lib/libc/stdio/fopen.c

   1 /*      $NetBSD: fopen.c,v 1.15 2012/03/15 18:22:30 christos Exp $      */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)fopen.c     8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: fopen.c,v 1.15 2012/03/15 18:22:30 christos Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include <sys/types.h>
  45 #include <sys/stat.h>
  46 #include <assert.h>
  47 #include <fcntl.h>
  48 #include <unistd.h>
  49 #include <stdio.h>
  50 #include <errno.h>
  51 #include <limits.h>
  52 #include "reentrant.h"
  53 #include "local.h"
  54
  55 FILE *
  56 fopen(const char *file, const char *mode)
  57 {
  58         FILE *fp;
  59         int f;
  60         int flags, oflags;
  61
  62         _DIAGASSERT(file != NULL);
  63         if ((flags = __sflags(mode, &oflags)) == 0)
  64                 return NULL;
  65         if ((fp = __sfp()) == NULL)
  66                 return NULL;
  67         if ((f = open(file, oflags, DEFFILEMODE)) < 0)
  68                 goto release;
  69         if (oflags & O_NONBLOCK) {
  70                 struct stat st;
  71                 if (fstat(f, &st) == -1) {
  72                         int sverrno = errno;
  73                         (void)close(f);
  74                         errno = sverrno;
  75                         goto release;
  76                 }
  77                 if (!S_ISREG(st.st_mode)) {
  78                         (void)close(f);
  79                         errno = EFTYPE;
  80                         goto release;
  81                 }
  82         }
  83         /*
  84          * File descriptors are a full int, but _file is only a short.
  85          * If we get a valid file descriptor that is greater or equal to
  86          * USHRT_MAX, then the fd will get sign-extended into an
  87          * invalid file descriptor.  Handle this case by failing the
  88          * open. (We treat the short as unsigned, and special-case -1).
  89          */
  90         if (f >= USHRT_MAX) {
  91                 errno = EMFILE;
  92                 goto release;
  93         }
  94
  95         fp->_file = f;
  96         fp->_flags = flags;
  97         fp->_cookie = fp;
  98         fp->_read = __sread;
  99         fp->_write = __swrite;
 100         fp->_seek = __sseek;
 101         fp->_close = __sclose;
 102
 103         /*
 104          * When opening in append mode, even though we use O_APPEND,
 105          * we need to seek to the end so that ftell() gets the right
 106          * answer.  If the user then alters the seek pointer, or
 107          * the file extends, this will fail, but there is not much
 108          * we can do about this.  (We could set __SAPP and check in
 109          * fseek and ftell.)
 110          */
 111         if (oflags & O_APPEND)
 112                 (void) __sseek((void *)fp, (off_t)0, SEEK_END);
 113         return fp;
 114 release:
 115         fp->_flags = 0;                 /* release */
 116         return NULL;
 117 }