The Bzip2 class implements a bzip2 compressor and decompressor. It is compliant with bzip2 specification.
The bzip2 file format is typically used only to archive a single file. Accordingly, the operation of the class is simpler than that of the other classs.
To compress with the class, set archive_file to the name of the bzip2 file to be created, and file_decompressed_name to the name of the file to be compressed. Finally, invoke compress. To extract the file, set archive_file to the bzip2 archive and file_decompressed_name to the file where the class should extract. Finally, invoke the extract or compress method.
Example (Creating a Bzip2 File)
ZipControl.ArchiveFile = "c:\test.bz2"
ZipControl.FileDecompressedName = "c:\test.txt"
Example (Extracting from a Bzip2 File)
ZipControl.ArchiveFile = "c:\test.bz2"
ZipControl.FileDecompressedName = "c:\test.txt"
This class is an implementation based on Julian Seward's bzip2 library (http://www.bzip.org).
The following is the full list of the properties of the class with short descriptions. Click on the links for further details.
|archive_file||The name of the zip, gzip, tar, or jar archive.|
|bzip_2_data||(Decompression only) The bzip2 file contents as a byte array.|
|extract_to_path||A base path to decompress to.|
|file_decompressed_name||File name to decompress to, or compress from.|
|file_input_data||The data of the file to be compressed.|
|has_more_data||Shows whether or not there is more data in the bzip2 archive.|
The following is the full list of the methods of the class with short descriptions. Click on the links for further details.
|abort||Aborts the current operation.|
|append||Adds specified file to an existing archive.|
|compress||Creates the compressed bzip2 archive.|
|config||Sets or retrieves a configuration setting.|
|extract||Extracts the compressed file from the bzip2 archive.|
|extract_all||Extracts all files from the compressed archive.|
|reset||Resets the class.|
|scan||Scans the compressed archive.|
The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.
|on_begin_file||Fired before a file is processed.|
|on_end_file||Fired after a file is processed.|
|on_error||Information about non-fatal errors.|
|on_overwrite||Fired whenever a file exists and may be overwritten.|
|on_progress||Fired as progress is made.|
The following is a list of config settings for the class with short descriptions. Click on the links for further details.
|WriteToProgressEvent||Whether or not to write data to the Progress Event.|
|BuildInfo||Information about the product's build.|
|CodePage||The system code page used for Unicode to Multibyte translations.|
|LicenseInfo||Information about the current license.|
|ProcessIdleEvents||Whether the class uses its internal event loop to process events when the main thread is idle.|
|SelectWaitMillis||The length of time in milliseconds the class will wait when DoEvents is called if there are no events to process.|
|UseInternalSecurityAPI||Tells the class whether or not to use the system security libraries or an internal implementation.|
The name of the zip, gzip, tar, or jar archive.
def get_archive_file() -> str: ... def set_archive_file(value: str) -> None: ...
archive_file = property(get_archive_file, set_archive_file)
This property specifies the name of the archive to be read or written. This property is required when extracting files.
When compress is called, the file named by archive_file will be written; if a file of this name already exists the on_overwrite event will be fired. If archive_file is set to the empty string (""), the archive will not be written to disk, and will be provided only through the on_progress event.
The filename may be specified with or without a path. Paths may be relative or absolute, and should be specified in the format native to the host operating system. The filename should be specified with the appropriate extension (such as "zip"); an extension will not automatically be appended by the class.
If the file cannot be read, or written, as appropriate, a trappable error will be generated.
Example (Creating an Archive)
ZipControl.ArchiveFile = "c:\test.zip"
ZipControl.RecurseSubdirectories = true
Note: an archive already open for read may be closed by setting archive_file to the empty string ("").
(Decompression only) The bzip2 file contents as a byte array.
def set_bzip_2_data(value: bytes) -> None: ...
bzip_2_data = property(None, set_bzip_2_data)
Normally you should set archive_file before invoking scan or extract. If you prefer to read the bzip2 file from memory you may set bzip_2_data instead. bzip_2_data should be set to the entire contents of the bzip2 file; this will allow you to read from the bzip2 without writing any temporary files to disk.
If you would like to extract data from the archive without ever writing to disk you should also set WriteToProgressEvent to true, and after invoking scan, you should set the value of file_decompressed_name to an empty string. Then, when you invoke extract (or extract_all) the data will be provided in the on_progress event.
This property is write-only. Note that modifying a bzip2 file stored in bzip_2_data is not supported, so append will throw exceptions.
This property is write-only.
A base path to decompress to.
def get_extract_to_path() -> str: ... def set_extract_to_path(value: str) -> None: ...
extract_to_path = property(get_extract_to_path, set_extract_to_path)
Setting the extract_to_path property affects the operation of the extract and extract_all methods. Setting this property to a nonempty string will cause all decompressed files to be written to the specified path. If pathnames are given in the values of file_decompressed_name they will be regarded as relative to extract_to_path.
If the specified directory does not exist, it will be created when extraction is done.
extract_to_path should always be specified in the format native to the host operating system, and with a trailing slash or backslash. If the path is specified otherwise, it will be immediately converted and stored in the converted format. For example, "/temp" would be immediately converted to "\temp\" on a Windows system.
