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 #ifdef VARIANT_DARWINEXTSN
  34 #define _DARWIN_UNLIMITED_STREAMS
  35 #define COUNT   0
  36 #elif defined(VARIANT_LEGACY)
  37 #define COUNT   0
  38 #else
  39 #define COUNT   1
  40 #endif
  41
  42 #if defined(LIBC_SCCS) && !defined(lint)
  43 static char sccsid[] = "@(#)fopen.c     8.1 (Berkeley) 6/4/93";
  44 #endif /* LIBC_SCCS and not lint */
  45 #include <sys/cdefs.h>
  46 __FBSDID("$FreeBSD: src/lib/libc/stdio/fopen.c,v 1.14 2008/04/22 17:03:32 jhb Exp $");
  47
  48 #include "namespace.h"
  49 #include <sys/types.h>
  50 #include <sys/stat.h>
  51 #include <fcntl.h>
  52 #include <unistd.h>
  53 #include <stdio.h>
  54 #include <errno.h>
  55 #include <limits.h>
  56 #include "un-namespace.h"
  57
  58 #include "local.h"
  59
  60 FILE *
  61 fopen(file, mode)
  62         const char * __restrict file;
  63         const char * __restrict mode;
  64 {
  65         FILE *fp;
  66         int f;
  67         int flags, oflags;
  68
  69         if ((flags = __sflags(mode, &oflags)) == 0)
  70                 return (NULL);
  71         if ((fp = __sfp(COUNT)) == NULL)
  72                 return (NULL);
  73         if ((f = _open(file, oflags, DEFFILEMODE)) < 0) {
  74                 __sfprelease(fp);               /* release */
  75                 return (NULL);
  76         }
  77         /*
  78          * File descriptors are a full int, but _file is only a short.
  79          * If we get a valid file descriptor that is greater than
  80          * SHRT_MAX, then the fd will get sign-extended into an
  81          * invalid file descriptor.  Handle this case by failing the
  82          * open.
  83          */
  84         if (f > SHRT_MAX) {
  85                 fp->_flags = 0;                 /* release */
  86                 _close(f);
  87                 errno = EMFILE;
  88                 return (NULL);
  89         }
  90         fp->_file = f;
  91         fp->_flags = flags;
  92         fp->_cookie = fp;
  93         fp->_read = __sread;
  94         fp->_write = __swrite;
  95         fp->_seek = __sseek;
  96         fp->_close = __sclose;
  97         /*
  98          * When opening in append mode, even though we use O_APPEND,
  99          * we need to seek to the end so that ftell() gets the right
 100          * answer.  If the user then alters the seek pointer, or
 101          * the file extends, this will fail, but there is not much
 102          * we can do about this.  (We could set __SAPP and check in
 103          * fseek and ftell.)
 104          */
 105         if (oflags & O_APPEND)
 106                 (void)_sseek(fp, (fpos_t)0, SEEK_END);
 107         return (fp);
 108 }