[PATCH v3 1/2] filter-branch: stop special-casing $filter_subdir argument

[Thomas Rast <trast@student.ethz.ch>]

Handling $filter_subdir in the usual way requires a separate case at
every use, because the variable is empty when unused.

Furthermore, the case for --subdirectory-filter supplies its own --,
so the user cannot provide one himself, so the following was
impossible:

  git filter-branch --subdirectory-filter subdir -- --all -- subdir/file

To keep the argument handling sane, we filter $@ to contain only the
non-revision arguments, and store all revisions in $ref_args.  The
$ref_args are easy to handle since only the SHA1s are needed; the
actual branch names have already been stored in $tempdir/heads at this
point.

An extra separating -- is only required if the user did not provide
any non-revision arguments, as the latter disambiguate the
$filter_subdir following after them (or fail earlier because they are
ambiguous themselves).

Thanks to Johannes Sixt for suggesting this solution.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
---

Johannes Sixt wrote:
> When the shell expands $variable (outside quotes), it does not apply
> quotes anymore, but only word-splits using $IFS. In your code, the words
> would contain literal single-quotes, and paths with spaces would still be
> split into words.

If there's a good reason for these weird rules, I'm still missing
it...

But your suggestion works very nicely.

 git-filter-branch.sh |   21 ++++++++++++++-------
 1 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index a480d6f..da23b99 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -257,15 +257,23 @@ git read-tree || die "Could not seed the index"
 # map old->new commit ids for rewriting parents
 mkdir ../map || die "Could not create map/ directory"
 
+dashdash=
+test -z "$(git rev-parse --no-revs "$@")" && dashdash=--
+ref_args=$(git rev-parse --revs-only "$@")
+
 case "$filter_subdir" in
 "")
-	git rev-list --reverse --topo-order --default HEAD \
-		--parents --simplify-merges "$@"
+	eval set -- "$(git rev-parse --sq --no-revs "$@")"
 	;;
 *)
-	git rev-list --reverse --topo-order --default HEAD \
-		--parents --simplify-merges "$@" -- "$filter_subdir"
-esac > ../revs || die "Could not get the commits"
+	eval set -- "$(git rev-parse --sq --no-revs "$@")" \
+	    $dashdash "$filter_subdir"
+	;;
+esac
+
+git rev-list --reverse --topo-order --default HEAD \
+	--parents --simplify-merges $ref_args "$@" \
+	> ../revs || die "Could not get the commits"
 commits=$(wc -l <../revs | tr -d " ")
 
 test $commits -eq 0 && die "Found nothing to rewrite"
@@ -356,8 +364,7 @@ then
 	do
 		sha1=$(git rev-parse "$ref"^0)
 		test -f "$workdir"/../map/$sha1 && continue
-		ancestor=$(git rev-list --simplify-merges -1 \
-				$ref -- "$filter_subdir")
+		ancestor=$(git rev-list --simplify-merges -1 "$ref" "$@")
 		test "$ancestor" && echo $(map $ancestor) >> "$workdir"/../map/$sha1
 	done < "$tempdir"/heads
 fi
-- 
1.6.5.1.161.g3b9c0