/*
* tclIOGT.c --
*
* Implements a generic transformation exposing the underlying API at the
* script level. Contributed by Andreas Kupries.
*
* Copyright (c) 2000 Ajuba Solutions
* Copyright (c) 1999-2000 Andreas Kupries ([email protected])
*
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
* CVS: $Id: tclIOGT.c,v 1.20 2007/12/13 15:23:18 dgp Exp $
*/
#include "tclInt.h"
#include "tclIO.h"
/*
* Forward declarations of internal procedures. First the driver procedures of
* the transformation.
*/
static int TransformBlockModeProc(ClientData instanceData,
int mode);
static int TransformCloseProc(ClientData instanceData,
Tcl_Interp *interp);
static int TransformInputProc(ClientData instanceData, char *buf,
int toRead, int *errorCodePtr);
static int TransformOutputProc(ClientData instanceData,
const char *buf, int toWrite, int *errorCodePtr);
static int TransformSeekProc(ClientData instanceData, long offset,
int mode, int *errorCodePtr);
static int TransformSetOptionProc(ClientData instanceData,
Tcl_Interp *interp, const char *optionName,
const char *value);
static int TransformGetOptionProc(ClientData instanceData,
Tcl_Interp *interp, const char *optionName,
Tcl_DString *dsPtr);
static void TransformWatchProc(ClientData instanceData, int mask);
static int TransformGetFileHandleProc(ClientData instanceData,
int direction, ClientData *handlePtr);
static int TransformNotifyProc(ClientData instanceData, int mask);
static Tcl_WideInt TransformWideSeekProc(ClientData instanceData,
Tcl_WideInt offset, int mode, int *errorCodePtr);
/*
* Forward declarations of internal procedures. Secondly the procedures for
* handling and generating fileeevents.
*/
static void TransformChannelHandlerTimer(ClientData clientData);
/*
* Forward declarations of internal procedures. Third, helper procedures
* encapsulating essential tasks.
*/
typedef struct TransformChannelData TransformChannelData;
static int ExecuteCallback(TransformChannelData *ctrl,
Tcl_Interp *interp, unsigned char *op,
unsigned char *buf, int bufLen, int transmit,
int preserve);
/*
* Action codes to give to 'ExecuteCallback' (argument 'transmit'), telling
* the procedure what to do with the result of the script it calls.
*/
#define TRANSMIT_DONT 0 /* No transfer to do. */
#define TRANSMIT_DOWN 1 /* Transfer to the underlying channel. */
#define TRANSMIT_SELF 2 /* Transfer into our channel. */
#define TRANSMIT_IBUF 3 /* Transfer to internal input buffer. */
#define TRANSMIT_NUM 4 /* Transfer number to 'maxRead'. */
/*
* Codes for 'preserve' of 'ExecuteCallback'.
*/
#define P_PRESERVE 1
#define P_NO_PRESERVE 0
/*
* Strings for the action codes delivered to the script implementing a
* transformation. Argument 'op' of 'ExecuteCallback'.
*/
#define A_CREATE_WRITE (UCHARP("create/write"))
#define A_DELETE_WRITE (UCHARP("delete/write"))
#define A_FLUSH_WRITE (UCHARP("flush/write"))
#define A_WRITE (UCHARP("write"))
#define A_CREATE_READ (UCHARP("create/read"))
#define A_DELETE_READ (UCHARP("delete/read"))
#define A_FLUSH_READ (UCHARP("flush/read"))
#define A_READ (UCHARP("read"))
#define A_QUERY_MAXREAD (UCHARP("query/maxRead"))
#define A_CLEAR_READ (UCHARP("clear/read"))
/*
* Management of a simple buffer.
*/
typedef struct ResultBuffer ResultBuffer;
static inline void ResultClear(ResultBuffer *r);
static inline void ResultInit(ResultBuffer *r);
static inline int ResultEmpty(ResultBuffer *r);
static inline int ResultCopy(ResultBuffer *r, unsigned char *buf,
size_t toRead);
static inline void ResultAdd(ResultBuffer *r, unsigned char *buf,
size_t toWrite);
/*
* This structure describes the channel type structure for Tcl-based
* transformations.
*/
static Tcl_ChannelType transformChannelType = {
"transform", /* Type name. */
TCL_CHANNEL_VERSION_5, /* v5 channel */
TransformCloseProc, /* Close proc. */
TransformInputProc, /* Input proc. */
TransformOutputProc, /* Output proc. */
TransformSeekProc, /* Seek proc. */
TransformSetOptionProc, /* Set option proc. */
TransformGetOptionProc, /* Get option proc. */
TransformWatchProc, /* Initialize notifier. */
TransformGetFileHandleProc, /* Get OS handles out of channel. */
NULL, /* close2proc */
TransformBlockModeProc, /* Set blocking/nonblocking mode.*/
NULL, /* Flush proc. */
TransformNotifyProc, /* Handling of events bubbling up. */
TransformWideSeekProc, /* Wide seek proc. */
NULL, /* Thread action. */
NULL, /* Truncate. */
};
/*
* Possible values for 'flags' field in control structure, see below.
