OLGzipOutStream Class Reference
[Streams]

A stream for zlib compression that writes data in the gzip format. More...

#import <ObjecitveLib/GzipOutStream.h>

Inheritance diagram for OLGzipOutStream:

[legend]List of all members.

Public Member Functions
(void)	- addExtraField:withBytes:count:
	Add an extra field.
(void)	- close
	Close the stream.
(void)	- freeStreamResources
	Free the stream's resources.
(void)	- markModificationTime
	Set the modification time to now.
(void)	- setComment:
	Set the comment of the gzip data.
(void)	- setCommentText:
	Set the comment of the gzip data.
(void)	- setOriginalFileName:includeModificationTime:
	Set the original file name of the data.
(void)	- setOriginalFileNameText:includeModificationTime:
	Set the original file name of the data.
(unsigned)	- writeBytes:count:
	Write a sequence of bytes to the stream.
Initializers and Deallocators
(id)	- initWithOutStream:compressionLevel:bufferSize:writeZlibHeader:
	Initialize the compression stream.
Static Public Member Functions
(id)	+ streamWithOutStream:
	Create and return a new compression stream.
(id)	+ streamWithOutStream:compressionLevel:
	Create and return a new compression stream.
Protected Attributes
uint8_t *	commentData
	The gzip comment.
uint32_t	crc
	The CRC-32 value of the data.
OLDataOutStream *	extraFields
	The extra fields.
uint8_t *	fileNameData
	The original file name associated with the data.
BOOL	headerWritten
	Whether the header has been written.
uint32_t	modTime
	The modification time.
BOOL	trailerWritten
	Whether the trailer has been written.

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Detailed Description

A stream for zlib compression that writes data in the gzip format.

The data are written using the format described in RFC 1952, and can be read by the command-line tool gzip.

See also:

OLGzipInStream, OLZlibOutStream

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Member Function Documentation

- (void) addExtraField:		(const char *)	identifier
withBytes:		(const uint8_t *)	buf
count:		(unsigned)	num

Add an extra field.

The bytes in buf are associated with identifier in the gzip data.

Note:

If this message is sent after the first bytes have been written to the stream, then adding an extra field will have no effect.

Precondition:

The length of the string identifier must be 2.

Exceptions:

OLInputOutputException

if the length of identifier is not 2

Parameters:

	identifier	the identifier of the extra field
	buf	the bytes associated with the extra field
	num	the number of bytes in buffer

- (void) close

Close the stream.

After receiving this message the stream will no longer be available for writing.

Exceptions:

OLInputOutputException

if there is an error closing the stream

Reimplemented from OLZlibOutStream.

- (void) freeStreamResources

Free the stream's resources.

This secondary freeing method is necessary to allow the reference count to be properly manipulated from within the normal free (OLReferenceCountedStream) method.

Note:

All sublcasses that allocate resources must implement this method to free those resources and call [super freeStreamResources].

Reimplemented from OLZlibOutStream.

- (id) initWithOutStream:		(OLOutStream *)	underStream
compressionLevel:		(int)	level
bufferSize:		(unsigned)	size
writeZlibHeader:		(BOOL)	zlibHeader

Initialize the compression stream.

The the given compression level and buffer size. The given out stream underStream is the next lower stream in the stream stack. If zlibHeader is YES, then the zlib header will be written to the stream, otherwise it will not be written.

Attention:

You probably do not want to use this initializer. This initializer is overriden so that the argument zlibHeader will always be NO, as the gzip data format cannot be used with the zlib header.

Precondition:

The indicated compression level must be in the range [0,9].

Exceptions:

	OLInvalidArgumentException	if the compression level is not in the range [0,9]
	OLInputOutputException	if the stream cannot be created for deflation

Parameters:

	underStream	the next lower stream in the stack
	level	the compression level which must be in the range [0,9]
	size	the size of the internal buffer
	zlibHeader	it doesn't matter what you use, as it will be overridden

Returns:

a reference to this stream

Reimplemented from OLZlibOutStream.

- (void) markModificationTime

Set the modification time to now.

This message should be sent if a modification time is desired, but there is no original file name in the data. The time is set to the current time.

