Merge branch 'ag/merge-strategies-in-c' into seen

The resolve and octopus merge strategy backends have been rewritten
in C.

* ag/merge-strategies-in-c:
  sequencer: use the "octopus" merge strategy without forking
  sequencer: use the "resolve" strategy without forking
  merge: use the "octopus" strategy without forking
  merge: use the "resolve" strategy without forking
  merge-octopus: rewrite in C
  merge-recursive: move better_branch_name() to merge.c
  merge-resolve: rewrite in C
  merge-index: don't fork if the requested program is `git-merge-one-file'
  merge-index: libify merge_one_path() and merge_all()
  merge-one-file: rewrite in C
  t6027: modernise tests

Makefile

@@ -603,9 +603,6 @@ unexport CDPATH
 SCRIPT_SH += git-bisect.sh
 SCRIPT_SH += git-difftool--helper.sh
 SCRIPT_SH += git-filter-branch.sh
-SCRIPT_SH += git-merge-octopus.sh
-SCRIPT_SH += git-merge-one-file.sh
-SCRIPT_SH += git-merge-resolve.sh
 SCRIPT_SH += git-mergetool.sh
 SCRIPT_SH += git-quiltimport.sh
 SCRIPT_SH += git-request-pull.sh
@@ -924,6 +921,7 @@ LIB_OBJS += match-trees.o
 LIB_OBJS += mem-pool.o
 LIB_OBJS += merge-blobs.o
 LIB_OBJS += merge-recursive.o
+LIB_OBJS += merge-strategies.o
 LIB_OBJS += merge.o
 LIB_OBJS += mergesort.o
 LIB_OBJS += midx.o
@@ -1115,8 +1113,11 @@ BUILTIN_OBJS += builtin/mailsplit.o
 BUILTIN_OBJS += builtin/merge-base.o
 BUILTIN_OBJS += builtin/merge-file.o
 BUILTIN_OBJS += builtin/merge-index.o
+BUILTIN_OBJS += builtin/merge-octopus.o
+BUILTIN_OBJS += builtin/merge-one-file.o
 BUILTIN_OBJS += builtin/merge-ours.o
 BUILTIN_OBJS += builtin/merge-recursive.o
+BUILTIN_OBJS += builtin/merge-resolve.o
 BUILTIN_OBJS += builtin/merge-tree.o
 BUILTIN_OBJS += builtin/merge.o
 BUILTIN_OBJS += builtin/mktag.o

builtin.h

@@ -179,9 +179,12 @@ int cmd_maintenance(int argc, const char **argv, const char *prefix);
 int cmd_merge(int argc, const char **argv, const char *prefix);
 int cmd_merge_base(int argc, const char **argv, const char *prefix);
 int cmd_merge_index(int argc, const char **argv, const char *prefix);
+int cmd_merge_octopus(int argc, const char **argv, const char *prefix);
 int cmd_merge_ours(int argc, const char **argv, const char *prefix);
 int cmd_merge_file(int argc, const char **argv, const char *prefix);
+int cmd_merge_one_file(int argc, const char **argv, const char *prefix);
 int cmd_merge_recursive(int argc, const char **argv, const char *prefix);
+int cmd_merge_resolve(int argc, const char **argv, const char *prefix);
 int cmd_merge_tree(int argc, const char **argv, const char *prefix);
 int cmd_mktag(int argc, const char **argv, const char *prefix);
 int cmd_mktree(int argc, const char **argv, const char *prefix);

builtin/merge-index.c

 #define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "builtin.h"
-#include "run-command.h"
-
-static const char *pgm;
-static int one_shot, quiet;
-static int err;
-
-static int merge_entry(int pos, const char *path)
-{
-	int found;
-	const char *arguments[] = { pgm, "", "", "", path, "", "", "", NULL };
-	char hexbuf[4][GIT_MAX_HEXSZ + 1];
-	char ownbuf[4][60];
-
-	if (pos >= active_nr)
-		die("git merge-index: %s not in the cache", path);
-	found = 0;
-	do {
-		const struct cache_entry *ce = active_cache[pos];
-		int stage = ce_stage(ce);
-
-		if (strcmp(ce->name, path))
-			break;
-		found++;
-		oid_to_hex_r(hexbuf[stage], &ce->oid);
-		xsnprintf(ownbuf[stage], sizeof(ownbuf[stage]), "%o", ce->ce_mode);
-		arguments[stage] = hexbuf[stage];
-		arguments[stage + 4] = ownbuf[stage];
-	} while (++pos < active_nr);
-	if (!found)
-		die("git merge-index: %s not in the cache", path);
-
-	if (run_command_v_opt(arguments, 0)) {
-		if (one_shot)
-			err++;
-		else {
-			if (!quiet)
-				die("merge program failed");
-			exit(1);
-		}
-	}
-	return found;
-}
-
-static void merge_one_path(const char *path)
-{
-	int pos = cache_name_pos(path, strlen(path));
-
-	/*
-	 * If it already exists in the cache as stage0, it's
-	 * already merged and there is nothing to do.
-	 */
-	if (pos < 0)
-		merge_entry(-pos-1, path);
-}
-
-static void merge_all(void)
-{
-	int i;
-	for (i = 0; i < active_nr; i++) {
-		const struct cache_entry *ce = active_cache[i];
-		if (!ce_stage(ce))
-			continue;
-		i += merge_entry(i, ce->name)-1;
-	}
-}
+#include "lockfile.h"
+#include "merge-strategies.h"
 
 int cmd_merge_index(int argc, const char **argv, const char *prefix)
 {
-	int i, force_file = 0;
+	int i, force_file = 0, err = 0, one_shot = 0, quiet = 0;
+	const char *pgm;
+	void *data;
+	merge_cb merge_action;
+	struct lock_file lock = LOCK_INIT;
 
 	/* Without this we cannot rely on waitpid() to tell
 	 * what happened to our children.
@@ -89,7 +30,19 @@ int cmd_merge_index(int argc, const char **argv, const char *prefix)
 		quiet = 1;
 		i++;
 	}
+
 	pgm = argv[i++];
+	if (!strcmp(pgm, "git-merge-one-file")) {
+		merge_action = merge_one_file_cb;
+		data = (void *)the_repository;
+
+		setup_work_tree();
+		hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
+	} else {
+		merge_action = merge_program_cb;
+		data = (void *)pgm;
+	}
+
 	for (; i < argc; i++) {
 		const char *arg = argv[i];
 		if (!force_file && *arg == '-') {
@@ -98,14 +51,23 @@ int cmd_merge_index(int argc, const char **argv, const char *prefix)
 				continue;
 			}
 			if (!strcmp(arg, "-a")) {
-				merge_all();
+				err |= merge_all(&the_index, one_shot, quiet,
+						 merge_action, data);
 				continue;
 			}
 			die("git merge-index: unknown option %s", arg);
 		}
-		merge_one_path(arg);
+		err |= merge_one_path(&the_index, one_shot, quiet, arg,
+				      merge_action, data);
+	}
+
+	if (merge_action == merge_one_file_cb) {
+		if (err) {
+			rollback_lock_file(&lock);
+			return err;
+		}
+
+		return write_locked_index(&the_index, &lock, COMMIT_LOCK);
 	}
-	if (err && !quiet)
-		die("merge program failed");
 	return err;
 }

