A channel that does nothing. More...

#include <channel.h>

Inheritance diagram for PNullChannel:

Collaboration diagram for PNullChannel:

Public Member Functions
	PNullChannel ()

virtual PString	GetName () const
	Get the platform and I/O channel type name of the channel. More...

virtual PBoolean	Read (void *, PINDEX)
	Low level read from the channel. More...

virtual PBoolean	Write (const void *, PINDEX)
	Low level write to the channel. More...

Public Member Functions inherited from PChannel
PBoolean	SetErrorValues (Errors errorCode, int osError, ErrorGroup group=LastGeneralError)
	Set error values to those specified. More...

virtual Comparison	Compare (const PObject &obj) const
	Get the relative rank of the two strings. More...

virtual PINDEX	HashFunction () const
	Calculate a hash value for use in sets and dictionaries. More...

virtual PBoolean	IsOpen () const
	Determine if the channel is currently open. More...

virtual P_INT_PTR	GetHandle () const
	Get the integer operating system handle for the channel. More...

FILE *	FDOpen (const char *mode)
	Re-open the device using the stdio library. More...

virtual PChannel *	GetBaseReadChannel () const
	Get the base channel of channel indirection using PIndirectChannel. More...

virtual PChannel *	GetBaseWriteChannel () const
	Get the base channel of channel indirection using PIndirectChannel. More...

virtual bool	CloseBaseReadChannel ()
	Close the base channel of channel indirection using PIndirectChannel. More...

virtual bool	CloseBaseWriteChannel ()
	Close the base channel of channel indirection using PIndirectChannel. More...

void	SetReadTimeout (const PTimeInterval &time)
	Set the timeout for read operations. More...

PTimeInterval	GetReadTimeout () const
	Get the timeout for read operations. More...

virtual PINDEX	GetLastReadCount () const
	Get the number of bytes read by the last Read() call. More...

virtual PINDEX	SetLastReadCount (PINDEX count)

virtual int	ReadChar ()
	Read a single character from the channel. More...

PBoolean	ReadBlock (void *buf, PINDEX len)
	Read len bytes into the buffer from the channel. More...

PString	ReadString (PINDEX len)
	Read `len` character into a string from the channel. More...

void	SetWriteTimeout (const PTimeInterval &time)
	Set the timeout for write operations to complete. More...

PTimeInterval	GetWriteTimeout () const
	Get the timeout for write operations to complete. More...

virtual PBoolean	Write (const void buf, PINDEX len, const void )
	Low level write to the channel with marker. More...

virtual PINDEX	GetLastWriteCount () const
	Get the number of bytes written by the last Write() call. More...

virtual PINDEX	SetLastWriteCount (PINDEX count)

PBoolean	WriteChar (int c)
	Write a single character to the channel. More...

PBoolean	WriteString (const PString &str)
	Write a string to the channel. More...

	~PChannel ()
	Close down the channel. More...

Errors	GetErrorCode (ErrorGroup group=NumErrorGroups) const
	Get normalised error code. More...

int	GetErrorNumber (ErrorGroup group=NumErrorGroups) const
	Get OS errro code. More...

virtual PString	GetErrorText (ErrorGroup group=NumErrorGroups) const
	Get error message description. More...

virtual bool	ReadAsync (AsyncContext &context)
	Begin an asynchronous read from channel. More...

virtual void	OnReadComplete (AsyncContext &context)
	User callback function for when a `ReadAsync()` call has completed or timed out. More...

virtual bool	WriteAsync (AsyncContext &context)
	Begin an asynchronous write from channel. More...

virtual void	OnWriteComplete (AsyncContext &context)
	User callback function for when a WriteAsync() call has completed or timed out. More...

virtual PBoolean	Close ()
	Close the channel, shutting down the link to the data source. More...

virtual PBoolean	Shutdown (ShutdownValue option)
	Close one or both of the data streams associated with a channel. More...

virtual bool	SetLocalEcho (bool localEcho)
	Set local echo mode. More...

virtual bool	FlowControl (const void *flowData)
	Flow Control information Pass data to the channel for flowControl determination. More...

PBoolean	SetBufferSize (PINDEX newSize)
	Set the iostream buffer size for reads and writes. More...

PBoolean	SendCommandString (const PString &command)
	Send a command meta-string. More...

void	AbortCommandString ()
	Abort a command string that is in progress. More...

Public Member Functions inherited from PObject
__inline unsigned	GetTraceContextIdentifier () const
	Get PTRACE context identifier. More...

__inline void	SetTraceContextIdentifier (unsigned id)

__inline void	SetTraceContextIdentifier (const PObject &obj)

__inline void	SetTraceContextIdentifier (const PObject *obj)

__inline void	CopyTraceContextIdentifier (PObject &obj) const

__inline void	CopyTraceContextIdentifier (PObject *obj) const

virtual	~PObject ()

__inline const char *	GetClass () const

__inline bool	IsClass (const char *name) const

__inline const PObject *	PTraceObjectInstance () const

virtual PObject *	Clone () const
	Create a copy of the class on the heap. More...

template<class CLS >
CLS *	CloneAs () const
	As for Clone() but converts to specified type. More...

virtual Comparison	CompareObjectMemoryDirect (const PObject &obj) const
	Determine the byte wise comparison of two objects. More...

bool	operator== (const PObject &obj) const
	Compare the two objects. More...

bool	operator!= (const PObject &obj) const
	Compare the two objects. More...

bool	operator< (const PObject &obj) const
	Compare the two objects. More...

bool	operator> (const PObject &obj) const
	Compare the two objects. More...

bool	operator<= (const PObject &obj) const
	Compare the two objects. More...

bool	operator>= (const PObject &obj) const
	Compare the two objects. More...

virtual void	PrintOn (ostream &strm) const
	Output the contents of the object to the stream. More...

virtual void	ReadFrom (istream &strm)
	Input the contents of the object from the stream. More...

