Re: unsafe C

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From	Meredith Montgomery <mmontgomery@levado.to>
Newsgroups	comp.lang.c
Subject	Re: unsafe C
Date	Sat, 25 Dec 2021 21:42:00 -0300
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Meredith Montgomery <mmontgomery@levado.to> writes:

> ram@zedat.fu-berlin.de (Stefan Ram) writes:
>
>> Meredith Montgomery <mmontgomery@levado.to> writes:
>>>> it is funny that this is a  warning and not an error.
>>
>>>int scan_ulong(register char *s, register unsigned long *u) 
>>>{
>>>  register unsigned int pos;
>> ...
>>>  return pos;
>>>}
>>
>>   It returns the /unsigned/ int "pos", but its return type is
>>   declared /signed/ int?
>>
>>   /u/ is accessed at most once in the function, but declared
>>   "register"?
>
> Let's see.  I don't think I would've changed that much, but I might.
> Lol.  I did.  I can't even copy properly!  Thanks for spotting that.
>
> Hm, wait!  The check for overflow is not his.  It's mine.  Alas, memory
> failing me.  Daniel J. Bernstein, sorry about that.
>
> /* Public domain. */
>
> #include "scan.h"
>
> unsigned int scan_ulong(register const char *s,register unsigned long *u)
> {
>   register unsigned int pos = 0;
>   register unsigned long result = 0;
>   register unsigned long c;
>   while ((c = (unsigned long) (unsigned char) (s[pos] - '0')) < 10) {
>     result = result * 10 + c;
>     ++pos;
>   }
>   *u = result;
>   return pos;
> }
>
> But, yes, he did qualify u with ``register''.

By the way, that's src/scan_ulong.c in daemontools 0.76.

Thread

unsafe C Thiago Adams <thiago.adams@gmail.com> - 2021-12-17 12:13 -0800
  Re: unsafe C Thiago Adams <thiago.adams@gmail.com> - 2021-12-17 12:16 -0800
    Re: unsafe C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-17 12:25 -0800
    Re: unsafe C Meredith Montgomery <mmontgomery@levado.to> - 2021-12-18 12:40 -0300
      Re: unsafe C Meredith Montgomery <mmontgomery@levado.to> - 2021-12-25 21:41 -0300
        Re: unsafe C Meredith Montgomery <mmontgomery@levado.to> - 2021-12-25 21:42 -0300
    Re: unsafe C Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-18 12:29 -0800
  Re: unsafe C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-17 12:20 -0800
    Re: unsafe C Thiago Adams <thiago.adams@gmail.com> - 2021-12-17 12:29 -0800
    Re: unsafe C Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2021-12-19 17:16 +1100
      Re: unsafe C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-19 13:32 -0800
  Re: unsafe C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-17 20:30 +0000
    Re: unsafe C Thiago Adams <thiago.adams@gmail.com> - 2021-12-17 12:35 -0800

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