"git_path()" returns a static pathname pointer into the git directory
using a printf-like format specifier.
"head_ref()" works like "for_each_ref()", except for just the HEAD.
This patch adds code to read a hash out of a specified file under
{GIT_DIR}/refs/, and to write such files atomically and optionally with an
compare and lock.
Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
