mirror of
https://github.com/python/cpython
synced 2024-09-05 08:17:45 +00:00
357 lines
13 KiB
Python
357 lines
13 KiB
Python
"""Interface to the liblzma compression library.
|
|
|
|
This module provides a class for reading and writing compressed files,
|
|
classes for incremental (de)compression, and convenience functions for
|
|
one-shot (de)compression.
|
|
|
|
These classes and functions support both the XZ and legacy LZMA
|
|
container formats, as well as raw compressed data streams.
|
|
"""
|
|
|
|
__all__ = [
|
|
"CHECK_NONE", "CHECK_CRC32", "CHECK_CRC64", "CHECK_SHA256",
|
|
"CHECK_ID_MAX", "CHECK_UNKNOWN",
|
|
"FILTER_LZMA1", "FILTER_LZMA2", "FILTER_DELTA", "FILTER_X86", "FILTER_IA64",
|
|
"FILTER_ARM", "FILTER_ARMTHUMB", "FILTER_POWERPC", "FILTER_SPARC",
|
|
"FORMAT_AUTO", "FORMAT_XZ", "FORMAT_ALONE", "FORMAT_RAW",
|
|
"MF_HC3", "MF_HC4", "MF_BT2", "MF_BT3", "MF_BT4",
|
|
"MODE_FAST", "MODE_NORMAL", "PRESET_DEFAULT", "PRESET_EXTREME",
|
|
|
|
"LZMACompressor", "LZMADecompressor", "LZMAFile", "LZMAError",
|
|
"open", "compress", "decompress", "is_check_supported",
|
|
]
|
|
|
|
import builtins
|
|
import io
|
|
import os
|
|
from _lzma import *
|
|
from _lzma import _encode_filter_properties, _decode_filter_properties
|
|
import _compression
|
|
|
|
|
|
_MODE_CLOSED = 0
|
|
_MODE_READ = 1
|
|
# Value 2 no longer used
|
|
_MODE_WRITE = 3
|
|
|
|
|
|
class LZMAFile(_compression.BaseStream):
|
|
|
|
"""A file object providing transparent LZMA (de)compression.
|
|
|
|
An LZMAFile can act as a wrapper for an existing file object, or
|
|
refer directly to a named file on disk.
|
|
|
|
Note that LZMAFile provides a *binary* file interface - data read
|
|
is returned as bytes, and data to be written must be given as bytes.
|
|
"""
|
|
|
|
def __init__(self, filename=None, mode="r", *,
|
|
format=None, check=-1, preset=None, filters=None):
|
|
"""Open an LZMA-compressed file in binary mode.
|
|
|
|
filename can be either an actual file name (given as a str,
|
|
bytes, or PathLike object), in which case the named file is
|
|
opened, or it can be an existing file object to read from or
|
|
write to.
|
|
|
|
mode can be "r" for reading (default), "w" for (over)writing,
|
|
"x" for creating exclusively, or "a" for appending. These can
|
|
equivalently be given as "rb", "wb", "xb" and "ab" respectively.
|
|
|
|
format specifies the container format to use for the file.
|
|
If mode is "r", this defaults to FORMAT_AUTO. Otherwise, the
|
|
default is FORMAT_XZ.
|
|
|
|
check specifies the integrity check to use. This argument can
|
|
only be used when opening a file for writing. For FORMAT_XZ,
|
|
the default is CHECK_CRC64. FORMAT_ALONE and FORMAT_RAW do not
|
|
support integrity checks - for these formats, check must be
|
|
omitted, or be CHECK_NONE.
|
|
|
|
When opening a file for reading, the *preset* argument is not
|
|
meaningful, and should be omitted. The *filters* argument should
|
|
also be omitted, except when format is FORMAT_RAW (in which case
|
|
it is required).
|
|
|
|
When opening a file for writing, the settings used by the
|
|
compressor can be specified either as a preset compression
|
|
level (with the *preset* argument), or in detail as a custom
|
|
filter chain (with the *filters* argument). For FORMAT_XZ and
|
|
FORMAT_ALONE, the default is to use the PRESET_DEFAULT preset
|
|
level. For FORMAT_RAW, the caller must always specify a filter
|
|
chain; the raw compressor does not support preset compression
|
|
levels.
|
|
|
|
preset (if provided) should be an integer in the range 0-9,
|
|
optionally OR-ed with the constant PRESET_EXTREME.
|
|
|
|
filters (if provided) should be a sequence of dicts. Each dict
|
|
should have an entry for "id" indicating ID of the filter, plus
|
|
additional entries for options to the filter.
