From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Fri, 29 Mar 2024 14:14:55 +0000 (+0100)
Subject: FDWrapper: Do not try to close negative file descriptors
X-Git-Tag: rec-5.1.0-alpha1~67^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ef1e068d55f2247ff416204cebbbb96063a175c2;p=thirdparty%2Fpdns.git

FDWrapper: Do not try to close negative file descriptors

It turns out that some of the BPF helper functions return
a negative `errno` value in case of failure, and since we
wrap the return value into a `FDWrapper` right away this
led to a warning from Valgrind about trying to close an
invalid file descriptor.
---

diff --git a/pdns/misc.hh b/pdns/misc.hh
index 7798ada49b..61116f20ab 100644
--- a/pdns/misc.hh
+++ b/pdns/misc.hh
@@ -803,7 +803,7 @@ struct FDWrapper
 
   FDWrapper& operator=(FDWrapper&& rhs) noexcept
   {
-    if (d_fd != -1) {
+    if (d_fd >= 0) {
       close(d_fd);
     }
     d_fd = rhs.d_fd;
@@ -824,7 +824,7 @@ struct FDWrapper
   int reset()
   {
     int ret = 0;
-    if (d_fd != -1) {
+    if (d_fd >= 0) {
       ret = close(d_fd);
       d_fd = -1;
     }