diff options
| -rw-r--r-- | Doc/library/gzip.rst | 14 | ||||
| -rw-r--r-- | Lib/gzip.py | 8 |
2 files changed, 16 insertions, 6 deletions
diff --git a/Doc/library/gzip.rst b/Doc/library/gzip.rst index 0ae23d2..82f10b9 100644 --- a/Doc/library/gzip.rst +++ b/Doc/library/gzip.rst @@ -70,6 +70,17 @@ The module defines the following items: including iteration and the :keyword:`with` statement. Only the :meth:`truncate` method isn't implemented. + :class:`GzipFile` also provides the following method: + + .. method:: peek([n]) + + Read *n* uncompressed bytes without advancing the file position. + At most one single read on the compressed stream is done to satisfy + the call. The number of bytes returned may be more or less than + requested. + + .. versionadded:: 3.2 + .. versionchanged:: 3.1 Support for the :keyword:`with` statement was added. @@ -79,9 +90,6 @@ The module defines the following items: .. 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 58e866b..7c3fd51 100644 --- a/Lib/gzip.py +++ b/Lib/gzip.py @@ -342,16 +342,18 @@ class GzipFile(io.BufferedIOBase): def peek(self, n): if self.mode != READ: import errno - raise IOError(errno.EBADF, "read() on write-only GzipFile object") + raise IOError(errno.EBADF, "peek() on write-only GzipFile object") - # Do not return ridiculously small buffers + # Do not return ridiculously small buffers, for one common idiom + # is to call peek(1) and expect more bytes in return. 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)) + # 1024 is the same buffering heuristic used in read() + self._read(max(n, 1024)) except EOFError: pass offset = self.offset - self.extrastart |