src/c_tcl_base_7_5_w_mods/tclwinchan.c

/* $Header: /cvsroot/esrg/sfesrg/esrgpcpj/shared/tcl_base/tclwinchan.c,v 1.1.1.1 2001/06/13 04:48:23 dtashley Exp $ */

/* 
 * tclWinChan.c
 *
 *      Channel drivers for Windows channels based on files, command
 *      pipes and TCP sockets.
 *
 * 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: tclwinchan.c,v 1.1.1.1 2001/06/13 04:48:23 dtashley Exp $
 */

#include "tclWinInt.h"

/*
 * State flags used in the info structures below.
 */

#define FILE_PENDING    (1<<0)  /* Message is pending in the queue. */
#define FILE_ASYNC      (1<<1)  /* Channel is non-blocking. */
#define FILE_APPEND     (1<<2)  /* File is in append mode. */

#define FILE_TYPE_SERIAL  (FILE_TYPE_PIPE+1)
#define FILE_TYPE_CONSOLE (FILE_TYPE_PIPE+2)

/*
 * The following structure contains per-instance data for a file based channel.
 */

typedef struct FileInfo {
    Tcl_Channel channel;        /* Pointer to channel structure. */
    int validMask;              /* OR'ed combination of TCL_READABLE,
                                 * TCL_WRITABLE, or TCL_EXCEPTION: indicates
                                 * which operations are valid on the file. */
    int watchMask;              /* OR'ed combination of TCL_READABLE,
                                 * TCL_WRITABLE, or TCL_EXCEPTION: indicates
                                 * which events should be reported. */
    int flags;                  /* State flags, see above for a list. */
    HANDLE handle;              /* Input/output file. */
    struct FileInfo *nextPtr;   /* Pointer to next registered file. */
} FileInfo;

typedef struct ThreadSpecificData {
    /*
     * List of all file channels currently open.
     */

    FileInfo *firstFilePtr;
} ThreadSpecificData;

static Tcl_ThreadDataKey dataKey;

/*
 * The following structure is what is added to the Tcl event queue when
 * file events are generated.
 */

typedef struct FileEvent {
    Tcl_Event header;           /* Information that is standard for
                                 * all events. */
    FileInfo *infoPtr;          /* Pointer to file info structure.  Note
                                 * that we still have to verify that the
                                 * file exists before dereferencing this
                                 * pointer. */
} FileEvent;

/*
 * Static routines for this file:
 */

static int              FileBlockProc _ANSI_ARGS_((ClientData instanceData,
                            int mode));
static void             FileChannelExitHandler _ANSI_ARGS_((
                            ClientData clientData));
static void             FileCheckProc _ANSI_ARGS_((ClientData clientData,
                            int flags));
static int              FileCloseProc _ANSI_ARGS_((ClientData instanceData,
                            Tcl_Interp *interp));
static int              FileEventProc _ANSI_ARGS_((Tcl_Event *evPtr, 
                            int flags));
static int              FileGetHandleProc _ANSI_ARGS_((ClientData instanceData,
                            int direction, ClientData *handlePtr));
static ThreadSpecificData *FileInit _ANSI_ARGS_((void));
static int              FileInputProc _ANSI_ARGS_((ClientData instanceData,
                            char *buf, int toRead, int *errorCode));
static int              FileOutputProc _ANSI_ARGS_((ClientData instanceData,
                            char *buf, int toWrite, int *errorCode));
static int              FileSeekProc _ANSI_ARGS_((ClientData instanceData,
                            long offset, int mode, int *errorCode));
static void             FileSetupProc _ANSI_ARGS_((ClientData clientData,
                            int flags));
static void             FileWatchProc _ANSI_ARGS_((ClientData instanceData,
                            int mask));

