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Tricks of the Windows Gam…ming Gurus (2nd Edition)
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Disc2.iso
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vc98
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crt
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src
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osfinfo.c
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1998-06-17
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/***
*osfinfo.c - Win32 _osfhnd[] support routines
*
* Copyright (c) 1990-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Defines the internally used routine _alloc_osfhnd()
* and the user visible routine _get_osfhandle().
*
*******************************************************************************/
#ifndef _MAC
#include <cruntime.h>
#include <oscalls.h>
#include <errno.h>
#include <internal.h>
#include <fcntl.h>
#include <malloc.h>
#include <msdos.h>
#include <mtdll.h>
#include <stdlib.h>
#include <dbgint.h>
/***
*int _alloc_osfhnd() - get free _ioinfo struct
*
*Purpose:
* Finds the first free entry in the arrays of ioinfo structs and
* returns the index of that entry (which is the CRT file handle to the
* caller) to the caller.
*
*Entry:
* none
*
*Exit:
* returns index of the entry, if successful
* return -1, if no free entry is available
*
* MULTITHREAD NOTE: IF SUCCESSFUL, THE HANDLE IS LOCKED WHEN IT IS
* RETURNED TO THE CALLER!
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _alloc_osfhnd(
void
)
{
int fh = -1; /* file handle */
int i;
ioinfo *pio;
_mlock(_OSFHND_LOCK); /* lock the __pioinfo[] array */
/*
* Search the arrays of ioinfo structs, in order, looking for the
* first free entry. The compound index of this free entry is the
* return value. Here, the compound index of the ioinfo struct
* *(__pioinfo[i] + j) is k = i * IOINFO_ARRAY_ELTS + j, and k = 0,
* 1, 2,... is the order of the search.
*/
for ( i = 0 ; i < IOINFO_ARRAYS ; i++ ) {
/*
* If __pioinfo[i] is non-empty array, search it looking for
* the first free entry. Otherwise, allocate a new array and use
* its first entry.
*/
if ( __pioinfo[i] != NULL ) {
/*
* Search for an available entry.
*/
for ( pio = __pioinfo[i] ;
pio < __pioinfo[i] + IOINFO_ARRAY_ELTS ;
pio++ )
{
if ( (pio->osfile & FOPEN) == 0 ) {
#ifdef _MT
/*
* Make sure the lock is initialized.
*/
if ( pio->lockinitflag == 0 ) {
_mlock( _LOCKTAB_LOCK );
if ( pio->lockinitflag == 0 ) {
InitializeCriticalSection( &(pio->lock) );
pio->lockinitflag++;
}
_munlock( _LOCKTAB_LOCK );
}
EnterCriticalSection( &(pio->lock) );
/*
* Check for the case where another thread has
* managed to grab the handle out from under us.
*/
if ( (pio->osfile & FOPEN) != 0 ) {
LeaveCriticalSection( &(pio->lock) );
continue;
}
#endif /* _MT */
pio->osfhnd = (long)INVALID_HANDLE_VALUE;
fh = i * IOINFO_ARRAY_ELTS + (pio - __pioinfo[i]);
break;
}
}
/*
* Check if a free entry has been found.
*/
if ( fh != -1 )
break;
}
else {
/*
* Allocate and initialize another array of ioinfo structs.
*/
if ( (pio = _malloc_crt( IOINFO_ARRAY_ELTS * sizeof(ioinfo) ))
!= NULL )
{
/*
* Update __pioinfo[] and _nhandle
*/
__pioinfo[i] = pio;
_nhandle += IOINFO_ARRAY_ELTS;
for ( ; pio < __pioinfo[i] + IOINFO_ARRAY_ELTS ; pio++ ) {
pio->osfile = 0;
pio->osfhnd = (long)INVALID_HANDLE_VALUE;
pio->pipech = 10;
#ifdef _MT
pio->lockinitflag = 0;
#endif /* _MT */
}
/*
* The first element of the newly allocated array of ioinfo
* structs, *(__pioinfo[i]), is our first free entry.