*/
#define CHANNEL_ASYNC (1<<0) /* Non-blocking mode. */
/*
* Definition of the structure containing the information about the internal
* input buffer.
*/
struct ResultBuffer {
unsigned char *buf; /* Reference to the buffer area. */
size_t allocated; /* Allocated size of the buffer area. */
size_t used; /* Number of bytes in the buffer, no more than
* number allocated. */
};
/*
* Additional bytes to allocate during buffer expansion.
*/
#define INCREMENT 512
/*
* Number of milliseconds to wait before firing an event to flush out
* information waiting in buffers (fileevent support).
*/
#define FLUSH_DELAY 5
/*
* Convenience macro to make some casts easier to use.
*/
#define UCHARP(x) ((unsigned char *) (x))
/*
* Definition of a structure used by all transformations generated here to
* maintain their local state.
*/
struct TransformChannelData {
/*
* General section. Data to integrate the transformation into the channel
* system.
*/
Tcl_Channel self; /* Our own Channel handle. */
int readIsFlushed; /* Flag to note whether in.flushProc was
* called or not. */
int flags; /* Currently CHANNEL_ASYNC or zero. */
int watchMask; /* Current watch/event/interest mask. */
int mode; /* Mode of parent channel, OR'ed combination
* of TCL_READABLE, TCL_WRITABLE. */
Tcl_TimerToken timer; /* Timer for automatic flushing of information
* sitting in an internal buffer. Required for
* full fileevent support. */
/*
* Transformation specific data.
*/
int maxRead; /* Maximum allowed number of bytes to read, as
* given to us by the Tcl script implementing
* the transformation. */
Tcl_Interp *interp; /* Reference to the interpreter which created
* the transformation. Used to execute the
* code below. */
Tcl_Obj *command; /* Tcl code to execute for a buffer */
ResultBuffer result; /* Internal buffer used to store the result of
* a transformation of incoming data. Also
* serves as buffer of all data not yet
* consumed by the reader. */
};
/*
*----------------------------------------------------------------------
*
* TclChannelTransform --
*
* Implements the Tcl "testchannel transform" debugging command. This is
* part of the testing environment. This sets up a tcl script (cmdObjPtr)
* to be used as a transform on the channel.
*
* Results:
* A standard Tcl result.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
/* ARGSUSED */
int
TclChannelTransform(
Tcl_Interp *interp, /* Interpreter for result. */
Tcl_Channel chan, /* Channel to transform. */
Tcl_Obj *cmdObjPtr) /* Script to use for transform. */
{
Channel *chanPtr; /* The actual channel. */
ChannelState *statePtr; /* State info for channel. */
int mode; /* Read/write mode of the channel. */
TransformChannelData *dataPtr;
Tcl_DString ds;
if (chan == NULL) {
return TCL_ERROR;
}
chanPtr = (Channel *) chan;
statePtr = chanPtr->state;
chanPtr = statePtr->topChanPtr;
chan = (Tcl_Channel) chanPtr;
mode = (statePtr->flags & (TCL_READABLE|TCL_WRITABLE));
/*
* Now initialize the transformation state and stack it upon the specified
* channel. One of the necessary things to do is to retrieve the blocking
* regime of the underlying channel and to use the same for us too.
*/
dataPtr = (TransformChannelData *) ckalloc(sizeof(TransformChannelData));
Tcl_DStringInit(&ds);
Tcl_GetChannelOption(interp, chan, "-blocking", &ds);
dataPtr->readIsFlushed = 0;
dataPtr->flags = 0;
if (ds.string[0] == '0') {
dataPtr->flags |= CHANNEL_ASYNC;
}
Tcl_DStringFree(&ds);
dataPtr->self = chan;
dataPtr->watchMask = 0;
dataPtr->mode = mode;
dataPtr->timer = NULL;
dataPtr->maxRead = 4096; /* Initial value not relevant. */
dataPtr->interp = interp;
dataPtr->command = cmdObjPtr;
Tcl_IncrRefCount(dataPtr->command);
ResultInit(&dataPtr->result);
dataPtr->self = Tcl_StackChannel(interp, &transformChannelType, dataPtr,
mode, chan);
if (dataPtr->self == NULL) {
Tcl_AppendResult(interp, "\nfailed to stack channel \"",
Tcl_GetChannelName(chan), "\"", NULL);
Tcl_DecrRefCount(dataPtr->command);
ResultClear(&dataPtr->result);
ckfree((char *) dataPtr);
return TCL_ERROR;
}
/*
* At last initialize the transformation at the script level.