File name to decompress to, or compress from.
def get_file_decompressed_name() -> str: ... def set_file_decompressed_name(value: str) -> None: ...
file_decompressed_name = property(get_file_decompressed_name, set_file_decompressed_name)
file_decompressed_name contains the name of the file in the archive, as stored on the file system, outside the archive.
When compressing a file, this property should be specified with a path, if necessary, to allow the file to be found by the class. If the file cannot be found when compress is called, a trappable error will be generated, and the archive will not be correctly written.
When decompressing files, this property may be set prior to calling extract. If this property is set to the empty string when extract is called, extract will automatically set this property to an appropriate value.
Paths on the local file system should be specified in the format native to the host operating system. They may also be specified in standard (UNIX) format, in which case they will be immediately converted.
The data of the file to be compressed.
def get_file_input_data() -> bytes: ... def set_file_input_data(value: bytes) -> None: ...
file_input_data = property(get_file_input_data, set_file_input_data)
When this property is set, the class will read in the data from this property instead of reading from the file contained in the file_decompressed_name property.
Shows whether or not there is more data in the bzip2 archive.
def get_has_more_data() -> bool: ...
has_more_data = property(get_has_more_data, None)
The bzip2 format allows multiple bzip2 data members to be concatenated into a single file. However, due to the nature of the algorithm it is impossible to determine the number of data members until after the entire archive has been decompressed. The has_more_data property can be used to cycle through the archive and extract each file.
Example (Extracting Multiple Files)
ZipControl.ArchiveFile = "c:\temp.bz2"
ZipControl.ExtractToPath = "c:\extracted\"
//here you may set the file name in file_decompressed_name prior to extraction
This property is read-only.
Aborts the current operation.
def abort() -> None: ...
abort may be used to immediately interrupt compression or decompression. Any files partially written by the class will be deleted.
Adds specified file to an existing archive.
def append() -> None: ...
This method may only be used to add files to an existing archive. To add files to a new archive, compress method should be used.
Creates the compressed bzip2 archive.
def compress() -> None: ...
Invoking compress creates the archive specified by archive_file. When the method is called, the file specified by file_decompressed_name will be opened, and the file specified by archive_file will contain the compressed output.
As the data is compressed the on_progress event will be fired at regular intervals. This event may be used to stream out the bzip2 file, or to display a progress bar to the user.
Sets or retrieves a configuration setting.
def config(configuration_string: str) -> str: ...
config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.
These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the config method.
To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).
To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.
Extracts the compressed file from the bzip2 archive.
def extract() -> None: ...
Invoking extract decompresses the archive specified by archive_file. The compressed file will be extracted, and written to disk.
If archive_file ends in ".bz2", this filename, less the ".bz2" extension will be used.
If this condition does not hold, ".unzipped" will be appended to archive_file.
Extracts all files from the compressed archive.
def extract_all() -> None: ...
The on_begin_file and on_end_file events will be fired before and after each file is extracted, and the on_progress event will be fired as the data is extracted. If WriteToProgressEvent is set to true, the decompressed data will be streamed out through the on_progress event.
Resets the class.
def reset() -> None: ...
reset resets the state of the class. All properties will be set to their default values, and any files open will be closed.
Scans the compressed archive.
def scan() -> None: ...
This method will scan the bzip archive specified by archive_file. The archive will be read, and the header will be checked.
Unlike in the Zip, Tar, and Jar classs, it is never necessary to invoke this method, and it will not be automatically invoked by extract. Suggested uses for this method would be to check that the file is a bzip file.
Fired before a file is processed.
class Bzip2BeginFileEventParams(object): @property def index() -> int: ... @property def skip() -> bool: ... @skip.setter def skip(value) -> None: ... # In class Bzip2: @property def on_begin_file() -> Callable[[Bzip2BeginFileEventParams], None]: ... @on_begin_file.setter def on_begin_file(event_hook: Callable[[Bzip2BeginFileEventParams], None]) -> None: ...
on_begin_file is fired before compression or decompression begins. Index will contain 0.
You may use the Skip parameter to tell the class to skip the file when appending or decompressing.
Fired after a file is processed.
class Bzip2EndFileEventParams(object): @property def index() -> int: ... # In class Bzip2: @property def on_end_file() -> Callable[[Bzip2EndFileEventParams], None]: ... @on_end_file.setter def on_end_file(event_hook: Callable[[Bzip2EndFileEventParams], None]) -> None: ...
on_end_file is fired when compression or decompression finishes. Index will contain 0.
Information about non-fatal errors.
class Bzip2ErrorEventParams(object): @property def description() -> str: ... @property def error_code() -> int: ... @property def index() -> int: ... @property def filename() -> str: ... @property def ignore() -> bool: ... @ignore.setter def ignore(value) -> None: ... # In class Bzip2: @property def on_error() -> Callable[[Bzip2ErrorEventParams], None]: ... @on_error.setter def on_error(event_hook: Callable[[Bzip2ErrorEventParams], None]) -> None: ...