                            
/*
 * This structure describes the channel type structure for file based IO.
 */

static Tcl_ChannelType fileChannelType = {
    "file",                     /* Type name. */
    FileBlockProc,              /* Set blocking or non-blocking mode.*/
    FileCloseProc,              /* Close proc. */
    FileInputProc,              /* Input proc. */
    FileOutputProc,             /* Output proc. */
    FileSeekProc,               /* Seek proc. */
    NULL,                       /* Set option proc. */
    NULL,                       /* Get option proc. */
    FileWatchProc,              /* Set up the notifier to watch the channel. */
    FileGetHandleProc,          /* Get an OS handle from channel. */
};


/*
 *----------------------------------------------------------------------
 *
 * FileInit --
 *
 *      This function creates the window used to simulate file events.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Creates a new window and creates an exit handler. 
 *
 *----------------------------------------------------------------------
 */

static ThreadSpecificData *
FileInit()
{
    ThreadSpecificData *tsdPtr =
        (ThreadSpecificData *)TclThreadDataKeyGet(&dataKey);
    if (tsdPtr == NULL) {
        tsdPtr = TCL_TSD_INIT(&dataKey);
        tsdPtr->firstFilePtr = NULL;
        Tcl_CreateEventSource(FileSetupProc, FileCheckProc, NULL);
        Tcl_CreateThreadExitHandler(FileChannelExitHandler, NULL);
    }
    return tsdPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * FileChannelExitHandler --
 *
 *      This function is called to cleanup the channel driver before
 *      Tcl is unloaded.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Destroys the communication window.
 *
 *----------------------------------------------------------------------
 */

static void
FileChannelExitHandler(clientData)
    ClientData clientData;      /* Old window proc */
{
    Tcl_DeleteEventSource(FileSetupProc, FileCheckProc, NULL);
}

/*
 *----------------------------------------------------------------------
 *
 * FileSetupProc --
 *
 *      This procedure is invoked before Tcl_DoOneEvent blocks waiting
 *      for an event.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Adjusts the block time if needed.
 *
 *----------------------------------------------------------------------
 */

void
FileSetupProc(data, flags)
    ClientData data;            /* Not used. */
    int flags;                  /* Event flags as passed to Tcl_DoOneEvent. */
{
    FileInfo *infoPtr;
    Tcl_Time blockTime = { 0, 0 };
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    if (!(flags & TCL_FILE_EVENTS)) {
        return;
    }
    
    /*
     * Check to see if there is a ready file.  If so, poll.
     */

    for (infoPtr = tsdPtr->firstFilePtr; infoPtr != NULL; 
            infoPtr = infoPtr->nextPtr) {
        if (infoPtr->watchMask) {
            Tcl_SetMaxBlockTime(&blockTime);
            break;
        }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * FileCheckProc --
 *
 *      This procedure is called by Tcl_DoOneEvent to check the file
 *      event source for events. 
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      May queue an event.
 *
 *----------------------------------------------------------------------
 */

static void
FileCheckProc(data, flags)
    ClientData data;            /* Not used. */
    int flags;                  /* Event flags as passed to Tcl_DoOneEvent. */
{
    FileEvent *evPtr;
    FileInfo *infoPtr;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    if (!(flags & TCL_FILE_EVENTS)) {
        return;
    }
    
    /*
     * Queue events for any ready files that don't already have events
     * queued (caused by persistent states that won't generate WinSock
     * events).
     */

    for (infoPtr = tsdPtr->firstFilePtr; infoPtr != NULL; 
            infoPtr = infoPtr->nextPtr) {
        if (infoPtr->watchMask && !(infoPtr->flags & FILE_PENDING)) {
            infoPtr->flags |= FILE_PENDING;
            evPtr = (FileEvent *) ckalloc(sizeof(FileEvent));
            evPtr->header.proc = FileEventProc;
            evPtr->infoPtr = infoPtr;
            Tcl_QueueEvent((Tcl_Event *) evPtr, TCL_QUEUE_TAIL);
        }
    }
}

