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Merge pull request #260 from PJK/zero-len-strings
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Fix cbor_serialized_size for zero-len strings
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@PJK
PJK authored Dec 30, 2022
2 parents d9e3d17 + 2393275 commit cbea271
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Showing 3 changed files with 120 additions and 6 deletions.
1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ Template:

Next
---------------------
- [Fix a regression in `cbor_serialize_alloc` that caused serialization of zero-length strings and bytestrings or byte/strings with zero-length chunks to fail](https://github.com/PJK/libcbor/pull/260) (discovered by [martelletto](https://github.com/martelletto))

0.10.0 (2022-12-29)
---------------------
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18 changes: 12 additions & 6 deletions src/cbor/serialization.c
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Expand Up @@ -74,11 +74,16 @@ size_t cbor_serialized_size(const cbor_item_t *item) {
case CBOR_INT_64:
return 9;
}
// Note: We do not _cbor_safe_signaling_add zero-length definite strings,
// they would cause zeroes to propagate. All other items are at least one
// byte.
case CBOR_TYPE_BYTESTRING: {
if (cbor_bytestring_is_definite(item)) {
return _cbor_safe_signaling_add(
_cbor_encoded_header_size(cbor_bytestring_length(item)),
cbor_bytestring_length(item));
size_t header_size =
_cbor_encoded_header_size(cbor_bytestring_length(item));
if (cbor_bytestring_length(item) == 0) return header_size;
return _cbor_safe_signaling_add(header_size,
cbor_bytestring_length(item));
}
size_t indef_bytestring_size = 2; // Leading byte + break
cbor_item_t **chunks = cbor_bytestring_chunks_handle(item);
Expand All @@ -90,9 +95,10 @@ size_t cbor_serialized_size(const cbor_item_t *item) {
}
case CBOR_TYPE_STRING: {
if (cbor_string_is_definite(item)) {
return _cbor_safe_signaling_add(
_cbor_encoded_header_size(cbor_string_length(item)),
cbor_string_length(item));
size_t header_size =
_cbor_encoded_header_size(cbor_string_length(item));
if (cbor_string_length(item) == 0) return header_size;
return _cbor_safe_signaling_add(header_size, cbor_string_length(item));
}
size_t indef_string_size = 2; // Leading byte + break
cbor_item_t **chunks = cbor_string_chunks_handle(item);
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107 changes: 107 additions & 0 deletions test/cbor_serialize_test.c
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Expand Up @@ -505,6 +505,7 @@ static void test_auto_serialize_too_large(void **_CBOR_UNUSED(_state)) {

// Pretend the chunk is huge
chunk->metadata.string_metadata.length = SIZE_MAX;
assert_true(SIZE_MAX + 2 == 1);
assert_int_equal(cbor_serialized_size(item), 0);
unsigned char *output;
size_t output_size;
Expand All @@ -531,6 +532,104 @@ static void test_auto_serialize_alloc_fail(void **_CBOR_UNUSED(_state)) {
cbor_decref(&item);
}

static void test_auto_serialize_zero_len_bytestring(
void **_CBOR_UNUSED(_state)) {
cbor_item_t *item = cbor_build_bytestring((cbor_data) "", 0);

unsigned char *output;
assert_int_equal(cbor_serialize_alloc(item, &output, NULL), 1);
assert_memory_equal(output, ((unsigned char[]){0x40}), 1);
assert_int_equal(cbor_serialized_size(item), 1);
cbor_decref(&item);
_cbor_free(output);
}

static void test_auto_serialize_zero_len_string(void **_CBOR_UNUSED(_state)) {
cbor_item_t *item = cbor_build_string("");

unsigned char *output;
assert_int_equal(cbor_serialize_alloc(item, &output, NULL), 1);
assert_memory_equal(output, ((unsigned char[]){0x60}), 1);
assert_int_equal(cbor_serialized_size(item), 1);
cbor_decref(&item);
_cbor_free(output);
}

static void test_auto_serialize_zero_len_bytestring_chunk(
void **_CBOR_UNUSED(_state)) {
cbor_item_t *item = cbor_new_indefinite_bytestring();

