1 file changed, 35 insertions, 8 deletions
diff --git a/source/ui-shared.c b/source/ui-shared.c
index 58e7f03..2f0843c 100644
--- a/source/ui-shared.c
+++ b/source/ui-shared.c
@@ -1741,20 +1741,47 @@ void cgit_print_filemode(unsigned short mode)
 	html_fileperm(mode);
 }
 
-static void compose_snapshot_prefix(struct strbuf *filename, const char *base, const char *ref)
+/*
+ * One tag's claim on a snapshot stem, the stem being the tag name with any
+ * leading v or V removed. Claims are counted over the tag list itself rather
+ * than by looking refs up by name, because a loose ref lookup on a
+ * case-insensitive filesystem finds v1.2 when asked for V1.2 and would call
+ * every tag still stored loose ambiguous.
+ */
+struct snapshot_stem {
+	const char *tag;
+	const char *stem;
+	int claimants;
+	int is_tag;
+};
+
+static int count_stem_claimants(const struct reference *ref, void *data)
 {
-	struct object_id oid;
+	struct snapshot_stem *probe = data;
+	const char *name = ref->name;
 
+	if (!strcmp(name, probe->tag))
+		probe->is_tag = 1;
+	if (name[0] == 'v' || name[0] == 'V')
+		name++;
+	if (!strcmp(name, probe->stem))
+		probe->claimants++;
+	return 0;
+}
+
+static void compose_snapshot_prefix(struct strbuf *filename, const char *base, const char *ref)
+{
 	// A tag named v1.2 or V1.2 gives its snapshot the prettier name 1.2,
 	// but only where dropping the letter cannot land two different tags on
 	// one name, so that a snapshot can still be traced back to the tag it
 	// was made from.
-	if (repo_get_oid(the_repository, cgit_fmt("refs/tags/%s", ref), &oid) == 0 &&
-	    (ref[0] == 'v' || ref[0] == 'V') && isdigit((unsigned char)ref[1]) &&
-	    ((repo_get_oid(the_repository, cgit_fmt("refs/tags/%s", ref + 1), &oid) == 0) +
-	     (repo_get_oid(the_repository, cgit_fmt("refs/tags/v%s", ref + 1), &oid) == 0) +
-	     (repo_get_oid(the_repository, cgit_fmt("refs/tags/V%s", ref + 1), &oid) == 0) == 1))
-		ref++;
+	if ((ref[0] == 'v' || ref[0] == 'V') && isdigit((unsigned char)ref[1])) {
+		struct snapshot_stem probe = { .tag = ref, .stem = ref + 1 };
+
+		refs_for_each_tag_ref(get_main_ref_store(the_repository), count_stem_claimants, &probe);
+		if (probe.is_tag && probe.claimants == 1)
+			ref++;
+	}
 
 	strbuf_addf(filename, "%s-%s", base, ref);
 }