filter-branch: handle "disappearing tree" case correctly in subdir filter

The subdirectory filter had a bug to notice that the commit in question
did not have anything in the path-limited part of the tree.  $commit:$path
does not name an empty tree when $path does not appear in $commit.

This should fix it.  The additional test in t7003 is originally from Kevin
Ballard but with fixups.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 49e13f0bb1ed2bcb6e85455f24dffa912927d67a..010353ad82881886b9739cc5f8de595acc9273ef 100755 (executable)
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -252,7 +252,16 @@ while read commit parents; do
                git read-tree -i -m $commit
                ;;
        *)
-               git read-tree -i -m $commit:"$filter_subdir"
+               # The commit may not have the subdirectory at all
+               err=$(git read-tree -i -m $commit:"$filter_subdir" 2>&1) || {
+                       if ! git rev-parse --verify $commit:"$filter_subdir" 2>/dev/null
+                       then
+                               rm -f "$GIT_INDEX_FILE"
+                       else
+                               echo >&2 "$err"
+                               false
+                       fi
+               }
        esac || die "Could not initialize the index"
 
        GIT_COMMIT=$commit

diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index 868babc4b2350526192a8df53f6cbec3f81c644e..6e14bf1c7f0991bbaab217e8a08bae0cacfe1ab1 100755 (executable)
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -179,4 +179,28 @@ test_expect_success 'Name needing quotes' '
 
 '
 
+test_expect_success 'Subdirectory filter with disappearing trees' '
+       git reset --hard &&
+       git checkout master &&
+
+       mkdir foo &&
+       touch foo/bar &&
+       git add foo &&
+       test_tick &&
+       git commit -m "Adding foo" &&
+
+       git rm -r foo &&
+       test_tick &&
+       git commit -m "Removing foo" &&
+
+       mkdir foo &&
+       touch foo/bar &&
+       git add foo &&
+       test_tick &&
+       git commit -m "Re-adding foo" &&
+
+       git filter-branch -f --subdirectory-filter foo &&
+       test $(git rev-list master | wc -l) = 3
+'
+
 test_done