[PATCH] libxl: save/restore errno in SIGCHLD handler

[PATCH] libxl: save/restore errno in SIGCHLD handler

[Ian Jackson]

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>
---
 tools/libxl/libxl_fork.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/libxl/libxl_fork.c b/tools/libxl/libxl_fork.c
index 044ddad..b6f0b2d 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)
-- 
1.7.10.4

Re: [PATCH] libxl: save/restore errno in SIGCHLD handler

[Ian Campbell]

On Mon, 2013-11-11 at 17:20 +0000, Ian Jackson wrote:
> 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>

> ---
>  tools/libxl/libxl_fork.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/libxl/libxl_fork.c b/tools/libxl/libxl_fork.c
> index 044ddad..b6f0b2d 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)

Re: [PATCH] libxl: save/restore errno in SIGCHLD handler

[Ian Jackson]

Ian Campbell writes ("Re: [PATCH] libxl: save/restore errno in SIGCHLD handler"):
> On Mon, 2013-11-11 at 17:20 +0000, Ian Jackson wrote:
> > 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>

Thanks, pushed.

Ian.

Re: [PATCH] libxl: save/restore errno in SIGCHLD handler

[Ian Jackson]

Ian Jackson writes ("Re: [PATCH] libxl: save/restore errno in SIGCHLD handler"):
> Ian Campbell writes ("Re: [PATCH] libxl: save/restore errno in SIGCHLD handler"):
> > On Mon, 2013-11-11 at 17:20 +0000, Ian Jackson wrote:
> > > 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>
> 
> Thanks, pushed.

Now applied to 4.3.  Was not applicable to 4.2, 4.1.

Ian.