURSIVE_THEIRS;
+			else if (!strcmp(arg+2, "subtree"))
+				o.recursive_variant = MERGE_RECURSIVE_SUBTREE;
+			else
+				die("Unknown option %s", arg);
+			continue;
+		}
 		if (bases_count < ARRAY_SIZE(bases)-1) {
 			unsigned char *sha = xmalloc(20);
 			if (get_sha1(argv[i], sha))
diff --git a/builtin-merge.c b/builtin-merge.c
index 855cf65..42f19e1 100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -50,6 +50,8 @@ static struct commit_list *remoteheads;
 static unsigned char head[20], stash[20];
 static struct strategy **use_strategies;
 static size_t use_strategies_nr, use_strategies_alloc;
+static const char **xopts;
+static size_t xopts_nr, xopts_alloc;
 static const char *branch;
 static int verbosity;
 
@@ -146,6 +148,17 @@ static int option_parse_strategy(const struct option *opt,
 	return 0;
 }
 
+static int option_parse_x(const struct option *opt,
+			  const char *arg, int unset)
+{
+	if (unset)
+		return 0;
+
+	ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
+	xopts[xopts_nr++] = xstrdup(arg);
+	return 0;
+}
+
 static int option_parse_n(const struct option *opt,
 			  const char *arg, int unset)
 {
@@ -172,6 +185,8 @@ static struct option builtin_merge_options[] = {
 		"abort if fast-forward is not possible"),
 	OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
 		"merge strategy to use", option_parse_strategy),
+	OPT_CALLBACK('X', "strategy-option", &xopts, "option=value",
+		"option for selected merge strategy", option_parse_x),
 	OPT_CALLBACK('m', "message", &merge_msg, "message",
 		"message to be used for the merge commit (if any)",
 		option_parse_message),
@@ -534,7 +549,7 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 			      const char *head_arg)
 {
 	const char **args;
-	int i = 0, ret;
+	int i = 0, x = 0, ret;
 	struct commit_list *j;
 	struct strbuf buf = STRBUF_INIT;
 	int index_fd;
@@ -563,7 +578,18 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 
 		init_merge_options(&o);
 		if (!strcmp(strategy, "subtree"))
-			o.subtree_merge = 1;
+			o.recursive_variant = MERGE_RECURSIVE_SUBTREE;
+
+		for (x = 0; x < xopts_nr; x++) {
+			if (!strcmp(xopts[x], "ours"))
+				o.recursive_variant = MERGE_RECURSIVE_OURS;
+			else if (!strcmp(xopts[x], "theirs"))
+				o.recursive_variant = MERGE_RECURSIVE_THEIRS;
+			else if (!strcmp(xopts[x], "subtree"))
+				o.recursive_variant = MERGE_RECURSIVE_SUBTREE;
+			else
+				die("Unknown option for merge-recursive: -X%s", xopts[x]);
+		}
 
 		o.branch1 = head_arg;
 		o.branch2 = remoteheads->item->util;
@@ -581,10 +607,16 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 		rollback_lock_file(lock);
 		return clean ? 0 : 1;
 	} else {
-		args = xmalloc((4 + commit_list_count(common) +
+		args = xmalloc((4 + xopts_nr + commit_list_count(common) +
 					commit_list_count(remoteheads)) * sizeof(char *));
 		strbuf_addf(&buf, "merge-%s", strategy);
 		args[i++] = buf.buf;
+		for (x = 0; x < xopts_nr; x++) {
+			char *s = xmalloc(strlen(xopts[x])+2+1);
+			strcpy(s, "--");
+			strcpy(s+2, xopts[x]);
+			args[i++] = s;
+		}
 		for (j = common; j; j = j->next)
 			args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
 		args[i++] = "--";
@@ -595,6 +627,8 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 		ret = run_command_v_opt(args, RUN_GIT_CMD);
 		strbuf_release(&buf);
 		i = 1;
+		for (x = 0; x < xopts_nr; x++)
+			free((void *)args[i++]);
 		for (j = common; j; j = j->next)
 			free((void *)args[i++]);
 		i += 2;
diff --git a/contrib/examples/git-merge.sh b/contrib/examples/git-merge.sh
index 500635f..8f617fc 100755
--- a/contrib/examples/git-merge.sh
+++ b/contrib/examples/git-merge.sh
@@ -31,10 +31,11 @@ LF='
 '
 
