| """Interface to the libbzip2 compression library. |
| |
| This module provides a file interface, classes for incremental |
| (de)compression, and functions for one-shot (de)compression. |
| """ |
| |
| __all__ = ["BZ2File", "BZ2Compressor", "BZ2Decompressor", |
| "open", "compress", "decompress"] |
| |
| __author__ = "Nadeem Vawda <nadeem.vawda@gmail.com>" |
| |
| from builtins import open as _builtin_open |
| import io |
| import os |
| import warnings |
| import _compression |
| from threading import RLock |
| |
| from _bz2 import BZ2Compressor, BZ2Decompressor |
| |
| |
| _MODE_CLOSED = 0 |
| _MODE_READ = 1 |
| # Value 2 no longer used |
| _MODE_WRITE = 3 |
| |
| _sentinel = object() |
| |
| |
| class BZ2File(_compression.BaseStream): |
| |
| """A file object providing transparent bzip2 (de)compression. |
| |
| A BZ2File can act as a wrapper for an existing file object, or refer |
| directly to a named file on disk. |
| |
| Note that BZ2File provides a *binary* file interface - data read is |
| returned as bytes, and data to be written should be given as bytes. |
| """ |
| |
| def __init__(self, filename, mode="r", buffering=_sentinel, compresslevel=9): |
| """Open a bzip2-compressed file. |
| |
| If filename is a str, bytes, or PathLike object, it gives the |
| name of the file to be opened. Otherwise, it should be a file |
| object, which will be used to read or write the compressed data. |
| |
| 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'. |
| |
| buffering is ignored since Python 3.0. Its use is deprecated. |
| |
| If mode is 'w', 'x' or 'a', compresslevel can be a number between 1 |
| and 9 specifying the level of compression: 1 produces the least |
| compression, and 9 (default) produces the most compression. |
| |
| If mode is 'r', the input file may be the concatenation of |
| multiple compressed streams. |
| """ |
| # This lock must be recursive, so that BufferedIOBase's |
| # writelines() does not deadlock. |
| self._lock = RLock() |
| self._fp = None |
| self._closefp = False |
| self._mode = _MODE_CLOSED |
| |
| if buffering is not _sentinel: |
| warnings.warn("Use of 'buffering' argument is deprecated and ignored " |
| "since Python 3.0.", |
| DeprecationWarning, |
| stacklevel=2) |
| |
| if not (1 <= compresslevel <= 9): |
| raise ValueError("compresslevel must be between 1 and 9") |
| |
| if mode in ("", "r", "rb"): |
| mode = "rb" |
| mode_code = _MODE_READ |
| elif mode in ("w", "wb"): |
| mode = "wb" |
| mode_code = _MODE_WRITE |
| self._compressor = BZ2Compressor(compresslevel) |
| elif mode in ("x", "xb"): |
| mode = "xb" |
| mode_code = _MODE_WRITE |
| self._compressor = BZ2Compressor(compresslevel) |
| elif mode in ("a", "ab"): |
| mode = "ab" |
| mode_code = _MODE_WRITE |
| self._compressor = BZ2Compressor(compresslevel) |
| else: |
| raise ValueError("Invalid mode: %r" % (mode,)) |
| |
| if isinstance(filename, (str, bytes, os.PathLike)): |
| self._fp = _builtin_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, |
| BZ2Decompressor, trailing_error=OSError) |
| self._buffer = io.BufferedReader(raw) |
| else: |
| self._pos = 0 |
| |
| 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. |
| """ |
| with self._lock: |
| if self._mode == _MODE_CLOSED: |
| return |
| try: |
| if self._mode == _MODE_READ: |
| self._buffer.close() |
| 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 |
| self._buffer = None |
| |
| @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, n=0): |
| """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. |
| """ |
| with self._lock: |
| self._check_can_read() |
| # Relies on the undocumented fact that BufferedReader.peek() |
| # always returns at least one byte (except at EOF), independent |
| # of the value of n |
| return self._buffer.peek(n) |
| |
| 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. |
| """ |
| with self._lock: |
| 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. |
| """ |
| with self._lock: |
| self._check_can_read() |
| if size < 0: |
| size = io.DEFAULT_BUFFER_SIZE |
| return self._buffer.read1(size) |
| |
| def readinto(self, b): |
| """Read bytes into b. |
| |
| Returns the number of bytes read (0 for EOF). |
