Initial revision

1 files changed, 2565 insertions, 0 deletions

diff --git a/unix/tclUnixChan.c b/unix/tclUnixChan.c
new file mode 100644
index 0000000..2c0e996
--- /dev/null
+++ b/unix/tclUnixChan.c
@@ -0,0 +1,2565 @@
+/* 
+ * tclUnixChan.c
+ *
+ *	Common channel driver for Unix 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.
+ *
+ * SCCS: @(#) tclUnixChan.c 1.207 97/11/04 14:45:29
+ */
+
+#include	"tclInt.h"	/* Internal definitions for Tcl. */
+#include	"tclPort.h"	/* Portability features for Tcl. */
+
+/*
+ * sys/ioctl.h has already been included by tclPort.h.  Including termios.h
+ * or termio.h causes a bunch of warning messages because some duplicate
+ * (but not contradictory) #defines exist in termios.h and/or termio.h
+ */
+#undef NL0
+#undef NL1
+#undef CR0
+#undef CR1
+#undef CR2
+#undef CR3
+#undef TAB0
+#undef TAB1
+#undef TAB2
+#undef XTABS
+#undef BS0
+#undef BS1
+#undef FF0
+#undef FF1
+#undef ECHO
+#undef NOFLSH
+#undef TOSTOP
+#undef FLUSHO
+#undef PENDIN
+
+#ifdef USE_TERMIOS
+#   include <termios.h>
+#else	/* !USE_TERMIOS */
+#ifdef USE_TERMIO
+#   include <termio.h>
+#else	/* !USE_TERMIO */
+#ifdef USE_SGTTY
+#   include <sgtty.h>
+#endif	/* USE_SGTTY */
+#endif	/* !USE_TERMIO */
+#endif	/* !USE_TERMIOS */
+
+/*
+ * The following structure is used to set or get the serial port
+ * attributes in a platform-independant manner.
+ */
+ 
+typedef struct TtyAttrs {
+    int baud;
+    int parity;
+    int data;
+    int stop;
+} TtyAttrs;
+
+/*
+ * This structure describes per-instance state of a file based channel.
+ */
+
+typedef struct FileState {
+    Tcl_Channel channel;	/* Channel associated with this file. */
+    int fd;			/* File handle. */
+    int validMask;		/* OR'ed combination of TCL_READABLE,
+				 * TCL_WRITABLE, or TCL_EXCEPTION: indicates
+				 * which operations are valid on the file. */
+    struct FileState *nextPtr;	/* Pointer to next file in list of all
+				 * file channels. */
+} FileState;
+
+/*
+ * List of all file channels currently open.
+ */
+
+static FileState *firstFilePtr = NULL;
+
+/*
+ * This structure describes per-instance state of a tcp based channel.
+ */
+
+typedef struct TcpState {
+    Tcl_Channel channel;	/* Channel associated with this file. */
+    int fd;			/* The socket itself. */
+    int flags;			/* ORed combination of the bitfields
+				 * defined below. */
+    Tcl_TcpAcceptProc *acceptProc;
+				/* Proc to call on accept. */
+    ClientData acceptProcData;	/* The data for the accept proc. */
+} TcpState;
+
+/*
+ * These bits may be ORed together into the "flags" field of a TcpState
+ * structure.
+ */
+
+#define TCP_ASYNC_SOCKET	(1<<0)	/* Asynchronous socket. */
+#define TCP_ASYNC_CONNECT	(1<<1)	/* Async connect in progress. */
+
+/*
+ * The following defines the maximum length of the listen queue. This is
+ * the number of outstanding yet-to-be-serviced requests for a connection
+ * on a server socket, more than this number of outstanding requests and
+ * the connection request will fail.
+ */
+
+#ifndef	SOMAXCONN
+#define SOMAXCONN	100
+#endif
+
+#if	(SOMAXCONN < 100)
+#undef	SOMAXCONN
+#define	SOMAXCONN	100
+#endif
+
+/*
+ * The following defines how much buffer space the kernel should maintain
+ * for a socket.
+ */
+
+#define SOCKET_BUFSIZE	4096
+
+/*
+ * Static routines for this file:
+ */
+
+static TcpState *	CreateSocket _ANSI_ARGS_((Tcl_Interp *interp,
+			    int port, char *host, int server,
+			    char *myaddr, int myport, int async));
+static int		CreateSocketAddress _ANSI_ARGS_(
+			    (struct sockaddr_in *sockaddrPtr,
+			    char *host, int port));
+static int		FileBlockModeProc _ANSI_ARGS_((
+    			    ClientData instanceData, int mode));
+static int		FileCloseProc _ANSI_ARGS_((ClientData instanceData,
+			    Tcl_Interp *interp));
+static int		FileGetHandleProc _ANSI_ARGS_((ClientData instanceData,
+		            int direction, ClientData *handlePtr));
+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		FileWatchProc _ANSI_ARGS_((ClientData instanceData,
+		            int mask));
+static void		TcpAccept _ANSI_ARGS_((ClientData data, int mask));
+static int		TcpBlockModeProc _ANSI_ARGS_((ClientData data,
+        		    int mode));
+static int		TcpCloseProc _ANSI_ARGS_((ClientData instanceData,
+			    Tcl_Interp *interp));
+static int		TcpGetHandleProc _ANSI_ARGS_((ClientData instanceData,
+		            int direction, ClientData *handlePtr));
+static int		TcpGetOptionProc _ANSI_ARGS_((ClientData instanceData,
+			    Tcl_Interp *interp, char *optionName,
+			    Tcl_DString *dsPtr));
+static int		TcpInputProc _ANSI_ARGS_((ClientData instanceData,
+		            char *buf, int toRead,  int *errorCode));
+static int		TcpOutputProc _ANSI_ARGS_((ClientData instanceData,
+		            char *buf, int toWrite, int *errorCode));
+static void		TcpWatchProc _ANSI_ARGS_((ClientData instanceData,
+		            int mask));
+static int		TtyParseMode _ANSI_ARGS_((Tcl_Interp *interp,
+			    CONST char *mode, int *speedPtr, int *parityPtr,
+			    int *dataPtr, int *stopPtr));
+static void		TtyGetAttributes _ANSI_ARGS_((int fd,
+			    TtyAttrs *ttyPtr));
+static int		TtyGetOptionProc _ANSI_ARGS_((ClientData instanceData,
+			    Tcl_Interp *interp, char *optionName,
+			    Tcl_DString *dsPtr));
+static void		TtyInit _ANSI_ARGS_((int fd));
+static void		TtySetAttributes _ANSI_ARGS_((int fd,
+			    TtyAttrs *ttyPtr));
+static int		TtySetOptionProc _ANSI_ARGS_((ClientData instanceData,
+			    Tcl_Interp *interp, char *optionName, 
+			    char *value));
+static int		WaitForConnect _ANSI_ARGS_((TcpState *statePtr,
+		            int *errorCodePtr));
+
+/*
+ * This structure describes the channel type structure for file based IO:
+ */
+
+static Tcl_ChannelType fileChannelType = {
+    "file",				/* Type name. */
+    FileBlockModeProc,			/* Set blocking/nonblocking mode.*/
+    FileCloseProc,			/* Close proc. */
+    FileInputProc,			/* Input proc. */
+    FileOutputProc,			/* Output proc. */
+    FileSeekProc,			/* Seek proc. */
+    NULL,				/* Set option proc. */
+    NULL,				/* Get option proc. */
+    FileWatchProc,			/* Initialize notifier. */
+    FileGetHandleProc,			/* Get OS handles out of channel. */
+};
+
+/*
+ * This structure describes the channel type structure for serial IO.
+ * Note that this type is a subclass of the "file" type.
+ */
+
+static Tcl_ChannelType ttyChannelType = {
+    "tty",				/* Type name. */
+    FileBlockModeProc,			/* Set blocking/nonblocking mode.*/
+    FileCloseProc,			/* Close proc. */
+    FileInputProc,			/* Input proc. */
+    FileOutputProc,			/* Output proc. */
+    NULL,				/* Seek proc. */
+    TtySetOptionProc,			/* Set option proc. */
+    TtyGetOptionProc,			/* Get option proc. */
+    FileWatchProc,			/* Initialize notifier. */
+    FileGetHandleProc,			/* Get OS handles out of channel. */
+};
+
+/*
+ * This structure describes the channel type structure for TCP socket
+ * based IO:
+ */
+
+static Tcl_ChannelType tcpChannelType = {
+    "tcp",				/* Type name. */
+    TcpBlockModeProc,			/* Set blocking/nonblocking mode.*/
+    TcpCloseProc,			/* Close proc. */
+    TcpInputProc,			/* Input proc. */
+    TcpOutputProc,			/* Output proc. */
+    NULL,				/* Seek proc. */
+    NULL,				/* Set option proc. */
+    TcpGetOptionProc,			/* Get option proc. */
+    TcpWatchProc,			/* Initialize notifier. */
+    TcpGetHandleProc,			/* Get OS handles out of channel. */
+};
+
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileBlockModeProc --
+ *
+ *	Helper procedure to set blocking and nonblocking modes on a
+ *	file based channel. Invoked by generic IO level code.
+ *
+ * Results:
+ *	0 if successful, errno when failed.
+ *
+ * Side effects:
+ *	Sets the device into blocking or non-blocking mode.
