[LTP] [PATCH] lib: tst_kconfig: Add runtime checks

[Cyril Hrubis]

So far for CONFIG_*_NS.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
---
 lib/newlib_tests/test_kconfig.c |  1 +
 lib/tst_kconfig.c               | 35 +++++++++++++++++++++++++++++++++
 lib/tst_ns_checks.h             | 32 ++++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+)
 create mode 100644 lib/tst_ns_checks.h

diff --git a/lib/newlib_tests/test_kconfig.c b/lib/newlib_tests/test_kconfig.c
index cea36b5ee..ed2c4610a 100644
--- a/lib/newlib_tests/test_kconfig.c
+++ b/lib/newlib_tests/test_kconfig.c
@@ -18,6 +18,7 @@ static const char *kconfigs[] = {
 	"CONFIG_MMU & CONFIG_EXT4_FS=m",
 	"CONFIG_EXT4_FS=m | CONFIG_MMU",
 	"CONFIG_DEFAULT_HOSTNAME=\"(none)\"",
+	"CONFIG_USER_NS",
 	NULL
 };
 
diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
index 9bcd57721..8d0f8ae3a 100644
--- a/lib/tst_kconfig.c
+++ b/lib/tst_kconfig.c
@@ -16,6 +16,8 @@
 #include "tst_bool_expr.h"
 #include "tst_safe_stdio.h"
 
+#include "tst_ns_checks.h"
+
 static int kconfig_skip_check(void)
 {
 	char *skipped = getenv("KCONFIG_SKIP_CHECK");
@@ -110,6 +112,37 @@ static void close_kconfig(FILE *fp)
 		fclose(fp);
 }
 
+static struct runtime_check {
+	const char *config;
+	bool (*runtime_check)(void);
+} runtime_checks[] = {
+	{"CONFIG_USER_NS", tst_user_ns_enabled},
+	{"CONFIG_NET_NS", tst_net_ns_enabled},
+	{"CONFIG_PID_NS", tst_pid_ns_enabled},
+	{"CONFIG_MNT_NS", tst_mnt_ns_enabled},
+	{"CONFIG_IPC_NS", tst_ipc_ns_enabled},
+	{}
+};
+
+static void runtime_check(struct tst_kconfig_var *var)
+{
+	size_t i;
+
+	for (i = 0; runtime_checks[i].config; i++) {
+		if (strcmp(runtime_checks[i].config, var->id))
+			continue;
+
+		tst_res(TDEBUG, "Running runtime check for '%s'", var->id);
+
+		if (!runtime_checks[i].runtime_check()) {
+			tst_res(TINFO,
+				"%s=%c present but disabled at runtime",
+				var->id, var->choice);
+			var->choice = 'n';
+		}
+	}
+}
+
 static inline int kconfig_parse_line(const char *line,
                                      struct tst_kconfig_var *vars,
                                      unsigned int vars_len)
@@ -183,9 +216,11 @@ out:
 			switch (val[0]) {
 			case 'y':
 				vars[i].choice = 'y';
+				runtime_check(&vars[i]);
 				return 1;
 			case 'm':
 				vars[i].choice = 'm';
+				runtime_check(&vars[i]);
 				return 1;
 			}
 		}
diff --git a/lib/tst_ns_checks.h b/lib/tst_ns_checks.h
new file mode 100644
index 000000000..743d3d09d
--- /dev/null
+++ b/lib/tst_ns_checks.h
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 Cyril Hrubis <chrubis@suse.cz>
+ */
+
+#include <unistd.h>
+#include <stdbool.h>
+
+static inline bool tst_user_ns_enabled(void)
+{
+	return access("/proc/self/ns/user", F_OK) == 0;
+}
+
+static inline bool tst_net_ns_enabled(void)
+{
+	return access("/proc/self/ns/net", F_OK) == 0;
+}
+
+static inline bool tst_pid_ns_enabled(void)
+{
+	return access("/proc/self/ns/pid", F_OK) == 0;
+}
+
+static inline bool tst_mnt_ns_enabled(void)
+{
+	return access("/proc/self/ns/mnt", F_OK) == 0;
+}
+
+static inline bool tst_ipc_ns_enabled(void)
+{
+	return access("/proc/self/ns/ipc", F_OK) == 0;
+}
-- 
2.52.0