Changelog for hackage-security-0.5.3.0

0.5.3.0

Use flock(2)-based locking where available (compat-shim taken from cabal-install's code-base) (#207)
Improve handling of async exceptions (#187)
Detect & recover from local corruption of uncompressed index tarball (#196)
Support base-4.11

Fix client in case where server provides MD5 hashes (ignore them, use only SHA256)
Fix warnings with GHC 8

Change path handling to work on Windows (#162).
Add new MD5 hash type (#163). This is not for security (only SHA256 is used for verification) but to provide as metadata to help with other services like mirroring (e.g. HTTP & S3 use MD5 checksum headers).
Adjust reading of JSON maps to ignore unknown keys. This allows adding e.g. new hash types in future without breaking existing clients.
Fix build warnings on GHC 8

Fix for other local programs corrputing the 00-index.tar. Detect it and do a full rewrite rather than incremental append.
New JSON pretty-printer (not canonical rendering)
Round-trip tests for Canonical JSON parser and printers
Minor fix for Canonical JSON parser
Switch from cryptohash to cryptohash-sha256 to avoid new dependencies

Treat deserialization errors as verification errors (#108, #75)
Avoid Content-Length: 0 in GET requests (#103)
Fix bug in Trusted
Build tar-index incrementally (#22)
Generalize 'Repository' over the representation of downloaded remote files.
Update index incrementally by downloading delta of .tar.gz and writing only tail of local .tar file (#101). Content compression no longer used.
Take a lock on the cache directory before updating it, and no longer use atomic file ops (pointless since we now update some files incrementally)
Code refactoring/simplification.
Support for ed25519 >= 0.0.4
downloadPackage no longer takes a callback.
API for accessing the Hackage index contents changed; it should now be easier for clients to do their own incremental updates should they wish to do so.
Relies on tar >= 0.4.4
Removed obsolete option for downloading the compressed index (we now always download the compressed index)
Path module now works on Windows (#118)
Dropped support for ghc 7.2
Replaced uses of Int with Int54, to make sure canonical JSON really is canonical (#141).

Allow clients to pass in their own time for expiry verification (this is an API change hence the major version bump)
Export .Client.Formats (necessary to define new Repositories)
Start work on basic test framework