From owner-svn-src-head@FreeBSD.ORG  Tue Oct 15 13:32:02 2013
Return-Path: <owner-svn-src-head@FreeBSD.ORG>
Delivered-To: svn-src-head@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTP id 60162F8;
 Tue, 15 Oct 2013 13:32:02 +0000 (UTC)
 (envelope-from glebius@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org
 [IPv6:2001:1900:2254:2068::e6a:0])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (No client certificate requested)
 by mx1.freebsd.org (Postfix) with ESMTPS id 4DEB723D2;
 Tue, 15 Oct 2013 13:32:02 +0000 (UTC)
Received: from svn.freebsd.org ([127.0.1.70])
 by svn.freebsd.org (8.14.7/8.14.7) with ESMTP id r9FDW2m5027809;
 Tue, 15 Oct 2013 13:32:02 GMT (envelope-from glebius@svn.freebsd.org)
Received: (from glebius@localhost)
 by svn.freebsd.org (8.14.7/8.14.5/Submit) id r9FDW2NU027808;
 Tue, 15 Oct 2013 13:32:02 GMT (envelope-from glebius@svn.freebsd.org)
Message-Id: <201310151332.r9FDW2NU027808@svn.freebsd.org>
From: Gleb Smirnoff <glebius@FreeBSD.org>
Date: Tue, 15 Oct 2013 13:32:02 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: svn commit: r256537 - head/lib/libc/gen
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-BeenThere: svn-src-head@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: SVN commit messages for the src tree for head/-current
 <svn-src-head.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head>
List-Post: <mailto:svn-src-head@freebsd.org>
List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 15 Oct 2013 13:32:02 -0000

Author: glebius
Date: Tue Oct 15 13:32:01 2013
New Revision: 256537
URL: http://svnweb.freebsd.org/changeset/base/256537

Log:
    Make getutxent(3) more robust against bad utx.log files. Whenever we read
  zeroes, don't stop processing the file, but read until its end or valid
  data.
  
  In collaboration with:	ed

Modified:
  head/lib/libc/gen/getutxent.c

Modified: head/lib/libc/gen/getutxent.c
==============================================================================
--- head/lib/libc/gen/getutxent.c	Tue Oct 15 13:24:10 2013	(r256536)
+++ head/lib/libc/gen/getutxent.c	Tue Oct 15 13:32:01 2013	(r256537)
@@ -122,9 +122,20 @@ getfutxent(struct futx *fu)
 	if (udb == UTXDB_LOG) {
 		uint16_t len;
 
+retry:
 		if (fread(&len, sizeof(len), 1, uf) != 1)
 			return (-1);
 		len = be16toh(len);
+		if (len == 0) {
+			/*
+			 * XXX: Though zero-size records are valid in theory,
+			 * they can never occur in practice. Zero-size records
+			 * indicate file corruption. Seek one byte forward, to
+			 * see if we can find a record there.
+			 */
+			ungetc('\0', uf);
+			goto retry;
+		}
 		if (len > sizeof *fu) {
 			/* Forward compatibility. */
 			if (fread(fu, sizeof(*fu), 1, uf) != 1)