stdio/FreeBSD/fopen.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)fopen.c     8.1 (Berkeley) 6/4/93";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/stdio/fopen.c,v 1.14 2008/04/22 17:03:32 jhb Exp $");
  38
  39 #include "namespace.h"
  40 #include <sys/types.h>
  41 #include <sys/stat.h>
  42 #include <fcntl.h>
  43 #include <unistd.h>
  44 #include <stdio.h>
  45 #include <errno.h>
  46 #include <limits.h>
  47 #include "un-namespace.h"
  48
  49 #include "local.h"
  50
  51 FILE *
  52 fopen(file, mode)
  53         const char * __restrict file;
  54         const char * __restrict mode;
  55 {
  56         FILE *fp;
  57         int f;
  58         int flags, oflags;
  59
  60         if ((flags = __sflags(mode, &oflags)) == 0)
  61                 return (NULL);
  62         if ((fp = __sfp()) == NULL)
  63                 return (NULL);
  64         if ((f = _open(file, oflags, DEFFILEMODE)) < 0) {
  65                 fp->_flags = 0;                 /* release */
  66                 return (NULL);
  67         }
  68         /*
  69          * File descriptors are a full int, but _file is only a short.
  70          * If we get a valid file descriptor that is greater than
  71          * SHRT_MAX, then the fd will get sign-extended into an
  72          * invalid file descriptor.  Handle this case by failing the
  73          * open.
  74          */
  75         if (f > SHRT_MAX) {
  76                 fp->_flags = 0;                 /* release */
  77                 _close(f);
  78                 errno = EMFILE;
  79                 return (NULL);
  80         }
  81         fp->_file = f;
  82         fp->_flags = flags;
  83         fp->_cookie = fp;
  84         fp->_read = __sread;
  85         fp->_write = __swrite;
  86         fp->_seek = __sseek;
  87         fp->_close = __sclose;
  88         /*
  89          * When opening in append mode, even though we use O_APPEND,
  90          * we need to seek to the end so that ftell() gets the right
  91          * answer.  If the user then alters the seek pointer, or
  92          * the file extends, this will fail, but there is not much
  93          * we can do about this.  (We could set __SAPP and check in
  94          * fseek and ftell.)
  95          */
  96         if (oflags & O_APPEND)
  97                 (void)_sseek(fp, (fpos_t)0, SEEK_END);
  98         return (fp);
  99 }