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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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dospawn.c
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C/C++ Source or Header
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1998-06-17
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7KB
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225 lines
/***
*dospawn.c - spawn a child process
*
* Copyright (c) 1989-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _dospawn - spawn a child process
*
*******************************************************************************/
#include <cruntime.h>
#include <oscalls.h>
#include <internal.h>
#include <msdos.h>
#include <process.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <tchar.h>
#include <dbgint.h>
#ifndef WPRFLAG
int _p_overlay = 2;
#endif /* WPRFLAG */
/***
*int _dospawn(mode, name, cmdblk, envblk) - spawn a child process
*
*Purpose:
* Spawns a child process
*
*Entry:
* int mode - _P_WAIT, _P_NOWAIT, _P_NOWAITO, _P_OVERLAY, or _P_DETACH
* _TSCHAR *name - name of program to execute
* _TSCHAR *cmdblk - parameter block
* _TSCHAR *envblk - environment block
*
*Exit:
* _P_OVERLAY: -1 = error, otherwise doesn't return
* _P_WAIT: termination code << 8 + result code
* _P_DETACH: -1 = error, 0 = success
* others: PID of process
*
*Exceptions:
*
*******************************************************************************/
#ifdef WPRFLAG
int __cdecl _wdospawn (
#else /* WPRFLAG */
int __cdecl _dospawn (
#endif /* WPRFLAG */
int mode,
const _TSCHAR *name,
_TSCHAR *cmdblk,
_TSCHAR *envblk
)
{
char syncexec, asyncresult, background;
LPTSTR CommandLine;
STARTUPINFO StartupInfo;
PROCESS_INFORMATION ProcessInformation;
BOOL CreateProcessStatus;
ULONG dosretval; /* OS return value */
DWORD retval;
DWORD fdwCreate = 0; /* flags for CreateProcess */
int i;
ioinfo *pio;
char *posfile;
UNALIGNED long *posfhnd;
int nh; /* number of file handles to be
passed to the child */
/* translate input mode value to individual flags */
syncexec = asyncresult = background = 0;
switch (mode) {
case _P_WAIT: syncexec=1; break; /* synchronous execution */
case 2: /* _P_OVERLAY */
case _P_NOWAITO: break; /* asynchronous execution */
case _P_NOWAIT: asyncresult=1; break; /* asynch + remember result */
case _P_DETACH: background=1; break; /* detached in null scrn grp */
default:
/* invalid mode */
errno = EINVAL;
_doserrno = 0; /* not a Dos error */
return -1;
}
/*
* Loop over null separate arguments, and replace null separators
* with spaces to turn it back into a single null terminated
* command line.
*/
CommandLine = cmdblk;
while (*cmdblk) {
while (*cmdblk) {
cmdblk++;
}
/*
* If not last argument, turn null separator into a space.
*/
if (cmdblk[1] != _T('\0')) {
*cmdblk++ = _T(' ');
}
}
memset(&StartupInfo,0,sizeof(StartupInfo));
StartupInfo.cb = sizeof(StartupInfo);
for ( nh = _nhandle ;
nh && !_osfile(nh - 1) ;
nh-- ) ;
StartupInfo.cbReserved2 = (WORD)(sizeof( int ) + (nh *
(sizeof( char ) + sizeof( long ))));
StartupInfo.lpReserved2 = _calloc_crt( StartupInfo.cbReserved2, 1 );
*((UNALIGNED int *)(StartupInfo.lpReserved2)) = nh;
posfile = (char *)(StartupInfo.lpReserved2 + sizeof( int ));
posfhnd = (UNALIGNED long *)(StartupInfo.lpReserved2 + sizeof( int ) +
(nh * sizeof( char )));
for ( i = 0,
posfile = (char *)(StartupInfo.lpReserved2 + sizeof( int )),
posfhnd = (UNALIGNED long *)(StartupInfo.lpReserved2 +
sizeof( int ) + (nh * sizeof( char ))) ;
i < nh ;
i++, posfile++, posfhnd++ )
{
pio = _pioinfo(i);
if ( (pio->osfile & FNOINHERIT) == 0 ) {
*posfile = pio->osfile;
*posfhnd = pio->osfhnd;
}
else {
*posfile = 0;
*posfhnd = (long)INVALID_HANDLE_VALUE;
}
}
/*
* if the child process is detached, it cannot access the console, so
* we must nuke the information passed for the first three handles.
*/
if ( background ) {
for ( i = 0,
posfile = (char *)(StartupInfo.lpReserved2 + sizeof( int )),
posfhnd = (UNALIGNED long *)(StartupInfo.lpReserved2 + sizeof( int )
+ (nh * sizeof( char ))) ;
i < __min( nh, 3 ) ;
i++, posfile++, posfhnd++ )
{
*posfile = 0;
*posfhnd = (long)INVALID_HANDLE_VALUE;
}
fdwCreate |= DETACHED_PROCESS;
}
/**
* Set errno to 0 to distinguish a child process
* which returns -1L from an error in the spawning
* (which will set errno to something non-zero
**/
_doserrno = errno = 0 ;
#ifdef WPRFLAG
/* indicate to CreateProcess that environment block is wide */
fdwCreate |= CREATE_UNICODE_ENVIRONMENT;
#endif /* WPRFLAG */
CreateProcessStatus = CreateProcess( (LPTSTR)name,
CommandLine,
NULL,
NULL,
TRUE,
fdwCreate,
envblk,
NULL,
&StartupInfo,
&ProcessInformation
);
dosretval = GetLastError();
_free_crt( StartupInfo.lpReserved2 );
if (!CreateProcessStatus) {
_dosmaperr(dosretval);
return -1;
}
if (mode == 2 /* _P_OVERLAY */) {
/* destroy ourselves */
_exit(0);
}
else if (mode == _P_WAIT) {
WaitForSingleObject(ProcessInformation.hProcess, (DWORD)(-1L));
/* return termination code and exit code -- note we return
the full exit code */
GetExitCodeProcess(ProcessInformation.hProcess, &retval);
CloseHandle(ProcessInformation.hProcess);
}
else if (mode == _P_DETACH) {
/* like totally detached asynchronous spawn, dude,
close process handle, return 0 for success */
CloseHandle(ProcessInformation.hProcess);
retval = (DWORD)0;
}
else {
/* asynchronous spawn -- return PID */
retval = (DWORD)ProcessInformation.hProcess;
}
CloseHandle(ProcessInformation.hThread);
return retval;
}