+
+/* Returns the directory name portion of 'file_name' as a malloc()'d string,
+ * similar to the POSIX dirname() function but thread-safe. */
+char *
+dir_name(const char *file_name)
+{
+ size_t len = strlen(file_name);
+ while (len > 0 && file_name[len - 1] == '/') {
+ len--;
+ }
+ while (len > 0 && file_name[len - 1] != '/') {
+ len--;
+ }
+ while (len > 0 && file_name[len - 1] == '/') {
+ len--;
+ }
+ if (!len) {
+ return xstrdup((file_name[0] == '/'
+ && file_name[1] == '/'
+ && file_name[2] != '/') ? "//"
+ : file_name[0] == '/' ? "/"
+ : ".");
+ } else {
+ return xmemdup0(file_name, len);
+ }
+}