*/
if ((dataPtr->mode & TCL_WRITABLE) && ExecuteCallback(dataPtr, NULL,
A_CREATE_WRITE, NULL, 0, TRANSMIT_DONT, P_NO_PRESERVE) != TCL_OK){
Tcl_UnstackChannel(interp, chan);
return TCL_ERROR;
}
if ((dataPtr->mode & TCL_READABLE) && ExecuteCallback(dataPtr, NULL,
A_CREATE_READ, NULL, 0, TRANSMIT_DONT, P_NO_PRESERVE) != TCL_OK) {
ExecuteCallback(dataPtr, NULL, A_DELETE_WRITE, NULL, 0, TRANSMIT_DONT,
P_NO_PRESERVE);
Tcl_UnstackChannel(interp, chan);
return TCL_ERROR;
}
return TCL_OK;
}
/*
*----------------------------------------------------------------------
*
* ExecuteCallback --
*
* Executes the defined callback for buffer and operation.
*
* Side effects:
* As of the executed tcl script.
*
* Result:
* A standard TCL error code. In case of an error a message is left in
* the result area of the specified interpreter.
*
*----------------------------------------------------------------------
*/
static int
ExecuteCallback(
TransformChannelData *dataPtr,
/* Transformation with the callback. */
Tcl_Interp *interp, /* Current interpreter, possibly NULL. */
unsigned char *op, /* Operation invoking the callback. */
unsigned char *buf, /* Buffer to give to the script. */
int bufLen, /* And its length. */
int transmit, /* Flag, determines whether the result of the
* callback is sent to the underlying channel
* or not. */
int preserve) /* Flag. If true the procedure will preserve
* the result state of all accessed
* interpreters. */
{
Tcl_Obj *resObj; /* See below, switch (transmit). */
int resLen;
unsigned char *resBuf;
Tcl_InterpState state = NULL;
int res = TCL_OK;
Tcl_Obj *command = Tcl_DuplicateObj(dataPtr->command);
/*
* Step 1, create the complete command to execute. Do this by appending
* operation and buffer to operate upon to a copy of the callback
* definition. We *cannot* create a list containing 3 objects and then use
* 'Tcl_EvalObjv', because the command may contain additional prefixed
* arguments. Feather's curried commands would come in handy here.
*/
if (preserve == P_PRESERVE) {
state = Tcl_SaveInterpState(dataPtr->interp, res);
}
Tcl_IncrRefCount(command);
res = Tcl_ListObjAppendElement(dataPtr->interp, command,
Tcl_NewStringObj((char *) op, -1));
if (res != TCL_OK) {
goto cleanup;
}
/*
* Use a byte-array to prevent the misinterpretation of binary data coming
* through as UTF while at the tcl level.
*/
res = Tcl_ListObjAppendElement(dataPtr->interp, command,
Tcl_NewByteArrayObj(buf, bufLen));
if (res != TCL_OK) {
goto cleanup;
}
/*
* Step 2, execute the command at the global level of the interpreter used
* to create the transformation. Destroy the command afterward. If an
* error occured and the current interpreter is defined and not equal to
* the interpreter for the callback, then copy the error message into
* current interpreter. Don't copy if in preservation mode.
*/
res = Tcl_EvalObjEx(dataPtr->interp, command, TCL_EVAL_GLOBAL);
Tcl_DecrRefCount(command);
command = NULL;
if ((res != TCL_OK) && (interp != NULL) && (dataPtr->interp != interp)
&& (preserve == P_NO_PRESERVE)) {
Tcl_SetObjResult(interp, Tcl_GetObjResult(dataPtr->interp));
return res;
}
/*
* Step 3, transmit a possible conversion result to the underlying
* channel, or ourselves.
*/
switch (transmit) {
case TRANSMIT_DONT:
/* nothing to do */
break;
case TRANSMIT_DOWN:
resObj = Tcl_GetObjResult(dataPtr->interp);
resBuf = Tcl_GetByteArrayFromObj(resObj, &resLen);
Tcl_WriteRaw(Tcl_GetStackedChannel(dataPtr->self), (char *) resBuf,
resLen);
break;
case TRANSMIT_SELF:
resObj = Tcl_GetObjResult(dataPtr->interp);
resBuf = Tcl_GetByteArrayFromObj(resObj, &resLen);
Tcl_WriteRaw(dataPtr->self, (char *) resBuf, resLen);
break;
case TRANSMIT_IBUF:
resObj = Tcl_GetObjResult(dataPtr->interp);
resBuf = Tcl_GetByteArrayFromObj(resObj, &resLen);
ResultAdd(&dataPtr->result, resBuf, resLen);
break;
case TRANSMIT_NUM:
/*
* Interpret result as integer number.
