From: Ian Jackson <ian.jackson@eu.citrix.com>
Date: Mon, 11 Nov 2013 17:17:55 +0000 (+0000)
Subject: libxl: save/restore errno in SIGCHLD handler
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~5983
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=704d10289bcaee46a3ef6cdc7966186e3b8033fa;p=xen.git

libxl: save/restore errno in SIGCHLD handler

Without this, code interrupted by SIGCHLD may experience strange
values of errno.  (As far as I know this is not the cause of any
reported bugs.)

This fix should be backported in due course.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---

diff --git a/tools/libxl/libxl_fork.c b/tools/libxl/libxl_fork.c
index 044ddad139..b6f0b2d034 100644
--- a/tools/libxl/libxl_fork.c
+++ b/tools/libxl/libxl_fork.c
@@ -157,8 +157,10 @@ int libxl__carefd_fd(const libxl__carefd *cf)
 
 static void sigchld_handler(int signo)
 {
+    int esave = errno;
     int e = libxl__self_pipe_wakeup(sigchld_owner->sigchld_selfpipe[1]);
     assert(!e); /* errors are probably EBADF, very bad */
+    errno = esave;
 }
 
 static void sigchld_removehandler_core(void)