builtin/merge-octopus.c

+/*
+ * Builtin "git merge-octopus"
+ *
+ * Copyright (c) 2020 Alban Gruin
+ *
+ * Based on git-merge-octopus.sh, written by Junio C Hamano.
+ *
+ * Resolve two or more trees.
+ */
+
+#include "cache.h"
+#include "builtin.h"
+#include "commit.h"
+#include "merge-strategies.h"
+
+static const char builtin_merge_octopus_usage[] =
+	"git merge-octopus [<bases>...] -- <head> <remote1> <remote2> [<remotes>...]";
+
+int cmd_merge_octopus(int argc, const char **argv, const char *prefix)
+{
+	int i, sep_seen = 0;
+	struct commit_list *bases = NULL, *remotes = NULL;
+	struct commit_list **next_base = &bases, **next_remote = &remotes;
+	const char *head_arg = NULL;
+
+	if (argc < 5)
+		usage(builtin_merge_octopus_usage);
+
+	setup_work_tree();
+	if (repo_read_index(the_repository) < 0)
+		die("corrupted cache");
+
+	/*
+	 * The first parameters up to -- are merge bases; the rest are
+	 * heads.
+	 */
+	for (i = 1; i < argc; i++) {
+		if (strcmp(argv[i], "--") == 0)
+			sep_seen = 1;
+		else if (strcmp(argv[i], "-h") == 0)
+			usage(builtin_merge_octopus_usage);
+		else if (sep_seen && !head_arg)
+			head_arg = argv[i];
+		else {
+			struct object_id oid;
+
+			get_oid(argv[i], &oid);
+
+			if (!oideq(&oid, the_hash_algo->empty_tree)) {
+				struct commit *commit;
+				commit = lookup_commit_or_die(&oid, argv[i]);
+
+				if (sep_seen)
+					next_remote = commit_list_append(commit, next_remote);
+				else
+					next_base = commit_list_append(commit, next_base);
+			}
+		}
+	}
+
+	/*
+	 * Reject if this is not an octopus -- resolve should be used
+	 * instead.
+	 */
+	if (commit_list_count(remotes) < 2)
+		return 2;
+
+	return merge_strategies_octopus(the_repository, bases, head_arg, remotes);
+}

builtin/merge-one-file.c

+/*
+ * Builtin "git merge-one-file"
+ *
+ * Copyright (c) 2020 Alban Gruin
+ *
+ * Based on git-merge-one-file.sh, written by Linus Torvalds.
+ *
+ * This is the git per-file merge utility, called with
+ *
+ *   argv[1] - original file SHA1 (or empty)
+ *   argv[2] - file in branch1 SHA1 (or empty)
+ *   argv[3] - file in branch2 SHA1 (or empty)
+ *   argv[4] - pathname in repository
+ *   argv[5] - original file mode (or empty)
+ *   argv[6] - file in branch1 mode (or empty)
+ *   argv[7] - file in branch2 mode (or empty)
+ *
+ * Handle some trivial cases. The _really_ trivial cases have been
+ * handled already by git read-tree, but that one doesn't do any merges
+ * that might change the tree layout.
+ */
+
+#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#include "cache.h"
+#include "builtin.h"
+#include "lockfile.h"
+#include "merge-strategies.h"
+
+static const char builtin_merge_one_file_usage[] =
+	"git merge-one-file <orig blob> <our blob> <their blob> <path> "
+	"<orig mode> <our mode> <their mode>\n\n"
+	"Blob ids and modes should be empty for missing files.";
+
+static int read_mode(const char *name, const char *arg, unsigned int *mode)
+{
+	char *last;
+	int ret = 0;
+
+	*mode = strtol(arg, &last, 8);
+
+	if (*last)
+		ret = error(_("invalid '%s' mode: expected nothing, got '%c'"), name, *last);
+	else if (!(S_ISREG(*mode) || S_ISDIR(*mode) || S_ISLNK(*mode)))
+		ret = error(_("invalid '%s' mode: %o"), name, *mode);
+
+	return ret;
+}
+
+int cmd_merge_one_file(int argc, const char **argv, const char *prefix)
+{
+	struct object_id orig_blob, our_blob, their_blob,
+		*p_orig_blob = NULL, *p_our_blob = NULL, *p_their_blob = NULL;
+	unsigned int orig_mode = 0, our_mode = 0, their_mode = 0, ret = 0;
+	struct lock_file lock = LOCK_INIT;
+
+	if (argc != 8)
+		usage(builtin_merge_one_file_usage);
+
+	if (read_cache() < 0)
+		die("invalid index");
+
+	hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
+
+	if (!get_oid(argv[1], &orig_blob)) {
+		p_orig_blob = &orig_blob;
+		ret = read_mode("orig", argv[5], &orig_mode);
+	}
+
+	if (!get_oid(argv[2], &our_blob)) {
+		p_our_blob = &our_blob;
+		ret = read_mode("our", argv[6], &our_mode);
+	}
+
+	if (!get_oid(argv[3], &their_blob)) {
+		p_their_blob = &their_blob;
+		ret = read_mode("their", argv[7], &their_mode);
+	}
+
+	if (ret)
+		return ret;
+
+	ret = merge_strategies_one_file(the_repository,
+					p_orig_blob, p_our_blob, p_their_blob, argv[4],
+					orig_mode, our_mode, their_mode);
+
+	if (ret) {
+		rollback_lock_file(&lock);
+		return !!ret;
+	}
+
+	return write_locked_index(&the_index, &lock, COMMIT_LOCK);
+}

builtin/merge-recursive.c

@@ -8,18 +8,6 @@
 static const char builtin_merge_recursive_usage[] =
 	"git %s <base>... -- <head> <remote> ...";
 
-static char *better_branch_name(const char *branch)
-{
-	static char githead_env[8 + GIT_MAX_HEXSZ + 1];
-	char *name;
-
-	if (strlen(branch) != the_hash_algo->hexsz)
-		return xstrdup(branch);
-	xsnprintf(githead_env, sizeof(githead_env), "GITHEAD_%s", branch);
-	name = getenv(githead_env);
-	return xstrdup(name ? name : branch);
-}
-
 int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
 {
 	const struct object_id *bases[21];
@@ -75,8 +63,8 @@ int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
 	if (get_oid(o.branch2, &h2))
 		die(_("could not resolve ref '%s'"), o.branch2);
 
