linux-kernel - [PATCH v2 2/3] samples/landlock: Refactor --help message in function

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Message-Id: <20241003005042.258991-2-matthieu@buffet.re>
Date: Thu,  3 Oct 2024 02:50:41 +0200
From: Matthieu Buffet <matthieu@...fet.re>
To: Mickaël Salaün <mic@...ikod.net>
Cc: Günther Noack <gnoack@...gle.com>,
	Konstantin Meskhidze <konstantin.meskhidze@...wei.com>,
	Ivanov Mikhail <ivanov.mikhail1@...wei-partners.com>,
	linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Matthieu Buffet <matthieu@...fet.re>
Subject: [PATCH v2 2/3] samples/landlock: Refactor --help message in function

Help message is getting larger with each new supported feature (scopes,
and soon UDP). Refactor it away into a separate helper function.

Signed-off-by: Matthieu Buffet <matthieu@...fet.re>
---
 samples/landlock/sandboxer.c | 87 +++++++++++++++++++-----------------
 1 file changed, 46 insertions(+), 41 deletions(-)

diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
index aff5ef808e22..f16994d35d9e 100644
--- a/samples/landlock/sandboxer.c
+++ b/samples/landlock/sandboxer.c
@@ -295,6 +295,51 @@ static bool check_ruleset_scope(const char *const env_var,
 
 #define LANDLOCK_ABI_LAST 6
 
+static void print_help(const char *argv0)
+{
+	fprintf(stderr,
+		"usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\" %s "
+		"<cmd> [args]...\n\n",
+		ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
+		ENV_TCP_CONNECT_NAME, ENV_SCOPED_NAME, argv0);
+	fprintf(stderr,
+		"Execute a command in a restricted environment.\n\n");
+	fprintf(stderr,
+		"Environment variables containing paths and ports "
+		"each separated by a colon:\n");
+	fprintf(stderr,
+		"* %s: list of paths allowed to be used in a read-only way.\n",
+		ENV_FS_RO_NAME);
+	fprintf(stderr,
+		"* %s: list of paths allowed to be used in a read-write way.\n\n",
+		ENV_FS_RW_NAME);
+	fprintf(stderr,
+		"Environment variables containing ports are optional "
+		"and could be skipped.\n");
+	fprintf(stderr,
+		"* %s: list of ports allowed to bind (server).\n",
+		ENV_TCP_BIND_NAME);
+	fprintf(stderr,
+		"* %s: list of ports allowed to connect (client).\n",
+		ENV_TCP_CONNECT_NAME);
+	fprintf(stderr, "* %s: list of scoped IPCs.\n",
+		ENV_SCOPED_NAME);
+	fprintf(stderr,
+		"\nexample:\n"
+		"%s=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" "
+		"%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
+		"%s=\"9418\" "
+		"%s=\"80:443\" "
+		"%s=\"a:s\" "
+		"%s bash -i\n\n",
+		ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
+		ENV_TCP_CONNECT_NAME, ENV_SCOPED_NAME, argv0);
+	fprintf(stderr,
+		"This sandboxer can use Landlock features "
+		"up to ABI version %d.\n",
+		LANDLOCK_ABI_LAST);
+}
+
 int main(const int argc, char *const argv[], char *const *const envp)
 {
 	const char *cmd_path;
@@ -313,47 +358,7 @@ int main(const int argc, char *const argv[], char *const *const envp)
 	};
 
 	if (argc < 2) {
-		fprintf(stderr,
-			"usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\" %s "
-			"<cmd> [args]...\n\n",
-			ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
-			ENV_TCP_CONNECT_NAME, ENV_SCOPED_NAME, argv[0]);
-		fprintf(stderr,
-			"Execute a command in a restricted environment.\n\n");
-		fprintf(stderr,
-			"Environment variables containing paths and ports "
-			"each separated by a colon:\n");
-		fprintf(stderr,
-			"* %s: list of paths allowed to be used in a read-only way.\n",
-			ENV_FS_RO_NAME);
-		fprintf(stderr,
-			"* %s: list of paths allowed to be used in a read-write way.\n\n",
-			ENV_FS_RW_NAME);
-		fprintf(stderr,
-			"Environment variables containing ports are optional "
-			"and could be skipped.\n");
-		fprintf(stderr,
-			"* %s: list of ports allowed to bind (server).\n",
-			ENV_TCP_BIND_NAME);
-		fprintf(stderr,
-			"* %s: list of ports allowed to connect (client).\n",
-			ENV_TCP_CONNECT_NAME);
-		fprintf(stderr, "* %s: list of scoped IPCs.\n",
-			ENV_SCOPED_NAME);
-		fprintf(stderr,
-			"\nexample:\n"
-			"%s=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" "
-			"%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
-			"%s=\"9418\" "
-			"%s=\"80:443\" "
-			"%s=\"a:s\" "
-			"%s bash -i\n\n",
-			ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
-			ENV_TCP_CONNECT_NAME, ENV_SCOPED_NAME, argv[0]);
-		fprintf(stderr,
-			"This sandboxer can use Landlock features "
-			"up to ABI version %d.\n",
-			LANDLOCK_ABI_LAST);
+		print_help(argv[0]);
 		return 1;
 	}
 
-- 
2.39.2