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Message-ID: <1499b0ba-f828-6922-a620-24971fb64c8b@gmail.com>
Date: Sun, 18 Dec 2022 11:22:59 +0100
From: Domingo Alvarez Duarte <mingodad@...il.com>
To: musl@...ts.openwall.com
Subject: Re: Bug in atoll strtoll, the output of then differ
Here is the "glibc" implementation of "atoll":
=====
/* Convert a string to a long long int. */
long long int
atoll (const char *nptr)
{
return strtoll (nptr, (char **) NULL, 10);
}
=====
With that there is no way for get different results from "atolll" and
"strtoll".
Cheers !
On 18/12/22 10:58, Markus Wichmann wrote:
> On Sun, Dec 18, 2022 at 10:32:10AM +0100, Domingo Alvarez Duarte wrote:
>> Hello !
>>
>> Doing some work with emscripten with this project
>> https://github.com/mingodad/CG-SQL-Lua-playground I was getting some errors
>> with the usage of "atoll" and with this small program to compare the output
>> of "musl" and "glibc" I found what seems to be a bug in "atoll" because with
>> "musl" it gives a different output than "strtoll".
>>
>> =====
>>
>> #include <stdio.h>
>> #include <stdlib.h>
>>
>> int main(int argc, char *argv[])
>> {
>> const char *s = "9223372036854775808";
>> long long ll = atoll(s);
>> long long ll2 = strtoll (s, (char **) NULL, 10);
>> int imax = 0x7fffffff;
>> printf("%s : %lld : %lld : %d : %d\n", s, ll, ll2, imax, ll <= imax);
>> return 0;
>> }
>>
>> =====
>>
>> Output from "glibc":
>>
>> =====
>>
>> 9223372036854775808 : 9223372036854775807 : 9223372036854775807 : 2147483647
>> : 0
>>
>> =====
>>
>> Output from "musl":
>>
>> =====
>>
>> 9223372036854775808 : -9223372036854775808 : 9223372036854775807 :
>> 2147483647 : 1
>>
>> =====
>>
>> Cheers !
>>
> Well, your problem here is that ato* behavior on error is not defined.
> The C standard explicitly excepts behavior on error from the requirement
> that these functions return the same thing as their strto* counterparts,
> and §7.24.1 (of C23) explicitly states that behavior in that case is
> undefined.
>
> This means that a test case is wrong; no result is defined. Actually, a
> crash would be acceptable behavior. This also means that when I return
> to work next year, I should really go through my code base and replace
> all ato* calls with their strto* counterparts for that reason alone.
>
> Ciao,
> Markus
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