[PATCH v2 3/9] svn-fe: allow svnadmin instead of svnrdump in remote-svn-alpha

[Dmitry Ivankov <divanorama@gmail.com>]

svnrdump dump and svnadmin dump share a dump format. Their dump
streams representation may be different but they should have the
same effect on a dump consumer. One more difference is svnrdump being
able to dump via any svn remote protocol while svnadmin needs access
to the repository filesystem and also can't produce subdirectory dumps.
But svnrdump is a newer tool and may be unavailable on some systems.

Try to use svnadmin dump for file:// repository urls if there is no
svnrdump in the PATH. First of all this is to be used in tests, where
the repository is indeed local most of the time. Also require svnlook
utility as a lightweight option to get the youngest repository revision.

Signed-off-by: Dmitry Ivankov <divanorama@gmail.com>
---
 contrib/svn-fe/git-remote-svn-alpha |   31 ++++++++++++++++++++++++++++++-
 1 files changed, 30 insertions(+), 1 deletions(-)

diff --git a/contrib/svn-fe/git-remote-svn-alpha b/contrib/svn-fe/git-remote-svn-alpha
index 2eac7d4..ca9d431 100755
--- a/contrib/svn-fe/git-remote-svn-alpha
+++ b/contrib/svn-fe/git-remote-svn-alpha
@@ -28,9 +28,38 @@ svnrdump_wrap () {
 	fi
 }
 
+try_svnrdump () {
+	command -v svnrdump >/dev/null &&
+	echo svnrdump_wrap ||
+	true
+}
+
+svnadmin_wrap () {
+	path=${1##file://} &&
+	test "z$path" != "z$1" &&
+	latest=$(svnlook youngest "$path") &&
+	future=$(( $latest + 1 )) &&
+	asked=${2#-r} &&
+	asked=${asked%:*} &&
+	test "$asked" -eq "$future" ||
+	svnadmin dump --incremental --deltas --quiet "$path" "$2"
+}
+
+try_svnadmin () {
+	command -v svnadmin >/dev/null &&
+	command -v svnlook >/dev/null &&
+	echo svnadmin_wrap ||
+	true
+}
+
+SVNDUMP=""
+SVNDUMP=${SVNDUMP:-`try_svnrdump`}
+SVNDUMP=${SVNDUMP:-`try_svnadmin`}
+test -n "$SVNDUMP" || die "neither svnrdump nor svnadmin & svnlook was found"
+
 do_import () {
 	revs=$1 url=$2
-	(svnrdump_wrap "$url" -r"$revs" | svn-fe) 3<&0 || die "FAILURE"
+	(eval "$SVNDUMP \"$url\" -r\"$revs\"" |	svn-fe) 3<&0 || die "FAILURE"
 	exec 1>&-
 }
 
-- 
1.7.3.4