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/*
* (c) The GRASP/AQUA Project, Glasgow University, 1994-1998
*
* $Id: flushFile.c,v 1.7 2000/04/12 17:33:16 simonmar Exp $
*
* hFlush Runtime Support
*/
#include "Rts.h"
#include "stgio.h"
StgInt
flushFile(StgForeignPtr ptr)
{
IOFileObject* fo = (IOFileObject*)ptr;
int rc = 0;
if ( (fo->flags & FILEOBJ_WRITE) && FILEOBJ_NEEDS_FLUSHING(fo) ) {
rc = writeBuffer(ptr,fo->bufWPtr - fo->bufRPtr);
}
return rc;
}
StgInt
flushBuffer(StgForeignPtr ptr)
{
IOFileObject* fo = (IOFileObject*)ptr;
int rc = 0;
/* If the file object is writeable, or if it's
RW *and* the last operation on it was a write,
flush it.
*/
if ( (!FILEOBJ_READABLE(fo) && FILEOBJ_WRITEABLE(fo)) ||
(FILEOBJ_RW(fo) && FILEOBJ_JUST_WRITTEN(fo)) ) {
rc = flushFile(ptr);
if (rc<0) return rc;
}
/* TODO: shouldn't we do the lseek stuff from flushReadBuffer
* here???? --SDM
*/
/* Reset read & write pointer for input buffers */
if ( (fo->flags & FILEOBJ_READ) ) {
fo->bufRPtr=0;
fo->bufWPtr=0;
}
return 0;
}
/*
For RW file objects, flushing input buffers doesn't just involve
resetting the read & write pointers, we also have to change the
underlying file position to point to the effective read position.
(Sigh, I now understand the real reason for why stdio opted for
the solution of leaving this to the programmer!)
*/
StgInt
flushReadBuffer(StgForeignPtr ptr)
{
IOFileObject* fo = (IOFileObject*)ptr;
int delta;
delta = fo->bufWPtr - fo->bufRPtr;
if ( delta > 0 ) {
while ( lseek(fo->fd, -delta, SEEK_CUR) == -1) {
if (errno != EINTR) {
cvtErrno();
stdErrno();
return -1;
}
}
}
fo->bufRPtr=0;
fo->bufWPtr=0;
return 0;
}
void
flushConnectedBuf(StgForeignPtr ptr)
{
StgInt rc;
IOFileObject* fo = (IOFileObject*)ptr;
/* if the stream is connected to an output stream, flush it. */
if ( fo->connectedTo != NULL && fo->connectedTo->fd != -1 &&
(fo->connectedTo->flags & FILEOBJ_WRITE) ) {
rc = flushBuffer((StgForeignPtr)fo->connectedTo);
}
/* Willfully ignore the return code for now. */
return;
}
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