Move try_merge_command and checkout_fast_forward to libgit.a

These functions are called in sequencer.c, which is part of
libgit.a. This makes libgit.a potentially require builtin/merge.c for
external git commands.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>

6 files changed, 125 insertions, 112 deletions

diff --git a/Makefile b/Makefile
index 40829a9e99..0877f4091d 100644
--- a/Makefile
+++ b/Makefile
@@ -763,6 +763,7 @@ LIB_OBJS += lockfile.o
 LIB_OBJS += log-tree.o
 LIB_OBJS += mailmap.o
 LIB_OBJS += match-trees.o
+LIB_OBJS += merge.o
 LIB_OBJS += merge-file.o
 LIB_OBJS += merge-recursive.o
 LIB_OBJS += mergesort.o
diff --git a/builtin/merge.c b/builtin/merge.c
index 0ec8f0d449..a96e8eac19 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -628,59 +628,6 @@ static void write_tree_trivial(unsigned char *sha1)
 		die(_("git write-tree failed to write a tree"));
 }
 
-static const char *merge_argument(struct commit *commit)
-{
-	if (commit)
-		return sha1_to_hex(commit->object.sha1);
-	else
-		return EMPTY_TREE_SHA1_HEX;
-}
-
-int try_merge_command(const char *strategy, size_t xopts_nr,
-		      const char **xopts, struct commit_list *common,
-		      const char *head_arg, struct commit_list *remotes)
-{
-	const char **args;
-	int i = 0, x = 0, ret;
-	struct commit_list *j;
-	struct strbuf buf = STRBUF_INIT;
-
-	args = xmalloc((4 + xopts_nr + commit_list_count(common) +
-			commit_list_count(remotes)) * 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(merge_argument(j->item));
-	args[i++] = "--";
-	args[i++] = head_arg;
-	for (j = remotes; j; j = j->next)
-		args[i++] = xstrdup(merge_argument(j->item));
-	args[i] = NULL;
-	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;
-	for (j = remotes; j; j = j->next)
-		free((void *)args[i++]);
-	free(args);
-	discard_cache();
-	if (read_cache() < 0)
-		die(_("failed to read the cache"));
-	resolve_undo_clear();
-
-	return ret;
-}
-
 static int try_merge_strategy(const char *strategy, struct commit_list *common,
 			      struct commit_list *remoteheads,
 			      struct commit *head, const char *head_arg)
@@ -762,56 +709,6 @@ static int count_unmerged_entries(void)
 	return ret;
 }
 
-int checkout_fast_forward(const unsigned char *head, const unsigned char *remote)
-{
-	struct tree *trees[MAX_UNPACK_TREES];
-	struct unpack_trees_options opts;
-	struct tree_desc t[MAX_UNPACK_TREES];
-	int i, fd, nr_trees = 0;
-	struct dir_struct dir;
-	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
-
-	refresh_cache(REFRESH_QUIET);
-
-	fd = hold_locked_index(lock_file, 1);
-
-	memset(&trees, 0, sizeof(trees));
-	memset(&opts, 0, sizeof(opts));
-	memset(&t, 0, sizeof(t));
-	if (overwrite_ignore) {
-		memset(&dir, 0, sizeof(dir));
-		dir.flags |= DIR_SHOW_IGNORED;
-		setup_standard_excludes(&dir);
-		opts.dir = &dir;
-	}
-
-	opts.head_idx = 1;
-	opts.src_index = &the_index;
-	opts.dst_index = &the_index;
-	opts.update = 1;
-	opts.verbose_update = 1;
-	opts.merge = 1;
-	opts.fn = twoway_merge;
-	setup_unpack_trees_porcelain(&opts, "merge");
-
-	trees[nr_trees] = parse_tree_indirect(head);
-	if (!trees[nr_trees++])
-		return -1;
-	trees[nr_trees] = parse_tree_indirect(remote);
-	if (!trees[nr_trees++])
-		return -1;
-	for (i = 0; i < nr_trees; i++) {
-		parse_tree(trees[i]);
-		init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
-	}
-	if (unpack_trees(nr_trees, t, &opts))
-		return -1;
-	if (write_cache(fd, active_cache, active_nr) ||
-		commit_locked_index(lock_file))
-		die(_("unable to write new index file"));
-	return 0;
-}
-
 static void split_merge_strategies(const char *string, struct strategy **list,
 				   int *nr, int *alloc)
 {
@@ -1424,7 +1321,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		}
 
 		if (checkout_fast_forward(head_commit->object.sha1,
-					  commit->object.sha1)) {
+					  commit->object.sha1,
+					  overwrite_ignore)) {
 			ret = 1;
 			goto done;
 		}
diff --git a/cache.h b/cache.h
index a58df84bd3..2dc4decbc9 100644
--- a/cache.h
+++ b/cache.h
@@ -1265,8 +1265,15 @@ struct startup_info {
 };
 extern struct startup_info *startup_info;
 