*/
resObj = Tcl_GetObjResult(dataPtr->interp);
TclGetIntFromObj(dataPtr->interp, resObj, &dataPtr->maxRead);
break;
}
Tcl_ResetResult(dataPtr->interp);
if (preserve == P_PRESERVE) {
(void) Tcl_RestoreInterpState(dataPtr->interp, state);
}
return res;
cleanup:
if (preserve == P_PRESERVE) {
(void) Tcl_RestoreInterpState(dataPtr->interp, state);
}
if (command != NULL) {
Tcl_DecrRefCount(command);
}
return res;
}
/*
*----------------------------------------------------------------------
*
* TransformBlockModeProc --
*
* Trap handler. Called by the generic IO system during option processing
* to change the blocking mode of the channel.
*
* Side effects:
* Forwards the request to the underlying channel.
*
* Result:
* 0 if successful, errno when failed.
*
*----------------------------------------------------------------------
*/
static int
TransformBlockModeProc(
ClientData instanceData, /* State of transformation. */
int mode) /* New blocking mode. */
{
TransformChannelData *dataPtr = instanceData;
if (mode == TCL_MODE_NONBLOCKING) {
dataPtr->flags |= CHANNEL_ASYNC;
} else {
dataPtr->flags &= ~CHANNEL_ASYNC;
}
return 0;
}
/*
*----------------------------------------------------------------------
*
* TransformCloseProc --
*
* Trap handler. Called by the generic IO system during destruction of
* the transformation channel.
*
* Side effects:
* Releases the memory allocated in 'Tcl_TransformObjCmd'.
*
* Result:
* None.
*
*----------------------------------------------------------------------
*/
static int
TransformCloseProc(
ClientData instanceData,
Tcl_Interp *interp)
{
TransformChannelData *dataPtr = instanceData;
/*
* Important: In this procedure 'dataPtr->self' already points to the
* underlying channel.
*
* There is no need to cancel an existing channel handler, this is already
* done. Either by 'Tcl_UnstackChannel' or by the general cleanup in
* 'Tcl_Close'.
*
* But we have to cancel an active timer to prevent it from firing on the
* removed channel.
*/
if (dataPtr->timer != NULL) {
Tcl_DeleteTimerHandler(dataPtr->timer);
dataPtr->timer = NULL;
}
/*
* Now flush data waiting in internal buffers to output and input. The
* input must be done despite the fact that there is no real receiver for
* it anymore. But the scripts might have sideeffects other parts of the
* system rely on (f.e. signaling the close to interested parties).
*/
if (dataPtr->mode & TCL_WRITABLE) {
ExecuteCallback(dataPtr, interp, A_FLUSH_WRITE, NULL, 0,
TRANSMIT_DOWN, P_PRESERVE);
}
if ((dataPtr->mode & TCL_READABLE) && !dataPtr->readIsFlushed) {
dataPtr->readIsFlushed = 1;
ExecuteCallback(dataPtr, interp, A_FLUSH_READ, NULL, 0, TRANSMIT_IBUF,
P_PRESERVE);
}
if (dataPtr->mode & TCL_WRITABLE) {
ExecuteCallback(dataPtr, interp, A_DELETE_WRITE, NULL, 0,
TRANSMIT_DONT, P_PRESERVE);
}
if (dataPtr->mode & TCL_READABLE) {
ExecuteCallback(dataPtr, interp, A_DELETE_READ, NULL, 0,
TRANSMIT_DONT, P_PRESERVE);
}
/*
* General cleanup.
*/
ResultClear(&dataPtr->result);
Tcl_DecrRefCount(dataPtr->command);
ckfree((char *) dataPtr);
return TCL_OK;
}
/*
*----------------------------------------------------------------------
*
* TransformInputProc --
*
* Called by the generic IO system to convert read data.
*
* Side effects:
* As defined by the conversion.
*
* Result:
* A transformed buffer.
*
*----------------------------------------------------------------------
*/
static int
TransformInputProc(
ClientData instanceData,
char *buf,
int toRead,
int *errorCodePtr)
{
TransformChannelData *dataPtr = instanceData;
int gotBytes, read, copied;
Tcl_Channel downChan;
/*
* Should assert(dataPtr->mode & TCL_READABLE);
*/
if (toRead == 0) {
/*
* Catch a no-op.
*/
return 0;
}
gotBytes = 0;
downChan = Tcl_GetStackedChannel(dataPtr->self);
while (toRead > 0) {
/*
* Loop until the request is satisfied (or no data is available from
* below, possibly EOF).
*/
copied = ResultCopy(&dataPtr->result, UCHARP(buf), toRead);
toRead -= copied;
buf += copied;
gotBytes += copied;
if (toRead == 0) {
/*
* The request was completely satisfied from our buffers. We can
* break out of the loop and return to the caller.
*/
return gotBytes;
}
/*
* Length (dataPtr->result) == 0, toRead > 0 here. Use the incoming
* 'buf'! as target to store the intermediary information read from
* the underlying channel.
