Date: Thu, 24 Nov 2016 14:50:21 +0000 (UTC) From: =?UTF-8?Q?Dag-Erling_Sm=c3=b8rgrav?= <des@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r309109 - head/lib/libutil Message-ID: <201611241450.uAOEoLA5079215@repo.freebsd.org>
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Author: des Date: Thu Nov 24 14:50:21 2016 New Revision: 309109 URL: https://svnweb.freebsd.org/changeset/base/309109 Log: Add a warning against modifying this code without understanding it, and an example of how not to make it more portable. I've had this lying around uncommitted since 2009... Modified: head/lib/libutil/flopen.c Modified: head/lib/libutil/flopen.c ============================================================================== --- head/lib/libutil/flopen.c Thu Nov 24 14:48:46 2016 (r309108) +++ head/lib/libutil/flopen.c Thu Nov 24 14:50:21 2016 (r309109) @@ -1,5 +1,5 @@ /*- - * Copyright (c) 2007 Dag-Erling Coïdan Smørgrav + * Copyright (c) 2007-2009 Dag-Erling Coïdan Smørgrav * All rights reserved. * * Redistribution and use in source and binary forms, with or without @@ -37,6 +37,14 @@ __FBSDID("$FreeBSD$"); #include <libutil.h> +/* + * Reliably open and lock a file. + * + * DO NOT, UNDER PAIN OF DEATH, modify this code without first reading the + * revision history and discussing your changes with <des@freebsd.org>. + * Don't be fooled by the code's apparent simplicity; there would be no + * need for this function if it was as easy to get right as you think. + */ int flopen(const char *path, int flags, ...) { @@ -100,6 +108,14 @@ flopen(const char *path, int flags, ...) errno = serrno; return (-1); } +#ifdef DONT_EVEN_THINK_ABOUT_IT + if (fcntl(fd, F_SETFD, FD_CLOEXEC) != 0) { + serrno = errno; + (void)close(fd); + errno = serrno; + return (-1); + } +#endif return (fd); } }
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