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/*

 * Copyright (c) 1990 The Regents of the University of California.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms are permitted

 * provided that the above copyright notice and this paragraph are

 * duplicated in all such forms and that any documentation,

 * advertising materials, and other materials related to such

 * distribution and use acknowledge that the software was developed

 * by the University of California, Berkeley.  The name of the

 * University may not be used to endorse or promote products derived

 * from this software without specific prior written permission.

 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

 */

/*

FUNCTION

<<freopen>>---open a file using an existing file descriptor

INDEX

        freopen

ANSI_SYNOPSIS

        #include <stdio.h>

        FILE *freopen(const char *<[file]>, const char *<[mode]>,

                      FILE *<[fp]>);

TRAD_SYNOPSIS

        #include <stdio.h>

        FILE *freopen(<[file]>, <[mode]>, <[fp]>)

        char *<[file]>;

        char *<[mode]>;

        FILE *<[fp]>;

DESCRIPTION

Use this variant of <<fopen>> if you wish to specify a particular file

descriptor <[fp]> (notably <<stdin>>, <<stdout>>, or <<stderr>>) for

the file.

If <[fp]> was associated with another file or stream, <<freopen>>

closes that other file or stream (but ignores any errors while closing

it).

<[file]> and <[mode]> are used just as in <<fopen>>.

RETURNS

If successful, the result is the same as the argument <[fp]>.  If the

file cannot be opened as specified, the result is <<NULL>>.

PORTABILITY

ANSI C requires <<freopen>>.

Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,

<<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>.

*/

#include <time.h>

#include <stdio.h>

#include <fcntl.h>

#include <stdlib.h>

#include "local.h"

/*

 * Re-direct an existing, open (probably) file to some other file.

 */

FILE *

_DEFUN (freopen, (file, mode, fp),

        _CONST char *file _AND

        _CONST char *mode _AND

        register FILE *fp)

{

  register int f;

  int flags, oflags, e;

  struct _reent *ptr;

  CHECK_INIT (fp);

  ptr = fp->_data;

  if ((flags = __sflags (ptr, mode, &oflags)) == 0)

    {

      (void) fclose (fp);

      return NULL;

    }

  /*

   * Remember whether the stream was open to begin with, and

   * which file descriptor (if any) was associated with it.

   * If it was attached to a descriptor, defer closing it,

   * so that, e.g., freopen("/dev/stdin", "r", stdin) works.

   * This is unnecessary if it was not a Unix file.

   */

  if (fp->_flags == 0)

    fp->_flags = __SEOF;        /* hold on to it */

  else

    {

      if (fp->_flags & __SWR)

        (void) fflush (fp);

      /* if close is NULL, closing is a no-op, hence pointless */

      if (fp->_close != NULL)

        (void) (*fp->_close) (fp->_cookie);

    }

  /*

   * Now get a new descriptor to refer to the new file.

   */

  f = _open_r (ptr, (char *) file, oflags, 0666);

  e = ptr->_errno;

  /*

   * Finish closing fp.  Even if the open succeeded above,

   * we cannot keep fp->_base: it may be the wrong size.

   * This loses the effect of any setbuffer calls,

   * but stdio has always done this before.

   */

  if (fp->_flags & __SMBF)

    _free_r (ptr, (char *) fp->_bf._base);

  fp->_w = 0;

  fp->_r = 0;

  fp->_p = NULL;

  fp->_bf._base = NULL;

  fp->_bf._size = 0;

  fp->_lbfsize = 0;

  if (HASUB (fp))

    FREEUB (fp);

  fp->_ub._size = 0;

  if (HASLB (fp))

    FREELB (fp);

  fp->_lb._size = 0;

  if (f < 0)

    {                           /* did not get it after all */

      fp->_flags = 0;            /* set it free */

      ptr->_errno = e;          /* restore in case _close clobbered */

      return NULL;

    }

  fp->_flags = flags;

  fp->_file = f;

  fp->_cookie = (_PTR) fp;

  fp->_read = __sread;

  fp->_write = __swrite;

  fp->_seek = __sseek;

  fp->_close = __sclose;

#ifdef __SCLE

  if (__stextmode(fp->_file))

    fp->_flags |= __SCLE;

#endif

  return fp;

}