572 lines
23 KiB
Groff
572 lines
23 KiB
Groff
'\"
|
|
'\" Copyright (c) 1996-1997 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: @(#) CrtChannel.3 1.29 97/06/20 13:37:45
|
|
.so man.macros
|
|
.TH Tcl_CreateChannel 3 8.0 Tcl "Tcl Library Procedures"
|
|
.BS
|
|
'\" Note: do not modify the .SH NAME line immediately below!
|
|
.SH NAME
|
|
Tcl_CreateChannel, Tcl_GetChannelInstanceData, Tcl_GetChannelType, Tcl_GetChannelName, Tcl_GetChannelHandle, Tcl_GetChannelMode, Tcl_GetChannelBufferSize, Tcl_SetDefaultTranslation, Tcl_SetChannelBufferSize, Tcl_NotifyChannel, Tcl_BadChannelOption \- procedures for creating and manipulating channels
|
|
.SH SYNOPSIS
|
|
.nf
|
|
\fB#include <tcl.h>\fR
|
|
.sp
|
|
Tcl_Channel
|
|
\fBTcl_CreateChannel\fR(\fItypePtr, channelName, instanceData, mask\fR)
|
|
.sp
|
|
ClientData
|
|
\fBTcl_GetChannelInstanceData\fR(\fIchannel\fR)
|
|
.sp
|
|
Tcl_ChannelType *
|
|
\fBTcl_GetChannelType\fR(\fIchannel\fR)
|
|
.sp
|
|
char *
|
|
\fBTcl_GetChannelName\fR(\fIchannel\fR)
|
|
.VS
|
|
.sp
|
|
int
|
|
\fBTcl_GetChannelHandle\fR(\fIchannel, direction, handlePtr\fR)
|
|
.VE
|
|
.sp
|
|
int
|
|
\fBTcl_GetChannelFlags\fR(\fIchannel\fR)
|
|
.sp
|
|
\fBTcl_SetDefaultTranslation\fR(\fIchannel, transMode\fR)
|
|
.sp
|
|
int
|
|
\fBTcl_GetChannelBufferSize\fR(\fIchannel\fR)
|
|
.sp
|
|
\fBTcl_SetChannelBufferSize\fR(\fIchannel, size\fR)
|
|
.sp
|
|
.VS
|
|
\fBTcl_NotifyChannel\fR(\fIchannel, mask\fR)
|
|
.sp
|
|
int
|
|
\fBTcl_BadChannelOption\fR(\fIinterp, optionName, optionList\fR)
|
|
.VE
|
|
.sp
|
|
.SH ARGUMENTS
|
|
.AS Tcl_EolTranslation *channelName in
|
|
.AP Tcl_ChannelType *typePtr in
|
|
Points to a structure containing the addresses of procedures that
|
|
can be called to perform I/O and other functions on the channel.
|
|
.AP char *channelName in
|
|
The name of this channel, such as \fBfile3\fR; must not be in use
|
|
by any other channel. Can be NULL, in which case the channel is
|
|
created without a name.
|
|
.AP ClientData instanceData in
|
|
Arbitrary one-word value to be associated with this channel. This
|
|
value is passed to procedures in \fItypePtr\fR when they are invoked.
|
|
.AP int mask in
|
|
OR-ed combination of \fBTCL_READABLE\fR and \fBTCL_WRITABLE\fR to indicate
|
|
whether a channel is readable and writable.
|
|
.AP Tcl_Channel channel in
|
|
The channel to operate on.
|
|
.VS
|
|
.AP int direction in
|
|
\fBTCL_READABLE\fR means the input handle is wanted; \fBTCL_WRITABLE\fR
|
|
means the output handle is wanted.
|
|
.AP ClientData *handlePtr out
|
|
Points to the location where the desired OS-specific handle should be
|
|
stored.
|
|
.VE
|
|
.AP Tcl_EolTranslation transMode in
|
|
The translation mode; one of the constants \fBTCL_TRANSLATE_AUTO\fR,
|
|
\fBTCL_TRANSLATE_CR\fR, \fBTCL_TRANSLATE_LF\fR and \fBTCL_TRANSLATE_CRLF\fR.
|
|
.AP int size in
|
|
The size, in bytes, of buffers to allocate in this channel.
