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"""
Utility functions for decoding response bodies.
"""
from __future__ import absolute_import
from io import BytesIO
import gzip
import zlib
ENCODINGS = {"identity", "gzip", "deflate"}
def decode(e, content):
if not isinstance(content, bytes):
return None
encoding_map = {
"identity": identity,
"gzip": decode_gzip,
"deflate": decode_deflate,
}
if e not in encoding_map:
return None
return encoding_map[e](content)
def encode(e, content):
if not isinstance(content, bytes):
return None
encoding_map = {
"identity": identity,
"gzip": encode_gzip,
"deflate": encode_deflate,
}
if e not in encoding_map:
return None
return encoding_map[e](content)
def identity(content):
"""
Returns content unchanged. Identity is the default value of
Accept-Encoding headers.
"""
return content
def decode_gzip(content):
gfile = gzip.GzipFile(fileobj=BytesIO(content))
try:
return gfile.read()
except (IOError, EOFError):
return None
def encode_gzip(content):
s = BytesIO()
gf = gzip.GzipFile(fileobj=s, mode='wb')
gf.write(content)
gf.close()
return s.getvalue()
def decode_deflate(content):
"""
Returns decompressed data for DEFLATE. Some servers may respond with
compressed data without a zlib header or checksum. An undocumented
feature of zlib permits the lenient decompression of data missing both
values.
http://bugs.python.org/issue5784
"""
try:
try:
return zlib.decompress(content)
except zlib.error:
return zlib.decompress(content, -15)
except zlib.error:
return None
def encode_deflate(content):
"""
Returns compressed content, always including zlib header and checksum.
"""
return zlib.compress(content)
__all__ = ["ENCODINGS", "encode", "decode"]
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