[PATCH 3/3] validate_headref: use get_oid_hex for detached HEADs

If a candidate HEAD isn't a symref, we check that it contains a viable sha1. But in a post-sha1 world, we should be checking whether it has any plausible object-id.

We can do that by switching to get_oid_hex().

Note that both before and after this patch, we only check for a plausible object id at the start of the file, and then call that good enough. We ignore any content _after_ the hex, so a string like:

  0123456789012345678901234567890123456789 foo

is accepted. Though we do put extra bytes like this into some pseudorefs (e.g., FETCH_HEAD), we don't typically do so with HEAD. We could tighten this up by using parse_oid_hex(), like:

  if (!parse_oid_hex(buffer, &oid, &end) &&
      *end++ == '\n' && *end == '\0')
          return 0;

But we're probably better to remain on the loose side. We're just checking here for a plausible-looking repository directory, so heuristics are acceptable (if we really want to be meticulous, we should use the actual ref code to parse HEAD).

Signed-off-by: Jeff King <peff@peff.net>
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 path.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)