Merge branch 'jk/trailers-parse'

"git interpret-trailers" has been taught a "--parse" and a few
other options to make it easier for scripts to grab existing
trailer lines from a commit log message.

* jk/trailers-parse:
  doc/interpret-trailers: fix "the this" typo
  pretty: support normalization options for %(trailers)
  t4205: refactor %(trailers) tests
  pretty: move trailer formatting to trailer.c
  interpret-trailers: add --parse convenience option
  interpret-trailers: add an option to unfold values
  interpret-trailers: add an option to show only existing trailers
  interpret-trailers: add an option to show only the trailers
  trailer: put process_trailers() options into a struct

Documentation/git-interpret-trailers.txt

@@ -3,24 +3,27 @@ git-interpret-trailers(1)
 
 NAME
 ----
-git-interpret-trailers - help add structured information into commit messages
+git-interpret-trailers - add or parse structured information in commit messages
 
 SYNOPSIS
 --------
 [verse]
-'git interpret-trailers' [--in-place] [--trim-empty] [(--trailer <token>[(=|:)<value>])...] [<file>...]
+'git interpret-trailers' [options] [(--trailer <token>[(=|:)<value>])...] [<file>...]
+'git interpret-trailers' [options] [--parse] [<file>...]
 
 DESCRIPTION
 -----------
-Help adding 'trailers' lines, that look similar to RFC 822 e-mail
+Help parsing or adding 'trailers' lines, that look similar to RFC 822 e-mail
 headers, at the end of the otherwise free-form part of a commit
 message.
 
 This command reads some patches or commit messages from either the
-<file> arguments or the standard input if no <file> is specified. Then
-this command applies the arguments passed using the `--trailer`
-option, if any, to the commit message part of each input file. The
-result is emitted on the standard output.
+<file> arguments or the standard input if no <file> is specified. If
+`--parse` is specified, the output consists of the parsed trailers.
+
+Otherwise, this command applies the arguments passed using the
+`--trailer` option, if any, to the commit message part of each input
+file. The result is emitted on the standard output.
 
 Some configuration variables control the way the `--trailer` arguments
 are applied to each commit message and the way any existing trailer in
@@ -103,6 +106,22 @@ OPTIONS
 	and applies to all '--trailer' options until the next occurrence of
 	'--if-missing' or '--no-if-missing'.
 
+--only-trailers::
+	Output only the trailers, not any other parts of the input.
+
+--only-input::
+	Output only trailers that exist in the input; do not add any
+	from the command-line or by following configured `trailer.*`
+	rules.
+
+--unfold::
+	Remove any whitespace-continuation in trailers, so that each
+	trailer appears on a line by itself with its full content.
+
+--parse::
+	A convenience alias for `--only-trailers --only-input
+	--unfold`.
+
 CONFIGURATION VARIABLES
 -----------------------
 

Documentation/pretty-formats.txt

@@ -205,7 +205,10 @@ endif::git-rev-list[]
 - '%><(<N>)', '%><|(<N>)': similar to '% <(<N>)', '%<|(<N>)'
   respectively, but padding both sides (i.e. the text is centered)
 - %(trailers): display the trailers of the body as interpreted by
-  linkgit:git-interpret-trailers[1]
+  linkgit:git-interpret-trailers[1]. If the `:only` option is given,
+  omit non-trailer lines from the trailer block.  If the `:unfold`
+  option is given, behave as if interpret-trailer's `--unfold` option
+  was given. E.g., `%(trailers:only:unfold)` to do both.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will

builtin/interpret-trailers.c

@@ -73,15 +73,24 @@ static int option_parse_trailer(const struct option *opt,
 	return 0;
 }
 
