Subject: [GSoC PATCH v11 5/5] repo: add the --format flag

From: Lucas Seiki Oshiro <[email-masked]>
Date: Sat, 16 Aug 2025 19:46:03 -0300

Add the --format flag to git-repo-info. By using this flag, the users
can choose the format for obtaining the data they requested.

Given that this command can be used for generating input for other
applications and for being read by end users, it requires at least two
formats: one for being read by humans and other for being read by
machines. Some other Git commands also have two output formats, notably
git-config which was the inspiration for the two formats that were
chosen here:

- keyvalue, where the retrieved data is printed one per line, using =
  for delimiting the key and the value. This is the default format,
  targeted for end users.
- nul, where the retrieved data is separated by NUL characters, using
  the newline character for delimiting the key and the value. This
  format is targeted for being read by machines.

Helped-by: Phillip Wood <[email-masked]>
Helped-by: Junio C Hamano <[email-masked]>
Helped-by: Justin Tobler <[email-masked]>
Helped-by: Eric Sunshine <[email-masked]>
Mentored-by: Karthik Nayak <[email-masked]>
Mentored-by: Patrick Steinhardt <[email-masked]>
Signed-off-by: Lucas Seiki Oshiro <[email-masked]>
---
 Documentation/git-repo.adoc | 40 ++++++++++++++++++++++++++------
 builtin/repo.c              | 46 ++++++++++++++++++++++++++++++++-----
 t/t1900-repo.sh             | 18 ++++++++++++---
 3 files changed, 88 insertions(+), 16 deletions(-)

diff --git a/Documentation/git-repo.adoc b/Documentation/git-repo.adoc
index 01b7f9c95e..2870828d93 100644
--- a/Documentation/git-repo.adoc
+++ b/Documentation/git-repo.adoc
@@ -8,7 +8,7 @@ git-repo - Retrieve information about the repository
 SYNOPSIS
 --------
 [synopsis]
-git repo info [<key>...]
+git repo info [--format=(keyvalue|nul)] [<key>...]
 
 DESCRIPTION
 -----------
@@ -18,7 +18,7 @@ THIS COMMAND IS EXPERIMENTAL. THE BEHAVIOR MAY CHANGE.
 
 COMMANDS
 --------
-`info [<key>...]`::
+`info [--format=(keyvalue|nul)] [<key>...]`::
 	Retrieve metadata-related information about the current repository. Only
 	the requested data will be returned based on their keys (see "INFO KEYS"
 	section below).
@@ -26,14 +26,23 @@ COMMANDS
 The values are returned in the same order in which their respective keys were
 requested.
 +
-The output format consists of key-value pairs one per line using the `=`
-character as the delimiter between the key and the value. Values containing
-"unusual" characters are quoted as explained for the configuration variable
-`core.quotePath` (see linkgit:git-config[1]).
+The output format can be chosen through the flag `--format`. Two formats are
+supported:
++
+`keyvalue`:::
+	output key-value pairs one per line using the `=` character as
+	the delimiter between the key and the value. Values containing "unusual"
+	characters are quoted as explained for the configuration variable
+	`core.quotePath` (see linkgit:git-config[1]). This is the default.
+
+`nul`:::
+	similar to `keyvalue`, but using a newline character as the delimiter
+	between the key and the value and using a NUL character after each value.
+	This format is better suited for being parsed by another applications than
+	`keyvalue`. Unlike in the `keyvalue` format, the values are never quoted.
 
 INFO KEYS
 ---------
-
 In order to obtain a set of values from `git repo info`, you should provide
 the keys that identify them. Here's a list of the available keys and the
 values that they return:
@@ -49,6 +58,23 @@ values that they return:
 +
 include::ref-storage-format.adoc[]
 
+EXAMPLES
+--------
+
+* Retrieves the reference format of the current repository:
++
+------------
+git repo info references.format
+------------
++
+
+* Retrieves whether the current repository is bare and whether it is shallow
+using the `nul` format:
++
+------------
+git repo info --format=nul layout.bare layout.shallow
+------------
+
 SEE ALSO
 --------
 linkgit:git-rev-parse[1]
diff --git a/builtin/repo.c b/builtin/repo.c
index 3c9140593b..8c6e7f42ab 100644
--- a/builtin/repo.c
+++ b/builtin/repo.c
@@ -9,12 +9,17 @@
 #include "shallow.h"
 
 static const char *const repo_usage[] = {
-	"git repo info [<key>...]",
+	"git repo info [--format=(keyvalue|nul)] [<key>...]",
 	NULL
 };
 
 typedef int get_value_fn(struct repository *repo, struct strbuf *buf);
 