*
* Ask the tcl level how much data it allows us to read from the
* underlying channel. This feature allows the transform to signal EOF
* upstream although there is none downstream. Useful to control an
* unbounded 'fcopy', either through counting bytes, or by pattern
* matching.
*/
ExecuteCallback(dataPtr, NULL, A_QUERY_MAXREAD, NULL, 0,
TRANSMIT_NUM /* -> maxRead */, P_PRESERVE);
if (dataPtr->maxRead >= 0) {
if (dataPtr->maxRead < toRead) {
toRead = dataPtr->maxRead;
}
} /* else: 'maxRead < 0' == Accept the current value of toRead. */
if (toRead <= 0) {
return gotBytes;
}
/*
* Get bytes from the underlying channel.
*/
read = Tcl_ReadRaw(downChan, buf, toRead);
if (read < 0) {
/*
* Report errors to caller. EAGAIN is a special situation. If we
* had some data before we report that instead of the request to
* re-try.
*/
if ((Tcl_GetErrno() == EAGAIN) && (gotBytes > 0)) {
return gotBytes;
}
*errorCodePtr = Tcl_GetErrno();
return -1;
} else if (read == 0) {
/*
* Check wether we hit on EOF in the underlying channel or not. If
* not differentiate between blocking and non-blocking modes. In
* non-blocking mode we ran temporarily out of data. Signal this
* to the caller via EWOULDBLOCK and error return (-1). In the
* other cases we simply return what we got and let the caller
* wait for more. On the other hand, if we got an EOF we have to
* convert and flush all waiting partial data.
*/
if (!Tcl_Eof(downChan)) {
if ((gotBytes == 0) && (dataPtr->flags & CHANNEL_ASYNC)) {
*errorCodePtr = EWOULDBLOCK;
return -1;
}
return gotBytes;
}
if (dataPtr->readIsFlushed) {
/*
* Already flushed, nothing to do anymore.
*/
return gotBytes;
}
dataPtr->readIsFlushed = 1;
ExecuteCallback(dataPtr, NULL, A_FLUSH_READ, NULL, 0,
TRANSMIT_IBUF, P_PRESERVE);
if (ResultEmpty(&dataPtr->result)) {
/*
* We had nothing to flush.
*/
return gotBytes;
}
continue; /* at: while (toRead > 0) */
} /* read == 0 */
/*
* Transform the read chunk and add the result to our read buffer
* (dataPtr->result).
*/
if (ExecuteCallback(dataPtr, NULL, A_READ, UCHARP(buf), read,
TRANSMIT_IBUF, P_PRESERVE) != TCL_OK) {
*errorCodePtr = EINVAL;
return -1;
}
} /* while toRead > 0 */
return gotBytes;
}
/*
*----------------------------------------------------------------------
*
* TransformOutputProc --
*
* Called by the generic IO system to convert data waiting to be written.
*
* Side effects:
* As defined by the transformation.
*
* Result:
* A transformed buffer.
*
*----------------------------------------------------------------------
*/
static int
TransformOutputProc(
ClientData instanceData,
const char *buf,
int toWrite,
int *errorCodePtr)
{
TransformChannelData *dataPtr = instanceData;
/*
* Should assert(dataPtr->mode & TCL_WRITABLE);
*/
if (toWrite == 0) {
/*
* Catch a no-op.
*/
return 0;
}
if (ExecuteCallback(dataPtr, NULL, A_WRITE, UCHARP(buf), toWrite,
TRANSMIT_DOWN, P_NO_PRESERVE) != TCL_OK) {
*errorCodePtr = EINVAL;
return -1;
}
return toWrite;
}
/*
*----------------------------------------------------------------------
*
* TransformSeekProc --
*
* This procedure is called by the generic IO level to move the access
* point in a channel.
*
* Side effects:
* Moves the location at which the channel will be accessed in future
* operations. Flushes all transformation buffers, then forwards it to
* the underlying channel.
*
* Result:
* -1 if failed, the new position if successful. An output argument
* contains the POSIX error code if an error occurred, or zero.
*
*----------------------------------------------------------------------
*/
static int
TransformSeekProc(
ClientData instanceData, /* The channel to manipulate. */
long offset, /* Size of movement. */
int mode, /* How to move. */
int *errorCodePtr) /* Location of error flag. */
{
TransformChannelData *dataPtr = instanceData;
Tcl_Channel parent = Tcl_GetStackedChannel(dataPtr->self);
Tcl_ChannelType *parentType = Tcl_GetChannelType(parent);
Tcl_DriverSeekProc *parentSeekProc = Tcl_ChannelSeekProc(parentType);
if ((offset == 0) && (mode == SEEK_CUR)) {
/*
* This is no seek but a request to tell the caller the current
* location. Simply pass the request down.