|
|
.VS
|
|
.AP int mask in
|
|
An OR-ed combination of \fBTCL_READABLE\fR, \fBTCL_WRITABLE\fR
|
|
and \fBTCL_EXCEPTION\fR that indicates events that have occurred on
|
|
this channel.
|
|
.AP Tcl_Interp *interp in
|
|
Current interpreter. (can be NULL)
|
|
.AP char *optionName in
|
|
Name of the invalid option.
|
|
.AP char *optionList in
|
|
Specific options list (space separated words, without "-")
|
|
to append to the standard generic options list.
|
|
Can be NULL for generic options error message only.
|
|
.VE
|
|
|
|
.BE
|
|
|
|
.SH DESCRIPTION
|
|
.PP
|
|
Tcl uses a two-layered channel architecture. It provides a generic upper
|
|
layer to enable C and Tcl programs to perform input and output using the
|
|
same APIs for a variety of files, devices, sockets etc. The generic C APIs
|
|
are described in the manual entry for \fBTcl_OpenFileChannel\fR.
|
|
.PP
|
|
The lower layer provides type-specific channel drivers for each type
|
|
of device supported on each platform. This manual entry describes the
|
|
C APIs used to communicate between the generic layer and the
|
|
type-specific channel drivers. It also explains how new types of
|
|
channels can be added by providing new channel drivers.
|
|
.PP
|
|
Channel drivers consist of a number of components: First, each channel
|
|
driver provides a \fBTcl_ChannelType\fR structure containing pointers to
|
|
functions implementing the various operations used by the generic layer to
|
|
communicate with the channel driver. The \fBTcl_ChannelType\fR structure
|
|
and the functions referenced by it are described in the section
|
|
TCL_CHANNELTYPE, below.
|
|
.PP
|
|
Second, channel drivers usually provide a Tcl command to create
|
|
instances of that type of channel. For example, the Tcl \fBopen\fR
|
|
command creates channels that use the file and command channel
|
|
drivers, and the Tcl \fBsocket\fR command creates channels that use
|
|
TCP sockets for network communication.
|
|
.PP
|
|
Third, a channel driver optionally provides a C function to open
|
|
channel instances of that type. For example, \fBTcl_OpenFileChannel\fR
|
|
opens a channel that uses the file channel driver, and
|
|
\fBTcl_OpenTcpClient\fR opens a channel that uses the TCP network
|
|
protocol. These creation functions typically use
|
|
\fBTcl_CreateChannel\fR internally to open the channel.
|
|
.PP
|
|
To add a new type of channel you must implement a C API or a Tcl command
|
|
that opens a channel by invoking \fBTcl_CreateChannel\fR.
|
|
When your driver calls \fBTcl_CreateChannel\fR it passes in
|
|
a \fBTcl_ChannelType\fR structure describing the driver's I/O
|
|
procedures.
|
|
The generic layer will then invoke the functions referenced in that
|
|
structure to perform operations on the channel.
|
|
.PP
|
|
\fBTcl_CreateChannel\fR opens a new channel and associates the supplied
|
|
\fItypePtr\fR and \fIinstanceData\fR with it. The channel is opened in the
|
|
mode indicated by \fImask\fR.
|
|
For a discussion of channel drivers, their operations and the
|
|
\fBTcl_ChannelType\fR structure, see the section TCL_CHANNELTYPE, below.
|
|
.PP
|
|
\fBTcl_GetChannelInstanceData\fR returns the instance data associated with
|
|
the channel in \fIchannel\fR. This is the same as the \fIinstanceData\fR
|
|
argument in the call to \fBTcl_CreateChannel\fR that created this channel.
|
|
.PP
|
|
\fBTcl_GetChannelType\fR returns a pointer to the \fBTcl_ChannelType\fR
|
|
structure used by the channel in the \fIchannel\fR argument. This is
|
|
the same as the \fItypePtr\fR argument in the call to
|
|
\fBTcl_CreateChannel\fR that created this channel.
|
|
.PP
|
|
\fBTcl_GetChannelName\fR returns a string containing the name associated
|
|
with the channel, or NULL if the \fIchannelName\fR argument to
|
|
\fBTcl_CreateChannel\fR was NULL.
