1AC_DEFUN([AX_DETECT_GIT_HEAD], [
2	AC_SUBST(GIT_HEAD_ID)
3	AC_SUBST(GIT_HEAD)
4	AC_SUBST(GIT_HEAD_VERSION)
5	if test -f $srcdir/.git; then
6		gitdir=`GIT_DIR=$srcdir/.git git rev-parse --git-dir`
7		GIT_HEAD="$gitdir/index"
8		GIT_REPO="$gitdir"
9		GIT_HEAD_ID=`GIT_DIR=$GIT_REPO git describe --always`
10	elif test -f $srcdir/.git/HEAD; then
11		GIT_HEAD="$srcdir/.git/index"
12		GIT_REPO="$srcdir/.git"
13		GIT_HEAD_ID=`GIT_DIR=$GIT_REPO git describe --always`
14	elif test -f $srcdir/GIT_HEAD_ID; then
15		GIT_HEAD_ID=`cat $srcdir/GIT_HEAD_ID`
16	else
17		mysrcdir=`(cd $srcdir; pwd)`
18		head=`basename $mysrcdir | sed -e 's/.*-//'`
19		head2=`echo $head | sed -e 's/[^0-9a-f]//'`
20		head3=`echo $head2 | sed -e 's/........................................//'`
21		if test "x$head3" = "x" -a "x$head" = "x$head2"; then
22			GIT_HEAD_ID="$head"
23		else
24			GIT_HEAD_ID="UNKNOWN"
25		fi
26	fi
27	if test -z "$GIT_REPO" ; then
28		GIT_HEAD_VERSION="$GIT_HEAD_ID"
29	else
30	    GIT_HEAD_VERSION="\`GIT_DIR=$GIT_REPO git describe --always\`"
31	fi
32])
33