Issue #9962: GzipFile now has the peek() method.
diff --git a/Doc/library/gzip.rst b/Doc/library/gzip.rst
index dc04ba0..0ae23d2 100644
--- a/Doc/library/gzip.rst
+++ b/Doc/library/gzip.rst
@@ -25,10 +25,10 @@
.. class:: GzipFile(filename=None, mode=None, compresslevel=9, fileobj=None, mtime=None)
- Constructor for the :class:`GzipFile` class, which simulates most of the methods
- of a :term:`file object`, with the exception of the :meth:`readinto` and
- :meth:`truncate` methods. At least one of *fileobj* and *filename* must be
- given a non-trivial value.
+ Constructor for the :class:`GzipFile` class, which simulates most of the
+ methods of a :term:`file object`, with the exception of the :meth:`truncate`
+ method. At least one of *fileobj* and *filename* must be given a non-trivial
+ value.
The new class instance is based on *fileobj*, which can be a regular file, a
:class:`StringIO` object, or any other object which simulates a file. It
@@ -66,8 +66,9 @@
writing as *fileobj*, and retrieve the resulting memory buffer using the
:class:`io.BytesIO` object's :meth:`~io.BytesIO.getvalue` method.
- :class:`GzipFile` supports the whole :class:`io.BufferedIOBase` interface,
- including iteration and the :keyword:`with` statement.
+ :class:`GzipFile` supports the :class:`io.BufferedIOBase` interface,
+ including iteration and the :keyword:`with` statement. Only the
+ :meth:`truncate` method isn't implemented.
.. versionchanged:: 3.1
Support for the :keyword:`with` statement was added.
@@ -78,6 +79,9 @@
.. versionchanged:: 3.2
Support for unseekable files was added.
+ .. versionchanged:: 3.2
+ The :meth:`peek` method was implemented.
+
.. function:: open(filename, mode='rb', compresslevel=9)
diff --git a/Lib/gzip.py b/Lib/gzip.py
index 3edc839..58e866b 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -204,7 +204,10 @@
return self.name
def __repr__(self):
- s = repr(self.fileobj)
+ fileobj = self.fileobj
+ if isinstance(fileobj, _PaddedFile):
+ fileobj = fileobj.file
+ s = repr(fileobj)
return '<gzip ' + s[1:-1] + ' ' + hex(id(self)) + '>'
def _init_write(self, filename):
@@ -336,6 +339,26 @@
self.offset += size
return chunk
+ def peek(self, n):
+ if self.mode != READ:
+ import errno
+ raise IOError(errno.EBADF, "read() on write-only GzipFile object")
+
+ # Do not return ridiculously small buffers
+ if n < 100:
+ n = 100
+ if self.extrasize == 0:
+ if self.fileobj is None:
+ return b''
+ try:
+ self._read(max(self.max_read_chunk, n))
+ except EOFError:
+ pass
+ offset = self.offset - self.extrastart
+ remaining = self.extrasize
+ assert remaining == len(self.extrabuf) - offset
+ return self.extrabuf[offset:offset + n]
+
def _unread(self, buf):
self.extrasize = len(buf) + self.extrasize
self.offset -= len(buf)
diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
index e49fe00..8e493b5 100644
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -286,6 +286,28 @@
with gzip.GzipFile(fileobj=buf, mode="rb") as f:
self.assertEqual(f.read(), uncompressed)
+ def test_peek(self):
+ uncompressed = data1 * 200
+ with gzip.GzipFile(self.filename, "wb") as f:
+ f.write(uncompressed)
+
+ def sizes():
+ while True:
+ for n in range(5, 50, 10):
+ yield n
+
+ with gzip.GzipFile(self.filename, "rb") as f:
+ f.max_read_chunk = 33
+ nread = 0
+ for n in sizes():
+ s = f.peek(n)
+ if s == b'':
+ break
+ self.assertEqual(f.read(len(s)), s)
+ nread += len(s)
+ self.assertEqual(f.read(100), b'')
+ self.assertEqual(nread, len(uncompressed))
+
# Testing compress/decompress shortcut functions
def test_compress(self):
diff --git a/Misc/NEWS b/Misc/NEWS
index f774926..0daba08 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -76,6 +76,8 @@
Library
-------
+- Issue #9962: GzipFile now has the peek() method.
+
- Issue #9090: When a socket with a timeout fails with EWOULDBLOCK or EAGAIN,
retry the select() loop instead of bailing out. This is because select()
can incorrectly report a socket as ready for reading (for example, if it