|
|
.PP
|
|
.VS
|
|
\fBTcl_GetChannelHandle\fR places the OS-specific device handle
|
|
associated with \fIchannel\fR for the given \fIdirection\fR in the
|
|
location specified by \fIhandlePtr\fR and returns \fBTCL_OK\fR. If
|
|
the channel does not have a device handle for the specified direction,
|
|
then \fBTCL_ERROR\fR is returned instead. Different channel drivers
|
|
will return different types of handle. Refer to the manual entries
|
|
for each driver to determine what type of handle is returned.
|
|
.VE
|
|
.PP
|
|
\fBTcl_GetChannelMode\fR returns an OR-ed combination of \fBTCL_READABLE\fR
|
|
and \fBTCL_WRITABLE\fR, indicating whether the channel is open for input
|
|
and output.
|
|
.PP
|
|
\fBTcl_SetDefaultTranslation\fR sets the default end of line translation
|
|
mode. This mode will be installed as the translation mode for the channel
|
|
if an attempt is made to output on the channel while it is still in
|
|
\fBTCL_TRANSLATE_AUTO\fR mode. For a description of end of line translation
|
|
modes, see the manual entry for \fBfconfigure\fR.
|
|
.PP
|
|
\fBTcl_GetChannelBufferSize\fR returns the size, in bytes, of buffers
|
|
allocated to store input or output in \fIchan\fR. If the value was not set
|
|
by a previous call to \fBTcl_SetChannelBufferSize\fR, described below, then
|
|
the default value of 4096 is returned.
|
|
.PP
|
|
\fBTcl_SetChannelBufferSize\fR sets the size, in bytes, of buffers that
|
|
will be allocated in subsequent operations on the channel to store input or
|
|
output. The \fIsize\fR argument should be between ten and one million,
|
|
allowing buffers of ten bytes to one million bytes. If \fIsize\fR is
|
|
outside this range, \fBTcl_SetChannelBufferSize\fR sets the buffer size to
|
|
4096.
|
|
.PP
|
|
.VS
|
|
\fBTcl_NotifyChannel\fR is called by a channel driver to indicate to
|
|
the generic layer that the events specified by \fImask\fR have
|
|
occurred on the channel. Channel drivers are responsible for invoking
|
|
this function whenever the channel handlers need to be called for the
|
|
channel. See \fBWATCHPROC\fR below for more details.
|
|
.VE
|
|
.PP
|
|
.VS
|
|
\fBTcl_BadChannelOption\fR is called from driver specific set or get option
|
|
procs to generate a complete error message.
|
|
.VE
|
|
|
|
.SH TCL_CHANNELTYPE
|
|
.PP
|
|
A channel driver provides a \fBTcl_ChannelType\fR structure that contains
|
|
pointers to functions that implement the various operations on a channel;
|
|
these operations are invoked as needed by the generic layer. The
|
|
\fBTcl_ChannelType\fR structure contains the following fields:
|
|
.PP
|
|
.VS
|
|
.CS
|
|
typedef struct Tcl_ChannelType {
|
|
char *\fItypeName\fR;
|
|
Tcl_DriverBlockModeProc *\fIblockModeProc\fR;
|
|
Tcl_DriverCloseProc *\fIcloseProc\fR;
|
|
Tcl_DriverInputProc *\fIinputProc\fR;
|
|
Tcl_DriverOutputProc *\fIoutputProc\fR;
|
|
Tcl_DriverSeekProc *\fIseekProc\fR;
|
|
Tcl_DriverSetOptionProc *\fIsetOptionProc\fR;
|
|
Tcl_DriverGetOptionProc *\fIgetOptionProc\fR;
|
|
Tcl_DriverWatchProc *\fIwatchProc\fR;
|
|
Tcl_DriverGetHandleProc *\fIgetHandleProc\fR;
|
|
} Tcl_ChannelType;
|
|
.CE
|
|
.VE
|
|
.PP
|
|
The driver must provide implementations for all functions except
|
|
\fIblockModeProc\fR, \fIseekProc\fR, \fIsetOptionProc\fR, and
|
|
\fIgetOptionProc\fR, which may be specified as NULL to indicate that the
|
|
channel does not support seeking. Other functions that can not be
|
|
implemented for this type of device should return \fBEINVAL\fR when invoked
|
|
to indicate that they are not implemented.
