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      1 /*	$OpenBSD: fdopen.c,v 1.5 2005/08/08 08:05:36 espie Exp $ */
      2 /*-
      3  * Copyright (c) 1990, 1993
      4  *	The Regents of the University of California.  All rights reserved.
      5  *
      6  * This code is derived from software contributed to Berkeley by
      7  * Chris Torek.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #include <sys/types.h>
     35 #include <fcntl.h>
     36 #include <unistd.h>
     37 #include <stdio.h>
     38 #include <errno.h>
     39 #include "local.h"
     40 
     41 FILE *
     42 fdopen(int fd, const char *mode)
     43 {
     44 	FILE *fp;
     45 	int flags, oflags, fdflags, tmp;
     46 
     47 	if ((flags = __sflags(mode, &oflags)) == 0)
     48 		return (NULL);
     49 
     50 	/* Make sure the mode the user wants is a subset of the actual mode. */
     51 	if ((fdflags = fcntl(fd, F_GETFL, 0)) < 0)
     52 		return (NULL);
     53 	tmp = fdflags & O_ACCMODE;
     54 	if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
     55 		errno = EINVAL;
     56 		return (NULL);
     57 	}
     58 
     59 	if ((fp = __sfp()) == NULL)
     60 		return (NULL);
     61 	fp->_flags = flags;
     62 	/*
     63 	 * If opened for appending, but underlying descriptor does not have
     64 	 * O_APPEND bit set, assert __SAPP so that __swrite() will lseek to
     65 	 * end before each write.
     66 	 */
     67 	if ((oflags & O_APPEND) && !(fdflags & O_APPEND))
     68 		fp->_flags |= __SAPP;
     69 	fp->_file = fd;
     70 	fp->_cookie = fp;
     71 	fp->_read = __sread;
     72 	fp->_write = __swrite;
     73 	fp->_seek = __sseek;
     74 	fp->_close = __sclose;
     75 	return (fp);
     76 }
     77