-/* builtin/merge.c */
-int checkout_fast_forward(const unsigned char *from, const unsigned char *to);
+/* merge.c */
+struct commit_list;
+int try_merge_command(const char *strategy, size_t xopts_nr,
+		const char **xopts, struct commit_list *common,
+		const char *head_arg, struct commit_list *remotes);
+int checkout_fast_forward(const unsigned char *from,
+			  const unsigned char *to,
+			  int overwrite_ignore);
+
 
 int sane_execvp(const char *file, char *const argv[]);
 
diff --git a/merge-recursive.h b/merge-recursive.h
index 58f3435e9e..9e090a3470 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -59,9 +59,4 @@ struct tree *write_tree_from_memory(struct merge_options *o);
 
 int parse_merge_opt(struct merge_options *out, const char *s);
 
-/* builtin/merge.c */
-int try_merge_command(const char *strategy, size_t xopts_nr,
-		const char **xopts, struct commit_list *common,
-		const char *head_arg, struct commit_list *remotes);
-
 #endif
diff --git a/merge.c b/merge.c
new file mode 100644
index 0000000000..70f1000fcb
--- /dev/null
+++ b/merge.c
@@ -0,0 +1,112 @@
+#include "cache.h"
+#include "commit.h"
+#include "run-command.h"
+#include "resolve-undo.h"
+#include "tree-walk.h"
+#include "unpack-trees.h"
+#include "dir.h"
+
+static const char *merge_argument(struct commit *commit)
+{
+	if (commit)
+		return sha1_to_hex(commit->object.sha1);
+	else
+		return EMPTY_TREE_SHA1_HEX;
+}
+
+int try_merge_command(const char *strategy, size_t xopts_nr,
+		      const char **xopts, struct commit_list *common,
+		      const char *head_arg, struct commit_list *remotes)
+{
+	const char **args;
+	int i = 0, x = 0, ret;
+	struct commit_list *j;
+	struct strbuf buf = STRBUF_INIT;
+
+	args = xmalloc((4 + xopts_nr + commit_list_count(common) +
+			commit_list_count(remotes)) * 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(merge_argument(j->item));
+	args[i++] = "--";
+	args[i++] = head_arg;
+	for (j = remotes; j; j = j->next)
+		args[i++] = xstrdup(merge_argument(j->item));
+	args[i] = NULL;
+	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;
+	for (j = remotes; j; j = j->next)
+		free((void *)args[i++]);
+	free(args);
+	discard_cache();
+	if (read_cache() < 0)
+		die(_("failed to read the cache"));
+	resolve_undo_clear();
+
+	return ret;
+}
+
+int checkout_fast_forward(const unsigned char *head,
+			  const unsigned char *remote,
+			  int overwrite_ignore)
+{
+	struct tree *trees[MAX_UNPACK_TREES];
+	struct unpack_trees_options opts;
+	struct tree_desc t[MAX_UNPACK_TREES];
+	int i, fd, nr_trees = 0;
+	struct dir_struct dir;
+	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+
+	refresh_cache(REFRESH_QUIET);
+
+	fd = hold_locked_index(lock_file, 1);
+
+	memset(&trees, 0, sizeof(trees));
+	memset(&opts, 0, sizeof(opts));
+	memset(&t, 0, sizeof(t));
+	if (overwrite_ignore) {
+		memset(&dir, 0, sizeof(dir));
+		dir.flags |= DIR_SHOW_IGNORED;
+		setup_standard_excludes(&dir);
+		opts.dir = &dir;
+	}
+
+	opts.head_idx = 1;
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
+	opts.update = 1;
+	opts.verbose_update = 1;
+	opts.merge = 1;
+	opts.fn = twoway_merge;
+	setup_unpack_trees_porcelain(&opts, "merge");
+
+	trees[nr_trees] = parse_tree_indirect(head);
+	if (!trees[nr_trees++])
+		return -1;
+	trees[nr_trees] = parse_tree_indirect(remote);
+	if (!trees[nr_trees++])
+		return -1;
+	for (i = 0; i < nr_trees; i++) {
+		parse_tree(trees[i]);
+		init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
+	}
+	if (unpack_trees(nr_trees, t, &opts))
+		return -1;
+	if (write_cache(fd, active_cache, active_nr) ||
+		commit_locked_index(lock_file))
+		die(_("unable to write new index file"));
+	return 0;
+}
diff --git a/sequencer.c b/sequencer.c
index e3723d2095..be0cb8b107 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -191,7 +191,7 @@ static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 	struct ref_lock *ref_lock;
 
 	read_cache();
-	if (checkout_fast_forward(from, to))
+	if (checkout_fast_forward(from, to, 1))
 		exit(1); /* the callee should have complained already */
 	ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 	return write_ref_sha1(ref_lock, to, "cherry-pick");