-	o.branch1 = better1 = better_branch_name(o.branch1);
-	o.branch2 = better2 = better_branch_name(o.branch2);
+	o.branch1 = better1 = merge_get_better_branch_name(o.branch1);
+	o.branch2 = better2 = merge_get_better_branch_name(o.branch2);
 
 	if (o.verbosity >= 3)
 		printf(_("Merging %s with %s\n"), o.branch1, o.branch2);

builtin/merge-resolve.c

+/*
+ * Builtin "git merge-resolve"
+ *
+ * Copyright (c) 2020 Alban Gruin
+ *
+ * Based on git-merge-resolve.sh, written by Linus Torvalds and Junio C
+ * Hamano.
+ *
+ * Resolve two trees, using enhanced multi-base read-tree.
+ */
+
+#include "cache.h"
+#include "builtin.h"
+#include "merge-strategies.h"
+
+static const char builtin_merge_resolve_usage[] =
+	"git merge-resolve <bases>... -- <head> <remote>";
+
+int cmd_merge_resolve(int argc, const char **argv, const char *prefix)
+{
+	int i, is_baseless = 1, sep_seen = 0;
+	const char *head = NULL;
+	struct commit_list *bases = NULL, *remote = NULL;
+	struct commit_list **next_base = &bases;
+
+	if (argc < 5)
+		usage(builtin_merge_resolve_usage);
+
+	setup_work_tree();
+	if (repo_read_index(the_repository) < 0)
+		die("invalid index");
+
+	/* The first parameters up to -- are merge bases; the rest are
+	 * heads. */
+	for (i = 1; i < argc; i++) {
+		if (strcmp(argv[i], "--") == 0)
+			sep_seen = 1;
+		else if (strcmp(argv[i], "-h") == 0)
+			usage(builtin_merge_resolve_usage);
+		else if (sep_seen && !head)
+			head = argv[i];
+		else if (remote) {
+			/* Give up if we are given two or more remotes.
+			 * Not handling octopus. */
+			return 2;
+		} else {
+			struct object_id oid;
+
+			get_oid(argv[i], &oid);
+			is_baseless &= sep_seen;
+
+			if (!oideq(&oid, the_hash_algo->empty_tree)) {
+				struct commit *commit;
+				commit = lookup_commit_or_die(&oid, argv[i]);
+
+				if (sep_seen)
+					commit_list_append(commit, &remote);
+				else
+					next_base = commit_list_append(commit, next_base);
+			}
+		}
+	}
+
+	/* Give up if this is a baseless merge. */
+	if (is_baseless)
+		return 2;
+
+	return merge_strategies_resolve(the_repository, bases, head, remote);
+}

builtin/merge.c

@@ -41,6 +41,7 @@
 #include "commit-reach.h"
 #include "wt-status.h"
 #include "commit-graph.h"
+#include "merge-strategies.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)
@@ -740,7 +741,13 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 				       COMMIT_LOCK | SKIP_IF_UNCHANGED))
 			die(_("unable to write %s"), get_index_file());
 		return clean ? 0 : 1;
-	} else {
+	} else if (!strcmp(strategy, "resolve"))
+		return merge_strategies_resolve(the_repository, common,
+						head_arg, remoteheads);
+	else if (!strcmp(strategy, "octopus"))
+		return merge_strategies_octopus(the_repository, common,
+						head_arg, remoteheads);
+	else {
 		return try_merge_command(the_repository,
 					 strategy, xopts_nr, xopts,
 					 common, head_arg, remoteheads);

cache.h

@@ -1904,7 +1904,7 @@ int checkout_fast_forward(struct repository *r,
 			  const struct object_id *from,
 			  const struct object_id *to,
 			  int overwrite_ignore);
-
+char *merge_get_better_branch_name(const char *branch);
 
 int sane_execvp(const char *file, char *const argv[]);
 

git-merge-octopus.sh

-#!/bin/sh
-#
-# Copyright (c) 2005 Junio C Hamano
-#
-# Resolve two or more trees.
-#
-
-. git-sh-setup
-
-LF='
-'
-
-# The first parameters up to -- are merge bases; the rest are heads.
-bases= head= remotes= sep_seen=
-for arg
-do
-	case ",$sep_seen,$head,$arg," in
-	*,--,)
-		sep_seen=yes
-		;;
-	,yes,,*)
-		head=$arg
-		;;
-	,yes,*)
-		remotes="$remotes$arg "
-		;;
-	*)
-		bases="$bases$arg "
-		;;
-	esac
-done
-
-# Reject if this is not an octopus -- resolve should be used instead.
-case "$remotes" in
-?*' '?*)
-	;;
-*)
-	exit 2 ;;
-esac
-
-# MRC is the current "merge reference commit"
-# MRT is the current "merge result tree"
-
-if ! git diff-index --quiet --cached HEAD --
-then
-    gettextln "Error: Your local changes to the following files would be overwritten by merge"
-    git diff-index --cached --name-only HEAD -- | sed -e 's/^/    /'
-    exit 2
-fi
-MRC=$(git rev-parse --verify -q $head)
-MRT=$(git write-tree)
-NON_FF_MERGE=0
-OCTOPUS_FAILURE=0
-for SHA1 in $remotes
-do
-	case "$OCTOPUS_FAILURE" in
-	1)
-		# We allow only last one to have a hand-resolvable
-		# conflicts.  Last round failed and we still had
-		# a head to merge.
-		gettextln "Automated merge did not work."
-		gettextln "Should not be doing an octopus."
-		exit 2
-	esac
-
-	eval pretty_name=\${GITHEAD_$SHA1:-$SHA1}
-	if test "$SHA1" = "$pretty_name"
-	then
-		SHA1_UP="$(echo "$SHA1" | tr a-z A-Z)"
-		eval pretty_name=\${GITHEAD_$SHA1_UP:-$pretty_name}
-	fi
-	common=$(git merge-base --all $SHA1 $MRC) ||
-		die "$(eval_gettext "Unable to find common commit with \$pretty_name")"
-
-	case "$LF$common$LF" in
-	*"$LF$SHA1$LF"*)
-		eval_gettextln "Already up to date with \$pretty_name"
-		continue
-		;;
-	esac
-
-	if test "$common,$NON_FF_MERGE" = "$MRC,0"
-	then
-		# The first head being merged was a fast-forward.
-		# Advance MRC to the head being merged, and use that
-		# tree as the intermediate result of the merge.
-		# We still need to count this as part of the parent set.
-
-		eval_gettextln "Fast-forwarding to: \$pretty_name"
-		git read-tree -u -m $head $SHA1 || exit
-		MRC=$SHA1 MRT=$(git write-tree)
-		continue
-	fi
-
-	NON_FF_MERGE=1
-
-	eval_gettextln "Trying simple merge with \$pretty_name"
-	git read-tree -u -m --aggressive  $common $MRT $SHA1 || exit 2
-	next=$(git write-tree 2>/dev/null)
-	if test $? -ne 0
-	then
-		gettextln "Simple merge did not work, trying automatic merge."
-		git merge-index -o git-merge-one-file -a ||
-		OCTOPUS_FAILURE=1
-		next=$(git write-tree 2>/dev/null)
-	fi
-
-	MRC="$MRC $SHA1"
-	MRT=$next
-done
-
-exit "$OCTOPUS_FAILURE"