 all_strategies='recur recursive octopus resolve stupid ours subtree'
+all_strategies="$all_strategies recursive-ours recursive-theirs"
 default_twohead_strategies='recursive'
 default_octopus_strategies='octopus'
 no_fast_forward_strategies='subtree ours'
-no_trivial_strategies='recursive recur subtree ours'
+no_trivial_strategies='recursive recur subtree ours recursive-ours recursive-theirs'
 use_strategies=
 
 allow_fast_forward=t
diff --git a/git-compat-util.h b/git-compat-util.h
index 5c59687..f64cc45 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -198,6 +198,7 @@ extern void warning(const char *err, ...) __attribute__((format (printf, 1, 2)))
 extern void set_die_routine(NORETURN_PTR void (*routine)(const char *err, va_list params));
 
 extern int prefixcmp(const char *str, const char *prefix);
+extern int suffixcmp(const char *str, const char *suffix);
 extern time_t tm_to_time_t(const struct tm *tm);
 
 static inline const char *skip_prefix(const char *str, const char *prefix)
diff --git a/git.c b/git.c
index 11544cd..4735f11 100644
--- a/git.c
+++ b/git.c
@@ -332,6 +332,8 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "merge-file", cmd_merge_file },
 		{ "merge-ours", cmd_merge_ours, RUN_SETUP },
 		{ "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
+		{ "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
+		{ "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 		{ "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 		{ "mktree", cmd_mktree, RUN_SETUP },
 		{ "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
diff --git a/ll-merge.c b/ll-merge.c
index 2d6b6d6..45f7e01 100644
--- a/ll-merge.c
+++ b/ll-merge.c
@@ -18,7 +18,7 @@ typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
 			   mmfile_t *orig,
 			   mmfile_t *src1, const char *name1,
 			   mmfile_t *src2, const char *name2,
-			   int virtual_ancestor);
+			   int flag);
 
 struct ll_merge_driver {
 	const char *name;
@@ -38,14 +38,14 @@ static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 			   mmfile_t *orig,
 			   mmfile_t *src1, const char *name1,
 			   mmfile_t *src2, const char *name2,
-			   int virtual_ancestor)
+			   int flag)
 {
 	/*
 	 * The tentative merge result is "ours" for the final round,
 	 * or common ancestor for an internal merge.  Still return
 	 * "conflicted merge" status.
 	 */
-	mmfile_t *stolen = virtual_ancestor ? orig : src1;
+	mmfile_t *stolen = (flag & 01) ? orig : src1;
 
 	result->ptr = stolen->ptr;
 	result->size = stolen->size;
@@ -59,10 +59,11 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 			mmfile_t *orig,
 			mmfile_t *src1, const char *name1,
 			mmfile_t *src2, const char *name2,
-			int virtual_ancestor)
+			int flag)
 {
 	xpparam_t xpp;
 	int style = 0;
+	int favor = (flag >> 1) & 03;
 
 	if (buffer_is_binary(orig->ptr, orig->size) ||
 	    buffer_is_binary(src1->ptr, src1->size) ||
@@ -72,8 +73,7 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 		return ll_binary_merge(drv_unused, result,
 				       path,
 				       orig, src1, name1,
-				       src2, name2,
-				       virtual_ancestor);
+				       src2, name2, flag);
 	}
 
 	memset(&xpp, 0, sizeof(xpp));
@@ -82,7 +82,7 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 	return xdl_merge(orig,
 			 src1, name1,
 			 src2, name2,
-			 &xpp, XDL_MERGE_ZEALOUS | style,
+			 &xpp, XDL_MERGE_FLAGS(XDL_MERGE_ZEALOUS, style, favor),
 			 result);
 }
 
@@ -92,7 +92,7 @@ static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 			  mmfile_t *orig,
 			  mmfile_t *src1, const char *name1,
 			  mmfile_t *src2, const char *name2,
-			  int virtual_ancestor)
+			  int flag)
 {
 	char *src, *dst;
 	long size;
@@ -104,7 +104,7 @@ static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 	git_xmerge_style = 0;
 	status = ll_xdl_merge(drv_unused, result, path_unused,
 			      orig, src1, NULL, src2, NULL,
-			      virtual_ancestor);
+			      flag);
 	git_xmerge_style = saved_style;
 	if (status <= 0)
 		return status;
@@ -165,7 +165,7 @@ static int ll_ext_merge(const struct ll_merge_driver *fn,
 			mmfile_t *orig,
 			mmfile_t *src1, const char *name1,
 			mmfile_t *src2, const char *name2,
-			int virtual_ancestor)
+			int flag)
 {
 	char temp[3][50];
 	struct strbuf cmd = STRBUF_INIT;
@@ -356,10 +356,11 @@ int ll_merge(mmbuffer_t *result_buf,
 	     mmfile_t *ancestor,
 	     mmfile_t *ours, const char *our_label,
 	     mmfile_t *theirs, const char *their_label,
-	     int virtual_ancestor)
+	     int flag)
 {
 	const char *ll_driver_name;
 	const struct ll_merge_driver *driver;
+	int virtual_ancestor = flag & 01;
 
 	ll_driver_name = git_path_check_merge(path);
 	driver = find_ll_merge_driver(ll_driver_name);
@@ -369,5 +370,5 @@ int ll_merge(mmbuffer_t *result_buf,
 	return driver->fn(driver, result_buf, path,
 			  ancestor,
 			  ours, our_label,
-			  theirs, their_label, virtual_ancestor);
+			  theirs, their_label, flag);
 }
diff --git a/ll-merge.h b/ll-merge.h
index 5388422..aaed46d 100644
--- a/ll-merge.h
+++ b/ll-merge.h
@@ -10,6 +10,6 @@ int ll_merge(mmbuffer_t *result_buf,
 	     mmfile_t *ancestor,
 	     mmfile_t *ours, const char *our_label,
 	     mmfile_t *theirs, const char *their_label,
-	     int virtual_ancestor);
+	     int flag);
 
 #endif
diff --git a/merge-recursive.c b/merge-recursive.c
index a91208f..82f24ac 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -642,6 +642,23 @@ static int merge_3way(struct merge_options *o,
 	mmfile_t orig, src1, src2;
 	char *name1, *name2;
 	int merge_status;
+	int favor;
+
+	if (o->call_depth)
+		favor = 0;
+	else {
+		switch (o->recursive_variant) {
+		case MERGE_RECURSIVE_OURS:
+			favor = XDL_MERGE_FAVOR_OURS;
+			break;
+		case MERGE_RECURSIVE_THEIRS:
+			favor = XDL_MERGE_FAVOR_THEIRS;
+			break;
+		default:
+			favor = 0;
+			break;
+		}
+	}
 
 	if (strcmp(a->path, b->path)) {
 		name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
@@ -657,7 +674,7 @@ static int merge_3way(struct merge_options *o,
 
 	merge_status = ll_merge(result_buf, a->path, &orig,
 				&src1, name1, &src2, name2,
-				o->call_depth);
+				(!!o->call_depth) | (favor << 1));
 
 	free(name1);
 	free(name2);
@@ -1196,7 +1213,7 @@ int merge_trees(struct merge_options *o,
 {
 	int code, clean;
 
-	if (o->subtree_merge) {
+	if (o->recursive_variant == MERGE_RECURSIVE_SUBTREE) {
 		merge = shift_tree_object(head, merge);
 		common = shift_tree_object(head, common);
 	}
diff --git a/merge-recursive.h b/merge-recursive.h
index fd138ca..39de100 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -6,7 +6,11 @@
 struct merge_options {
 	const char *branch1;
 	const char *branch2;
-	unsigned subtree_merge : 1;
+	enum {
+		MERGE_RECURSIVE_SUBTREE = 1,
+		MERGE_RECURSIVE_OURS,
+		MERGE_RECURSIVE_THEIRS,
+	} recursive_variant;
 	unsigned buffer_output : 1;
 	int verbosity;
 	int diff_rename_limit;
diff --git a/strbuf.c b/strbuf.c
index a6153dc..d71a623 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -10,6 +10,15 @@ int prefixcmp(const char *str, const char *prefix)
 			return (unsigned char)*prefix - (unsigned char)*str;
 }
 
