Re: [PATCH v3 3/6] rebase -i: support --committer-date-is-author-date

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

Hi Rohit

One thing that struck we was that we should support this with rebase -r 
which means setting GIT_COMMITTER_DATE when we fork 'git merge'. I've 
got a couple of other comments below

On 20/08/2019 04:45, Rohit Ashiwal wrote:
> rebase am already has this flag to "lie" about the committer date
> by changing it to the author date. Let's add the same for
> interactive machinery.
> 
> Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
> ---
>   Documentation/git-rebase.txt            | 10 +++--
>   builtin/rebase.c                        | 17 +++++---
>   sequencer.c                             | 57 ++++++++++++++++++++++++-
>   sequencer.h                             |  1 +
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 19 +++++++++
>   6 files changed, 94 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 873eb5768c..e7c0eac18c 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -386,9 +386,13 @@ unchanged for the sake of a three-way merge.
>   See also INCOMPATIBLE OPTIONS below.
>   
>   --committer-date-is-author-date::
> +	Instead of recording the time the rebased commits are
> +	created as the committer date, reuse the author date
> +	as the committer date. This implies --force-rebase.
> +
>   --ignore-date::
> -	These flags are passed to 'git am' to easily change the dates
> -	of the rebased commits (see linkgit:git-am[1]).
> +	This flag is passed to 'git am' to change the author date
> +	of each rebased commit (see linkgit:git-am[1]).
>   +
>   See also INCOMPATIBLE OPTIONS below.
>   
> @@ -525,7 +529,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
>    * -C
> @@ -551,6 +554,7 @@ In addition, the following pairs of options are incompatible:
>    * --preserve-merges and --signoff
>    * --preserve-merges and --rebase-merges
>    * --preserve-merges and --ignore-whitespace
> + * --preserve-merges and --committer-date-is-author-date
>    * --rebase-merges and --ignore-whitespace
>    * --rebase-merges and --strategy
>    * --rebase-merges and --strategy-option
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index f8a618d54c..656bc7d7e9 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -82,6 +82,7 @@ struct rebase_options {
>   	int ignore_whitespace;
>   	char *gpg_sign_opt;
>   	int autostash;
> +	int committer_date_is_author_date;
>   	char *cmd;
>   	int allow_empty_message;
>   	int rebase_merges, rebase_cousins;
> @@ -114,6 +115,8 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   	replay.allow_empty_message = opts->allow_empty_message;
>   	replay.verbose = opts->flags & REBASE_VERBOSE;
>   	replay.reschedule_failed_exec = opts->reschedule_failed_exec;
> +	replay.committer_date_is_author_date =
> +					opts->committer_date_is_author_date;
>   	replay.gpg_sign = xstrdup_or_null(opts->gpg_sign_opt);
>   	replay.strategy = opts->strategy;
>   
> @@ -976,6 +979,8 @@ static int run_am(struct rebase_options *opts)
>   
>   	if (opts->ignore_whitespace)
>   		argv_array_push(&am.args, "--ignore-whitespace");
> +	if (opts->committer_date_is_author_date)
> +		argv_array_push(&opts->git_am_opts, "--committer-date-is-author-date");
>   	if (opts->action && !strcmp("continue", opts->action)) {
>   		argv_array_push(&am.args, "--resolved");
>   		argv_array_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
> @@ -1419,9 +1424,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   			PARSE_OPT_NOARG, NULL, REBASE_DIFFSTAT },
>   		OPT_BOOL(0, "signoff", &options.signoff,
>   			 N_("add a Signed-off-by: line to each commit")),
> -		OPT_PASSTHRU_ARGV(0, "committer-date-is-author-date",
> -				  &options.git_am_opts, NULL,
> -				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
> +		OPT_BOOL(0, "committer-date-is-author-date",
> +			 &options.committer_date_is_author_date,
> +			 N_("make committer date match author date")),
>   		OPT_PASSTHRU_ARGV(0, "ignore-date", &options.git_am_opts, NULL,
>   				  N_("passed to 'git am'"), PARSE_OPT_NOARG),
>   		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
> @@ -1692,10 +1697,12 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		    state_dir_base, cmd_live_rebase, buf.buf);
>   	}
>   
> +	if (options.committer_date_is_author_date)
> +		options.flags |= REBASE_FORCE;
> +
>   	for (i = 0; i < options.git_am_opts.argc; i++) {
>   		const char *option = options.git_am_opts.argv[i], *p;
> -		if (!strcmp(option, "--committer-date-is-author-date") ||
> -		    !strcmp(option, "--ignore-date") ||
> +		if (!strcmp(option, "--ignore-date") ||
>   		    !strcmp(option, "--whitespace=fix") ||
>   		    !strcmp(option, "--whitespace=strip"))
>   			options.flags |= REBASE_FORCE;
> diff --git a/sequencer.c b/sequencer.c
> index 30d77c2682..29b67bc1ae 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -147,6 +147,7 @@ static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
>    * command-line.
>    */
>   static GIT_PATH_FUNC(rebase_path_gpg_sign_opt, "rebase-merge/gpg_sign_opt")
> +static GIT_PATH_FUNC(rebase_path_cdate_is_adate, "rebase-merge/cdate_is_adate")
>   static GIT_PATH_FUNC(rebase_path_orig_head, "rebase-merge/orig-head")
>   static GIT_PATH_FUNC(rebase_path_verbose, "rebase-merge/verbose")
>   static GIT_PATH_FUNC(rebase_path_quiet, "rebase-merge/quiet")
> @@ -879,6 +880,17 @@ 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;
> +}
> +
>   /* Read author-script and return an ident line (author <email> timestamp) */
>   static const char *read_author_ident(struct strbuf *buf)
>   {
> @@ -964,6 +976,25 @@ static int run_git_commit(struct repository *r,
>   {
>   	struct child_process cmd = CHILD_PROCESS_INIT;
>   
> +	if (opts->committer_date_is_author_date) {
> +		size_t len;
> +		int res = -1;
> +		struct strbuf datebuf = STRBUF_INIT;
> +		char *date = read_author_date_or_null();
> +
> +		if (!date)
> +			return -1;

