Re: [PATCH 4/6] rebase -i: fix --committer-date-is-author-date

[Phillip Wood <phillip.wood123@gmail.com>]

Hi Elijah

On 07/04/2020 16:05, Elijah Newren wrote:
> On Tue, Apr 7, 2020 at 7:11 AM Phillip Wood <phillip.wood123@gmail.com> wrote:
>>
>> From: Phillip Wood <phillip.wood@dunelm.org.uk>
>>
>> Johanathan Nieder reported that `rebase --committer-date-is-author-date`
>> failed with the error "invalid date format: @@2592000 +0000" when the
>> backend was switched to use the sequencer [1]. This is because when we
>> read the date from the author script file is already prefixed by '@' so
>> we do not need to add one. This did not show up in our tests
>> because once match_object_header_date() fails to match because of the
>> extra '@' parse_date_basic() strips the prefix and a date with more than
>> 8 digits is parsed as a number of seconds by match_digit().
>>
>> While fixing this I also noticed that we were not setting
>> GIT_COMMITTER_DATE in the environment when forking `git merge`. This was
>> untested. The tests we did have used commits where the author date was
>> the same as the current value $GIT_COMMITTER_DATE in the environment so
>> they did not test that we were actually using the author date when
>> creating the commit.
>>
>> As we have already read GIT_AUTHOR_DATE into cmd.env_array we now use
>> that rather than re-reading the author-script file. I've moved the code
>> that handles opts->ignore date so that all the code setting the child
>> environment is together and changed it so we no longer set
>> GIT_COMMITTER_DATE twice when --ignore-date is combined with
>> --committer-date-is-author-date.
>>
>> [1] https://lore.kernel.org/git/<20200110231436.GA24315@google.com>
>>
>> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
>> ---
>>  sequencer.c                             | 68 ++++++++++---------------
>>  t/t3433-rebase-options-compatibility.sh | 29 +++++++++--
>>  2 files changed, 52 insertions(+), 45 deletions(-)
>>
>> diff --git a/sequencer.c b/sequencer.c
>> index 763ccbbc45..56f6e49289 100644
>> --- a/sequencer.c
>> +++ b/sequencer.c
>> @@ -880,17 +880,6 @@ static char *get_author(const char *message)
>>         return NULL;
>>  }
>>
>> -/* Returns a "date" string that needs to be free()'d by the caller */
>> -static char *read_author_date_or_null(void)
>> -{
>> -       char *date;
>> -
>> -       if (read_author_script(rebase_path_author_script(),
>> -                              NULL, NULL, &date, 0))
>> -               return NULL;
>> -       return date;
>> -}
>> -
>>  /* Construct a free()able author string with current time as the author date */
>>  static char *ignore_author_date(const char *author)
>>  {
>> @@ -909,16 +898,20 @@ static char *ignore_author_date(const char *author)
>>         return strbuf_detach(&new_author, NULL);
>>  }
>>
>> -static void push_dates(struct child_process *child, int change_committer_date)
>> +static const char *author_date_from_env_array(const struct argv_array *env)
>>  {
>> -       time_t now = time(NULL);
>> -       struct strbuf date = STRBUF_INIT;
>> +       int i;
>> +       const char *date;
>>
>> -       strbuf_addf(&date, "@%"PRIuMAX, (uintmax_t)now);
>> -       argv_array_pushf(&child->env_array, "GIT_AUTHOR_DATE=%s", date.buf);
>> -       if (change_committer_date)
>> -               argv_array_pushf(&child->env_array, "GIT_COMMITTER_DATE=%s", date.buf);
>> -       strbuf_release(&date);
>> +       for (i = 0; i < env->argc; i++)
>> +               if (skip_prefix(env->argv[i],
>> +                               "GIT_AUTHOR_DATE=", &date))
>> +                       return date;
> 
> Is there any risk that GIT_AUTHOR_DATE=<somedate> will appear twice in
> @child->env_array ?  If there is, should we read through the whole
> list to make sure we take the last one?

read_author_script() errors out if GIT_AUTHOR_DATE is missing or given
more than once

