Require a boundary in the about-path prefix check

The about subpath was confined to the readme directory with a plain
byte-prefix match, so a sibling directory sharing the base name as a
prefix passed the check and its files were served.

1 file changed, 7 insertions, 1 deletion

diff --git a/source/ui-summary.c b/source/ui-summary.c
index 471f0c9..a5f3ae8 100644
--- a/source/ui-summary.c
+++ b/source/ui-summary.c
@@ -86,7 +86,13 @@ static char* append_readme_path(const char *filename, const char *ref, const cha
 	if (!ref) {
 		resolved_base = realpath(base_dir, NULL);
 		resolved_full = realpath(full_path, NULL);
-		if (!resolved_base || !resolved_full || !starts_with(resolved_full, resolved_base)) {
+		/* Require a path-separator boundary after the base so a sibling
+		 * directory that merely shares the base as a name prefix (say
+		 * repo.git-backup next to repo.git) cannot pass the check. */
+		if (!resolved_base || !resolved_full ||
+		    !starts_with(resolved_full, resolved_base) ||
+		    (resolved_full[strlen(resolved_base)] != '\0' &&
+		     resolved_full[strlen(resolved_base)] != '/')) {
 			free(full_path);
 			full_path = NULL;
 		}