With Zip64 write support enabled by default, it's important that we
only store the extra data when we need to. This commit ensures that
the Zip64 extra data is included for an entry if its size is over
4GB, or if we don't know how big it will be at the point of writing
the local header data.
This commit also removes the need for the Zip64Placeholder extra
data field. Now we just use the Zip64 field itself and ensure it's
filled in correctly.
When loading extra fields from both the central directory and local headers,
unknown fields were not merged correctly. They were being appended, which
means that we end up with the two versions stuck together - in some
cases duplicating the field completely.
This broke all kinds of things (like calculating the size of a local
header) in subtle ways.
This commit fixes this by implementing a new `Unknown` extra field type,
and making sure that when reading local and central extra fields they
are stored and preserved correctly. We cannot assume the unknown fields
use the same data in the local and central headers.
Fixes#505.
This commit adds the capability of creating archives larger than
4GB via zip64 extensions. It also fixes bugs reading archives of
this size (specifically, the 64-bit offset of the local file
header was not being read from the central directory entry).
To maximize compatibility, zip64 extensions are used only when
required. Unfortunately, at the time we write a local file header,
we don't know the size of the file and thus whether a Zip64
Extended Information Extra Field will be required. Therefore
this commit writes a 'placeholder' extra field to reserve space
for the zip64 entry, which will be written if necessary when
we update the local entry with the final sizes and CRC. I use
the signature "\x99\x99" for this field, following the example
of DotNetZip which does the same.
This commit also adds a rake task, zip64_full_test, which
fully tests zip64 by actually creating and verifying a 4GB zip
file. Please note, however, that this test requires UnZip
version 6.00 or newer, which may not be supplied by your OS.
This test doesn't run along with the main unit tests because
it takes a few minutes to complete.
Robert Haines
taichi
Takumasa Ochi
Pavel Lobashov
Vít Ondruch
Pavel.Lobashov
Henry Yang
Alexander Simonov
Sam Rawlins
Jeremy Stanley