assert_true(cbor_bytestring_add_chunk(
item, cbor_move(cbor_build_bytestring((cbor_data) "", 0))));

unsigned char *output;
assert_int_equal(cbor_serialize_alloc(item, &output, NULL), 3);
assert_memory_equal(output, ((unsigned char[]){0x5f, 0x40, 0xff}), 3);
assert_int_equal(cbor_serialized_size(item), 3);
cbor_decref(&item);
_cbor_free(output);
}

static void test_auto_serialize_zero_len_string_chunk(
void **_CBOR_UNUSED(_state)) {
cbor_item_t *item = cbor_new_indefinite_string();

assert_true(cbor_string_add_chunk(item, cbor_move(cbor_build_string(""))));

unsigned char *output;
assert_int_equal(cbor_serialize_alloc(item, &output, NULL), 3);
assert_memory_equal(output, ((unsigned char[]){0x7f, 0x60, 0xff}), 3);
assert_int_equal(cbor_serialized_size(item), 3);
cbor_decref(&item);
_cbor_free(output);
}

static void test_auto_serialize_zero_len_array(void **_CBOR_UNUSED(_state)) {
cbor_item_t *item = cbor_new_definite_array(0);

unsigned char *output;
assert_int_equal(cbor_serialize_alloc(item, &output, NULL), 1);
assert_memory_equal(output, ((unsigned char[]){0x80}), 1);
assert_int_equal(cbor_serialized_size(item), 1);
cbor_decref(&item);
_cbor_free(output);
}

static void test_auto_serialize_zero_len_indef_array(
void **_CBOR_UNUSED(_state)) {
cbor_item_t *item = cbor_new_indefinite_array();

unsigned char *output;
assert_int_equal(cbor_serialize_alloc(item, &output, NULL), 2);
assert_memory_equal(output, ((unsigned char[]){0x9f, 0xff}), 2);
assert_int_equal(cbor_serialized_size(item), 2);
cbor_decref(&item);
_cbor_free(output);
}

static void test_auto_serialize_zero_len_map(void **_CBOR_UNUSED(_state)) {
cbor_item_t *item = cbor_new_definite_map(0);

unsigned char *output;
assert_int_equal(cbor_serialize_alloc(item, &output, NULL), 1);
assert_memory_equal(output, ((unsigned char[]){0xa0}), 1);
assert_int_equal(cbor_serialized_size(item), 1);
cbor_decref(&item);
_cbor_free(output);
}

static void test_auto_serialize_zero_len_indef_map(
void **_CBOR_UNUSED(_state)) {
cbor_item_t *item = cbor_new_indefinite_map();

unsigned char *output;
assert_int_equal(cbor_serialize_alloc(item, &output, NULL), 2);
assert_memory_equal(output, ((unsigned char[]){0xbf, 0xff}), 2);
assert_int_equal(cbor_serialized_size(item), 2);
cbor_decref(&item);
_cbor_free(output);
}

int main(void) {
const struct CMUnitTest tests[] = {
cmocka_unit_test(test_serialize_uint8_embed),
Expand Down Expand Up @@ -570,6 +669,14 @@ int main(void) {
cmocka_unit_test(test_auto_serialize_no_size),
cmocka_unit_test(test_auto_serialize_too_large),
cmocka_unit_test(test_auto_serialize_alloc_fail),
cmocka_unit_test(test_auto_serialize_zero_len_bytestring),
cmocka_unit_test(test_auto_serialize_zero_len_string),
cmocka_unit_test(test_auto_serialize_zero_len_bytestring_chunk),
cmocka_unit_test(test_auto_serialize_zero_len_string_chunk),
cmocka_unit_test(test_auto_serialize_zero_len_array),
cmocka_unit_test(test_auto_serialize_zero_len_indef_array),
cmocka_unit_test(test_auto_serialize_zero_len_map),
cmocka_unit_test(test_auto_serialize_zero_len_indef_map),
};
return cmocka_run_group_tests(tests, NULL, NULL);
}

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