Best Wishes

Phillip

> 
>> +       /*
>> +        * If GIT_AUTHOR_DATE is missing we should have already errored out when
>> +        * reading the script
>> +        */
>> +       BUG("GIT_AUTHOR_DATE missing from author script");
>>  }
>>
>>  static const char staged_changes_advice[] =
>> @@ -980,31 +973,19 @@ static int run_git_commit(struct repository *r,
>>
>>         cmd.git_cmd = 1;
>>
>> -       if (opts->committer_date_is_author_date) {
>> -               int res = -1;
>> -               struct strbuf datebuf = STRBUF_INIT;
>> -               char *date = read_author_date_or_null();
>> -
>> -               if (!date)
>> -                       return -1;
>> -
>> -               strbuf_addf(&datebuf, "@%s", date);
>> -               res = setenv("GIT_COMMITTER_DATE",
>> -                            opts->ignore_date ? "" : datebuf.buf, 1);
>> -
>> -               strbuf_release(&datebuf);
>> -               free(date);
>> -
>> -               if (res)
>> -                       return -1;
>> -       }
>> -
>>         if (is_rebase_i(opts) && read_env_script(&cmd.env_array)) {
>>                 const char *gpg_opt = gpg_sign_opt_quoted(opts);
>>
>>                 return error(_(staged_changes_advice),
>>                              gpg_opt, gpg_opt);
>>         }
>> +       if (opts->committer_date_is_author_date)
>> +               argv_array_pushf(&cmd.env_array, "GIT_COMMITTER_DATE=%s",
>> +                                opts->ignore_date ?
>> +                                "" :
>> +                                author_date_from_env_array(&cmd.env_array));
>> +       if (opts->ignore_date)
>> +               argv_array_push(&cmd.env_array, "GIT_AUTHOR_DATE=");
>>
>>         argv_array_push(&cmd.args, "commit");
>>
>> @@ -1014,8 +995,6 @@ static int run_git_commit(struct repository *r,
>>                 argv_array_push(&cmd.args, "--amend");
>>         if (opts->gpg_sign)
>>                 argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
>> -       if (opts->ignore_date)
>> -               push_dates(&cmd, opts->committer_date_is_author_date);
>>         if (defmsg)
>>                 argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
>>         else if (!(flags & EDIT_MSG))
>> @@ -3615,6 +3594,13 @@ static int do_merge(struct repository *r,
>>                         ret = error(_(staged_changes_advice), gpg_opt, gpg_opt);
>>                         goto leave_merge;
>>                 }
>> +               if (opts->committer_date_is_author_date)
>> +                       argv_array_pushf(&cmd.env_array, "GIT_COMMITTER_DATE=%s",
>> +                                        opts->ignore_date ?
>> +                                        "" :
>> +                                        author_date_from_env_array(&cmd.env_array));
>> +               if (opts->ignore_date)
>> +                       argv_array_push(&cmd.env_array, "GIT_AUTHOR_DATE=");
>>
>>                 cmd.git_cmd = 1;
>>                 argv_array_push(&cmd.args, "merge");
>> @@ -3635,8 +3621,6 @@ static int do_merge(struct repository *r,
>>                 argv_array_push(&cmd.args, git_path_merge_msg(r));
>>                 if (opts->gpg_sign)
>>                         argv_array_push(&cmd.args, opts->gpg_sign);
>> -               if (opts->ignore_date)
>> -                       push_dates(&cmd, opts->committer_date_is_author_date);
>>
>>                 /* Add the tips to be merged */
>>                 for (j = to_merge; j; j = j->next)
>> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
>> index 132f577fc9..8247d01442 100755
>> --- a/t/t3433-rebase-options-compatibility.sh
>> +++ b/t/t3433-rebase-options-compatibility.sh
>> @@ -71,15 +71,15 @@ test_expect_success '--ignore-whitespace works with interactive backend' '
>>  '
>>
>>  test_expect_success '--committer-date-is-author-date works with am backend' '
>> -       git commit --amend &&
>> +       GIT_AUTHOR_DATE="@1234 +0300" git commit --amend --reset-author &&
>>         git rebase --committer-date-is-author-date HEAD^ &&
>>         git log -1 --pretty="format:%ai" >authortime &&
>>         git log -1 --pretty="format:%ci" >committertime &&
>>         test_cmp authortime committertime
>>  '
>>
>>  test_expect_success '--committer-date-is-author-date works with interactive backend' '
>> -       git commit --amend &&
>> +       GIT_AUTHOR_DATE="@1234 +0300" git commit --amend --reset-author &&
>>         git rebase -i --committer-date-is-author-date HEAD^ &&
>>         git log -1 --pretty="format:%ai" >authortime &&
>>         git log -1 --pretty="format:%ci" >committertime &&
>> @@ -88,13 +88,36 @@ test_expect_success '--committer-date-is-author-date works with interactive back
>>
>>  test_expect_success '--committer-date-is-author-date works with rebase -r' '
>>         git checkout side &&
>> -       git merge --no-ff commit3 &&
>> +       GIT_AUTHOR_DATE="@1234 +0300" git merge --no-ff commit3 &&
>>         git rebase -r --root --committer-date-is-author-date &&
>>         git log --pretty="format:%ai" >authortime &&
>>         git log --pretty="format:%ci" >committertime &&
>>         test_cmp authortime committertime
>>  '
>>
>> +test_expect_success '--committer-date-is-author-date works when forking merge' '
>> +       git checkout side &&
>> +       GIT_AUTHOR_DATE="@1234 +0300" git merge --no-ff commit3 &&
>> +       git rebase -r --root --strategy=resolve --committer-date-is-author-date &&
>> +       git log --pretty="format:%ai" >authortime &&
>> +       git log --pretty="format:%ci" >committertime &&
>> +       test_cmp authortime committertime
>> +
>> +'
>> +
>> +test_expect_success '--committer-date-is-author-date works when committing conflict resolution' '
>> +       git checkout commit2 &&
>> +       GIT_AUTHOR_DATE="@1980 +0000" git commit --amend --only --reset-author &&
>> +       git log -1 --format=%at HEAD >expect &&
>> +       test_must_fail git rebase -i --committer-date-is-author-date \
>> +               --onto HEAD^^ HEAD^ &&
>> +       echo resolved > foo &&
>> +       git add foo &&
>> +       git rebase --continue &&
>> +       git log -1 --format=%ct HEAD >actual &&
>> +       test_cmp expect actual
>> +'
>> +
>>  # Checking for +0000 in author time is enough since default
>>  # timezone is UTC, but the timezone used while committing
>>  # sets to +0530.
>> --
>> 2.26.0
>>