Yet another approach to handling empty snapshots

This patch series fixes the handling of empty packed-refs snapshots (i.e., those with snapshot->buf and friends equal to NULL), partly by changing snapshot to store a pointer to the start of the post-header packed-refs content instead of header_len. It makes a couple of other improvements as well.

I'm not sure whether I like this approach better than the alternative of always setting snapshot->buf to a non-NULL value, by allocating a length-1 bit of RAM if necessary. The latter is less intrusive, though even if that approach is taken, I think patches 01, 02, and 04 from this patch series would be worthwhile improvements.

Michael

Kim Gybels (1):
packed_ref_cache: don't use mmap() for small files

Michael Haggerty (5):
struct snapshot: store start rather than header_len create_snapshot(): use xmemdupz() rather than a strbuf find_reference_location(): make function safe for empty snapshots packed_ref_iterator_begin(): make optimization more general load_contents(): don't try to mmap an empty file

 refs/packed-backend.c | 106 ++++++++++++++++++++++++++------------------------
 1 file changed, 55 insertions(+), 51 deletions(-)

2.14.2