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From: Junio C Hamano <gitster@pobox•com>
To: Phillip Wood <phillip.wood123@gmail•com>
Cc: "D. Ben Knoble" <ben.knoble+github@gmail•com>,
	git@vger•kernel.org, "Noah Pendleton" <noah.pendleton@gmail•com>,
	"Patrick Steinhardt" <ps@pks•im>,
	"Thranur Andul" <thranur@gmail•com>,
	"Michael Grosser" <grosser.michael@gmail•com>,
	"Eric Sunshine" <sunshine@sunshineco•com>,
	"Taylor Blau" <me@ttaylorr•com>,
	"Matheus Tavares" <matheus.tavb@gmail•com>,
	"Johannes Schindelin" <Johannes.Schindelin@gmx•de>,
	"Calvin Wan" <calvinwan@google•com>,
	"brian m. carlson" <sandals@crustytoothpaste•net>,
	"Martin Ågren" <martin.agren@gmail•com>
Subject: Re: [PATCH v2 2/3] config: values of pathname type can be prefixed with :(optional)
Date: Mon, 06 Oct 2025 13:22:41 -0700	[thread overview]
Message-ID: <xmqqikgrok4u.fsf@gitster.g> (raw)
In-Reply-To: <xmqqms63ok7g.fsf@gitster.g> (Junio C. Hamano's message of "Mon, 06 Oct 2025 13:21:07 -0700")

Junio C Hamano <gitster@pobox•com> writes:

> So, here is the preliminary clea-up step that should come before
> [2/3]
>
> --- >8 ---
> Subject: [PATCH] t7500: fix GIT_EDITOR shell snippet

And this is [2/3] rebased on top.

--- >8 ---
Subject: [PATCH] config: values of pathname type can be prefixed with :(optional)

Sometimes people want to specify additional configuration data
as "best effort" basis.  Maybe commit.template configuration file points
at somewhere in ~/template/ but on a particular system, the file may not
exist and the user may be OK without using the template in such a case.

When the value given to a configuration variable whose type is
pathname wants to signal such an optional file, it can be marked by
prepending ":(optional)" in front of it.  Such a setting that is
marked optional would avoid getting the command barf for a missing
file, as an optional configuration setting that names a missing
file is not even seen.

cf. <xmqq5ywehb69.fsf@gitster•g>

Signed-off-by: Junio C Hamano <gitster@pobox•com>
Signed-off-by: Taylor Blau <me@ttaylorr•com>
Signed-off-by: D. Ben Knoble <ben.knoble+github@gmail•com>
Signed-off-by: Junio C Hamano <gitster@pobox•com>
---
 Documentation/config.adoc                 |  4 +++-
 config.c                                  | 16 ++++++++++++++--
 t/t7500-commit-template-squash-signoff.sh |  8 ++++++++
 wrapper.c                                 | 13 +++++++++++++
 wrapper.h                                 |  4 +++-
 5 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/Documentation/config.adoc b/Documentation/config.adoc
index cc769251be..7301ced836 100644
--- a/Documentation/config.adoc
+++ b/Documentation/config.adoc
@@ -358,7 +358,9 @@ compiled without runtime prefix support, the compiled-in prefix will be
 substituted instead. In the unlikely event that a literal path needs to
 be specified that should _not_ be expanded, it needs to be prefixed by
 `./`, like so: `./%(prefix)/bin`.
-
++
+If prefixed with `:(optional)`, the configuration variable is treated
+as if it does not exist, if the named path does not exist.
 
