tree b05bc7afb0dfbfdfa8789c737dbedf83fbd9c169
parent 8bfabfa9cbabb5e97af0c9f824d1c47da5028024
author Michael Hoisie <hoisie@google.com> 1670014548 -0800
committer Copybara-Service <copybara-worker@google.com> 1670014587 -0800

Support zip files where EOCD's offset to central dir is -1

When zip files contain more than 2**16 entries, the regular EOCD is
not sufficient to describe the number of files in the archive, and
a Zip64 EOCD needs to be written.

When a Zip64 EOCD is written, some zip libraries write -1 for many
of the fields in the regular EOCD, including the offset to central dir:

From APPNOTE.TXT §4.4.1.4
  If one of the fields in the end of central directory
  record is too small to hold required data, the field SHOULD be
  set to -1 (0xFFFF or 0xFFFFFFFF) and the ZIP64 format record
  SHOULD be created.

Previously FileMap assumed that the regular EOCD contained a valid
offset to central dir field. This broke recently when an experimental
Android SDK had more than 64k entries in the zip file and -1 for the
offset to the central dir.

Add support for reading the offset to the central from the Zip64 EOCD.
Also add a test case that generates a problematic zip file.

PiperOrigin-RevId: 492538213