|
|
"""
|
|
self._fp = None
|
|
self._closefp = False
|
|
self._mode = _MODE_CLOSED
|
|
|
|
if mode in ("r", "rb"):
|
|
if check != -1:
|
|
raise ValueError("Cannot specify an integrity check "
|
|
"when opening a file for reading")
|
|
if preset is not None:
|
|
raise ValueError("Cannot specify a preset compression "
|
|
"level when opening a file for reading")
|
|
if format is None:
|
|
format = FORMAT_AUTO
|
|
mode_code = _MODE_READ
|
|
elif mode in ("w", "wb", "a", "ab", "x", "xb"):
|
|
if format is None:
|
|
format = FORMAT_XZ
|
|
mode_code = _MODE_WRITE
|
|
self._compressor = LZMACompressor(format=format, check=check,
|
|
preset=preset, filters=filters)
|
|
self._pos = 0
|
|
else:
|
|
raise ValueError("Invalid mode: {!r}".format(mode))
|
|
|
|
if isinstance(filename, (str, bytes, os.PathLike)):
|
|
if "b" not in mode:
|
|
mode += "b"
|
|
self._fp = builtins.open(filename, mode)
|
|
self._closefp = True
|
|
self._mode = mode_code
|
|
elif hasattr(filename, "read") or hasattr(filename, "write"):
|
|
self._fp = filename
|
|
self._mode = mode_code
|
|
else:
|
|
raise TypeError("filename must be a str, bytes, file or PathLike object")
|
|
|
|
if self._mode == _MODE_READ:
|
|
raw = _compression.DecompressReader(self._fp, LZMADecompressor,
|
|
trailing_error=LZMAError, format=format, filters=filters)
|
|
self._buffer = io.BufferedReader(raw)
|
|
|
|
def close(self):
|
|
"""Flush and close the file.
|
|
|
|
May be called more than once without error. Once the file is
|
|
closed, any other operation on it will raise a ValueError.
|
|
"""
|
|
if self._mode == _MODE_CLOSED:
|
|
return
|
|
try:
|
|
if self._mode == _MODE_READ:
|
|
self._buffer.close()
|
|
self._buffer = None
|
|
elif self._mode == _MODE_WRITE:
|
|
self._fp.write(self._compressor.flush())
|
|
self._compressor = None
|
|
finally:
|
|
try:
|
|
if self._closefp:
|
|
self._fp.close()
|
|
finally:
|
|
self._fp = None
|
|
self._closefp = False
|
|
self._mode = _MODE_CLOSED
|
|
|
|
@property
|
|
def closed(self):
|
|
"""True if this file is closed."""
|
|
return self._mode == _MODE_CLOSED
|
|
|
|
def fileno(self):
|
|
"""Return the file descriptor for the underlying file."""
|
|
self._check_not_closed()
|
|
return self._fp.fileno()
|
|
|
|
def seekable(self):
|
|
"""Return whether the file supports seeking."""
|
|
return self.readable() and self._buffer.seekable()
|
|
|
|
def readable(self):
|
|
"""Return whether the file was opened for reading."""
|
|
self._check_not_closed()
|
|
return self._mode == _MODE_READ
|
|
|
|
def writable(self):
|
|
"""Return whether the file was opened for writing."""
|
|
self._check_not_closed()
|
|
return self._mode == _MODE_WRITE
|
|
|
|
def peek(self, size=-1):
|
|
"""Return buffered data without advancing the file position.
|
|
|
|
Always returns at least one byte of data, unless at EOF.
|
|
The exact number of bytes returned is unspecified.
|
|
"""
|
|
self._check_can_read()
|
|
# Relies on the undocumented fact that BufferedReader.peek() always
|
|
# returns at least one byte (except at EOF)
|
|
return self._buffer.peek(size)
|
|
|
|
def read(self, size=-1):
|
|
"""Read up to size uncompressed bytes from the file.
|
|
|
|
If size is negative or omitted, read until EOF is reached.
|
|
Returns b"" if the file is already at EOF.
|
|
"""
|
|
self._check_can_read()
|
|
return self._buffer.read(size)
|
|
|
|
def read1(self, size=-1):
|
|
"""Read up to size uncompressed bytes, while trying to avoid
|
|
making multiple reads from the underlying stream. Reads up to a
|
|
buffer's worth of data if size is negative.
|
|
|
|
Returns b"" if the file is at EOF.
|
|
"""
|
|
self._check_can_read()
|
|
if size < 0:
|
|
size = io.DEFAULT_BUFFER_SIZE
|
|
return self._buffer.read1(size)
|
|
|
|
def readline(self, size=-1):
|
|
"""Read a line of uncompressed bytes from the file.
|
|
|
|
The terminating newline (if present) is retained. If size is
|
|
non-negative, no more than size bytes will be read (in which
|
|
case the line may be incomplete). Returns b'' if already at EOF.
|
|
"""
|
|
self._check_can_read()
|
|
return self._buffer.readline(size)
|
|
|
|
def write(self, data):
|
|
"""Write a bytes object to the file.
|
|
|
|
Returns the number of uncompressed bytes written, which is
|
|
always the length of data in bytes. Note that due to buffering,
|
|
the file on disk may not reflect the data written until close()
|
|
is called.
