TapeReader Class Reference

#include <TapeReader.hpp>

Public Types
enum	ReadStatus {   Normal, EndOfBlock, EndOfFile, EndOfTape,   ReadError }

Public Member Functions
	TapeReader (const char *szPath, int nSize=TapeReaderBlockSize)
virtual	~TapeReader ()
int	read (ReadStatus &status, void *buffer, int req_size=0)
void	undo_read (void *buffer, int undo_size)
void	set_block_mode (bool bFlag)
bool	get_block_mode () const
int	get_max_block_size () const
void	set_max_errors (int nErrors)
int	get_max_errors () const
bool	is_tape () const

Protected Member Functions
int	read (void *buf, int req_size)

Static Protected Member Functions
static int	open (const char *szPath, bool &bTape)

Protected Attributes
int	fdTape
bool	bBlockMode
bool	bTapeDevice
ReadStatus	ePrevStatus
int	nMaxBlockSize
int	nMaxErrors
char *	pBlockBuffer
int	nDataOffset
int	nDataSize

Detailed Description

Object for reading the tape or several files.

Member Enumeration Documentation

enum TapeReader::ReadStatus

Enumerator
Normal	All data are in buffer.
EndOfBlock	End of block is reached, so actual data are shorter than expected.
EndOfFile	Data are absent since end of tape file is reached.
EndOfTape	Data are absent since end to end of tape is reached.
ReadError	Data are absent due to error.

Constructor & Destructor Documentation

TapeReader::TapeReader	(	const char *	szPath,
		int	nSize = TapeReaderBlockSize
	)

Create object for reading given tape (or other medium). Maximum block size is set here for tape devices too (64K by default).

In case of disk file reading szPath is a mask like /path/A*B for matching all files "AaB", "A12B", "AabcB" etc in directory /path. Each file is supposed to be equivalent to tape file. Block boundary is not detected. Buffer size is allocated to the maximum size among matched files. Unique subpart of filename of the current file can be accessed via file_signature().

virtual TapeReader::~TapeReader ( )

virtual

Destroy the object and release all catched resources.

Member Function Documentation

bool TapeReader::get_block_mode

(

)

const

Get block mode flag. True means reading is performed by blocks. False means no EndOfBlock status will be ever returned by read() method.

int TapeReader::get_max_block_size

(

)

const

Get maximum tape block size in bytes.

int TapeReader::get_max_errors

(

)

const

Get maximum number of reading errors.

bool TapeReader::is_tape

(

)

const

Get the tape device flag. True in case of tape device and false in case of other (normal) file.

static int TapeReader::open ( const char *  szPath, bool &  bTape  )

staticprotected

Open the tape or other medium and return file descriptor. bTape contains whether file is tape (character oriented device) or other type. 'static' since the method does not use and touch internal object state.

int TapeReader::read	(	ReadStatus &	status,
		void *	buffer,
		int	req_size = 0
	)

Read requested number of bytes inside the block (in case of block mode is on). Actual number of bytes in data buffer is returned.

int TapeReader::read ( void *  buf, int  req_size  )

protected

Read needed number of bytes from file. Tries to read several times in case of tape. Returns number of actually bytes read or error hint (-1). errno contains error code as usual.

void TapeReader::set_block_mode

(

bool

bFlag

)

Set block mode flag. True means reading is performed by blocks. False means no EndOfBlock status will be ever returned by read() method.

void TapeReader::set_max_errors

(

int

nErrors

)

Setup maximum number of reading errors until ReadError will be returned.

void TapeReader::undo_read	(	void *	buffer,
		int	undo_size
	)

Put given bytes back to read buffer. Number of bytes should be less than size of internal block.

Member Data Documentation

bool TapeReader::bBlockMode

protected

Block mode flag.

bool TapeReader::bTapeDevice

protected

Tape device flag.

ReadStatus TapeReader::ePrevStatus

protected

Previous actual device read status.

int TapeReader::fdTape

protected

File descriptor of opened tape

int TapeReader::nDataOffset

protected

Offset to unread data bytes in the buffer.

int TapeReader::nDataSize

protected

Actual number of bytes in the buffer.

int TapeReader::nMaxBlockSize

protected

Maximum length of tape record.

int TapeReader::nMaxErrors

protected

Maximum allowed number of read errors.

char* TapeReader::pBlockBuffer

protected

Preallocated buffer for the most long tape record.

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

• /net/opt/univers/ubp-i-15.3-centos7-x64.urij/include/mix/TapeReader.hpp