/*----------------------------------------------------------------------
 *
 * FileEventProc --
 *
 *      This function is invoked by Tcl_ServiceEvent when a file event
 *      reaches the front of the event queue.  This procedure invokes
 *      Tcl_NotifyChannel on the file.
 *
 * 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 notifier callback does.
 *
 *----------------------------------------------------------------------
 */

static int
FileEventProc(evPtr, flags)
    Tcl_Event *evPtr;           /* Event to service. */
    int flags;                  /* Flags that indicate what events to
                                 * handle, such as TCL_FILE_EVENTS. */
{
    FileEvent *fileEvPtr = (FileEvent *)evPtr;
    FileInfo *infoPtr;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    if (!(flags & TCL_FILE_EVENTS)) {
        return 0;
    }

    /*
     * Search through the list of watched files for the one whose handle
     * matches the event.  We do this rather than simply dereferencing
     * the handle in the event so that files can be deleted while the
     * event is in the queue.
     */

    for (infoPtr = tsdPtr->firstFilePtr; infoPtr != NULL;
            infoPtr = infoPtr->nextPtr) {
        if (fileEvPtr->infoPtr == infoPtr) {
            infoPtr->flags &= ~(FILE_PENDING);
            Tcl_NotifyChannel(infoPtr->channel, infoPtr->watchMask);
            break;
        }
    }
    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * FileBlockProc --
 *
 *      Set blocking or non-blocking mode on channel.
 *
 * Results:
 *      0 if successful, errno when failed.
 *
 * Side effects:
 *      Sets the device into blocking or non-blocking mode.
 *
 *----------------------------------------------------------------------
 */

static int
FileBlockProc(instanceData, mode)
    ClientData instanceData;    /* Instance data for channel. */
    int mode;                   /* TCL_MODE_BLOCKING or
                                 * TCL_MODE_NONBLOCKING. */
{
    FileInfo *infoPtr = (FileInfo *) instanceData;
    
    /*
     * Files on Windows can not be switched between blocking and nonblocking,
     * hence we have to emulate the behavior. This is done in the input
     * function by checking against a bit in the state. We set or unset the
     * bit here to cause the input function to emulate the correct behavior.
     */

    if (mode == TCL_MODE_NONBLOCKING) {
        infoPtr->flags |= FILE_ASYNC;
    } else {
        infoPtr->flags &= ~(FILE_ASYNC);
    }
    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * FileCloseProc --
 *
 *      Closes the IO channel.
 *
 * Results:
 *      0 if successful, the value of errno if failed.
 *
 * Side effects:
 *      Closes the physical channel
 *
 *----------------------------------------------------------------------
 */

static int
FileCloseProc(instanceData, interp)
    ClientData instanceData;    /* Pointer to FileInfo structure. */
    Tcl_Interp *interp;         /* Not used. */
{
    FileInfo *fileInfoPtr = (FileInfo *) instanceData;
    FileInfo **nextPtrPtr;
    int errorCode = 0;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    /*
     * Remove the file from the watch list.
     */

    FileWatchProc(instanceData, 0);

    /*
     * Don't close the Win32 handle if the handle is a standard channel
     * during the exit process.  Otherwise, one thread may kill the stdio
     * of another.
     */

    if (!TclInExit() 
            || ((GetStdHandle(STD_INPUT_HANDLE) != fileInfoPtr->handle)
                && (GetStdHandle(STD_OUTPUT_HANDLE) != fileInfoPtr->handle)
                && (GetStdHandle(STD_ERROR_HANDLE) != fileInfoPtr->handle))) {
        if (CloseHandle(fileInfoPtr->handle) == FALSE) {
            TclWinConvertError(GetLastError());
            errorCode = errno;
        }
    }
    for (nextPtrPtr = &(tsdPtr->firstFilePtr); (*nextPtrPtr) != NULL;
         nextPtrPtr = &((*nextPtrPtr)->nextPtr)) {
        if ((*nextPtrPtr) == fileInfoPtr) {
            (*nextPtrPtr) = fileInfoPtr->nextPtr;
            break;
        }
    }
    ckfree((char *)fileInfoPtr);
    return errorCode;
}

