[LTP] [PATCH v2 09/18] testcases/lib: Implement tst_cgctl binary

[Luke Nowakowski-Krijger]

Implement a binary utility that creates an interface to make calls to
the cgroup C API.

This will effectively allow shell scripts to make calls to the cgroup C
api.

Signed-off-by: Luke Nowakowski-Krijger <luke.nowakowskikrijger@canonical.com>
---
v2: Add license identifier and copyright.
Reformat with tabs instead of spaces.
Add help format message and help function.
Add error gotos to streamline error messaging.

 testcases/lib/Makefile    |  2 +-
 testcases/lib/tst_cgctl.c | 87 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 testcases/lib/tst_cgctl.c

diff --git a/testcases/lib/Makefile b/testcases/lib/Makefile
index f2de0c832..f4f8c8524 100644
--- a/testcases/lib/Makefile
+++ b/testcases/lib/Makefile
@@ -12,6 +12,6 @@ MAKE_TARGETS		:= tst_sleep tst_random tst_checkpoint tst_rod tst_kvcmp\
 			   tst_device tst_net_iface_prefix tst_net_ip_prefix tst_net_vars\
 			   tst_getconf tst_supported_fs tst_check_drivers tst_get_unused_port\
 			   tst_get_median tst_hexdump tst_get_free_pids tst_timeout_kill\
-			   tst_check_kconfigs
+			   tst_check_kconfigs tst_cgctl
 
 include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/lib/tst_cgctl.c b/testcases/lib/tst_cgctl.c
new file mode 100644
index 000000000..4f4fe8542
--- /dev/null
+++ b/testcases/lib/tst_cgctl.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2022 Canonical Ltd.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+#include "tst_cgroup.h"
+
+#define USAGE "Usage: tst_cgctl require [controller] [test_pid]\n\
+	\t cleanup [config (output of tst_cg_print_config)]\n\
+	\t print\n\
+	\t help\n"
+
+static int cgctl_require(const char *ctrl, int test_pid)
+{
+	struct tst_cg_opts opts;
+
+	memset(&opts, 0, sizeof(opts));
+	opts.test_pid = test_pid;
+
+	tst_cg_require(ctrl, &opts);
+	tst_cg_print_config();
+
+	return 0;
+}
+
+static int cgctl_cleanup(const char *const config)
+{
+	tst_cg_scan();
+	tst_cg_load_config(config);
+	tst_cg_cleanup();
+
+	return 0;
+}
+
+static int cgctl_print(void)
+{
+	tst_cg_scan();
+	tst_cg_print_config();
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int test_pid;
+	const char *cmd_name = argv[1];
+
+	if (argc < 2)
+		goto error;
+
+	if (!strcmp(cmd_name, "require")) {
+		if (argc != 4)
+			goto arg_num_error;
+		test_pid = atoi(argv[3]);
+		if (!test_pid) {
+			fprintf(stderr, "tst_cgctl: Invalid test_pid '%s' given\n",
+				argv[3]);
+			goto error;
+		}
+		return cgctl_require(argv[2], test_pid);
+	} else if (!strcmp(cmd_name, "cleanup")) {
+		if (argc != 3)
+			goto arg_num_error;
+		return cgctl_cleanup(argv[2]);
+	} else if (!strcmp(cmd_name, "print")) {
+		return cgctl_print();
+	} else if (!strcmp(cmd_name, "help")) {
+		printf(USAGE);
+		return 0;
+	}
+
+	fprintf(stderr, "tst_cgctl: Unknown command '%s' given\n", cmd_name);
+	goto error;
+
+arg_num_error:
+	fprintf(stderr,
+		"tst_cgctl: Invalid number of arguments given for command '%s'\n",
+		cmd_name);
+error:
+	fprintf(stderr, USAGE);
+	return 1;
+}
-- 
2.34.1