+ *
+ *----------------------------------------------------------------------
+ */
+
+	/* ARGSUSED */
+static int
+FileBlockModeProc(instanceData, mode)
+    ClientData instanceData;		/* File state. */
+    int mode;				/* The mode to set. Can be one of
+                                         * TCL_MODE_BLOCKING or
+                                         * TCL_MODE_NONBLOCKING. */
+{
+    FileState *fsPtr = (FileState *) instanceData;
+    int curStatus;
+
+#ifndef USE_FIONBIO
+    curStatus = fcntl(fsPtr->fd, F_GETFL);
+    if (mode == TCL_MODE_BLOCKING) {
+	curStatus &= (~(O_NONBLOCK));
+    } else {
+	curStatus |= O_NONBLOCK;
+    }
+    if (fcntl(fsPtr->fd, F_SETFL, curStatus) < 0) {
+	return errno;
+    }
+    curStatus = fcntl(fsPtr->fd, F_GETFL);
+#else
+    if (mode == TCL_MODE_BLOCKING) {
+	curStatus = 0;
+    } else {
+	curStatus = 1;
+    }
+    if (ioctl(fsPtr->fd, (int) FIONBIO, &curStatus) < 0) {
+	return errno;
+    }
+#endif
+    return 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileInputProc --
+ *
+ *	This procedure is invoked from the generic IO level to read
+ *	input from a file based channel.
+ *
+ * Results:
+ *	The number of bytes read is returned or -1 on error. An output
+ *	argument contains a POSIX error code if an error occurs, or zero.
+ *
+ * Side effects:
+ *	Reads input from the input device of the channel.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+FileInputProc(instanceData, buf, toRead, errorCodePtr)
+    ClientData instanceData;		/* File state. */
+    char *buf;				/* Where to store data read. */
+    int toRead;				/* How much space is available
+                                         * in the buffer? */
+    int *errorCodePtr;			/* Where to store error code. */
+{
+    FileState *fsPtr = (FileState *) instanceData;
+    int bytesRead;			/* How many bytes were actually
+                                         * read from the input device? */
+
+    *errorCodePtr = 0;
+    
+    /*
+     * Assume there is always enough input available. This will block
+     * appropriately, and read will unblock as soon as a short read is
+     * possible, if the channel is in blocking mode. If the channel is
+     * nonblocking, the read will never block.
+     */
+
+    bytesRead = read(fsPtr->fd, buf, (size_t) toRead);
+    if (bytesRead > -1) {
+        return bytesRead;
+    }
+    *errorCodePtr = errno;
+    return -1;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileOutputProc--
+ *
+ *	This procedure is invoked from the generic IO level to write
+ *	output to a file channel.
+ *
+ * Results:
+ *	The number of bytes written is returned or -1 on error. An
+ *	output argument	contains a POSIX error code if an error occurred,
+ *	or zero.
+ *
+ * Side effects:
+ *	Writes output on the output device of the channel.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+FileOutputProc(instanceData, buf, toWrite, errorCodePtr)
+    ClientData instanceData;		/* File state. */
+    char *buf;				/* The data buffer. */
+    int toWrite;			/* How many bytes to write? */
+    int *errorCodePtr;			/* Where to store error code. */
+{
+    FileState *fsPtr = (FileState *) instanceData;
+    int written;
+
+    *errorCodePtr = 0;
+    written = write(fsPtr->fd, buf, (size_t) toWrite);
+    if (written > -1) {
+        return written;
+    }
+    *errorCodePtr = errno;
+    return -1;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileCloseProc --
+ *
+ *	This procedure is called from the generic IO level to perform
+ *	channel-type-specific cleanup when a file based channel is closed.
+ *
+ * Results:
+ *	0 if successful, errno if failed.
+ *
+ * Side effects:
+ *	Closes the device of the channel.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+FileCloseProc(instanceData, interp)
+    ClientData instanceData;	/* File state. */
+    Tcl_Interp *interp;		/* For error reporting - unused. */
+{
+    FileState *fsPtr = (FileState *) instanceData;
+    FileState **nextPtrPtr;
+    int errorCode = 0;
+
+    Tcl_DeleteFileHandler(fsPtr->fd);
+    if (!TclInExit()
+	    || ((fsPtr->fd != 0) && (fsPtr->fd != 1) && (fsPtr->fd != 2))) {
+	if (close(fsPtr->fd) < 0) {
+	    errorCode = errno;
+	}
+    }
+    for (nextPtrPtr = &firstFilePtr; (*nextPtrPtr) != NULL;
+	 nextPtrPtr = &((*nextPtrPtr)->nextPtr)) {
+	if ((*nextPtrPtr) == fsPtr) {
+	    (*nextPtrPtr) = fsPtr->nextPtr;
+	    break;
+	}
+    }
+    ckfree((char *) fsPtr);
+    return errorCode;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileSeekProc --
+ *
+ *	This procedure is called by the generic IO level to move the
+ *	access point in a file based channel.
+ *
+ * Results:
+ *	-1 if failed, the new position if successful. An output
+ *	argument contains the POSIX error code if an error occurred,
+ *	or zero.
+ *
+ * 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? Can be
+                                                 * one of SEEK_START,
+                                                 * SEEK_SET or SEEK_END. */
+    int *errorCodePtr;				/* To store error code. */
+{
+    FileState *fsPtr = (FileState *) instanceData;
+    int newLoc;
+
+    newLoc = lseek(fsPtr->fd, offset, mode);
+
+    *errorCodePtr = (newLoc == -1) ? errno : 0;
+    return newLoc;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileWatchProc --
+ *
+ *	Initialize the notifier to watch the fd from this channel.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Sets up the notifier so that a future event on the channel will
+ *	be seen by Tcl.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+FileWatchProc(instanceData, mask)
+    ClientData instanceData;		/* The file state. */
+    int mask;				/* Events of interest; an OR-ed
+                                         * combination of TCL_READABLE,
+                                         * TCL_WRITABLE and TCL_EXCEPTION. */
+{
+    FileState *fsPtr = (FileState *) instanceData;
+
+    /*
+     * Make sure we only register for events that are valid on this file.
+     * Note that we are passing Tcl_NotifyChannel directly to
+     * Tcl_CreateFileHandler with the channel pointer as the client data.
+     */
+
+    mask &= fsPtr->validMask;
+    if (mask) {
+	Tcl_CreateFileHandler(fsPtr->fd, mask,
+		(Tcl_FileProc *) Tcl_NotifyChannel,
+		(ClientData) fsPtr->channel);
+    } else {
+	Tcl_DeleteFileHandler(fsPtr->fd);
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileGetHandleProc --
+ *
+ *	Called from Tcl_GetChannelFile 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.  */
+{
+    FileState *fsPtr = (FileState *) instanceData;
+
+    if (direction & fsPtr->validMask) {
+	*handlePtr = (ClientData) fsPtr->fd;
+	return TCL_OK;
+    } else {
+	return TCL_ERROR;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TtySetOptionProc --
+ *
+ *	Sets an option on a channel.
+ *
+ * Results:
+ *	A standard Tcl result. Also sets interp->result on error if
+ *	interp is not NULL.
+ *
+ * Side effects:
+ *	May modify an option on a device.
+ *      Sets Error message if needed (by calling Tcl_BadChannelOption).
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int		
+TtySetOptionProc(instanceData, interp, optionName, value)
+    ClientData instanceData;	/* File state. */
+    Tcl_Interp *interp;		/* For error reporting - can be NULL. */
+    char *optionName;		/* Which option to set? */
+    char *value;		/* New value for option. */
+{
+    FileState *fsPtr = (FileState *) instanceData;
+    unsigned int len;
+    TtyAttrs tty;
+
+    len = strlen(optionName);
+    if ((len > 1) && (strncmp(optionName, "-mode", len) == 0)) {
+	if (TtyParseMode(interp, value, &tty.baud, &tty.parity, &tty.data,
+		&tty.stop) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	/*
+	 * system calls results should be checked there. -- dl
+	 */
+
+	TtySetAttributes(fsPtr->fd, &tty);
+	return TCL_OK;
+    } else {
+	return Tcl_BadChannelOption(interp, optionName, "mode");
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TtyGetOptionProc --
+ *
+ *	Gets a mode associated with an IO channel. If the optionName arg
+ *	is non NULL, retrieves the value of that option. If the optionName
+ *	arg is NULL, retrieves a list of alternating option names and
+ *	values for the given channel.
+ *
+ * Results:
+ *	A standard Tcl result. Also sets the supplied DString to the
+ *	string value of the option(s) returned.
+ *
+ * Side effects:
+ *	The string returned by this function is in static storage and
+ *	may be reused at any time subsequent to the call.
+ *      Sets Error message if needed (by calling Tcl_BadChannelOption).
