From 83f386347f26336850e2efcd169d99e9ec89f027 Mon Sep 17 00:00:00 2001
From: ridiculousfish <corydoras@ridiculousfish.com>
Date: Mon, 6 Feb 2017 10:01:33 -0800
Subject: [PATCH] Make file_id_for_fd return kInvalidFiledID when passed a
 negative fd

Rather than making fstat do this, make it explicit.
---
 src/wutil.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/wutil.cpp b/src/wutil.cpp
index 10122453b..c989269cd 100644
--- a/src/wutil.cpp
+++ b/src/wutil.cpp
@@ -683,7 +683,7 @@ file_id_t file_id_t::file_id_from_stat(const struct stat *buf) {
 file_id_t file_id_for_fd(int fd) {
     file_id_t result = kInvalidFileID;
     struct stat buf = {};
-    if (0 == fstat(fd, &buf)) {
+    if (fd >= 0 && 0 == fstat(fd, &buf)) {
         result = file_id_t::file_id_from_stat(&buf);
     }
     return result;