Deterministic zip files

[ws333]

Hi,

does the zip.js library support generation of deterministic zip files? I.e. the zipped files of identical files have the same SHA checksums.

Like the '-X' / '--no-extra' option for zip.

From the zip man page:

-X
--no-extra
Do not save extra file attributes (Extended Attributes on OS/2,
uid/gid and file times on Unix). The zip format uses extra
fields to include additional information for each entry. Some
extra fields are specific to particular systems while others are
applicable to all systems. Normally when zip reads entries from
an existing archive, it reads the extra fields it knows, strips
the rest, and adds the extra fields applicable to that system.
With -X, zip strips all old fields and only includes the Unicode
and Zip64 extra fields (currently these two extra fields cannot
be disabled).
Negating this option, -X-, includes all the default extra
fields, but also copies over any unrecognized extra fields.

A post on SO about this https://stackoverflow.com/a/72272606/12019249

[gildas-lormeau]

if I read correctly, the equivalent of -X in zip.js is to set the option extendedTimestamp to false.

EDIT: You should also set useCompressionStream to false to make sure the compressed data is always the same (see #554) across different environments.

[ws333]

Yes, that worked! Thanks for the quick reply ✨

[gildas-lormeau]

You're welcome!