lib/libc/stdio/fdopen.c

   1 /*      $NetBSD: fdopen.c,v 1.16 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[] = "@(#)fdopen.c    8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: fdopen.c,v 1.16 2012/03/15 18:22:30 christos Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include "namespace.h"
  45 #include <sys/types.h>
  46
  47 #include <assert.h>
  48 #include <errno.h>
  49 #include <fcntl.h>
  50 #include <unistd.h>
  51 #include <stdio.h>
  52 #include <limits.h>
  53
  54 #include "reentrant.h"
  55 #include "local.h"
  56
  57 #ifdef __weak_alias
  58 __weak_alias(fdopen,_fdopen)
  59 #endif
  60
  61 FILE *
  62 fdopen(int fd, const char *mode)
  63 {
  64         FILE *fp;
  65         int flags, oflags, fdflags, tmp;
  66
  67         _DIAGASSERT(fd != -1);
  68
  69         /*
  70          * File descriptors are a full int, but _file is only a short.
  71          * If we get a valid file descriptor that is greater or equal to
  72          * USHRT_MAX, then the fd will get sign-extended into an
  73          * invalid file descriptor.  Handle this case by failing the
  74          * open. (We treat the short as unsigned, and special-case -1).
  75          */
  76         if (fd >= USHRT_MAX) {
  77                 errno = EMFILE;
  78                 return NULL;
  79         }
  80
  81         if ((flags = __sflags(mode, &oflags)) == 0)
  82                 return NULL;
  83
  84         /* Make sure the mode the user wants is a subset of the actual mode. */
  85         if ((fdflags = fcntl(fd, F_GETFL, 0)) < 0)
  86                 return NULL;
  87         tmp = fdflags & O_ACCMODE;
  88         if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
  89                 errno = EINVAL;
  90                 return NULL;
  91         }
  92
  93         if (oflags & O_NONBLOCK) {
  94                 struct stat st;
  95                 if (fstat(fd, &st) == -1) {
  96                         return NULL;
  97                 }
  98                 if (!S_ISREG(st.st_mode)) {
  99                         errno = EFTYPE;
 100                         return NULL;
 101                 }
 102         }
 103
 104         if ((fp = __sfp()) == NULL)
 105                 return NULL;
 106         fp->_flags = flags;
 107         /*
 108          * If opened for appending, but underlying descriptor does not have
 109          * O_APPEND bit set, assert __SAPP so that __swrite() will lseek to
 110          * end before each write.
 111          */
 112         if ((oflags & O_APPEND) && !(fdflags & O_APPEND))
 113                 fp->_flags |= __SAPP;
 114         fp->_file = fd;
 115         fp->_cookie = fp;
 116         fp->_read = __sread;
 117         fp->_write = __swrite;
 118         fp->_seek = __sseek;
 119         fp->_close = __sclose;
 120         return fp;
 121 }