IABSD.fr/src/lib/libc/stdio/fopen.c

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• Author : deraadt
  Date : 2019-06-28 13:32:41
  Hash : df69c215
  Message : When system calls indicate an error they return -1, not some arbitrary value < 0. errno is only updated in this case. Change all (most?) callers of syscalls to follow this better, and let's see if this strictness helps us in the future.

• lib/libc/stdio/fopen.c

• /*	$OpenBSD: fopen.c,v 1.10 2019/06/28 13:32:42 deraadt Exp $ */
  /*-
   * Copyright (c) 1990, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * This code is derived from software contributed to Berkeley by
   * Chris Torek.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #include <limits.h>
  #include <stdio.h>
  #include <errno.h>
  #include <unistd.h>
  #include "local.h"
  
  FILE *
  fopen(const char *file, const char *mode)
  {
  	FILE *fp;
  	int f;
  	int flags, oflags;
  
  	if ((flags = __sflags(mode, &oflags)) == 0)
  		return (NULL);
  	if ((fp = __sfp()) == NULL)
  		return (NULL);
  	if ((f = open(file, oflags, DEFFILEMODE)) == -1) {
  		fp->_flags = 0;			/* release */
  		return (NULL);
  	}
  
  	/* _file is only a short */
  	if (f > SHRT_MAX) {
  		fp->_flags = 0;			/* release */
  		close(f);
  		errno = EMFILE;
  		return (NULL);
  	}
  
  	fp->_file = f;
  	fp->_flags = flags;
  	fp->_cookie = fp;
  	fp->_read = __sread;
  	fp->_write = __swrite;
  	fp->_seek = __sseek;
  	fp->_close = __sclose;
  
  	/*
  	 * When opening in append mode, even though we use O_APPEND,
  	 * we need to seek to the end so that ftell() gets the right
  	 * answer.  If the user then alters the seek pointer, or
  	 * the file extends, this will fail, but there is not much
  	 * we can do about this.  (We could set __SAPP and check in
  	 * fseek and ftell.)
  	 */
  	if (oflags & O_APPEND)
  		(void) __sseek(fp, 0, SEEK_END);
  	return (fp);
  }
  DEF_STRONG(fopen);