Retrieves string of given length from user space
user_string_n2:string(addr:long,n:long,err_msg:string)
addr
the user space address to retrieve the string from
n
the maximum length of the string (if not null terminated)
err_msg
the error message to return when data isn't available
Returns the C string of a maximum given length from a given user space address. Returns the given error message string on the rare cases when userspace data is not accessible at the given address.