[PATCH v2] [GSOC]trailer: pass arg as positional parameter

From: ZheNing Hu <adlternative@gmail.com>

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.

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.

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-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-913/adlternative/trailer-pass-ARG-env-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/913

Range-diff vs v1:

 1:  abc5b04d152f ! 1:  185356d6fc90 [GSOC]trailer: change $ARG to environment variable
     @@ Metadata
      Author: ZheNing Hu <adlternative@gmail.com>
      
       ## Commit message ##
     -    [GSOC]trailer: change $ARG to environment variable
     +    [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 then one `$ARG`,
     -    error will occur.
     +    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.
      
     -    So pass `$ARG` as an environment variable to the trailer command,
     -    all `$ARG` in the command will be replaced, which will fix this problem.
     +    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.
     +
     +    Original `trailer.<token>.command` can still be used until git
     +    completely abandoned it.
      
          Signed-off-by: ZheNing Hu <adlternative@gmail.com>
      
       ## Documentation/git-interpret-trailers.txt ##
     -@@ Documentation/git-interpret-trailers.txt: line, where <value> is taken to be the standard output of the
     - specified command with any leading and trailing whitespace trimmed
     - off.
     - +
     --If the command contains the `$ARG` string, this string will be
     -+If the command contains the `$ARG` string (`$ARG` is an exported
     -+environment variable), this string will be
     - replaced with the <value> part of an existing trailer with the same
     - <token>, if any, before the command is launched.
     - +
     +@@ Documentation/git-interpret-trailers.txt: also be executed for each of these arguments. And the <value> part of
     + these arguments, if any, will be used to replace the `$ARG` string in
     + the command.
     + 
     ++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
     ++	trailer value multiple times in the command.
     ++	E.g. `trailer.sign.cmd="test -n \"$1\" && echo \"$1\" || true "`
     ++
     + EXAMPLES
     + --------
     + 
      
       ## t/t7513-interpret-trailers.sh ##
     -@@ t/t7513-interpret-trailers.sh: test_expect_success 'with command using $ARG' '
     - 	test_cmp expected actual
     +@@ t/t7513-interpret-trailers.sh: test_expect_success 'setup a commit' '
     + 	git commit -m "Add file a.txt"
       '
       
     -+test_expect_success 'with command using more than one $ARG' '
     ++test_expect_success 'with cmd using $1' '
     ++	test_when_finished "git config --unset trailer.fix.cmd" &&
      +	git config trailer.fix.ifExists "replace" &&
     -+	git config trailer.fix.command "test -n $ARG && git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG || true" &&
     ++	git config trailer.fix.cmd "test -n \"\$1\" && git log -1 --oneline --format=\"%h (%s)\" \
     ++		--abbrev-commit --abbrev=14 \"\$1\" || true" &&
      +	FIXED=$(git log -1 --oneline --format="%h (%s)" --abbrev-commit --abbrev=14 HEAD) &&
     -+	cat complex_message_body >expected &&
     -+	sed -e "s/ Z\$/ /" >>expected <<-EOF &&
     ++	cat complex_message_body >expected2 &&
     ++	sed -e "s/ Z\$/ /" >>expected2 <<-EOF &&
      +		Fixes: $FIXED
      +		Acked-by= Z
      +		Reviewed-by:
     @@ t/t7513-interpret-trailers.sh: test_expect_success 'with command using $ARG' '
      +		Signed-off-by: A U Thor <author@example.com>
      +	EOF
      +	git interpret-trailers --trailer "review:" --trailer "fix=HEAD" \
     -+		<complex_message >actual &&
     -+	test_cmp expected actual
     ++		<complex_message >actual2 &&
     ++	test_cmp expected2 actual2
      +'
      +
     - test_expect_success 'with failing command using $ARG' '
     + test_expect_success 'with command using $ARG' '
       	git config trailer.fix.ifExists "replace" &&
     - 	git config trailer.fix.command "false \$ARG" &&
     +-	git config trailer.fix.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG" &&
     ++	git config trailer.fix.command "git log -1 --oneline --format=\"%h (%s)\" \
     ++		--abbrev-commit --abbrev=14 \$ARG" &&
     + 	FIXED=$(git log -1 --oneline --format="%h (%s)" --abbrev-commit --abbrev=14 HEAD) &&
     + 	cat complex_message_body >expected &&
     + 	sed -e "s/ Z\$/ /" >>expected <<-EOF &&
      
