[pve-devel] [PATCH v3 qemu] init: daemonize: defuse PID file resolve error

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

When proxmox-file-restore invokes QEMU, the PID file is a (temporary)
file that's already unlinked, so resolving the absolute path here
failed.

It should not be a critical error when the PID file unlink handler
can't be registered, because the path can't be resolved for whatever
reason. If the file is already gone from QEMU's perspective (i.e.
errno is ENOENT), silently ignore the error. Otherwise, print a
warning.

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>
---

Changes from v2:
    * Be quiet when error is ENOENT.

 softmmu/vl.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/softmmu/vl.c b/softmmu/vl.c
index 0d233d55f3..f71421f80a 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -2445,10 +2445,11 @@ 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) {
-- 
2.30.2