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Tue, 25 Aug 2020 17:16:12 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Subject: Re: [PATCH v4 4/6] util: introduce qemu_open and qemu_create with error reporting References: <20200821172105.608752-1-berrange@redhat.com> <20200821172105.608752-5-berrange@redhat.com> Date: Tue, 25 Aug 2020 17:16:12 +0200 In-Reply-To: <20200821172105.608752-5-berrange@redhat.com> ("Daniel P. =?utf-8?Q?Berrang=C3=A9=22's?= message of "Fri, 21 Aug 2020 18:21:03 +0100") Message-ID: <87sgcabvsz.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/25 02:03:58 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_H5=0.001, RCVD_IN_MSPIKE_WL=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: , Cc: Kevin Wolf , Max Reitz , qemu-devel@nongnu.org, qemu-block@nongnu.org, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Daniel P. Berrang=C3=A9 writes: > qemu_open_old() works like open(): set errno and return -1 on failure. > It has even more failure modes, though. Reporting the error clearly > to users is basically impossible for many of them. > > Our standard cure for "errno is too coarse" is the Error object. > Introduce two new helper methods: > > int qemu_open(const char *name, int flags, Error **errp); > int qemu_create(const char *name, int flags, mode_t mode, Error **errp)= ; > > Note that with this design we no longer require or even accept the > O_CREAT flag. Avoiding overloading the two distinct operations > means we can avoid variable arguments which would prevent 'errp' from > being the last argument. It also gives us a guarantee that the 'mode' is > given when creating files, avoiding a latent security bug. > > Signed-off-by: Daniel P. Berrang=C3=A9 > --- > include/qemu/osdep.h | 6 ++++++ > util/osdep.c | 21 +++++++++++++++++---- > 2 files changed, 23 insertions(+), 4 deletions(-) > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > index 18333e9006..13a821845b 100644 > --- a/include/qemu/osdep.h > +++ b/include/qemu/osdep.h > @@ -497,7 +497,13 @@ int qemu_madvise(void *addr, size_t len, int advice)= ; > int qemu_mprotect_rwx(void *addr, size_t size); > int qemu_mprotect_none(void *addr, size_t size); > =20 > +/* > + * Don't introduce new usage of this function, prefer the following > + * qemu_open/qemu_create that take an "Error **errp" > + */ > int qemu_open_old(const char *name, int flags, ...); > +int qemu_open(const char *name, int flags, Error **errp); > +int qemu_create(const char *name, int flags, mode_t mode, Error **errp); > int qemu_close(int fd); > int qemu_unlink(const char *name); > #ifndef _WIN32 > diff --git a/util/osdep.c b/util/osdep.c > index 9c7118d3cb..a4956fbf6b 100644 > --- a/util/osdep.c > +++ b/util/osdep.c > @@ -344,10 +344,7 @@ qemu_open_internal(const char *name, int flags, mode= _t mode, Error **errp) > #endif /* ! O_CLOEXEC */ > =20 > if (ret =3D=3D -1) { > - const char *action =3D "open"; > - if (flags & O_CREAT) { > - action =3D "create"; > - } > + const char *action =3D flags & O_CREAT ? "create" : "open"; > error_setg_errno(errp, errno, "Could not %s '%s' flags 0x%x", > action, name, flags); > } Squash this hunk into PATCH 3, please. > @@ -357,6 +354,22 @@ qemu_open_internal(const char *name, int flags, mode= _t mode, Error **errp) > } > =20 > =20 > +int qemu_open(const char *name, int flags, Error **errp) > +{ > + assert(!(flags & O_CREAT)); > + > + return qemu_open_internal(name, flags, 0, errp); > +} > + > + > +int qemu_create(const char *name, int flags, mode_t mode, Error **errp) > +{ > + assert(!(flags & O_CREAT)); > + > + return qemu_open_internal(name, flags | O_CREAT, mode, errp); > +} > + > + > int qemu_open_old(const char *name, int flags, ...) > { > va_list ap; Other than that: Reviewed-by: Markus Armbruster