|
|
|
|
.SH TYPENAME
|
|
.PP
|
|
The \fItypeName\fR field contains a null-terminated string that
|
|
identifies the type of the device implemented by this driver, e.g.
|
|
\fBfile\fR or \fBsocket\fR.
|
|
|
|
.SH BLOCKMODEPROC
|
|
.PP
|
|
The \fIblockModeProc\fR field contains the address of a function called by
|
|
the generic layer to set blocking and nonblocking mode on the device.
|
|
\fIBlockModeProc\fR should match the following prototype:
|
|
.PP
|
|
.CS
|
|
typedef int Tcl_DriverBlockModeProc(
|
|
ClientData \fIinstanceData\fR,
|
|
int \fImode\fR);
|
|
.CE
|
|
.PP
|
|
The \fIinstanceData\fR is the same as the value passed to
|
|
\fBTcl_CreateChannel\fR when this channel was created. The \fImode\fR
|
|
argument is either \fBTCL_MODE_BLOCKING\fR or \fBTCL_MODE_NONBLOCKING\fR to
|
|
set the device into blocking or nonblocking mode. The function should
|
|
return zero if the operation was successful, or a nonzero POSIX error code
|
|
if the operation failed.
|
|
.PP
|
|
If the operation is successful, the function can modify the supplied
|
|
\fIinstanceData\fR to record that the channel entered blocking or
|
|
nonblocking mode and to implement the blocking or nonblocking behavior.
|
|
For some device types, the blocking and nonblocking behavior can be
|
|
implemented by the underlying operating system; for other device types, the
|
|
behavior must be emulated in the channel driver.
|
|
|
|
.SH CLOSEPROC
|
|
.PP
|
|
The \fIcloseProc\fR field contains the address of a function called by the
|
|
generic layer to clean up driver-related information when the channel is
|
|
closed. \fICloseProc\fR must match the following prototype:
|
|
.PP
|
|
.CS
|
|
typedef int Tcl_DriverCloseProc(
|
|
ClientData \fIinstanceData\fR,
|
|
Tcl_Interp *\fIinterp\fR);
|
|
.CE
|
|
.PP
|
|
The \fIinstanceData\fR argument is the same as the value provided to
|
|
\fBTcl_CreateChannel\fR when the channel was created. The function should
|
|
release any storage maintained by the channel driver for this channel, and
|
|
close the input and output devices encapsulated by this channel. All queued
|
|
output will have been flushed to the device before this function is called,
|
|
and no further driver operations will be invoked on this instance after
|
|
calling the \fIcloseProc\fR. If the close operation is successful, the
|
|
procedure should return zero; otherwise it should return a nonzero POSIX
|
|
error code. In addition, if an error occurs and \fIinterp\fR is not NULL,
|
|
the procedure should store an error message in \fIinterp->result\fR.
|
|
|
|
.SH INPUTPROC
|
|
.PP
|
|
The \fIinputProc\fR field contains the address of a function called by the
|
|
generic layer to read data from the file or device and store it in an
|
|
internal buffer. \fIInputProc\fR must match the following prototype:
|
|
.PP
|
|
.CS
|
|
typedef int Tcl_DriverInputProc(
|
|
ClientData \fIinstanceData\fR,
|
|
char *\fIbuf\fR,
|
|
int \fIbufSize\fR,
|
|
int *\fIerrorCodePtr\fR);
|
|
.CE
|
|
.PP
|
|
\fIInstanceData\fR is the same as the value passed to
|
|
\fBTcl_CreateChannel\fR when the channel was created. The \fIbuf\fR
|
|
argument points to an array of bytes in which to store input from the
|
|
device, and the \fIbufSize\fR argument indicates how many bytes are
|
|
available at \fIbuf\fR.
|
|
.PP
|
|
The \fIerrorCodePtr\fR argument points to an integer variable provided by
|
|
the generic layer. If an error occurs, the function should set the variable
|
|
to a POSIX error code that identifies the error that occurred.
