• brian m. carlson's avatar
    Add structure representing hash algorithm · f50e766b
    brian m. carlson authored
    Since in the future we want to support an additional hash algorithm, add
    a structure that represents a hash algorithm and all the data that must
    go along with it.  Add a constant to allow easy enumeration of hash
    algorithms.  Implement function typedefs to create an abstract API that
    can be used by any hash algorithm, and wrappers for the existing SHA1
    functions that conform to this API.
    
    Expose a value for hex size as well as binary size.  While one will
    always be twice the other, the two values are both used extremely
    commonly throughout the codebase and providing both leads to improved
    readability.
    
    Don't include an entry in the hash algorithm structure for the null
    object ID.  As this value is all zeros, any suitably sized all-zero
    object ID can be used, and there's no need to store a given one on a
    per-hash basis.
    
    The current hash function transition plan envisions a time when we will
    accept input from the user that might be in SHA-1 or in the NewHash
    format.  Since we cannot know which the user has provided, add a
    constant representing the unknown algorithm to allow us to indicate that
    we must look the correct value up.  Provide dummy API functions that die
    in this case.
    
    Finally, include git-compat-util.h in hash.h so that the required types
    are available.  This aids people using automated tools their editors.
    Signed-off-by: brian m. carlson's avatarbrian m. carlson <sandals@crustytoothpaste.net>
    Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
    f50e766b
hash.h 1.95 KB