/*
 *----------------------------------------------------------------------
 *
 * FileSeekProc --
 *
 *      Seeks on a file-based channel. Returns the new position.
 *
 * Results:
 *      -1 if failed, the new position if successful. If failed, it
 *      also sets *errorCodePtr to the error code.
 *
 * Side effects:
 *      Moves the location at which the channel will be accessed in
 *      future operations.
 *
 *----------------------------------------------------------------------
 */

static int
FileSeekProc(instanceData, offset, mode, errorCodePtr)
    ClientData instanceData;                    /* File state. */
    long offset;                                /* Offset to seek to. */
    int mode;                                   /* Relative to where
                                                 * should we seek? */
    int *errorCodePtr;                          /* To store error code. */
{
    FileInfo *infoPtr = (FileInfo *) instanceData;
    DWORD moveMethod;
    DWORD newPos;

    *errorCodePtr = 0;
    if (mode == SEEK_SET) {
        moveMethod = FILE_BEGIN;
    } else if (mode == SEEK_CUR) {
        moveMethod = FILE_CURRENT;
    } else {
        moveMethod = FILE_END;
    }

    newPos = SetFilePointer(infoPtr->handle, offset, NULL, moveMethod);
    if (newPos == 0xFFFFFFFF) {
        TclWinConvertError(GetLastError());
        *errorCodePtr = errno;
        return -1;
    }
    return newPos;
}

/*
 *----------------------------------------------------------------------
 *
 * FileInputProc --
 *
 *      Reads input from the IO channel into the buffer given. Returns
 *      count of how many bytes were actually read, and an error indication.
 *
 * Results:
 *      A count of how many bytes were read is returned and an error
 *      indication is returned in an output argument.
 *
 * Side effects:
 *      Reads input from the actual channel.
 *
 *----------------------------------------------------------------------
 */

static int
FileInputProc(instanceData, buf, bufSize, errorCode)
    ClientData instanceData;            /* File state. */
    char *buf;                          /* Where to store data read. */
    int bufSize;                        /* How much space is available
                                         * in the buffer? */
    int *errorCode;                     /* Where to store error code. */
{
    FileInfo *infoPtr;
    DWORD bytesRead;

    *errorCode = 0;
    infoPtr = (FileInfo *) instanceData;

    /*
     * Note that we will block on reads from a console buffer until a
     * full line has been entered.  The only way I know of to get
     * around this is to write a console driver.  We should probably
     * do this at some point, but for now, we just block.  The same
     * problem exists for files being read over the network.
     */

    if (ReadFile(infoPtr->handle, (LPVOID) buf, (DWORD) bufSize, &bytesRead,
            (LPOVERLAPPED) NULL) != FALSE) {
        return bytesRead;
    }
    
    TclWinConvertError(GetLastError());
    *errorCode = errno;
    if (errno == EPIPE) {
        return 0;
    }
    return -1;
}

/*
 *----------------------------------------------------------------------
 *
 * FileOutputProc --
 *
 *      Writes the given output on the IO channel. Returns count of how
 *      many characters were actually written, and an error indication.
 *
 * Results:
 *      A count of how many characters were written is returned and an
 *      error indication is returned in an output argument.
 *
 * Side effects:
 *      Writes output on the actual channel.
 *
 *----------------------------------------------------------------------
 */

static int
FileOutputProc(instanceData, buf, toWrite, errorCode)
    ClientData instanceData;            /* File state. */
    char *buf;                          /* The data buffer. */
    int toWrite;                        /* How many bytes to write? */
    int *errorCode;                     /* Where to store error code. */
{
    FileInfo *infoPtr = (FileInfo *) instanceData;
    DWORD bytesWritten;
    
    *errorCode = 0;

