| Message ID | 1446644927-8764-1-git-send-email-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
Paolo Bonzini <pbonzini@redhat.com> writes: > 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 <pbonzini@redhat.com> > --- > 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; Reviewed-by: Markus Armbruster <armbru@redhat.com>
On Wed, Nov 04, 2015 at 02:48:47PM +0100, Paolo Bonzini wrote: > 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 <pbonzini@redhat.com> Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com> > --- > 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 > >
04.11.2015 16:48, Paolo Bonzini wrote: > 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. Applied to -trivial, thanks! /mjt
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;
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 <pbonzini@redhat.com> --- util/qemu-sockets.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)