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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libc/] [stdio/] [freopen.c] - Blame information for rev 158

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1 148 jeremybenn
/*
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 * Copyright (c) 1990, 2007 The Regents of the University of California.
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms are permitted
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 * provided that the above copyright notice and this paragraph are
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 * duplicated in all such forms and that any documentation,
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 * advertising materials, and other materials related to such
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 * distribution and use acknowledge that the software was developed
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 * by the University of California, Berkeley.  The name of the
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 * University may not be used to endorse or promote products derived
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 * from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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 */
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/*
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FUNCTION
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<<freopen>>---open a file using an existing file descriptor
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INDEX
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        freopen
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INDEX
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        _freopen_r
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ANSI_SYNOPSIS
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        #include <stdio.h>
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        FILE *freopen(const char *<[file]>, const char *<[mode]>,
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                      FILE *<[fp]>);
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        FILE *_freopen_r(struct _reent *<[ptr]>, const char *<[file]>,
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                      const char *<[mode]>, FILE *<[fp]>);
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TRAD_SYNOPSIS
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        #include <stdio.h>
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        FILE *freopen(<[file]>, <[mode]>, <[fp]>)
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        char *<[file]>;
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        char *<[mode]>;
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        FILE *<[fp]>;
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        FILE *_freopen_r(<[ptr]>, <[file]>, <[mode]>, <[fp]>)
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        struct _reent *<[ptr]>;
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        char *<[file]>;
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        char *<[mode]>;
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        FILE *<[fp]>;
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DESCRIPTION
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Use this variant of <<fopen>> if you wish to specify a particular file
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descriptor <[fp]> (notably <<stdin>>, <<stdout>>, or <<stderr>>) for
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the file.
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If <[fp]> was associated with another file or stream, <<freopen>>
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closes that other file or stream (but ignores any errors while closing
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it).
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<[file]> and <[mode]> are used just as in <<fopen>>.
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If <[file]> is <<NULL>>, the underlying stream is modified rather than
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closed.  The file cannot be given a more permissive access mode (for
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example, a <[mode]> of "w" will fail on a read-only file descriptor),
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but can change status such as append or binary mode.  If modification
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is not possible, failure occurs.
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RETURNS
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If successful, the result is the same as the argument <[fp]>.  If the
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file cannot be opened as specified, the result is <<NULL>>.
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PORTABILITY
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ANSI C requires <<freopen>>.
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Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
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<<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>.
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*/
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#include <_ansi.h>
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#include <reent.h>
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#include <time.h>
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <sys/lock.h>
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#include "local.h"
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/*
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 * Re-direct an existing, open (probably) file to some other file.
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 */
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FILE *
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_DEFUN(_freopen_r, (ptr, file, mode, fp),
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       struct _reent *ptr _AND
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       const char *file _AND
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       const char *mode _AND
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       register FILE *fp)
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{
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  register int f;
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  int flags, oflags;
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  int e = 0;
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  __sfp_lock_acquire ();
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  CHECK_INIT (ptr, fp);
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  _flockfile (fp);
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  if ((flags = __sflags (ptr, mode, &oflags)) == 0)
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    {
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      _funlockfile (fp);
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      _fclose_r (ptr, fp);
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      __sfp_lock_release ();
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      return NULL;
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    }
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  /*
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   * Remember whether the stream was open to begin with, and
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   * which file descriptor (if any) was associated with it.
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   * If it was attached to a descriptor, defer closing it,
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   * so that, e.g., freopen("/dev/stdin", "r", stdin) works.
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   * This is unnecessary if it was not a Unix file.
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   */
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  if (fp->_flags == 0)
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    fp->_flags = __SEOF;        /* hold on to it */
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  else
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    {
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      if (fp->_flags & __SWR)
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        _fflush_r (ptr, fp);
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      /*
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       * If close is NULL, closing is a no-op, hence pointless.
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       * If file is NULL, the file should not be closed.
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       */
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      if (fp->_close != NULL && file != NULL)
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        fp->_close (ptr, fp->_cookie);
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    }
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  /*
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   * Now get a new descriptor to refer to the new file, or reuse the
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   * existing file descriptor if file is NULL.
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   */
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  if (file != NULL)
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    {
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      f = _open_r (ptr, (char *) file, oflags, 0666);
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      e = ptr->_errno;
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    }
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  else
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    {
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#ifdef HAVE_FCNTL
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      int oldflags;
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      /*
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       * Reuse the file descriptor, but only if the new access mode is
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       * equal or less permissive than the old.  F_SETFL correctly
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       * ignores creation flags.
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       */
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      f = fp->_file;
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      if ((oldflags = _fcntl_r (ptr, f, F_GETFL, 0)) == -1
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          || ! ((oldflags & O_ACCMODE) == O_RDWR
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                || ((oldflags ^ oflags) & O_ACCMODE) == 0)
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          || _fcntl_r (ptr, f, F_SETFL, oflags) == -1)
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        f = -1;
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#else
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      /* We cannot modify without fcntl support.  */
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      f = -1;
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#endif
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#ifdef __SCLE
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      /*
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       * F_SETFL doesn't change textmode.  Don't mess with modes of ttys.
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       */
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      if (0 <= f && ! _isatty_r (ptr, f)
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          && setmode (f, oflags & (O_BINARY | O_TEXT)) == -1)
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        f = -1;
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#endif
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      if (f < 0)
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        {
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          e = EBADF;
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          if (fp->_close != NULL)
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            fp->_close (ptr, fp->_cookie);
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        }
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    }
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  /*
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   * Finish closing fp.  Even if the open succeeded above,
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   * we cannot keep fp->_base: it may be the wrong size.
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   * This loses the effect of any setbuffer calls,
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   * but stdio has always done this before.
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   */
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  if (fp->_flags & __SMBF)
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    _free_r (ptr, (char *) fp->_bf._base);
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  fp->_w = 0;
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  fp->_r = 0;
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  fp->_p = NULL;
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  fp->_bf._base = NULL;
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  fp->_bf._size = 0;
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  fp->_lbfsize = 0;
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  if (HASUB (fp))
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    FREEUB (ptr, fp);
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  fp->_ub._size = 0;
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  if (HASLB (fp))
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    FREELB (ptr, fp);
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  fp->_lb._size = 0;
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  fp->_flags & ~__SORD;
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  fp->_flags2 = 0;
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  memset (&fp->_mbstate, 0, sizeof (_mbstate_t));
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  if (f < 0)
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    {                           /* did not get it after all */
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      fp->_flags = 0;            /* set it free */
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      ptr->_errno = e;          /* restore in case _close clobbered */
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      _funlockfile (fp);
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#ifndef __SINGLE_THREAD__
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      __lock_close_recursive (fp->_lock);
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#endif
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      __sfp_lock_release ();
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      return NULL;
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    }
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  fp->_flags = flags;
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  fp->_file = f;
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  fp->_cookie = (_PTR) fp;
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  fp->_read = __sread;
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  fp->_write = __swrite;
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  fp->_seek = __sseek;
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  fp->_close = __sclose;
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#ifdef __SCLE
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  if (__stextmode (fp->_file))
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    fp->_flags |= __SCLE;
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#endif
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  _funlockfile (fp);
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  __sfp_lock_release ();
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  return fp;
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}
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#ifndef _REENT_ONLY
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FILE *
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_DEFUN(freopen, (file, mode, fp),
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       _CONST char *file _AND
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       _CONST char *mode _AND
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       register FILE *fp)
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{
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  return _freopen_r (_REENT, file, mode, fp);
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}
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#endif /*!_REENT_ONLY */

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