commit-reach(get_octopus_merge_bases): pass on "missing commits" errors

The `merge_bases_many()` function was just taught to indicate parsing
errors, and now the `repo_get_merge_bases()` function (which is also
surfaced via the `get_merge_bases()` macro) is aware of that, too.

Naturally, the callers need to be adjusted now, too.

Next step: adjust `repo_get_merge_bases_many()`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/merge-base.c

@@ -74,13 +74,17 @@ static int handle_independent(int count, const char **args)
 static int handle_octopus(int count, const char **args, int show_all)
 {
 	struct commit_list *revs = NULL;
-	struct commit_list *result, *rev;
+	struct commit_list *result = NULL, *rev;
 	int i;
 
 	for (i = count - 1; i >= 0; i--)
 		commit_list_insert(get_commit_reference(args[i]), &revs);
 
-	result = get_octopus_merge_bases(revs);
+	if (get_octopus_merge_bases(revs, &result) < 0) {
+		free_commit_list(revs);
+		free_commit_list(result);
+		return 128;
+	}
 	free_commit_list(revs);
 	reduce_heads_replace(&result);
 

builtin/merge.c

@@ -1523,7 +1523,11 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	} else {
 		struct commit_list *list = remoteheads;
 		commit_list_insert(head_commit, &list);
-		common = get_octopus_merge_bases(list);
+		if (get_octopus_merge_bases(list, &common) < 0) {
+			free(list);
+			ret = 2;
+			goto done;
+		}
 		free(list);
 	}
 

builtin/pull.c

@@ -815,7 +815,7 @@ static int get_octopus_merge_base(struct object_id *merge_base,
 		const struct object_id *merge_head,
 		const struct object_id *fork_point)
 {
-	struct commit_list *revs = NULL, *result;
+	struct commit_list *revs = NULL, *result = NULL;
 
 	commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 			   &revs);
@@ -825,7 +825,8 @@ static int get_octopus_merge_base(struct object_id *merge_base,
 		commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 				   &revs);
 
-	result = get_octopus_merge_bases(revs);
+	if (get_octopus_merge_bases(revs, &result) < 0)
+		exit(128);
 	free_commit_list(revs);
 	reduce_heads_replace(&result);
 

commit-reach.c

@@ -175,24 +175,26 @@ static int merge_bases_many(struct repository *r,
 	return 0;
 }
 
-struct commit_list *get_octopus_merge_bases(struct commit_list *in)
+int get_octopus_merge_bases(struct commit_list *in, struct commit_list **result)
 {
-	struct commit_list *i, *j, *k, *ret = NULL;
+	struct commit_list *i, *j, *k;
 
 	if (!in)
-		return ret;
+		return 0;
 
-	commit_list_insert(in->item, &ret);
+	commit_list_insert(in->item, result);
 
 	for (i = in->next; i; i = i->next) {
 		struct commit_list *new_commits = NULL, *end = NULL;
 
-		for (j = ret; j; j = j->next) {
+		for (j = *result; j; j = j->next) {
 			struct commit_list *bases = NULL;
 			if (repo_get_merge_bases(the_repository, i->item,
 						 j->item, &bases) < 0) {
 				free_commit_list(bases);
-				return NULL;
+				free_commit_list(*result);
+				*result = NULL;
+				return -1;
 			}
 			if (!new_commits)
 				new_commits = bases;
@@ -201,10 +203,10 @@ struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 			for (k = bases; k; k = k->next)
 				end = k;
 		}
-		free_commit_list(ret);
-		ret = new_commits;
+		free_commit_list(*result);
+		*result = new_commits;
 	}
-	return ret;
+	return 0;
 }
 
 static int remove_redundant_no_gen(struct repository *r,

commit-reach.h

@@ -21,7 +21,7 @@ struct commit_list *repo_get_merge_bases_many_dirty(struct repository *r,
 						    struct commit *one, int n,
 						    struct commit **twos);
 
-struct commit_list *get_octopus_merge_bases(struct commit_list *in);
+int get_octopus_merge_bases(struct commit_list *in, struct commit_list **result);
 
 int repo_is_descendant_of(struct repository *r,
 			  struct commit *commit,