rebase -x: sanity check command

If the user gives an empty argument to --exec then git creates a todo
list that it cannot parse. The rebase starts to run before erroring out
with

  error: missing arguments for exec
  error: invalid line 2: exec
  You can fix this with 'git rebase --edit-todo' and then run 'git rebase --continue'.
  Or you can abort the rebase with 'git rebase --abort'.

Instead check for empty commands before starting the rebase.

Also check that the command does not contain any newlines as the
todo-list format is unable to cope with multiline commands. Note that
this changes the behavior, before this change one could do

git rebase --exec='echo one
exec echo two'

and it would insert two exec lines in the todo list, now it will error
out.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 7a440e08d8..c98f64eb2d 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -147,6 +147,25 @@ test_expect_success 'rebase -i with the exec command checks tree cleanness' '
 	git rebase --continue
 '
 
+test_expect_success 'rebase -x with empty command fails' '
+	test_when_finished "git rebase --abort ||:" &&
+	test_must_fail git rebase -x "" @ 2>actual &&
+	test_write_lines "error: empty exec command" >expected &&
+	test_i18ncmp expected actual &&
+	test_must_fail git rebase -x " " @ 2>actual &&
+	test_i18ncmp expected actual
+'
+
+LF='
+'
+test_expect_success 'rebase -x with newline in command fails' '
+	test_when_finished "git rebase --abort ||:" &&
+	test_must_fail git rebase -x "a${LF}b" @ 2>actual &&
+	test_write_lines "error: exec commands cannot contain newlines" \
+			 >expected &&
+	test_i18ncmp expected actual
+'
+
 test_expect_success 'rebase -i with exec of inexistent command' '
 	git checkout master &&
 	test_when_finished "git rebase --abort" &&