*/
fh = i * IOINFO_ARRAY_ELTS;
#ifdef _MT
_lock_fhandle( fh );
#endif /* _MT */
}
break;
}
}
_munlock(_OSFHND_LOCK); /* unlock the __pioinfo[] table */
/*
* return the index of the previously free table entry, if one was
* found. return -1 otherwise.
*/
return( fh );
}
/***
*int _set_osfhnd(int fh, long value) - set Win32 HANDLE value
*
*Purpose:
* If fh is in range and if _osfhnd(fh) is marked with
* INVALID_HANDLE_VALUE then set _osfhnd(fh) to the passed value.
*
*Entry:
* int fh - CRT file handle
* long value - new Win32 HANDLE value for this handle
*
*Exit:
* Returns zero if successful.
* Returns -1 and sets errno to EBADF otherwise.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _set_osfhnd (
int fh,
long value
)
{
if ( ((unsigned)fh < (unsigned)_nhandle) &&
(_osfhnd(fh) == (long)INVALID_HANDLE_VALUE)
) {
if ( __app_type == _CONSOLE_APP ) {
switch (fh) {
case 0:
SetStdHandle( STD_INPUT_HANDLE, (HANDLE)value );
break;
case 1:
SetStdHandle( STD_OUTPUT_HANDLE, (HANDLE)value );
break;
case 2:
SetStdHandle( STD_ERROR_HANDLE, (HANDLE)value );
break;
}
}
_osfhnd(fh) = value;
return(0);
} else {
errno = EBADF; /* bad handle */
_doserrno = 0L; /* not an OS error */
return -1;
}
}
/***
*int _free_osfhnd(int fh) - mark osfhnd field of ioinfo struct as free
*
*Purpose:
* If fh is in range, the corrsponding ioinfo struct is marked as
* being open, and the osfhnd field is NOT set to INVALID_HANDLE_VALUE,
* then mark it with INVALID_HANDLE_VALUE.
*
*Entry:
* int fh - CRT file handle
*
*Exit:
* Returns zero if successful.
* Returns -1 and sets errno to EBADF otherwise.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _free_osfhnd (
int fh /* user's file handle */
)
{
if ( ((unsigned)fh < (unsigned)_nhandle) &&
(_osfile(fh) & FOPEN) &&
(_osfhnd(fh) != (long)INVALID_HANDLE_VALUE) )
{
if ( __app_type == _CONSOLE_APP ) {
switch (fh) {
case 0:
SetStdHandle( STD_INPUT_HANDLE, NULL );
break;
case 1:
SetStdHandle( STD_OUTPUT_HANDLE, NULL );
break;
case 2:
SetStdHandle( STD_ERROR_HANDLE, NULL );
break;
}
}
_osfhnd(fh) = (long)INVALID_HANDLE_VALUE;
return(0);
} else {
errno = EBADF; /* bad handle */
_doserrno = 0L; /* not an OS error */
return -1;
}
}
/***
*long _get_osfhandle(int fh) - get Win32 HANDLE value
*
*Purpose:
* If fh is in range and marked open, return _osfhnd(fh).
*
*Entry:
* int fh - CRT file handle
*
*Exit:
* Returns the Win32 HANDLE successful.
* Returns -1 and sets errno to EBADF otherwise.
*
*Exceptions:
*
*******************************************************************************/
long __cdecl _get_osfhandle (
int fh /* user's file handle */
)
{
if ( ((unsigned)fh < (unsigned)_nhandle) && (_osfile(fh) & FOPEN) )
return( _osfhnd(fh) );
else {
errno = EBADF; /* bad handle */
_doserrno = 0L; /* not an OS error */
return -1;
}
}
/***
*int _open_osfhandle(long osfhandle, int flags) - open C Runtime file handle
*
*Purpose:
* This function allocates a free C Runtime file handle and associates
* it with the Win32 HANDLE specified by the first parameter.
