bpo-34472: Add data descriptor signature to zipfile (GH-8871)
This makes streamed zips compatible with MacOS Archive Utility and
other applications.
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index 89df90b..4a6b40e 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -159,6 +159,8 @@
_CD64_DIRECTORY_SIZE = 8
_CD64_OFFSET_START_CENTDIR = 9
+_DD_SIGNATURE = 0x08074b50
+
_EXTRA_FIELD_STRUCT = struct.Struct('<HH')
def _strip_extra(extra, xids):
@@ -1118,8 +1120,8 @@
# Write updated header info
if self._zinfo.flag_bits & 0x08:
# Write CRC and file sizes after the file data
- fmt = '<LQQ' if self._zip64 else '<LLL'
- self._fileobj.write(struct.pack(fmt, self._zinfo.CRC,
+ fmt = '<LLQQ' if self._zip64 else '<LLLL'
+ self._fileobj.write(struct.pack(fmt, _DD_SIGNATURE, self._zinfo.CRC,
self._zinfo.compress_size, self._zinfo.file_size))
self._zipfile.start_dir = self._fileobj.tell()
else:
diff --git a/Misc/ACKS b/Misc/ACKS
index a29ff60..96563f6 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1468,6 +1468,7 @@
Jerry Seutter
Pete Sevander
Denis Severson
+Silas Sewell
Ian Seyer
Dmitry Shachnev
Anish Shah
diff --git a/Misc/NEWS.d/next/Library/2018-08-23-09-25-08.bpo-34472.cGyYrO.rst b/Misc/NEWS.d/next/Library/2018-08-23-09-25-08.bpo-34472.cGyYrO.rst
new file mode 100644
index 0000000..208ec0b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-08-23-09-25-08.bpo-34472.cGyYrO.rst
@@ -0,0 +1,3 @@
+Improved compatibility for streamed files in :mod:`zipfile`. Previously an
+optional signature was not being written and certain ZIP applications were
+not supported. Patch by Silas Sewell.