154 lines
3.5 KiB
C
154 lines
3.5 KiB
C
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/**************************************************************************
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* INT1.C
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*
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* Routines used to implement the interrupt trapping API in
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* TOOLHELP.DLL
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*
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**************************************************************************/
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#include <string.h>
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#include "toolpriv.h"
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/* ----- Global variables ----- */
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WORD wIntInstalled;
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INTERRUPT NEAR *npIntHead;
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/* InterruptRegister
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* Registers an interrupt callback.
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*/
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BOOL TOOLHELPAPI InterruptRegister(
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HANDLE hTask,
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FARPROC lpfnCallback)
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{
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INTERRUPT *pInt;
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INTERRUPT *pTemp;
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/* Make sure TOOLHELP.DLL is installed */
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if (!wLibInstalled)
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return FALSE;
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/* If the interrupt hook has not yet been installed, install it */
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if (!wIntInstalled)
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{
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/* Make sure we can hook! */
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if (!InterruptInit())
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return FALSE;
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wIntInstalled = TRUE;
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}
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/* NULL hTask means current task */
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if (!hTask)
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hTask = GetCurrentTask();
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/* Register a death signal handler for this task (does nothing if one
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* is already installed.
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*/
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SignalRegister(hTask);
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/* Check to see if this task is already registered */
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for (pInt = npIntHead ; pInt ; pInt = pInt->pNext)
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if (pInt->hTask == hTask)
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return FALSE;
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/* Allocate a new INTERRUPT structure */
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pInt = (INTERRUPT *)LocalAlloc(LMEM_FIXED, sizeof (INTERRUPT));
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if (!pInt)
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return FALSE;
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/* Fill in the useful fields */
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pInt->hTask = hTask;
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pInt->lpfn = (LPFNCALLBACK) lpfnCallback;
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/* If this is the only handler, just insert it */
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if (!npIntHead)
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{
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pInt->pNext = npIntHead;
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npIntHead = pInt;
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}
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/* Otherwise, insert at the end of the list */
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else
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{
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for (pTemp = npIntHead ; pTemp->pNext ; pTemp = pTemp->pNext)
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;
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pInt->pNext = pTemp->pNext;
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pTemp->pNext = pInt;
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}
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return TRUE;
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}
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/* InterruptUnRegister
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* Called by an app whose callback is no longer to be used.
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* NULL hTask uses current task.
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*/
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BOOL TOOLHELPAPI InterruptUnRegister(
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HANDLE hTask)
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{
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INTERRUPT *pInt;
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INTERRUPT *pBefore;
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/* Make sure we have interrupt installed and that TOOLHELP is OK */
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if (!wLibInstalled || !wIntInstalled)
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return FALSE;
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/* NULL hTask means current task */
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if (!hTask)
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hTask = GetCurrentTask();
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/* First try to find the task */
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pBefore = NULL;
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for (pInt = npIntHead ; pInt ; pInt = pInt->pNext)
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if (pInt->hTask == hTask)
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break;
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else
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pBefore = pInt;
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if (!pInt)
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return FALSE;
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/* Unhook the death signal proc only if there is no interrupt handler */
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if (!NotifyIsHooked(hTask))
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SignalUnRegister(hTask);
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/* Remove it from the list */
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if (!pBefore)
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npIntHead = pInt->pNext;
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else
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pBefore->pNext = pInt->pNext;
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/* Free the structure */
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LocalFree((HANDLE)pInt);
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/* If there are no more handlers, unhook the callback */
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if (!npIntHead)
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{
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InterruptUnInit();
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wIntInstalled = FALSE;
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}
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return TRUE;
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}
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/* ----- Helper functions ----- */
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/* InterruptIsHooked
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* Returns TRUE iff the parameter task already has a interrupt hook.
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*/
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BOOL PASCAL InterruptIsHooked(
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HANDLE hTask)
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{
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INTERRUPT *pInt;
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/* Loop thorugh all interrupts */
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for (pInt = npIntHead ; pInt ; pInt = pInt->pNext)
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if (pInt->hTask == hTask)
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break;
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/* Return found/not found */
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return (BOOL)pInt;
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}
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