    /*
     * If we are writing to a file that was opened with O_APPEND, we need to
     * seek to the end of the file before writing the current buffer.
     */

    if (infoPtr->flags & FILE_APPEND) {
        SetFilePointer(infoPtr->handle, 0, NULL, FILE_END);
    }

    if (WriteFile(infoPtr->handle, (LPVOID) buf, (DWORD) toWrite, &bytesWritten,
            (LPOVERLAPPED) NULL) == FALSE) {
        TclWinConvertError(GetLastError());
        *errorCode = errno;
        return -1;
    }
    FlushFileBuffers(infoPtr->handle);
    return bytesWritten;
}

/*
 *----------------------------------------------------------------------
 *
 * FileWatchProc --
 *
 *      Called by the notifier to set up to watch for events on this
 *      channel.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static void
FileWatchProc(instanceData, mask)
    ClientData instanceData;            /* File state. */
    int mask;                           /* What events to watch for; OR-ed
                                         * combination of TCL_READABLE,
                                         * TCL_WRITABLE and TCL_EXCEPTION. */
{
    FileInfo *infoPtr = (FileInfo *) instanceData;
    Tcl_Time blockTime = { 0, 0 };

    /*
     * Since the file is always ready for events, we set the block time
     * to zero so we will poll.
     */

    infoPtr->watchMask = mask & infoPtr->validMask;
    if (infoPtr->watchMask) {
        Tcl_SetMaxBlockTime(&blockTime);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * FileGetHandleProc --
 *
 *      Called from Tcl_GetChannelHandle to retrieve OS handles from
 *      a file based channel.
 *
 * Results:
 *      Returns TCL_OK with the fd in handlePtr, or TCL_ERROR if
 *      there is no handle for the specified direction. 
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static int
FileGetHandleProc(instanceData, direction, handlePtr)
    ClientData instanceData;    /* The file state. */
    int direction;              /* TCL_READABLE or TCL_WRITABLE */
    ClientData *handlePtr;      /* Where to store the handle.  */
{
    FileInfo *infoPtr = (FileInfo *) instanceData;

    if (direction & infoPtr->validMask) {
        *handlePtr = (ClientData) infoPtr->handle;
        return TCL_OK;
    } else {
        return TCL_ERROR;
    }
}


/*
 *----------------------------------------------------------------------
 *
 * TclpOpenFileChannel --
 *
 *      Open an File based channel on Unix systems.
 *
 * Results:
 *      The new channel or NULL. If NULL, the output argument
 *      errorCodePtr is set to a POSIX error.
 *
 * Side effects:
 *      May open the channel and may cause creation of a file on the
 *      file system.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
TclpOpenFileChannel(interp, fileName, modeString, permissions)
    Tcl_Interp *interp;                 /* Interpreter for error reporting;
                                         * can be NULL. */
    char *fileName;                     /* Name of file to open. */
    char *modeString;                   /* A list of POSIX open modes or
                                         * a string such as "rw". */
    int permissions;                    /* If the open involves creating a
                                         * file, with what modes to create
                                         * it? */
{
    Tcl_Channel channel = 0;
    int seekFlag, mode, channelPermissions;
    DWORD accessMode, createMode, shareMode, flags, consoleParams, type;
    TCHAR *nativeName;
    Tcl_DString ds, buffer;
    DCB dcb;
    HANDLE handle;
    char channelName[16 + TCL_INTEGER_SPACE];
    TclFile readFile = NULL;
    TclFile writeFile = NULL;

    mode = TclGetOpenMode(interp, modeString, &seekFlag);
    if (mode == -1) {
        return NULL;
    }

    if (Tcl_TranslateFileName(interp, fileName, &ds) == NULL) {
        return NULL;
    }
    nativeName = Tcl_WinUtfToTChar(Tcl_DStringValue(&ds), 
            Tcl_DStringLength(&ds), &buffer);

    switch (mode & (O_RDONLY | O_WRONLY | O_RDWR)) {
        case O_RDONLY:
            accessMode = GENERIC_READ;
            channelPermissions = TCL_READABLE;
            break;
        case O_WRONLY:
            accessMode = GENERIC_WRITE;
            channelPermissions = TCL_WRITABLE;
            break;
        case O_RDWR:
            accessMode = (GENERIC_READ | GENERIC_WRITE);
            channelPermissions = (TCL_READABLE | TCL_WRITABLE);
            break;
        default:
            panic("TclpOpenFileChannel: invalid mode value");
            break;
    }

