/*
* tclUnixNotify.c --
*
* This file contains the implementation of the select-based
* Unix-specific notifier, which is the lowest-level part of the
* Tcl event loop. This file works together with
* ../generic/tclNotify.c.
*
* Copyright (c) 1995-1997 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: tclUnixNotfy.c,v 1.2 1998/09/14 18:40:17 stanton Exp $
*/
#include "tkPort.h"
#include "Lang.h"
#ifdef TCL_EVENT_IMPLEMENT
#include <signal.h>
/*
* This structure is used to keep track of the notifier info for a
* a registered file.
*/
typedef struct FileHandler {
int fd;
int mask; /* Mask of desired events: TCL_READABLE,
* etc. */
int readyMask; /* Mask of events that have been seen since the
* last time file handlers were invoked for
* this file. */
Tcl_FileProc *proc; /* Procedure to call, in the style of
* Tcl_CreateFileHandler. */
ClientData clientData; /* Argument to pass to proc. */
struct FileHandler *nextPtr;/* Next in list of all files we care about. */
} FileHandler;
/*
* The following structure is what is added to the Tcl event queue when
* file handlers are ready to fire.
*/
typedef struct FileHandlerEvent {
Tcl_Event header; /* Information that is standard for
* all events. */
int fd; /* File descriptor that is ready. Used
* to find the FileHandler structure for
* the file (can't point directly to the
* FileHandler structure because it could
* go away while the event is queued). */
} FileHandlerEvent;
/*
* The following static structure contains the state information for the
* select based implementation of the Tcl notifier.
*/
static struct {
FileHandler *firstFileHandlerPtr;
/* Pointer to head of file handler list. */
fd_mask checkMasks[3*MASK_SIZE];
/* This array is used to build up the masks
* to be used in the next call to select.
* Bits are set in response to calls to
* Tcl_CreateFileHandler. */
fd_mask readyMasks[3*MASK_SIZE];
/* This array reflects the readable/writable
* conditions that were found to exist by the
* last call to select. */
int numFdBits; /* Number of valid bits in checkMasks
* (one more than highest fd for which
* Tcl_WatchFile has been called). */
} notifier;
/*
* The following static indicates whether this module has been initialized.
*/
static int initialized = 0;
/*
* Static routines defined in this file.
*/
static void InitNotifier _ANSI_ARGS_((void));
static void NotifierExitHandler _ANSI_ARGS_((
ClientData clientData));
static int FileHandlerEventProc _ANSI_ARGS_((Tcl_Event *evPtr,
int flags));
/*
*----------------------------------------------------------------------
*
* InitNotifier --
*
* Initializes the notifier state.
*
* Results:
* None.
*
* Side effects:
* Creates a new exit handler.
*
*----------------------------------------------------------------------
*/
static void
InitNotifier()
{
initialized = 1;
memset(¬ifier, 0, sizeof(notifier));
Tcl_CreateExitHandler(NotifierExitHandler, NULL);
}
/*
*----------------------------------------------------------------------
*
* NotifierExitHandler --
*
* This function is called to cleanup the notifier state before
* Tcl is unloaded.
*
* Results:
* None.
*
* Side effects:
* Destroys the notifier window.
*
*----------------------------------------------------------------------
*/
static void
NotifierExitHandler(clientData)
ClientData clientData; /* Not used. */
{
initialized = 0;
}
/*
*----------------------------------------------------------------------
*
* Tcl_SetTimer --
*
* This procedure sets the current notifier timer value. This
* interface is not implemented in this notifier because we are
* always running inside of Tcl_DoOneEvent.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
void
Tcl_SetTimer(timePtr)
Tcl_Time *timePtr; /* Timeout value, may be NULL. */
{
/*
* The interval timer doesn't do anything in this implementation,
* because the only event loop is via Tcl_DoOneEvent, which passes
* timeout values to Tcl_WaitForEvent.
*/
}
/*
*----------------------------------------------------------------------
*
* Tcl_CreateFileHandler --
*
* This procedure registers a file handler with the Xt notifier.
*
* Results:
* None.
*
* Side effects:
* Creates a new file handler structure and registers one or more
* input procedures with Xt.
*
*----------------------------------------------------------------------
*/
void
Tcl_CreateFileHandler(fd, mask, proc, clientData)
int fd; /* Handle of stream to watch. */
int mask; /* OR'ed combination of TCL_READABLE,
* TCL_WRITABLE, and TCL_EXCEPTION:
* indicates conditions under which
* proc should be called. */
Tcl_FileProc *proc; /* Procedure to call for each
* selected event. */
ClientData clientData; /* Arbitrary data to pass to proc. */
{
FileHandler *filePtr;
int index, bit;
if (!initialized) {
InitNotifier();
}
for (filePtr = notifier.firstFileHandlerPtr; filePtr != NULL;
filePtr = filePtr->nextPtr) {
if (filePtr->fd == fd) {
break;
}
}
if (filePtr == NULL) {
filePtr = (FileHandler*) ckalloc(sizeof(FileHandler)); /* MLK */
filePtr->fd = fd;
filePtr->readyMask = 0;
filePtr->nextPtr = notifier.firstFileHandlerPtr;
notifier.firstFileHandlerPtr = filePtr;
}
filePtr->proc = proc;
filePtr->clientData = clientData;
filePtr->mask = mask;
/*
* Update the check masks for this file.
