lat::TarInputStream Class Reference

Read a TAR archive straight off an input stream. More...

Inheritance diagram for lat::TarInputStream:

Detailed Description

Read a TAR archive straight off an input stream.

Notes:

If a the same file (dev/inode pair) appears several times in the archive, the first time it appears as a regular file; the second and subsequent references appear as as a link.

The archive may include entries used by TAR to store info for itself (labels), but these are not supported.

Tar archives consist of a series of 512-byte blocks. Each entry in the archive has a header record followed by file contents padded to block size. The entire archive may be, but is not required to be padded to "record size", which is normally 20 blocks (= the blocking factor); the actual record size depends on tape media used or simply parameters to the program that created the archive. Hence the archive may end with an arbitrary number of zero blocks. (Note: if archives have been concatenated, there may be zero blocks in between archives.) The reader detects the all-zeros record as the end of the archive marker and stops reading at that point. (Lack of the all-zeroes end-of-archive marker is not considered an error; the last member is not required to be full block size either.) There may be more such zero blocks (= archive padded to tape record size) left in the input stream. If the archive is embedded in another stream, the embedder needs to take this into account, for example by knowing the exact size and the skipping what this stream did not read, or by continuing to read as long as there are null blocks and then pushing the rest back.

This stream is not directly usable with real tape devices. For one, someone has to determine the tape record size. Secondly this stream does not make atomic writes of the tape record size. (The archive is rounded up to the default record size of 20 blocks.)

This stream does not work on non-blocking input.

Definition at line 66 of file TarInputStream.h.

lat::TarInputStream::TarInputStream ( InputStream * input )

lat::TarInputStream::~TarInputStream ( void )

virtual IOSize lat::TarInputStream::available ( void ) [virtual]

virtual void lat::TarInputStream::close ( void ) [virtual]

virtual void lat::TarInputStream::closeMember ( void ) [virtual]

std::string lat::TarInputStream::extractStr	(	const void *	buf,
		IOSize	max
	)			`[private]`

virtual TarMember* lat::TarInputStream::nextMember ( void ) [virtual]

virtual IOSize lat::TarInputStream::read	(	void *	into,
		IOSize	n
	)			`[virtual]`

virtual void lat::TarInputStream::reset ( void ) [virtual]

virtual IOSize lat::TarInputStream::skip ( IOSize n ) [virtual]

bool lat::TarInputStream::validate	(	const void *	buf,
		IOSize	length
	)			`[private]`

Definition at line 88 of file TarInputStream.h.

Definition at line 90 of file TarInputStream.h.

Definition at line 89 of file TarInputStream.h.

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

Generated on Tue Jun 9 18:48:36 2009 for CMSSW by

1.5.4


Public Member Functions
virtual IOSize	available (void)
virtual void	close (void)
virtual void	closeMember (void)
virtual TarMember *	nextMember (void)
virtual IOSize	read (void *into, IOSize n)
virtual void	reset (void)
virtual IOSize	skip (IOSize n)
	TarInputStream (InputStream *input)
	~TarInputStream (void)
Private Member Functions
std::string	extractStr (const void *buf, IOSize max)
bool	validate (const void *buf, IOSize length)
Private Attributes
TarMember *	m_current
IOOffset	m_padding
IOOffset	m_remaining