+int suffixcmp(const char *str, const char *suffix)
+{
+	int len = strlen(str), suflen = strlen(suffix);
+	if (len < suflen)
+		return -1;
+	else
+		return strcmp(str + len - suflen, suffix);
+}
+
 /*
  * Used as the default ->buf value, so that people can always assume
  * buf is non NULL and ->buf is NUL terminated even for a freshly
diff --git a/t/t6037-merge-ours-theirs.sh b/t/t6037-merge-ours-theirs.sh
new file mode 100755
index 0000000..08c9f79
--- /dev/null
+++ b/t/t6037-merge-ours-theirs.sh
@@ -0,0 +1,56 @@
+#!/bin/sh
+
+test_description='Merge-recursive ours and theirs variants'
+. ./test-lib.sh
+
+test_expect_success setup '
+	for i in 1 2 3 4 5 6 7 8 9
+	do
+		echo "$i"
+	done >file &&
+	git add file &&
+	cp file elif &&
+	git commit -m initial &&
+
+	sed -e "s/1/one/" -e "s/9/nine/" >file <elif &&
+	git commit -a -m ours &&
+
+	git checkout -b side HEAD^ &&
+
+	sed -e "s/9/nueve/" >file <elif &&
+	git commit -a -m theirs &&
+
+	git checkout master^0
+'
+
+test_expect_success 'plain recursive - should conflict' '
+	git reset --hard master &&
+	test_must_fail git merge -s recursive side &&
+	grep nine file &&
+	grep nueve file &&
+	! grep 9 file &&
+	grep one file &&
+	! grep 1 file
+'
+
+test_expect_success 'recursive favouring theirs' '
+	git reset --hard master &&
+	git merge -s recursive -Xtheirs side &&
+	! grep nine file &&
+	grep nueve file &&
+	! grep 9 file &&
+	grep one file &&
+	! grep 1 file
+'
+
+test_expect_success 'recursive favouring ours' '
+	git reset --hard master &&
+	git merge -s recursive -X ours side &&
+	grep nine file &&
+	! grep nueve file &&
+	! grep 9 file &&
+	grep one file &&
+	! grep 1 file
+'
+
+test_done
-- 
cgit v0.10.2-6-g49f6


From ee2c79552acceaa59a78518c6c084bd515606374 Mon Sep 17 00:00:00 2001
From: Avery Pennarun <apenwarr@gmail.com>
Date: Wed, 25 Nov 2009 21:23:57 -0500
Subject: Teach git-pull to pass -X<option> to git-merge

This needs the usual sq then eval trick to allow IFS characters
in the option.

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-pull.sh b/git-pull.sh
index bfeb4a0..6d961b6 100755
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -18,6 +18,7 @@ test -z "$(git ls-files -u)" ||
 
 strategy_args= diffstat= no_commit= squash= no_ff= ff_only=
 log_arg= verbosity=
+merge_args=
 curr_branch=$(git symbolic-ref -q HEAD)
 curr_branch_short=$(echo "$curr_branch" | sed "s|refs/heads/||")
 rebase=$(git config --bool branch.$curr_branch_short.rebase)
@@ -62,6 +63,18 @@ do
 		esac
 		strategy_args="${strategy_args}-s $strategy "
 		;;
+	-X*)
+		case "$#,$1" in
+		1,-X)
+			usage ;;
+		*,-X)
+			xx="-X $2"
+			shift ;;
+		*,*)
+			xx="$1" ;;
+		esac
+		merge_args="$merge_args$xx "
+		;;
 	-r|--r|--re|--reb|--reba|--rebas|--rebase)
 		rebase=true
 		;;
@@ -216,7 +229,7 @@ fi
 
 merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit
 test true = "$rebase" &&
-	exec git-rebase $diffstat $strategy_args --onto $merge_head \
+	exec git-rebase $diffstat $strategy_args $merge_args --onto $merge_head \
 	${oldremoteref:-$merge_head}
-exec git-merge $diffstat $no_commit $squash $no_ff $ff_only $log_arg $strategy_args \
+exec git-merge $diffstat $no_commit $squash $no_ff $ff_only $log_arg $strategy_args $merge_args \
 	"$merge_name" HEAD $merge_head $verbosity
diff --git a/t/t6037-merge-ours-theirs.sh b/t/t6037-merge-ours-theirs.sh
index 08c9f79..8ab3d61 100755
--- a/t/t6037-merge-ours-theirs.sh
+++ b/t/t6037-merge-ours-theirs.sh
@@ -53,4 +53,12 @@ test_expect_success 'recursive favouring ours' '
 	! grep 1 file
 '
 