*/
index = fd/(NBBY*sizeof(fd_mask));
bit = 1 << (fd%(NBBY*sizeof(fd_mask)));
if (mask & TCL_READABLE) {
notifier.checkMasks[index] |= bit;
} else {
notifier.checkMasks[index] &= ~bit;
}
if (mask & TCL_WRITABLE) {
(notifier.checkMasks+MASK_SIZE)[index] |= bit;
} else {
(notifier.checkMasks+MASK_SIZE)[index] &= ~bit;
}
if (mask & TCL_EXCEPTION) {
(notifier.checkMasks+2*(MASK_SIZE))[index] |= bit;
} else {
(notifier.checkMasks+2*(MASK_SIZE))[index] &= ~bit;
}
if (notifier.numFdBits <= fd) {
notifier.numFdBits = fd+1;
}
}
/*
*----------------------------------------------------------------------
*
* Tcl_DeleteFileHandler --
*
* Cancel a previously-arranged callback arrangement for
* a file.
*
* Results:
* None.
*
* Side effects:
* If a callback was previously registered on file, remove it.
*
*----------------------------------------------------------------------
*/
void
Tcl_DeleteFileHandler(fd)
int fd; /* Stream id for which to remove callback procedure. */
{
FileHandler *filePtr, *prevPtr;
int index, bit, i;
unsigned long flags;
if (!initialized) {
InitNotifier();
}
/*
* Find the entry for the given file (and return if there
* isn't one).
*/
for (prevPtr = NULL, filePtr = notifier.firstFileHandlerPtr; ;
prevPtr = filePtr, filePtr = filePtr->nextPtr) {
if (filePtr == NULL) {
return;
}
if (filePtr->fd == fd) {
break;
}
}
/*
* Update the check masks for this file.
*/
index = fd/(NBBY*sizeof(fd_mask));
bit = 1 << (fd%(NBBY*sizeof(fd_mask)));
if (filePtr->mask & TCL_READABLE) {
notifier.checkMasks[index] &= ~bit;
}
if (filePtr->mask & TCL_WRITABLE) {
(notifier.checkMasks+MASK_SIZE)[index] &= ~bit;
}
if (filePtr->mask & TCL_EXCEPTION) {
(notifier.checkMasks+2*(MASK_SIZE))[index] &= ~bit;
}
/*
* Find current max fd.
*/
if (fd+1 == notifier.numFdBits) {
for (notifier.numFdBits = 0; index >= 0; index--) {
flags = notifier.checkMasks[index]
| (notifier.checkMasks+MASK_SIZE)[index]
| (notifier.checkMasks+2*(MASK_SIZE))[index];
if (flags) {
for (i = (NBBY*sizeof(fd_mask)); i > 0; i--) {
if (flags & (((unsigned long)1) << (i-1))) {
break;
}
}
notifier.numFdBits = index * (NBBY*sizeof(fd_mask)) + i;
break;
}
}
}
/*
* Clean up information in the callback record.
*/
if (prevPtr == NULL) {
notifier.firstFileHandlerPtr = filePtr->nextPtr;
} else {
prevPtr->nextPtr = filePtr->nextPtr;
}
ckfree((char *) filePtr);
}
#if defined(__EMX__) && (defined(__WIN32__) || defined(__PM__))
/* Backdoor into processing of events when from Tk. */
int (*Tcl_WaitForEventProc)(int, fd_mask *, Tcl_Time *) = NULL;
#endif
/*
*----------------------------------------------------------------------
*
* FileHandlerEventProc --
*
* This procedure is called by Tcl_ServiceEvent when a file event
* reaches the front of the event queue. This procedure is
* responsible for actually handling the event by invoking the
* callback for the file handler.
*
* Results:
* Returns 1 if the event was handled, meaning it should be removed
* from the queue. Returns 0 if the event was not handled, meaning
* it should stay on the queue. The only time the event isn't
* handled is if the TCL_FILE_EVENTS flag bit isn't set.
*
* Side effects:
* Whatever the file handler's callback procedure does.
