[PATCH v3] [GSOC]trailer: pass arg as positional parameter

From: ZheNing Hu <adlternative@gmail.com>

Original implementation of `trailer.<token>.command` use `strbuf_replace` to replace $ARG in command with the <value> of the trailer, but it have a problem: `strbuf_replace` replace the $ARG only once, If the user's trailer command have used more than one $ARG, the remaining replacement will fail.

If directly modify the implementation of the original `trailer.<token>.command`, The user’s previous `'$ARG'` in trailer command will not be replaced. So now add new config "trailer.<token>.cmd", pass trailer's value as positional parameter 1 to the user's command, the user can use $1 as trailer's value, to implement original variable replacement.

If the user has these two configuration: "trailer.<token>.cmd" and "trailer.<token>.command", "cmd" will execute and "command" will not executed.

Original `trailer.<token>.command` can still be used until git completely abandoned it.

Signed-off-by: ZheNing Hu <adlternative@gmail.com>
---
    [GSOC]trailer: pass arg as positional parameter
    
    In https://lore.kernel.org/git/xmqqv99i4ck2.fsf@gitster.g/ Junio and
    Christian talked about the problem of using strbuf_replace() to replace
    $ARG.
    
    Now pass trailer value as $1 to the trailer command with another
    trailer.<token>.cmd config.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-913%2Fadlternative%2Ftrailer-pass-ARG-env-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-913/adlternative/trailer-pass-ARG-env-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/913

Range-diff vs v2:

 1:  185356d6fc90 ! 1:  b268ecd7b395 [GSOC]trailer: pass arg as positional parameter
     @@ Metadata
       ## Commit message ##
          [GSOC]trailer: pass arg as positional parameter
      
     -    In the original implementation of `trailer.<token>.command`,
     -    use `strbuf_replace` to replace $ARG in the <value> of the
     -    trailer, but it have a problem: `strbuf_replace` replace the
     -    $ARG in command only once, If the user's trailer command have
     -    used more than one $ARG, error will occur.
     +    Original implementation of `trailer.<token>.command` use
     +    `strbuf_replace` to replace $ARG in command with the <value>
     +    of the trailer, but it have a problem: `strbuf_replace`
     +    replace the $ARG only once, If the user's trailer command
     +    have used more than one $ARG, the remaining replacement will
     +    fail.
      
          If directly modify the implementation of the original
          `trailer.<token>.command`, The user’s previous `'$ARG'` in
     -    trailer command will not be replaced. So now add new
     -    config "trailer.<token>.cmd", pass trailer's value as
     -    positional parameter 1 to the user's command, users can
     -    use $1 as trailer's value, to implement original variable
     -    replacement.
     +    trailer command will not be replaced. So now add new config
     +    "trailer.<token>.cmd", pass trailer's value as positional
     +    parameter 1 to the user's command, the user can use $1 as
     +    trailer's value, to implement original variable replacement.
     +
     +    If the user has these two configuration: "trailer.<token>.cmd"
     +    and "trailer.<token>.command", "cmd" will execute and "command"
     +    will not executed.
      
          Original `trailer.<token>.command` can still be used until git
          completely abandoned it.
     @@ Documentation/git-interpret-trailers.txt: also be executed for each of these arg
      +trailer.<token>.cmd::
      +	Similar to 'trailer.<token>.command'. But the difference is that
      +	`$1` is used in the command to replace the value of the trailer
     -+	instead of the original `$ARG`, which means that we can quote the
     ++	instead of the original `$ARG`, which means that we can pass the
      +	trailer value multiple times in the command.
     -+	E.g. `trailer.sign.cmd="test -n \"$1\" && echo \"$1\" || true "`
     ++	E.g. `git config trailer.sign.cmd "test -n \"$1\" && echo \"$1\" || true "`.
     ++	If the user has these two configuration: "trailer.<token>.cmd"
     ++	and "trailer.<token>.command", "cmd" will be executed and "command"
     ++	will not be executed.
      +
       EXAMPLES
       --------
     @@ t/t7513-interpret-trailers.sh: test_expect_success 'setup a commit' '
       	git commit -m "Add file a.txt"
       '
       