    /*
     * Map the creation flags to the NT create mode.
     */

    switch (mode & (O_CREAT | O_EXCL | O_TRUNC)) {
        case (O_CREAT | O_EXCL):
        case (O_CREAT | O_EXCL | O_TRUNC):
            createMode = CREATE_NEW;
            break;
        case (O_CREAT | O_TRUNC):
            createMode = CREATE_ALWAYS;
            break;
        case O_CREAT:
            createMode = OPEN_ALWAYS;
            break;
        case O_TRUNC:
        case (O_TRUNC | O_EXCL):
            createMode = TRUNCATE_EXISTING;
            break;
        default:
            createMode = OPEN_EXISTING;
            break;
    }

    /*
     * If the file is being created, get the file attributes from the
     * permissions argument, else use the existing file attributes.
     */

    if (mode & O_CREAT) {
        if (permissions & S_IWRITE) {
            flags = FILE_ATTRIBUTE_NORMAL;
        } else {
            flags = FILE_ATTRIBUTE_READONLY;
        }
    } else {
        flags = (*tclWinProcs->getFileAttributesProc)(nativeName);
        if (flags == 0xFFFFFFFF) {
            flags = 0;
        }
    }

    /*
     * Set up the file sharing mode.  We want to allow simultaneous access.
     */

    shareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;

    /*
     * Now we get to create the file.
     */

    handle = (*tclWinProcs->createFileProc)(nativeName, accessMode, 
            shareMode, NULL, createMode, flags, (HANDLE) NULL);

    if (handle == INVALID_HANDLE_VALUE) {
        DWORD err;
        err = GetLastError();
        if ((err & 0xffffL) == ERROR_OPEN_FAILED) {
            err = (mode & O_CREAT) ? ERROR_FILE_EXISTS : ERROR_FILE_NOT_FOUND;
        }
        TclWinConvertError(err);
        if (interp != (Tcl_Interp *) NULL) {
            Tcl_AppendResult(interp, "couldn't open \"", fileName, "\": ",
                             Tcl_PosixError(interp), (char *) NULL);
        }
        Tcl_DStringFree(&buffer);
        return NULL;
    }
    
    type = GetFileType(handle);

    /*
     * If the file is a character device, we need to try to figure out
     * whether it is a serial port, a console, or something else.  We
     * test for the console case first because this is more common.
     */

    if (type == FILE_TYPE_CHAR) {
        if (GetConsoleMode(handle, &consoleParams)) {
            type = FILE_TYPE_CONSOLE;
        } else {
            dcb.DCBlength = sizeof( DCB ) ;
            if (GetCommState(handle, &dcb)) {
                type = FILE_TYPE_SERIAL;
            }
                    
        }
    }

    channel = NULL;

    switch (type) {
    case FILE_TYPE_SERIAL:
        channel = TclWinOpenSerialChannel(handle, channelName,
                channelPermissions);
        break;
    case FILE_TYPE_CONSOLE:
        channel = TclWinOpenConsoleChannel(handle, channelName,
                channelPermissions);
        break;
    case FILE_TYPE_PIPE:
        if (channelPermissions & TCL_READABLE) {
            readFile = TclWinMakeFile(handle);
        }
        if (channelPermissions & TCL_WRITABLE) {
            writeFile = TclWinMakeFile(handle);
        }
        channel = TclpCreateCommandChannel(readFile, writeFile, NULL, 0, NULL);
        break;
    case FILE_TYPE_CHAR:
    case FILE_TYPE_DISK:
    case FILE_TYPE_UNKNOWN:
        channel = TclWinOpenFileChannel(handle, channelName,
                                        channelPermissions,
                                        (mode & O_APPEND) ? FILE_APPEND : 0);
        break;

    default:
        /*
         * The handle is of an unknown type, probably /dev/nul equivalent
         * or possibly a closed handle.  
         */
        
        channel = NULL;
        Tcl_AppendResult(interp, "couldn't open \"", fileName, "\": ",
                "bad file type", (char *) NULL);
        break;
    }

