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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

<<fflush>>---flush buffered file output

INDEX

        fflush

ANSI_SYNOPSIS

        #include <stdio.h>

        int fflush(FILE *<[fp]>);

TRAD_SYNOPSIS

        #include <stdio.h>

        int fflush(<[fp]>)

        FILE *<[fp]>;

DESCRIPTION

The <<stdio>> output functions can buffer output before delivering it

to the host system, in order to minimize the overhead of system calls.

Use <<fflush>> to deliver any such pending output (for the file

or stream identified by <[fp]>) to the host system.

If <[fp]> is <<NULL>>, <<fflush>> delivers pending output from all

open files.

RETURNS

<<fflush>> returns <<0>> unless it encounters a write error; in that

situation, it returns <<EOF>>.

PORTABILITY

ANSI C requires <<fflush>>.

No supporting OS subroutines are required.

*/

#include <stdio.h>

#include "local.h"

/* Flush a single file, or (if fp is NULL) all files.  */

int

_DEFUN (fflush, (fp),

        register FILE * fp)

{

  register unsigned char *p;

  register int n, t;

  if (fp == NULL)

    return _fwalk (_REENT, fflush);

  CHECK_INIT (fp);

  t = fp->_flags;

  if ((t & __SWR) == 0 || (p = fp->_bf._base) == NULL)

    return 0;

  n = fp->_p - p;               /* write this much */

  /*

   * Set these immediately to avoid problems with longjmp

   * and to allow exchange buffering (via setvbuf) in user

   * write function.

   */

  fp->_p = p;

  fp->_w = t & (__SLBF | __SNBF) ? 0 : fp->_bf._size;

  while (n > 0)

    {

      t = (*fp->_write) (fp->_cookie, (char *) p, n);

      if (t <= 0)

        {

          fp->_flags |= __SERR;

          return EOF;

        }

      p += t;

      n -= t;

    }

  return 0;

}