1 files changed, 53 insertions, 14 deletions

diff --git a/shallow.c b/shallow.c
index a0363dea20..8a9c96d019 100644
--- a/shallow.c
+++ b/shallow.c
@@ -3,6 +3,16 @@
 #include "tag.h"
 
 static int is_shallow = -1;
+static struct stat shallow_stat;
+static char *alternate_shallow_file;
+
+void set_alternate_shallow_file(const char *path)
+{
+	if (is_shallow != -1)
+		die("BUG: is_repository_shallow must not be called before set_alternate_shallow_file");
+	free(alternate_shallow_file);
+	alternate_shallow_file = path ? xstrdup(path) : NULL;
+}
 
 int register_shallow(const unsigned char *sha1)
 {
@@ -21,12 +31,21 @@ int is_repository_shallow(void)
 {
 	FILE *fp;
 	char buf[1024];
+	const char *path = alternate_shallow_file;
 
 	if (is_shallow >= 0)
 		return is_shallow;
 
-	fp = fopen(git_path("shallow"), "r");
-	if (!fp) {
+	if (!path)
+		path = git_path("shallow");
+	/*
+	 * fetch-pack sets '--shallow-file ""' as an indicator that no
+	 * shallow file should be used. We could just open it and it
+	 * will likely fail. But let's do an explicit check instead.
+	 */
+	if (!*path ||
+	    stat(path, &shallow_stat) ||
+	    (fp = fopen(path, "r")) == NULL) {
 		is_shallow = 0;
 		return is_shallow;
 	}
@@ -72,8 +91,14 @@ struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
 		}
 		if (parse_commit(commit))
 			die("invalid commit");
-		commit->object.flags |= not_shallow_flag;
 		cur_depth++;
+		if (cur_depth >= depth) {
+			commit_list_insert(commit, &result);
+			commit->object.flags |= shallow_flag;
+			commit = NULL;
+			continue;
+		}
+		commit->object.flags |= not_shallow_flag;
 		for (p = commit->parents, commit = NULL; p; p = p->next) {
 			if (!p->item->util) {
 				int *pointer = xmalloc(sizeof(int));
@@ -85,20 +110,34 @@ struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
 					continue;
 				*pointer = cur_depth;
 			}
-			if (cur_depth < depth) {
-				if (p->next)
-					add_object_array(&p->item->object,
-							NULL, &stack);
-				else {
-					commit = p->item;
-					cur_depth = *(int *)commit->util;
-				}
-			} else {
-				commit_list_insert(p->item, &result);
-				p->item->object.flags |= shallow_flag;
+			if (p->next)
+				add_object_array(&p->item->object,
+						NULL, &stack);
+			else {
+				commit = p->item;
+				cur_depth = *(int *)commit->util;
 			}
 		}
 	}
 
 	return result;
 }
+
+void check_shallow_file_for_update(void)
+{
+	struct stat st;
+
+	if (!is_shallow)
+		return;
+	else if (is_shallow == -1)
+		die("BUG: shallow must be initialized by now");
+
+	if (stat(git_path("shallow"), &st))
+		die("shallow file was removed during fetch");
+	else if (st.st_mtime != shallow_stat.st_mtime
+#ifdef USE_NSEC
+		 || ST_MTIME_NSEC(st) != ST_MTIME_NSEC(shallow_stat)
+#endif
+		   )
+		die("shallow file was changed during fetch");
+}