+static int parse_opt_parse(const struct option *opt, const char *arg,
+			   int unset)
+{
+	struct process_trailer_options *v = opt->value;
+	v->only_trailers = 1;
+	v->only_input = 1;
+	v->unfold = 1;
+	return 0;
+}
+
 int cmd_interpret_trailers(int argc, const char **argv, const char *prefix)
 {
-	int in_place = 0;
-	int trim_empty = 0;
+	struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
 	LIST_HEAD(trailers);
 
 	struct option options[] = {
-		OPT_BOOL(0, "in-place", &in_place, N_("edit files in place")),
-		OPT_BOOL(0, "trim-empty", &trim_empty, N_("trim empty trailers")),
+		OPT_BOOL(0, "in-place", &opts.in_place, N_("edit files in place")),
+		OPT_BOOL(0, "trim-empty", &opts.trim_empty, N_("trim empty trailers")),
 
 		OPT_CALLBACK(0, "where", NULL, N_("action"),
 			     N_("where to place the new trailer"), option_parse_where),
@@ -90,6 +99,11 @@ int cmd_interpret_trailers(int argc, const char **argv, const char *prefix)
 		OPT_CALLBACK(0, "if-missing", NULL, N_("action"),
 			     N_("action if trailer is missing"), option_parse_if_missing),
 
+		OPT_BOOL(0, "only-trailers", &opts.only_trailers, N_("output only the trailers")),
+		OPT_BOOL(0, "only-input", &opts.only_input, N_("do not apply config rules")),
+		OPT_BOOL(0, "unfold", &opts.unfold, N_("join whitespace-continued values")),
+		{ OPTION_CALLBACK, 0, "parse", &opts, NULL, N_("set parsing options"),
+			PARSE_OPT_NOARG | PARSE_OPT_NONEG, parse_opt_parse },
 		OPT_CALLBACK(0, "trailer", &trailers, N_("trailer"),
 				N_("trailer(s) to add"), option_parse_trailer),
 		OPT_END()
@@ -98,14 +112,20 @@ int cmd_interpret_trailers(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options,
 			     git_interpret_trailers_usage, 0);
 
+	if (opts.only_input && !list_empty(&trailers))
+		usage_msg_opt(
+			_("--trailer with --only-input does not make sense"),
+			git_interpret_trailers_usage,
+			options);
+
 	if (argc) {
 		int i;
 		for (i = 0; i < argc; i++)
-			process_trailers(argv[i], in_place, trim_empty, &trailers);
+			process_trailers(argv[i], &opts, &trailers);
 	} else {
-		if (in_place)
+		if (opts.in_place)
 			die(_("no input file given for in-place editing"));
-		process_trailers(NULL, in_place, trim_empty, &trailers);
+		process_trailers(NULL, &opts, &trailers);
 	}
 
 	new_trailers_clear(&trailers);

pretty.c

@@ -871,16 +871,6 @@ const char *format_subject(struct strbuf *sb, const char *msg,
 	return msg;
 }
 
-static void format_trailers(struct strbuf *sb, const char *msg)
-{
-	struct trailer_info info;
-
-	trailer_info_get(&info, msg);
-	strbuf_add(sb, info.trailer_start,
-		   info.trailer_end - info.trailer_start);
-	trailer_info_release(&info);
-}
-
 static void parse_commit_message(struct format_commit_context *c)
 {
 	const char *msg = c->message + c->message_off;
@@ -1074,6 +1064,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 	const struct commit *commit = c->commit;
 	const char *msg = c->message;
 	struct commit_list *p;
+	const char *arg;
 	int ch;
 
 	/* these are independent of the commit */
@@ -1292,9 +1283,18 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		return 1;
 	}
 
-	if (starts_with(placeholder, "(trailers)")) {
-		format_trailers(sb, msg + c->subject_off);
-		return strlen("(trailers)");
+	if (skip_prefix(placeholder, "(trailers", &arg)) {
+		struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
+		while (*arg == ':') {
+			if (skip_prefix(arg, ":only", &arg))
+				opts.only_trailers = 1;
+			else if (skip_prefix(arg, ":unfold", &arg))
+				opts.unfold = 1;
+		}
+		if (*arg == ')') {
+			format_trailers_from_commit(sb, msg + c->subject_off, &opts);
+			return arg - placeholder + 1;
+		}
 	}
 
 	return 0;	/* unknown placeholder */

t/t4205-log-pretty-formats.sh

@@ -539,25 +539,62 @@ cat >trailers <<EOF
 Signed-off-by: A U Thor <author@example.com>
 Acked-by: A U Thor <author@example.com>
 [ v2 updated patch description ]
-Signed-off-by: A U Thor <author@example.com>
+Signed-off-by: A U Thor
+  <author@example.com>
 EOF
 