| """ |
| with self._lock: |
| self._check_can_read() |
| return self._buffer.readinto(b) |
| |
| 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. |
| """ |
| if not isinstance(size, int): |
| if not hasattr(size, "__index__"): |
| raise TypeError("Integer argument expected") |
| size = size.__index__() |
| with self._lock: |
| self._check_can_read() |
| return self._buffer.readline(size) |
| |
| def readlines(self, size=-1): |
| """Read a list of lines of uncompressed bytes from the file. |
| |
| size can be specified to control the number of lines read: no |
| further lines will be read once the total size of the lines read |
| so far equals or exceeds size. |
| """ |
| if not isinstance(size, int): |
| if not hasattr(size, "__index__"): |
| raise TypeError("Integer argument expected") |
| size = size.__index__() |
| with self._lock: |
| self._check_can_read() |
| return self._buffer.readlines(size) |
| |
| def write(self, data): |
| """Write a byte string to the file. |
| |
| Returns the number of uncompressed bytes written, which is |
| always len(data). Note that due to buffering, the file on disk |
| may not reflect the data written until close() is called. |
| """ |
| with self._lock: |
| self._check_can_write() |
| compressed = self._compressor.compress(data) |
| self._fp.write(compressed) |
| self._pos += len(data) |
| return len(data) |
| |
| def writelines(self, seq): |
| """Write a sequence of byte strings to the file. |
| |
| Returns the number of uncompressed bytes written. |
| seq can be any iterable yielding byte strings. |
| |
| Line separators are not added between the written byte strings. |
| """ |
| with self._lock: |
| return _compression.BaseStream.writelines(self, seq) |
| |
| 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. 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. |
| """ |
| with self._lock: |
| self._check_can_seek() |
| return self._buffer.seek(offset, whence) |
| |
| def tell(self): |
| """Return the current file position.""" |
| with self._lock: |
| self._check_not_closed() |
| if self._mode == _MODE_READ: |
| return self._buffer.tell() |
| return self._pos |
| |
| |
| def open(filename, mode="rb", compresslevel=9, |
| encoding=None, errors=None, newline=None): |
| """Open a bzip2-compressed file in binary or text mode. |
| |
| The filename argument can be an actual filename (a str, bytes, or |
| PathLike object), or an existing file object to read from or write |
| to. |
| |
| The mode argument can be "r", "rb", "w", "wb", "x", "xb", "a" or |
| "ab" for binary mode, or "rt", "wt", "xt" or "at" for text mode. |
| The default mode is "rb", and the default compresslevel is 9. |
| |
| For binary mode, this function is equivalent to the BZ2File |
| constructor: BZ2File(filename, mode, compresslevel). In this case, |
| the encoding, errors and newline arguments must not be provided. |
| |
| For text mode, a BZ2File 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") |
| |
| bz_mode = mode.replace("t", "") |
| binary_file = BZ2File(filename, bz_mode, compresslevel=compresslevel) |
| |
| if "t" in mode: |
| return io.TextIOWrapper(binary_file, encoding, errors, newline) |
| else: |
| return binary_file |
| |
| |
| def compress(data, compresslevel=9): |
| """Compress a block of data. |
| |
| compresslevel, if given, must be a number between 1 and 9. |
| |
| For incremental compression, use a BZ2Compressor object instead. |
| """ |
| comp = BZ2Compressor(compresslevel) |
| return comp.compress(data) + comp.flush() |
| |
| |
| def decompress(data): |
| """Decompress a block of data. |
| |
| For incremental decompression, use a BZ2Decompressor object instead. |
| """ |
| results = [] |
| while data: |
| decomp = BZ2Decompressor() |
| try: |
| res = decomp.decompress(data) |
| except OSError: |
| if results: |
| break # Leftover data is not a valid bzip2 stream; ignore it. |
| else: |
| raise # Error on the first iteration; bail out. |
| results.append(res) |
| if not decomp.eof: |
| raise ValueError("Compressed data ended before the " |
| "end-of-stream marker was reached") |
| data = decomp.unused_data |
| return b"".join(results) |