+enum output_format {
+	FORMAT_KEYVALUE,
+	FORMAT_NUL_TERMINATED,
+};
+
 struct field {
 	const char *key;
 	get_value_fn *get_value;
@@ -65,7 +70,9 @@ static get_value_fn *get_value_fn_for_key(const char *key)
 	return found ? found->get_value : NULL;
 }
 
-static int print_fields(int argc, const char **argv, struct repository *repo)
+static int print_fields(int argc, const char **argv,
+			struct repository *repo,
+			enum output_format format)
 {
 	int ret = 0;
 	struct strbuf valbuf = STRBUF_INIT;
@@ -86,8 +93,18 @@ static int print_fields(int argc, const char **argv, struct repository *repo)
 		strbuf_reset(&quotbuf);
 
 		get_value(repo, &valbuf);
-		quote_c_style(valbuf.buf, &quotbuf, NULL, 0);
-		printf("%s=%s\n", key, quotbuf.buf);
+
+		switch (format) {
+		case FORMAT_KEYVALUE:
+			quote_c_style(valbuf.buf, &quotbuf, NULL, 0);
+			printf("%s=%s\n", key, quotbuf.buf);
+			break;
+		case FORMAT_NUL_TERMINATED:
+			printf("%s\n%s%c", key, valbuf.buf, '\0');
+			break;
+		default:
+			BUG("not a valid output format: %d", format);
+		}
 	}
 
 	strbuf_release(&valbuf);
@@ -95,10 +112,27 @@ static int print_fields(int argc, const char **argv, struct repository *repo)
 	return ret;
 }
 
-static int repo_info(int argc, const char **argv, const char *prefix UNUSED,
+static int repo_info(int argc, const char **argv, const char *prefix,
 		     struct repository *repo)
 {
-	return print_fields(argc - 1, argv + 1, repo);
+	const char *format_str = "keyvalue";
+	enum output_format format;
+	struct option options[] = {
+		OPT_STRING(0, "format", &format_str, N_("format"),
+			   N_("output format")),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options, repo_usage, 0);
+
+	if (!strcmp(format_str, "keyvalue"))
+		format = FORMAT_KEYVALUE;
+	else if (!strcmp(format_str, "nul"))
+		format = FORMAT_NUL_TERMINATED;
+	else
+		die(_("invalid format '%s'"), format_str);
+
+	return print_fields(argc, argv, repo, format);
 }
 
 int cmd_repo(int argc, const char **argv, const char *prefix,
diff --git a/t/t1900-repo.sh b/t/t1900-repo.sh
index 6a9cbf3d47..a69c715357 100755
--- a/t/t1900-repo.sh
+++ b/t/t1900-repo.sh
@@ -25,11 +25,17 @@ test_repo_info () {
 		eval "$init_command $repo_name"
 	'
 
-	test_expect_success "$label" '
-		echo "$key=$expected_value" >expect &&
-		git -C $repo_name repo info "$key" >actual &&
+	test_expect_success "keyvalue: $label" '
+		echo "$key=$expected_value" > expect &&
+		git -C "$repo_name" repo info "$key" >actual &&
 		test_cmp expect actual
 	'
+
+	test_expect_success "nul: $label" '
+		printf "%s\n%s\0" "$key" "$expected_value" >expect &&
+		git -C "$repo_name" repo info --format=nul "$key" >actual &&
+		test_cmp_bin expect actual
+	'
 }
 
 test_repo_info 'ref format files is retrieved correctly' \
@@ -80,4 +86,10 @@ test_expect_success 'git-repo-info outputs data even if there is an invalid fiel
 	test_cmp expect actual
 '
 
+test_expect_success 'git-repo-info aborts when requesting an invalid format' '
+	echo "fatal: invalid format ${SQ}foo${SQ}" >expect &&
+	test_must_fail git repo info --format=foo 2>actual &&
+	test_cmp expect actual
+'
+
 test_done
-- 
2.39.5 (Apple Git-154)