srctree=.
if test $# -gt 0; then
	srctree=$1
	shift
fi
if test $# -gt 0 -o ! -d "$srctree"; then
	usage
fi

scm_version()
{
	cd "$srctree"

	# Check for git and a git repo.
	if test -z "$(git rev-parse --show-cdup 2>/dev/null)" &&
	   head=`git rev-parse --verify --short HEAD 2>/dev/null`; then

		# If we are at a tagged commit (like "v2.6.30-rc6"), we ignore
		# it, because this version is defined in the top level Makefile.
		if [ -z "`git describe --exact-match 2>/dev/null`" ]; then
			# If we are past a tagged commit (like
			# "v2.6.30-rc5-302-g72357d5"), we pretty print it.
			if atag="`git describe 2>/dev/null`"; then
				echo "$atag" | awk -F- '{printf("-%05d-%s", $(NF-1),$(NF))}'

			# If we don't have a tag at all we print -g{commitish}.
			else
				printf '%s%s' -g $head
			fi
		fi

		# Is this git on svn?
		if git config --get svn-remote.svn.url >/dev/null; then
			printf -- '-svn%s' "`git svn find-rev $head`"
		fi

		# Check for uncommitted changes
		if git diff-index --name-only HEAD | grep -qv "^scripts/package"; then
			printf '%s' -dirty
		fi

		# All done with git
		return
	fi

	# Check for mercurial and a mercurial repo.
	if test -d .hg && hgid=`hg id 2>/dev/null`; then
		# Do we have an tagged version?  If so, latesttagdistance == 1
		if [ "`hg log -r . --template '{latesttagdistance}'`" == "1" ]; then
			id=`hg log -r . --template '{latesttag}'`
			printf '%s%s' -hg "$id"
		else
			tag=`printf '%s' "$hgid" | cut -d' ' -f2`
			if [ -z "$tag" -o "$tag" = tip ]; then
				id=`printf '%s' "$hgid" | sed 's/[+ ].*//'`
				printf '%s%s' -hg "$id"
			fi
		fi

		# Are there uncommitted changes?
		# These are represented by + after the changeset id.
		case "$hgid" in
			*+|*+\ *) printf '%s' -dirty ;;
		esac

		# All done with mercurial
		return
	fi

	# Check for svn and a svn repo.
	if rev=`LANG= LC_ALL= LC_MESSAGES=C svn info 2>/dev/null | grep '^Last Changed Rev'`; then
		rev=`echo $rev | awk '{print $NF}'`
		printf -- '-svn%s' "$rev"

		# All done with svn
		return
	fi
}

# full scm version string
res="$res$(scm_version)"

echo "$res"