wait.c

C标准库源代码

/***
*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;
}