Additional Inherited Members
Public Types inherited from PChannel
enum	PXBlockType { PXReadBlock, PXWriteBlock, PXAcceptBlock, PXConnectBlock }

enum	Errors { NoError, NotFound, FileExists, DiskFull, AccessDenied, DeviceInUse, BadParameter, NoMemory, NotOpen, Timeout, Interrupted, BufferTooSmall, Miscellaneous, ProtocolFailure, Unavailable, NumNormalisedErrors }
	Normalised error codes. More...

enum	ErrorGroup { LastReadError, LastWriteError, LastGeneralError, NumErrorGroups }
	Error groups. More...

typedef PNotifierTemplate < PChannel::AsyncContext & >	AsyncNotifier

enum	ShutdownValue { ShutdownRead = 0, ShutdownWrite = 1, ShutdownReadAndWrite = 2 }

Public Types inherited from PObject
enum	Comparison { LessThan = -1, EqualTo = 0, GreaterThan = 1 }
	Result of the comparison operation performed by the `Compare()` function. More...

Static Public Member Functions inherited from PChannel
static PString	GetErrorText (Errors lastError, int osError=0)
	Get error message description. More...

Static Public Member Functions inherited from PObject
static __inline void	CopyTraceContextIdentifier (PObject &to, const PObject &from)

static __inline void	CopyTraceContextIdentifier (PObject &to, const PObject *from)

static __inline void	CopyTraceContextIdentifier (PObject *to, const PObject &from)

static __inline void	CopyTraceContextIdentifier (PObject to, const PObject from)

static __inline const char *	Class ()

static __inline const PObject *	PTraceObjectInstance (const char *)

static __inline const PObject *	PTraceObjectInstance (const PObject *obj)

template<typename T >
static Comparison	Compare2 (T v1, T v2)
	Compare two types, returning Comparison type. More...

static Comparison	InternalCompareObjectMemoryDirect (const PObject obj1, const PObject obj2, PINDEX size)
	Internal function caled from CompareObjectMemoryDirect() More...

Protected Member Functions inherited from PChannel
	PChannel (const PChannel &)

PChannel &	operator= (const PChannel &)

virtual PBoolean	ConvertOSError (P_INT_PTR libcReturnValue, ErrorGroup group=LastGeneralError)
	Convert an operating system error into platform independent error. More...

int	ReadCharWithTimeout (PTimeInterval &timeout)
	Read a character with specified timeout. More...

PBoolean	ReceiveCommandString (int nextChar, const PString &reply, PINDEX &pos, PINDEX start)

bool	CheckNotOpen ()

virtual int	os_errno () const

PBoolean	PXSetIOBlock (PXBlockType type, const PTimeInterval &timeout)

P_INT_PTR	GetOSHandleAsInt () const

int	PXClose ()

	PDECLARE_MUTEX (px_threadMutex)

	PDECLARE_MUTEX (px_writeMutex)

	PChannel ()
	Create the channel. More...

Protected Member Functions inherited from PObject
	PObject ()
	Constructor for PObject, made protected so cannot ever create one on its own. More...

Protected Attributes inherited from PChannel
PTimeInterval	readTimeout
	Timeout for read operations. More...

PTimeInterval	writeTimeout
	Timeout for write operations. More...

atomic< P_INT_PTR >	os_handle
	The operating system file handle return by standard open() function. More...

PThreadLocalStorage< Status >	m_status [NumErrorGroups+1]

PXBlockType	px_lastBlockType

PThread *	px_readThread

PThread *	px_writeThread

PThread *	px_selectThread [3]

PCriticalSection	px_selectMutex [3]

Protected Attributes inherited from PObject
unsigned	m_traceContextIdentifier

Detailed Description

A channel that does nothing.

Constructor & Destructor Documentation

PNullChannel::PNullChannel ( )

Member Function Documentation

virtual PString PNullChannel::GetName ( ) const

inlinevirtual

Get the platform and I/O channel type name of the channel.

For example, it would return the filename in PFile type channels.

Returns: the name of the channel.

Implements PChannel.

virtual PBoolean PNullChannel::Read	(	void *	buf,
		PINDEX	len
	)

virtual

Low level read from the channel.

This function may block until the requested number of characters were read or the read timeout was reached. The GetLastReadCount() function returns the actual number of bytes read.

The GetErrorCode() function should be consulted after Read() returns false to determine what caused the failure.

Returns: true indicates that at least one character was read from the channel. false means no bytes were read due to timeout or some other I/O error.

Reimplemented from PChannel.

virtual PBoolean PNullChannel::Write	(	const void *	buf,
		PINDEX	len
	)

virtual

Low level write to the channel.

This function will block until the requested number of characters are written or the write timeout is reached. The GetLastWriteCount() function returns the actual number of bytes written.

The GetErrorCode() function should be consulted after Write() returns false to determine what caused the failure.

Returns: true if at least len bytes were written to the channel.

Reimplemented from PChannel.

The documentation for this class was generated from the following file:

channel.h

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation