如果没有发生缓冲区溢出，返回值始终是组合字符串的长度；这使得检测缓冲区溢出真正变得容易了。

The return value is always the size of the combined string if no buffer overflow occurred; this makes it really easy to detect an overflow.

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如果参数为NULL，则openssl会将字符串写入到一个长度为256字节的静态缓冲区中，并返回指向该缓冲区的指针。

If this parameter is NULL, OpenSSL writes the string to a static buffer that is 256 bytes in length, and returns a pointer to that buffer.

youdao

如 SQL 标准中所述，此函数返回输入字符串的八位字节长度或字节长度。

This function, as mentioned in SQL standard, returns the length of the input string in octets or bytes.

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