[PATCH v4] filter-branch.sh: support nearly proper tag name filtering

From

Brandon Casey <casey@nrlssc.navy.mil>

Date

Mar 26, 2008, 15:47 UTC

Message-ID

<47EA6FFD.1090805@nrlssc.navy.mil>

In-Reply-To

<7vmyolgbor.fsf@gitster.siamese.dyndns.org>

Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
---

Junio C Hamano wrote:

> Brandon Casey <casey@nrlssc.navy.mil> writes:
>> Of course, if we use ranges, we may have to worry about matching against
>> the tag body if the header gets any longer.
> 
> I do not think you have to worry if you did this:
> 
>         1,/^$/{
>                 s/object .*/object $newobject/
>                 s/type .*/type $newtype/
>                 ...
>         }

I am a sed light-weight. Thanks for teaching.

-brandon

 Documentation/git-filter-branch.txt |   14 ++++++++++----
 git-filter-branch.sh                |   18 ++++++++++++++++--
 t/t7003-filter-branch.sh            |   32 ++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 6 deletions(-)

diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt
index 2a78549..9d11b41 100644
--- a/Documentation/git-filter-branch.txt
+++ b/Documentation/git-filter-branch.txt
@@ -133,10 +133,16 @@ use "--tag-name-filter cat" to simply update the tags.  In this
 case, be very careful and make sure you have the old tags
 backed up in case the conversion has run afoul.
 +
-Note that there is currently no support for proper rewriting of
-tag objects; in layman terms, if the tag has a message or signature
-attached, the rewritten tag won't have it.  Sorry.  (It is by
-definition impossible to preserve signatures at any rate.)
+Nearly proper rewriting of tag objects is supported. If the tag has
+a message attached, a new tag object will be created with the same message,
+author, and timestamp. If the tag has a signature attached, the
+signature will be stripped. It is by definition impossible to preserve
+signatures. The reason this is "nearly" proper, is because ideally if
+the tag did not change (points to the same object, has the same name, etc.)
+it should retain any signature. That is not the case, signatures will always
+be removed, buyer beware. There is also no support for changing the
+author or timestamp (or the tag message for that matter). Tags which point
+to other tags will be rewritten to point to the underlying commit.
 
 --subdirectory-filter <directory>::
 	Only look at the history which touches the given subdirectory.
diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 22b6ed4..ee90660 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -406,8 +406,22 @@ if [ "$filter_tag_name" ]; then
 		echo "$ref -> $new_ref ($sha1 -> $new_sha1)"
 
 		if [ "$type" = "tag" ]; then
-			# Warn that we are not rewriting the tag object itself.
-			warn "unreferencing tag object $sha1t"
+			new_sha1=$(git cat-file tag "$ref" |
+				sed -n \
+				    -e "1,/^$/{
+					  s/^object .*/object $new_sha1/
+					  s/^type .*/type commit/
+					  s/^tag .*/tag $new_ref/
+					}" \
+				    -e '/^-----BEGIN PGP SIGNATURE-----/q' \
+				    -e 'p' |
+				git mktag) ||
+				die "Could not create new tag object for $ref"
+			if git cat-file tag "$ref" | \
+			   grep '^-----BEGIN PGP SIGNATURE-----' >/dev/null 2>&1
+			then
+				warn "gpg signature stripped from tag object $sha1t"
+			fi
 		fi
 
 		git update-ref "refs/tags/$new_ref" "$new_sha1" ||
diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index 6827249..1daaf54 100755
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -203,4 +203,36 @@ test_expect_success 'Subdirectory filter with disappearing trees' '
 	test $(git rev-list master | wc -l) = 3
 '
 
+test_expect_success 'Tag name filtering retains tag message' '
+	git tag -m atag T &&
+	git cat-file tag T > expect &&
+	git filter-branch -f --tag-name-filter cat &&
+	git cat-file tag T > actual &&
+	git diff expect actual
+'
+
+faux_gpg_tag='object XXXXXX
+type commit
+tag S
+tagger T A Gger <tagger@example.com> 1206026339 -0500
+
+This is a faux gpg signed tag.
+-----BEGIN PGP SIGNATURE-----
+Version: FauxGPG v0.0.0 (FAUX/Linux)
+
+gdsfoewhxu/6l06f1kxyxhKdZkrcbaiOMtkJUA9ITAc1mlamh0ooasxkH1XwMbYQ
+acmwXaWET20H0GeAGP+7vow=
+=agpO
+-----END PGP SIGNATURE-----
+'
+test_expect_success 'Tag name filtering strips gpg signature' '
+	sha1=$(git rev-parse HEAD) &&
+	sha1t=$(echo "$faux_gpg_tag" | sed -e s/XXXXXX/$sha1/ | git mktag) &&
+	git update-ref "refs/tags/S" "$sha1t" &&
+	echo "$faux_gpg_tag" | sed -e s/XXXXXX/$sha1/ | head -n 6 > expect &&
+	git filter-branch -f --tag-name-filter cat &&
+	git cat-file tag S > actual &&
+	git diff expect actual
+'
+
 test_done

-- 
1.5.4.4.481.g5075