*
*Entry:
* long osfhandle - Win32 HANDLE to associate with C Runtime file handle.
* int flags - flags to associate with C Runtime file handle.
*
*Exit:
* returns index of entry in fh, if successful
* return -1, if no free entry is found
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _open_osfhandle(
long osfhandle,
int flags
)
{
int fh;
char fileflags; /* _osfile flags */
DWORD isdev; /* device indicator in low byte */
/* copy relevant flags from second parameter */
fileflags = 0;
if ( flags & _O_APPEND )
fileflags |= FAPPEND;
if ( flags & _O_TEXT )
fileflags |= FTEXT;
if ( flags & _O_NOINHERIT )
fileflags |= FNOINHERIT;
/* find out what type of file (file/device/pipe) */
isdev = GetFileType((HANDLE)osfhandle);
if (isdev == FILE_TYPE_UNKNOWN) {
/* OS error */
_dosmaperr( GetLastError() ); /* map error */
return -1;
}
/* is isdev value to set flags */
if (isdev == FILE_TYPE_CHAR)
fileflags |= FDEV;
else if (isdev == FILE_TYPE_PIPE)
fileflags |= FPIPE;
/* attempt to allocate a C Runtime file handle */
if ( (fh = _alloc_osfhnd()) == -1 ) {
errno = EMFILE; /* too many open files */
_doserrno = 0L; /* not an OS error */
return -1; /* return error to caller */
}
/*
* the file is open. now, set the info in _osfhnd array
*/
_set_osfhnd(fh, osfhandle);
fileflags |= FOPEN; /* mark as open */
_osfile(fh) = fileflags; /* set osfile entry */
_unlock_fh(fh); /* unlock handle */
return fh; /* return handle */
}
#ifdef _MT
/***
*void _lock_fhandle(int fh) - lock file handle
*
*Purpose:
* Assert the lock associated with the passed file handle.
*
*Entry:
* int fh - CRT file handle
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/
void __cdecl _lock_fhandle (
int fh
)
{
ioinfo *pio = _pioinfo(fh);
/*
* Make sure the lock has been initialized.
*/
if ( pio->lockinitflag == 0 ) {
_mlock( _LOCKTAB_LOCK );
if ( pio->lockinitflag == 0 ) {
InitializeCriticalSection( &(pio->lock) );
pio->lockinitflag++;
}
_munlock( _LOCKTAB_LOCK);
}
EnterCriticalSection( &(_pioinfo(fh)->lock) );
}
/***
*void _unlock_fhandle(int fh) - unlock file handle
*
*Purpose:
* Release the lock associated with passed file handle.
*
*Entry:
* int fh - CRT file handle
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/
void __cdecl _unlock_fhandle (
int fh
)
{
LeaveCriticalSection( &(_pioinfo(fh)->lock) );
}
#endif /* _MT */
#else /* _MAC */
#include <cruntime.h>
#include <errno.h>
#include <internal.h>
#include <fcntl.h>
#include <msdos.h>
#include <stdlib.h>
/***
*int _alloc_osfhnd() - get free _osfhnd[] entry
*
*Purpose:
* Finds the first free entry in _osfhnd[], mark it in use and return
* the index of the entry to the caller.
*
*Entry:
* none
*
*Exit:
* returns index of entry in fh, if successful
* return -1, if no free entry is found in _osfhnd[].
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _alloc_osfhnd(
void
)
{
int fh; /* _osfhnd[] index */
/*
* search _osfhnd[] for an entry that is not currently being used.
* if one is found, mark it in use and set the _osfhandle field to
* 0xffffffff.
*/
for ( fh = 0 ; fh < _nfile ; fh++ ) {
if ( (_osfile[fh] & FOPEN) == 0 ) {
/*
* free entry found! initialize it and
* break out of the loop
*/
_osfhnd[fh] = (long)0xffffffff;
break;
}
}
/*
* return the index of the previously free table entry, if one was
* found. return -1 otherwise.
