115 lines
2.8 KiB
C
115 lines
2.8 KiB
C
/*
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* Copyright (c) 1990 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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<<fflush>>---flush buffered file output
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INDEX
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fflush
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ANSI_SYNOPSIS
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#include <stdio.h>
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int fflush(FILE *<[fp]>);
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TRAD_SYNOPSIS
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#include <stdio.h>
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int fflush(<[fp]>)
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FILE *<[fp]>;
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DESCRIPTION
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The <<stdio>> output functions can buffer output before delivering it
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to the host system, in order to minimize the overhead of system calls.
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Use <<fflush>> to deliver any such pending output (for the file
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or stream identified by <[fp]>) to the host system.
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If <[fp]> is <<NULL>>, <<fflush>> delivers pending output from all
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open files.
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RETURNS
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<<fflush>> returns <<0>> unless it encounters a write error; in that
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situation, it returns <<EOF>>.
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PORTABILITY
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ANSI C requires <<fflush>>.
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No supporting OS subroutines are required.
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*/
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#include <_ansi.h>
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#include <stdio.h>
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#include "local.h"
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/* Flush a single file, or (if fp is NULL) all files. */
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int
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_DEFUN(fflush, (fp),
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register FILE * fp)
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{
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register unsigned char *p;
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register int n, t;
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if (fp == NULL)
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return _fwalk (_GLOBAL_REENT, fflush);
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CHECK_INIT (_REENT, fp);
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_flockfile (fp);
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t = fp->_flags;
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if ((t & __SWR) == 0)
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{
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/* For a read stream, an fflush causes the next seek to be
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unoptimized (i.e. forces a system-level seek). This conforms
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to the POSIX and SUSv3 standards. */
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fp->_flags |= __SNPT;
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_funlockfile (fp);
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return 0;
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}
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if ((p = fp->_bf._base) == NULL)
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{
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/* Nothing to flush. */
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_funlockfile (fp);
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return 0;
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}
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n = fp->_p - p; /* write this much */
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/*
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* Set these immediately to avoid problems with longjmp
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* and to allow exchange buffering (via setvbuf) in user
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* write function.
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*/
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fp->_p = p;
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fp->_w = t & (__SLBF | __SNBF) ? 0 : fp->_bf._size;
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while (n > 0)
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{
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t = (*fp->_write) (fp->_cookie, (char *) p, n);
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if (t <= 0)
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{
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fp->_flags |= __SERR;
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_funlockfile (fp);
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return EOF;
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}
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p += t;
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n -= t;
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}
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_funlockfile (fp);
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return 0;
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}
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