Handle buffer underflow as an internal error.

mdboom · mdboom · commit 7be497edbaee · 2015-03-16T11:59:59.000-04:00
diff --git a/src/_path.h b/src/_path.h
@@ -959,7 +959,11 @@ char *__append_to_string(char *p, char **buffer, size_t *buffersize,
     int buffersize_int = (int)*buffersize;
 
     for (const char *i = content; *i; ++i) {
-        if (p < *buffer || p - *buffer >= buffersize_int) {
+        if (p < *buffer) {
+            /* This is just an internal error */
+            return NULL;
+        }
+        if (p - *buffer >= buffersize_int) {
             int diff = p - *buffer;
             *buffersize *= 2;
             *buffer = (char *)realloc(*buffer, *buffersize);
