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Thu, 27 Aug 2020 13:28:00 +0000 (UTC) Date: Thu, 27 Aug 2020 14:27:57 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Subject: Re: [PATCH v4 3/6] util: add Error object for qemu_open_internal error reporting Message-ID: <20200827132757.GU192458@redhat.com> References: <20200821172105.608752-1-berrange@redhat.com> <20200821172105.608752-4-berrange@redhat.com> <87wo1mbvw2.fsf@dusky.pond.sub.org> <20200825153627.GA107278@redhat.com> <87k0xl7jpk.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <87k0xl7jpk.fsf@dusky.pond.sub.org> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.120; envelope-from=berrange@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/27 00:13:19 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.959, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Kevin Wolf , qemu-devel@nongnu.org, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Aug 26, 2020 at 01:03:19PM +0200, Markus Armbruster wrote: > Daniel P. Berrangé writes: > > > On Tue, Aug 25, 2020 at 05:14:21PM +0200, Markus Armbruster wrote: > >> Daniel P. Berrangé writes: > >> > >> > Instead of relying on the limited information from errno, we can now > >> > also provide detailed error messages. > >> > >> The more detailed error messages are currently always ignored, but the > >> next patches will fix that. > >> > >> > Signed-off-by: Daniel P. Berrangé > >> > --- > >> > util/osdep.c | 21 +++++++++++++++++++-- > >> > 1 file changed, 19 insertions(+), 2 deletions(-) > >> > > >> > diff --git a/util/osdep.c b/util/osdep.c > >> > index 9ff92551e7..9c7118d3cb 100644 > >> > --- a/util/osdep.c > >> > +++ b/util/osdep.c > >> > @@ -284,7 +284,7 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive) > >> > * Opens a file with FD_CLOEXEC set > >> > */ > >> > static int > >> > -qemu_open_internal(const char *name, int flags, mode_t mode) > >> > +qemu_open_internal(const char *name, int flags, mode_t mode, Error **errp) > >> > { > >> > int ret; > >> > > >> > @@ -298,24 +298,31 @@ qemu_open_internal(const char *name, int flags, mode_t mode) > >> > > >> > fdset_id = qemu_parse_fdset(fdset_id_str); > >> > if (fdset_id == -1) { > >> > + error_setg(errp, "Could not parse fdset %s", name); > >> > errno = EINVAL; > >> > return -1; > >> > } > >> > > >> > fd = monitor_fdset_get_fd(fdset_id, flags); > >> > if (fd < 0) { > >> > + error_setg_errno(errp, -fd, "Could not acquire FD for %s flags %x", > >> > + name, flags); > >> > errno = -fd; > >> > return -1; > >> > } > >> > > >> > dupfd = qemu_dup_flags(fd, flags); > >> > if (dupfd == -1) { > >> > + error_setg_errno(errp, errno, "Could not dup FD for %s flags %x", > >> > + name, flags); > >> > return -1; > >> > } > >> > > >> > ret = monitor_fdset_dup_fd_add(fdset_id, dupfd); > >> > if (ret == -1) { > >> > close(dupfd); > >> > + error_setg(errp, "Could not save FD for %s flags %x", > >> > + name, flags); > >> > >> Can this happen? > > > > Well there's code in monitor_fdset_dup_fd_add that can return -1. > > It fails when > > * @fdset_id contains @dupfd > > @dupfd is a fresh file descriptor. If @fdset_id already contains it, > it's stale there. That would be a programming error. Recommend to > assert. > > * @fdset_id is not in @mon_fdsets > > monitor_fdset_get_fd() fails the same way. monitor_fdset_dup_fd_add() > can fail that way after monitor_fdset_get_fd() succeed only if the fd > set went away between the two. Could that happen? Would it be safe? > > This is the only user of monitor_fdset_dup_fd_add(). Why not remove > the awkward failure mode by making monitor_fdset_dup_fd_add() dup the > fd and add? Once we push the qemu_dup call into monitor_fdset_dup_fd_add, we might as well go the whole way and merge monitor_fdset_get_fd into it too. So I've done that, turning 3 calls into 1. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|