1 files changed, 85 insertions, 49 deletions

diff --git a/builtin/merge.c b/builtin/merge.c
index 30264cfd7c..4a4c09496c 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -14,6 +14,7 @@
 #include "run-command.h"
 #include "diff.h"
 #include "refs.h"
+#include "refspec.h"
 #include "commit.h"
 #include "diffcore.h"
 #include "revision.h"
@@ -33,6 +34,8 @@
 #include "sequencer.h"
 #include "string-list.h"
 #include "packfile.h"
+#include "tag.h"
+#include "alias.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)
@@ -212,9 +215,9 @@ static struct option builtin_merge_options[] = {
 	OPT_BOOL('e', "edit", &option_edit,
 		N_("edit message before committing")),
 	OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
-	{ OPTION_SET_INT, 0, "ff-only", &fast_forward, NULL,
-		N_("abort if fast-forward is not possible"),
-		PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, FF_ONLY },
+	OPT_SET_INT_F(0, "ff-only", &fast_forward,
+		      N_("abort if fast-forward is not possible"),
+		      FF_ONLY, PARSE_OPT_NONEG),
 	OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 	OPT_BOOL(0, "verify-signatures", &verify_signatures,
 		N_("verify that the named commit has a valid GPG signature")),
@@ -279,7 +282,7 @@ out:
 	return rc;
 }
 
-static void read_empty(unsigned const char *sha1, int verbose)
+static void read_empty(const struct object_id *oid, int verbose)
 {
 	int i = 0;
 	const char *args[7];
@@ -289,15 +292,15 @@ static void read_empty(unsigned const char *sha1, int verbose)
 		args[i++] = "-v";
 	args[i++] = "-m";
 	args[i++] = "-u";
-	args[i++] = EMPTY_TREE_SHA1_HEX;
-	args[i++] = sha1_to_hex(sha1);
+	args[i++] = empty_tree_oid_hex();
+	args[i++] = oid_to_hex(oid);
 	args[i] = NULL;
 
 	if (run_command_v_opt(args, RUN_GIT_CMD))
 		die(_("read-tree failed"));
 }
 
-static void reset_hard(unsigned const char *sha1, int verbose)
+static void reset_hard(const struct object_id *oid, int verbose)
 {
 	int i = 0;
 	const char *args[6];
@@ -307,7 +310,7 @@ static void reset_hard(unsigned const char *sha1, int verbose)
 		args[i++] = "-v";
 	args[i++] = "--reset";
 	args[i++] = "-u";
-	args[i++] = sha1_to_hex(sha1);
+	args[i++] = oid_to_hex(oid);
 	args[i] = NULL;
 
 	if (run_command_v_opt(args, RUN_GIT_CMD))
@@ -323,7 +326,7 @@ static void restore_state(const struct object_id *head,
 	if (is_null_oid(stash))
 		return;
 
-	reset_hard(head->hash, 1);
+	reset_hard(head, 1);
 
 	args[2] = oid_to_hex(stash);
 
@@ -411,7 +414,7 @@ static void finish(struct commit *head_commit,
 			 * We ignore errors in 'gc --auto', since the
 			 * user should see them.
 			 */
-			close_all_packs();
+			close_all_packs(the_repository->objects);
 			run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 		}
 	}
@@ -442,6 +445,7 @@ static void merge_name(const char *remote, struct strbuf *msg)
 	struct object_id branch_head;
 	struct strbuf buf = STRBUF_INIT;
 	struct strbuf bname = STRBUF_INIT;
+	struct merge_remote_desc *desc;
 	const char *ptr;
 	char *found_ref;
 	int len, early;
@@ -514,16 +518,13 @@ static void merge_name(const char *remote, struct strbuf *msg)
 		strbuf_release(&truname);
 	}
 
-	if (remote_head->util) {
-		struct merge_remote_desc *desc;
-		desc = merge_remote_util(remote_head);
-		if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
-			strbuf_addf(msg, "%s\t\t%s '%s'\n",
-				    oid_to_hex(&desc->obj->oid),
-				    typename(desc->obj->type),
-				    remote);
-			goto cleanup;
-		}
+	desc = merge_remote_util(remote_head);
+	if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
+		strbuf_addf(msg, "%s\t\t%s '%s'\n",
+			    oid_to_hex(&desc->obj->oid),
+			    type_name(desc->obj->type),
+			    remote);
+		goto cleanup;
 	}
 
 	strbuf_addf(msg, "%s\t\tcommit '%s'\n",
@@ -638,7 +639,7 @@ static int read_tree_trivial(struct object_id *common, struct object_id *head,
 
 static void write_tree_trivial(struct object_id *oid)
 {
-	if (write_cache_as_tree(oid->hash, 0, NULL))
+	if (write_cache_as_tree(oid, 0, NULL))
 		die(_("git write-tree failed to write a tree"));
 }
 