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int		
+TtyGetOptionProc(instanceData, interp, optionName, dsPtr)
+    ClientData instanceData;	/* File state. */
+    Tcl_Interp *interp;		/* For error reporting - can be NULL. */
+    char *optionName;		/* Option to get. */
+    Tcl_DString *dsPtr;		/* Where to store value(s). */
+{
+    FileState *fsPtr = (FileState *) instanceData;
+    unsigned int len;
+    char buf[32];
+    TtyAttrs tty;
+
+    if (optionName == NULL) {
+	Tcl_DStringAppendElement(dsPtr, "-mode");
+	len = 0;
+    } else {
+	len = strlen(optionName);
+    }
+    if ((len == 0) || 
+	    ((len > 1) && (strncmp(optionName, "-mode", len) == 0))) {
+	TtyGetAttributes(fsPtr->fd, &tty);
+	sprintf(buf, "%d,%c,%d,%d", tty.baud, tty.parity, tty.data, tty.stop);
+	Tcl_DStringAppendElement(dsPtr, buf);
+	return TCL_OK;
+    } else {
+	return Tcl_BadChannelOption(interp, optionName, "mode");
+    }
+}
+
+#undef DIRECT_BAUD
+#ifdef B4800
+#   if (B4800 == 4800)
+#	define DIRECT_BAUD
+#   endif
+#endif
+
+#ifdef DIRECT_BAUD
+#   define TtyGetSpeed(baud)   ((unsigned) (baud))
+#   define TtyGetBaud(speed)   ((int) (speed))
+#else
+
+static struct {int baud; unsigned long speed;} speeds[] = {
+#ifdef B0
+    {0, B0},
+#endif
+#ifdef B50
+    {50, B50},
+#endif
+#ifdef B75
+    {75, B75},
+#endif
+#ifdef B110
+    {110, B110},
+#endif
+#ifdef B134
+    {134, B134},
+#endif
+#ifdef B150
+    {150, B150},
+#endif
+#ifdef B200
+    {200, B200},
+#endif
+#ifdef B300
+    {300, B300},
+#endif
+#ifdef B600
+    {600, B600},
+#endif
+#ifdef B1200
+    {1200, B1200},
+#endif
+#ifdef B1800
+    {1800, B1800},
+#endif
+#ifdef B2400
+    {2400, B2400},
+#endif
+#ifdef B4800
+    {4800, B4800},
+#endif
+#ifdef B9600
+    {9600, B9600},
+#endif
+#ifdef B14400
+    {14400, B14400},
+#endif
+#ifdef B19200
+    {19200, B19200},
+#endif
+#ifdef EXTA
+    {19200, EXTA},
+#endif
+#ifdef B28800
+    {28800, B28800},
+#endif
+#ifdef B38400
+    {38400, B38400},
+#endif
+#ifdef EXTB
+    {38400, EXTB},
+#endif
+#ifdef B57600
+    {57600, B57600},
+#endif
+#ifdef _B57600
+    {57600, _B57600},
+#endif
+#ifdef B76800
+    {76800, B76800},
+#endif
+#ifdef B115200
+    {115200, B115200},
+#endif
+#ifdef _B115200
+    {115200, _B115200},
+#endif
+#ifdef B153600
+    {153600, B153600},
+#endif
+#ifdef B230400
+    {230400, B230400},
+#endif
+#ifdef B307200
+    {307200, B307200},
+#endif
+#ifdef B460800
+    {460800, B460800},
+#endif
+    {-1, 0}
+};
+
+/*
+ *---------------------------------------------------------------------------
+ *
+ * TtyGetSpeed --
+ *
+ *	Given a baud rate, get the mask value that should be stored in
+ *	the termios, termio, or sgttyb structure in order to select that
+ *	baud rate.
+ *
+ * Results:
+ *	As above.
+ *
+ * Side effects:
+ *	None.
+ *
+ *---------------------------------------------------------------------------
+ */
+
+static unsigned long
+TtyGetSpeed(baud)
+    int baud;			/* The baud rate to look up. */
+{
+    int bestIdx, bestDiff, i, diff;
+    
+    bestIdx = 0;
+    bestDiff = 1000000;
+    
+    /*
+     * If the baud rate does not correspond to one of the known mask values,
+     * choose the mask value whose baud rate is closest to the specified
+     * baud rate.
+     */
+
+    for (i = 0; speeds[i].baud >= 0; i++) {
+	diff = speeds[i].baud - baud;
+	if (diff < 0) {
+	    diff = -diff;
+	}
+	if (diff < bestDiff) {
+	    bestIdx = i;
+	    bestDiff = diff;
+	}
+    }
+    return speeds[bestIdx].speed;
+}
+
+/*
+ *---------------------------------------------------------------------------
+ *
+ * TtyGetBaud --
+ *
+ *	Given a speed mask value from a termios, termio, or sgttyb
+ *	structure, get the baus rate that corresponds to that mask value.
+ *
+ * Results:
+ *	As above.  If the mask value was not recognized, 0 is returned.
+ *
+ * Side effects:
+ *	None.
+ *
+ *---------------------------------------------------------------------------
+ */
+
+static int
+TtyGetBaud(speed)
+    unsigned long speed;	/* Speed mask value to look up. */
+{
+    int i;
+    
+    for (i = 0; speeds[i].baud >= 0; i++) {
+	if (speeds[i].speed == speed) {
+	    return speeds[i].baud;
+	}
+    }
+    return 0;
+}
+
+#endif	/* !DIRECT_BAUD */
+
+
+/*
+ *---------------------------------------------------------------------------
+ *
+ * TtyInit --
+ *
+ *	Given file descriptor that refers to a serial port, 
+ *	initialize the serial port to a set of sane values so that
+ *	Tcl can talk to a device located on the serial port.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Serial device initialized.
+ *
+ *---------------------------------------------------------------------------
+ */
+
+static void
+TtyInit(fd)
+    int fd;			/* Open file descriptor for serial port to
+				 * be initialized. */
+{
+#ifdef USE_TERMIOS
+    struct termios termios;
+
+    tcgetattr(fd, &termios);
+    termios.c_iflag = IGNBRK;
+    termios.c_oflag = 0;
+    termios.c_lflag = 0;
+    termios.c_cflag |= CREAD;
+    termios.c_cc[VMIN] = 60;
+    termios.c_cc[VTIME] = 2;
+    tcsetattr(fd, TCSANOW, &termios);
+#else	/* !USE_TERMIOS */
+#ifdef USE_TERMIO
+    struct termio termio;
+
+    ioctl(fd, TCGETA, &termio);
+    termio.c_iflag = IGNBRK;
+    termio.c_oflag = 0;
+    termio.c_lflag = 0;
+    termio.c_cflag |= CREAD;
+    termio.c_cc[VMIN] = 60;
+    termio.c_cc[VTIME] = 2;
+    ioctl(fd, TCSETAW, &termio);
+#else	/* !USE_TERMIO */
+#ifdef USE_SGTTY
+    struct sgttyb sgttyb;
+
+    ioctl(fd, TIOCGETP, &sgttyb);
+    sgttyb.sg_flags &= (EVENP | ODDP);
+    sgttyb.sg_flags |= RAW;
+    ioctl(fd, TIOCSETP, &sgttyb);
+#endif	/* USE_SGTTY */
+#endif	/* !USE_TERMIO */
+#endif	/* !USE_TERMIOS */
+}
+
+/*
+ *---------------------------------------------------------------------------
+ *
+ * TtyGetAttributes --
+ *
+ *	Get the current attributes of the specified serial device.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	None.
+ *
+ *---------------------------------------------------------------------------
+ */
+ 
+static void
+TtyGetAttributes(fd, ttyPtr)
+    int fd;			/* Open file descriptor for serial port to
+				 * be queried. */
+    TtyAttrs *ttyPtr;		/* Buffer filled with serial port
+				 * attributes. */
+{
+#ifdef USE_TERMIOS
+    int parity, data;
+    struct termios termios;
+
+    tcgetattr(fd, &termios);
+    ttyPtr->baud = TtyGetBaud(cfgetospeed(&termios));
+    
+    parity = 'n';
+#ifdef PAREXT
+    switch ((int) (termios.c_cflag & (PARENB | PARODD | PAREXT))) {
+	case PARENB		      : parity = 'e'; break;
+	case PARENB | PARODD	      :	parity = 'o'; break;
+	case PARENB |	       PAREXT : parity = 's'; break;
+	case PARENB | PARODD | PAREXT :	parity = 'm'; break;
+    }
+#else	/* !PAREXT */
+    switch ((int) (termios.c_cflag & (PARENB | PARODD))) {
+	case PARENB		      : parity = 'e'; break;
+	case PARENB | PARODD	      :	parity = 'o'; break;
+    }
+#endif	/* !PAREXT */
+    ttyPtr->parity = parity;
+
+    data = termios.c_cflag & CSIZE;
+    ttyPtr->data = (data == CS5) ? 5 : (data == CS6) ? 6 :
+	    (data == CS7) ? 7 : 8;
+
+    ttyPtr->stop = (termios.c_cflag & CSTOPB) ? 2 : 1;
+#else	/* !USE_TERMIOS */
+#ifdef USE_TERMIO
+    int parity, data;
+    struct termio termio;
+
+    ioctl(fd, TCGETA, &termio);
+    ttyPtr->baud = TtyGetBaud(termio.c_cflag & CBAUD);
+    parity = 'n';
+    switch (termio.c_cflag & (PARENB | PARODD | PAREXT)) {
+	case PARENB		      : parity = 'e'; break;
+	case PARENB | PARODD	      :	parity = 'o'; break;
+	case PARENB |	       PAREXT : parity = 's'; break;
+	case PARENB | PARODD | PAREXT :	parity = 'm'; break;
+    }
+    ttyPtr->parity = parity;
+
+    data = termio.c_cflag & CSIZE;
+    ttyPtr->data = (data == CS5) ? 5 : (data == CS6) ? 6 :
+	    (data == CS7) ? 7 : 8;
+
+    ttyPtr->stop = (termio.c_cflag & CSTOPB) ? 2 : 1;
+#else	/* !USE_TERMIO */
+#ifdef USE_SGTTY
+    int parity;
+    struct sgttyb sgttyb;
+
+    ioctl(fd, TIOCGETP, &sgttyb);
+    ttyPtr->baud = TtyGetBaud(sgttyb.sg_ospeed);
+    parity = 'n';
+    if (sgttyb.sg_flags & EVENP) {
+	parity = 'e';
+    } else if (sgttyb.sg_flags & ODDP) {
+	parity = 'o';
+    }
+    ttyPtr->parity = parity;
+    ttyPtr->data = (sgttyb.sg_flags & (EVENP | ODDP)) ? 7 : 8;
+    ttyPtr->stop = 1;
+#else	/* !USE_SGTTY */
+    ttyPtr->baud = 0;
+    ttyPtr->parity = 'n';
+    ttyPtr->data = 0;
+    ttyPtr->stop = 0;
+#endif	/* !USE_SGTTY */
+#endif	/* !USE_TERMIO */
+#endif	/* !USE_TERMIOS */
+}
+
+/*
+ *---------------------------------------------------------------------------
+ *
+ * TtySetAttributes --
+ *
+ *	Set the current attributes of the specified serial device. 
