Thread: Any point to strnlen?

From MSDN

'strnlen is not a replacement for strlen; strnlen is intended to be used only to calculate the size of incoming untrusted data in a buffer of known size—for example, a network packet. strnlen calculates the length but doesn't walk past the end of the buffer if the string is unterminated.'


I came upon strnlen in some source, never seen it before, seems that it's used in Unix and MS have their own version though not standard C/C++.


So it checks a string against a buffer of known size and if > buffer returns string up to max buffer size.
So don't see how this is needed, terminated or not strlen is less work and does same thing?

Code:

size_t buffer = 1000;


if (strlen(str) > buffer){
   return -1
}

as even if you used strnlen you would still have to at least say

Code:

size_t buffer = 1000;


unsigned int i_str = strnlen(str, buffer);


if i_str == buffer{
   return -1
}