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Microsoft OS/2 SDK 03-01-1988

/*
 * Example of DosCWait usage.
 *
 * Although a process can only call DosCWait on its own child processes,
 * it is possible to wait indirectly on subsequent generations of
 * processes by use of the ProcessAndDescendents flag.  To wait for a
 * collection of subprocesses to end, a process must call DosCWait
 * repeatedly, once for each of the subprocesses.  The result codes
 * field is only valid for the one call first call against the child.
 * Subsequent calls indicate that another descendent process has ended,
 * but do not return exit or termination codes.
 * 
 * To wait for any child, rather that a specific one, the process
 * should pass in a process id of 0.  The pid of the process that ended
 * will be placed in the ProcessIdWord field.
 *
 * Compile as: cl -AL -G2 -Lp cwait.c
 *
 * Created by Microsoft Corp. 1986
 */

#define INCL_DOSPROCESS

#include <os2def.h>
#include <bsedos.h>
#include <stdio.h>

#define ERRBUF_LEN	64
#define ARG_LEN		128

main()
{
	RESULTCODES child_status, child_pid;
	PID ending_pid;
	unsigned res;
	char errbuf[ERRBUF_LEN];
	char child_arg[ARG_LEN];
	char *child_env;

	/*
	 * Execute a program and wait for it to finish.
	 */
	DosExecPgm((char *)0, 0, 2, (char *)0, (char *)0, &child_pid,
		"child.exe");
	printf("exec'd child, pid = %u\n", child_pid);
	DosCWait(0,0, &child_status, &ending_pid, child_pid.codeTerminate);
	if (child_status.codeTerminate != 0)
		printf("error: child's termination code was %u\n",
			child_status.codeTerminate);
	else
		printf("child process returned %u\n", child_status.codeResult);

	/*
	 * Execute a program and wait for it and all of its descendents
	 * to finish. In this case we specify the top pid to wait for.
	 */
	DosExecPgm((char *)0, 0, 2, (char *)0, (char *)0, &child_pid,
		"child.exe");
	printf("exec'd child, pid = %u\n", child_pid);
	do {
		res = DosCWait(1,0, &child_status, &ending_pid,
			child_pid.codeTerminate);
		if(res == 0)
			printf("cwait found pid = %u\n", ending_pid);
		else
			printf("cwait found no more process\n");
	} while (res == 0);
	
	/*
	 * Wait for any child to terminate. In this case we specify
	 * the pid as zero, which means wait for any child to finish.
	 */
	DosExecPgm((char *)0, 0, 2, (char *)0, (char *)0, &child_pid,
		"child.exe");
	printf("exec'd child, pid = %u\n", child_pid);
	do {
		res = DosCWait(1,0, &child_status, &ending_pid, 0);
		if (res == 0)
			printf("child %u ended\n", ending_pid);
	} while (res == 0);
}

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