DosSetSignalExceptionFocus
Causes the current process to become the focus for the Ctrl+C and Ctrl+Break signals.
Syntax
DosSetSignalExceptionFocus(flag, pulTimes)
Parameters
- flag (BOOL32)
- Focus flag.
- pulTimes (PULONG)
- The number of times DosSetSignalExceptionFocus has been called by the current process with flag set to SIG_SETFOCUS, minus the number of times it has been called with flag set to SIG_UNSETFOCUS.
Return Code
- ulrc (APIRET) - returns
- DosSetSignalExceptionFocus returns one of the following values:
- 0 NO_ERROR
- 1 ERROR_INVALID_FUNCTION
- 300 ERROR_ALREADY_RESET
- 303 ERROR_INVALID_PROCID
- 650 ERROR_NESTING_TOO_DEEP
Remarks
Do not make Presentation Manager calls from exception handlers.
DosSetSignalExceptionFocus causes the calling process to become the signal focus for its screen group for the XCPT_SIGNAL_BREAK (Ctrl+Break) and XCPT_SIGNAL_INTR (Ctrl+C) signal exceptions.
You cannot issue DosSetSignalExceptionFocus from a Presentation Manager (PM) application. If you do, you get the return code ERROR_INVALID_PROCID. You can issue this function from a full-screen or windowed application.
Example Code
This example shows how to set the current thread to be the focus for the Ctrl+C and Ctrl+Break signals.
#define INCL_DOSPROCESS /* DOS process values (for DosSleep) */
#define INCL_DOSEXCEPTIONS /* DOS exception values */
#define INCL_ERRORS /* DOS error values */
#include <os2.h>
#include <stdio.h>
ULONG _System MyTermHandler( PEXCEPTIONREPORTRECORD p1,
PEXCEPTIONREGISTRATIONRECORD p2,
PCONTEXTRECORD p3,
PVOID pv );
int main (VOID)
{
EXCEPTIONREGISTRATIONRECORD RegRec = {0}; /* Exception Registration Record */
APIRET rc = NO_ERROR; /* Return code*/
/* Add MyTermHandler to this thread's chain of exception handlers */
RegRec.ExceptionHandler = (ERR)MyTermHandler;
rc = DosSetExceptionHandler( &RegRec );
if (rc != NO_ERROR) {
printf("DosSetExceptionHandler error: return code = %u\n",rc);
return 1;
}
printf("Terminate this program using Ctrl-C or Ctrl-Break.\n");
rc = DosSleep(60000L); /* Give user plenty of time to comply... */
rc = DosUnsetExceptionHandler( &RegRec );
if (rc != NO_ERROR) {
printf("DosUnsetExceptionHandler error: return code = %u\n",rc);
return 1;
}
return NO_ERROR;
}
/***************************************************************************/
ULONG _System MyTermHandler( PEXCEPTIONREPORTRECORD p1,
PEXCEPTIONREGISTRATIONRECORD p2,
PCONTEXTRECORD p3,
PVOID pv )
{
ULONG ulCount = 0; /* Count of API calls */
APIRET rc = NO_ERROR; /* Return code */
printf("*** MyTermHandler entered: ExceptionNum = %x\n",p1->ExceptionNum);
rc = DosSetSignalExceptionFocus( SIG_UNSETFOCUS, &ulCount);
if (rc != NO_ERROR) {
printf("DosSetSignalExceptionFocus error: return code = %u\n", rc);
return 1;
}
/**************************************/
/* Handle XCPT_SIGNAL exceptions here */
/**************************************/
rc = DosSetSignalExceptionFocus( SIG_SETFOCUS, &ulCount);
if (rc != NO_ERROR) {
printf("DosSetSignalExceptionFocus error: return code = %u\n", rc);
return 1;
}
return XCPT_CONTINUE_SEARCH; /* Exception not resolved... */
}