-test_expect_success 'pretty format %(trailers) shows trailers' '
+unfold () {
+	perl -0pe 's/\n\s+/ /'
+}
+
+test_expect_success 'set up trailer tests' '
 	echo "Some contents" >trailerfile &&
 	git add trailerfile &&
-	git commit -F - <<-EOF &&
+	git commit -F - <<-EOF
 	trailers: this commit message has trailers
 
 	This commit is a test commit with trailers at the end. We parse this
-	message and display the trailers using %bT
+	message and display the trailers using %(trailers).
 
 	$(cat trailers)
 	EOF
+'
+
+test_expect_success 'pretty format %(trailers) shows trailers' '
 	git log --no-walk --pretty="%(trailers)" >actual &&
-	cat >expect <<-EOF &&
-	$(cat trailers)
+	{
+		cat trailers &&
+		echo
+	} >expect &&
+	test_cmp expect actual
+'
 
-	EOF
+test_expect_success '%(trailers:only) shows only "key: value" trailers' '
+	git log --no-walk --pretty="%(trailers:only)" >actual &&
+	{
+		grep -v patch.description <trailers &&
+		echo
+	} >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(trailers:unfold) unfolds trailers' '
+	git log --no-walk --pretty="%(trailers:unfold)" >actual &&
+	{
+		unfold <trailers &&
+		echo
+	} >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success ':only and :unfold work together' '
+	git log --no-walk --pretty="%(trailers:only:unfold)" >actual &&
+	git log --no-walk --pretty="%(trailers:unfold:only)" >reverse &&
+	test_cmp actual reverse &&
+	{
+		grep -v patch.description <trailers | unfold &&
+		echo
+	} >expect &&
 	test_cmp expect actual
 '
 

t/t7513-interpret-trailers.sh

@@ -1341,4 +1341,80 @@ test_expect_success 'with cut line' '
 	test_cmp expected actual
 '
 
+test_expect_success 'only trailers' '
+	git config trailer.sign.command "echo config-value" &&
+	cat >expected <<-\EOF &&
+		existing: existing-value
+		sign: config-value
+		added: added-value
+	EOF
+	git interpret-trailers \
+		--trailer added:added-value \
+		--only-trailers >actual <<-\EOF &&
+		my subject
+
+		my body
+
+		existing: existing-value
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'only-trailers omits non-trailer in middle of block' '
+	git config trailer.sign.command "echo config-value" &&
+	cat >expected <<-\EOF &&
+		Signed-off-by: nobody <nobody@nowhere>
+		Signed-off-by: somebody <somebody@somewhere>
+		sign: config-value
+	EOF
+	git interpret-trailers --only-trailers >actual <<-\EOF &&
+		subject
+
+		it is important that the trailers below are signed-off-by
+		so that they meet the "25% trailers Git knows about" heuristic
+
+		Signed-off-by: nobody <nobody@nowhere>
+		this is not a trailer
+		Signed-off-by: somebody <somebody@somewhere>
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'only input' '
+	git config trailer.sign.command "echo config-value" &&
+	cat >expected <<-\EOF &&
+		existing: existing-value
+	EOF
+	git interpret-trailers \
+		--only-trailers --only-input >actual <<-\EOF &&
+		my subject
+
+		my body
+
+		existing: existing-value
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'unfold' '
+	cat >expected <<-\EOF &&
+		foo: continued across several lines
+	EOF
+	# pass through tr to make leading and trailing whitespace more obvious
+	tr _ " " <<-\EOF |
+		my subject
+
+		my body
+
+		foo:_
+		__continued
+		___across
+		____several
+		_____lines
+		___
+	EOF
+	git interpret-trailers --only-trailers --only-input --unfold >actual &&
+	test_cmp expected actual
+'
+
 test_done

trailer.c

@@ -159,13 +159,15 @@ static void print_tok_val(FILE *outfile, const char *tok, const char *val)
 		fprintf(outfile, "%s%c %s\n", tok, separators[0], val);
 }
 
