519 lines
13 KiB
C
519 lines
13 KiB
C
/*
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* tclUnixNotify.c --
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*
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* This file contains the implementation of the select-based
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* Unix-specific notifier, which is the lowest-level part of the
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* Tcl event loop. This file works together with
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* ../generic/tclNotify.c.
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*
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* Copyright (c) 1995-1997 Sun Microsystems, Inc.
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*
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* See the file "license.terms" for information on usage and redistribution
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* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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*
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* SCCS: @(#) tclUnixNotfy.c 1.44 97/11/05 13:02:20
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*/
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#include "tclInt.h"
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#include "tclPort.h"
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#include <signal.h>
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/*
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* This structure is used to keep track of the notifier info for a
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* a registered file.
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*/
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typedef struct FileHandler {
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int fd;
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int mask; /* Mask of desired events: TCL_READABLE,
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* etc. */
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int readyMask; /* Mask of events that have been seen since the
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* last time file handlers were invoked for
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* this file. */
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Tcl_FileProc *proc; /* Procedure to call, in the style of
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* Tcl_CreateFileHandler. */
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ClientData clientData; /* Argument to pass to proc. */
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struct FileHandler *nextPtr;/* Next in list of all files we care about. */
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} FileHandler;
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/*
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* The following structure is what is added to the Tcl event queue when
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* file handlers are ready to fire.
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*/
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typedef struct FileHandlerEvent {
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Tcl_Event header; /* Information that is standard for
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* all events. */
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int fd; /* File descriptor that is ready. Used
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* to find the FileHandler structure for
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* the file (can't point directly to the
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* FileHandler structure because it could
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* go away while the event is queued). */
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} FileHandlerEvent;
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/*
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* The following static structure contains the state information for the
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* select based implementation of the Tcl notifier.
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*/
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static struct {
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FileHandler *firstFileHandlerPtr;
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/* Pointer to head of file handler list. */
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fd_mask checkMasks[3*MASK_SIZE];
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/* This array is used to build up the masks
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* to be used in the next call to select.
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* Bits are set in response to calls to
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* Tcl_CreateFileHandler. */
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fd_mask readyMasks[3*MASK_SIZE];
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/* This array reflects the readable/writable
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* conditions that were found to exist by the
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* last call to select. */
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int numFdBits; /* Number of valid bits in checkMasks
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* (one more than highest fd for which
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* Tcl_WatchFile has been called). */
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} notifier;
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/*
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* The following static indicates whether this module has been initialized.
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*/
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static int initialized = 0;
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/*
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* Static routines defined in this file.
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*/
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static void InitNotifier _ANSI_ARGS_((void));
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static void NotifierExitHandler _ANSI_ARGS_((
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ClientData clientData));
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static int FileHandlerEventProc _ANSI_ARGS_((Tcl_Event *evPtr,
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int flags));
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/*
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*----------------------------------------------------------------------
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*
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* InitNotifier --
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*
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* Initializes the notifier state.
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*
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* Results:
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* None.
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*
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* Side effects:
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* Creates a new exit handler.
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*
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*----------------------------------------------------------------------
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*/
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static void
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InitNotifier()
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{
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initialized = 1;
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memset(¬ifier, 0, sizeof(notifier));
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Tcl_CreateExitHandler(NotifierExitHandler, NULL);
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}
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/*
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*----------------------------------------------------------------------
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*
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* NotifierExitHandler --
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*
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* This function is called to cleanup the notifier state before
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* Tcl is unloaded.
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*
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* Results:
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* None.
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*
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* Side effects:
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* Destroys the notifier window.
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*
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*----------------------------------------------------------------------
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*/
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static void
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NotifierExitHandler(clientData)
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ClientData clientData; /* Not used. */
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{
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initialized = 0;
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}
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/*
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*----------------------------------------------------------------------
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*
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* Tcl_SetTimer --
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*
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* This procedure sets the current notifier timer value. This
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* interface is not implemented in this notifier because we are
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* always running inside of Tcl_DoOneEvent.
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*
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* Results:
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* None.
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*
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* Side effects:
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* None.
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*
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*----------------------------------------------------------------------
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*/
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void
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Tcl_SetTimer(timePtr)
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Tcl_Time *timePtr; /* Timeout value, may be NULL. */
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{
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/*
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* The interval timer doesn't do anything in this implementation,
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* because the only event loop is via Tcl_DoOneEvent, which passes
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* timeout values to Tcl_WaitForEvent.
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*/
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}
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/*
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*----------------------------------------------------------------------
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*
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* Tcl_CreateFileHandler --
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*
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* This procedure registers a file handler with the Xt notifier.
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*
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* Results:
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* None.
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*
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* Side effects:
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* Creates a new file handler structure and registers one or more
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* input procedures with Xt.
