On Wed, 2016-02-17 at 10:39 +0000, Ian Campbell wrote:
> We assert that nullfd if not std{in,out,err} since that would result
> in closing one of the just dup2'd fds. For this to happen
> std{in,out,err} would have needed to be closed, at which point all
> sorts of other things could go wrong.
>
> CID: 1130519
>
> It was previously hypothesised[0] that fixing 1130516 would solve this
> too, but that appears to not have been the case.
>
> Compile tested only.
>
> [0] http://lists.xenproject.org/archives/html/xen-devel/2013-11/msg02931.
> html
>
> Signed-off-by: Ian Campbell <ian.campb...@citrix.com>
> Cc: andrew.coop...@citrix.com
ping?
> ---
> v2: Assert logfile and nullfd are not stdio fds
> ---
> tools/libxl/xl_cmdimpl.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
> index 9958d8a..a377de1 100644
> --- a/tools/libxl/xl_cmdimpl.c
> +++ b/tools/libxl/xl_cmdimpl.c
> @@ -499,12 +499,17 @@ static int do_daemonize(char *name, const char
> *pidfile)
>
> CHK_SYSCALL(logfile = open(fullname, O_WRONLY|O_CREAT|O_APPEND,
> 0644));
> free(fullname);
> + assert(logfile >= 3);
>
> CHK_SYSCALL(nullfd = open("/dev/null", O_RDONLY));
> + assert(nullfd >= 3);
> +
> dup2(nullfd, 0);
> dup2(logfile, 1);
> dup2(logfile, 2);
>
> + close(nullfd);
> +
> CHK_SYSCALL(daemon(0, 1));
>
> if (pidfile) {
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