/* * tclEvent.c -- * * This file implements some general event related interfaces including * background errors, exit handlers, and the "vwait" and "update" * command procedures. * * Copyright (c) 1990-1994 The Regents of the University of California. * Copyright (c) 1994-1997 Sun Microsystems, Inc. * * See the file "license.terms" for information on usage and redistribution * of this file, and for a DISCLAIMER OF ALL WARRANTIES. * * RCS: @(#) $Id: tclEvent.c,v 1.2 2001/09/14 01:42:55 zlaski Exp $ */ #include "tclInt.h" #include "tclPort.h" /* * The data structure below is used to report background errors. One * such structure is allocated for each error; it holds information * about the interpreter and the error until bgerror can be invoked * later as an idle handler. */ typedef struct BgError { Tcl_Interp *interp; /* Interpreter in which error occurred. NULL * means this error report has been cancelled * (a previous report generated a break). */ char *errorMsg; /* The error message (interp->result when * the error occurred). Malloc-ed. */ char *errorInfo; /* Value of the errorInfo variable * (malloc-ed). */ char *errorCode; /* Value of the errorCode variable * (malloc-ed). */ struct BgError *nextPtr; /* Next in list of all pending error * reports for this interpreter, or NULL * for end of list. */ } BgError; /* * One of the structures below is associated with the "tclBgError" * assoc data for each interpreter. It keeps track of the head and * tail of the list of pending background errors for the interpreter. */ typedef struct ErrAssocData { BgError *firstBgPtr; /* First in list of all background errors * waiting to be processed for this * interpreter (NULL if none). */ BgError *lastBgPtr; /* Last in list of all background errors * waiting to be processed for this * interpreter (NULL if none). */ } ErrAssocData; /* * For each exit handler created with a call to Tcl_CreateExitHandler * there is a structure of the following type: */ typedef struct ExitHandler { Tcl_ExitProc *proc; /* Procedure to call when process exits. */ ClientData clientData; /* One word of information to pass to proc. */ struct ExitHandler *nextPtr;/* Next in list of all exit handlers for * this application, or NULL for end of list. */ } ExitHandler; static ExitHandler *firstExitPtr = NULL; /* First in list of all exit handlers for * application. */ /* * The following variable is a "secret" indication to Tcl_Exit that * it should dump out the state of memory before exiting. If the * value is non-NULL, it gives the name of the file in which to * dump memory usage information. */ char *tclMemDumpFileName = NULL; /* * This variable is set to 1 when Tcl_Exit is called, and at the end of * its work, it is reset to 0. The variable is checked by TclInExit() to * allow different behavior for exit-time processing, e.g. in closing of * files and pipes. */ static int tclInExit = 0; /* * Prototypes for procedures referenced only in this file: */ static void BgErrorDeleteProc _ANSI_ARGS_((ClientData clientData, Tcl_Interp *interp)); static void HandleBgErrors _ANSI_ARGS_((ClientData clientData)); static char * VwaitVarProc _ANSI_ARGS_((ClientData clientData, Tcl_Interp *interp, char *name1, char *name2, int flags)); /* *---------------------------------------------------------------------- * * Tcl_BackgroundError -- * * This procedure is invoked to handle errors that occur in Tcl * commands that are invoked in "background" (e.g. from event or * timer bindings). * * Results: * None. * * Side effects: * The command "bgerror" is invoked later as an idle handler to * process the error, passing it the error message. If that fails, * then an error message is output on stderr. * *---------------------------------------------------------------------- */ void Tcl_BackgroundError(interp) Tcl_Interp *interp; /* Interpreter in which an error has * occurred. */ { BgError *errPtr; char *errResult, *varValue; ErrAssocData *assocPtr; /* * The Tcl_AddErrorInfo call below (with an empty string) ensures that * errorInfo gets properly set. It's needed in cases where the error * came from a utility procedure like Tcl_GetVar instead of Tcl_Eval; * in these cases errorInfo still won't have been set when this * procedure is called. */ Tcl_AddErrorInfo(interp, ""); errResult = TclGetStringFromObj(Tcl_GetObjResult(interp), (int *) NULL); errPtr = (BgError *) ckalloc(sizeof(BgError)); errPtr->interp = interp; errPtr->errorMsg = (char *) ckalloc((unsigned) (strlen(errResult) + 1)); strcpy(errPtr->errorMsg, errResult); varValue = Tcl_GetVar(interp, "errorInfo", TCL_GLOBAL_ONLY); if (varValue == NULL) { varValue = errPtr->errorMsg; } errPtr->errorInfo = (char *) ckalloc((unsigned) (strlen(varValue) + 1)); strcpy(errPtr->errorInfo, varValue); varValue = Tcl_GetVar(interp, "errorCode", TCL_GLOBAL_ONLY); if (varValue == NULL) { varValue = ""; } errPtr->errorCode = (char *) ckalloc((unsigned) (strlen(varValue) + 1)); strcpy(errPtr->errorCode, varValue); errPtr->nextPtr = NULL; assocPtr = (ErrAssocData *) Tcl_GetAssocData(interp, "tclBgError", (Tcl_InterpDeleteProc **) NULL); if (assocPtr == NULL) { /* * This is the first time a background error has occurred in * this interpreter. Create associated data to keep track of * pending error reports. */ assocPtr = (ErrAssocData *) ckalloc(sizeof(ErrAssocData)); assocPtr->firstBgPtr = NULL; assocPtr->lastBgPtr = NULL; Tcl_SetAssocData(interp, "tclBgError", BgErrorDeleteProc, (ClientData) assocPtr); } if (assocPtr->firstBgPtr == NULL) { assocPtr->firstBgPtr = errPtr; Tcl_DoWhenIdle(HandleBgErrors, (ClientData) assocPtr); } else { assocPtr->lastBgPtr->nextPtr = errPtr; } assocPtr->lastBgPtr = errPtr; Tcl_ResetResult(interp); } /* *---------------------------------------------------------------------- * * HandleBgErrors -- * * This procedure is invoked as an idle handler to process all of * the accumulated background errors. * * Results: * None. * * Side effects: * Depends on what actions "bgerror" takes for the errors. * *---------------------------------------------------------------------- */ static void HandleBgErrors(clientData) ClientData clientData; /* Pointer to ErrAssocData structure. */ { Tcl_Interp *interp; char *command; char *argv[2]; int code; BgError *errPtr; ErrAssocData *assocPtr = (ErrAssocData *) clientData; Tcl_Channel errChannel; Tcl_Preserve((ClientData) assocPtr); while (assocPtr->firstBgPtr != NULL) { interp = assocPtr->firstBgPtr->interp; if (interp == NULL) { goto doneWithInterp; } /* * Restore important state variables to what they were at * the time the error occurred. */ Tcl_SetVar(interp, "errorInfo", assocPtr->firstBgPtr->errorInfo, TCL_GLOBAL_ONLY); Tcl_SetVar(interp, "errorCode", assocPtr->firstBgPtr->errorCode, TCL_GLOBAL_ONLY); /* * Create and invoke the bgerror command. */ argv[0] = "bgerror"; argv[1] = assocPtr->firstBgPtr->errorMsg; command = Tcl_Merge(2, argv); Tcl_AllowExceptions(interp); Tcl_Preserve((ClientData) interp); code = Tcl_GlobalEval(interp, command); ckfree(command); if (code == TCL_ERROR) { /* * If the interpreter is safe, we look for a hidden command * named "bgerror" and call that with the error information. * Otherwise, simply ignore the error. The rationale is that * this could be an error caused by a malicious applet trying * to cause an infinite barrage of error messages. The hidden * "bgerror" command can be used by a security policy to * interpose on such attacks and e.g. kill the applet after a * few attempts. */ if (Tcl_IsSafe(interp)) { Tcl_HashTable *hTblPtr; Tcl_HashEntry *hPtr; hTblPtr = (Tcl_HashTable *) Tcl_GetAssocData(interp, "tclHiddenCmds", NULL); if (hTblPtr == (Tcl_HashTable *) NULL) { goto doneWithInterp; } hPtr = Tcl_FindHashEntry(hTblPtr, "bgerror"); if (hPtr == (Tcl_HashEntry *) NULL) { goto doneWithInterp; } /* * OK, the hidden command "bgerror" exists, invoke it. */ argv[0] = "bgerror"; argv[1] = ckalloc((unsigned) strlen(assocPtr->firstBgPtr->errorMsg)); strcpy(argv[1], assocPtr->firstBgPtr->errorMsg); (void) TclInvoke(interp, 2, argv, TCL_INVOKE_HIDDEN); ckfree(argv[1]); goto doneWithInterp; } /* * We have to get the error output channel at the latest possible * time, because the eval (above) might have changed the channel. */ errChannel = Tcl_GetStdChannel(TCL_STDERR); if (errChannel != (Tcl_Channel) NULL) { if (strcmp(interp->result, "\"bgerror\" is an invalid command name or ambiguous abbreviation") == 0) { Tcl_Write(errChannel, assocPtr->firstBgPtr->errorInfo, -1); Tcl_Write(errChannel, "\n", -1); } else { Tcl_Write(errChannel, "bgerror failed to handle background error.