Category : C++ Source Code
Archive : VCCRT2.ZIP
Filename : FFLUSH.C
Output of file : FFLUSH.C contained in archive : VCCRT2.ZIP
*fflush.c - flush a stream buffer
*
* Copyright (c) 1985-1992, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines fflush() - flush the buffer on a stream
* flushall() - flush all stream buffers
*
*******************************************************************************/
#include
#include
#include
#include
#include
#include
/* Values passed to flsall() to distinguish between flushall() and
* fflush(NULL) behavior
*/
#define FLUSHALL 1
#define FFLUSHNULL 0
/* Core routine for fflush(NULL) and flushall()
*/
static int near pascal flsall(int);
/***
*int fflush(stream) - flush the buffer on a stream
*
*Purpose:
* if file open for writing and buffered, flush the buffer. if problems
* flushing the buffer, set the stream flag to error
* Always flushes the stdio stream and forces a commit to disk if file
* was opened in commit mode.
*
*Entry:
* FILE *stream - stream to flush
*
*Exit:
* returns 0 if flushed successfully, or no buffer to flush
* returns EOF and sets file error flag if fails.
* FILE struct entries affected: _ptr, _cnt, _flag.
*
*Exceptions:
*
*******************************************************************************/
int fflush (
FILE *str
)
{
REG1 FILE2 _NEAR_ *stream2;
/* if stream is NULL, flush all streams */
if ( str == NULL ) {
return(flsall(FFLUSHNULL));
}
if (_flush(str) != 0) {
/* _flush failed, don't attempt to commit */
return(EOF);
}
/* lowio commit to ensure data is written to disk */
stream2 = &(_iob2_((FILE _NEAR_ *)FP_OFF(str)));
if (stream2->_flag2 & _IOCOMMIT) {
return (_commit(_fileno(str)) ? EOF : 0);
}
}
/***
*int _flush(stream) - flush the buffer on a single stream
*
*Purpose:
* if file open for writing and buffered, flush the buffer. if problems
* flushing the buffer, set the stream flag to error
* Multi-thread version assumes stream lock is held by caller
*
*Entry:
* FILE *stream - stream to flush
*
*Exit:
* returns 0 if flushed successfully, or no buffer to flush
* returns EOF and sets file error flag if fails.
* FILE struct entries affected: _ptr, _cnt, _flag.
*
*Exceptions:
*
*******************************************************************************/
int near _flush (
FILE *str
)
{
REG1 FILE _NEAR_ *stream;
REG2 int rc = 0; /* assume good return */
REG3 int nchar;
/* Init near pointer to stream */
stream = (FILE _NEAR_ *) FP_OFF(str);
if ((stream->_flag & (_IOREAD | _IOWRT)) == _IOWRT && bigbuf(stream)
&& (nchar = stream->_ptr - stream->_base) > 0)
{
if ( _write(_fileno(stream), stream->_base, nchar) == nchar ) {
/* if this is a read/write file, clear _IOWRT so that
* next operation can be a read
*/
if ( _IORW & stream->_flag )
stream->_flag &= ~_IOWRT;
}
else {
stream->_flag |= _IOERR;
rc = EOF;
}
}
stream->_ptr = stream->_base;
stream->_cnt = 0;
return(rc);
}
/***
*int _flushall() - flush all output buffers
*
*Purpose:
* flushes all the output buffers to the file, clears all input buffers.
*
*Entry:
* None.
*
*Exit:
* returns number of open streams
*
*Exceptions:
*
*******************************************************************************/
int _flushall (
void
)
{
return(flsall(FLUSHALL));
}
/***
*static int near pascal flsall(flushflag) - flush all output buffers
*
*Purpose:
* Flushes all the output buffers to the file and, if FLUSHALL is passed,
* clears all input buffers. Core routine for both fflush(NULL) and
* flushall().
*
* MTHREAD Note: All the locking/unlocking required for both fflush(NULL)
* and flushall() is performed in this routine.
*
*Entry:
* int flushflag - flag indicating the exact semantics, there are two
* legal values: FLUSHALL and FFLUSHNULL
*
*Exit:
* if flushflag == FFLUSHNULL then flsbuf returns:
* 0, if successful
* EOF, if an error occurs while flushing one of the streams
*
* if flushflag == FLUSHALL then flsbuf returns the number of streams
* successfully flushed
*
*Exceptions:
*
*******************************************************************************/
static int near pascal flsall (
int flushflag
)
{
REG1 FILE _NEAR_ *stream = _iob;
REG2 int count = 0;
int errcode = 0;
for (; stream <= _lastiob; stream++) {
if ( (flushflag == FLUSHALL) && inuse(stream) ) {
/* FLUSHALL functionality: fflush the read or write
* stream and, if successful, update the count of
* flushed streams
*/
if ( fflush(stream) != EOF )
/* update count of successfully flushed
* streams
*/
count++;
}
else if ( (flushflag == FFLUSHNULL) &&
(stream->_flag & _IOWRT) ) {
/* FFLUSHNULL functionality: fflush the write stream
* and kept track of the error, if one occurs
*/
if ( fflush(stream) == EOF )
errcode = EOF;
}
}
if ( flushflag == FLUSHALL )
return(count);
else
return(errcode);
}
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