diff options
| -rw-r--r-- | include/linux/string.h | 49 | ||||
| -rw-r--r-- | lib/string_kunit.c | 26 |
2 files changed, 75 insertions, 0 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index 9ba8b4597009..86aa6cd35167 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -423,6 +423,55 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count, } while (0) /** + * memtostr - Copy a possibly non-NUL-term string to a NUL-term string + * @dest: Pointer to destination NUL-terminates string + * @src: Pointer to character array (likely marked as __nonstring) + * + * This is a replacement for strncpy() uses where the source is not + * a NUL-terminated string. + * + * Note that sizes of @dest and @src must be known at compile-time. + */ +#define memtostr(dest, src) do { \ + const size_t _dest_len = __builtin_object_size(dest, 1); \ + const size_t _src_len = __builtin_object_size(src, 1); \ + const size_t _src_chars = strnlen(src, _src_len); \ + const size_t _copy_len = min(_dest_len - 1, _src_chars); \ + \ + BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \ + !__builtin_constant_p(_src_len) || \ + _dest_len == 0 || _dest_len == (size_t)-1 || \ + _src_len == 0 || _src_len == (size_t)-1); \ + memcpy(dest, src, _copy_len); \ + dest[_copy_len] = '\0'; \ +} while (0) + +/** + * memtostr_pad - Copy a possibly non-NUL-term string to a NUL-term string + * with NUL padding in the destination + * @dest: Pointer to destination NUL-terminates string + * @src: Pointer to character array (likely marked as __nonstring) + * + * This is a replacement for strncpy() uses where the source is not + * a NUL-terminated string. + * + * Note that sizes of @dest and @src must be known at compile-time. + */ +#define memtostr_pad(dest, src) do { \ + const size_t _dest_len = __builtin_object_size(dest, 1); \ + const size_t _src_len = __builtin_object_size(src, 1); \ + const size_t _src_chars = strnlen(src, _src_len); \ + const size_t _copy_len = min(_dest_len - 1, _src_chars); \ + \ + BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \ + !__builtin_constant_p(_src_len) || \ + _dest_len == 0 || _dest_len == (size_t)-1 || \ + _src_len == 0 || _src_len == (size_t)-1); \ + memcpy(dest, src, _copy_len); \ + memset(&dest[_copy_len], 0, _dest_len - _copy_len); \ +} while (0) + +/** * memset_after - Set a value after a struct member to the end of a struct * * @obj: Address of target struct instance diff --git a/lib/string_kunit.c b/lib/string_kunit.c index de4eae91403f..fadad46c1b05 100644 --- a/lib/string_kunit.c +++ b/lib/string_kunit.c @@ -524,6 +524,31 @@ static void string_test_strlcat(struct kunit *test) KUNIT_EXPECT_STREQ(test, dest, "fourABE"); } +static void string_test_memtostr(struct kunit *test) +{ + char nonstring[7] = { 'a', 'b', 'c', 'd', 'e', 'f', 'g' }; + char nonstring_small[3] = { 'a', 'b', 'c' }; + char dest[sizeof(nonstring) + 1]; + + /* Copy in a non-NUL-terminated string into exactly right-sized dest. */ + KUNIT_EXPECT_EQ(test, sizeof(dest), sizeof(nonstring) + 1); + memset(dest, 'X', sizeof(dest)); + memtostr(dest, nonstring); + KUNIT_EXPECT_STREQ(test, dest, "abcdefg"); + memset(dest, 'X', sizeof(dest)); + memtostr(dest, nonstring_small); + KUNIT_EXPECT_STREQ(test, dest, "abc"); + KUNIT_EXPECT_EQ(test, dest[7], 'X'); + + memset(dest, 'X', sizeof(dest)); + memtostr_pad(dest, nonstring); + KUNIT_EXPECT_STREQ(test, dest, "abcdefg"); + memset(dest, 'X', sizeof(dest)); + memtostr_pad(dest, nonstring_small); + KUNIT_EXPECT_STREQ(test, dest, "abc"); + KUNIT_EXPECT_EQ(test, dest[7], '\0'); +} + static struct kunit_case string_test_cases[] = { KUNIT_CASE(string_test_memset16), KUNIT_CASE(string_test_memset32), @@ -543,6 +568,7 @@ static struct kunit_case string_test_cases[] = { KUNIT_CASE(string_test_strcat), KUNIT_CASE(string_test_strncat), KUNIT_CASE(string_test_strlcat), + KUNIT_CASE(string_test_memtostr), {} }; |