summaryrefslogtreecommitdiffstats
path: root/unix/tclUnixNotfy.c
diff options
context:
space:
mode:
Diffstat (limited to 'unix/tclUnixNotfy.c')
-rw-r--r--unix/tclUnixNotfy.c518
1 files changed, 518 insertions, 0 deletions
diff --git a/unix/tclUnixNotfy.c b/unix/tclUnixNotfy.c
new file mode 100644
index 0000000..1a86680
--- /dev/null
+++ b/unix/tclUnixNotfy.c
@@ -0,0 +1,518 @@
+/*
+ * 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.
+ *
+ * SCCS: @(#) tclUnixNotfy.c 1.44 97/11/05 13:02:20
+ */
+
+#include "tclInt.h"
+#include "tclPort.h"
+#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(&notifier, 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);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * 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) {
+ return -1;
+ } else {
+ timeoutPtr = NULL;
+ }
+
+ memcpy((VOID *) notifier.readyMasks, (VOID *) notifier.checkMasks,
+ 3*MASK_SIZE*sizeof(fd_mask));
+ numFound = select(notifier.numFdBits,
+ (SELECT_MASK *) &notifier.readyMasks[0],
+ (SELECT_MASK *) &notifier.readyMasks[MASK_SIZE],
+ (SELECT_MASK *) &notifier.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;
+}