stdio/FreeBSD/fdopen.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[] = "@(#)fdopen.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/fdopen.c,v 1.11 2008/05/10 18:39:20 antoine Exp $");
  38
  39 #include "namespace.h"
  40 #include <sys/types.h>
  41 #include <fcntl.h>
  42 #include <unistd.h>
  43 #include <stdio.h>
  44 #include <errno.h>
  45 #include <limits.h>
  46 #include "un-namespace.h"
  47 #include "local.h"
  48
  49 FILE *
  50 fdopen(fd, mode)
  51         int fd;
  52         const char *mode;
  53 {
  54         FILE *fp;
  55         int flags, oflags, fdflags, tmp;
  56
  57         /*
  58          * File descriptors are a full int, but _file is only a short.
  59          * If we get a valid file descriptor that is greater than
  60          * SHRT_MAX, then the fd will get sign-extended into an
  61          * invalid file descriptor.  Handle this case by failing the
  62          * open.
  63          */
  64         if (fd > SHRT_MAX) {
  65                 errno = EMFILE;
  66                 return (NULL);
  67         }
  68
  69         if ((flags = __sflags(mode, &oflags)) == 0)
  70                 return (NULL);
  71
  72         /* Make sure the mode the user wants is a subset of the actual mode. */
  73         if ((fdflags = _fcntl(fd, F_GETFL, 0)) < 0)
  74                 return (NULL);
  75         tmp = fdflags & O_ACCMODE;
  76         if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
  77                 errno = EINVAL;
  78                 return (NULL);
  79         }
  80
  81         if ((fp = __sfp()) == NULL)
  82                 return (NULL);
  83         fp->_flags = flags;
  84         /*
  85          * If opened for appending, but underlying descriptor does not have
  86          * O_APPEND bit set, assert __SAPP so that __swrite() caller
  87          * will _sseek() to the end before write.
  88          */
  89         if ((oflags & O_APPEND) && !(fdflags & O_APPEND))
  90                 fp->_flags |= __SAPP;
  91         fp->_file = fd;
  92         fp->_cookie = fp;
  93         fp->_read = __sread;
  94         fp->_write = __swrite;
  95         fp->_seek = __sseek;
  96         fp->_close = __sclose;
  97         return (fp);
  98 }