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Tricks of the Windows Gam…ming Gurus (2nd Edition)
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vc98
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crt
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wait.c
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1998-06-17
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/***
*wait.c - wait for child process to terminate
*
* Copyright (c) 1989-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _wait() - wait for child process to terminate
*
*******************************************************************************/
#include <cruntime.h>
#include <oscalls.h>
#include <process.h>
#include <errno.h>
#include <internal.h>
#include <stdlib.h>
/***
*int _cwait(stat_loc, process_id, action_code) - wait for specific child
* process
*
*Purpose:
* The function _cwait() suspends the calling-process until the specified
* child-process terminates. If the specifed child-process terminated
* prior to the call to _cwait(), return is immediate.
*
*Entry:
* int *stat_loc - pointer to where status is stored or NULL
* process_id - specific process id to be interrogated (0 means any)
* action_code - specific action to perform on process ID
* either _WAIT_CHILD or _WAIT_GRANDCHILD
*
*Exit:
* process ID of terminated child or -1 on error
*
* *stat_loc is updated to contain the following:
* Normal termination: lo-byte = 0, hi-byte = child exit code
* Abnormal termination: lo-byte = term status, hi-byte = 0
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _cwait (
int *stat_loc,
int process_id,
int action_code
)
{
int retval;
int retstatus;
unsigned long oserror;
DBG_UNREFERENCED_PARAMETER(action_code);
/* Explicitly check for process_id being -1 or -2. In Windows NT,
* -1 is a handle on the current process, -2 is a handle on the
* current thread, and it is perfectly legal to to wait (forever)
* on either */
if ( (process_id == -1) || (process_id == -2) ) {
errno = ECHILD;
return -1;
}
/* wait for child process, then fetch its exit code */
if ( (WaitForSingleObject((HANDLE)process_id, (DWORD)(-1L)) == 0) &&
GetExitCodeProcess((HANDLE)process_id, (LPDWORD)&retstatus) ) {
retval = process_id;
}
else {
/* one of the API calls failed. map the error and set up to
return failure. note the invalid handle error is mapped in-
line to ECHILD */
if ( (oserror = GetLastError()) == ERROR_INVALID_HANDLE ) {
errno = ECHILD;
_doserrno = oserror;
}
else
_dosmaperr(GetLastError());
retval = -1;
retstatus = -1;
}
CloseHandle((HANDLE)process_id);
if (stat_loc != NULL)
*stat_loc = retstatus;
return retval;
}