git rebase -i: add static check for commands and SHA-1

Check before the start of the rebasing if the commands exists, and for
the commands expecting a SHA-1, check if the SHA-1 is present and
corresponds to a commit. In case of error, print the error, stop git
rebase and prompt the user to fix with 'git rebase --edit-todo' or to
abort.

This allows to avoid doing half of a rebase before finding an error
and giving back what's left of the todo list to the user and prompt
him to fix when it might be too late for him to do so (he might have
to abort and restart the rebase).

Signed-off-by: Galan Rémi <remi.galan-alfonso@ensimag.grenoble-inp.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 116 insertions, 0 deletions

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index c26a200a6c..dcc3401b5a 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -846,6 +846,71 @@ add_exec_commands () {
 	mv "$1.new" "$1"
 }
 
+# Check if the SHA-1 passed as an argument is a
+# correct one, if not then print $2 in "$todo".badsha
+# $1: the SHA-1 to test
+# $2: the line to display if incorrect SHA-1
+check_commit_sha () {
+	badsha=0
+	if test -z $1
+	then
+		badsha=1
+	else
+		sha1_verif="$(git rev-parse --verify --quiet $1^{commit})"
+		if test -z $sha1_verif
+		then
+			badsha=1
+		fi
+	fi
+
+	if test $badsha -ne 0
+	then
+		warn "Warning: the SHA-1 is missing or isn't" \
+			"a commit in the following line:"
+		warn " - $2"
+		warn
+	fi
+
+	return $badsha
+}
+
+# prints the bad commits and bad commands
+# from the todolist in stdin
+check_bad_cmd_and_sha () {
+	retval=0
+	git stripspace --strip-comments |
+	(
+		while read -r line
+		do
+			IFS=' '
+			set -- $line
+			command=$1
+			sha1=$2
+
+			case $command in
+			''|noop|x|"exec")
+				# Doesn't expect a SHA-1
+				;;
+			pick|p|drop|d|reword|r|edit|e|squash|s|fixup|f)
+				if ! check_commit_sha $sha1 "$line"
+				then
+					retval=1
+				fi
+				;;
+			*)
+				warn "Warning: the command isn't recognized" \
+					"in the following line:"
+				warn " - $line"
+				warn
+				retval=1
+				;;
+			esac
+		done
+
+		return $retval
+	)
+}
+
 # Print the list of the SHA-1 of the commits
 # from stdin to stdout
 todo_list_to_sha_list () {
@@ -887,6 +952,8 @@ get_missing_commit_check_level () {
 
 # Check if the user dropped some commits by mistake
 # Behaviour determined by rebase.missingCommitsCheck.
+# Check if there is an unrecognized command or a
+# bad SHA-1 in a command.
 check_todo_list () {
 	raise_error=f
 
@@ -935,6 +1002,11 @@ check_todo_list () {
 		;;
 	esac
 
+	if ! check_bad_cmd_and_sha <"$todo"
+	then
+		raise_error=t
+	fi
+
 	if test $raise_error = t
 	then
 		# Checkout before the first commit of the
diff --git a/t/lib-rebase.sh b/t/lib-rebase.sh
index fdbc9007d0..9a96e1566d 100644
--- a/t/lib-rebase.sh
+++ b/t/lib-rebase.sh
@@ -54,6 +54,11 @@ set_fake_editor () {
 			echo '# comment' >> "$1";;
 		">")
 			echo >> "$1";;
+		bad)
+			action="badcmd";;
+		fakesha)
+			echo "$action XXXXXXX False commit" >> "$1"
+			action=pick;;
 		*)
 			sed -n "${line}s/^pick/$action/p" < "$1".tmp >> "$1"
 			action=pick;;
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index cfa741018d..ebdab4b95d 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1186,4 +1186,43 @@ test_expect_success 'rebase -i respects rebase.missingCommitsCheck = error' '
 	test B = $(git cat-file commit HEAD^ | sed -ne \$p)
 '
 
+cat >expect <<EOF
+Warning: the command isn't recognized in the following line:
+ - badcmd $(git rev-list --oneline -1 master~1)
+
+You can fix this with 'git rebase --edit-todo'.
+Or you can abort the rebase with 'git rebase --abort'.
+EOF
+
+test_expect_success 'static check of bad command' '
+	rebase_setup_and_clean bad-cmd &&
+	set_fake_editor &&
+	test_must_fail env FAKE_LINES="1 2 3 bad 4 5" \
+		git rebase -i --root 2>actual &&
+	test_cmp expect actual &&
+	FAKE_LINES="1 2 3 drop 4 5" git rebase --edit-todo &&
+	git rebase --continue &&
+	test E = $(git cat-file commit HEAD | sed -ne \$p) &&
+	test C = $(git cat-file commit HEAD^ | sed -ne \$p)
+'
+
+cat >expect <<EOF
+Warning: the SHA-1 is missing or isn't a commit in the following line:
+ - edit XXXXXXX False commit
+
+You can fix this with 'git rebase --edit-todo'.
+Or you can abort the rebase with 'git rebase --abort'.
+EOF
+
+test_expect_success 'static check of bad SHA-1' '
+	rebase_setup_and_clean bad-sha &&
+	set_fake_editor &&
+	test_must_fail env FAKE_LINES="1 2 edit fakesha 3 4 5 #" \
+		git rebase -i --root 2>actual &&
+	test_cmp expect actual &&
+	FAKE_LINES="1 2 4 5 6" git rebase --edit-todo &&
+	git rebase --continue &&
+	test E = $(git cat-file commit HEAD | sed -ne \$p)
+'
+
 test_done