Only allow absolute paths

ulib/string/string.c

@@ -282,3 +282,34 @@ void * string_memmove(void* dest, const void* src, unsigned int n)
     }
     return dest;
 }
+
+char *string_strstr(const char *str, const char *substring)
+{
+    const char *a;
+    const char *b;
+
+    b = substring;
+
+    if (*b == 0) {
+        return (char *) str;
+    }
+
+    for ( ; *str != 0; str += 1) {
+        if (*str != *b) {
+            continue;
+        }
+
+        a = str;
+        while (1) {
+            if (*b == 0) {
+                return (char *) str;
+            }
+            if (*a++ != *b++) {
+                break;
+            }
+        }
+        b = substring;
+    }
+
+    return NULL;
+}