Re: [PATCH v2] vl: defuse PID file path resolve error

[Fiona Ebner <f.ebner@proxmox.com>]

Am 31.10.22 um 10:47 schrieb Fiona Ebner:
> Commit 85c4bf8aa6 ("vl: Unlink absolute PID file path") introduced a
> critical error when the PID file path cannot be resolved. Before this
> commit, it was possible to invoke QEMU when the PID file was a file
> created with mkstemp that was already unlinked at the time of the
> invocation. There might be other similar scenarios.
> 
> It should not be a critical error when the PID file unlink notifier
> can't be registered, because the path can't be resolved. If the file
> is already gone from QEMU's perspective, silently ignore the error.
> Otherwise, only print a warning.
> 
> Fixes: 85c4bf8aa6 ("vl: Unlink absolute PID file path")
> Reported-by: Dominik Csapak <d.csapak@proxmox.com>
> Suggested-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
> Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
> ---
> 
> v1 -> v2:
>     * Ignore error if errno == ENOENT.
> 
>  softmmu/vl.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index b464da25bc..cf2c591ba5 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -2432,10 +2432,11 @@ static void qemu_maybe_daemonize(const char *pid_file)
>  
>          pid_file_realpath = g_malloc0(PATH_MAX);
>          if (!realpath(pid_file, pid_file_realpath)) {
> -            error_report("cannot resolve PID file path: %s: %s",
> -                         pid_file, strerror(errno));
> -            unlink(pid_file);
> -            exit(1);
> +            if (errno != ENOENT) {
> +                warn_report("not removing PID file on exit: cannot resolve PID "
> +                            "file path: %s: %s", pid_file, strerror(errno));
> +            }
> +            return;
>          }
>  
>          qemu_unlink_pidfile_notifier = (struct UnlinkPidfileNotifier) {

Ping