On Tue, Aug 16, 2022 at 08:58:37PM +0000, HushBugger wrote:
> Thanks, I don't have a lot of practical C experience.
The reason for the cast is because <ctype.h> is a poorly designed
library where the caller needs to ensure that the arg is representable
as an `unsigned char` (i.e 0 .. UCHAR_MAX) or as `EOF` [0].
for (s = src, i = 0; *s; s++, i++) {
- if (*s == '%' && (sscanf(s + 1, "%2hhx", &n) == 1)) {
+ if (*s == '%' && isxdigit((unsigned char)s[1]) &&
+ isxdigit((unsigned char)s[2])) {
+ sscanf(s + 1, "%2hhx", &n);
dest[i] = n;
s += 2;
At a glance, the `s += 2` looks incorrect to me because it's reading 3
bytes, not 2. But then I saw that the for loop increments `s` as well.
IMO messing around with the loop counter in two places is not a good
idea because it makes the code harder to reason about than it needs to
be. I think the `s++` should be removed from the for loop and `s` should
be incremented as needed inside the loop instead.
- s += 2;
+ s += 3;
} else {
- dest[i] = *s;
+ dest[i] = *s++;
But this is mostly style nit, so feel free to ignore.
[0]: https://port70.net/~nsz/c/c11/n1570.html#7.4
- NRK