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*
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*----------------------------------------------------------------------
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*/
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void
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Tcl_CreateFileHandler(fd, mask, proc, clientData)
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int fd; /* Handle of stream to watch. */
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int mask; /* OR'ed combination of TCL_READABLE,
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* TCL_WRITABLE, and TCL_EXCEPTION:
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* indicates conditions under which
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* proc should be called. */
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Tcl_FileProc *proc; /* Procedure to call for each
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* selected event. */
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ClientData clientData; /* Arbitrary data to pass to proc. */
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{
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FileHandler *filePtr;
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int index, bit;
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if (!initialized) {
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InitNotifier();
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}
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for (filePtr = notifier.firstFileHandlerPtr; filePtr != NULL;
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filePtr = filePtr->nextPtr) {
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if (filePtr->fd == fd) {
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break;
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}
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}
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if (filePtr == NULL) {
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filePtr = (FileHandler*) ckalloc(sizeof(FileHandler)); /* MLK */
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filePtr->fd = fd;
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filePtr->readyMask = 0;
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filePtr->nextPtr = notifier.firstFileHandlerPtr;
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notifier.firstFileHandlerPtr = filePtr;
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}
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filePtr->proc = proc;
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filePtr->clientData = clientData;
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filePtr->mask = mask;
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/*
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* Update the check masks for this file.
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*/
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index = fd/(NBBY*sizeof(fd_mask));
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bit = 1 << (fd%(NBBY*sizeof(fd_mask)));
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if (mask & TCL_READABLE) {
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notifier.checkMasks[index] |= bit;
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} else {
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notifier.checkMasks[index] &= ~bit;
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}
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if (mask & TCL_WRITABLE) {
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(notifier.checkMasks+MASK_SIZE)[index] |= bit;
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} else {
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(notifier.checkMasks+MASK_SIZE)[index] &= ~bit;
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}
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if (mask & TCL_EXCEPTION) {
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(notifier.checkMasks+2*(MASK_SIZE))[index] |= bit;
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} else {
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(notifier.checkMasks+2*(MASK_SIZE))[index] &= ~bit;
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}
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if (notifier.numFdBits <= fd) {
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notifier.numFdBits = fd+1;
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}
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}
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/*
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*----------------------------------------------------------------------
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*
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* Tcl_DeleteFileHandler --
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*
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* Cancel a previously-arranged callback arrangement for
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* a file.
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*
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* Results:
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* None.
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*
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* Side effects:
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* If a callback was previously registered on file, remove it.
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*
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*----------------------------------------------------------------------
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*/
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void
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Tcl_DeleteFileHandler(fd)
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int fd; /* Stream id for which to remove callback procedure. */
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{
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FileHandler *filePtr, *prevPtr;
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int index, bit, i;
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unsigned long flags;
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if (!initialized) {
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InitNotifier();
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}
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/*
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* Find the entry for the given file (and return if there
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* isn't one).
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*/
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for (prevPtr = NULL, filePtr = notifier.firstFileHandlerPtr; ;
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prevPtr = filePtr, filePtr = filePtr->nextPtr) {
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if (filePtr == NULL) {
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return;
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}
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if (filePtr->fd == fd) {
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break;
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}
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}
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/*
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* Update the check masks for this file.
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*/
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index = fd/(NBBY*sizeof(fd_mask));
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bit = 1 << (fd%(NBBY*sizeof(fd_mask)));
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if (filePtr->mask & TCL_READABLE) {
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notifier.checkMasks[index] &= ~bit;
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}
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if (filePtr->mask & TCL_WRITABLE) {
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(notifier.checkMasks+MASK_SIZE)[index] &= ~bit;
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}
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if (filePtr->mask & TCL_EXCEPTION) {
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(notifier.checkMasks+2*(MASK_SIZE))[index] &= ~bit;
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}
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/*
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* Find current max fd.
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*/
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if (fd+1 == notifier.numFdBits) {
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for (notifier.numFdBits = 0; index >= 0; index--) {
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flags = notifier.checkMasks[index]
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| (notifier.checkMasks+MASK_SIZE)[index]
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| (notifier.checkMasks+2*(MASK_SIZE))[index];
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if (flags) {
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for (i = (NBBY*sizeof(fd_mask)); i > 0; i--) {
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if (flags & (((unsigned long)1) << (i-1))) {
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break;
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}
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}
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notifier.numFdBits = index * (NBBY*sizeof(fd_mask)) + i;
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break;
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}
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}
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}
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/*
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* Clean up information in the callback record.
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*/
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if (prevPtr == NULL) {
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notifier.firstFileHandlerPtr = filePtr->nextPtr;
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} else {
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prevPtr->nextPtr = filePtr->nextPtr;
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}
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ckfree((char *) filePtr);
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}
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/*
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*----------------------------------------------------------------------
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*
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* FileHandlerEventProc --
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*
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* This procedure is called by Tcl_ServiceEvent when a file event
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* reaches the front of the event queue. This procedure is
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* responsible for actually handling the event by invoking the
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* callback for the file handler.
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*
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* Results:
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* Returns 1 if the event was handled, meaning it should be removed
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* from the queue. Returns 0 if the event was not handled, meaning
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* it should stay on the queue. The only time the event isn't
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* handled is if the TCL_FILE_EVENTS flag bit isn't set.
