update_walk: explicitly check for permission problems

Call access() and print an extra error message when EACCES is
returned.  Hopefully this will reduce the number of support requests
due to wrong file permissions.

1 files changed, 33 insertions, 0 deletions

diff --git a/src/update_walk.c b/src/update_walk.c
index a8e09793a..95d5854a8 100644
--- a/src/update_walk.c
+++ b/src/update_walk.c
@@ -546,6 +546,31 @@ update_container_file(	struct directory* directory,
 		return true;
 }
 
+/**
+ * Checks if the given permissions on the mapped file are given.
+ */
+static bool
+directory_child_access(const struct directory *directory,
+		       const char *name, int mode)
+{
+#ifdef WIN32
+	/* access() is useless on WIN32 */
+	(void)directory;
+	(void)name;
+	return true;
+#else
+	char *path = map_directory_child_fs(directory, name);
+	if (path == NULL)
+		/* something went wrong, but that isn't a permission
+		   problem */
+		return true;
+
+	bool success = access(path, mode) == 0 || errno != EACCES;
+	g_free(path);
+	return success;
+#endif
+}
+
 static void
 update_regular_file(struct directory *directory,
 		    const char *name, const struct stat *st)
@@ -562,6 +587,14 @@ update_regular_file(struct directory *directory,
 	{
 		struct song* song = songvec_find(&directory->songs, name);
 
+		if (!directory_child_access(directory, name, R_OK)) {
+			g_warning("no read permissions on %s/%s",
+				  directory_get_path(directory), name);
+			if (song != NULL)
+				delete_song(directory, song);
+			return;
+		}
+
 		if (!(song != NULL && st->st_mtime == song->mtime &&
 		      !walk_discard) &&
 			plugin->container_scan != NULL)