*/
return parentSeekProc(Tcl_GetChannelInstanceData(parent), offset,
mode, errorCodePtr);
}
/*
* It is a real request to change the position. Flush all data waiting for
* output and discard everything in the input buffers. Then pass the
* request down, unchanged.
*/
if (dataPtr->mode & TCL_WRITABLE) {
ExecuteCallback(dataPtr, NULL, A_FLUSH_WRITE, NULL, 0, TRANSMIT_DOWN,
P_NO_PRESERVE);
}
if (dataPtr->mode & TCL_READABLE) {
ExecuteCallback(dataPtr, NULL, A_CLEAR_READ, NULL, 0, TRANSMIT_DONT,
P_NO_PRESERVE);
ResultClear(&dataPtr->result);
dataPtr->readIsFlushed = 0;
}
return parentSeekProc(Tcl_GetChannelInstanceData(parent), offset, mode,
errorCodePtr);
}
/*
*----------------------------------------------------------------------
*
* TransformWideSeekProc --
*
* This procedure is called by the generic IO level to move the access
* point in a channel, with a (potentially) 64-bit offset.
*
* Side effects:
* Moves the location at which the channel will be accessed in future
* operations. Flushes all transformation buffers, then forwards it to
* the underlying channel.
*
* Result:
* -1 if failed, the new position if successful. An output argument
* contains the POSIX error code if an error occurred, or zero.
*
*----------------------------------------------------------------------
*/
static Tcl_WideInt
TransformWideSeekProc(
ClientData instanceData, /* The channel to manipulate. */
Tcl_WideInt offset, /* Size of movement. */
int mode, /* How to move. */
int *errorCodePtr) /* Location of error flag. */
{
TransformChannelData *dataPtr = instanceData;
Tcl_Channel parent = Tcl_GetStackedChannel(dataPtr->self);
Tcl_ChannelType *parentType = Tcl_GetChannelType(parent);
Tcl_DriverSeekProc *parentSeekProc = Tcl_ChannelSeekProc(parentType);
Tcl_DriverWideSeekProc *parentWideSeekProc =
Tcl_ChannelWideSeekProc(parentType);
ClientData parentData = Tcl_GetChannelInstanceData(parent);
if ((offset == Tcl_LongAsWide(0)) && (mode == SEEK_CUR)) {
/*
* This is no seek but a request to tell the caller the current
* location. Simply pass the request down.
*/
if (parentWideSeekProc != NULL) {
return parentWideSeekProc(parentData, offset, mode, errorCodePtr);
}
return Tcl_LongAsWide(parentSeekProc(parentData, 0, mode,
errorCodePtr));
}
/*
* It is a real request to change the position. Flush all data waiting for
* output and discard everything in the input buffers. Then pass the
* request down, unchanged.
*/
if (dataPtr->mode & TCL_WRITABLE) {
ExecuteCallback(dataPtr, NULL, A_FLUSH_WRITE, NULL, 0, TRANSMIT_DOWN,
P_NO_PRESERVE);
}
if (dataPtr->mode & TCL_READABLE) {
ExecuteCallback(dataPtr, NULL, A_CLEAR_READ, NULL, 0, TRANSMIT_DONT,
P_NO_PRESERVE);
ResultClear(&dataPtr->result);
dataPtr->readIsFlushed = 0;
}
/*
* If we have a wide seek capability, we should stick with that.
*/
if (parentWideSeekProc != NULL) {
return parentWideSeekProc(parentData, offset, mode, errorCodePtr);
}
/*
* We're transferring to narrow seeks at this point; this is a bit complex
* because we have to check whether the seek is possible first (i.e.
* whether we are losing information in truncating the bits of the
* offset). Luckily, there's a defined error for what happens when trying
* to go out of the representable range.
*/
if (offset<Tcl_LongAsWide(LONG_MIN) || offset>Tcl_LongAsWide(LONG_MAX)) {
*errorCodePtr = EOVERFLOW;
return Tcl_LongAsWide(-1);
}
return Tcl_LongAsWide(parentSeekProc(parentData, Tcl_WideAsLong(offset),
mode, errorCodePtr));
}
/*
*----------------------------------------------------------------------
*
* TransformSetOptionProc --
*
* Called by generic layer to handle the reconfiguration of channel
* specific options. As this channel type does not have such, it simply
* passes all requests downstream.
*
* Side effects:
* As defined by the channel downstream.
*
* Result:
* A standard TCL error code.
*
*----------------------------------------------------------------------
*/
static int
TransformSetOptionProc(
ClientData instanceData,
Tcl_Interp *interp,
const char *optionName,
const char *value)
{
TransformChannelData *dataPtr = instanceData;
Tcl_Channel downChan = Tcl_GetStackedChannel(dataPtr->self);
Tcl_DriverSetOptionProc *setOptionProc;
setOptionProc = Tcl_ChannelSetOptionProc(Tcl_GetChannelType(downChan));
if (setOptionProc == NULL) {
return TCL_ERROR;
}
return setOptionProc(Tcl_GetChannelInstanceData(downChan), interp,
optionName, value);
}
/*
*----------------------------------------------------------------------
*
* TransformGetOptionProc --
*
* Called by generic layer to handle requests for the values of channel
* specific options. As this channel type does not have such, it simply
* passes all requests downstream.