git-merge-one-file.sh

-#!/bin/sh
-#
-# Copyright (c) Linus Torvalds, 2005
-#
-# This is the git per-file merge script, called with
-#
-#   $1 - original file SHA1 (or empty)
-#   $2 - file in branch1 SHA1 (or empty)
-#   $3 - file in branch2 SHA1 (or empty)
-#   $4 - pathname in repository
-#   $5 - original file mode (or empty)
-#   $6 - file in branch1 mode (or empty)
-#   $7 - file in branch2 mode (or empty)
-#
-# Handle some trivial cases.. The _really_ trivial cases have
-# been handled already by git read-tree, but that one doesn't
-# do any merges that might change the tree layout.
-
-USAGE='<orig blob> <our blob> <their blob> <path>'
-USAGE="$USAGE <orig mode> <our mode> <their mode>"
-LONG_USAGE="usage: git merge-one-file $USAGE
-
-Blob ids and modes should be empty for missing files."
-
-SUBDIRECTORY_OK=Yes
-. git-sh-setup
-cd_to_toplevel
-require_work_tree
-
-if test $# != 7
-then
-	echo "$LONG_USAGE"
-	exit 1
-fi
-
-case "${1:-.}${2:-.}${3:-.}" in
-#
-# Deleted in both or deleted in one and unchanged in the other
-#
-"$1.." | "$1.$1" | "$1$1.")
-	if { test -z "$6" && test "$5" != "$7"; } ||
-	   { test -z "$7" && test "$5" != "$6"; }
-	then
-		echo "ERROR: File $4 deleted on one branch but had its" >&2
-		echo "ERROR: permissions changed on the other." >&2
-		exit 1
-	fi
-
-	if test -n "$2"
-	then
-		echo "Removing $4"
-	else
-		# read-tree checked that index matches HEAD already,
-		# so we know we do not have this path tracked.
-		# there may be an unrelated working tree file here,
-		# which we should just leave unmolested.  Make sure
-		# we do not have it in the index, though.
-		exec git update-index --remove -- "$4"
-	fi
-	if test -f "$4"
-	then
-		rm -f -- "$4" &&
-		rmdir -p "$(expr "z$4" : 'z\(.*\)/')" 2>/dev/null || :
-	fi &&
-		exec git update-index --remove -- "$4"
-	;;
-
-#
-# Added in one.
-#
-".$2.")
-	# the other side did not add and we added so there is nothing
-	# to be done, except making the path merged.
-	exec git update-index --add --cacheinfo "$6" "$2" "$4"
-	;;
-"..$3")
-	echo "Adding $4"
-	if test -f "$4"
-	then
-		echo "ERROR: untracked $4 is overwritten by the merge." >&2
-		exit 1
-	fi
-	git update-index --add --cacheinfo "$7" "$3" "$4" &&
-		exec git checkout-index -u -f -- "$4"
-	;;
-
-#
-# Added in both, identically (check for same permissions).
-#
-".$3$2")
-	if test "$6" != "$7"
-	then
-		echo "ERROR: File $4 added identically in both branches," >&2
-		echo "ERROR: but permissions conflict $6->$7." >&2
-		exit 1
-	fi
-	echo "Adding $4"
-	git update-index --add --cacheinfo "$6" "$2" "$4" &&
-		exec git checkout-index -u -f -- "$4"
-	;;
-
-#
-# Modified in both, but differently.
-#
-"$1$2$3" | ".$2$3")
-
-	case ",$6,$7," in
-	*,120000,*)
-		echo "ERROR: $4: Not merging symbolic link changes." >&2
-		exit 1
-		;;
-	*,160000,*)
-		echo "ERROR: $4: Not merging conflicting submodule changes." >&2
-		exit 1
-		;;
-	esac
-
-	src1=$(git unpack-file $2)
-	src2=$(git unpack-file $3)
-	case "$1" in
-	'')
-		echo "Added $4 in both, but differently."
-		orig=$(git unpack-file $(git hash-object /dev/null))
-		;;
-	*)
-		echo "Auto-merging $4"
-		orig=$(git unpack-file $1)
-		;;
-	esac
-
-	git merge-file "$src1" "$orig" "$src2"
-	ret=$?
-	msg=
-	if test $ret != 0 || test -z "$1"
-	then
-		msg='content conflict'
-		ret=1
-	fi
-
-	# Create the working tree file, using "our tree" version from the
-	# index, and then store the result of the merge.
-	git checkout-index -f --stage=2 -- "$4" && cat "$src1" >"$4" || exit 1
-	rm -f -- "$orig" "$src1" "$src2"
-
-	if test "$6" != "$7"
-	then
-		if test -n "$msg"
-		then
-			msg="$msg, "
-		fi
-		msg="${msg}permissions conflict: $5->$6,$7"
-		ret=1
-	fi
-
-	if test $ret != 0
-	then
-		echo "ERROR: $msg in $4" >&2
-		exit 1
-	fi
-	exec git update-index -- "$4"
-	;;
-
-*)
-	echo "ERROR: $4: Not handling case $1 -> $2 -> $3" >&2
-	;;
-esac
-exit 1

git-merge-resolve.sh

-#!/bin/sh
-#
-# Copyright (c) 2005 Linus Torvalds
-# Copyright (c) 2005 Junio C Hamano
-#
-# Resolve two trees, using enhanced multi-base read-tree.
-
-# The first parameters up to -- are merge bases; the rest are heads.
-bases= head= remotes= sep_seen=
-for arg
-do
-	case ",$sep_seen,$head,$arg," in
-	*,--,)
-		sep_seen=yes
-		;;
-	,yes,,*)
-		head=$arg
-		;;
-	,yes,*)
-		remotes="$remotes$arg "
-		;;
-	*)
-		bases="$bases$arg "
-		;;
-	esac
-done
-
-# Give up if we are given two or more remotes -- not handling octopus.
-case "$remotes" in
-?*' '?*)
-	exit 2 ;;
-esac
-
-# Give up if this is a baseless merge.
-if test '' = "$bases"
-then
-	exit 2
-fi
-
-git update-index -q --refresh
-git read-tree -u -m --aggressive $bases $head $remotes || exit 2
-echo "Trying simple merge."
-if result_tree=$(git write-tree 2>/dev/null)
-then
-	exit 0
-else
-	echo "Simple merge failed, trying Automatic merge."
-	if git merge-index -o git-merge-one-file -a
-	then
-		exit 0
-	else
-		exit 1
-	fi
-fi

