// SPDX-License-Identifier: GPL-2.0+
/*
* Kernel module for testing 'strscpy' family of functions.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <kunit/test.h>
#include <linux/string.h>
/*
* tc() - Run a specific test case.
* @src: Source string, argument to strscpy_pad()
* @count: Size of destination buffer, argument to strscpy_pad()
* @expected: Expected return value from call to strscpy_pad()
* @terminator: 1 if there should be a terminating null byte 0 otherwise.
* @chars: Number of characters from the src string expected to be
* written to the dst buffer.
* @pad: Number of pad characters expected (in the tail of dst buffer).
* (@pad does not include the null terminator byte.)
*
* Calls strscpy_pad() and verifies the return value and state of the
* destination buffer after the call returns.
*/
static void tc(struct kunit *test, char *src, int count, int expected,
int chars, int terminator, int pad)
{
int nr_bytes_poison;
int max_expected;
int max_count;
int written;
char buf[6];
int index, i;
const char POISON = 'z';
KUNIT_ASSERT_TRUE_MSG(test, src != NULL,
"null source string not supported");
memset(buf, POISON, sizeof(buf));
/* Future proofing test suite, validate args */
max_count = sizeof(buf) - 2; /* Space for null and to verify overflow */
max_expected = count - 1; /* Space for the null */
KUNIT_ASSERT_LE_MSG(test, count, max_count,
"count (%d) is too big (%d) ... aborting", count, max_count);
KUNIT_EXPECT_LE_MSG(test, expected, max_expected,
"expected (%d) is bigger than can possibly be returned (%d)",
expected, max_expected);
written = strscpy_pad(buf, src, count);
KUNIT_ASSERT_EQ(test, written, expected);
if (count && written == -E2BIG) {
KUNIT_ASSERT_EQ_MSG(test, 0, strncmp(buf, src, count - 1),
"buffer state invalid for -E2BIG");
KUNIT_ASSERT_EQ_MSG(test, buf[count - 1], '\0',
"too big string is not null terminated correctly");
}
for (i = 0; i < chars; i++)
KUNIT_ASSERT_EQ_MSG(test, buf[i], src[i],
"buf[i]==%c != src[i]==%c", buf[i], src[i]);
if (terminator)
KUNIT_ASSERT_EQ_MSG(test, buf[count - 1], '\0',
"string is not null terminated correctly");
for (i = 0; i < pad; i++) {
index = chars + terminator + i;
KUNIT_ASSERT_EQ_MSG(test, buf[index], '\0',
"padding missing at index: %d", i);
}
nr_bytes_poison = sizeof(buf) - chars - terminator - pad;
for (i = 0; i < nr_bytes_poison; i++) {
index = sizeof(buf) - 1 - i; /* Check from the end back */
KUNIT_ASSERT_EQ_MSG(test, buf[index], POISON,
"poison value missing at index: %d", i);
}
}
static void strscpy_test(struct kunit *test)
{
char dest[8];
/*
* tc() uses a destination buffer of size 6 and needs at
* least 2 characters spare (one for null and one to check for
* overflow). This means we should only call tc() with
* strings up to a maximum of 4 characters long and 'count'
* should not exceed 4. To test with longer strings increase
* the buffer size in tc().
*/
/* tc(test, src, count, expected, chars, terminator, pad) */
tc(test, "a", 0, -E2BIG, 0, 0, 0);
tc(test, "", 0, -E2BIG, 0, 0, 0);
tc(test, "a", 1, -E2BIG, 0, 1, 0);
tc(test, "", 1, 0, 0, 1, 0);
tc(test, "ab", 2, -E2BIG, 1, 1, 0);
tc(test, "a", 2, 1, 1, 1, 0);
tc(test, "", 2, 0, 0, 1, 1);
tc(test, "abc", 3, -E2BIG, 2, 1, 0);
tc(test, "ab", 3, 2, 2, 1, 0);
tc(test, "a", 3, 1, 1, 1, 1);
tc(test, "", 3, 0, 0, 1, 2);
tc(test, "abcd", 4, -E2BIG, 3, 1, 0);
tc(test, "abc", 4, 3, 3, 1, 0);
tc(test, "ab", 4, 2, 2, 1, 1);
tc(test, "a", 4, 1, 1, 1, 2);
tc(test, "", 4, 0, 0, 1, 3);
/* Compile-time-known source strings. */
KUNIT_EXPECT_EQ(test, strscpy(dest, "", ARRAY_SIZE(dest)), 0);
KUNIT_EXPECT_EQ(test, strscpy(dest, "", 3), 0);
KUNIT_EXPECT_EQ(test, strscpy(dest, "", 1), 0);
KUNIT_EXPECT_EQ(test, strscpy(dest, "", 0), -E2BIG);
KUNIT_EXPECT_EQ(test, strscpy(dest, "Fixed", ARRAY_SIZE(dest)), 5);
KUNIT_EXPECT_EQ(test, strscpy(dest, "Fixed", 3), -E2BIG);
KUNIT_EXPECT_EQ(test, strscpy(dest, "Fixed", 1), -E2BIG);
KUNIT_EXPECT_EQ(test, strscpy(dest, "Fixed", 0), -E2BIG);
KUNIT_EXPECT_EQ(test, strscpy(dest, "This is too long", ARRAY_SIZE(dest)), -E2BIG);
}
static struct kunit_case strscpy_test_cases[] = {
KUNIT_CASE(strscpy_test),
{}
};
static struct kunit_suite strscpy_test_suite = {
.name = "strscpy",
.test_cases = strscpy_test_cases,
};
kunit_test_suite(strscpy_test_suite);
MODULE_AUTHOR("Tobin C. Harding <tobin@kernel.org>");
MODULE_LICENSE("GPL");