-static void print_all(FILE *outfile, struct list_head *head, int trim_empty)
+static void print_all(FILE *outfile, struct list_head *head,
+		      const struct process_trailer_options *opts)
 {
 	struct list_head *pos;
 	struct trailer_item *item;
 	list_for_each(pos, head) {
 		item = list_entry(pos, struct trailer_item, list);
-		if (!trim_empty || strlen(item->value) > 0)
+		if ((!opts->trim_empty || strlen(item->value) > 0) &&
+		    (!opts->only_trailers || item->token))
 			print_tok_val(outfile, item->token, item->value);
 	}
 }
@@ -910,9 +912,37 @@ static int ends_with_blank_line(const char *buf, size_t len)
 	return is_blank_line(buf + ll);
 }
 
+static void unfold_value(struct strbuf *val)
+{
+	struct strbuf out = STRBUF_INIT;
+	size_t i;
+
+	strbuf_grow(&out, val->len);
+	i = 0;
+	while (i < val->len) {
+		char c = val->buf[i++];
+		if (c == '\n') {
+			/* Collapse continuation down to a single space. */
+			while (i < val->len && isspace(val->buf[i]))
+				i++;
+			strbuf_addch(&out, ' ');
+		} else {
+			strbuf_addch(&out, c);
+		}
+	}
+
+	/* Empty lines may have left us with whitespace cruft at the edges */
+	strbuf_trim(&out);
+
+	/* output goes back to val as if we modified it in-place */
+	strbuf_swap(&out, val);
+	strbuf_release(&out);
+}
+
 static int process_input_file(FILE *outfile,
 			      const char *str,
-			      struct list_head *head)
+			      struct list_head *head,
+			      const struct process_trailer_options *opts)
 {
 	struct trailer_info info;
 	struct strbuf tok = STRBUF_INIT;
@@ -922,9 +952,10 @@ static int process_input_file(FILE *outfile,
 	trailer_info_get(&info, str);
 
 	/* Print lines before the trailers as is */
+	if (!opts->only_trailers)
 		fwrite(str, 1, info.trailer_start - str, outfile);
 
-	if (!info.blank_line_before_trailer)
+	if (!opts->only_trailers && !info.blank_line_before_trailer)
 		fprintf(outfile, "\n");
 
 	for (i = 0; i < info.trailer_nr; i++) {
@@ -936,10 +967,12 @@ static int process_input_file(FILE *outfile,
 		if (separator_pos >= 1) {
 			parse_trailer(&tok, &val, NULL, trailer,
 				      separator_pos);
+			if (opts->unfold)
+				unfold_value(&val);
 			add_trailer_item(head,
 					 strbuf_detach(&tok, NULL),
 					 strbuf_detach(&val, NULL));
-		} else {
+		} else if (!opts->only_trailers) {
 			strbuf_addstr(&val, trailer);
 			strbuf_strip_suffix(&val, "\n");
 			add_trailer_item(head,
@@ -993,11 +1026,11 @@ static FILE *create_in_place_tempfile(const char *file)
 	return outfile;
 }
 
-void process_trailers(const char *file, int in_place, int trim_empty,
+void process_trailers(const char *file,
+		      const struct process_trailer_options *opts,
 		      struct list_head *new_trailer_head)
 {
 	LIST_HEAD(head);
-	LIST_HEAD(arg_head);
 	struct strbuf sb = STRBUF_INIT;
 	int trailer_end;
 	FILE *outfile = stdout;
@@ -1006,24 +1039,27 @@ void process_trailers(const char *file, int in_place, int trim_empty,
 
 	read_input_file(&sb, file);
 
