Attribution

hfsplus hfsplus in.hfs setattr <file> <attr-key> <attr-value>

• sets an extended attribute on file with the given key and value

dmg build in.hfs out.dmg <sentinel>

• arrange for the one (or two) blocks that the sentinel spans to be BZ_RAW
• writes out AttributionResource in the Name key of the plst resource

dmg attribute in.dmg out.dmg <sentinel> <replacement> N.b. attribute shouldn't parse the DMG, it should operate on bytestream

• read attribution resource
• update bytes in BZ_RAW block in place
• update <blkx> checksum
• update data fork checksum (compressed)
• update master checksum (uncompressed)

Testing

The gold standard is to create two HFS filesystems, both with the same xattr but with distinct values, and build attributable DMGs with the same sentinel (a prefix of the distinct values, say).

See the *_reference.t tests for Cram tests that generate such HFS and DMG files.

See the other tests for tests that exercise dmg build and dmg attribute.

Future

It would be nice to add a command to convert an existing DMG file to an attributable one, like:

dmg attributable <in.dmg> <out.dmg> <sentinel>

• arrange for the one (or two) blocks that the sentinel spans to be BZ_RAW
• writes out AttributionResource in the Name key of the plst resource