The on_error event is fired when non-fatal errors occur during compression or decompression. Note that if this event is fired during decompression this may indicate that the archive is corrupt.
By default these errors will cause the component to fail with an exception. The exception may be overridden by setting Ignore to true. This will cause the error to be ignored, the file will be skipped if necessary, and the class will continue operation.
ErrorCode will correspond to one of the following errors:
|1||Bad or missing CRC-32 checksum.|
|2||Failed to set creation date of a file.|
|111||Can't open file for read (skipping).|
Description contains a textual description of the error. Index and Filename contain the array index (where appropriate) and filename of the file being processed at the time of the error.
Fired whenever a file exists and may be overwritten.
class Bzip2OverwriteEventParams(object): @property def filename() -> str: ... @filename.setter def filename(value) -> None: ... @property def overwrite() -> bool: ... @overwrite.setter def overwrite(value) -> None: ... # In class Bzip2: @property def on_overwrite() -> Callable[[Bzip2OverwriteEventParams], None]: ... @on_overwrite.setter def on_overwrite(event_hook: Callable[[Bzip2OverwriteEventParams], None]) -> None: ...
on_overwrite is fired when a file is about to be overwritten, and would overwrite an existing file. The event is fired during decompression.
Filename contains the full name of the file, specified with its pathname.
Overwrite specifies whether or not the file will be overwritten. For Zip, Jar, and Tar, this is equal by default to the value of the overwrite_files property. For Gzip, this value defaults to true.
Either of the parameters may be changed when the event is fired. Changing the value of Overwrite will override the default behavior of the class, and cause the file to be overwritten or not overwritten, depending on the value set. If Filename is changed, the value of Overwrite will be ignored, and the file will be written with the specified name. If a file of the new name also exists this file will be silently overwritten.
Fired as progress is made.
class Bzip2ProgressEventParams(object): @property def data() -> bytes: ... @property def filename() -> str: ... @property def bytes_processed() -> int: ... @property def percent_processed() -> int: ... # In class Bzip2: @property def on_progress() -> Callable[[Bzip2ProgressEventParams], None]: ... @on_progress.setter def on_progress(event_hook: Callable[[Bzip2ProgressEventParams], None]) -> None: ...
The on_progress event is automatically fired as compression or decompression is performed. When WriteToProgressEvent is true, the output data is provided through the Data parameter, allowing for it to be streamed out.
Filename contains the name of the file being written. If no file is being written, Filename will contain an empty string, and the output data will be provided exclusively through this event.
BytesProcessed contains the total number of uncompressed bytes processed. PercentProcessed contains the percent of uncompressed bytes processed, corresponding roughly to the running time of the operation.
For Gzip extraction only, BytesProcessed and PercentProcessed will reflect the number of compressed bytes extracted, as it is generally impossible to predetermine the total uncompressed size.
If WriteToProgressEvent is false, Data will contain null.
Bzip2 Config SettingsThe class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the config method.
Bzip2 Config Settings
Whether or not to write data to the Progress Event.If WriteToProgressEvent is set to true, then all data produced through invocations
of extract, extract_all, and compress will be written to the on_progress
event as well as to disk. Applications may stream out the compressed or decompressed
data by trapping this event and copying the data.
By default, this config is set to false.
Base Config Settings
|BuildInfo: Information about the product's build.When queried, this setting will return a string containing information about the product's build.|
The system code page used for Unicode to Multibyte translations.The default code page is Unicode UTF-8 (65001).
The following is a list of valid code page identifiers:
Information about the current license.When queried, this setting will return a string containing information about the license this instance of a class is using. It will return the following information:
|ProcessIdleEvents: Whether the class uses its internal event loop to process events when the main thread is idle.If set to False, the class will not fire internal idle events. Set this to False to use the class in a background thread on Mac OS. By default, this setting is True.|
|SelectWaitMillis: The length of time in milliseconds the class will wait when DoEvents is called if there are no events to process.If there are no events to process when do_events is called, the class will wait for the amount of time specified here before returning. The default value is 20.|
|UseInternalSecurityAPI: Tells the class whether or not to use the system security libraries or an internal implementation. By default the class will use the system security libraries to perform cryptographic functions where applicable. Setting this to True tells the class to use the internal implementation instead of using the system's security API.|
The following errors may be generated by the class. Note that frequently the error message will contain more specific information than what is listed here.
Note that some non-fatal errors may be trapped and explicitly ignored in the on_error event. This will allow the class to continue operation even in case of error.
|111 Can't open file for read.|
|112 Can't open file for write.|
|113 Can't create directory.|
|114 The file is too large.|
|115 Can't create empty archive.|
|116 The archive must be scanned prior to attempting this operation.|
|117 The array index is out of range.|
|118 The maximum size of the archive has been exceeded.|
|119 The archive must be specified, or streaming must be enabled.|
|120 The component is busy.|
|124 Must specify the compressed name.|
|127 Bad CRC-32 checksum.|
|128 Unable to set file date.|
|133 File already exists in the archive.|
|150 An I/O error has occurred (details follow).|