|
|
.PP
|
|
The function should read data from the input device encapsulated by the
|
|
channel and store it at \fIbuf\fR. On success, the function should return
|
|
a nonnegative integer indicating how many bytes were read from the input
|
|
device and stored at \fIbuf\fR. On error, the function should return -1. If
|
|
an error occurs after some data has been read from the device, that data is
|
|
lost.
|
|
.PP
|
|
If \fIinputProc\fR can determine that the input device has some data
|
|
available but less than requested by the \fIbufSize\fR argument, the
|
|
function should only attempt to read as much data as is available and
|
|
return without blocking. If the input device has no data available
|
|
whatsoever and the channel is in nonblocking mode, the function should
|
|
return an \fBEAGAIN\fR error. If the input device has no data available
|
|
whatsoever and the channel is in blocking mode, the function should block
|
|
for the shortest possible time until at least one byte of data can be read
|
|
from the device; then, it should return as much data as it can read without
|
|
blocking.
|
|
|
|
.SH OUTPUTPROC
|
|
.PP
|
|
The \fIoutputProc\fR field contains the address of a function called by the
|
|
generic layer to transfer data from an internal buffer to the output device.
|
|
\fIOutputProc\fR must match the following prototype:
|
|
.PP
|
|
.CS
|
|
typedef int Tcl_DriverOutputProc(
|
|
ClientData \fIinstanceData\fR,
|
|
char *\fIbuf\fR,
|
|
int \fItoWrite\fR,
|
|
int *\fIerrorCodePtr\fR);
|
|
.CE
|
|
.PP
|
|
\fIInstanceData\fR is the same as the value passed to
|
|
\fBTcl_CreateChannel\fR when the channel was created. The \fIbuf\fR
|
|
argument contains an array of bytes to be written to the device, and the
|
|
\fItoWrite\fR argument indicates how many bytes are to be written from the
|
|
\fIbuf\fR argument.
|
|
.PP
|
|
The \fIerrorCodePtr\fR argument points to an integer variable provided by
|
|
the generic layer. If an error occurs, the function should set this
|
|
variable to a POSIX error code that identifies the error.
|
|
.PP
|
|
The function should write the data at \fIbuf\fR to the output device
|
|
encapsulated by the channel. On success, the function should return a
|
|
nonnegative integer indicating how many bytes were written to the output
|
|
device. The return value is normally the same as \fItoWrite\fR, but may be
|
|
less in some cases such as if the output operation is interrupted by a
|
|
signal. If an error occurs the function should return -1. In case of
|
|
error, some data may have been written to the device.
|
|
.PP
|
|
If the channel is nonblocking and the output device is unable to absorb any
|
|
data whatsoever, the function should return -1 with an \fBEAGAIN\fR error
|
|
without writing any data.
|
|
|
|
.SH SEEKPROC
|
|
.PP
|
|
The \fIseekProc\fR field contains the address of a function called by the
|
|
generic layer to move the access point at which subsequent input or output
|
|
operations will be applied. \fISeekProc\fR must match the following
|
|
prototype:
|
|
.PP
|
|
.CS
|
|
typedef int Tcl_DriverSeekProc(
|
|
ClientData \fIinstanceData\fR,
|
|
long \fIoffset\fR,
|
|
int \fIseekMode\fR,
|
|
int *\fIerrorCodePtr\fR);
|
|
.CE
|
|
.PP
|
|
The \fIinstanceData\fR argument is the same as the value given to
|
|
\fBTcl_CreateChannel\fR when this channel was created. \fIOffset\fR and
|
|
\fIseekMode\fR have the same meaning as for the \fBTcl_SeekChannel\fR
|
|
procedure (described in the manual entry for \fBTcl_OpenFileChannel\fR).
|
|
.PP
|
|
The \fIerrorCodePtr\fR argument points to an integer variable provided by
|
|
the generic layer for returning \fBerrno\fR values from the function. The
|
|
function should set this variable to a POSIX error code if an error occurs.
|
|
The function should store an \fBEINVAL\fR error code if the channel type
|
|
does not implement seeking.
|
|
.PP
|
|
The return value is the new access point or -1 in case of error. If an
|
|
error occurred, the function should not move the access point.
|
|
|
|
.SH SETOPTIONPROC
|
|
.PP
|
|
The \fIsetOptionProc\fR field contains the address of a function called by
|
|
the generic layer to set a channel type specific option on a channel.