+test_expect_success 'pull with -X' '
+	git reset --hard master && git pull -s recursive -Xours . side &&
+	git reset --hard master && git pull -s recursive -X ours . side &&
+	git reset --hard master && git pull -s recursive -Xtheirs . side &&
+	git reset --hard master && git pull -s recursive -X theirs . side &&
+	git reset --hard master && ! git pull -s recursive -X bork . side
+'
+
 test_done
-- 
cgit v0.10.2-6-g49f6


From 14e5d40ca4f4f118fe03cbe5302309170b46096d Mon Sep 17 00:00:00 2001
From: Junio C Hamano <gitster@pobox.com>
Date: Sun, 17 Jan 2010 22:31:38 -0800
Subject: pull: Fix parsing of -X<option>

As -X parameter can contain arbitrary $IFS characters, we need to
properly quote it from the shell while forming the command line.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-pull.sh b/git-pull.sh
index 6d961b6..fc3536b 100755
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -68,10 +68,10 @@ do
 		1,-X)
 			usage ;;
 		*,-X)
-			xx="-X $2"
+			xx="-X $(git rev-parse --sq-quote "$2")"
 			shift ;;
 		*,*)
-			xx="$1" ;;
+			xx=$(git rev-parse --sq-quote "$1") ;;
 		esac
 		merge_args="$merge_args$xx "
 		;;
@@ -228,8 +228,15 @@ then
 fi
 
 merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit
-test true = "$rebase" &&
-	exec git-rebase $diffstat $strategy_args $merge_args --onto $merge_head \
-	${oldremoteref:-$merge_head}
-exec git-merge $diffstat $no_commit $squash $no_ff $ff_only $log_arg $strategy_args $merge_args \
-	"$merge_name" HEAD $merge_head $verbosity
+case "$rebase" in
+true)
+	eval="git-rebase $diffstat $strategy_args $merge_args"
+	eval="$eval --onto $merge_head ${oldremoteref:-$merge_head}"
+	;;
+*)
+	eval="git-merge $diffstat $no_commit $squash $no_ff $ff_only"
+	eval="$eval  $log_arg $strategy_args $merge_args"
+	eval="$eval \"$merge_name\" HEAD $merge_head $verbosity"
+	;;
+esac
+eval "exec $eval"
-- 
cgit v0.10.2-6-g49f6


From 85e51b783c3a92b42275442147e7a27e17d42276 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 30 Jun 2008 22:18:57 -0700
Subject: Make "subtree" part more orthogonal to the rest of merge-recursive.

This makes "subtree" more orthogonal to the rest of recursive merge, so
that you can use subtree and ours/theirs features at the same time.  For
example, you can now say:

	git merge -s subtree -Xtheirs other

to merge with "other" branch while shifting it up or down to match the
shape of the tree of the current branch, and resolving conflicts favoring
the changes "other" branch made over changes made in the current branch.

It also allows the prefix used to shift the trees to be specified using
the "-Xsubtree=$prefix" option.  Giving an empty prefix tells the command
to figure out how much to shift trees automatically as we have always
done.  "merge -s subtree" is the same as "merge -s recursive -Xsubtree="
(or "merge -s recursive -Xsubtree").

Based on an old patch done back in the days when git-merge was a script;
Avery ported the script part to builtin-merge.c.  Bugs in shift_tree()
is mine.

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-merge-recursive.c b/builtin-merge-recursive.c
index 1a160d8..d8875d5 100644
--- a/builtin-merge-recursive.c
+++ b/builtin-merge-recursive.c
@@ -25,10 +25,8 @@ int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
 	struct commit *result;
 
 	init_merge_options(&o);
-	if (argv[0]) {
-		if (!suffixcmp(argv[0], "-subtree"))
-			o.recursive_variant = MERGE_RECURSIVE_SUBTREE;
-	}
+	if (argv[0] && !suffixcmp(argv[0], "-subtree"))
+		o.subtree_shift = "";
 
