smb/client: introduce KUnit test to check ntstatus_to_dos_map search

Check whether all elements can be correctly found in the array.

Introduce CONFIG_SMB1_KUNIT_TESTS for smb1maperror_test.ko since
smb1maperror.o is only built when CONFIG_CIFS_ALLOW_INSECURE_LEGACY
is enabled.

We are going to define 3 functions to check the search results, introduce
the macro DEFINE_CHECK_SEARCH_FUNC() to reduce duplicate code.

Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: tangyouling

fs/smb/client/Kconfig

@@ -217,4 +217,15 @@ config CIFS_COMPRESSION
 	  Say Y here if you want SMB traffic to be compressed.
 	  If unsure, say N.
 
+config SMB1_KUNIT_TESTS
+	tristate "KUnit tests for SMB1"
+	depends on SMB_KUNIT_TESTS && CIFS_ALLOW_INSECURE_LEGACY
+	default SMB_KUNIT_TESTS
+	help
+	  This builds the SMB1-specific KUnit tests.
+
+	  These tests are only enabled when legacy insecure SMB1 support
+	  (CIFS_ALLOW_INSECURE_LEGACY) is enabled.
+
+	  If unsure, say N.
 endif

fs/smb/client/Makefile

@@ -71,6 +71,7 @@ $(obj)/smb2maperror.o: $(obj)/smb2_mapping_table.c
 quiet_cmd_gen_smb2_mapping = GEN     $@
       cmd_gen_smb2_mapping = perl $(src)/gen_smb2_mapping $< $@
 
+obj-$(CONFIG_SMB1_KUNIT_TESTS) += smb1maperror_test.o
 obj-$(CONFIG_SMB_KUNIT_TESTS) += smb2maperror_test.o
 
 # Let Kbuild handle tracking and cleaning

fs/smb/client/smb1maperror.c

@@ -288,3 +288,22 @@ int __init smb1_init_maperror(void)
 
 	return rc;
 }
+
+#if IS_ENABLED(CONFIG_SMB1_KUNIT_TESTS)
+#define EXPORT_SYMBOL_FOR_SMB_TEST(sym) \
+	EXPORT_SYMBOL_FOR_MODULES(sym, "smb1maperror_test")
+
+const struct ntstatus_to_dos_err *
+search_ntstatus_to_dos_map_test(__u32 ntstatus)
+{
+	return search_ntstatus_to_dos_map(ntstatus);
+}
+EXPORT_SYMBOL_FOR_SMB_TEST(search_ntstatus_to_dos_map_test);
+
+const struct ntstatus_to_dos_err *
+ntstatus_to_dos_map_test = ntstatus_to_dos_map;
+EXPORT_SYMBOL_FOR_SMB_TEST(ntstatus_to_dos_map_test);
+
+unsigned int ntstatus_to_dos_num = ARRAY_SIZE(ntstatus_to_dos_map);
+EXPORT_SYMBOL_FOR_SMB_TEST(ntstatus_to_dos_num);
+#endif

fs/smb/client/smb1maperror_test.c

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ *   KUnit tests of SMB1 maperror
+ *
+ *   Copyright (C) 2026 KylinSoft Co., Ltd. All rights reserved.
+ *   Author(s): Youling Tang <tangyouling@kylinos.cn>
+ *              ChenXiaoSong <chenxiaosong@kylinos.cn>
+ *
+ */
+
+#include <kunit/test.h>
+#include "smb1proto.h"
+#include "nterr.h"
+
+#define DEFINE_CHECK_SEARCH_FUNC(__struct_name, __field,		\
+				 __array, __num)			\
+static void check_search_ ## __array(struct kunit *test)		\
+{									\
+	unsigned int i;							\
+	const struct __struct_name *expect, *result;			\
+									\
+	for (i = 0; i < __num; i++) {					\
+		expect = &__array ## _test[i];				\
+		result = search_ ## __array ## _test(expect->__field);	\
+		KUNIT_ASSERT_NOT_NULL(test, result);			\
+		test_cmp_ ## __struct_name(test, expect, result);	\
+	}								\
+}
+
+static void
+test_cmp_ntstatus_to_dos_err(struct kunit *test,
+			     const struct ntstatus_to_dos_err *expect,
+			     const struct ntstatus_to_dos_err *result)
+{
+	KUNIT_EXPECT_EQ(test, expect->dos_class, result->dos_class);
+	KUNIT_EXPECT_EQ(test, expect->dos_code, result->dos_code);
+	KUNIT_EXPECT_EQ(test, expect->ntstatus, result->ntstatus);
+	KUNIT_EXPECT_STREQ(test, expect->nt_errstr, result->nt_errstr);
+}
+
+/* check_search_ntstatus_to_dos_map */
+DEFINE_CHECK_SEARCH_FUNC(ntstatus_to_dos_err, ntstatus, ntstatus_to_dos_map,
+			 ntstatus_to_dos_num);
+
+static struct kunit_case maperror_test_cases[] = {
+	KUNIT_CASE(check_search_ntstatus_to_dos_map),
+	{}
+};
+
+static struct kunit_suite maperror_suite = {
+	.name = "smb1_maperror",
+	.test_cases = maperror_test_cases,
+};
+
+kunit_test_suite(maperror_suite);
+
+MODULE_LICENSE("GPL");

fs/smb/client/smb1proto.h

@@ -237,6 +237,12 @@ int map_smb_to_linux_error(char *buf, bool logErr);
 int smb1_init_maperror(void);
 int map_and_check_smb_error(struct TCP_Server_Info *server,
 			    struct mid_q_entry *mid, bool logErr);
+#if IS_ENABLED(CONFIG_SMB1_KUNIT_TESTS)
+extern const struct ntstatus_to_dos_err *ntstatus_to_dos_map_test;
+extern unsigned int ntstatus_to_dos_num;
+const struct ntstatus_to_dos_err *
+search_ntstatus_to_dos_map_test(__u32 ntstatus);
+#endif
 
 /*
  * smb1misc.c