git.c

@@ -548,10 +548,13 @@ static struct cmd_struct commands[] = {
 	{ "merge-base", cmd_merge_base, RUN_SETUP },
 	{ "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 	{ "merge-index", cmd_merge_index, RUN_SETUP | NO_PARSEOPT },
+	{ "merge-octopus", cmd_merge_octopus, RUN_SETUP | NO_PARSEOPT },
 	{ "merge-ours", cmd_merge_ours, RUN_SETUP | NO_PARSEOPT },
+	{ "merge-one-file", cmd_merge_one_file, RUN_SETUP | NEED_WORK_TREE | NO_PARSEOPT },
 	{ "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE | NO_PARSEOPT },
 	{ "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE | NO_PARSEOPT },
 	{ "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE | NO_PARSEOPT },
+	{ "merge-resolve", cmd_merge_resolve, RUN_SETUP | NEED_WORK_TREE | NO_PARSEOPT },
 	{ "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE | NO_PARSEOPT },
 	{ "merge-tree", cmd_merge_tree, RUN_SETUP | NO_PARSEOPT },
 	{ "mktag", cmd_mktag, RUN_SETUP | NO_PARSEOPT },

merge-strategies.c

+#include "cache.h"
+#include "cache-tree.h"
+#include "commit-reach.h"
+#include "dir.h"
+#include "entry.h"
+#include "ll-merge.h"
+#include "lockfile.h"
+#include "merge-strategies.h"
+#include "run-command.h"
+#include "unpack-trees.h"
+#include "xdiff-interface.h"
+
+static int add_to_index_cacheinfo(struct index_state *istate,
+				  unsigned int mode,
+				  const struct object_id *oid, const char *path)
+{
+	struct cache_entry *ce;
+	int len, option;
+
+	if (!verify_path(path, mode))
+		return error(_("Invalid path '%s'"), path);
+
+	len = strlen(path);
+	ce = make_empty_cache_entry(istate, len);
+
+	oidcpy(&ce->oid, oid);
+	memcpy(ce->name, path, len);
+	ce->ce_flags = create_ce_flags(0);
+	ce->ce_namelen = len;
+	ce->ce_mode = create_ce_mode(mode);
+	if (assume_unchanged)
+		ce->ce_flags |= CE_VALID;
+	option = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
+	if (add_index_entry(istate, ce, option))
+		return error(_("%s: cannot add to the index"), path);
+
+	return 0;
+}
+
+static int checkout_from_index(struct index_state *istate, const char *path)
+{
+	struct checkout state = CHECKOUT_INIT;
+	struct cache_entry *ce;
+
+	state.istate = istate;
+	state.force = 1;
+	state.base_dir = "";
+	state.base_dir_len = 0;
+
+	ce = index_file_exists(istate, path, strlen(path), 0);
+	if (checkout_entry(ce, &state, NULL, NULL) < 0)
+		return error(_("%s: cannot checkout file"), path);
+	return 0;
+}
+
+static int merge_one_file_deleted(struct index_state *istate,
+				  const struct object_id *orig_blob,
+				  const struct object_id *our_blob,
+				  const struct object_id *their_blob, const char *path,
+				  unsigned int orig_mode, unsigned int our_mode, unsigned int their_mode)
+{
+	if ((our_blob && orig_mode != our_mode) ||
+	    (their_blob && orig_mode != their_mode))
+		return error(_("File %s deleted on one branch but had its "
+			       "permissions changed on the other."), path);
+
+	if (our_blob) {
+		printf(_("Removing %s\n"), path);
+
+		if (file_exists(path))
+			remove_path(path);
+	}
+
+	if (remove_file_from_index(istate, path))
+		return error("%s: cannot remove from the index", path);
+	return 0;
+}
+
+static int do_merge_one_file(struct index_state *istate,
+			     const struct object_id *orig_blob,
+			     const struct object_id *our_blob,
+			     const struct object_id *their_blob, const char *path,
+			     unsigned int orig_mode, unsigned int our_mode, unsigned int their_mode)
+{
+	int ret, i, dest;
+	ssize_t written;
+	mmbuffer_t result = {NULL, 0};
+	mmfile_t mmfs[3];
+	struct ll_merge_options merge_opts = {0};
+	struct cache_entry *ce;
+
+	if (our_mode == S_IFLNK || their_mode == S_IFLNK)
+		return error(_("%s: Not merging symbolic link changes."), path);
+	else if (our_mode == S_IFGITLINK || their_mode == S_IFGITLINK)
+		return error(_("%s: Not merging conflicting submodule changes."), path);
+
+	read_mmblob(mmfs + 1, our_blob);
+	read_mmblob(mmfs + 2, their_blob);
+
+	if (orig_blob) {
+		printf(_("Auto-merging %s\n"), path);
+		read_mmblob(mmfs + 0, orig_blob);
+	} else {
+		printf(_("Added %s in both, but differently.\n"), path);
+		read_mmblob(mmfs + 0, &null_oid);
+	}
+
+	merge_opts.xdl_opts = XDL_MERGE_ZEALOUS_ALNUM;
+	ret = ll_merge(&result, path,
+		       mmfs + 0, "orig",
+		       mmfs + 1, "our",
+		       mmfs + 2, "their",
+		       istate, &merge_opts);
+
+	for (i = 0; i < 3; i++)
+		free(mmfs[i].ptr);
+
+	if (ret < 0) {
+		free(result.ptr);
+		return error(_("Failed to execute internal merge"));
+	}
+
+	/*
+	 * Create the working tree file, using "our tree" version from
+	 * the index, and then store the result of the merge.
+	 */
+	ce = index_file_exists(istate, path, strlen(path), 0);
+	if (!ce)
+		BUG("file is not present in the cache?");
+
+	unlink(path);
+	if ((dest = open(path, O_WRONLY | O_CREAT, ce->ce_mode)) < 0) {
+		free(result.ptr);
+		return error_errno(_("failed to open file '%s'"), path);
+	}
+
+	written = write_in_full(dest, result.ptr, result.size);
+	close(dest);
+
+	free(result.ptr);
+
+	if (written < 0)
+		return error_errno(_("failed to write to '%s'"), path);
+
+	if (ret != 0 || !orig_blob)
+		ret = error(_("content conflict in %s"), path);
+	if (our_mode != their_mode)
+		return error(_("permission conflict: %o->%o,%o in %s"),
+			     orig_mode, our_mode, their_mode, path);
+	if (ret)
+		return -1;
+
+	return add_file_to_index(istate, path, 0);
+}
+
+int merge_strategies_one_file(struct repository *r,
+			      const struct object_id *orig_blob,
+			      const struct object_id *our_blob,
+			      const struct object_id *their_blob, const char *path,
+			      unsigned int orig_mode, unsigned int our_mode,
+			      unsigned int their_mode)
+{
+	if (orig_blob &&
+	    ((!their_blob && our_blob && oideq(orig_blob, our_blob)) ||
+	     (!our_blob && their_blob && oideq(orig_blob, their_blob))))
+		/* Deleted in both or deleted in one and unchanged in the other. */
