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