Comment by asveikau

1 day ago

A bit of a code review (some details from the patch removed for clarity):

   +       register int i;
           q = password;
   -       while((*q = getchar()) != '\n')
   +       i = 0;
   +       while((*q = getchar()) != '\n') {
   +               if (++i >= sizeof(password))
   +                       goto error;

You don't actually need i here. i is the same as (q - password). It would be idiomatic C to simply rewrite the loop condition as: while (q < password+sizeof(password) && (*q = getchar()) != '\n'). To preserve your "goto error;" part, maybe you could do the overflow check when null terminating outside the loop.

2 comments

asveikau

shakna 1 day ago

Isn't sizeof only standardised in C89? Wouldn't shock me if this form needs to be an rvalue.

The author did try pointer arithmetic:

> I initially attempted a fix using pointer arithmetic, but the 1973 C compiler didn’t like it, while it didn’t refuse the syntax, the code had no effect.

asveikau 1 day ago

This surprised me too. The snippet I was quoting from was already using sizeof, though.
I missed the blurb about pointer arithmetic. Would be interesting to go into detail about what "had no effect" means.