+		return merge_one_file_deleted(r->index,
+					      orig_blob, our_blob, their_blob, path,
+					      orig_mode, our_mode, their_mode);
+	else if (!orig_blob && our_blob && !their_blob) {
+		/*
+		 * Added in one.  The other side did not add and we
+		 * added so there is nothing to be done, except making
+		 * the path merged.
+		 */
+		return add_to_index_cacheinfo(r->index, our_mode, our_blob, path);
+	} else if (!orig_blob && !our_blob && their_blob) {
+		printf(_("Adding %s\n"), path);
+
+		if (file_exists(path))
+			return error(_("untracked %s is overwritten by the merge."), path);
+
+		if (add_to_index_cacheinfo(r->index, their_mode, their_blob, path))
+			return -1;
+		return checkout_from_index(r->index, path);
+	} else if (!orig_blob && our_blob && their_blob &&
+		   oideq(our_blob, their_blob)) {
+		/* Added in both, identically (check for same permissions). */
+		if (our_mode != their_mode)
+			return error(_("File %s added identically in both branches, "
+				       "but permissions conflict %o->%o."),
+				     path, our_mode, their_mode);
+
+		printf(_("Adding %s\n"), path);
+
+		if (add_to_index_cacheinfo(r->index, our_mode, our_blob, path))
+			return -1;
+		return checkout_from_index(r->index, path);
+	} else if (our_blob && their_blob)
+		/* Modified in both, but differently. */
+		return do_merge_one_file(r->index,
+					 orig_blob, our_blob, their_blob, path,
+					 orig_mode, our_mode, their_mode);
+	else {
+		char orig_hex[GIT_MAX_HEXSZ] = {0}, our_hex[GIT_MAX_HEXSZ] = {0},
+			their_hex[GIT_MAX_HEXSZ] = {0};
+
+		if (orig_blob)
+			oid_to_hex_r(orig_hex, orig_blob);
+		if (our_blob)
+			oid_to_hex_r(our_hex, our_blob);
+		if (their_blob)
+			oid_to_hex_r(their_hex, their_blob);
+
+		return error(_("%s: Not handling case %s -> %s -> %s"),
+			     path, orig_hex, our_hex, their_hex);
+	}
+
+	return 0;
+}
+
+int merge_one_file_cb(const struct object_id *orig_blob,
+		      const struct object_id *our_blob,
+		      const struct object_id *their_blob, const char *path,
+		      unsigned int orig_mode, unsigned int our_mode, unsigned int their_mode,
+		      void *data)
+{
+	return merge_strategies_one_file((struct repository *)data,
+					 orig_blob, our_blob, their_blob, path,
+					 orig_mode, our_mode, their_mode);
+}
+
+int merge_program_cb(const struct object_id *orig_blob,
+		     const struct object_id *our_blob,
+		     const struct object_id *their_blob, const char *path,
+		     unsigned int orig_mode, unsigned int our_mode, unsigned int their_mode,
+		     void *data)
+{
+	char ownbuf[3][GIT_MAX_HEXSZ] = {{0}};
+	const char *arguments[] = { (char *)data, "", "", "", path,
+				    ownbuf[0], ownbuf[1], ownbuf[2],
+				    NULL };
+
+	if (orig_blob)
+		arguments[1] = oid_to_hex(orig_blob);
+	if (our_blob)
+		arguments[2] = oid_to_hex(our_blob);
+	if (their_blob)
+		arguments[3] = oid_to_hex(their_blob);
+
+	xsnprintf(ownbuf[0], sizeof(ownbuf[0]), "%o", orig_mode);
+	xsnprintf(ownbuf[1], sizeof(ownbuf[1]), "%o", our_mode);
+	xsnprintf(ownbuf[2], sizeof(ownbuf[2]), "%o", their_mode);
+
+	return run_command_v_opt(arguments, 0);
+}
+
+static int merge_entry(struct index_state *istate, int quiet, int pos,
+		       const char *path, merge_cb cb, void *data)
+{
+	int found = 0;
+	const struct object_id *oids[3] = {NULL};
+	unsigned int modes[3] = {0};
+
+	do {
+		const struct cache_entry *ce = istate->cache[pos];
+		int stage = ce_stage(ce);
+
+		if (strcmp(ce->name, path))
+			break;
+		found++;
+		oids[stage - 1] = &ce->oid;
+		modes[stage - 1] = ce->ce_mode;
+	} while (++pos < istate->cache_nr);
+	if (!found)
+		return error(_("%s is not in the cache"), path);
+
+	if (cb(oids[0], oids[1], oids[2], path, modes[0], modes[1], modes[2], data)) {
+		if (!quiet)
+			error(_("Merge program failed"));
+		return -2;
+	}
+
+	return found;
+}
+
+int merge_one_path(struct index_state *istate, int oneshot, int quiet,
+		   const char *path, merge_cb cb, void *data)
+{
+	int pos = index_name_pos(istate, path, strlen(path)), ret;
+
+	/*
+	 * If it already exists in the cache as stage0, it's
+	 * already merged and there is nothing to do.
+	 */
+	if (pos < 0) {
+		ret = merge_entry(istate, quiet, -pos - 1, path, cb, data);
+		if (ret == -1)
+			return -1;
+		else if (ret == -2)
+			return 1;
+	}
+	return 0;
+}
+
+int merge_all(struct index_state *istate, int oneshot, int quiet,
+	      merge_cb cb, void *data)
+{
+	int err = 0, i, ret;
+	for (i = 0; i < istate->cache_nr; i++) {
+		const struct cache_entry *ce = istate->cache[i];
+		if (!ce_stage(ce))
+			continue;
+
+		ret = merge_entry(istate, quiet, i, ce->name, cb, data);
+		if (ret > 0)
+			i += ret - 1;
+		else if (ret == -1)
+			return -1;
+		else if (ret == -2) {
+			if (oneshot)
+				err++;
+			else
+				return 1;
+		}
+	}
+
+	return err;
+}
+
+static int add_tree(const struct object_id *oid, struct tree_desc *t)
+{
+	struct tree *tree;
+
+	tree = parse_tree_indirect(oid);
+	if (parse_tree(tree))
+		return -1;
+
+	init_tree_desc(t, tree->buffer, tree->size);
+	return 0;
+}
+
+int merge_strategies_resolve(struct repository *r,
+			     struct commit_list *bases, const char *head_arg,
+			     struct commit_list *remote)
+{
+	int i = 0;
+	struct lock_file lock = LOCK_INIT;
+	struct tree_desc t[MAX_UNPACK_TREES];
+	struct unpack_trees_options opts;
+	struct object_id head, oid;
+	struct commit_list *j;
+
+	if (head_arg)
+		get_oid(head_arg, &head);
+
+	repo_hold_locked_index(r, &lock, LOCK_DIE_ON_ERROR);
+	refresh_index(r->index, 0, NULL, NULL, NULL);
+
+	memset(&opts, 0, sizeof(opts));
+	opts.head_idx = 1;
+	opts.src_index = r->index;
+	opts.dst_index = r->index;
+	opts.update = 1;
+	opts.merge = 1;
+	opts.aggressive = 1;
+
+	for (j = bases; j && j->item; j = j->next) {
+		if (add_tree(&j->item->object.oid, t + (i++)))
+			goto out;
+	}
+
+	if (head_arg && add_tree(&head, t + (i++)))
+		goto out;
+	if (remote && add_tree(&remote->item->object.oid, t + (i++)))
