| | """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 _compression |
| |
|
| | from _bz2 import BZ2Compressor, BZ2Decompressor |
| |
|
| |
|
| | _MODE_CLOSED = 0 |
| | _MODE_READ = 1 |
| | |
| | _MODE_WRITE = 3 |
| |
|
| |
|
| | 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", *, 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'. |
| | |
| | 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. |
| | """ |
| | self._fp = None |
| | self._closefp = False |
| | self._mode = _MODE_CLOSED |
| |
|
| | 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. |
| | """ |
| | 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. |
| | """ |
| | self._check_can_read() |
| | |
| | |
| | |
| | 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. |
| | """ |
| | 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 readinto(self, b): |
| | """Read bytes into b. |
| | |
| | Returns the number of bytes read (0 for EOF). |
| | """ |
| | 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__() |
| | 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__() |
| | 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 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: |
| | |
| | data = memoryview(data) |
| | length = data.nbytes |
| |
|
| | compressed = self._compressor.compress(data) |
| | self._fp.write(compressed) |
| | self._pos += length |
| | return length |
| |
|
| | 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. |
| | """ |
| | 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. |
| | """ |
| | 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", 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: |
| | encoding = io.text_encoding(encoding) |
| | 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 |
| | else: |
| | raise |
| | 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) |
| |
|