     -+test_expect_success 'with cmd using $1' '
     ++test_expect_success 'with cmd and $1' '
      +	test_when_finished "git config --unset trailer.fix.cmd" &&
      +	git config trailer.fix.ifExists "replace" &&
      +	git config trailer.fix.cmd "test -n \"\$1\" && git log -1 --oneline --format=\"%h (%s)\" \
     @@ t/t7513-interpret-trailers.sh: test_expect_success 'setup a commit' '
      +		<complex_message >actual2 &&
      +	test_cmp expected2 actual2
      +'
     ++
     ++test_expect_success 'cmd takes precedence over command' '
     ++	test_when_finished "git config --unset trailer.fix.cmd" &&
     ++	git config trailer.fix.ifExists "replace" &&
     ++	git config trailer.fix.cmd "test -n \"\$1\" && git log -1 --oneline --format=\"%h (%aN)\" \
     ++		--abbrev-commit --abbrev=14 \"\$1\" || true" &&
     ++	git config trailer.fix.command "git log -1 --oneline --format=\"%h (%s)\" \
     ++		--abbrev-commit --abbrev=14 \$ARG" &&
     ++	FIXED=$(git log -1 --oneline --format="%h (%aN)" --abbrev-commit --abbrev=14 HEAD) &&
     ++	cat complex_message_body >expected2 &&
     ++	sed -e "s/ Z\$/ /" >>expected2 <<-EOF &&
     ++		Fixes: $FIXED
     ++		Acked-by= Z
     ++		Reviewed-by:
     ++		Signed-off-by: Z
     ++		Signed-off-by: A U Thor <author@example.com>
     ++	EOF
     ++	git interpret-trailers --trailer "review:" --trailer "fix=HEAD" \
     ++		<complex_message >actual2 &&
     ++	test_cmp expected2 actual2
     ++'
      +
       test_expect_success 'with command using $ARG' '
       	git config trailer.fix.ifExists "replace" &&
     @@ trailer.c: struct conf_info {
       	char *name;
       	char *key;
       	char *command;
     -+	int is_new_cmd;
     ++	char *cmd;
       	enum trailer_where where;
       	enum trailer_if_exists if_exists;
       	enum trailer_if_missing if_missing;
     +@@ trailer.c: static void free_arg_item(struct arg_item *item)
     + 	free(item->conf.name);
     + 	free(item->conf.key);
     + 	free(item->conf.command);
     ++	free(item->conf.cmd);
     + 	free(item->token);
     + 	free(item->value);
     + 	free(item);
      @@ trailer.c: static int check_if_different(struct trailer_item *in_tok,
       	return 1;
       }
       
      -static char *apply_command(const char *command, const char *arg)
     -+static char *apply_command(const char *command, int is_new_cmd , const char *arg)
     ++static char *apply_command(const char *command, const char *cmd_, const char *arg)
       {
       	struct strbuf cmd = STRBUF_INIT;
       	struct strbuf buf = STRBUF_INIT;
     -@@ trailer.c: static char *apply_command(const char *command, const char *arg)
     + 	struct child_process cp = CHILD_PROCESS_INIT;
       	char *result;
       