 	if (argc < 4)
 		usagef("%s <base>... -- <head> <remote> ...", argv[0]);
@@ -44,7 +42,9 @@ int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
 			else if (!strcmp(arg+2, "theirs"))
 				o.recursive_variant = MERGE_RECURSIVE_THEIRS;
 			else if (!strcmp(arg+2, "subtree"))
-				o.recursive_variant = MERGE_RECURSIVE_SUBTREE;
+				o.subtree_shift = "";
+			else if (!prefixcmp(arg+2, "subtree="))
+				o.subtree_shift = arg + 10;
 			else
 				die("Unknown option %s", arg);
 			continue;
diff --git a/builtin-merge.c b/builtin-merge.c
index 42f19e1..3aa7ea4 100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -578,7 +578,7 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 
 		init_merge_options(&o);
 		if (!strcmp(strategy, "subtree"))
-			o.recursive_variant = MERGE_RECURSIVE_SUBTREE;
+			o.subtree_shift = "";
 
 		for (x = 0; x < xopts_nr; x++) {
 			if (!strcmp(xopts[x], "ours"))
@@ -586,7 +586,9 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 			else if (!strcmp(xopts[x], "theirs"))
 				o.recursive_variant = MERGE_RECURSIVE_THEIRS;
 			else if (!strcmp(xopts[x], "subtree"))
-				o.recursive_variant = MERGE_RECURSIVE_SUBTREE;
+				o.subtree_shift = "";
+			else if (!prefixcmp(xopts[x], "subtree="))
+				o.subtree_shift = xopts[x]+8;
 			else
 				die("Unknown option for merge-recursive: -X%s", xopts[x]);
 		}
diff --git a/cache.h b/cache.h
index bf468e5..c6902d2 100644
--- a/cache.h
+++ b/cache.h
@@ -993,6 +993,7 @@ extern int diff_auto_refresh_index;
 
 /* match-trees.c */
 void shift_tree(const unsigned char *, const unsigned char *, unsigned char *, int);
+void shift_tree_by(const unsigned char *, const unsigned char *, unsigned char *, const char *);
 
 /*
  * whitespace rules.
diff --git a/match-trees.c b/match-trees.c
index 0fd6df7..26f7ed1 100644
--- a/match-trees.c
+++ b/match-trees.c
@@ -185,7 +185,7 @@ static void match_trees(const unsigned char *hash1,
  * tree object by replacing it with another tree "hash2".
  */
 static int splice_tree(const unsigned char *hash1,
-		       char *prefix,
+		       const char *prefix,
 		       const unsigned char *hash2,
 		       unsigned char *result)
 {
@@ -264,6 +264,13 @@ void shift_tree(const unsigned char *hash1,
 	char *del_prefix;
 	int add_score, del_score;
 
+	/*
+	 * NEEDSWORK: this limits the recursion depth to hardcoded
+	 * value '2' to avoid excessive overhead.
+	 */
+	if (!depth_limit)
+		depth_limit = 2;
+
 	add_score = del_score = score_trees(hash1, hash2);
 	add_prefix = xcalloc(1, 1);
 	del_prefix = xcalloc(1, 1);
@@ -301,3 +308,63 @@ void shift_tree(const unsigned char *hash1,
 
 	splice_tree(hash1, add_prefix, hash2, shifted);
 }
+
+/*
+ * The user says the trees will be shifted by this much.
+ * Unfortunately we cannot fundamentally tell which one to
+ * be prefixed, as recursive merge can work in either direction.
+ */
+void shift_tree_by(const unsigned char *hash1,
+		   const unsigned char *hash2,
+		   unsigned char *shifted,
+		   const char *shift_prefix)
+{
+	unsigned char sub1[20], sub2[20];
+	unsigned mode1, mode2;
+	unsigned candidate = 0;
+
+	/* Can hash2 be a tree at shift_prefix in tree hash1? */
+	if (!get_tree_entry(hash1, shift_prefix, sub1, &mode1) &&
+	    S_ISDIR(mode1))
+		candidate |= 1;
+
+	/* Can hash1 be a tree at shift_prefix in tree hash2? */
+	if (!get_tree_entry(hash2, shift_prefix, sub2, &mode2) &&
+	    S_ISDIR(mode2))
+		candidate |= 2;
+
+	if (candidate == 3) {
+		/* Both are plausible -- we need to evaluate the score */
+		int best_score = score_trees(hash1, hash2);
+		int score;
+
+		candidate = 0;
+		score = score_trees(sub1, hash2);
+		if (score > best_score) {
+			candidate = 1;
+			best_score = score;
+		}
+		score = score_trees(sub2, hash1);
+		if (score > best_score)
+			candidate = 2;
+	}
+
+	if (!candidate) {
+		/* Neither is plausible -- do not shift */
+		hashcpy(shifted, hash2);
+		return;
+	}
+
+	if (candidate == 1)
+		/*
+		 * shift tree2 down by adding shift_prefix above it
+		 * to match tree1.
+		 */
+		splice_tree(hash1, shift_prefix, hash2, shifted);
+	else
+		/*
+		 * shift tree2 up by removing shift_prefix from it
+		 * to match tree1.
+		 */
+		hashcpy(shifted, sub2);
+}
diff --git a/merge-recursive.c b/merge-recursive.c
index 82f24ac..0af77cf 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -21,15 +21,17 @@
 #include "merge-recursive.h"
 #include "dir.h"
 
