Re: [PATCH] qemu-nbd: Close inherited stderr

[Eric Blake <eblake@redhat.com>]

On 5/12/20 3:56 AM, Raphael Pour wrote:
> Hello,
> 
> after e6df58a5, the inherited stderr 'old_stderr' won't get closed
> anymore if 'fork_process' is false. This causes other processes relying
> on EOF to infinitely block or crash.
> 
>>From 47ab9b517038d13117876a8bb3ef45c53d7f2f9e Mon Sep 17 00:00:00 2001
> From: "Raphael Pour" <raphael.pour@hetzner.com>
> Date: Tue, 12 May 2020 10:18:44 +0200
> Subject: [PATCH] qemu-nbd: Close inherited stderr
> 
> Close inherited stderr of the parent if fork_process is false.
> Otherwise no one will close it. (introduced by e6df58a5)
> 
> Signed-off-by: Raphael Pour <raphael.pour@hetzner.com>
> ---
>   qemu-nbd.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 

Wouldn't it just be simpler to not dup in the first place?

diff --git i/qemu-nbd.c w/qemu-nbd.c
index 4aa005004ebd..6ba2544feb3a 100644
--- i/qemu-nbd.c
+++ w/qemu-nbd.c
@@ -916,7 +916,9 @@ int main(int argc, char **argv)
          } else if (pid == 0) {
              close(stderr_fd[0]);

-            old_stderr = dup(STDERR_FILENO);
+            if (fork_process) {
+                old_stderr = dup(STDERR_FILENO);
+            }
              ret = qemu_daemon(1, 0);

              /* Temporarily redirect stderr to the parent's pipe...  */


-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org