LXR linux/lib/test

   1// SPDX-License-Identifier: GPL-2.0+
   2
   3#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   4
   5#include <linux/string.h>
   6
   7#include "../tools/testing/selftests/kselftest_module.h"
   8
   9/*
  10 * Kernel module for testing 'strscpy' family of functions.
  11 */
  12
  13KSTM_MODULE_GLOBALS();
  14
  15/*
  16 * tc() - Run a specific test case.
  17 * @src: Source string, argument to strscpy_pad()
  18 * @count: Size of destination buffer, argument to strscpy_pad()
  19 * @expected: Expected return value from call to strscpy_pad()
  20 * @terminator: 1 if there should be a terminating null byte 0 otherwise.
  21 * @chars: Number of characters from the src string expected to be
  22 *         written to the dst buffer.
  23 * @pad: Number of pad characters expected (in the tail of dst buffer).
  24 *       (@pad does not include the null terminator byte.)
  25 *
  26 * Calls strscpy_pad() and verifies the return value and state of the
  27 * destination buffer after the call returns.
  28 */
  29static int __init tc(char *src, int count, int expected,
  30                     int chars, int terminator, int pad)
  31{
  32        int nr_bytes_poison;
  33        int max_expected;
  34        int max_count;
  35        int written;
  36        char buf[6];
  37        int index, i;
  38        const char POISON = 'z';
  39
  40        total_tests++;
  41
  42        if (!src) {
  43                pr_err("null source string not supported\n");
  44                return -1;
  45        }
  46
  47        memset(buf, POISON, sizeof(buf));
  48        /* Future proofing test suite, validate args */
  49        max_count = sizeof(buf) - 2; /* Space for null and to verify overflow */
  50        max_expected = count - 1;    /* Space for the null */
  51        if (count > max_count) {
  52                pr_err("count (%d) is too big (%d) ... aborting", count, max_count);
  53                return -1;
  54        }
  55        if (expected > max_expected) {
  56                pr_warn("expected (%d) is bigger than can possibly be returned (%d)",
  57                        expected, max_expected);
  58        }
  59
  60        written = strscpy_pad(buf, src, count);
  61        if ((written) != (expected)) {
  62                pr_err("%d != %d (written, expected)\n", written, expected);
  63                goto fail;
  64        }
  65
  66        if (count && written == -E2BIG) {
  67                if (strncmp(buf, src, count - 1) != 0) {
  68                        pr_err("buffer state invalid for -E2BIG\n");
  69                        goto fail;
  70                }
  71                if (buf[count - 1] != '\0') {
  72                        pr_err("too big string is not null terminated correctly\n");
  73                        goto fail;
  74                }
  75        }
  76
  77        for (i = 0; i < chars; i++) {
  78                if (buf[i] != src[i]) {
  79                        pr_err("buf[i]==%c != src[i]==%c\n", buf[i], src[i]);
  80                        goto fail;
  81                }
  82        }
  83
  84        if (terminator) {
  85                if (buf[count - 1] != '\0') {
  86                        pr_err("string is not null terminated correctly\n");
  87                        goto fail;
  88                }
  89        }
  90
  91        for (i = 0; i < pad; i++) {
  92                index = chars + terminator + i;
  93                if (buf[index] != '\0') {
  94                        pr_err("padding missing at index: %d\n", i);
  95                        goto fail;
  96                }
  97        }
  98
  99        nr_bytes_poison = sizeof(buf) - chars - terminator - pad;
 100        for (i = 0; i < nr_bytes_poison; i++) {
 101                index = sizeof(buf) - 1 - i; /* Check from the end back */
 102                if (buf[index] != POISON) {
 103                        pr_err("poison value missing at index: %d\n", i);
 104                        goto fail;
 105                }
 106        }
 107
 108        return 0;
 109fail:
 110        failed_tests++;
 111        return -1;
 112}
 113
 114static void __init selftest(void)
 115{
 116        /*
 117         * tc() uses a destination buffer of size 6 and needs at
 118         * least 2 characters spare (one for null and one to check for
 119         * overflow).  This means we should only call tc() with
 120         * strings up to a maximum of 4 characters long and 'count'
 121         * should not exceed 4.  To test with longer strings increase
 122         * the buffer size in tc().
 123         */
 124
 125        /* tc(src, count, expected, chars, terminator, pad) */
 126        KSTM_CHECK_ZERO(tc("a", 0, -E2BIG, 0, 0, 0));
 127        KSTM_CHECK_ZERO(tc("", 0, -E2BIG, 0, 0, 0));
 128
 129        KSTM_CHECK_ZERO(tc("a", 1, -E2BIG, 0, 1, 0));
 130        KSTM_CHECK_ZERO(tc("", 1, 0, 0, 1, 0));
 131
 132        KSTM_CHECK_ZERO(tc("ab", 2, -E2BIG, 1, 1, 0));
 133        KSTM_CHECK_ZERO(tc("a", 2, 1, 1, 1, 0));
 134        KSTM_CHECK_ZERO(tc("", 2, 0, 0, 1, 1));
 135
 136        KSTM_CHECK_ZERO(tc("abc", 3, -E2BIG, 2, 1, 0));
 137        KSTM_CHECK_ZERO(tc("ab", 3, 2, 2, 1, 0));
 138        KSTM_CHECK_ZERO(tc("a", 3, 1, 1, 1, 1));
 139        KSTM_CHECK_ZERO(tc("", 3, 0, 0, 1, 2));
 140
 141        KSTM_CHECK_ZERO(tc("abcd", 4, -E2BIG, 3, 1, 0));
 142        KSTM_CHECK_ZERO(tc("abc", 4, 3, 3, 1, 0));
 143        KSTM_CHECK_ZERO(tc("ab", 4, 2, 2, 1, 1));
 144        KSTM_CHECK_ZERO(tc("a", 4, 1, 1, 1, 2));
 145        KSTM_CHECK_ZERO(tc("", 4, 0, 0, 1, 3));
 146}
 147
 148KSTM_MODULE_LOADERS(test_strscpy);
 149MODULE_AUTHOR("Tobin C. Harding <tobin@kernel.org>");
 150MODULE_LICENSE("GPL");
 151