*
* Side effects:
* As defined by the channel downstream.
*
* Result:
* A standard TCL error code.
*
*----------------------------------------------------------------------
*/
static int
TransformGetOptionProc(
ClientData instanceData,
Tcl_Interp *interp,
const char *optionName,
Tcl_DString *dsPtr)
{
TransformChannelData *dataPtr = instanceData;
Tcl_Channel downChan = Tcl_GetStackedChannel(dataPtr->self);
Tcl_DriverGetOptionProc *getOptionProc;
getOptionProc = Tcl_ChannelGetOptionProc(Tcl_GetChannelType(downChan));
if (getOptionProc != NULL) {
return getOptionProc(Tcl_GetChannelInstanceData(downChan), interp,
optionName, dsPtr);
} else if (optionName == NULL) {
/*
* Request is query for all options, this is ok.
*/
return TCL_OK;
}
/*
* Request for a specific option has to fail, since we don't have any.
*/
return TCL_ERROR;
}
/*
*----------------------------------------------------------------------
*
* TransformWatchProc --
*
* Initialize the notifier to watch for events from this channel.
*
* Side effects:
* Sets up the notifier so that a future event on the channel will be
* seen by Tcl.
*
* Result:
* None.
*
*----------------------------------------------------------------------
*/
/* ARGSUSED */
static void
TransformWatchProc(
ClientData instanceData, /* Channel to watch. */
int mask) /* Events of interest. */
{
TransformChannelData *dataPtr = instanceData;
Tcl_Channel downChan;
/*
* The caller expressed interest in events occuring for this channel. We
* are forwarding the call to the underlying channel now.
*/
dataPtr->watchMask = mask;
/*
* No channel handlers any more. We will be notified automatically about
* events on the channel below via a call to our 'TransformNotifyProc'.
* But we have to pass the interest down now. We are allowed to add
* additional 'interest' to the mask if we want to. But this
* transformation has no such interest. It just passes the request down,
* unchanged.
*/
downChan = Tcl_GetStackedChannel(dataPtr->self);
Tcl_GetChannelType(downChan)->watchProc(
Tcl_GetChannelInstanceData(downChan), mask);
/*
* Management of the internal timer.
*/
if ((dataPtr->timer != NULL) &&
(!(mask & TCL_READABLE) || ResultEmpty(&dataPtr->result))) {
/*
* A pending timer exists, but either is there no (more) interest in
* the events it generates or nothing is available for reading, so
* remove it.
*/
Tcl_DeleteTimerHandler(dataPtr->timer);
dataPtr->timer = NULL;
}
if ((dataPtr->timer == NULL) && (mask & TCL_READABLE)
&& !ResultEmpty(&dataPtr->result)) {
/*
* There is no pending timer, but there is interest in readable events
* and we actually have data waiting, so generate a timer to flush
* that.
*/
dataPtr->timer = Tcl_CreateTimerHandler(FLUSH_DELAY,
TransformChannelHandlerTimer, dataPtr);
}
}
/*
*----------------------------------------------------------------------
*
* TransformGetFileHandleProc --
*
* Called from Tcl_GetChannelHandle to retrieve OS specific file handle
* from inside this channel.
*
* Side effects:
* None.
*
* Result:
* The appropriate Tcl_File or NULL if not present.
*
*----------------------------------------------------------------------
*/
static int
TransformGetFileHandleProc(
ClientData instanceData, /* Channel to query. */
int direction, /* Direction of interest. */
ClientData *handlePtr) /* Place to store the handle into. */
{
TransformChannelData *dataPtr = instanceData;
/*
* Return the handle belonging to parent channel. IOW, pass the request
* down and the result up.
*/
return Tcl_GetChannelHandle(Tcl_GetStackedChannel(dataPtr->self),
direction, handlePtr);
}
/*
*----------------------------------------------------------------------
*
* TransformNotifyProc --
*
* Handler called by Tcl to inform us of activity on the underlying
* channel.
*
* Side effects:
* May process the incoming event by itself.
*
* Result:
* None.
*
*----------------------------------------------------------------------
*/
static int
TransformNotifyProc(
ClientData clientData, /* The state of the notified
* transformation. */
int mask) /* The mask of occuring events. */
{
TransformChannelData *dataPtr = clientData;
/*
* An event occured in the underlying channel. This transformation doesn't
* process such events thus returns the incoming mask unchanged.
