[Q]: wait/cwait ­¥ y¬¥¥â p ¡®â âì á á¥áá¨ï¬¨

[A]: Unknown author

This small program will start any program synchronously using
DosStartSession(). The important thing is the queue. When you specify
SSF_RELATED_CHILD and a TermQ name, OS/2 will write the return code to the
specified queue when the session terminates. I use this in an event
scheduler by creating a separate thread that does reads from the queue but
you can just as easily block on the main thread to catch the return code.
That will, in effect, provide for synchronous execution. Note that one
problem with SSF_RELATED_CHILD is that if the program that started the
child dies, so does the child.

#define INCL_DOSERRORS
#define INCL_DOSPROCESS
#define INCL_DOSQUEUES
#define INCL_DOSSESMGR
#include <os2.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define QUEUE_NAME "\\QUEUES\\STRTSYNC.QUE"

int main( int argc, char *argv[] );

int main( int argc, char *argv[] )
{
APIRET rc;
HQUEUE hque;

if( argc < 2 )
return 1;

rc = DosCreateQueue( &hque, QUE_FIFO | QUE_CONVERT_ADDRESS, QUEUE_NAME );
if( !rc )
{
STARTDATA stdata;
PID pidSession;
CHAR szObjFail[ 50 ];
ULONG ulLength, idSession;
REQUESTDATA rd;
PUSHORT pusInfo = NULL;
BYTE bPriority;

(void) memset( &stdata, 0, sizeof( stdata ) );

stdata.Length = sizeof( STARTDATA );
stdata.FgBg = SSF_FGBG_FORE;
stdata.TraceOpt = SSF_TRACEOPT_NONE;
stdata.PgmTitle = "Rick's Program";
stdata.InheritOpt = SSF_INHERTOPT_SHELL;
stdata.SessionType = SSF_TYPE_DEFAULT;
stdata.PgmControl = SSF_CONTROL_VISIBLE;
stdata.ObjectBuffer = szObjFail;
stdata.ObjectBuffLen= sizeof( szObjFail );
stdata.Related = SSF_RELATED_CHILD;
stdata.TermQ = QUEUE_NAME;
stdata.PgmName = argv[ 1 ];

rc = DosStartSession( &stdata, &idSession, &pidSession );

if( rc && rc != ERROR_SMG_START_IN_BACKGROUND )
{
printf( "DosStartSession RC(%u)\n", rc );
return (INT) rc;
}

rc = DosReadQueue( hque, &rd, &ulLength, (PPVOID) &pusInfo, 0,
DCWW_WAIT, &bPriority, 0 );

if( rc && rc != ERROR_QUE_EMPTY )
{
printf( "DosReadQueue RC(%u)\n", rc );
return (INT) rc;
}

printf( "RetCode from Session %u: %u\n",
pusInfo[ 0 ], pusInfo[ 1 ]);

DosCloseQueue( hque );
}
else
{
printf( "DosCreateQueue RC(%u)\n", rc );
return (INT) rc;
}

return 0;
}

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