|
|
"""
|
|
self._check_can_write()
|
|
if isinstance(data, (bytes, bytearray)):
|
|
length = len(data)
|
|
else:
|
|
# accept any data that supports the buffer protocol
|
|
data = memoryview(data)
|
|
length = data.nbytes
|
|
|
|
compressed = self._compressor.compress(data)
|
|
self._fp.write(compressed)
|
|
self._pos += length
|
|
return length
|
|
|
|
def seek(self, offset, whence=io.SEEK_SET):
|
|
"""Change the file position.
|
|
|
|
The new position is specified by offset, relative to the
|
|
position indicated by whence. Possible values for whence are:
|
|
|
|
0: start of stream (default): offset must not be negative
|
|
1: current stream position
|
|
2: end of stream; offset must not be positive
|
|
|
|
Returns the new file position.
|
|
|
|
Note that seeking is emulated, so depending on the parameters,
|
|
this operation may be extremely slow.
|
|
"""
|
|
self._check_can_seek()
|
|
return self._buffer.seek(offset, whence)
|
|
|
|
def tell(self):
|
|
"""Return the current file position."""
|
|
self._check_not_closed()
|
|
if self._mode == _MODE_READ:
|
|
return self._buffer.tell()
|
|
return self._pos
|
|
|
|
|
|
def open(filename, mode="rb", *,
|
|
format=None, check=-1, preset=None, filters=None,
|
|
encoding=None, errors=None, newline=None):
|
|
"""Open an LZMA-compressed file in binary or text mode.
|
|
|
|
filename can be either an actual file name (given as a str, bytes,
|
|
or PathLike object), in which case the named file is opened, or it
|
|
can be an existing file object to read from or write to.
|
|
|
|
The mode argument can be "r", "rb" (default), "w", "wb", "x", "xb",
|
|
"a", or "ab" for binary mode, or "rt", "wt", "xt", or "at" for text
|
|
mode.
|
|
|
|
The format, check, preset and filters arguments specify the
|
|
compression settings, as for LZMACompressor, LZMADecompressor and
|
|
LZMAFile.
|
|
|
|
For binary mode, this function is equivalent to the LZMAFile
|
|
constructor: LZMAFile(filename, mode, ...). In this case, the
|
|
encoding, errors and newline arguments must not be provided.
|
|
|
|
For text mode, an LZMAFile object is created, and wrapped in an
|
|
io.TextIOWrapper instance with the specified encoding, error
|
|
handling behavior, and line ending(s).
|
|
|
|
"""
|
|
if "t" in mode:
|
|
if "b" in mode:
|
|
raise ValueError("Invalid mode: %r" % (mode,))
|
|
else:
|
|
if encoding is not None:
|
|
raise ValueError("Argument 'encoding' not supported in binary mode")
|
|
if errors is not None:
|
|
raise ValueError("Argument 'errors' not supported in binary mode")
|
|
if newline is not None:
|
|
raise ValueError("Argument 'newline' not supported in binary mode")
|
|
|
|
lz_mode = mode.replace("t", "")
|
|
binary_file = LZMAFile(filename, lz_mode, format=format, check=check,
|
|
preset=preset, filters=filters)
|
|
|
|
if "t" in mode:
|
|
encoding = io.text_encoding(encoding)
|
|
return io.TextIOWrapper(binary_file, encoding, errors, newline)
|
|
else:
|
|
return binary_file
|
|
|
|
|
|
def compress(data, format=FORMAT_XZ, check=-1, preset=None, filters=None):
|
|
"""Compress a block of data.
|
|
|
|
Refer to LZMACompressor's docstring for a description of the
|
|
optional arguments *format*, *check*, *preset* and *filters*.
|
|
|
|
For incremental compression, use an LZMACompressor instead.
|
|
"""
|
|
comp = LZMACompressor(format, check, preset, filters)
|
|
return comp.compress(data) + comp.flush()
|
|
|
|
|
|
def decompress(data, format=FORMAT_AUTO, memlimit=None, filters=None):
|
|
"""Decompress a block of data.
|
|
|
|
Refer to LZMADecompressor's docstring for a description of the
|
|
optional arguments *format*, *check* and *filters*.
|
|
|
|
For incremental decompression, use an LZMADecompressor instead.
|
|
"""
|
|
results = []
|
|
while True:
|
|
decomp = LZMADecompressor(format, memlimit, filters)
|
|
try:
|
|
res = decomp.decompress(data)
|
|
except LZMAError:
|
|
if results:
|
|
break # Leftover data is not a valid LZMA/XZ stream; ignore it.
|
|
else:
|
|
raise # Error on the first iteration; bail out.
|
|
results.append(res)
|
|
if not decomp.eof:
|
|
raise LZMAError("Compressed data ended before the "
|
|
"end-of-stream marker was reached")
|
|
data = decomp.unused_data
|
|
if not data:
|
|
break
|
|
return b"".join(results)
|