|
|
\fIsetOptionProc\fR must match the following prototype:
|
|
.PP
|
|
.CS
|
|
typedef int Tcl_DriverSetOptionProc(
|
|
ClientData \fIinstanceData\fR,
|
|
Tcl_Interp *\fIinterp\fR,
|
|
char *\fIoptionName\fR,
|
|
char *\fIoptionValue\fR);
|
|
.CE
|
|
.PP
|
|
\fIoptionName\fR is the name of an option to set, and \fIoptionValue\fR is
|
|
the new value for that option, as a string. The \fIinstanceData\fR is the
|
|
same as the value given to \fBTcl_CreateChannel\fR when this channel was
|
|
created. The function should do whatever channel type specific action is
|
|
required to implement the new value of the option.
|
|
.PP
|
|
Some options are handled by the generic code and this function is never
|
|
called to set them, e.g. \fB-blockmode\fR. Other options are specific to
|
|
each channel type and the \fIsetOptionProc\fR procedure of the channel
|
|
driver will get called to implement them. The \fIsetOptionProc\fR field can
|
|
be NULL, which indicates that this channel type supports no type specific
|
|
options.
|
|
.PP
|
|
If the option value is successfully modified to the new value, the function
|
|
returns \fBTCL_OK\fR.
|
|
.VS
|
|
It should call \fBTcl_BadChannelOption\fR which itself returns
|
|
\fBTCL_ERROR\fR if the \fIoptionName\fR is
|
|
unrecognized.
|
|
.VE
|
|
If \fIoptionValue\fR specifies a value for the option that
|
|
is not supported or if a system call error occurs,
|
|
the function should leave an error message in the
|
|
\fIresult\fR field of \fIinterp\fR if \fIinterp\fR is not NULL. The
|
|
function should also call \fBTcl_SetErrno\fR to store an appropriate POSIX
|
|
error code.
|
|
|
|
.SH GETOPTIONPROC
|
|
.PP
|
|
The \fIgetOptionProc\fR field contains the address of a function called by
|
|
the generic layer to get the value of a channel type specific option on a
|
|
channel. \fIgetOptionProc\fR must match the following prototype:
|
|
.PP
|
|
.CS
|
|
typedef int Tcl_DriverGetOptionProc(
|
|
ClientData \fIinstanceData\fR,
|
|
.VS
|
|
Tcl_Interp *\fIinterp\fR,
|
|
.VE
|
|
char *\fIoptionName\fR,
|
|
Tcl_DString *\fIdsPtr\fR);
|
|
.CE
|
|
.PP
|
|
\fIOptionName\fR is the name of an option supported by this type of
|
|
channel. If the option name is not NULL, the function stores its current
|
|
value, as a string, in the Tcl dynamic string \fIdsPtr\fR.
|
|
If \fIoptionName\fR is NULL, the function stores in \fIdsPtr\fR an
|
|
alternating list of all supported options and their current values.
|
|
On success, the function returns \fBTCL_OK\fR.
|
|
.VS
|
|
It should call \fBTcl_BadChannelOption\fR which itself returns
|
|
\fBTCL_ERROR\fR if the \fIoptionName\fR is
|
|
unrecognized. If a system call error occurs,
|
|
the function should leave an error message in the
|
|
\fIresult\fR field of \fIinterp\fR if \fIinterp\fR is not NULL. The
|
|
function should also call \fBTcl_SetErrno\fR to store an appropriate POSIX
|
|
error code.
|
|
.VE
|
|
.PP
|
|
Some options are handled by the generic code and this function is never
|
|
called to retrieve their value, e.g. \fB-blockmode\fR. Other options are
|
|
specific to each channel type and the \fIgetOptionProc\fR procedure of the
|
|
channel driver will get called to implement them. The \fIgetOptionProc\fR
|
|
field can be NULL, which indicates that this channel type supports no type
|
|
specific options.
|
|
|
|
.SH WATCHPROC
|
|
.VS
|
|
.PP
|
|
The \fIwatchProc\fR field contains the address of a function called
|
|
by the generic layer to initialize the event notification mechanism to
|
|
notice events of interest on this channel.
