From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/5927 Path: news.gmane.org!not-for-mail From: Szabolcs Nagy Newsgroups: gmane.linux.lib.musl.general Subject: fgets behaviour after eof Date: Wed, 27 Aug 2014 13:16:20 +0200 Message-ID: <20140827111620.GY22308@port70.net> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1409138201 4511 80.91.229.3 (27 Aug 2014 11:16:41 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 27 Aug 2014 11:16:41 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-5934-gllmg-musl=m.gmane.org@lists.openwall.com Wed Aug 27 13:16:35 2014 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1XMbDO-0001h0-54 for gllmg-musl@plane.gmane.org; Wed, 27 Aug 2014 13:16:34 +0200 Original-Received: (qmail 14013 invoked by uid 550); 27 Aug 2014 11:16:33 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 14005 invoked from network); 27 Aug 2014 11:16:32 -0000 Mail-Followup-To: musl@lists.openwall.com Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Xref: news.gmane.org gmane.linux.lib.musl.general:5927 Archived-At: the C standard requires that "If end-of-file is encountered and no characters have been read into the array, the contents of the array remain unchanged and a null pointer is returned. If a read error occurs during the operation, the array contents are indeterminate and a null pointer is returned." but musl's fgets always terminates the buffer with \0 even after EOF, this is easy to fix: - *p = 0; + if (s) *p = 0; However the behaviour of fgets(s, 1, f) is unclear if feof(f) is true, in this case nothing is read so fgets cannot "encounter" end-of-file, so it may set s[0]=0 and return s or it could check feof and return 0. (glibc does not check feof)