From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/13759 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: Bug in gets function? Date: Mon, 11 Feb 2019 22:48:38 -0500 Message-ID: <20190212034838.GH23599@brightrain.aerifal.cx> References: Reply-To: musl@lists.openwall.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="75605"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Mutt/1.5.21 (2010-09-15) To: musl@lists.openwall.com Original-X-From: musl-return-13775-gllmg-musl=m.gmane.org@lists.openwall.com Tue Feb 12 04:48:54 2019 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.89) (envelope-from ) id 1gtP41-000JaV-Ol for gllmg-musl@m.gmane.org; Tue, 12 Feb 2019 04:48:53 +0100 Original-Received: (qmail 21617 invoked by uid 550); 12 Feb 2019 03:48:51 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 21599 invoked from network); 12 Feb 2019 03:48:51 -0000 Content-Disposition: inline In-Reply-To: Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:13759 Archived-At: On Mon, Feb 11, 2019 at 06:55:24PM -0800, Keyhan Vakil wrote: > Hi. It seems that the gets function does not follow the C99 spec. In > particular, if the input contains a null byte in the middle of the > input, then the new-line character is not discarded. > > For reference, here's the relevant part in the C99 standard > (7.19.7.7): > > > The gets function reads characters from the input stream pointed to > > by stdin, into the array pointed to by s, until end-of-file is > > encountered or a new-line character is read. Any new-line character > > is discarded, and a null character is written immediately after the > > last character read into the array. > > Here is an example: > > #include > char s[8]; > int main() { > gets(s); > for (int i = 0; i < sizeof s; i++) { > printf("%02x ", s[i]); > } > printf("\n"); > return 0; > } > > When compiled against gcc: > > $ echo -e 'A\x00B' | ./a.out > 41 00 42 00 00 00 00 00 > > When compiled against musl: > > $ echo -e 'A\x00B' | ./a.out > 41 00 42 0a 00 00 00 00 > > Note the terminating newline, which contradicts the spec. I think this bug report is correct; however the gets function is awful, removed in C11, and should never be used. :-) I will see what can be done to fix it though. Rich