@@ -646,15 +647,14 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 			      struct commit_list *remoteheads,
 			      struct commit *head)
 {
-	static struct lock_file lock;
+	struct lock_file lock = LOCK_INIT;
 	const char *head_arg = "HEAD";
 
 	hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 	refresh_cache(REFRESH_QUIET);
-	if (active_cache_changed &&
-	    write_locked_index(&the_index, &lock, COMMIT_LOCK))
+	if (write_locked_index(&the_index, &lock,
+			       COMMIT_LOCK | SKIP_IF_UNCHANGED))
 		return error(_("Unable to write index."));
-	rollback_lock_file(&lock);
 
 	if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 		int clean, x;
@@ -691,10 +691,9 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 				remoteheads->item, reversed, &result);
 		if (clean < 0)
 			exit(128);
-		if (active_cache_changed &&
-		    write_locked_index(&the_index, &lock, COMMIT_LOCK))
+		if (write_locked_index(&the_index, &lock,
+				       COMMIT_LOCK | SKIP_IF_UNCHANGED))
 			die (_("unable to write %s"), get_index_file());
-		rollback_lock_file(&lock);
 		return clean ? 0 : 1;
 	} else {
 		return try_merge_command(strategy, xopts_nr, xopts,
@@ -806,22 +805,21 @@ static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 {
 	struct object_id result_tree, result_commit;
 	struct commit_list *parents, **pptr = &parents;
-	static struct lock_file lock;
+	struct lock_file lock = LOCK_INIT;
 
 	hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
 	refresh_cache(REFRESH_QUIET);
-	if (active_cache_changed &&
-	    write_locked_index(&the_index, &lock, COMMIT_LOCK))
+	if (write_locked_index(&the_index, &lock,
+			       COMMIT_LOCK | SKIP_IF_UNCHANGED))
 		return error(_("Unable to write index."));
-	rollback_lock_file(&lock);
 
 	write_tree_trivial(&result_tree);
 	printf(_("Wonderful.\n"));
 	pptr = commit_list_append(head, pptr);
 	pptr = commit_list_append(remoteheads->item, pptr);
 	prepare_to_commit(remoteheads);
-	if (commit_tree(merge_msg.buf, merge_msg.len, result_tree.hash, parents,
-			result_commit.hash, NULL, sign_commit))
+	if (commit_tree(merge_msg.buf, merge_msg.len, &result_tree, parents,
+			&result_commit, NULL, sign_commit))
 		die(_("failed to write commit object"));
 	finish(head, remoteheads, &result_commit, "In-index merge");
 	drop_save();
@@ -845,8 +843,8 @@ static int finish_automerge(struct commit *head,
 		commit_list_insert(head, &parents);
 	strbuf_addch(&merge_msg, '\n');
 	prepare_to_commit(remoteheads);
-	if (commit_tree(merge_msg.buf, merge_msg.len, result_tree->hash, parents,
-			result_commit.hash, NULL, sign_commit))
+	if (commit_tree(merge_msg.buf, merge_msg.len, result_tree, parents,
+			&result_commit, NULL, sign_commit))
 		die(_("failed to write commit object"));
 	strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
 	finish(head, remoteheads, &result_commit, buf.buf);
@@ -934,8 +932,11 @@ static void write_merge_heads(struct commit_list *remoteheads)
 	for (j = remoteheads; j; j = j->next) {
 		struct object_id *oid;
 		struct commit *c = j->item;
-		if (c->util && merge_remote_util(c)->obj) {
-			oid = &merge_remote_util(c)->obj->oid;
+		struct merge_remote_desc *desc;
+
+		desc = merge_remote_util(c);
+		if (desc && desc->obj) {
+			oid = &desc->obj->oid;
 		} else {
 			oid = &c->object.oid;
 		}
@@ -1125,6 +1126,43 @@ static struct commit_list *collect_parents(struct commit *head_commit,
 	return remoteheads;
 }
 
