After running into a few nil pointer errors during development, it is clear
that having this function return nil when a hash is not available is the wrong
approach. Nearly every time, this lack of availability was due to a missing
import statement for the hash. This is always a programming error.
To avoid future confusion, we now appropriately panic when the hash function is
not imported by the application. More dynamic uses of the package should call
Algorithm.Available() before calling Algorithm.Hash() to avoid this panic.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
tarsum is not actually used by the registry. Remove support for it.
Convert numerous uses in unit tests to SHA256.
Update docs to remove mentions of tarsums (which were often inaccurate).
Remove tarsum dependency.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
Previously a useful gist, this changeset polishes the original tarsum tool into
a utility that can be used to calculate content digests. Any algorithm from the
digest package is supported with additional support from tarsum.
This tool is very useful for quickly checking backend digests and verifying
correctness.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
To make the definition of supported digests more clear, we have refactored the
digest package to have a special Algorithm type. This represents the digest's
prefix and we associated various supported hash implementations through
function calls.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
The change relies on a refactor of the upstream resumable sha256/sha512 package
that opts to register implementations with the standard library. This allows
the resumable support to be detected where it matters, avoiding unnecessary and
complex code. It also ensures that consumers of the digest package don't need
to depend on the forked sha implementations.
We also get an optimization with this change. If the size of data written to a
digester is the same as the file size, we check to see if the digest has been
verified. This works if the blob is written and committed in a single request.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Vendored resumable sha256/sha512 library. Digest package new exports a
resumable variant of the Digester.
Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)