    Tcl_DStringFree(&buffer);
    Tcl_DStringFree(&ds);

    if (channel != NULL) {
        if (seekFlag) {
            if (Tcl_Seek(channel, 0, SEEK_END) < 0) {
                if (interp != (Tcl_Interp *) NULL) {
                    Tcl_AppendResult(interp,
                            "could not seek to end of file on \"",
                            channelName, "\": ", Tcl_PosixError(interp),
                            (char *) NULL);
                }
                Tcl_Close(NULL, channel);
                return NULL;
            }
        }
    }
    return channel;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_MakeFileChannel --
 *
 *      Creates a Tcl_Channel from an existing platform specific file
 *      handle.
 *
 * Results:
 *      The Tcl_Channel created around the preexisting file.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
Tcl_MakeFileChannel(rawHandle, mode)
    ClientData rawHandle;       /* OS level handle */
    int mode;                   /* ORed combination of TCL_READABLE and
                                 * TCL_WRITABLE to indicate file mode. */
{
    char channelName[16 + TCL_INTEGER_SPACE];
    Tcl_Channel channel = NULL;
    HANDLE handle = (HANDLE) rawHandle;
    DCB dcb;
    DWORD consoleParams;
    DWORD type;
    TclFile readFile = NULL;
    TclFile writeFile = NULL;

    if (mode == 0) {
        return NULL;
    }

    type = GetFileType(handle);

    /*
     * If the file is a character device, we need to try to figure out
     * whether it is a serial port, a console, or something else.  We
     * test for the console case first because this is more common.
     */

    if (type == FILE_TYPE_CHAR) {
        if (GetConsoleMode(handle, &consoleParams)) {
            type = FILE_TYPE_CONSOLE;
        } else {
            dcb.DCBlength = sizeof( DCB ) ;
            if (GetCommState(handle, &dcb)) {
                type = FILE_TYPE_SERIAL;
            }
        }
    }

    switch (type)
    {
    case FILE_TYPE_SERIAL:
        channel = TclWinOpenSerialChannel(handle, channelName, mode);
        break;
    case FILE_TYPE_CONSOLE:
        channel = TclWinOpenConsoleChannel(handle, channelName, mode);
        break;
    case FILE_TYPE_PIPE:
        if (mode & TCL_READABLE)
        {
            readFile = TclWinMakeFile(handle);
        }
        if (mode & TCL_WRITABLE)
        {
            writeFile = TclWinMakeFile(handle);
        }
        channel = TclpCreateCommandChannel(readFile, writeFile, NULL, 0, NULL);
        break;

    case FILE_TYPE_DISK:
    case FILE_TYPE_CHAR:
    case FILE_TYPE_UNKNOWN:
        channel = TclWinOpenFileChannel(handle, channelName, mode, 0);
        break;
        
    default:
        /*
         * The handle is of an unknown type, probably /dev/nul equivalent
         * or possibly a closed handle.
         */
        
        channel = NULL;
        break;

    }

    return channel;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpGetDefaultStdChannel --
 *
 *      Constructs a channel for the specified standard OS handle.
 *
 * Results:
 *      Returns the specified default standard channel, or NULL.
 *
 * Side effects:
 *      May cause the creation of a standard channel and the underlying
 *      file.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
TclpGetDefaultStdChannel(type)
    int type;                   /* One of TCL_STDIN, TCL_STDOUT, TCL_STDERR. */
{
    Tcl_Channel channel;
    HANDLE handle;
    int mode;
    char *bufMode;
    DWORD handleId;             /* Standard handle to retrieve. */

    switch (type) {
        case TCL_STDIN:
            handleId = STD_INPUT_HANDLE;
            mode = TCL_READABLE;
            bufMode = "line";
            break;
        case TCL_STDOUT:
            handleId = STD_OUTPUT_HANDLE;
            mode = TCL_WRITABLE;
            bufMode = "line";
            break;
        case TCL_STDERR:
            handleId = STD_ERROR_HANDLE;
            mode = TCL_WRITABLE;
            bufMode = "none";
            break;
        default:
            panic("TclGetDefaultStdChannel: Unexpected channel type");
            break;
    }

    handle = GetStdHandle(handleId);