-static struct tree *shift_tree_object(struct tree *one, struct tree *two)
+static struct tree *shift_tree_object(struct tree *one, struct tree *two,
+				      const char *subtree_shift)
 {
 	unsigned char shifted[20];
 
-	/*
-	 * NEEDSWORK: this limits the recursion depth to hardcoded
-	 * value '2' to avoid excessive overhead.
-	 */
-	shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
+	if (!*subtree_shift) {
+		shift_tree(one->object.sha1, two->object.sha1, shifted, 0);
+	} else {
+		shift_tree_by(one->object.sha1, two->object.sha1, shifted,
+			      subtree_shift);
+	}
 	if (!hashcmp(two->object.sha1, shifted))
 		return two;
 	return lookup_tree(shifted);
@@ -1213,9 +1215,9 @@ int merge_trees(struct merge_options *o,
 {
 	int code, clean;
 
-	if (o->recursive_variant == MERGE_RECURSIVE_SUBTREE) {
-		merge = shift_tree_object(head, merge);
-		common = shift_tree_object(head, common);
+	if (o->subtree_shift) {
+		merge = shift_tree_object(head, merge, o->subtree_shift);
+		common = shift_tree_object(head, common, o->subtree_shift);
 	}
 
 	if (sha_eq(common->object.sha1, merge->object.sha1)) {
diff --git a/merge-recursive.h b/merge-recursive.h
index 39de100..e63df9d 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -7,10 +7,11 @@ struct merge_options {
 	const char *branch1;
 	const char *branch2;
 	enum {
-		MERGE_RECURSIVE_SUBTREE = 1,
+		MERGE_RECURSIVE_NORMAL = 0,
 		MERGE_RECURSIVE_OURS,
 		MERGE_RECURSIVE_THEIRS,
 	} recursive_variant;
+	const char *subtree_shift;
 	unsigned buffer_output : 1;
 	int verbosity;
 	int diff_rename_limit;
-- 
cgit v0.10.2-6-g49f6


From e3cba962b172804ca1cab82801d94858154bd8cc Mon Sep 17 00:00:00 2001
From: Avery Pennarun <apenwarr@gmail.com>
Date: Wed, 25 Nov 2009 21:23:59 -0500
Subject: Extend merge-subtree tests to test -Xsubtree=dir.

This tests the configurable -Xsubtree feature of merge-recursive.

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/t/t6029-merge-subtree.sh b/t/t6029-merge-subtree.sh
index 5bbfa44..3900d9f 100755
--- a/t/t6029-merge-subtree.sh
+++ b/t/t6029-merge-subtree.sh
@@ -52,6 +52,7 @@ test_expect_success 'initial merge' '
 	git merge -s ours --no-commit gui/master &&
 	git read-tree --prefix=git-gui/ -u gui/master &&
 	git commit -m "Merge git-gui as our subdirectory" &&
+	git checkout -b work &&
 	git ls-files -s >actual &&
 	(
 		echo "100644 $o1 0	git-gui/git-gui.sh"
@@ -65,9 +66,10 @@ test_expect_success 'merge update' '
 	echo git-gui2 > git-gui.sh &&
 	o3=$(git hash-object git-gui.sh) &&
 	git add git-gui.sh &&
+	git checkout -b master2 &&
 	git commit -m "update git-gui" &&
 	cd ../git &&
-	git pull -s subtree gui master &&
+	git pull -s subtree gui master2 &&
 	git ls-files -s >actual &&
 	(
 		echo "100644 $o3 0	git-gui/git-gui.sh"
@@ -76,4 +78,47 @@ test_expect_success 'merge update' '
 	test_cmp expected actual
 '
 
