| Message ID | 20220609122701.17172-2-hreitz@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | qemu/qsd: Unlink absolute PID file path | expand |
On Thu, Jun 09, 2022 at 02:26:59PM +0200, Hanna Reitz wrote: > After writing the PID file, we register an atexit() handler to unlink it > when the process terminates. However, if the process has changed its > working directory in the meantime (e.g. in os_setup_post() when > daemonizing), this will not work when the PID file path was relative. > Therefore, pass the absolute path (created with realpath()) to the > unlink() call in the atexit() handler. > > (realpath() needs a path pointing to an existing file, so we cannot use > it before qemu_write_pidfile().) > > Reproducer: > $ cd /tmp > $ qemu-storage-daemon --daemonize --pidfile qsd.pid > $ file qsd.pid > qsd.pid: ASCII text > $ kill $(cat qsd.pid) > $ file qsd.pid > qsd.pid: ASCII text > > (qsd.pid should be gone after the process has terminated.) > > Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2092322 > Signed-off-by: Hanna Reitz <hreitz@redhat.com> > --- > storage-daemon/qemu-storage-daemon.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> With regards, Daniel
diff --git a/storage-daemon/qemu-storage-daemon.c b/storage-daemon/qemu-storage-daemon.c index c104817cdd..7b8d6cf381 100644 --- a/storage-daemon/qemu-storage-daemon.c +++ b/storage-daemon/qemu-storage-daemon.c @@ -61,6 +61,7 @@ #include "trace/control.h" static const char *pid_file; +static char *pid_file_realpath; static volatile bool exit_requested = false; void qemu_system_killed(int signal, pid_t pid) @@ -349,7 +350,7 @@ static void process_options(int argc, char *argv[], bool pre_init_pass) static void pid_file_cleanup(void) { - unlink(pid_file); + unlink(pid_file_realpath); } static void pid_file_init(void) @@ -365,6 +366,14 @@ static void pid_file_init(void) exit(EXIT_FAILURE); } + pid_file_realpath = g_malloc(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(EXIT_FAILURE); + } + atexit(pid_file_cleanup); }
After writing the PID file, we register an atexit() handler to unlink it when the process terminates. However, if the process has changed its working directory in the meantime (e.g. in os_setup_post() when daemonizing), this will not work when the PID file path was relative. Therefore, pass the absolute path (created with realpath()) to the unlink() call in the atexit() handler. (realpath() needs a path pointing to an existing file, so we cannot use it before qemu_write_pidfile().) Reproducer: $ cd /tmp $ qemu-storage-daemon --daemonize --pidfile qsd.pid $ file qsd.pid qsd.pid: ASCII text $ kill $(cat qsd.pid) $ file qsd.pid qsd.pid: ASCII text (qsd.pid should be gone after the process has terminated.) Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2092322 Signed-off-by: Hanna Reitz <hreitz@redhat.com> --- storage-daemon/qemu-storage-daemon.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)