Initial revision

1 files changed, 518 insertions, 0 deletions

diff --git a/unix/tclUnixNotfy.c b/unix/tclUnixNotfy.c
new file mode 100644
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+/*
+ * 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;
+}