rebase -i: fix short SHA-1 collision

The 'todo' sheet for interactive rebase shows abbreviated SHA-1's and
then performs its operations upon those shortened values. This can lead
to an abort if the SHA-1 of a reworded or edited commit is no longer
unique within the abbreviated SHA-1 space and a subsequent SHA-1 in the
todo list has the same abbreviated value.

For example:

  edit f00dfad first
  pick badbeef second

If, after editing, the new SHA-1 of "first" also has prefix badbeef,
then the subsequent 'pick badbeef second' will fail since badbeef is no
longer a unique SHA-1 abbreviation:

  error: short SHA1 badbeef is ambiguous.
  fatal: Needed a single revision
  Invalid commit name: badbeef

Fix this problem by expanding the SHA-1's in the todo list before
performing the operations.

[es: also collapse & expand SHA-1's for --edit-todo; respect
core.commentchar in transform_todo_ids(); compose commit message]

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 83d6d46..b97a1d0 100644 (file)
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -689,6 +689,32 @@ skip_unnecessary_picks () {
        die "Could not skip unnecessary pick commands"
 }
 
+transform_todo_ids () {
+       while read -r command rest
+       do
+               case "$command" in
+               "$comment_char"* | exec)
+                       # Be careful for oddball commands like 'exec'
+                       # that do not have a SHA-1 at the beginning of $rest.
+                       ;;
+               *)
+                       sha1=$(git rev-parse --verify --quiet "$@" ${rest%% *}) &&
+                       rest="$sha1 ${rest#* }"
+                       ;;
+               esac
+               printf '%s\n' "$command${rest:+ }$rest"
+       done <"$todo" >"$todo.new" &&
+       mv -f "$todo.new" "$todo"
+}
+
+expand_todo_ids() {
+       transform_todo_ids
+}
+
+collapse_todo_ids() {
+       transform_todo_ids --short=7
+}
+
 # Rearrange the todo list that has both "pick sha1 msg" and
 # "pick sha1 fixup!/squash! msg" appears in it so that the latter
 # comes immediately after the former, and change "pick" to
@@ -841,6 +867,7 @@ skip)
 edit-todo)
        git stripspace --strip-comments <"$todo" >"$todo".new
        mv -f "$todo".new "$todo"
+       collapse_todo_ids
        append_todo_help
        git stripspace --comment-lines >>"$todo" <<\EOF
 
@@ -852,6 +879,7 @@ EOF
 
        git_sequence_editor "$todo" ||
                die "Could not execute editor"
+       expand_todo_ids
 
        exit
        ;;
@@ -1008,6 +1036,8 @@ git_sequence_editor "$todo" ||
 has_action "$todo" ||
        die_abort "Nothing to do"
 
+expand_todo_ids
+
 test -d "$rewritten" || test -n "$force_rebase" || skip_unnecessary_picks
 
 GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $onto_name"

diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 64a02a0..6cdc2ea 100755 (executable)
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1049,7 +1049,7 @@ test_expect_success 'short SHA-1 setup' '
        )
 '
 
-test_expect_failure 'short SHA-1 collide' '
+test_expect_success 'short SHA-1 collide' '
        test_when_finished "reset_rebase && git checkout master" &&
        git checkout collide &&
        (