*/
if (dataPtr->timer != NULL) {
/*
* Delete an existing timer. It was not fired, yet we are here, so the
* channel below generated such an event and we don't have to. The
* renewal of the interest after the execution of channel handlers
* will eventually cause us to recreate the timer (in
* TransformWatchProc).
*/
Tcl_DeleteTimerHandler(dataPtr->timer);
dataPtr->timer = NULL;
}
return mask;
}
/*
*----------------------------------------------------------------------
*
* TransformChannelHandlerTimer --
*
* Called by the notifier (-> timer) to flush out information waiting in
* the input buffer.
*
* Side effects:
* As of 'Tcl_NotifyChannel'.
*
* Result:
* None.
*
*----------------------------------------------------------------------
*/
static void
TransformChannelHandlerTimer(
ClientData clientData) /* Transformation to query. */
{
TransformChannelData *dataPtr = clientData;
dataPtr->timer = NULL;
if (!(dataPtr->watchMask&TCL_READABLE) || ResultEmpty(&dataPtr->result)) {
/*
* The timer fired, but either is there no (more) interest in the
* events it generates or nothing is available for reading, so ignore
* it and don't recreate it.
*/
return;
}
Tcl_NotifyChannel(dataPtr->self, TCL_READABLE);
}
/*
*----------------------------------------------------------------------
*
* ResultClear --
*
* Deallocates any memory allocated by 'ResultAdd'.
*
* Side effects:
* See above.
*
* Result:
* None.
*
*----------------------------------------------------------------------
*/
static inline void
ResultClear(
ResultBuffer *r) /* Reference to the buffer to clear out. */
{
r->used = 0;
if (r->allocated) {
ckfree((char *) r->buf);
r->buf = NULL;
r->allocated = 0;
}
}
/*
*----------------------------------------------------------------------
*
* ResultInit --
*
* Initializes the specified buffer structure. The structure will contain
* valid information for an emtpy buffer.
*
* Side effects:
* See above.
*
* Result:
* None.
*
*----------------------------------------------------------------------
*/
static inline void
ResultInit(
ResultBuffer *r) /* Reference to the structure to
* initialize. */
{
r->used = 0;
r->allocated = 0;
r->buf = NULL;
}
/*
*----------------------------------------------------------------------
*
* ResultEmpty --
*
* Returns whether the number of bytes stored in the buffer is zero.
*
* Side effects:
* None.
*
* Result:
* A boolean.
*
*----------------------------------------------------------------------
*/
static inline int
ResultEmpty(
ResultBuffer *r) /* The structure to query. */
{
return r->used == 0;
}
/*
*----------------------------------------------------------------------
*
* ResultCopy --
*
* Copies the requested number of bytes from the buffer into the
* specified array and removes them from the buffer afterward. Copies
* less if there is not enough data in the buffer.
*
* Side effects:
* See above.
*
* Result:
* The number of actually copied bytes, possibly less than 'toRead'.
*
*----------------------------------------------------------------------
*/
static inline int
ResultCopy(
ResultBuffer *r, /* The buffer to read from. */
unsigned char *buf, /* The buffer to copy into. */
size_t toRead) /* Number of requested bytes. */
{
if (r->used == 0) {
/*
* Nothing to copy in the case of an empty buffer.
*/
return 0;
} else if (r->used == toRead) {
/*
* We have just enough. Copy everything to the caller.
*/
memcpy(buf, r->buf, toRead);
r->used = 0;
} else if (r->used > toRead) {
/*
* The internal buffer contains more than requested. Copy the
* requested subset to the caller, and shift the remaining bytes down.
*/
memcpy(buf, r->buf, toRead);
memmove(r->buf, r->buf + toRead, r->used - toRead);
r->used -= toRead;
} else {
/*
* There is not enough in the buffer to satisfy the caller, so take
* everything.
*/
memcpy(buf, r->buf, r->used);
toRead = r->used;
r->used = 0;
}
return toRead;
}
/*
*----------------------------------------------------------------------
*
* ResultAdd --
*
* Adds the bytes in the specified array to the buffer, by appending it.
*
* Side effects:
* See above.
*
* Result:
* None.
*
*----------------------------------------------------------------------
*/
static inline void
ResultAdd(
ResultBuffer *r, /* The buffer to extend. */
unsigned char *buf, /* The buffer to read from. */
size_t toWrite) /* The number of bytes in 'buf'. */
{
if (r->used + toWrite > r->allocated) {
/*
* Extension of the internal buffer is required.
*/
if (r->allocated == 0) {
r->allocated = toWrite + INCREMENT;
r->buf = UCHARP(ckalloc(r->allocated));
} else {
r->allocated += toWrite + INCREMENT;
r->buf = UCHARP(ckrealloc((char *) r->buf, r->allocated));
}
}
/*
* Now we may copy the data.
*/
memcpy(r->buf + r->used, buf, toWrite);
r->used += toWrite;
}
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/
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