From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52253) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtyQn-0007z0-P0 for qemu-devel@nongnu.org; Wed, 04 Nov 2015 08:48:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZtyQl-0002Pq-2v for qemu-devel@nongnu.org; Wed, 04 Nov 2015 08:48:53 -0500 From: Paolo Bonzini Date: Wed, 4 Nov 2015 14:48:47 +0100 Message-Id: <1446644927-8764-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH v2] qemu-sockets: do not test path with access() before unlinking List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-trivial@nongnu.org, armbru@redhat.com, crobinso@redhat.com Using access() is a time-of-check/time-of-use race condition. It is okay to use them to provide better error messages, but that is pretty much it. This is not one such case; on the other hand, access() *will* skip unlink() for a non-existent path, so ignore ENOENT return values from the unlink() system call. Signed-off-by: Paolo Bonzini --- util/qemu-sockets.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c index 9142917..de9145a 100644 --- a/util/qemu-sockets.c +++ b/util/qemu-sockets.c @@ -751,8 +751,7 @@ int unix_listen_opts(QemuOpts *opts, Error **errp) qemu_opt_set(opts, "path", un.sun_path, &error_abort); } - if ((access(un.sun_path, F_OK) == 0) && - unlink(un.sun_path) < 0) { + if (unlink(un.sun_path) < 0 && errno != ENOENT) { error_setg_errno(errp, errno, "Failed to unlink socket %s", un.sun_path); goto err; -- 2.5.0