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dmarc=none (p=none dis=none) header.from=cs.ucla.edu Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=eggert@cs.ucla.edu Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 5F88A1600E0; Fri, 22 May 2020 20:06:35 -0700 (PDT) Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id M4ZFGUOa_k-u; Fri, 22 May 2020 20:06:34 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id AB8BC1600E1; Fri, 22 May 2020 20:06:34 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id KzJNzHu44maT; Fri, 22 May 2020 20:06:34 -0700 (PDT) Received: from [192.168.1.9] (cpe-23-242-74-103.socal.res.rr.com [23.242.74.103]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 769851600E0; Fri, 22 May 2020 20:06:34 -0700 (PDT) Subject: Re: RFC: *scanf vs. overflow To: Rich Felker , Eric Blake References: <20200523011614.GE1079@brightrain.aerifal.cx> From: Paul Eggert Autocrypt: addr=eggert@cs.ucla.edu; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200523011614.GE1079@brightrain.aerifal.cx> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Florian Weimer , glibc list , "libguestfs@redhat.com" Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" On 5/22/20 6:16 PM, Rich Felker wrote: > A new feature > will not reliably be usable for decades in portable software, but new > documentation of existing universal practice would be immediately > usable. We could do both. Also, we could change glibc's behavior in a simpler way, by not adding a new flag; but if an integer is out of range, then scan only the initial prefix that fits, leaving the trailing digits for the rest of the format to scan. This also conforms to POSIX and is more likely to cause C programs to do the right thing (i.e., report a failure) than the current behavior does. And with luck perhaps we could eventually get POSIX to standardize this behavior.