    /*
     * Note that we need to check for 0 because Windows may return 0 if this
     * is not a console mode application, even though this is not a valid
     * handle.
     */
    
    if ((handle == INVALID_HANDLE_VALUE) || (handle == 0)) {
        return NULL;
    }
    
    channel = Tcl_MakeFileChannel(handle, mode);

    if (channel == NULL) {
        return NULL;
    }

    /*
     * Set up the normal channel options for stdio handles.
     */

    if ((Tcl_SetChannelOption((Tcl_Interp *) NULL, channel, "-translation",
            "auto") == TCL_ERROR)
            || (Tcl_SetChannelOption((Tcl_Interp *) NULL, channel, "-eofchar",
                    "\032 {}") == TCL_ERROR)
            || (Tcl_SetChannelOption((Tcl_Interp *) NULL, channel,
                    "-buffering", bufMode) == TCL_ERROR)) {
        Tcl_Close((Tcl_Interp *) NULL, channel);
        return (Tcl_Channel) NULL;
    }
    return channel;
}


/*
 *----------------------------------------------------------------------
 *
 * TclWinOpenFileChannel --
 *
 *      Constructs a File channel for the specified standard OS handle.
 *      This is a helper function to break up the construction of 
 *      channels into File, Console, or Serial.
 *
 * Results:
 *      Returns the new channel, or NULL.
 *
 * Side effects:
 *      May open the channel and may cause creation of a file on the
 *      file system.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
TclWinOpenFileChannel(handle, channelName, permissions, appendMode)
    HANDLE handle;
    char *channelName;
    int permissions;
    int appendMode;
{
    FileInfo *infoPtr;
    ThreadSpecificData *tsdPtr;

    tsdPtr = FileInit();

    /*
     * See if a channel with this handle already exists.
     */
    
    for (infoPtr = tsdPtr->firstFilePtr; infoPtr != NULL; 
         infoPtr = infoPtr->nextPtr) {
        if (infoPtr->handle == (HANDLE) handle) {
            return (permissions == infoPtr->validMask) ? infoPtr->channel : NULL;
        }
    }

    infoPtr = (FileInfo *) ckalloc((unsigned) sizeof(FileInfo));
    infoPtr->nextPtr = tsdPtr->firstFilePtr;
    tsdPtr->firstFilePtr = infoPtr;
    infoPtr->validMask = permissions;
    infoPtr->watchMask = 0;
    infoPtr->flags = appendMode;
    infoPtr->handle = handle;
        
    wsprintfA(channelName, "file%lx", (int) infoPtr);
    
    infoPtr->channel = Tcl_CreateChannel(&fileChannelType, channelName,
            (ClientData) infoPtr, permissions);
    
    /*
     * Files have default translation of AUTO and ^Z eof char, which
     * means that a ^Z will be accepted as EOF when reading.
     */
    
    Tcl_SetChannelOption(NULL, infoPtr->channel, "-translation", "auto");
    Tcl_SetChannelOption(NULL, infoPtr->channel, "-eofchar", "\032 {}");

    return infoPtr->channel;
}


/* $History: tclwinchan.c $
 * 
 * *****************  Version 1  *****************
 * User: Dtashley     Date: 1/02/01    Time: 12:51a
 * Created in $/IjuScripter, IjuConsole/Source/Tcl Base
 * Initial check-in.
 */ 

/* End of TCLWINCHAN.C */