+test_expect_success 'initial ambiguous subtree' '
+	cd ../git &&
+	git reset --hard master &&
+	git checkout -b master2 &&
+	git merge -s ours --no-commit gui/master &&
+	git read-tree --prefix=git-gui2/ -u gui/master &&
+	git commit -m "Merge git-gui2 as our subdirectory" &&
+	git checkout -b work2 &&
+	git ls-files -s >actual &&
+	(
+		echo "100644 $o1 0	git-gui/git-gui.sh"
+		echo "100644 $o1 0	git-gui2/git-gui.sh"
+		echo "100644 $o2 0	git.c"
+	) >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'merge using explicit' '
+	cd ../git &&
+	git reset --hard master2 &&
+	git pull -Xsubtree=git-gui gui master2 &&
+	git ls-files -s >actual &&
+	(
+		echo "100644 $o3 0	git-gui/git-gui.sh"
+		echo "100644 $o1 0	git-gui2/git-gui.sh"
+		echo "100644 $o2 0	git.c"
+	) >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'merge2 using explicit' '
+	cd ../git &&
+	git reset --hard master2 &&
+	git pull -Xsubtree=git-gui2 gui master2 &&
+	git ls-files -s >actual &&
+	(
+		echo "100644 $o1 0	git-gui/git-gui.sh"
+		echo "100644 $o3 0	git-gui2/git-gui.sh"
+		echo "100644 $o2 0	git.c"
+	) >expected &&
+	test_cmp expected actual
+'
+
 test_done
-- 
cgit v0.10.2-6-g49f6


From 566c511195adc0ce88559853f2f00933e241d862 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 18 Jul 2008 02:43:00 -0700
Subject: Document that merge strategies can now take their own options

Also document the recently added -Xtheirs, -Xours and -Xsubtree[=path]
options to the merge-recursive strategy.

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/merge-options.txt b/Documentation/merge-options.txt
index fec3394..22606f0 100644
--- a/Documentation/merge-options.txt
+++ b/Documentation/merge-options.txt
@@ -74,3 +74,8 @@ option can be used to override --squash.
 -v::
 --verbose::
 	Be verbose.
+
+-X <option>::
+--strategy-option=<option>::
+	Pass merge strategy specific option through to the merge
+	strategy.
diff --git a/Documentation/merge-strategies.txt b/Documentation/merge-strategies.txt
index 42910a3..a5bc1db 100644
--- a/Documentation/merge-strategies.txt
+++ b/Documentation/merge-strategies.txt
@@ -1,6 +1,11 @@
 MERGE STRATEGIES
 ----------------
 
+The merge mechanism ('git-merge' and 'git-pull' commands) allows the
+backend 'merge strategies' to be chosen with `-s` option.  Some strategies
+can also take their own options, which can be passed by giving `-X<option>`
+arguments to 'git-merge' and/or 'git-pull'.
+
 resolve::
 	This can only resolve two heads (i.e. the current branch
 	and another branch you pulled from) using a 3-way merge
@@ -20,6 +25,27 @@ recursive::
 	Additionally this can detect and handle merges involving
 	renames.  This is the default merge strategy when
 	pulling or merging one branch.
++
+The 'recursive' strategy can take the following options:
+
+ours;;
+	This option forces conflicting hunks to be auto-resolved cleanly by
+	favoring 'our' version.  Changes from the other tree that do not
+	conflict with our side are reflected to the merge result.
++
+This should not be confused with the 'ours' merge strategy, which does not
+even look at what the other tree contains at all.  It discards everything
+the other tree did, declaring 'our' history contains all that happened in it.
+
+theirs;;
+	This is opposite of 'ours'.
+
+subtree[=path];;
+	This option is a more advanced form of 'subtree' strategy, where
+	the strategy makes a guess on how two trees must be shifted to
+	match with each other when merging.  Instead, the specified path
+	is prefixed (or stripped from the beginning) to make the shape of
+	two trees to match.
 
 octopus::
 	This resolves cases with more than two heads, but refuses to do
@@ -33,7 +59,8 @@ ours::
 	merge is always that of the current branch head, effectively
 	ignoring all changes from all other branches.  It is meant to
 	be used to supersede old development history of side
-	branches.
+	branches.  Note that this is different from the -Xours option to
+	the 'recursive' merge strategy.
 
 subtree::
 	This is a modified recursive strategy. When merging trees A and
-- 
cgit v0.10.2-6-g49f6