From: Pavel Rochnyack <pavel2000@ngs.ru>
Date: Mon, 31 Jul 2017 05:21:24 +0000 (+0700)
Subject: Proper return value from 'swrite()' when connection has been closed
X-Git-Tag: collectd-5.8.0~76^2
X-Git-Url: https://git.octo.it/?p=collectd.git;a=commitdiff_plain;h=243163d9a20ed9961f6c2eefe59b411b5c39d707;ds=sidebyside

Proper return value from 'swrite()' when connection has been closed

According to POSIX, errno is set only if 'recv()' returns -1.
When connection has been closed, 'recv()' returns 0 and errno left untouched.
For functions which check errno value after 'swrite()', errno now is set to ECONNRESET,
so they produce correct message 'Connection reset by peer'.
---

diff --git a/src/daemon/common.c b/src/daemon/common.c
index 3ae61d85..6c856a6b 100644
--- a/src/daemon/common.c
+++ b/src/daemon/common.c
@@ -269,7 +269,8 @@ ssize_t swrite(int fd, const void *buf, size_t count) {
     if (recv(fd, buffer, sizeof(buffer), MSG_PEEK | MSG_DONTWAIT) == 0) {
       /* if recv returns zero (even though poll() said there is data to be
        * read), that means the connection has been closed */
-      return errno ? errno : -1;
+      errno = ECONNRESET;
+      return -1;
     }
   }