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	None.
+ *
+ *---------------------------------------------------------------------------
+ */
+ 
+static void
+TtySetAttributes(fd, ttyPtr)
+    int fd;			/* Open file descriptor for serial port to
+				 * be modified. */
+    TtyAttrs *ttyPtr;		/* Buffer containing new attributes for
+				 * serial port. */
+{
+#ifdef USE_TERMIOS
+    int parity, data, flag;
+    struct termios termios;
+
+    tcgetattr(fd, &termios);
+    cfsetospeed(&termios, TtyGetSpeed(ttyPtr->baud));
+    cfsetispeed(&termios, TtyGetSpeed(ttyPtr->baud));
+
+    flag = 0;
+    parity = ttyPtr->parity;
+    if (parity != 'n') {
+	flag |= PARENB;
+#ifdef PAREXT
+	termios.c_cflag &= ~PAREXT;
+	if ((parity == 'm') || (parity == 's')) {
+	    flag |= PAREXT;
+	}
+#endif
+	if ((parity == 'm') || (parity == 'o')) {
+	    flag |= PARODD;
+	}
+    }
+    data = ttyPtr->data;
+    flag |= (data == 5) ? CS5 : (data == 6) ? CS6 : (data == 7) ? CS7 : CS8;
+    if (ttyPtr->stop == 2) {
+	flag |= CSTOPB;
+    }
+
+    termios.c_cflag &= ~(PARENB | PARODD | CSIZE | CSTOPB);
+    termios.c_cflag |= flag;
+    tcsetattr(fd, TCSANOW, &termios);
+
+#else	/* !USE_TERMIOS */
+#ifdef USE_TERMIO
+    int parity, data, flag;
+    struct termio termio;
+
+    ioctl(fd, TCGETA, &termio);
+    termio.c_cflag &= ~CBAUD;
+    termio.c_cflag |= TtyGetSpeed(ttyPtr->baud);
+
+    flag = 0;
+    parity = ttyPtr->parity;
+    if (parity != 'n') {
+	flag |= PARENB;
+	if ((parity == 'm') || (parity == 's')) {
+	    flag |= PAREXT;
+	}
+	if ((parity == 'm') || (parity == 'o')) {
+	    flag |= PARODD;
+	}
+    }
+    data = ttyPtr->data;
+    flag |= (data == 5) ? CS5 : (data == 6) ? CS6 : (data == 7) ? CS7 : CS8;
+    if (ttyPtr->stop == 2) {
+	flag |= CSTOPB;
+    }
+
+    termio.c_cflag &= ~(PARENB | PARODD | PAREXT | CSIZE | CSTOPB);
+    termio.c_cflag |= flag;
+    ioctl(fd, TCSETAW, &termio);
+
+#else	/* !USE_TERMIO */
+#ifdef USE_SGTTY
+    int parity;
+    struct sgttyb sgttyb;
+
+    ioctl(fd, TIOCGETP, &sgttyb);
+    sgttyb.sg_ospeed = TtyGetSpeed(ttyPtr->baud);
+    sgttyb.sg_ispeed = TtyGetSpeed(ttyPtr->baud);
+
+    parity = ttyPtr->parity;
+    if (parity == 'e') {
+	sgttyb.sg_flags &= ~ODDP;
+	sgttyb.sg_flags |= EVENP;
+    } else if (parity == 'o') {
+	sgttyb.sg_flags &= ~EVENP;
+	sgttyb.sg_flags |= ODDP;
+    }
+    ioctl(fd, TIOCSETP, &sgttyb);
+#endif	/* USE_SGTTY */
+#endif	/* !USE_TERMIO */
+#endif	/* !USE_TERMIOS */
+}
+
+/*
+ *---------------------------------------------------------------------------
+ *
+ * TtyParseMode --
+ *
+ *	Parse the "-mode" argument to the fconfigure command.  The argument
+ *	is of the form baud,parity,data,stop.
+ *
+ * Results:
+ *	The return value is TCL_OK if the argument was successfully
+ *	parsed, TCL_ERROR otherwise.  If TCL_ERROR is returned, an
+ *	error message is left in interp->result (if interp is non-NULL).
+ *
+ * Side effects:
+ *	None.
+ *
+ *---------------------------------------------------------------------------
+ */
+ 
+static int
+TtyParseMode(interp, mode, speedPtr, parityPtr, dataPtr, stopPtr)
+    Tcl_Interp *interp;		/* If non-NULL, interp for error return. */
+    CONST char *mode;		/* Mode string to be parsed. */
+    int *speedPtr;		/* Filled with baud rate from mode string. */
+    int *parityPtr;		/* Filled with parity from mode string. */
+    int *dataPtr;		/* Filled with data bits from mode string. */
+    int *stopPtr;		/* Filled with stop bits from mode string. */
+{
+    int i, end;
+    char parity;
+    static char *bad = "bad value for -mode";
+
+    i = sscanf(mode, "%d,%c,%d,%d%n", speedPtr, &parity, dataPtr,
+	    stopPtr, &end);
+    if ((i != 4) || (mode[end] != '\0')) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, bad, ": should be baud,parity,data,stop",
+		    NULL);
+	}
+	return TCL_ERROR;
+    }
+    if (strchr("noems", parity) == NULL) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, bad,
+		    " parity: should be n, o, e, m, or s", NULL);
+	}
+	return TCL_ERROR;
+    }
+    *parityPtr = parity;
+    if ((*dataPtr < 5) || (*dataPtr > 8)) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, bad, " data: should be 5, 6, 7, or 8",
+		    NULL);
+	}
+	return TCL_ERROR;
+    }
+    if ((*stopPtr < 0) || (*stopPtr > 2)) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, bad, " stop: should be 1 or 2", NULL);
+	}
+	return TCL_ERROR;
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_OpenFileChannel --
+ *
+ *	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 and an error message is
+ *	left in interp->result if interp is not NULL.
+ *
+ * Side effects:
+ *	May open the channel and may cause creation of a file on the
+ *	file system.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Channel
+Tcl_OpenFileChannel(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? */
+{
+    int fd, seekFlag, mode, channelPermissions;
+    FileState *fsPtr;
+    char *nativeName, channelName[20];
+    Tcl_DString buffer;
+    Tcl_ChannelType *channelTypePtr;
+
+    mode = TclGetOpenMode(interp, modeString, &seekFlag);
+    if (mode == -1) {
+        return NULL;
+    }
+    switch (mode & (O_RDONLY | O_WRONLY | O_RDWR)) {
+	case O_RDONLY:
+	    channelPermissions = TCL_READABLE;
+	    break;
+	case O_WRONLY:
+	    channelPermissions = TCL_WRITABLE;
+	    break;
+	case O_RDWR:
+	    channelPermissions = (TCL_READABLE | TCL_WRITABLE);
+	    break;
+	default:
+            /*
+             * This may occurr if modeString was "", for example.
+             */
+	    panic("Tcl_OpenFileChannel: invalid mode value");
+	    return NULL;
+    }
+
+    nativeName = Tcl_TranslateFileName(interp, fileName, &buffer);
+    if (nativeName == NULL) {
+	return NULL;
+    }
+    fd = open(nativeName, mode, permissions);
+
+    /*
+     * If nativeName is not NULL, the buffer is valid and we must free
+     * the storage.
+     */
+    
+    Tcl_DStringFree(&buffer);
+
+    if (fd < 0) {
+        if (interp != (Tcl_Interp *) NULL) {
+            Tcl_AppendResult(interp, "couldn't open \"", fileName, "\": ",
+                    Tcl_PosixError(interp), (char *) NULL);
+        }
+        return NULL;
+    }
+
+    /*
+     * Set close-on-exec flag on the fd so that child processes will not
+     * inherit this fd.
+     */
+  
+    fcntl(fd, F_SETFD, FD_CLOEXEC);
+    
+    sprintf(channelName, "file%d", fd);
+    
+    fsPtr = (FileState *) ckalloc((unsigned) sizeof(FileState));
+    fsPtr->nextPtr = firstFilePtr;
+    firstFilePtr = fsPtr;
+    fsPtr->validMask = channelPermissions | TCL_EXCEPTION;
+    fsPtr->fd = fd;
+    
+    if (isatty(fd)) {
+	/*
+	 * Initialize the serial port to a set of sane parameters.
+	 * Especially important if the remote device is set to echo and
+	 * the serial port driver was also set to echo -- as soon as a char
+	 * were sent to the serial port, the remote device would echo it,
+	 * then the serial driver would echo it back to the device, etc.
+	 */
+	 
+	TtyInit(fd);
+	channelTypePtr = &ttyChannelType;
+    } else {
+	channelTypePtr = &fileChannelType;
+    }
+
+    fsPtr->channel = Tcl_CreateChannel(channelTypePtr, channelName,
+	    (ClientData) fsPtr, channelPermissions);
+
+    if (seekFlag) {
+        if (Tcl_Seek(fsPtr->channel, 0, SEEK_END) < 0) {
+            if (interp != (Tcl_Interp *) NULL) {
+                Tcl_AppendResult(interp, "couldn't seek to end of file on \"",
+                        channelName, "\": ", Tcl_PosixError(interp), NULL);
+            }
+            Tcl_Close(NULL, fsPtr->channel);
+            return NULL;
+        }
+    }
+
+    if (channelTypePtr == &ttyChannelType) {
+	/*
+	 * Gotcha.  Most modems need a "\r" at the end of the command
+	 * sequence.  If you just send "at\n", the modem will not respond
+	 * with "OK" because it never got a "\r" to actually invoke the
+	 * command.  So, by default, newlines are translated to "\r\n" on
+	 * output to avoid "bug" reports that the serial port isn't working.