\n", -1); Tcl_Write(errChannel, " Original error: ", -1); Tcl_Write(errChannel, assocPtr->firstBgPtr->errorMsg, -1); Tcl_Write(errChannel, "\n", -1); Tcl_Write(errChannel, " Error in bgerror: ", -1); Tcl_Write(errChannel, interp->result, -1); Tcl_Write(errChannel, "\n", -1); } Tcl_Flush(errChannel); } } else if (code == TCL_BREAK) { /* * Break means cancel any remaining error reports for this * interpreter. */ for (errPtr = assocPtr->firstBgPtr; errPtr != NULL; errPtr = errPtr->nextPtr) { if (errPtr->interp == interp) { errPtr->interp = NULL; } } } /* * Discard the command and the information about the error report. */ doneWithInterp: if (assocPtr->firstBgPtr) { ckfree(assocPtr->firstBgPtr->errorMsg); ckfree(assocPtr->firstBgPtr->errorInfo); ckfree(assocPtr->firstBgPtr->errorCode); errPtr = assocPtr->firstBgPtr->nextPtr; ckfree((char *) assocPtr->firstBgPtr); assocPtr->firstBgPtr = errPtr; } if (interp != NULL) { Tcl_Release((ClientData) interp); } } assocPtr->lastBgPtr = NULL; Tcl_Release((ClientData) assocPtr); } /* *---------------------------------------------------------------------- * * BgErrorDeleteProc -- * * This procedure is associated with the "tclBgError" assoc data * for an interpreter; it is invoked when the interpreter is * deleted in order to free the information assoicated with any * pending error reports. * * Results: * None. * * Side effects: * Background error information is freed: if there were any * pending error reports, they are cancelled. * *---------------------------------------------------------------------- */ static void BgErrorDeleteProc(clientData, interp) ClientData clientData; /* Pointer to ErrAssocData structure. */ Tcl_Interp *interp; /* Interpreter being deleted. */ { ErrAssocData *assocPtr = (ErrAssocData *) clientData; BgError *errPtr; while (assocPtr->firstBgPtr != NULL) { errPtr = assocPtr->firstBgPtr; assocPtr->firstBgPtr = errPtr->nextPtr; ckfree(errPtr->errorMsg); ckfree(errPtr->errorInfo); ckfree(errPtr->errorCode); ckfree((char *) errPtr); } Tcl_CancelIdleCall(HandleBgErrors, (ClientData) assocPtr); Tcl_EventuallyFree((ClientData) assocPtr, TCL_DYNAMIC); } /* *---------------------------------------------------------------------- * * Tcl_CreateExitHandler -- * * Arrange for a given procedure to be invoked just before the * application exits. * * Results: * None. * * Side effects: * Proc will be invoked with clientData as argument when the * application exits. * *---------------------------------------------------------------------- */ void Tcl_CreateExitHandler(proc, clientData) Tcl_ExitProc *proc; /* Procedure to invoke. */ ClientData clientData; /* Arbitrary value to pass to proc. */ { ExitHandler *exitPtr; exitPtr = (ExitHandler *) ckalloc(sizeof(ExitHandler)); exitPtr->proc = proc; exitPtr->clientData = clientData; exitPtr->nextPtr = firstExitPtr; firstExitPtr = exitPtr; } /* *---------------------------------------------------------------------- * * Tcl_DeleteExitHandler -- * * This procedure cancels an existing exit handler matching proc * and clientData, if such a handler exits. * * Results: * None. * * Side effects: * If there is an exit handler corresponding to proc and clientData * then it is cancelled; if no such handler exists then nothing * happens. * *---------------------------------------------------------------------- */ void Tcl_DeleteExitHandler(proc, clientData) Tcl_ExitProc *proc; /* Procedure that was previously registered. */ ClientData clientData; /* Arbitrary value to pass to proc. */ { ExitHandler *exitPtr, *prevPtr; for (prevPtr = NULL, exitPtr = firstExitPtr; exitPtr != NULL; prevPtr = exitPtr, exitPtr = exitPtr->nextPtr) { if ((exitPtr->proc == proc) && (exitPtr->clientData == clientData)) { if (prevPtr == NULL) { firstExitPtr = exitPtr->nextPtr; } else { prevPtr->nextPtr = exitPtr->nextPtr; } ckfree((char *) exitPtr); return; } } } /* *---------------------------------------------------------------------- * * Tcl_Exit -- * * This procedure is called to terminate the application. * * Results: * None. * * Side effects: * All existing exit handlers are invoked, then the application * ends. * *---------------------------------------------------------------------- */ void Tcl_Exit(status) int status; /* Exit status for application; typically * 0 for normal return, 1 for error return. */ { Tcl_Finalize(); #ifdef TCL_MEM_DEBUG if (tclMemDumpFileName != NULL) { Tcl_DumpActiveMemory(tclMemDumpFileName); } #endif TclPlatformExit(status); } /* *---------------------------------------------------------------------- * * Tcl_Finalize -- * * Runs the exit handlers to allow Tcl to clean up its state prior * to being unloaded. Called by Tcl_Exit