lib/libc/stdio/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  * 3. 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("$FreeBSD$");
  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(int fd, const char *mode)
  51 {
  52         FILE *fp;
  53         int flags, oflags, fdflags, tmp;
  54
  55         /*
  56          * File descriptors are a full int, but _file is only a short.
  57          * If we get a valid file descriptor that is greater than
  58          * SHRT_MAX, then the fd will get sign-extended into an
  59          * invalid file descriptor.  Handle this case by failing the
  60          * open.
  61          */
  62         if (fd > SHRT_MAX) {
  63                 errno = EMFILE;
  64                 return (NULL);
  65         }
  66
  67         if ((flags = __sflags(mode, &oflags)) == 0)
  68                 return (NULL);
  69
  70         /* Make sure the mode the user wants is a subset of the actual mode. */
  71         if ((fdflags = _fcntl(fd, F_GETFL, 0)) < 0)
  72                 return (NULL);
  73         /* Work around incorrect O_ACCMODE. */
  74         tmp = fdflags & (O_ACCMODE | O_EXEC);
  75         if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
  76                 errno = EINVAL;
  77                 return (NULL);
  78         }
  79
  80         if ((fp = __sfp()) == NULL)
  81                 return (NULL);
  82
  83         if ((oflags & O_CLOEXEC) && _fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) {
  84                 fp->_flags = 0;
  85                 return (NULL);
  86         }
  87
  88         fp->_flags = flags;
  89         /*
  90          * If opened for appending, but underlying descriptor does not have
  91          * O_APPEND bit set, assert __SAPP so that __swrite() caller
  92          * will _sseek() to the end before write.
  93          */
  94         if (fdflags & O_APPEND)
  95                 fp->_flags2 |= __S2OAP;
  96         else if (oflags & O_APPEND)
  97                 fp->_flags |= __SAPP;
  98         fp->_file = fd;
  99         fp->_cookie = fp;
 100         fp->_read = __sread;
 101         fp->_write = __swrite;
 102         fp->_seek = __sseek;
 103         fp->_close = __sclose;
 104         return (fp);
 105 }