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From: Quentin Rameau <quinq@fifth.space>
To: musl@lists.openwall.com
Subject: Re: [musl] Bug in atoll strtoll, the output of then differ
Date: Sun, 18 Dec 2022 11:06:14 +0100	[thread overview]
Message-ID: <20221218110320.5e3979a4.quinq@fifth.space> (raw)
In-Reply-To: <f1c6f16a-a6fd-8447-5f9b-d3d25a044af4@gmail.com>

> Hello !

Hi,

> 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;
> }

This is not a bug in musl, but a bug in the code,
9223372036854775808 is outside the range of long long,
so the behavior is undefined.

As recommended by the standard, ato* should only be used if the input
is known to always be in the target range,
otherwise use the strto* functins and do proper error handling.

  parent reply	other threads:[~2022-12-18 10:06 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-18  9:32 Domingo Alvarez Duarte
2022-12-18  9:58 ` Markus Wichmann
2022-12-18 10:22   ` Domingo Alvarez Duarte
2022-12-18 11:10     ` Markus Wichmann
2022-12-18 10:06 ` Quentin Rameau [this message]
2022-12-18 12:23 ` Szabolcs Nagy
2022-12-18 15:25 ` Rich Felker

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