+static int merging_a_throwaway_tag(struct commit *commit)
+{
+	char *tag_ref;
+	struct object_id oid;
+	int is_throwaway_tag = 0;
+
+	/* Are we merging a tag? */
+	if (!merge_remote_util(commit) ||
+	    !merge_remote_util(commit)->obj ||
+	    merge_remote_util(commit)->obj->type != OBJ_TAG)
+		return is_throwaway_tag;
+
+	/*
+	 * Now we know we are merging a tag object.  Are we downstream
+	 * and following the tags from upstream?  If so, we must have
+	 * the tag object pointed at by "refs/tags/$T" where $T is the
+	 * tagname recorded in the tag object.  We want to allow such
+	 * a "just to catch up" merge to fast-forward.
+	 *
+	 * Otherwise, we are playing an integrator's role, making a
+	 * merge with a throw-away tag from a contributor with
+	 * something like "git pull $contributor $signed_tag".
+	 * We want to forbid such a merge from fast-forwarding
+	 * by default; otherwise we would not keep the signature
+	 * anywhere.
+	 */
+	tag_ref = xstrfmt("refs/tags/%s",
+			  ((struct tag *)merge_remote_util(commit)->obj)->tag);
+	if (!read_ref(tag_ref, &oid) &&
+	    !oidcmp(&oid, &merge_remote_util(commit)->obj->oid))
+		is_throwaway_tag = 0;
+	else
+		is_throwaway_tag = 1;
+	free(tag_ref);
+	return is_throwaway_tag;
+}
+
 int cmd_merge(int argc, const char **argv, const char *prefix)
 {
 	struct object_id result_tree, stash, head_oid;
@@ -1148,14 +1186,15 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	branch = branch_to_free = resolve_refdup("HEAD", 0, &head_oid, NULL);
 	if (branch)
 		skip_prefix(branch, "refs/heads/", &branch);
+
+	init_diff_ui_defaults();
+	git_config(git_merge_config, NULL);
+
 	if (!branch || is_null_oid(&head_oid))
 		head_commit = NULL;
 	else
 		head_commit = lookup_commit_or_die(&head_oid, "HEAD");
 
-	init_diff_ui_defaults();
-	git_config(git_merge_config, NULL);
-
 	if (branch_mergeoptions)
 		parse_branch_merge_options(branch_mergeoptions);
 	argc = parse_options(argc, argv, prefix, builtin_merge_options,
@@ -1262,7 +1301,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		if (remoteheads->next)
 			die(_("Can merge only exactly one commit into empty head"));
 		remote_head_oid = &remoteheads->item->object.oid;
-		read_empty(remote_head_oid->hash, 0);
+		read_empty(remote_head_oid, 0);
 		update_ref("initial pull", "HEAD", remote_head_oid, NULL, 0,
 			   UPDATE_REFS_DIE_ON_ERR);
 		goto done;
@@ -1289,7 +1328,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 
 			check_commit_signature(commit, &signature_check);
 
-			find_unique_abbrev_r(hex, commit->object.oid.hash, DEFAULT_ABBREV);
+			find_unique_abbrev_r(hex, &commit->object.oid, DEFAULT_ABBREV);
 			switch (signature_check.result) {
 			case 'G':
 				break;
@@ -1322,10 +1361,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			    oid_to_hex(&commit->object.oid));
 		setenv(buf.buf, merge_remote_util(commit)->name, 1);
 		strbuf_reset(&buf);
-		if (fast_forward != FF_ONLY &&
-		    merge_remote_util(commit) &&
-		    merge_remote_util(commit)->obj &&
-		    merge_remote_util(commit)->obj->type == OBJ_TAG)
+		if (fast_forward != FF_ONLY && merging_a_throwaway_tag(commit))
 			fast_forward = FF_NO;
 	}
 
@@ -1385,9 +1421,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 
 		if (verbosity >= 0) {
 			printf(_("Updating %s..%s\n"),
-			       find_unique_abbrev(head_commit->object.oid.hash,
+			       find_unique_abbrev(&head_commit->object.oid,
 						  DEFAULT_ABBREV),
-			       find_unique_abbrev(remoteheads->item->object.oid.hash,
+			       find_unique_abbrev(&remoteheads->item->object.oid,
 						  DEFAULT_ABBREV));
 		}
 		strbuf_addstr(&msg, "Fast-forward");