mirror of https://github.com/lianthony/NT4.0
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
95 lines
2.5 KiB
95 lines
2.5 KiB
/***
|
|
*stream.c - find a stream not in use
|
|
*
|
|
* Copyright (c) 1985-1992, Microsoft Corporation. All rights reserved.
|
|
*
|
|
*Purpose:
|
|
* defines _getstream() - find a stream not in use
|
|
*
|
|
*Revision History:
|
|
* 09-02-83 RN initial version
|
|
* 11-01-87 JCR Multi-thread support
|
|
* 05-24-88 PHG Merged DLL and normal versions
|
|
* 06-10-88 JCR Use near pointer to reference _iob[] entries
|
|
* 08-17-89 GJF Removed _NEAR_, fixed copyright and indenting.
|
|
* 02-16-90 GJF Fixed copyright
|
|
* 03-19-90 GJF Made calling type _CALLTYPE1, added #include
|
|
* <cruntime.h> and removed #include <register.h>.
|
|
* 10-03-90 GJF New-style function declarator.
|
|
* 12-31-91 GJF Improved multi-thread lock usage [_WIN32_].
|
|
*
|
|
*******************************************************************************/
|
|
|
|
#include <cruntime.h>
|
|
#include <stdio.h>
|
|
#include <file2.h>
|
|
#include <internal.h>
|
|
#include <os2dll.h>
|
|
|
|
/***
|
|
*FILE *_getstream() - find a stream not in use
|
|
*
|
|
*Purpose:
|
|
* find a stream not in use and make it available to caller. _lastiob is
|
|
* the last FILE address. intended for use inside library only
|
|
*
|
|
*Entry:
|
|
* None. Reads _iob.
|
|
*
|
|
*Exit:
|
|
* returns a pointer to a free stream, or NULL if all are in use. A
|
|
* stream becomes allocated if the caller decided to use it by setting
|
|
* any r, w, r/w mode.
|
|
*
|
|
* Note: Optimized the code to use a near pointer for the stream. This
|
|
* is especially helpful in large model. However, the drawback is that we
|
|
* need another temporary 'retval' so that when we return NULL, we return
|
|
* 0:0, not DS:0.
|
|
*
|
|
* [Multi-thread note: If a free stream is found, it is returned in a
|
|
* LOCKED state. It is the caller's responsibility to unlock the stream.]
|
|
*
|
|
*Exceptions:
|
|
*
|
|
*******************************************************************************/
|
|
|
|
FILE * _CALLTYPE1 _getstream (
|
|
void
|
|
)
|
|
{
|
|
REG1 FILE *stream = _iob;
|
|
REG2 FILE *retval = NULL;
|
|
#ifdef MTHREAD
|
|
int index;
|
|
#endif
|
|
|
|
/* Get the iob[] scan lock */
|
|
_mlock(_IOB_SCAN_LOCK);
|
|
|
|
/* Loop through the _iob table looking for a free stream.*/
|
|
for (; stream <= _lastiob; stream++) {
|
|
|
|
if ( !inuse(stream) ) {
|
|
#ifdef MTHREAD
|
|
index = _iob_index(stream);
|
|
_lock_str(index);
|
|
|
|
/* make sure the _iob entry is still free */
|
|
if ( inuse(stream) ) {
|
|
/* no longer free! release the lock and
|
|
continue looping */
|
|
_unlock_str(index);
|
|
continue;
|
|
}
|
|
#endif
|
|
stream->_flag = stream->_cnt = 0;
|
|
stream->_ptr = stream->_base = NULL;
|
|
stream->_file = -1;
|
|
retval = stream;
|
|
break;
|
|
}
|
|
}
|
|
|
|
_munlock(_IOB_SCAN_LOCK);
|
|
return(retval);
|
|
}
|