int aws_cryptosdk_enc_ctx_serialize()

in source/enc_ctx.c [82:129]

• 40 lines of code
• 13 McCabe index (conditional complexity)

int aws_cryptosdk_enc_ctx_serialize(
    struct aws_allocator *alloc, struct aws_byte_buf *output, const struct aws_hash_table *enc_ctx) {
    AWS_PRECONDITION(AWS_OBJECT_PTR_IS_READABLE(alloc));
    AWS_PRECONDITION(aws_byte_buf_is_valid(output));
    AWS_PRECONDITION(aws_hash_table_is_valid(enc_ctx));

    size_t num_elems = aws_hash_table_get_entry_count(enc_ctx);
    if (num_elems > UINT16_MAX) return aws_raise_error(AWS_CRYPTOSDK_ERR_LIMIT_EXCEEDED);

    size_t length;
    if (aws_cryptosdk_enc_ctx_size(&length, enc_ctx)) return AWS_OP_ERR;
    if (length == 0) return AWS_OP_SUCCESS;  // Empty encryption context
    if (output->capacity < length) return aws_raise_error(AWS_ERROR_SHORT_BUFFER);

    if (!aws_byte_buf_write_be16(output, (uint16_t)num_elems)) {
        aws_byte_buf_clean_up(output);
        return aws_raise_error(AWS_ERROR_SHORT_BUFFER);
    }

    struct aws_array_list elems;
    if (aws_cryptosdk_hash_elems_array_init(alloc, &elems, enc_ctx)) return AWS_OP_ERR;
    aws_array_list_sort(&elems, aws_cryptosdk_compare_hash_elems_by_key_string);

    for (size_t idx = 0; idx < num_elems; ++idx) {
        struct aws_hash_element *elem;
        if (aws_array_list_get_at_ptr(&elems, (void **)&elem, idx)) {
            aws_array_list_clean_up(&elems);
            return AWS_OP_ERR;
        }
        const struct aws_string *key   = (const struct aws_string *)elem->key;
        const struct aws_string *value = (const struct aws_string *)elem->value;
        // Assert that we don't truncate data when we write out the fields.
        // This should have already been assured by aws_aws_cryptosdk_enc_ctx_size()
        AWS_ASSERT(key->len <= UINT16_MAX);
        AWS_ASSERT(value->len <= UINT16_MAX);
        if (!aws_byte_buf_write_be16(output, (uint16_t)key->len)) goto WRITE_ERR;
        if (!aws_byte_buf_write_from_whole_string(output, key)) goto WRITE_ERR;
        if (!aws_byte_buf_write_be16(output, (uint16_t)value->len)) goto WRITE_ERR;
        if (!aws_byte_buf_write_from_whole_string(output, value)) goto WRITE_ERR;
    }
    aws_array_list_clean_up(&elems);
    return AWS_OP_SUCCESS;

WRITE_ERR:
    aws_array_list_clean_up(&elems);
    aws_byte_buf_clean_up(output);
    return aws_raise_error(AWS_ERROR_SHORT_BUFFER);
}