 Variables
 ~~~~~~~~~
diff --git a/config.c b/config.c
index 97ffef4270..73fc74c8fa 100644
--- a/config.c
+++ b/config.c
@@ -1279,11 +1279,23 @@ int git_config_string(char **dest, const char *var, const char *value)
 
 int git_config_pathname(char **dest, const char *var, const char *value)
 {
+	int is_optional;
+	char *path;
+
 	if (!value)
 		return config_error_nonbool(var);
-	*dest = interpolate_path(value, 0);
-	if (!*dest)
+
+	is_optional = skip_prefix(value, ":(optional)", &value);
+	path = interpolate_path(value, 0);
+	if (!path)
 		die(_("failed to expand user dir in: '%s'"), value);
+
+	if (is_optional && is_missing_file(path)) {
+		free(path);
+		return 0;
+	}
+
+	*dest = path;
 	return 0;
 }
 
diff --git a/t/t7500-commit-template-squash-signoff.sh b/t/t7500-commit-template-squash-signoff.sh
index 4922543256..a85229e556 100755
--- a/t/t7500-commit-template-squash-signoff.sh
+++ b/t/t7500-commit-template-squash-signoff.sh
@@ -46,6 +46,14 @@ test_expect_success 'nonexistent template file in config should return error' '
 	)
 '
 
+test_expect_success 'nonexistent optional template file in config' '
+	test_config commit.template ":(optional)$PWD"/notexist &&
+	GIT_EDITOR="echo hello >" git commit --allow-empty &&
+	git cat-file commit HEAD | sed -e "1,/^$/d" >actual &&
+	echo hello >expect &&
+	test_cmp expect actual
+'
+
 # From now on we'll use a template file that exists.
 TEMPLATE="$PWD"/template
 
diff --git a/wrapper.c b/wrapper.c
index 2f00d2ac87..3d507d4204 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -721,6 +721,19 @@ int xgethostname(char *buf, size_t len)
 	return ret;
 }
 
+int is_missing_file(const char *filename)
+{
+	struct stat st;
+
+	if (stat(filename, &st) < 0) {
+		if (errno == ENOENT)
+			return 1;
+		die_errno(_("could not stat %s"), filename);
+	}
+
+	return 0;
+}
+
 int is_empty_or_missing_file(const char *filename)
 {
 	struct stat st;
diff --git a/wrapper.h b/wrapper.h
index 7df824e34a..44a8597ac3 100644
--- a/wrapper.h
+++ b/wrapper.h
@@ -66,7 +66,9 @@ void write_file_buf(const char *path, const char *buf, size_t len);
 __attribute__((format (printf, 2, 3)))
 void write_file(const char *path, const char *fmt, ...);
 
-/* Return 1 if the file is empty or does not exists, 0 otherwise. */
+/* Return 1 if the file does not exist, 0 otherwise. */
+int is_missing_file(const char *filename);
+/* Return 1 if the file is empty or does not exist, 0 otherwise. */
 int is_empty_or_missing_file(const char *filename);
 
 enum fsync_action {
-- 
2.51.0-580-g8258b70b6e


  reply	other threads:[~2025-10-06 20:22 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-07 20:27 [PATCH 0/1] blame: Skip missing ignore-revs file Noah Pendleton
2021-08-07 20:58 ` Junio C Hamano
2021-08-07 21:34   ` Noah Pendleton
2021-08-08  5:43     ` Junio C Hamano
2021-08-08 17:50       ` Junio C Hamano
2021-08-08 18:21         ` Noah Pendleton
2021-08-09 15:47           ` Junio C Hamano
2024-10-14 20:44             ` [PATCH 0/3] specifying a file that can optionally exist Junio C Hamano
2024-10-14 20:44               ` [PATCH 1/3] t7500: make each piece more independent Junio C Hamano
2024-10-14 20:44               ` [PATCH 2/3] config: values of pathname type can be prefixed with :(optional) Junio C Hamano
2024-10-14 20:44               ` [PATCH 3/3] parseopt: " Junio C Hamano
2025-05-01 21:40             ` [PATCH 0/3] specifying a file that can optionally exist Junio C Hamano
2025-05-01 21:40               ` [PATCH 1/3] t7500: make each piece more independent Junio C Hamano
2025-05-01 21:40               ` [PATCH 2/3] config: values of pathname type can be prefixed with :(optional) Junio C Hamano
2025-05-02  8:52                 ` Patrick Steinhardt
2025-05-02 14:28                   ` Phillip Wood
2025-05-02 20:05                   ` Junio C Hamano
2025-05-01 21:40               ` [PATCH 3/3] parseopt: " Junio C Hamano
2025-09-28 21:29               ` [PATCH v2 0/3] Support :(optional) filepaths D. Ben Knoble
2025-09-28 21:29                 ` [PATCH v2 1/3] t7500: make each piece more independent D. Ben Knoble
2025-09-28 21:29                 ` [PATCH v2 2/3] config: values of pathname type can be prefixed with :(optional) D. Ben Knoble
2025-09-30 15:26                   ` Phillip Wood
2025-10-06 19:00                     ` Junio C Hamano
2025-10-06 19:59                       ` Junio C Hamano
2025-10-06 20:21                         ` Junio C Hamano
2025-10-06 20:22                           ` Junio C Hamano [this message]
2025-10-07 12:24                           ` Kristoffer Haugsbakk
2025-10-07 17:04                             ` Junio C Hamano
2025-11-02 16:20                     ` D. Ben Knoble
2025-09-28 21:29                 ` [PATCH v2 3/3] parseopt: " D. Ben Knoble
2025-09-30 15:26                   ` Phillip Wood
2025-11-02 16:20                     ` D. Ben Knoble
2025-11-03  0:10                       ` Eric Sunshine
2025-11-04 18:22                         ` D. Ben Knoble
2025-09-28 22:40                 ` [PATCH v2 0/3] Support :(optional) filepaths Junio C Hamano
2025-09-29 16:42                   ` Ben Knoble
2025-10-20  9:40                 ` [PATCH] t7500: fix tests with absolute path following ":(optional)" on Windows Johannes Sixt
2025-10-20 13:43                   ` Ben Knoble
2025-10-20 17:32                     ` Johannes Sixt
2025-10-20 18:06                       ` Junio C Hamano
2025-10-20 20:27                       ` D. Ben Knoble
2025-10-20 20:27                         ` D. Ben Knoble
2025-10-20 17:39                     ` Eric Sunshine
2025-10-20 16:17                   ` Junio C Hamano
2025-10-20 17:24                     ` Johannes Sixt
2022-03-04  9:51   ` [PATCH 0/1] blame: Skip missing ignore-revs file Thranur Andul
2021-08-08 17:48 ` [PATCH v2] blame: add config `blame.ignoreRevsFileIsOptional` Noah Pendleton
  -- strict thread matches above, loose matches on Subject: below --
2025-04-25 18:41 Feature request: automatically read .git-blame-ignore-revs or allow global optional config Michael Grosser
2025-04-25 19:54 ` Eric Sunshine
2025-05-01 18:00   ` D. Ben Knoble
2025-05-01 18:28     ` Eric Sunshine

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