|
|
\fIWatchProc\fR should match the following prototype:
|
|
.PP
|
|
.CS
|
|
typedef void Tcl_DriverWatchProc(
|
|
ClientData \fIinstanceData\fR,
|
|
int \fImask\fR);
|
|
.CE
|
|
.VE
|
|
.PP
|
|
The \fIinstanceData\fR is the same as the value passed to
|
|
\fBTcl_CreateChannel\fR when this channel was created. The \fImask\fR
|
|
argument is an OR-ed combination of \fBTCL_READABLE\fR, \fBTCL_WRITABLE\fR
|
|
and \fBTCL_EXCEPTION\fR; it indicates events the caller is interested in
|
|
noticing on this channel.
|
|
.PP
|
|
.VS
|
|
The function should initialize device type specific mechanisms to
|
|
notice when an event of interest is present on the channel. When one
|
|
or more of the designated events occurs on the channel, the channel
|
|
driver is responsible for calling \fBTcl_NotifyChannel\fR to inform
|
|
the generic channel module. The driver should take care not to starve
|
|
other channel drivers or sources of callbacks by invoking
|
|
Tcl_NotifyChannel too frequently. Fairness can be insured by using
|
|
the Tcl event queue to allow the channel event to be scheduled in sequence
|
|
with other events. See the description of \fBTcl_QueueEvent\fR for
|
|
details on how to queue an event.
|
|
|
|
.SH GETHANDLEPROC
|
|
.PP
|
|
The \fIgetHandleProc\fR field contains the address of a function called by
|
|
the generic layer to retrieve a device-specific handle from the channel.
|
|
\fIGetHandleProc\fR should match the following prototype:
|
|
.PP
|
|
.CS
|
|
typedef int Tcl_DriverGetHandleProc(
|
|
ClientData \fIinstanceData\fR,
|
|
int \fIdirection\fR,
|
|
ClientData *\fIhandlePtr\fR);
|
|
.CE
|
|
.PP
|
|
\fIInstanceData is the same as the value passed to
|
|
\fBTcl_CreateChannel\fR when this channel was created. The \fIdirection\fR
|
|
argument is either \fBTCL_READABLE\fR to retrieve the handle used
|
|
for input, or \fBTCL_WRITABLE\fR to retrieve the handle used for
|
|
output.
|
|
.PP
|
|
If the channel implementation has device-specific handles, the
|
|
function should retrieve the appropriate handle associated with the
|
|
channel, according the \fIdirection\fR argument. The handle should be
|
|
stored in the location referred to by \fIhandlePtr\fR, and
|
|
\fBTCL_OK\fR should be returned. If the channel is not open for the
|
|
specified direction, or if the channel implementation does not use
|
|
device handles, the function should return \fBTCL_ERROR\fR.
|
|
.VE
|
|
|
|
.VS
|
|
.SH TCL_BADCHANNELOPTION
|
|
.PP
|
|
This procedure generates a "bad option" error message in an
|
|
(optional) interpreter. It is used by channel drivers when
|
|
a invalid Set/Get option is requested. Its purpose is to concatenate
|
|
the generic options list to the specific ones and factorize
|
|
the generic options error message string.
|
|
.PP
|
|
It always return \fBTCL_ERROR\fR
|
|
.PP
|
|
An error message is generated in interp's result object to
|
|
indicate that a command was invoked with the a bad option
|
|
The message has the form
|
|
.CS
|
|
bad option "blah": should be one of
|
|
<...generic options...>+<...specific options...>
|
|
so you get for instance:
|
|
bad option "-blah": should be one of -blocking,
|
|
-buffering, -buffersize, -eofchar, -translation,
|
|
-peername, or -sockname
|
|
when called with optionList="peername sockname"
|
|
.CE
|
|
"blah" is the optionName argument and "<specific options>"
|
|
is a space separated list of specific option words.
|
|
The function takes good care of inserting minus signs before
|
|
each option, commas after, and an "or" before the last option.
|
|
.VE
|
|
|
|
.SH "SEE ALSO"
|
|
Tcl_Close(3), Tcl_OpenFileChannel(3), Tcl_SetErrno(3), Tcl_QueueEvent(3)
|
|
|
|
.SH KEYWORDS
|
|
blocking, channel driver, channel registration, channel type, nonblocking
|