What every C Programmer should know about undefined behavior #2/3

For your last point, basically it comes down to "if there might be a \0 in valid input for this function, even though it may be a byte[], it is not a string."

So you use memchr() instead of strchr().

Or you use C++, and call it a string instead of a byte[]. (and use the actual C++ string-manipulation functions, not strchr - g++ warns about (byte[])string as being an invalid cast nowadays anyway though) :)