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Tue, 25 Aug 2020 15:36:29 +0000 (UTC) Date: Tue, 25 Aug 2020 16:36:27 +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: <20200825153627.GA107278@redhat.com> References: <20200821172105.608752-1-berrange@redhat.com> <20200821172105.608752-4-berrange@redhat.com> <87wo1mbvw2.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <87wo1mbvw2.fsf@dusky.pond.sub.org> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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=205.139.110.61; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/25 01:35:36 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=-0.958, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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 , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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. > > > errno = EINVAL; > > return -1; > > } > > @@ -336,6 +343,16 @@ qemu_open_internal(const char *name, int flags, mode_t mode) > > } > > #endif /* ! O_CLOEXEC */ > > > > + if (ret == -1) { > > + const char *action = "open"; > > + if (flags & O_CREAT) { > > + action = "create"; > > + } > > + error_setg_errno(errp, errno, "Could not %s '%s' flags 0x%x", > > + action, name, flags); > > Not a good user experience: > > Could not open '/etc/shadow' flags 0x0: Permission denied > > Better: > > Could not open '/etc/shadow' for reading: Permission denied > > Are you sure flags other than the access mode (O_RDONLY, O_WRONLY, > O_RDWR) must be included in the error message? It was the flags other than access mode that I was thinking were more important to log. I'm ambivalent htough, so can drop the flags if it is thought to be overkill. > > If you must report flags in hexadecimal, then please reporting them more > consistently. Right now you have > > for %s flags 0x%x > '%s' flags %x > > Perhaps '%s' with flags 0x%x > > > + } > > + > > + > > return ret; > > } > > > > @@ -352,7 +369,7 @@ int qemu_open_old(const char *name, int flags, ...) > > } > > va_end(ap); > > > > - ret = qemu_open_internal(name, flags, mode); > > + ret = qemu_open_internal(name, flags, mode, NULL); > > > > #ifdef O_DIRECT > > if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) { > > 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 :|