+	 */
+	 
+	if (Tcl_SetChannelOption(interp, fsPtr->channel, "-translation",
+		"auto crlf") != TCL_OK) {
+	    Tcl_Close(NULL, fsPtr->channel);
+	    return NULL;
+	}
+    }
+
+    return fsPtr->channel;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_MakeFileChannel --
+ *
+ *	Makes a Tcl_Channel from an existing OS level file handle.
+ *
+ * Results:
+ *	The Tcl_Channel created around the preexisting OS level file handle.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Channel
+Tcl_MakeFileChannel(handle, mode)
+    ClientData handle;		/* OS level handle. */
+    int mode;			/* ORed combination of TCL_READABLE and
+                                 * TCL_WRITABLE to indicate file mode. */
+{
+    FileState *fsPtr;
+    char channelName[20];
+    int fd = (int) handle;
+
+    if (mode == 0) {
+        return NULL;
+    }
+
+    sprintf(channelName, "file%d", fd);
+
+    /*
+     * Look to see if a channel with this fd and the same mode already exists.
+     * If the fd is used, but the mode doesn't match, return NULL.
+     */
+    
+    for (fsPtr = firstFilePtr; fsPtr != NULL; fsPtr = fsPtr->nextPtr) {
+	if (fsPtr->fd == fd) {
+	    return (mode == fsPtr->validMask) ? fsPtr->channel : NULL;
+	}
+    }
+
+    fsPtr = (FileState *) ckalloc((unsigned) sizeof(FileState));
+    fsPtr->nextPtr = firstFilePtr;
+    firstFilePtr = fsPtr;
+    fsPtr->fd = fd;
+    fsPtr->validMask = mode | TCL_EXCEPTION;
+    fsPtr->channel = Tcl_CreateChannel(&fileChannelType, channelName,
+            (ClientData) fsPtr, mode);
+    
+    return fsPtr->channel;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TcpBlockModeProc --
+ *
+ *	This procedure is invoked by the generic IO level to set blocking
+ *	and nonblocking mode on a TCP socket based channel.
+ *
+ * Results:
+ *	0 if successful, errno when failed.
+ *
+ * Side effects:
+ *	Sets the device into blocking or nonblocking mode.
+ *
+ *----------------------------------------------------------------------
+ */
+
+	/* ARGSUSED */
+static int
+TcpBlockModeProc(instanceData, mode)
+    ClientData instanceData;		/* Socket state. */
+    int mode;				/* The mode to set. Can be one of
+                                         * TCL_MODE_BLOCKING or
+                                         * TCL_MODE_NONBLOCKING. */
+{
+    TcpState *statePtr = (TcpState *) instanceData;
+    int setting;
+    
+#ifndef	USE_FIONBIO
+    setting = fcntl(statePtr->fd, F_GETFL);
+    if (mode == TCL_MODE_BLOCKING) {
+        statePtr->flags &= (~(TCP_ASYNC_SOCKET));
+        setting &= (~(O_NONBLOCK));
+    } else {
+        statePtr->flags |= TCP_ASYNC_SOCKET;
+        setting |= O_NONBLOCK;
+    }
+    if (fcntl(statePtr->fd, F_SETFL, setting) < 0) {
+        return errno;
+    }
+#endif
+
+#ifdef	USE_FIONBIO
+    if (mode == TCL_MODE_BLOCKING) {
+        statePtr->flags &= (~(TCP_ASYNC_SOCKET));
+        setting = 0;
+        if (ioctl(statePtr->fd, (int) FIONBIO, &setting) == -1) {
+            return errno;
+        }
+    } else {
+        statePtr->flags |= TCP_ASYNC_SOCKET;
+        setting = 1;
+        if (ioctl(statePtr->fd, (int) FIONBIO, &setting) == -1) {
+            return errno;
+        }
+    }
+#endif
+
+    return 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * WaitForConnect --
+ *
+ *	Waits for a connection on an asynchronously opened socket to
+ *	be completed.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The socket is connected after this function returns.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+WaitForConnect(statePtr, errorCodePtr)
+    TcpState *statePtr;		/* State of the socket. */
+    int *errorCodePtr;		/* Where to store errors? */
+{
+    int timeOut;		/* How long to wait. */
+    int state;			/* Of calling TclWaitForFile. */
+    int flags;			/* fcntl flags for the socket. */
+
+    /*
+     * If an asynchronous connect is in progress, attempt to wait for it
+     * to complete before reading.
+     */
+    
+    if (statePtr->flags & TCP_ASYNC_CONNECT) {
+        if (statePtr->flags & TCP_ASYNC_SOCKET) {
+            timeOut = 0;
+        } else {
+            timeOut = -1;
+        }
+        errno = 0;
+        state = TclUnixWaitForFile(statePtr->fd,
+		TCL_WRITABLE | TCL_EXCEPTION, timeOut);
+        if (!(statePtr->flags & TCP_ASYNC_SOCKET)) {
+#ifndef	USE_FIONBIO
+            flags = fcntl(statePtr->fd, F_GETFL);
+            flags &= (~(O_NONBLOCK));
+            (void) fcntl(statePtr->fd, F_SETFL, flags);
+#endif
+
+#ifdef	USE_FIONBIO
+            flags = 0;
+            (void) ioctl(statePtr->fd, FIONBIO, &flags);
+#endif
+        }
+        if (state & TCL_EXCEPTION) {
+            return -1;
+        }
+        if (state & TCL_WRITABLE) {
+            statePtr->flags &= (~(TCP_ASYNC_CONNECT));
+        } else if (timeOut == 0) {
+            *errorCodePtr = errno = EWOULDBLOCK;
+            return -1;
+        }
+    }
+    return 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TcpInputProc --
+ *
+ *	This procedure is invoked by the generic IO level to read input
+ *	from a TCP socket based channel.
+ *
+ *	NOTE: We cannot share code with FilePipeInputProc because here
+ *	we must use recv to obtain the input from the channel, not read.
+ *
+ * Results:
+ *	The number of bytes read is returned or -1 on error. An output
+ *	argument contains the POSIX error code on error, or zero if no
+ *	error occurred.
+ *
+ * Side effects:
+ *	Reads input from the input device of the channel.
+ *
+ *----------------------------------------------------------------------
+ */
+
+	/* ARGSUSED */
+static int
+TcpInputProc(instanceData, buf, bufSize, errorCodePtr)
+    ClientData instanceData;		/* Socket state. */
+    char *buf;				/* Where to store data read. */
+    int bufSize;			/* How much space is available
+                                         * in the buffer? */
+    int *errorCodePtr;			/* Where to store error code. */
+{
+    TcpState *statePtr = (TcpState *) instanceData;
+    int bytesRead, state;
+
+    *errorCodePtr = 0;
+    state = WaitForConnect(statePtr, errorCodePtr);
+    if (state != 0) {
+        return -1;
+    }
+    bytesRead = recv(statePtr->fd, buf, bufSize, 0);
+    if (bytesRead > -1) {
+        return bytesRead;
+    }
+    if (errno == ECONNRESET) {
+
+        /*
+         * Turn ECONNRESET into a soft EOF condition.
+         */
+        
+        return 0;
+    }
+    *errorCodePtr = errno;
+    return -1;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TcpOutputProc --
+ *
+ *	This procedure is invoked by the generic IO level to write output
+ *	to a TCP socket based channel.
+ *
+ *	NOTE: We cannot share code with FilePipeOutputProc because here
+ *	we must use send, not write, to get reliable error reporting.
+ *
+ * Results:
+ *	The number of bytes written is returned. An output argument is
+ *	set to a POSIX error code if an error occurred, or zero.
+ *
+ * Side effects:
+ *	Writes output on the output device of the channel.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+TcpOutputProc(instanceData, buf, toWrite, errorCodePtr)
+    ClientData instanceData;		/* Socket state. */
+    char *buf;				/* The data buffer. */
+    int toWrite;			/* How many bytes to write? */
+    int *errorCodePtr;			/* Where to store error code. */
+{
+    TcpState *statePtr = (TcpState *) instanceData;
+    int written;
+    int state;				/* Of waiting for connection. */
+
+    *errorCodePtr = 0;
+    state = WaitForConnect(statePtr, errorCodePtr);
+    if (state != 0) {
+        return -1;
+    }
+    written = send(statePtr->fd, buf, toWrite, 0);
+    if (written > -1) {
+        return written;
+    }
+    *errorCodePtr = errno;
+    return -1;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TcpCloseProc --
+ *
+ *	This procedure is invoked by the generic IO level to perform
+ *	channel-type-specific cleanup when a TCP socket based channel
+ *	is closed.
+ *
+ * Results:
+ *	0 if successful, the value of errno if failed.
+ *
+ * Side effects:
+ *	Closes the socket of the channel.
+ *
+ *----------------------------------------------------------------------
+ */
+
+	/* ARGSUSED */
+static int
+TcpCloseProc(instanceData, interp)
+    ClientData instanceData;	/* The socket to close. */
+    Tcl_Interp *interp;		/* For error reporting - unused. */
+{
+    TcpState *statePtr = (TcpState *) instanceData;
+    int errorCode = 0;
+
+    /*
+     * Delete a file handler that may be active for this socket if this
+     * is a server socket - the file handler was created automatically
+     * by Tcl as part of the mechanism to accept new client connections.
+     * Channel handlers are already deleted in the generic IO channel
+     * closing code that called this function, so we do not have to
+     * delete them here.
+     */
+    
+    Tcl_DeleteFileHandler(statePtr->fd);
+
+    if (close(statePtr->fd) < 0) {
+	errorCode = errno;
+    }
+    ckfree((char *) statePtr);
+
+    return errorCode;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TcpGetOptionProc --
+ *
+ *	Computes an option value for a TCP socket based channel, or a
+ *	list of all options and their values.
