Appends @len bytes of @val to @string. Because @len is provided, @val may contain embedded nuls and need not be nul-terminated.
Since this function does not stop at nul bytes, it is the caller's responsibility to ensure that @val has at least @len addressable bytes.
bytes to append
number of bytes of @val to use
Return: @string
See Implementation
Appends @len bytes of @val to @string. Because @len is provided, @val may contain embedded nuls and need not be nul-terminated.
Since this function does not stop at nul bytes, it is the caller's responsibility to ensure that @val has at least @len addressable bytes.