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([2001:b07:6468:f312:1868:42dd:216c:2c09]) by smtp.gmail.com with ESMTPSA id m8sm7943142wmc.28.2020.04.02.11.57.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 02 Apr 2020 11:57:28 -0700 (PDT) Subject: Re: Questionable aspects of QEMU Error's design To: Markus Armbruster , Peter Maydell References: <87o8sblgto.fsf@dusky.pond.sub.org> <87sghmbfgc.fsf@dusky.pond.sub.org> <44b5ff2c-6dce-e516-a9cc-9d80354c5a72@virtuozzo.com> <877dyy9shs.fsf@dusky.pond.sub.org> From: Paolo Bonzini Message-ID: Date: Thu, 2 Apr 2020 20:57:28 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <877dyy9shs.fsf@dusky.pond.sub.org> Content-Language: en-US X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 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: Vladimir Sementsov-Ogievskiy , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 02/04/20 10:55, Markus Armbruster wrote: > > When you return non-null/null or true/false on success/error, neglecting > to document that in a function contract can perhaps be tolerated; you're > using the return type the common, obvious way. But when you return 0/-1 > or 0/-errno, please spell it out. I've seen too many "Operation not > permitted" that were actually -1 mistaken for -EPERM. Hopefully that would be avoided by the usage of Error itself. Paolo > Also too many > functions that return -1 for some failures and -errno for others.