filter-branch: fail gracefully when a filter fails

A common mistake is to provide a filter which fails unwantedly. For
example, this will stop in the middle:

	git filter-branch --env-filter '
		test $GIT_COMMITTER_EMAIL = xyz &&
		export GIT_COMMITTER_EMAIL = abc' rewritten

When $GIT_COMMITTER_EMAIL is not "xyz", the test fails, and consequently
the whole filter has a non-zero exit status. However, as demonstrated
in this example, filter-branch would just stop, and the user would be
none the wiser.

Also, a failing msg-filter would not have been caught, as was the
case with one of the tests.

This patch fixes both issues, by paying attention to the exit status
of msg-filter, and by saying what failed before exiting.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
old mode 100644 (file)
new mode 100755 (executable)
index 6cf67df..d77902d
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -28,6 +28,16 @@ map()
        fi
 }
 
+# override die(): this version puts in an extra line break, so that
+# the progress is still visible
+
+die()
+{
+       echo >&2
+       echo "$*" >&2
+       exit 1
+}
+
 # When piped a commit, output a script to set the ident of either
 # "author" or "committer
 
@@ -181,23 +191,29 @@ while read commit parents; do
        export GIT_COMMIT=$commit
        git cat-file commit "$commit" >../commit
 
-       eval "$(set_ident AUTHOR <../commit)"
-       eval "$(set_ident COMMITTER <../commit)"
-       eval "$filter_env" < /dev/null
+       eval "$(set_ident AUTHOR <../commit)" ||
+               die "setting author failed for commit $commit"
+       eval "$(set_ident COMMITTER <../commit)" ||
+               die "setting committer failed for commit $commit"
+       eval "$filter_env" < /dev/null ||
+               die "env filter failed: $filter_env"
 
        if [ "$filter_tree" ]; then
                git checkout-index -f -u -a
                # files that $commit removed are now still in the working tree;
                # remove them, else they would be added again
                git ls-files -z --others | xargs -0 rm -f
-               eval "$filter_tree" < /dev/null
+               eval "$filter_tree" < /dev/null ||
+                       die "tree filter failed: $filter_tree"
+
                git diff-index -r $commit | cut -f 2- | tr '\n' '\0' | \
                        xargs -0 git update-index --add --replace --remove
                git ls-files -z --others | \
                        xargs -0 git update-index --add --replace --remove
        fi
 
-       eval "$filter_index" < /dev/null
+       eval "$filter_index" < /dev/null ||
+               die "index filter failed: $filter_index"
 
        parentstr=
        for parent in $parents; do
@@ -206,13 +222,15 @@ while read commit parents; do
                done
        done
        if [ "$filter_parent" ]; then
-               parentstr="$(echo "$parentstr" | eval "$filter_parent")"
+               parentstr="$(echo "$parentstr" | eval "$filter_parent")" ||
+                               die "parent filter failed: $filter_parent"
        fi
 
        sed -e '1,/^$/d' <../commit | \
-               eval "$filter_msg" | \
-               sh -c "$filter_commit" "git commit-tree" $(git write-tree) \
-                       $parentstr > ../map/$commit
+               eval "$filter_msg" > ../message ||
+                       die "msg filter failed: $filter_msg"
+       sh -c "$filter_commit" "git commit-tree" \
+               $(git write-tree) $parentstr < ../message > ../map/$commit
 done <../revs
 
 src_head=$(tail -n 1 ../revs | sed -e 's/ .*//')
@@ -249,7 +267,8 @@ if [ "$filter_tag_name" ]; then
                [ -f "../map/$sha1" ] || continue
                new_sha1="$(cat "../map/$sha1")"
                export GIT_COMMIT="$sha1"
-               new_ref="$(echo "$ref" | eval "$filter_tag_name")"
+               new_ref="$(echo "$ref" | eval "$filter_tag_name")" ||
+                       die "tag name filter failed: $filter_tag_name"
 
                echo "$ref -> $new_ref ($sha1 -> $new_sha1)"
 

diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index 451ac861af21fb74bbb1c52dff23c359bfb1844a..4ddd656e847e90e8f9f373e40dc41c39809d816f 100755 (executable)
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -107,13 +107,19 @@ test_expect_success 'use index-filter to move into a subdirectory' '
                  mv \$GIT_INDEX_FILE.new \$GIT_INDEX_FILE" directorymoved &&
        test -z "$(git diff HEAD directorymoved:newsubdir)"'
 
+test_expect_success 'stops when msg filter fails' '
+       ! git-filter-branch --msg-filter false nonono &&
+       rm -rf .git-rewrite &&
+       ! git rev-parse nonono
+'
+
 test_expect_success 'author information is preserved' '
        : > i &&
        git add i &&
        test_tick &&
        GIT_AUTHOR_NAME="B V Uips" git commit -m bvuips &&
        git-filter-branch --msg-filter "cat; \
-                       test \$GIT_COMMIT = $(git rev-parse master) && \
+                       test \$GIT_COMMIT != $(git rev-parse master) || \
                        echo Hallo" \
                preserved-author &&
        test 1 = $(git rev-list --author="B V Uips" preserved-author | wc -l)