Note:

If this message is sent after the first bytes have been written to the stream, then setting the modification time will have no effect.

- (void) setComment:

(const char *)

comment

Set the comment of the gzip data.

The string comment is set as the data's comment.

Note:

The data in comment must be encoded using the ISO 8859-1 encoding as described in RFC 1952.

If this message is sent after the first bytes have been written to the stream, then setting the comment will have no effect.

Parameters:

comment

the gzip data's new comment

- (void) setCommentText:

(OLText *)

comment

Set the comment of the gzip data.

The string comment is set as the data's comment.

Note:

If this message is sent after the first bytes have been written to the stream, then setting the comment will have no effect.

Parameters:

comment

the gzip data's new comment

- (void) setOriginalFileName:		(const char *)	name
includeModificationTime:		(BOOL)	mtime

Set the original file name of the data.

To preserve the original file name when the data are extracted this message can be sent. Also, to set the modification time of the original file name, the arguement mtime can be YES, in which case the modification time of the gzip stream will be set to the modification time of the file at name.

Note:

The data in name must be encoded using the ISO 8859-1 encoding as described in RFC 1952.

If this message is sent after the first bytes have been written to the stream, then setting the file name will have no effect.

Precondition:

The file name should not contain any directories.

Parameters:

	name	the name of the original file
	mtime	YES if the modification time should be set, NO otherwise

- (void) setOriginalFileNameText:		(OLText *)	name
includeModificationTime:		(BOOL)	mtime

Set the original file name of the data.

To preserve the original file name when the data are extracted this message can be sent. Also, to set the modification time of the original file name, the arguement mtime can be YES, in which case the modification time of the gzip stream will be set to the modification time of the file at name.

Note:

If this message is sent after the first bytes have been written to the stream, then setting the file name will have no effect.

Precondition:

The file name should not contain any directories.

Parameters:

	name	the name of the original file
	mtime	YES if the modification time should be set, NO otherwise

+ (id) streamWithOutStream:

(OLOutStream *)

underStream

Create and return a new compression stream.

The stream uses the default compression level and a buffer size of 1,024. The given out stream underStream is the next lower stream in the stream stack.

Note:

If OpenStep is present the returned object will be autoreleased before being returned.

Exceptions:

OLInputOutputException

if the stream cannot be created for deflation

Parameters:

underStream

the next lower stream in the stack

Returns:

a reference to the newly created stream

Reimplemented from OLZlibOutStream.

+ (id) streamWithOutStream:		(OLOutStream *)	underStream
compressionLevel:		(int)	level

Create and return a new compression stream.

The stream uses the given compression level and a buffer size of 1,024. The given out stream underStream is the next lower stream in the stream stack.

Precondition:

The indicated compression level must be in the range [0,9].

Note:

If OpenStep is present the returned object will be autoreleased before being returned.

Exceptions:

	OLInvalidArgumentException	if the compression level is not in the range [0,9]
	OLInputOutputException	if the stream cannot be created for deflation

Parameters:

	underStream	the next lower stream in the stack
	level	the compression level which must be in the range [0,9]

Returns:

a reference to the newly created stream

Reimplemented from OLZlibOutStream.

- (unsigned) writeBytes:		(const uint8_t *)	bytes
count:		(unsigned)	num

Write a sequence of bytes to the stream.

Compress up to num bytes and return the number actually written.

Exceptions:

OLInputOutputException

if there is an error writing to the stream

Parameters:

	bytes	the bytes to write
	num	the number of bytes to write

Returns:

the number of bytes written

Reimplemented from OLZlibOutStream.

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Member Data Documentation

- (uint8_t*) commentData [protected]

The gzip comment.

- (uint32_t) crc [protected]

The CRC-32 value of the data.

- (OLDataOutStream*) extraFields [protected]

The extra fields.

- (uint8_t*) fileNameData [protected]

The original file name associated with the data.

- (BOOL) headerWritten [protected]

Whether the header has been written.

- (uint32_t) modTime [protected]

The modification time.

- (BOOL) trailerWritten [protected]

Whether the trailer has been written.

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

• GzipOutStream.h

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Generated Sun Apr 22 15:18:34 2007, © 2004-2007 Will Mason