Subject: Re: [GSoC][PATCH v2 3/6] rebase -i: support --committer-date-is-author-date

From: Phillip Wood <[email-masked]>
Date: Tue, 13 Aug 2019 11:38:57 +0100

Hi Rohit

This is looking good, I think it is almost there now

On 12/08/2019 20:42, 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 <[email-masked]>
> ---
>   Documentation/git-rebase.txt            |  8 +++-
>   builtin/rebase.c                        | 20 ++++++---
>   sequencer.c                             | 57 ++++++++++++++++++++++++-
>   sequencer.h                             |  1 +
>   t/t3422-rebase-incompatible-options.sh  |  1 -
>   t/t3433-rebase-options-compatibility.sh | 19 +++++++++
>   6 files changed, 96 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 28e5e08a83..697ce8e6ff 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -383,8 +383,12 @@ default is `--no-fork-point`, otherwise the default is `--fork-point`.
>   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
> +	This flag is passed to 'git am' to change the author date
>   	of the rebased commits (see linkgit:git-am[1]).
>   +
>   See also INCOMPATIBLE OPTIONS below.
> @@ -522,7 +526,6 @@ INCOMPATIBLE OPTIONS
>   
>   The following options:
>   
> - * --committer-date-is-author-date
>    * --ignore-date
>    * --whitespace
>    * -C
> @@ -548,6 +551,7 @@ 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 ab1bbb78ee..b1039f8db0 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;
>   
> @@ -533,6 +536,9 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
>   		warning(_("--[no-]rebase-cousins has no effect without "
>   			  "--rebase-merges"));
>   
> +	if (opts.committer_date_is_author_date)
> +		opts.flags |= REBASE_FORCE;
> +
>   	return !!run_rebase_interactive(&opts, command);
>   }
>   
> @@ -981,6 +987,8 @@ 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);
> @@ -1424,9 +1432,9 @@ 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"),
> @@ -1697,10 +1705,12 @@ 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..fbc0ed0cad 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();

You must always check the return value of functions that might return 
NULL. In this case we should return an error as you do in try_to 
_commit() later

> +
> +		strbuf_addf(&datebuf, "@%s", date);

GNU printf() will add something like '(null)' to the buffer if you pass 
a NULL pointer so I don't think we can be sure that this will not 
increase the length of the buffer if date is NULL. An explicit check 
above would be much clearer as well rather than checking len later. What 
happens if you don't add the '@' at the beginning? (I'm don't know much 
about git's date handling)

> +		free(date);
> +
> +		date = strbuf_detach(&datebuf, &len);
> +
> +		if (len > 1)
> +			res = setenv("GIT_COMMITTER_DATE", date, 1);
> +
> +		free(date);
> +
> +		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"));

We return an error if we cannot get the date - this is exactly what we 
should be doing above. It is also great to see a single version of this 
being used whether or not we are amending.

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

I think we should use %s.* and ident.date_end to be sure we getting what 
we want. Your version is OK if the author is formatted correctly but I'm 
uneasy about relying on that when we can get the verified end from ident.

Best Wishes

Phillip

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