+		goto out;
+
+	if (i == 1)
+		opts.fn = oneway_merge;
+	else if (i == 2) {
+		opts.fn = twoway_merge;
+		opts.initial_checkout = is_index_unborn(r->index);
+	} else if (i >= 3) {
+		opts.fn = threeway_merge;
+		opts.head_idx = i - 1;
+	}
+
+	if (unpack_trees(i, t, &opts))
+		goto out;
+
+	puts(_("Trying simple merge."));
+	write_locked_index(r->index, &lock, COMMIT_LOCK);
+
+	if (write_index_as_tree(&oid, r->index, r->index_file,
+				WRITE_TREE_SILENT, NULL)) {
+		int ret;
+
+		puts(_("Simple merge failed, trying Automatic merge."));
+		repo_hold_locked_index(r, &lock, LOCK_DIE_ON_ERROR);
+		ret = merge_all(r->index, 0, 0, merge_one_file_cb, r);
+
+		write_locked_index(r->index, &lock, COMMIT_LOCK);
+		return !!ret;
+	}
+
+	return 0;
+
+ out:
+	rollback_lock_file(&lock);
+	return 2;
+}
+
+static int fast_forward(struct repository *r, const struct object_id *oids,
+			int nr, int aggressive)
+{
+	int i;
+	struct tree_desc t[MAX_UNPACK_TREES];
+	struct unpack_trees_options opts;
+	struct lock_file lock = LOCK_INIT;
+
+	repo_read_index_preload(r, NULL, 0);
+	if (refresh_index(r->index, REFRESH_QUIET, NULL, NULL, NULL))
+		return -1;
+
+	repo_hold_locked_index(r, &lock, LOCK_DIE_ON_ERROR);
+
+	memset(&opts, 0, sizeof(opts));
+	opts.head_idx = 1;
+	opts.src_index = r->index;
+	opts.dst_index = r->index;
+	opts.merge = 1;
+	opts.update = 1;
+	opts.aggressive = aggressive;
+
+	for (i = 0; i < nr; i++) {
+		struct tree *tree;
+		tree = parse_tree_indirect(oids + i);
+		if (parse_tree(tree))
+			return -1;
+		init_tree_desc(t + i, tree->buffer, tree->size);
+	}
+
+	if (nr == 1)
+		opts.fn = oneway_merge;
+	else if (nr == 2) {
+		opts.fn = twoway_merge;
+		opts.initial_checkout = is_index_unborn(r->index);
+	} else if (nr >= 3) {
+		opts.fn = threeway_merge;
+		opts.head_idx = nr - 1;
+	}
+
+	if (unpack_trees(nr, t, &opts))
+		return -1;
+
+	if (write_locked_index(r->index, &lock, COMMIT_LOCK))
+		return error(_("unable to write new index file"));
+
+	return 0;
+}
+
+static int write_tree(struct repository *r, struct tree **reference_tree)
+{
+	struct object_id oid;
+	int ret;
+
+	ret = write_index_as_tree(&oid, r->index, r->index_file, 0, NULL);
+	if (!ret)
+		*reference_tree = lookup_tree(r, &oid);
+
+	return ret;
+}
+
+int merge_strategies_octopus(struct repository *r,
+			     struct commit_list *bases, const char *head_arg,
+			     struct commit_list *remotes)
+{
+	int non_ff_merge = 0, ret = 0, references = 1;
+	struct commit **reference_commit;
+	struct tree *reference_tree;
+	struct commit_list *j;
+	struct object_id head;
+	struct strbuf sb = STRBUF_INIT;
+
+	get_oid(head_arg, &head);
+
+	reference_commit = xcalloc(commit_list_count(remotes) + 1, sizeof(struct commit *));
+	reference_commit[0] = lookup_commit_reference(r, &head);
+	reference_tree = repo_get_commit_tree(r, reference_commit[0]);
+
+	if (repo_index_has_changes(r, reference_tree, &sb)) {
+		error(_("Your local changes to the following files "
+			"would be overwritten by merge:\n  %s"),
+		      sb.buf);
+		strbuf_release(&sb);
+		ret = 2;
+		goto out;
+	}
+
+	for (j = remotes; j && j->item; j = j->next) {
+		struct commit *c = j->item;
+		struct object_id *oid = &c->object.oid;
+		struct commit_list *common, *k;
+		char *branch_name;
+		int can_ff = 1;
+
+		if (ret) {
+			/*
+			 * We allow only last one to have a
+			 * hand-resolvable conflicts.  Last round failed
+			 * and we still had a head to merge.
+			 */
+			puts(_("Automated merge did not work."));
+			puts(_("Should not be doing an octopus."));
+
+			ret = 2;
+			goto out;
+		}
+
+		branch_name = merge_get_better_branch_name(oid_to_hex(oid));
+		common = get_merge_bases_many(c, references, reference_commit);
+
+		if (!common)
+			die(_("Unable to find common commit with %s"), branch_name);
+
+		for (k = common; k && !oideq(&k->item->object.oid, oid); k = k->next);
+
+		if (k) {
+			printf(_("Already up to date with %s\n"), branch_name);
+			free(branch_name);
+			free_commit_list(common);
+			continue;
+		}
+
+		if (!non_ff_merge) {
+			int i;
+
+			for (i = 0, k = common; k && i < references && can_ff; k = k->next, i++) {
+				can_ff = oideq(&k->item->object.oid,
+					       &reference_commit[i]->object.oid);
+			}
+		}
+
+		if (!non_ff_merge && can_ff) {
+			/*
+			 * The first head being merged was a
+			 * fast-forward.  Advance the reference commit
+			 * to the head being merged, and use that tree
+			 * as the intermediate result of the merge.  We
+			 * still need to count this as part of the
+			 * parent set.
+			 */
+			struct object_id oids[2];
+			printf(_("Fast-forwarding to: %s\n"), branch_name);
+
+			oidcpy(oids, &head);
+			oidcpy(oids + 1, oid);
+
+			ret = fast_forward(r, oids, 2, 0);
+			if (ret) {
+				free(branch_name);
+				free_commit_list(common);
+				goto out;
+			}
+
+			references = 0;
+			write_tree(r, &reference_tree);
+		} else {
+			int i = 0;
+			struct tree *next = NULL;
+			struct object_id oids[MAX_UNPACK_TREES];
+
+			non_ff_merge = 1;
+			printf(_("Trying simple merge with %s\n"), branch_name);
+
+			for (k = common; k; k = k->next)
+				oidcpy(oids + (i++), &k->item->object.oid);
+
+			oidcpy(oids + (i++), &reference_tree->object.oid);
+			oidcpy(oids + (i++), oid);
+
+			if (fast_forward(r, oids, i, 1)) {
+				ret = 2;
+
+				free(branch_name);
+				free_commit_list(common);
+
+				goto out;
+			}
+
+			if (write_tree(r, &next)) {
+				struct lock_file lock = LOCK_INIT;
+
+				puts(_("Simple merge did not work, trying automatic merge."));
+				repo_hold_locked_index(r, &lock, LOCK_DIE_ON_ERROR);
+				ret = !!merge_all(r->index, 0, 0, merge_one_file_cb, r);
+				write_locked_index(r->index, &lock, COMMIT_LOCK);
+
+				write_tree(r, &next);
+			}
+
+			reference_tree = next;
+		}
+
+		reference_commit[references++] = c;
+
+		free(branch_name);
+		free_commit_list(common);
+	}
+
+out:
+	free(reference_commit);
+	return ret;
+}