+ *
+ *	Note: This code is based on code contributed by John Haxby.
+ *
+ * Results:
+ *	A standard Tcl result. The value of the specified option or a
+ *	list of all options and	their values is returned in the
+ *	supplied DString. Sets Error message if needed.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+TcpGetOptionProc(instanceData, interp, optionName, dsPtr)
+    ClientData instanceData;     /* Socket state. */
+    Tcl_Interp *interp;          /* For error reporting - can be NULL. */
+    char *optionName;	         /* Name of the option to
+				  * retrieve the value for, or
+				  * NULL to get all options and
+				  * their values. */
+    Tcl_DString *dsPtr;	         /* Where to store the computed
+				  * value; initialized by caller. */
+{
+    TcpState *statePtr = (TcpState *) instanceData;
+    struct sockaddr_in sockname;
+    struct sockaddr_in peername;
+    struct hostent *hostEntPtr;
+    int size = sizeof(struct sockaddr_in);
+    size_t len = 0;
+    char buf[128];
+
+    if (optionName != (char *) NULL) {
+        len = strlen(optionName);
+    }
+
+    if ((len == 0) ||
+            ((len > 1) && (optionName[1] == 'p') &&
+                    (strncmp(optionName, "-peername", len) == 0))) {
+        if (getpeername(statePtr->fd, (struct sockaddr *) &peername, &size)
+		>= 0) {
+            if (len == 0) {
+                Tcl_DStringAppendElement(dsPtr, "-peername");
+                Tcl_DStringStartSublist(dsPtr);
+            }
+            Tcl_DStringAppendElement(dsPtr, inet_ntoa(peername.sin_addr));
+            hostEntPtr = gethostbyaddr((char *) &(peername.sin_addr),
+                    sizeof(peername.sin_addr), AF_INET);
+            if (hostEntPtr != (struct hostent *) NULL) {
+                Tcl_DStringAppendElement(dsPtr, hostEntPtr->h_name);
+            } else {
+                Tcl_DStringAppendElement(dsPtr, inet_ntoa(peername.sin_addr));
+            }
+            sprintf(buf, "%d", ntohs(peername.sin_port));
+            Tcl_DStringAppendElement(dsPtr, buf);
+            if (len == 0) {
+                Tcl_DStringEndSublist(dsPtr);
+            } else {
+                return TCL_OK;
+            }
+        } else {
+            /*
+             * getpeername failed - but if we were asked for all the options
+             * (len==0), don't flag an error at that point because it could
+             * be an fconfigure request on a server socket. (which have
+             * no peer). same must be done on win&mac.
+             */
+
+            if (len) {
+                if (interp) {
+                    Tcl_AppendResult(interp, "can't get peername: ",
+                                     Tcl_PosixError(interp),
+                                     (char *) NULL);
+                }
+                return TCL_ERROR;
+            }
+        }
+    }
+
+    if ((len == 0) ||
+            ((len > 1) && (optionName[1] == 's') &&
+                    (strncmp(optionName, "-sockname", len) == 0))) {
+        if (getsockname(statePtr->fd, (struct sockaddr *) &sockname, &size)
+		>= 0) {
+            if (len == 0) {
+                Tcl_DStringAppendElement(dsPtr, "-sockname");
+                Tcl_DStringStartSublist(dsPtr);
+            }
+            Tcl_DStringAppendElement(dsPtr, inet_ntoa(sockname.sin_addr));
+            hostEntPtr = gethostbyaddr((char *) &(sockname.sin_addr),
+                    sizeof(sockname.sin_addr), AF_INET);
+            if (hostEntPtr != (struct hostent *) NULL) {
+                Tcl_DStringAppendElement(dsPtr, hostEntPtr->h_name);
+            } else {
+                Tcl_DStringAppendElement(dsPtr, inet_ntoa(sockname.sin_addr));
+            }
+            sprintf(buf, "%d", ntohs(sockname.sin_port));
+            Tcl_DStringAppendElement(dsPtr, buf);
+            if (len == 0) {
+                Tcl_DStringEndSublist(dsPtr);
+            } else {
+                return TCL_OK;
+            }
+        } else {
+	    if (interp) {
+		Tcl_AppendResult(interp, "can't get sockname: ",
+				 Tcl_PosixError(interp),
+				 (char *) NULL);
+	    }
+	    return TCL_ERROR;
+	}
+    }
+
+    if (len > 0) {
+        return Tcl_BadChannelOption(interp, optionName, "peername sockname");
+    }
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TcpWatchProc --
+ *
+ *	Initialize the notifier to watch the fd from this channel.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Sets up the notifier so that a future event on the channel will
+ *	be seen by Tcl.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+TcpWatchProc(instanceData, mask)
+    ClientData instanceData;		/* The socket state. */
+    int mask;				/* Events of interest; an OR-ed
+                                         * combination of TCL_READABLE,
+                                         * TCL_WRITABLE and TCL_EXCEPTION. */
+{
+    TcpState *statePtr = (TcpState *) instanceData;
+
+    if (mask) {
+	Tcl_CreateFileHandler(statePtr->fd, mask,
+		(Tcl_FileProc *) Tcl_NotifyChannel,
+		(ClientData) statePtr->channel);
+    } else {
+	Tcl_DeleteFileHandler(statePtr->fd);
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TcpGetHandleProc --
+ *
+ *	Called from Tcl_GetChannelFile to retrieve OS handles from inside
+ *	a TCP socket 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.
+ *
+ *----------------------------------------------------------------------
+ */
+
+	/* ARGSUSED */
+static int
+TcpGetHandleProc(instanceData, direction, handlePtr)
+    ClientData instanceData;	/* The socket state. */
+    int direction;		/* Not used. */
+    ClientData *handlePtr;	/* Where to store the handle.  */
+{
+    TcpState *statePtr = (TcpState *) instanceData;
+
+    *handlePtr = (ClientData)statePtr->fd;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * CreateSocket --
+ *
+ *	This function opens a new socket in client or server mode
+ *	and initializes the TcpState structure.
+ *
+ * Results:
+ *	Returns a new TcpState, or NULL with an error in interp->result,
+ *	if interp is not NULL.
+ *
+ * Side effects:
+ *	Opens a socket.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static TcpState *
+CreateSocket(interp, port, host, server, myaddr, myport, async)
+    Tcl_Interp *interp;		/* For error reporting; can be NULL. */
+    int port;			/* Port number to open. */
+    char *host;			/* Name of host on which to open port.
+				 * NULL implies INADDR_ANY */
+    int server;			/* 1 if socket should be a server socket,
+				 * else 0 for a client socket. */
+    char *myaddr;		/* Optional client-side address */
+    int myport;			/* Optional client-side port */
+    int async;			/* If nonzero and creating a client socket,
+                                 * attempt to do an async connect. Otherwise
+                                 * do a synchronous connect or bind. */
+{
+    int status, sock, asyncConnect, curState, origState;
+    struct sockaddr_in sockaddr;	/* socket address */
+    struct sockaddr_in mysockaddr;	/* Socket address for client */
+    TcpState *statePtr;
+
+    sock = -1;
+    origState = 0;
+    if (! CreateSocketAddress(&sockaddr, host, port)) {
+	goto addressError;
+    }
+    if ((myaddr != NULL || myport != 0) &&
+	    ! CreateSocketAddress(&mysockaddr, myaddr, myport)) {
+	goto addressError;
+    }
+
+    sock = socket(AF_INET, SOCK_STREAM, 0);
+    if (sock < 0) {
+	goto addressError;
+    }
+
+    /*
+     * Set the close-on-exec flag so that the socket will not get
+     * inherited by child processes.
+     */
+
+    fcntl(sock, F_SETFD, FD_CLOEXEC);
+    
+    /*
+     * Set kernel space buffering
+     */
+
+    TclSockMinimumBuffers(sock, SOCKET_BUFSIZE);
+
+    asyncConnect = 0;
+    status = 0;
+    if (server) {
+
+	/*
+	 * Set up to reuse server addresses automatically and bind to the
+	 * specified port.
+	 */
+    
+	status = 1;
+	(void) setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char *) &status,
+		sizeof(status));
+	status = bind(sock, (struct sockaddr *) &sockaddr,
+                sizeof(struct sockaddr));
+	if (status != -1) {
+	    status = listen(sock, SOMAXCONN);
+	} 
+    } else {
+	if (myaddr != NULL || myport != 0) { 
+	    curState = 1;
+	    (void) setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
+                    (char *) &curState, sizeof(curState));
+	    status = bind(sock, (struct sockaddr *) &mysockaddr,
+		    sizeof(struct sockaddr));
+	    if (status < 0) {
+		goto bindError;
+	    }
+	}
+
+	/*
+	 * Attempt to connect. The connect may fail at present with an
+	 * EINPROGRESS but at a later time it will complete. The caller
+	 * will set up a file handler on the socket if she is interested in
+	 * being informed when the connect completes.
+	 */
+
+        if (async) {
+#ifndef	USE_FIONBIO
+            origState = fcntl(sock, F_GETFL);
+            curState = origState | O_NONBLOCK;
+            status = fcntl(sock, F_SETFL, curState);
+#endif
+
+#ifdef	USE_FIONBIO
+            curState = 1;
+            status = ioctl(sock, FIONBIO, &curState);
+#endif            
+        } else {
+            status = 0;
+        }
+        if (status > -1) {
+            status = connect(sock, (struct sockaddr *) &sockaddr,
+                    sizeof(sockaddr));
+            if (status < 0) {
+                if (errno == EINPROGRESS) {
+                    asyncConnect = 1;
+                    status = 0;
+                }
+            }
+        }
+    }
+
+bindError:
+    if (status < 0) {
+        if (interp != NULL) {
+            Tcl_AppendResult(interp, "couldn't open socket: ",
+                    Tcl_PosixError(interp), (char *) NULL);
+        }
+        if (sock != -1) {
+            close(sock);
+        }
+        return NULL;
+    }
+
+    /*
+     * Allocate a new TcpState for this socket.
