test_strscpy.c
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// SPDX-License-Identifier: GPL-2.0+
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/string.h>
#include "../tools/testing/selftests/kselftest_module.h"
/*
* Kernel module for testing 'strscpy' family of functions.
*/
KSTM_MODULE_GLOBALS();
/*
* 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 int __init tc(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';
total_tests++;
if (!src) {
pr_err("null source string not supported\n");
return -1;
}
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 */
if (count > max_count) {
pr_err("count (%d) is too big (%d) ... aborting", count, max_count);
return -1;
}
if (expected > max_expected) {
pr_warn("expected (%d) is bigger than can possibly be returned (%d)",
expected, max_expected);
}
written = strscpy_pad(buf, src, count);
if ((written) != (expected)) {
pr_err("%d != %d (written, expected)\n", written, expected);
goto fail;
}
if (count && written == -E2BIG) {
if (strncmp(buf, src, count - 1) != 0) {
pr_err("buffer state invalid for -E2BIG\n");
goto fail;
}
if (buf[count - 1] != '\0') {
pr_err("too big string is not null terminated correctly\n");
goto fail;
}
}
for (i = 0; i < chars; i++) {
if (buf[i] != src[i]) {
pr_err("buf[i]==%c != src[i]==%c\n", buf[i], src[i]);
goto fail;
}
}
if (terminator) {
if (buf[count - 1] != '\0') {
pr_err("string is not null terminated correctly\n");
goto fail;
}
}
for (i = 0; i < pad; i++) {
index = chars + terminator + i;
if (buf[index] != '\0') {
pr_err("padding missing at index: %d\n", i);
goto fail;
}
}
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 */
if (buf[index] != POISON) {
pr_err("poison value missing at index: %d\n", i);
goto fail;
}
}
return 0;
fail:
failed_tests++;
return -1;
}
static void __init selftest(void)
{
/*
* 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(src, count, expected, chars, terminator, pad) */
KSTM_CHECK_ZERO(tc("a", 0, -E2BIG, 0, 0, 0));
KSTM_CHECK_ZERO(tc("", 0, -E2BIG, 0, 0, 0));
KSTM_CHECK_ZERO(tc("a", 1, -E2BIG, 0, 1, 0));
KSTM_CHECK_ZERO(tc("", 1, 0, 0, 1, 0));
KSTM_CHECK_ZERO(tc("ab", 2, -E2BIG, 1, 1, 0));
KSTM_CHECK_ZERO(tc("a", 2, 1, 1, 1, 0));
KSTM_CHECK_ZERO(tc("", 2, 0, 0, 1, 1));
KSTM_CHECK_ZERO(tc("abc", 3, -E2BIG, 2, 1, 0));
KSTM_CHECK_ZERO(tc("ab", 3, 2, 2, 1, 0));
KSTM_CHECK_ZERO(tc("a", 3, 1, 1, 1, 1));
KSTM_CHECK_ZERO(tc("", 3, 0, 0, 1, 2));
KSTM_CHECK_ZERO(tc("abcd", 4, -E2BIG, 3, 1, 0));
KSTM_CHECK_ZERO(tc("abc", 4, 3, 3, 1, 0));
KSTM_CHECK_ZERO(tc("ab", 4, 2, 2, 1, 1));
KSTM_CHECK_ZERO(tc("a", 4, 1, 1, 1, 2));
KSTM_CHECK_ZERO(tc("", 4, 0, 0, 1, 3));
}
KSTM_MODULE_LOADERS(test_strscpy);
MODULE_AUTHOR("Tobin C. Harding <tobin@kernel.org>");
MODULE_LICENSE("GPL");