-	if (in_place)
+	if (opts->in_place)
 		outfile = create_in_place_tempfile(file);
 
 	/* Print the lines before the trailers */
-	trailer_end = process_input_file(outfile, sb.buf, &head);
+	trailer_end = process_input_file(outfile, sb.buf, &head, opts);
 
+	if (!opts->only_input) {
+		LIST_HEAD(arg_head);
 		process_command_line_args(&arg_head, new_trailer_head);
-
 		process_trailers_lists(&head, &arg_head);
+	}
 
-	print_all(outfile, &head, trim_empty);
+	print_all(outfile, &head, opts);
 
 	free_all(&head);
 
 	/* Print the lines after the trailers as is */
+	if (!opts->only_trailers)
 		fwrite(sb.buf + trailer_end, 1, sb.len - trailer_end, outfile);
 
-	if (in_place)
+	if (opts->in_place)
 		if (rename_tempfile(&trailers_tempfile, file))
 			die_errno(_("could not rename temporary file to %s"), file);
 
@@ -1080,3 +1116,49 @@ void trailer_info_release(struct trailer_info *info)
 		free(info->trailers[i]);
 	free(info->trailers);
 }
+
+static void format_trailer_info(struct strbuf *out,
+				const struct trailer_info *info,
+				const struct process_trailer_options *opts)
+{
+	int i;
+
+	/* If we want the whole block untouched, we can take the fast path. */
+	if (!opts->only_trailers && !opts->unfold) {
+		strbuf_add(out, info->trailer_start,
+			   info->trailer_end - info->trailer_start);
+		return;
+	}
+
+	for (i = 0; i < info->trailer_nr; i++) {
+		char *trailer = info->trailers[i];
+		int separator_pos = find_separator(trailer, separators);
+
+		if (separator_pos >= 1) {
+			struct strbuf tok = STRBUF_INIT;
+			struct strbuf val = STRBUF_INIT;
+
+			parse_trailer(&tok, &val, NULL, trailer, separator_pos);
+			if (opts->unfold)
+				unfold_value(&val);
+
+			strbuf_addf(out, "%s: %s\n", tok.buf, val.buf);
+			strbuf_release(&tok);
+			strbuf_release(&val);
+
+		} else if (!opts->only_trailers) {
+			strbuf_addstr(out, trailer);
+		}
+	}
+
+}
+
+void format_trailers_from_commit(struct strbuf *out, const char *msg,
+				 const struct process_trailer_options *opts)
+{
+	struct trailer_info info;
+
+	trailer_info_get(&info, msg);
+	format_trailer_info(out, &info, opts);
+	trailer_info_release(&info);
+}

trailer.h

@@ -63,11 +63,36 @@ struct new_trailer_item {
 	enum trailer_if_missing if_missing;
 };
 
-void process_trailers(const char *file, int in_place, int trim_empty,
+struct process_trailer_options {
+	int in_place;
+	int trim_empty;
+	int only_trailers;
+	int only_input;
+	int unfold;
+};
+
+#define PROCESS_TRAILER_OPTIONS_INIT {0}
+
+void process_trailers(const char *file,
+		      const struct process_trailer_options *opts,
 		      struct list_head *new_trailer_head);
 
 void trailer_info_get(struct trailer_info *info, const char *str);
 
 void trailer_info_release(struct trailer_info *info);
 
+/*
+ * Format the trailers from the commit msg "msg" into the strbuf "out".
+ * Note two caveats about "opts":
+ *
+ *   - this is primarily a helper for pretty.c, and not
+ *     all of the flags are supported.
+ *
+ *   - this differs from process_trailers slightly in that we always format
+ *     only the trailer block itself, even if the "only_trailers" option is not
+ *     set.
+ */
+void format_trailers_from_commit(struct strbuf *out, const char *msg,
+				 const struct process_trailer_options *opts);
+
 #endif /* TRAILER_H */