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emacs 28.3 From: Petr Machata To: David Ahern CC: Petr Machata , Jiri Pirko , , , Subject: Re: [patch iproute2-next v3 3/6] devlink: extend pr_out_nested_handle() to print object Date: Mon, 30 Oct 2023 12:03:57 +0100 In-Reply-To: Message-ID: <871qdc5mcj.fsf@nvidia.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.126.230.35] X-ClientProxiedBy: rnnvmail202.nvidia.com (10.129.68.7) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS3PEPF000099DB:EE_|IA0PR12MB8301:EE_ X-MS-Office365-Filtering-Correlation-Id: 9f13e0c3-f46f-409e-f5e6-08dbd9434495 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230031)(4636009)(39860400002)(396003)(136003)(376002)(346002)(230922051799003)(64100799003)(451199024)(1800799009)(186009)(82310400011)(36840700001)(40470700004)(46966006)(2906002)(86362001)(41300700001)(4326008)(8676002)(8936002)(5660300002)(40460700003)(36756003)(478600001)(40480700001)(47076005)(6666004)(53546011)(7636003)(6916009)(54906003)(316002)(16526019)(26005)(70206006)(426003)(70586007)(336012)(36860700001)(83380400001)(82740400003)(2616005)(356005);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Oct 2023 12:25:13.8365 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9f13e0c3-f46f-409e-f5e6-08dbd9434495 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DS3PEPF000099DB.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR12MB8301 David Ahern writes: > On 10/27/23 7:12 AM, Petr Machata wrote: >> I was wondering whether somehing like this might make sense in the >> iproute2 library: >> >> #define alloca_sprintf(FMT, ...) ({ \ >> int xasprintf_n = snprintf(NULL, 0, (FMT), __VA_ARGS__); \ >> char *xasprintf_buf = alloca(xasprintf_n); \ >> sprintf(xasprintf_buf, (FMT), __VA_ARGS__); \ >> xasprintf_buf; \ >> }) >> >> void foo() { >> const char *buf = alloca_sprintf("%x %y %z", etc.); >> printf(... buf ...); >> } >> >> I'm not really happy with it -- because of alloca vs. array, and because >> of the double evaluation. But all those SPRINT_BUF's peppered everywhere >> make me uneasy every time I read or write them. > > agreed. > >> >> Or maybe roll something custom asprintf-like that can reuse and/or >> realloc a passed-in buffer? >> >> The sprintf story is pretty bad in iproute2 right now, IMHO. > > It is a bit of a mess. If you have a few cycles, want to send an RFC? > Just pick 1 or 2 to convert to show intent with a new design. I picked at it a bit over the weekend, but came up with nothing that I find comfortable proposing. The static buffer approach has some major advantages: nothing ever fails and nothing ever needs cleanups. This keeps the client code tidy and compact. Anything dynamic adds points of failure and cleanups, which in C means more client-side boilerplate. Anyway, I'll pick at it some more and see I find anything.