     - 	strbuf_addstr(&cmd, command);
     +-	strbuf_addstr(&cmd, command);
      -	if (arg)
      -		strbuf_replace(&cmd, TRAILER_ARG_STRING, arg);
      -
     - 	strvec_push(&cp.args, cmd.buf);
     -+	if (arg) {
     -+		if (is_new_cmd)
     +-	strvec_push(&cp.args, cmd.buf);
     ++	if (cmd_) {
     ++		strbuf_addstr(&cmd, cmd_);
     ++		strvec_push(&cp.args, cmd.buf);
     ++		if (arg)
      +			strvec_push(&cp.args, arg);
     -+		else
     ++	} else if (command) {
     ++		strbuf_addstr(&cmd, command);
     ++		strvec_push(&cp.args, cmd.buf);
     ++		if (arg)
      +			strbuf_replace(&cmd, TRAILER_ARG_STRING, arg);
      +	}
       	cp.env = local_repo_env;
       	cp.no_stdin = 1;
       	cp.use_shell = 1;
     +@@ trailer.c: static char *apply_command(const char *command, const char *arg)
     + 
     + static void apply_item_command(struct trailer_item *in_tok, struct arg_item *arg_tok)
     + {
     +-	if (arg_tok->conf.command) {
     ++	if (arg_tok->conf.command || arg_tok->conf.cmd) {
     + 		const char *arg;
     + 		if (arg_tok->value && arg_tok->value[0]) {
     + 			arg = arg_tok->value;
      @@ trailer.c: static void apply_item_command(struct trailer_item *in_tok, struct arg_item *arg
       			else
       				arg = xstrdup("");
       		}
      -		arg_tok->value = apply_command(arg_tok->conf.command, arg);
     -+		arg_tok->value = apply_command(arg_tok->conf.command, arg_tok->conf.is_new_cmd, arg);
     ++		arg_tok->value = apply_command(arg_tok->conf.command, arg_tok->conf.cmd, arg);
       		free((char *)arg);
       	}
       }
     +@@ trailer.c: static void duplicate_conf(struct conf_info *dst, const struct conf_info *src)
     + 	dst->name = xstrdup_or_null(src->name);
     + 	dst->key = xstrdup_or_null(src->key);
     + 	dst->command = xstrdup_or_null(src->command);
     ++	dst->cmd = xstrdup_or_null(src->cmd);
     + }
     + 
     + static struct arg_item *get_conf_item(const char *name)
      @@ trailer.c: static struct arg_item *get_conf_item(const char *name)
       	return item;
       }
     @@ trailer.c: static struct {
       	{ "ifexists", TRAILER_IF_EXISTS },
       	{ "ifmissing", TRAILER_IF_MISSING }
      @@ trailer.c: static int git_trailer_config(const char *conf_key, const char *value, void *cb)
     - 	case TRAILER_COMMAND:
     - 		if (conf->command)
       			warning(_("more than one %s"), conf_key);
     -+		conf->is_new_cmd = 0;
     -+		conf->command = xstrdup(value);
     -+		break;
     -+	case TRAILER_CMD:
     -+		if (conf->command)
     -+			warning(_("more than one %s"), conf_key);
     -+		conf->is_new_cmd = 1;
       		conf->command = xstrdup(value);
       		break;
     ++	case TRAILER_CMD:
     ++		if (conf->cmd)
     ++			warning(_("more than one %s"), conf_key);
     ++		conf->cmd = xstrdup(value);
     ++		break;
       	case TRAILER_WHERE:
     + 		if (trailer_set_where(&conf->where, value))
     + 			warning(_("unknown value '%s' for key '%s'"), value, conf_key);
     +@@ trailer.c: static void process_command_line_args(struct list_head *arg_head,
     + 	/* Add an arg item for each configured trailer with a command */
     + 	list_for_each(pos, &conf_head) {
     + 		item = list_entry(pos, struct arg_item, list);
     +-		if (item->conf.command)
     ++		if (item->conf.cmd || item->conf.command)
     + 			add_arg_item(arg_head,
     + 				     xstrdup(token_from_item(item, NULL)),
     + 				     xstrdup(""),

 Documentation/git-interpret-trailers.txt | 10 ++++++
 t/t7513-interpret-trailers.sh            | 43 +++++++++++++++++++++++-
 trailer.c                                | 37 ++++++++++++++------
 3 files changed, 78 insertions(+), 12 deletions(-)