"brian m. carlson" <sandals@xxxxxxxxxxxxxxxxxxxx> writes: > We have a a variety of uses of GIT_HASH_SHA1 littered throughout our > code. Some of these really mean to represent specifically SHA-1, but > some actually represent the original hash algorithm used in Git which is > implied by older formats and protocols which do not contain hash > information. For instance, the bundle v1 and v2 formats do not contain > hash algorithm information, and thus SHA-1 is implied by the use of > these formats. Does that mean use of _ORIGINAL is a sign that these places should keep using SHA-1 and should not change? I am having a hard time guessing/assessing the value of having _ORIGINAL that is a synonym for _SHA1; with redirection, it pretends as if the underlying value can be updated from SHA-1 to SHA-256 (and that is the very intention behind GIT_HASH_DEFAULT symbol that gives us a level of indirection), but it is hard to imagine we would ever want to change what _ORIGINAL means, as that word talks about a historical fact that will never change over time. > Add a constant for documentary purposes which indicates this value. It > will always be the same as SHA-1, since this is an essential part of > these formats, but its use indicates this particular reason and not any > other reason why SHA-1 might be used. I am not sure what this means. If we use GIT_HASH_SHA1 in such places explicitly (as opposed to GIT_HASH_DEFAULT), isn't it a sign enough that with different versions of Git, that particular code path should keep using SHA-1 no matter what the default is? > Signed-off-by: brian m. carlson <sandals@xxxxxxxxxxxxxxxxxxxx> > --- > hash.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/hash.h b/hash.h > index 0d3d85e04c..0e14cade4e 100644 > --- a/hash.h > +++ b/hash.h > @@ -176,6 +176,8 @@ static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *s > #define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1) > /* Default hash algorithm if unspecified. */ > #define GIT_HASH_DEFAULT GIT_HASH_SHA1 > +/* Original hash algorithm. Implied for older data formats which don't specify. */ > +#define GIT_HASH_ORIGINAL GIT_HASH_SHA1 > > /* "sha1", big-endian */ > #define GIT_SHA1_FORMAT_ID 0x73686131