It is good to this this new error checking

> +
> +		strbuf_addf(&datebuf, "@%s", date);
> +		free(date);
> +
> +		date = strbuf_detach(&datebuf, &len);
> +		res = setenv("GIT_COMMITTER_DATE", date, 1);
> +		free(date);

This could be simplified slightly by doing
	res = setenv("GIT_COMMITTER_DATE", datebuf.buf. 1);
	strbuf_release(&datebuf);

> +
> +		if (res)
> +			return -1;
> +	}
>   	if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
>   		struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
>   		const char *author = NULL;
> @@ -1400,7 +1431,6 @@ static int try_to_commit(struct repository *r,
>   
>   	if (parse_head(r, &current_head))
>   		return -1;
> -
>   	if (flags & AMEND_MSG) {
>   		const char *exclude_gpgsig[] = { "gpgsig", NULL };
>   		const char *out_enc = get_commit_output_encoding();
> @@ -1427,6 +1457,21 @@ static int try_to_commit(struct repository *r,
>   		commit_list_insert(current_head, &parents);
>   	}
>   
> +	if (opts->committer_date_is_author_date) {
> +		int len = strlen(author);
> +		struct ident_split ident;
> +		struct strbuf date = STRBUF_INIT;
> +
> +		split_ident_line(&ident, author, len);
> +
> +		if (!ident.date_begin)
> +			return error(_("corrupted author without date information"));

I had to read the source of split_ident_line() to check this was safe, I 
think it is better to use the return value to check for errors  - a 
quick greps shows that this is what all the other callers do.

> +
> +		strbuf_addf(&date, "@%s", ident.date_begin);

I still think this will pass any junk after a corrupted timezone, it 
would be better to do

	strbuf_addf(&date, "@%.*s %.*s", ident.date_begin, ident.data_end - 
ident.date_begin, ident.tz_begin, ident.tz_end - ident.tz_begin);

> +		setenv("GIT_COMMITTER_DATE", date.buf, 1);

The code above (in run_git_commit()) checks the return value of setenv() 
and returns an error if it failed should this be doing the same?