*/
return( (fh >= _nfile) ? -1 : fh );
}
/***
*int _set_osfhnd(int fh) - set OS file handle table value
*
*Purpose:
* If fh is in range and if _osfhnd[fh] is marked with 0xfffffff
* then set _osfhnd[fh] to the passed value.
*
*Entry:
* int fh - index of _osfhnd[] entry
* long fh - new value of this handle entry
*
*Exit:
* Returns zero if successful.
* Returns -1 and sets errno to EBADF otherwise.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _set_osfhnd (
int fh, /* index into _osfhnd[] (user's file handle) */
long value
)
{
if ( ((unsigned)fh < (unsigned)_nfile) &&
_osfhnd[fh] == (long)0xffffffff
) {
_osfhnd[fh] = value;
return(0);
} else {
errno = EBADF; /* bad handle */
_macerrno = 0L; /* not an OS error */
return -1;
}
}
/***
*int _free_osfhnd(int fh) - free OS file handle table entry
*
*Purpose:
* If fh is in range and if _osfhnd[fh] is in use and NOT marked
* with 0xfffffff
*
*Entry:
* int fh - index of _osfhnd[] entry
*
*Exit:
* Returns zero if successful.
* Returns -1 and sets errno to EBADF otherwise.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _free_osfhnd (
int fh /* index into _osfhnd[] (user's file handle) */
)
{
if ( ((unsigned)fh < (unsigned)_nfile) &&
(_osfile[fh] & FOPEN) &&
_osfhnd[fh] != (long)0xffffffff
) {
_osfhnd[fh] = (long)0xffffffff;
return(0);
} else {
errno = EBADF; /* bad handle */
_macerrno = 0L; /* not an OS error */
return -1;
}
}
/***
*long _get_osfhandle(int fh) - get OS file handle
*
*Purpose:
* If fh is in range and if _osfhnd[fh] is marked free, return
* _osfhnd[fh]
*
*Entry:
* int fh - index of _osfhnd[] entry
*
*Exit:
* Returns the OS file handle if successful.
* Returns -1 and sets errno to EBADF otherwise.
*
*Exceptions:
*
*******************************************************************************/
long __cdecl _get_osfhandle (
int fh /* index into _osfhnd[] (user's file handle) */
)
{
if ( ((unsigned)fh < (unsigned)_nfile) && (_osfile[fh] & FOPEN))
return(_osfhnd[fh]);
else {
errno = EBADF; /* bad handle */
_macerrno = 0L; /* not an OS error */
return -1;
}
}
/***
*int _open_osfhandle(long osfhandle, int flags) - open C Runtime file handle
*
*Purpose:
* This function allocates a free C Runtime file handle and sets it
* to point to the Win32 file handle specified by the first parameter.
*
*Entry:
* long osfhandle -Win32 file handle to associate with C Runtime file handle.
* int flags - flags to associate with C Runtime file handle.
*
*Exit:
* returns index of entry in fh, if successful
* return -1, if no free entry is found in _osfhnd[].
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _open_osfhandle(
long osfhandle,
int flags
)
{
int fh;
char fileflags; /* _osfile flags */
/* copy relavent flags from second parameter */
fileflags = 0;
if ( flags & _O_RDONLY )
fileflags |= FRDONLY;
else if ( flags & _O_APPEND )
fileflags |= FAPPEND;
else if ( flags & _O_TEXT )
fileflags |= FTEXT;
/* attempt to allocate a C Runtime file handle */
if ( (fh = _alloc_osfhnd()) == -1 ) {
errno = EMFILE; /* too many open files */
_macerrno = 0L; /* not an OS error */
return -1; /* return error to caller */
}
/*
* the file is open. now, set the info in _osfhnd array
*/
_set_osfhnd(fh, osfhandle);
fileflags |= FOPEN; /* mark as open */
_osfile[fh] = fileflags; /* set osfile entry */
return fh; /* return handle */
}
#endif /* _MAC */