merge-strategies.h

+#ifndef MERGE_STRATEGIES_H
+#define MERGE_STRATEGIES_H
+
+#include "commit.h"
+#include "object.h"
+
+int merge_strategies_one_file(struct repository *r,
+			      const struct object_id *orig_blob,
+			      const struct object_id *our_blob,
+			      const struct object_id *their_blob, const char *path,
+			      unsigned int orig_mode, unsigned int our_mode,
+			      unsigned int their_mode);
+
+typedef int (*merge_cb)(const struct object_id *orig_blob,
+			const struct object_id *our_blob,
+			const struct object_id *their_blob, const char *path,
+			unsigned int orig_mode, unsigned int our_mode, unsigned int their_mode,
+			void *data);
+
+int merge_one_file_cb(const struct object_id *orig_blob,
+		      const struct object_id *our_blob,
+		      const struct object_id *their_blob, const char *path,
+		      unsigned int orig_mode, unsigned int our_mode, unsigned int their_mode,
+		      void *data);
+
+int merge_program_cb(const struct object_id *orig_blob,
+		     const struct object_id *our_blob,
+		     const struct object_id *their_blob, const char *path,
+		     unsigned int orig_mode, unsigned int our_mode, unsigned int their_mode,
+		     void *data);
+
+int merge_one_path(struct index_state *istate, int oneshot, int quiet,
+		   const char *path, merge_cb cb, void *data);
+int merge_all(struct index_state *istate, int oneshot, int quiet,
+	      merge_cb cb, void *data);
+
+int merge_strategies_resolve(struct repository *r,
+			     struct commit_list *bases, const char *head_arg,
+			     struct commit_list *remote);
+int merge_strategies_octopus(struct repository *r,
+			     struct commit_list *bases, const char *head_arg,
+			     struct commit_list *remote);
+
+#endif /* MERGE_STRATEGIES_H */

merge.c

@@ -109,3 +109,15 @@ int checkout_fast_forward(struct repository *r,
 		return error(_("unable to write new index file"));
 	return 0;
 }
+
+char *merge_get_better_branch_name(const char *branch)
+{
+	static char githead_env[8 + GIT_MAX_HEXSZ + 1];
+	char *name;
+
+	if (strlen(branch) != the_hash_algo->hexsz)
+		return xstrdup(branch);
+	xsnprintf(githead_env, sizeof(githead_env), "GITHEAD_%s", branch);
+	name = getenv(githead_env);
+	return xstrdup(name ? name : branch);
+}

sequencer.c

@@ -33,6 +33,7 @@
 #include "commit-reach.h"
 #include "rebase-interactive.h"
 #include "reset.h"
+#include "merge-strategies.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
@@ -2008,9 +2009,18 @@ static int do_pick_commit(struct repository *r,
 
 		commit_list_insert(base, &common);
 		commit_list_insert(next, &remotes);
-		res |= try_merge_command(r, opts->strategy,
-					 opts->xopts_nr, (const char **)opts->xopts,
-					common, oid_to_hex(&head), remotes);
+
+		if (!strcmp(opts->strategy, "resolve")) {
+			repo_read_index(r);
+			res |= merge_strategies_resolve(r, common, oid_to_hex(&head), remotes);
+		} else if (!strcmp(opts->strategy, "octopus")) {
+			repo_read_index(r);
+			res |= merge_strategies_octopus(r, common, oid_to_hex(&head), remotes);
+		} else
+			res |= try_merge_command(r, opts->strategy,
+						 opts->xopts_nr, (const char **)opts->xopts,
+						 common, oid_to_hex(&head), remotes);
+
 		free_commit_list(common);
 		free_commit_list(remotes);
 	}

t/t6407-merge-binary.sh

@@ -5,7 +5,6 @@ test_description='ask merge-recursive to merge binary files'
 . ./test-lib.sh
 
 test_expect_success setup '
-
 	cat "$TEST_DIRECTORY"/test-binary-1.png >m &&
 	git add m &&
 	git ls-files -s | sed -e "s/ 0	/ 1	/" >E1 &&
@@ -35,33 +34,19 @@ test_expect_success setup '
 '
 
 test_expect_success resolve '
-
 	rm -f a* m* &&
 	git reset --hard anchor &&
-
-	if git merge -s resolve master
-	then
-		echo Oops, should not have succeeded
-		false
-	else
-		git ls-files -s >current
-		test_cmp expect current
-	fi
+	test_must_fail git merge -s resolve master &&
+	git ls-files -s >current &&
+	test_cmp expect current
 '
 
 test_expect_success recursive '
-
 	rm -f a* m* &&
 	git reset --hard anchor &&
-
-	if git merge -s recursive master
-	then
-		echo Oops, should not have succeeded
-		false
-	else
-		git ls-files -s >current
-		test_cmp expect current
-	fi
+	test_must_fail git merge -s recursive master &&
+	git ls-files -s >current &&
+	test_cmp expect current
 '
 
 test_done

t/t6415-merge-dir-to-symlink.sh

@@ -94,7 +94,7 @@ test_expect_success SYMLINKS 'a/b was resolved as symlink' '
 	test -h a/b
 '
 
-test_expect_failure 'do not lose untracked in merge (resolve)' '
+test_expect_success 'do not lose untracked in merge (resolve)' '
 	git reset --hard &&
 	git checkout baseline^0 &&
 	>a/b/c/e &&