/usr/lib/python3.7/bz2.py is in libpython3.7-stdlib 3.7.0~b3-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 | """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
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=None, 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. 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 None:
warnings.warn("Use of 'buffering' argument is deprecated",
DeprecationWarning)
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)
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