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Mon, 22 Jun 2020 17:38:52 +0000 (UTC) Date: Mon, 22 Jun 2020 18:38:49 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Michal Privoznik Subject: Re: [PATCH v2 1/2] util: Introduce qemu_get_host_name() Message-ID: <20200622173849.GN736373@redhat.com> References: <567f969602c1742e23c7760944e909346b2d012b.1592846572.git.mprivozn@redhat.com> MIME-Version: 1.0 In-Reply-To: <567f969602c1742e23c7760944e909346b2d012b.1592846572.git.mprivozn@redhat.com> User-Agent: Mutt/1.14.0 (2020-05-02) 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 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 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 = 2020/06/22 03:17:49 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=-1, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: vfeenstr@redhat.com, sw@weilnetz.de, mdroth@linux.vnet.ibm.com, qemu-devel@nongnu.org, marcandre.lureau@gmail.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Jun 22, 2020 at 07:26:44PM +0200, Michal Privoznik wrote: > This function offers operating system agnostic way to fetch host > name. It is implemented for both POSIX-like and Windows systems. > > Signed-off-by: Michal Privoznik > --- > include/qemu/osdep.h | 10 ++++++++++ > util/oslib-posix.c | 32 ++++++++++++++++++++++++++++++++ > util/oslib-win32.c | 13 +++++++++++++ > 3 files changed, 55 insertions(+) > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > index ff7c17b857..a795d46b28 100644 > --- a/include/qemu/osdep.h > +++ b/include/qemu/osdep.h > @@ -607,4 +607,14 @@ static inline void qemu_reset_optind(void) > #endif > } > > +/** > + * qemu_get_host_name: > + * @errp: Error object > + * > + * Operating system agnostic way of querying host name. > + * > + * Returns allocated hostname (caller should free), NULL on failure. > + */ > +char *qemu_get_host_name(Error **errp); > + > #endif > diff --git a/util/oslib-posix.c b/util/oslib-posix.c > index 916f1be224..865a3d71a7 100644 > --- a/util/oslib-posix.c > +++ b/util/oslib-posix.c > @@ -761,3 +761,35 @@ void sigaction_invoke(struct sigaction *action, > } > action->sa_sigaction(info->ssi_signo, &si, NULL); > } > + > +#ifndef HOST_NAME_MAX > +# ifdef _POSIX_HOST_NAME_MAX > +# define HOST_NAME_MAX _POSIX_HOST_NAME_MAX > +# else > +# define HOST_NAME_MAX 255 > +# endif > +#endif > + > +char *qemu_get_host_name(Error **errp) > +{ > + long len = -1; > + char *hostname; > + > +#ifdef _SC_HOST_NAME_MAX > + len = sysconf(_SC_HOST_NAME_MAX); > +#endif /* _SC_HOST_NAME_MAX */ > + > + if (len < 0) { > + len = HOST_NAME_MAX; > + } > + > + hostname = g_malloc0(len + 1); Nitpick, generally qemu prefers g_new0 > + > + if (gethostname(hostname, len) < 0) { > + error_setg_errno(errp, errno, > + "cannot get hostname"); > + return NULL; > + } According to my man page, it is undefined by POSIX whether there's a trailing NUL when hostname exceeds the buffer, so the paranoid thing todo is to add hostname[len] = '\0'; 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 :|