+     */
+
+    statePtr = (TcpState *) ckalloc((unsigned) sizeof(TcpState));
+    statePtr->flags = 0;
+    if (asyncConnect) {
+        statePtr->flags = TCP_ASYNC_CONNECT;
+    }
+    statePtr->fd = sock;
+    
+    return statePtr;
+
+addressError:
+    if (sock != -1) {
+        close(sock);
+    }
+    if (interp != NULL) {
+	Tcl_AppendResult(interp, "couldn't open socket: ",
+		Tcl_PosixError(interp), (char *) NULL);
+    }
+    return NULL;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * CreateSocketAddress --
+ *
+ *	This function initializes a sockaddr structure for a host and port.
+ *
+ * Results:
+ *	1 if the host was valid, 0 if the host could not be converted to
+ *	an IP address.
+ *
+ * Side effects:
+ *	Fills in the *sockaddrPtr structure.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+CreateSocketAddress(sockaddrPtr, host, port)
+    struct sockaddr_in *sockaddrPtr;	/* Socket address */
+    char *host;				/* Host.  NULL implies INADDR_ANY */
+    int port;				/* Port number */
+{
+    struct hostent *hostent;		/* Host database entry */
+    struct in_addr addr;		/* For 64/32 bit madness */
+
+    (void) memset((VOID *) sockaddrPtr, '\0', sizeof(struct sockaddr_in));
+    sockaddrPtr->sin_family = AF_INET;
+    sockaddrPtr->sin_port = htons((unsigned short) (port & 0xFFFF));
+    if (host == NULL) {
+	addr.s_addr = INADDR_ANY;
+    } else {
+        addr.s_addr = inet_addr(host);
+        if (addr.s_addr == -1) {
+            hostent = gethostbyname(host);
+            if (hostent != NULL) {
+                memcpy((VOID *) &addr,
+                        (VOID *) hostent->h_addr_list[0],
+                        (size_t) hostent->h_length);
+            } else {
+#ifdef	EHOSTUNREACH
+                errno = EHOSTUNREACH;
+#else
+#ifdef ENXIO
+                errno = ENXIO;
+#endif
+#endif
+                return 0;	/* error */
+            }
+        }
+    }
+        
+    /*
+     * NOTE: On 64 bit machines the assignment below is rumored to not
+     * do the right thing. Please report errors related to this if you
+     * observe incorrect behavior on 64 bit machines such as DEC Alphas.
+     * Should we modify this code to do an explicit memcpy?
+     */
+
+    sockaddrPtr->sin_addr.s_addr = addr.s_addr;
+    return 1;	/* Success. */
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_OpenTcpClient --
+ *
+ *	Opens a TCP client socket and creates a channel around it.
+ *
+ * Results:
+ *	The channel or NULL if failed.  An error message is returned
+ *	in the interpreter on failure.
+ *
+ * Side effects:
+ *	Opens a client socket and creates a new channel.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Channel
+Tcl_OpenTcpClient(interp, port, host, myaddr, myport, async)
+    Tcl_Interp *interp;			/* For error reporting; can be NULL. */
+    int port;				/* Port number to open. */
+    char *host;				/* Host on which to open port. */
+    char *myaddr;			/* Client-side address */
+    int myport;				/* Client-side port */
+    int async;				/* If nonzero, attempt to do an
+                                         * asynchronous connect. Otherwise
+                                         * we do a blocking connect. */
+{
+    TcpState *statePtr;
+    char channelName[20];
+
+    /*
+     * Create a new client socket and wrap it in a channel.
+     */
+
+    statePtr = CreateSocket(interp, port, host, 0, myaddr, myport, async);
+    if (statePtr == NULL) {
+	return NULL;
+    }
+
+    statePtr->acceptProc = NULL;
+    statePtr->acceptProcData = (ClientData) NULL;
+
+    sprintf(channelName, "sock%d", statePtr->fd);
+
+    statePtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
+            (ClientData) statePtr, (TCL_READABLE | TCL_WRITABLE));
+    if (Tcl_SetChannelOption(interp, statePtr->channel, "-translation",
+	    "auto crlf") == TCL_ERROR) {
+        Tcl_Close((Tcl_Interp *) NULL, statePtr->channel);
+        return NULL;
+    }
+    return statePtr->channel;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_MakeTcpClientChannel --
+ *
+ *	Creates a Tcl_Channel from an existing client TCP socket.
+ *
+ * Results:
+ *	The Tcl_Channel wrapped around the preexisting TCP socket.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Channel
+Tcl_MakeTcpClientChannel(sock)
+    ClientData sock;		/* The socket to wrap up into a channel. */
+{
+    TcpState *statePtr;
+    char channelName[20];
+
+    statePtr = (TcpState *) ckalloc((unsigned) sizeof(TcpState));
+    statePtr->fd = (int) sock;
+    statePtr->acceptProc = NULL;
+    statePtr->acceptProcData = (ClientData) NULL;
+
+    sprintf(channelName, "sock%d", statePtr->fd);
+    
+    statePtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
+            (ClientData) statePtr, (TCL_READABLE | TCL_WRITABLE));
+    if (Tcl_SetChannelOption((Tcl_Interp *) NULL, statePtr->channel,
+	    "-translation", "auto crlf") == TCL_ERROR) {
+        Tcl_Close((Tcl_Interp *) NULL, statePtr->channel);
+        return NULL;
+    }
+    return statePtr->channel;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_OpenTcpServer --
+ *
+ *	Opens a TCP server socket and creates a channel around it.
+ *
+ * Results:
+ *	The channel or NULL if failed. If an error occurred, an
+ *	error message is left in interp->result if interp is
+ *	not NULL.
+ *
+ * Side effects:
+ *	Opens a server socket and creates a new channel.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Channel
+Tcl_OpenTcpServer(interp, port, myHost, acceptProc, acceptProcData)
+    Tcl_Interp *interp;			/* For error reporting - may be
+                                         * NULL. */
+    int port;				/* Port number to open. */
+    char *myHost;			/* Name of local host. */
+    Tcl_TcpAcceptProc *acceptProc;	/* Callback for accepting connections
+                                         * from new clients. */
+    ClientData acceptProcData;		/* Data for the callback. */
+{
+    TcpState *statePtr;
+    char channelName[20];
+
+    /*
+     * Create a new client socket and wrap it in a channel.
+     */
+
+    statePtr = CreateSocket(interp, port, myHost, 1, NULL, 0, 0);
+    if (statePtr == NULL) {
+	return NULL;
+    }
+
+    statePtr->acceptProc = acceptProc;
+    statePtr->acceptProcData = acceptProcData;
+
+    /*
+     * Set up the callback mechanism for accepting connections
+     * from new clients.
+     */
+
+    Tcl_CreateFileHandler(statePtr->fd, TCL_READABLE, TcpAccept,
+            (ClientData) statePtr);
+    sprintf(channelName, "sock%d", statePtr->fd);
+    statePtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
+            (ClientData) statePtr, 0);
+    return statePtr->channel;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TcpAccept --
+ *	Accept a TCP socket connection.  This is called by the event loop.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Creates a new connection socket. Calls the registered callback
+ *	for the connection acceptance mechanism.
+ *
+ *----------------------------------------------------------------------
+ */
+
+	/* ARGSUSED */
+static void
+TcpAccept(data, mask)
+    ClientData data;			/* Callback token. */
+    int mask;				/* Not used. */
+{
+    TcpState *sockState;		/* Client data of server socket. */
+    int newsock;			/* The new client socket */
+    TcpState *newSockState;		/* State for new socket. */
+    struct sockaddr_in addr;		/* The remote address */
+    int len;				/* For accept interface */
+    char channelName[20];
+
+    sockState = (TcpState *) data;
+
+    len = sizeof(struct sockaddr_in);
+    newsock = accept(sockState->fd, (struct sockaddr *)&addr, &len);
+    if (newsock < 0) {
+        return;
+    }
+
+    /*
+     * Set close-on-exec flag to prevent the newly accepted socket from
+     * being inherited by child processes.
+     */
+
+    (void) fcntl(newsock, F_SETFD, FD_CLOEXEC);
+    
+    newSockState = (TcpState *) ckalloc((unsigned) sizeof(TcpState));
+
+    newSockState->flags = 0;
+    newSockState->fd = newsock;
+    newSockState->acceptProc = (Tcl_TcpAcceptProc *) NULL;
+    newSockState->acceptProcData = (ClientData) NULL;
+        
+    sprintf(channelName, "sock%d", newsock);
+    newSockState->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
+	    (ClientData) newSockState, (TCL_READABLE | TCL_WRITABLE));
+
+    Tcl_SetChannelOption((Tcl_Interp *) NULL, newSockState->channel,
+	    "-translation", "auto crlf");
+
+    if (sockState->acceptProc != (Tcl_TcpAcceptProc *) NULL) {
+	(sockState->acceptProc) (sockState->acceptProcData,
+		newSockState->channel, inet_ntoa(addr.sin_addr),
+		ntohs(addr.sin_port));
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclGetDefaultStdChannel --
+ *
+ *	Creates channels for standard input, standard output or standard
+ *	error output if they do not already exist.