and when Tcl was dynamically * loaded and is now being unloaded. * * Results: * None. * * Side effects: * Whatever the exit handlers do. Also frees up storage associated * with the Tcl object type table. * *---------------------------------------------------------------------- */ void Tcl_Finalize() { ExitHandler *exitPtr; /* * Invoke exit handler first. */ tclInExit = 1; for (exitPtr = firstExitPtr; exitPtr != NULL; exitPtr = firstExitPtr) { /* * Be careful to remove the handler from the list before invoking * its callback. This protects us against double-freeing if the * callback should call Tcl_DeleteExitHandler on itself. */ firstExitPtr = exitPtr->nextPtr; (*exitPtr->proc)(exitPtr->clientData); ckfree((char *) exitPtr); } /* * Now finalize the Tcl execution environment. Note that this must be done * after the exit handlers, because there are order dependencies. */ TclFinalizeCompExecEnv(); TclFinalizeEnvironment(); TclpFinalize(); firstExitPtr = NULL; tclInExit = 0; } /* *---------------------------------------------------------------------- * * TclInExit -- * * Determines if we are in the middle of exit-time cleanup. * * Results: * If we are in the middle of exiting, 1, otherwise 0. * * Side effects: * None. * *---------------------------------------------------------------------- */ int TclInExit() { return tclInExit; } /* *---------------------------------------------------------------------- * * Tcl_VwaitCmd -- * * This procedure is invoked to process the "vwait" Tcl command. * See the user documentation for details on what it does. * * Results: * A standard Tcl result. * * Side effects: * See the user documentation. * *---------------------------------------------------------------------- */ /* ARGSUSED */ int Tcl_VwaitCmd(clientData, interp, argc, argv) ClientData clientData; /* Not used. */ Tcl_Interp *interp; /* Current interpreter. */ int argc; /* Number of arguments. */ char **argv; /* Argument strings. */ { int done, foundEvent; if (argc != 2) { Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0], " name\"", (char *) NULL); return TCL_ERROR; } if (Tcl_TraceVar(interp, argv[1], TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS, VwaitVarProc, (ClientData) &done) != TCL_OK) { return TCL_ERROR; }; done = 0; foundEvent = 1; while (!done && foundEvent) { foundEvent = Tcl_DoOneEvent(TCL_ALL_EVENTS); } Tcl_UntraceVar(interp, argv[1], TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS, VwaitVarProc, (ClientData) &done); /* * Clear out the interpreter's result, since it may have been set * by event handlers. */ Tcl_ResetResult(interp); if (!foundEvent) { Tcl_AppendResult(interp, "can't wait for variable \"", argv[1], "\": would wait forever", (char *) NULL); return TCL_ERROR; } return TCL_OK; } /* ARGSUSED */ static char * VwaitVarProc(clientData, interp, name1, name2, flags) ClientData clientData; /* Pointer to integer to set to 1. */ Tcl_Interp *interp; /* Interpreter containing variable. */ char *name1; /* Name of variable. */ char *name2; /* Second part of variable name. */ int flags; /* Information about what happened. */ { int *donePtr = (int *) clientData; *donePtr = 1; return (char *) NULL; } /* *---------------------------------------------------------------------- * * Tcl_UpdateCmd -- * * This procedure is invoked to process the "update" Tcl command. * See the user documentation for details on what it does. * * Results: * A standard Tcl result. * * Side effects: * See the user documentation. * *---------------------------------------------------------------------- */ /* ARGSUSED */ int Tcl_UpdateCmd(clientData, interp, argc, argv) ClientData clientData; /* Not used. */ Tcl_Interp *interp; /* Current interpreter. */ int argc; /* Number of arguments. */ char **argv; /* Argument strings. */ { int flags; if (argc == 1) { flags = TCL_ALL_EVENTS|TCL_DONT_WAIT; } else if (argc == 2) { if (strncmp(argv[1], "idletasks", strlen(argv[1])) != 0) { Tcl_AppendResult(interp, "bad option \"", argv[1], "\": must be idletasks", (char *) NULL); return TCL_ERROR; } flags = TCL_WINDOW_EVENTS|TCL_IDLE_EVENTS|TCL_DONT_WAIT; } else { Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0], " ?idletasks?\"", (char *) NULL); return TCL_ERROR; } while (Tcl_DoOneEvent(flags) != 0) { /* Empty loop body */ } /* * Must clear the interpreter's result because event handlers could * have executed commands. */ Tcl_ResetResult(interp); return TCL_OK; }