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*
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* Side effects:
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* Whatever the file handler's callback procedure does.
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*
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*----------------------------------------------------------------------
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*/
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static int
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FileHandlerEventProc(evPtr, flags)
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Tcl_Event *evPtr; /* Event to service. */
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int flags; /* Flags that indicate what events to
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* handle, such as TCL_FILE_EVENTS. */
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{
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FileHandler *filePtr;
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FileHandlerEvent *fileEvPtr = (FileHandlerEvent *) evPtr;
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int mask;
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if (!(flags & TCL_FILE_EVENTS)) {
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return 0;
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}
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/*
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* Search through the file handlers to find the one whose handle matches
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* the event. We do this rather than keeping a pointer to the file
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* handler directly in the event, so that the handler can be deleted
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* while the event is queued without leaving a dangling pointer.
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*/
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for (filePtr = notifier.firstFileHandlerPtr; filePtr != NULL;
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filePtr = filePtr->nextPtr) {
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if (filePtr->fd != fileEvPtr->fd) {
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continue;
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}
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/*
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* The code is tricky for two reasons:
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* 1. The file handler's desired events could have changed
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* since the time when the event was queued, so AND the
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* ready mask with the desired mask.
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* 2. The file could have been closed and re-opened since
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* the time when the event was queued. This is why the
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* ready mask is stored in the file handler rather than
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* the queued event: it will be zeroed when a new
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* file handler is created for the newly opened file.
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*/
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mask = filePtr->readyMask & filePtr->mask;
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filePtr->readyMask = 0;
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if (mask != 0) {
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(*filePtr->proc)(filePtr->clientData, mask);
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}
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break;
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}
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return 1;
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}
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/*
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*----------------------------------------------------------------------
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*
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* Tcl_WaitForEvent --
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*
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* This function is called by Tcl_DoOneEvent to wait for new
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* events on the message queue. If the block time is 0, then
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* Tcl_WaitForEvent just polls without blocking.
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*
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* Results:
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* Returns -1 if the select would block forever, otherwise
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* returns 0.
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*
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* Side effects:
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* Queues file events that are detected by the select.
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*
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*----------------------------------------------------------------------
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*/
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int
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Tcl_WaitForEvent(timePtr)
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Tcl_Time *timePtr; /* Maximum block time, or NULL. */
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{
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FileHandler *filePtr;
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FileHandlerEvent *fileEvPtr;
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struct timeval timeout, *timeoutPtr;
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int bit, index, mask, numFound;
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if (!initialized) {
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InitNotifier();
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}
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/*
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* Set up the timeout structure. Note that if there are no events to
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* check for, we return with a negative result rather than blocking
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* forever.
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*/
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if (timePtr) {
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timeout.tv_sec = timePtr->sec;
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timeout.tv_usec = timePtr->usec;
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timeoutPtr = &timeout;
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} else if (notifier.numFdBits == 0) {
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return -1;
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} else {
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timeoutPtr = NULL;
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}
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memcpy((VOID *) notifier.readyMasks, (VOID *) notifier.checkMasks,
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3*MASK_SIZE*sizeof(fd_mask));
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numFound = select(notifier.numFdBits,
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(SELECT_MASK *) ¬ifier.readyMasks[0],
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(SELECT_MASK *) ¬ifier.readyMasks[MASK_SIZE],
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(SELECT_MASK *) ¬ifier.readyMasks[2*MASK_SIZE], timeoutPtr);
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/*
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* Some systems don't clear the masks after an error, so
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* we have to do it here.
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*/
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if (numFound == -1) {
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memset((VOID *) notifier.readyMasks, 0, 3*MASK_SIZE*sizeof(fd_mask));
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}
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/*
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* Queue all detected file events before returning.
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*/
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for (filePtr = notifier.firstFileHandlerPtr;
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(filePtr != NULL) && (numFound > 0);
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filePtr = filePtr->nextPtr) {
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index = filePtr->fd / (NBBY*sizeof(fd_mask));
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bit = 1 << (filePtr->fd % (NBBY*sizeof(fd_mask)));
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mask = 0;
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if (notifier.readyMasks[index] & bit) {
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mask |= TCL_READABLE;
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}
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if ((notifier.readyMasks+MASK_SIZE)[index] & bit) {
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mask |= TCL_WRITABLE;
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}
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if ((notifier.readyMasks+2*(MASK_SIZE))[index] & bit) {
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mask |= TCL_EXCEPTION;
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}
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if (!mask) {
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continue;
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} else {
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numFound--;
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}
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/*
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* Don't bother to queue an event if the mask was previously
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* non-zero since an event must still be on the queue.
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*/
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if (filePtr->readyMask == 0) {
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fileEvPtr = (FileHandlerEvent *) ckalloc(
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sizeof(FileHandlerEvent));
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fileEvPtr->header.proc = FileHandlerEventProc;
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fileEvPtr->fd = filePtr->fd;
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Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL);
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}
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filePtr->readyMask = mask;
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}
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return 0;
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}
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