+ *
+ * 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
+TclGetDefaultStdChannel(type)
+    int type;			/* One of TCL_STDIN, TCL_STDOUT, TCL_STDERR. */
+{
+    Tcl_Channel channel = NULL;
+    int fd = 0;			/* Initializations needed to prevent */
+    int mode = 0;		/* compiler warning (used before set). */
+    char *bufMode = NULL;
+
+    switch (type) {
+        case TCL_STDIN:
+            if ((lseek(0, (off_t) 0, SEEK_CUR) == -1) &&
+                    (errno == EBADF)) {
+                return (Tcl_Channel) NULL;
+            }
+	    fd = 0;
+	    mode = TCL_READABLE;
+            bufMode = "line";
+            break;
+        case TCL_STDOUT:
+            if ((lseek(1, (off_t) 0, SEEK_CUR) == -1) &&
+                    (errno == EBADF)) {
+                return (Tcl_Channel) NULL;
+            }
+	    fd = 1;
+	    mode = TCL_WRITABLE;
+            bufMode = "line";
+            break;
+        case TCL_STDERR:
+            if ((lseek(2, (off_t) 0, SEEK_CUR) == -1) &&
+                    (errno == EBADF)) {
+                return (Tcl_Channel) NULL;
+            }
+	    fd = 2;
+	    mode = TCL_WRITABLE;
+	    bufMode = "none";
+            break;
+	default:
+	    panic("TclGetDefaultStdChannel: Unexpected channel type");
+	    break;
+    }
+
+    channel = Tcl_MakeFileChannel((ClientData) fd, mode);
+
+    /*
+     * Set up the normal channel options for stdio handles.
+     */
+
+    Tcl_SetChannelOption(NULL, channel, "-translation", "auto");
+    Tcl_SetChannelOption(NULL, channel, "-buffering", bufMode);
+    return channel;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetOpenFile --
+ *
+ *	Given a name of a channel registered in the given interpreter,
+ *	returns a FILE * for it.
+ *
+ * Results:
+ *	A standard Tcl result. If the channel is registered in the given
+ *	interpreter and it is managed by the "file" channel driver, and
+ *	it is open for the requested mode, then the output parameter
+ *	filePtr is set to a FILE * for the underlying file. On error, the
+ *	filePtr is not set, TCL_ERROR is returned and an error message is
+ *	left in interp->result.
+ *
+ * Side effects:
+ *	May invoke fdopen to create the FILE * for the requested file.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetOpenFile(interp, string, forWriting, checkUsage, filePtr)
+    Tcl_Interp *interp;		/* Interpreter in which to find file. */
+    char *string;		/* String that identifies file. */
+    int forWriting;		/* 1 means the file is going to be used
+				 * for writing, 0 means for reading. */
+    int checkUsage;		/* 1 means verify that the file was opened
+				 * in a mode that allows the access specified
+				 * by "forWriting". Ignored, we always
+                                 * check that the channel is open for the
+                                 * requested mode. */
+    ClientData *filePtr;	/* Store pointer to FILE structure here. */
+{
+    Tcl_Channel chan;
+    int chanMode;
+    Tcl_ChannelType *chanTypePtr;
+    ClientData data;
+    int fd;
+    FILE *f;
+    
+    chan = Tcl_GetChannel(interp, string, &chanMode);
+    if (chan == (Tcl_Channel) NULL) {
+        return TCL_ERROR;
+    }
+    if ((forWriting) && ((chanMode & TCL_WRITABLE) == 0)) {
+        Tcl_AppendResult(interp,
+                "\"", string, "\" wasn't opened for writing", (char *) NULL);
+        return TCL_ERROR;
+    } else if ((!(forWriting)) && ((chanMode & TCL_READABLE) == 0)) {
+        Tcl_AppendResult(interp,
+                "\"", string, "\" wasn't opened for reading", (char *) NULL);
+        return TCL_ERROR;
+    }
+
+    /*
+     * We allow creating a FILE * out of file based, pipe based and socket
+     * based channels. We currently do not allow any other channel types,
+     * because it is likely that stdio will not know what to do with them.
+     */
+
+    chanTypePtr = Tcl_GetChannelType(chan);
+    if ((chanTypePtr == &fileChannelType) || (chanTypePtr == &tcpChannelType)
+	    || (strcmp(chanTypePtr->typeName, "pipe") == 0)) {
+        if (Tcl_GetChannelHandle(chan,
+		(forWriting ? TCL_WRITABLE : TCL_READABLE),
+		(ClientData*) &data) == TCL_OK) {
+	    fd = (int) data;
+
+	    /*
+	     * The call to fdopen below is probably dangerous, since it will
+	     * truncate an existing file if the file is being opened
+	     * for writing....
+	     */
+        
+	    f = fdopen(fd, (forWriting ? "w" : "r"));
+	    if (f == NULL) {
+		Tcl_AppendResult(interp, "cannot get a FILE * for \"", string,
+			"\"", (char *) NULL);
+		return TCL_ERROR;
+	    }
+	    *filePtr = (ClientData) f;
+	    return TCL_OK;
+	}
+    }
+
+    Tcl_AppendResult(interp, "\"", string,
+            "\" cannot be used to get a FILE *", (char *) NULL);
+    return TCL_ERROR;        
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclUnixWaitForFile --
+ *
+ *	This procedure waits synchronously for a file to become readable
+ *	or writable, with an optional timeout.
+ *
+ * Results:
+ *	The return value is an OR'ed combination of TCL_READABLE,
+ *	TCL_WRITABLE, and TCL_EXCEPTION, indicating the conditions
+ *	that are present on file at the time of the return.  This
+ *	procedure will not return until either "timeout" milliseconds
+ *	have elapsed or at least one of the conditions given by mask
+ *	has occurred for file (a return value of 0 means that a timeout
+ *	occurred).  No normal events will be serviced during the
+ *	execution of this procedure.
+ *
+ * Side effects:
+ *	Time passes.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclUnixWaitForFile(fd, mask, timeout)
+    int fd;			/* Handle for file on which to wait. */
+    int mask;			/* What to wait for: OR'ed combination of
+				 * TCL_READABLE, TCL_WRITABLE, and
+				 * TCL_EXCEPTION. */
+    int timeout;		/* Maximum amount of time to wait for one
+				 * of the conditions in mask to occur, in
+				 * milliseconds.  A value of 0 means don't
+				 * wait at all, and a value of -1 means
+				 * wait forever. */
+{
+    Tcl_Time abortTime, now;
+    struct timeval blockTime, *timeoutPtr;
+    int index, bit, numFound, result = 0;
+    static fd_mask readyMasks[3*MASK_SIZE];
+				/* This array reflects the readable/writable
+				 * conditions that were found to exist by the
+				 * last call to select. */
+
+    /*
+     * If there is a non-zero finite timeout, compute the time when
+     * we give up.
+     */
+
+    if (timeout > 0) {
+	TclpGetTime(&now);
+	abortTime.sec = now.sec + timeout/1000;
+	abortTime.usec = now.usec + (timeout%1000)*1000;
+	if (abortTime.usec >= 1000000) {
+	    abortTime.usec -= 1000000;
+	    abortTime.sec += 1;
+	}
+	timeoutPtr = &blockTime;
+    } else if (timeout == 0) {
+	timeoutPtr = &blockTime;
+	blockTime.tv_sec = 0;
+	blockTime.tv_usec = 0;
+    } else {
+	timeoutPtr = NULL;
+    }
+
+    /*
+     * Initialize the ready masks and compute the mask offsets.
+     */
+
+    if (fd >= FD_SETSIZE) {
+	panic("TclWaitForFile can't handle file id %d", fd);
+    }
+    memset((VOID *) readyMasks, 0, 3*MASK_SIZE*sizeof(fd_mask));
+    index = fd/(NBBY*sizeof(fd_mask));
+    bit = 1 << (fd%(NBBY*sizeof(fd_mask)));
+    
+    /*
+     * Loop in a mini-event loop of our own, waiting for either the
+     * file to become ready or a timeout to occur.
+     */
+
+    while (1) {
+	if (timeout > 0) {
+	    blockTime.tv_sec = abortTime.sec - now.sec;
+	    blockTime.tv_usec = abortTime.usec - now.usec;
+	    if (blockTime.tv_usec < 0) {
+		blockTime.tv_sec -= 1;
+		blockTime.tv_usec += 1000000;
+	    }
+	    if (blockTime.tv_sec < 0) {
+		blockTime.tv_sec = 0;
+		blockTime.tv_usec = 0;
+	    }
+	}
+	
+	/*
+	 * Set the appropriate bit in the ready masks for the fd.
+	 */
+
+	if (mask & TCL_READABLE) {
+	    readyMasks[index] |= bit;
+	}
+	if (mask & TCL_WRITABLE) {
+	    (readyMasks+MASK_SIZE)[index] |= bit;
+	}
+	if (mask & TCL_EXCEPTION) {
+	    (readyMasks+2*(MASK_SIZE))[index] |= bit;
+	}
+
+	/*
+	 * Wait for the event or a timeout.
+	 */
+
+	numFound = select(fd+1, (SELECT_MASK *) &readyMasks[0],
+		(SELECT_MASK *) &readyMasks[MASK_SIZE],
+		(SELECT_MASK *) &readyMasks[2*MASK_SIZE], timeoutPtr);
+	if (numFound == 1) {
+	    if (readyMasks[index] & bit) {
+		result |= TCL_READABLE;
+	    }
+	    if ((readyMasks+MASK_SIZE)[index] & bit) {
+		result |= TCL_WRITABLE;
+	    }
+	    if ((readyMasks+2*(MASK_SIZE))[index] & bit) {
+		result |= TCL_EXCEPTION;
+	    }
+	    result &= mask;
+	    if (result) {
+		break;
+	    }
+	}
+	if (timeout == 0) {
+	    break;
+	}
+
+	/*
+	 * The select returned early, so we need to recompute the timeout.
+	 */
+
+	TclpGetTime(&now);
+	if ((abortTime.sec < now.sec)
+		|| ((abortTime.sec == now.sec)
+		&& (abortTime.usec <= now.usec))) {
+	    break;
+	}
+    }
+    return result;
+}