       ## trailer.c ##
     -@@ trailer.c: static char *separators = ":";
     - 
     - static int configured;
     - 
     --#define TRAILER_ARG_STRING "$ARG"
     -+#define TRAILER_ARG_STRING "ARG"
     +@@ trailer.c: struct conf_info {
     + 	char *name;
     + 	char *key;
     + 	char *command;
     ++	int is_new_cmd;
     + 	enum trailer_where where;
     + 	enum trailer_if_exists if_exists;
     + 	enum trailer_if_missing if_missing;
     +@@ trailer.c: static int check_if_different(struct trailer_item *in_tok,
     + 	return 1;
     + }
       
     - static const char *git_generated_prefixes[] = {
     - 	"Signed-off-by: ",
     -@@ trailer.c: static char *apply_command(const char *command, const char *arg)
     +-static char *apply_command(const char *command, const char *arg)
     ++static char *apply_command(const char *command, int is_new_cmd , const char *arg)
     + {
     + 	struct strbuf cmd = STRBUF_INIT;
       	struct strbuf buf = STRBUF_INIT;
     - 	struct child_process cp = CHILD_PROCESS_INIT;
     +@@ trailer.c: static char *apply_command(const char *command, const char *arg)
       	char *result;
     -+	const char *const *var;
       
       	strbuf_addstr(&cmd, command);
     -+	for (var = local_repo_env; *var; var++)
     -+		strvec_push(&cp.env_array, *var);
     - 	if (arg)
     +-	if (arg)
      -		strbuf_replace(&cmd, TRAILER_ARG_STRING, arg);
     -+		strvec_pushf(&cp.env_array, "%s=%s", TRAILER_ARG_STRING, arg);
     - 
     +-
       	strvec_push(&cp.args, cmd.buf);
     --	cp.env = local_repo_env;
     -+
     ++	if (arg) {
     ++		if (is_new_cmd)
     ++			strvec_push(&cp.args, arg);
     ++		else
     ++			strbuf_replace(&cmd, TRAILER_ARG_STRING, arg);
     ++	}
     + 	cp.env = local_repo_env;
       	cp.no_stdin = 1;
       	cp.use_shell = 1;
     +@@ 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);
     + 		free((char *)arg);
     + 	}
     + }
     +@@ trailer.c: static struct arg_item *get_conf_item(const char *name)
     + 	return item;
     + }
     + 
     +-enum trailer_info_type { TRAILER_KEY, TRAILER_COMMAND, TRAILER_WHERE,
     +-			 TRAILER_IF_EXISTS, TRAILER_IF_MISSING };
     ++enum trailer_info_type { TRAILER_KEY, TRAILER_COMMAND, TRAILER_CMD,
     ++			TRAILER_WHERE, TRAILER_IF_EXISTS, TRAILER_IF_MISSING };
       
     + static struct {
     + 	const char *name;
     +@@ trailer.c: static struct {
     + } trailer_config_items[] = {
     + 	{ "key", TRAILER_KEY },
     + 	{ "command", TRAILER_COMMAND },
     ++	{ "cmd", TRAILER_CMD },
     + 	{ "where", TRAILER_WHERE },
     + 	{ "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_WHERE:

 Documentation/git-interpret-trailers.txt |  7 +++++++
 t/t7513-interpret-trailers.sh            | 22 +++++++++++++++++++-
 trailer.c                                | 26 +++++++++++++++++-------
 3 files changed, 47 insertions(+), 8 deletions(-)