Best Wishes

Phillip

> +		strbuf_release(&date);
> +	}
> +
>   	if (write_index_as_tree(&tree, r->index, r->index_file, 0, NULL)) {
>   		res = error(_("git write-tree failed to write a tree"));
>   		goto out;
> @@ -2542,6 +2587,11 @@ static int read_populate_opts(struct replay_opts *opts)
>   			opts->signoff = 1;
>   		}
>   
> +		if (file_exists(rebase_path_cdate_is_adate())) {
> +			opts->allow_ff = 0;
> +			opts->committer_date_is_author_date = 1;
> +		}
> +
>   		if (file_exists(rebase_path_reschedule_failed_exec()))
>   			opts->reschedule_failed_exec = 1;
>   
> @@ -2624,6 +2674,8 @@ int write_basic_state(struct replay_opts *opts, const char *head_name,
>   		write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
>   	if (opts->signoff)
>   		write_file(rebase_path_signoff(), "--signoff\n");
> +	if (opts->committer_date_is_author_date)
> +		write_file(rebase_path_cdate_is_adate(), "%s", "");
>   	if (opts->reschedule_failed_exec)
>   		write_file(rebase_path_reschedule_failed_exec(), "%s", "");
>   
> @@ -3821,7 +3873,8 @@ static int pick_commits(struct repository *r,
>   	setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
>   	if (opts->allow_ff)
>   		assert(!(opts->signoff || opts->no_commit ||
> -				opts->record_origin || opts->edit));
> +				opts->record_origin || opts->edit ||
> +				opts->committer_date_is_author_date));
>   	if (read_and_refresh_cache(r, opts))
>   		return -1;
>   
> diff --git a/sequencer.h b/sequencer.h
> index 6704acbb9c..e3881e9275 100644
> --- a/sequencer.h
> +++ b/sequencer.h
> @@ -43,6 +43,7 @@ struct replay_opts {
>   	int verbose;
>   	int quiet;
>   	int reschedule_failed_exec;
> +	int committer_date_is_author_date;
>   
>   	int mainline;
>   
> diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
> index 4342f79eea..7402f7e3da 100755
> --- a/t/t3422-rebase-incompatible-options.sh
> +++ b/t/t3422-rebase-incompatible-options.sh
> @@ -61,7 +61,6 @@ test_rebase_am_only () {
>   }
>   
>   test_rebase_am_only --whitespace=fix
> -test_rebase_am_only --committer-date-is-author-date
>   test_rebase_am_only -C4
>   
>   test_expect_success REBASE_P '--preserve-merges incompatible with --signoff' '
> diff --git a/t/t3433-rebase-options-compatibility.sh b/t/t3433-rebase-options-compatibility.sh
> index 2e16e00a9d..b2419a2b75 100755
> --- a/t/t3433-rebase-options-compatibility.sh
> +++ b/t/t3433-rebase-options-compatibility.sh
> @@ -7,6 +7,9 @@ test_description='tests to ensure compatibility between am and interactive backe
>   
>   . ./test-lib.sh
>   
> +GIT_AUTHOR_DATE="1999-04-02T08:03:20+05:30"
> +export GIT_AUTHOR_DATE
> +
>   # This is a special case in which both am and interactive backends
>   # provide the same output. It was done intentionally because
>   # both the backends fall short of optimal behaviour.
> @@ -62,4 +65,20 @@ test_expect_success '--ignore-whitespace works with interactive backend' '
>   	test_cmp expect file
>   '
>   
> +test_expect_success '--committer-date-is-author-date works with am backend' '
> +	git commit --amend &&
> +	git rebase --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
> +test_expect_success '--committer-date-is-author-date works with interactive backend' '
> +	git commit --amend &&
> +	git rebase -i --committer-date-is-author-date HEAD^ &&
> +	git show HEAD --pretty="format:%ai" >authortime &&
> +	git show HEAD --pretty="format:%ci" >committertime &&
> +	test_cmp authortime committertime
> +'
> +
>   test_done
>