*
*----------------------------------------------------------------------
*/
static int
FileHandlerEventProc(evPtr, flags)
Tcl_Event *evPtr; /* Event to service. */
int flags; /* Flags that indicate what events to
* handle, such as TCL_FILE_EVENTS. */
{
FileHandler *filePtr;
FileHandlerEvent *fileEvPtr = (FileHandlerEvent *) evPtr;
int mask;
if (!(flags & TCL_FILE_EVENTS)) {
return 0;
}
/*
* Search through the file handlers to find the one whose handle matches
* the event. We do this rather than keeping a pointer to the file
* handler directly in the event, so that the handler can be deleted
* while the event is queued without leaving a dangling pointer.
*/
for (filePtr = notifier.firstFileHandlerPtr; filePtr != NULL;
filePtr = filePtr->nextPtr) {
if (filePtr->fd != fileEvPtr->fd) {
continue;
}
/*
* The code is tricky for two reasons:
* 1. The file handler's desired events could have changed
* since the time when the event was queued, so AND the
* ready mask with the desired mask.
* 2. The file could have been closed and re-opened since
* the time when the event was queued. This is why the
* ready mask is stored in the file handler rather than
* the queued event: it will be zeroed when a new
* file handler is created for the newly opened file.
*/
mask = filePtr->readyMask & filePtr->mask;
filePtr->readyMask = 0;
if (mask != 0) {
(*filePtr->proc)(filePtr->clientData, mask);
}
break;
}
return 1;
}
/*
*----------------------------------------------------------------------
*
* Tcl_WaitForEvent --
*
* This function is called by Tcl_DoOneEvent to wait for new
* events on the message queue. If the block time is 0, then
* Tcl_WaitForEvent just polls without blocking.
*
* Results:
* Returns -1 if the select would block forever, otherwise
* returns 0.
*
* Side effects:
* Queues file events that are detected by the select.
*
*----------------------------------------------------------------------
*/
int
Tcl_WaitForEvent(timePtr)
Tcl_Time *timePtr; /* Maximum block time, or NULL. */
{
FileHandler *filePtr;
FileHandlerEvent *fileEvPtr;
struct timeval timeout, *timeoutPtr;
int bit, index, mask, numFound;
if (!initialized) {
InitNotifier();
}
/*
* Set up the timeout structure. Note that if there are no events to
* check for, we return with a negative result rather than blocking
* forever.
*/
if (timePtr) {
timeout.tv_sec = timePtr->sec;
timeout.tv_usec = timePtr->usec;
timeoutPtr = &timeout;
} else if (
notifier.numFdBits == 0
#if defined(__EMX__) && (defined(__WIN32__) || defined(__PM__))
&& !Tcl_WaitForEventProc
#endif
) {
return -1;
} else {
timeoutPtr = NULL;
}
memcpy((VOID *) notifier.readyMasks, (VOID *) notifier.checkMasks,
3*MASK_SIZE*sizeof(fd_mask));
#if defined(__EMX__) && (defined(__WIN32__) || defined(__PM__))
if (Tcl_WaitForEventProc) {
numFound = (*Tcl_WaitForEventProc)(notifier.numFdBits,
notifier.readyMasks, timePtr);
} else
#endif
numFound = select(notifier.numFdBits,
(SELECT_MASK *) ¬ifier.readyMasks[0],
(SELECT_MASK *) ¬ifier.readyMasks[MASK_SIZE],
(SELECT_MASK *) ¬ifier.readyMasks[2*MASK_SIZE], timeoutPtr);
/*
* Some systems don't clear the masks after an error, so
* we have to do it here.
*/
if (numFound == -1) {
memset((VOID *) notifier.readyMasks, 0, 3*MASK_SIZE*sizeof(fd_mask));
}
/*
* Queue all detected file events before returning.
*/
for (filePtr = notifier.firstFileHandlerPtr;
(filePtr != NULL) && (numFound > 0);
filePtr = filePtr->nextPtr) {
index = filePtr->fd / (NBBY*sizeof(fd_mask));
bit = 1 << (filePtr->fd % (NBBY*sizeof(fd_mask)));
mask = 0;
if (notifier.readyMasks[index] & bit) {
mask |= TCL_READABLE;
}
if ((notifier.readyMasks+MASK_SIZE)[index] & bit) {
mask |= TCL_WRITABLE;
}
if ((notifier.readyMasks+2*(MASK_SIZE))[index] & bit) {
mask |= TCL_EXCEPTION;
}
if (!mask) {
continue;
} else {
numFound--;
}
/*
* Don't bother to queue an event if the mask was previously
* non-zero since an event must still be on the queue.
*/
if (filePtr->readyMask == 0) {
fileEvPtr = (FileHandlerEvent *) ckalloc(
sizeof(FileHandlerEvent));
fileEvPtr->header.proc = FileHandlerEventProc;
fileEvPtr->fd = filePtr->fd;
Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL);
}
filePtr->readyMask = mask;
}
return 0;
}
#endif