如何找到用C解码的base64数据的大小

Question

我有在解码二进制数据的base64编码数据的功能，但我不知道如何找到解码数据的长度。我用BIO功能OpenSSL中。

unsigned char *unbase64(unsigned char *input, int length)
{
    BIO *b64, *bmem;

    unsigned char *buffer = (unsigned char *)malloc(length);
    memset(buffer, 0, length);

    b64 = BIO_new(BIO_f_base64());
    bmem = BIO_new_mem_buf(input, length);
    bmem = BIO_push(b64, bmem);

    BIO_read(bmem, buffer, length);

    BIO_free_all(bmem);

    return buffer;
}

Answer 1

BIO_READ将返回读取的字节数。您应该检查返回值贯穿始终，反正。