python-checkins at python
Aug 4, 2012, 6:39 AM
Post #1 of 1
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cpython: #15546: Fix BZ2File.read1()'s handling of pathological input data.
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http://hg.python.org/cpython/rev/cdf27a213bd2
changeset: 78409:cdf27a213bd2
user: Nadeem Vawda <nadeem.vawda [at] gmail>
date: Sat Aug 04 15:29:28 2012 +0200
summary:
#15546: Fix BZ2File.read1()'s handling of pathological input data.
files:
Lib/bz2.py | 47 +++++++++++++++++++++++------------------
1 files changed, 26 insertions(+), 21 deletions(-)
diff --git a/Lib/bz2.py b/Lib/bz2.py
--- a/Lib/bz2.py
+++ b/Lib/bz2.py
@@ -174,29 +174,31 @@
# Fill the readahead buffer if it is empty. Returns False on EOF.
def _fill_buffer(self):
- if self._buffer:
- return True
+ # Depending on the input data, our call to the decompressor may not
+ # return any data. In this case, try again after reading another block.
+ while True:
+ if self._buffer:
+ return True
- if self._decompressor.unused_data:
- rawblock = self._decompressor.unused_data
- else:
- rawblock = self._fp.read(_BUFFER_SIZE)
+ if self._decompressor.unused_data:
+ rawblock = self._decompressor.unused_data
+ else:
+ rawblock = self._fp.read(_BUFFER_SIZE)
- if not rawblock:
+ if not rawblock:
+ if self._decompressor.eof:
+ self._mode = _MODE_READ_EOF
+ self._size = self._pos
+ return False
+ else:
+ raise EOFError("Compressed file ended before the "
+ "end-of-stream marker was reached")
+
+ # Continue to next stream.
if self._decompressor.eof:
- self._mode = _MODE_READ_EOF
- self._size = self._pos
- return False
- else:
- raise EOFError("Compressed file ended before the "
- "end-of-stream marker was reached")
+ self._decompressor = BZ2Decompressor()
- # Continue to next stream.
- if self._decompressor.eof:
- self._decompressor = BZ2Decompressor()
-
- self._buffer = self._decompressor.decompress(rawblock)
- return True
+ self._buffer = self._decompressor.decompress(rawblock)
# Read data until EOF.
# If return_data is false, consume the data without returning it.
@@ -256,11 +258,14 @@
return self._read_block(size)
def read1(self, size=-1):
- """Read up to size uncompressed bytes with at most one read
- from the underlying stream.
+ """Read up to size uncompressed bytes, while trying to avoid
+ making multiple reads from the underlying stream.
Returns b'' if the file is at EOF.
"""
+ # Usually, read1() calls _fp.read() at most once. However, sometimes
+ # this does not give enough data for the decompressor to make progress.
+ # In this case we make multiple reads, to avoid returning b"".
with self._lock:
self._check_can_read()
if (size == 0 or self._mode == _MODE_READ_EOF or
--
Repository URL: http://hg.python.org/cpython
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