Confused by segfault with legitimate call to strerror(3) on amd64 / sysctl (3) setting `odd' errno's

[Garrett Cooper]

On Fri, Jan 16, 2009 at 2:35 AM, Garrett Cooper <yanefbsd at gmail.com> wrote:
> On Fri, Jan 16, 2009 at 2:21 AM, Christoph Mallon
> <christoph.mallon at gmx.de> wrote:
>> Christian Kandeler schrieb:
>>>
>>> On Friday 16 January 2009 09:53, Christoph Mallon wrote:
>>>
>>>>> int
>>>>> main() {
>>>>>
>>>>>        int mib[4];
>>>>>
>>>>>        size_t len;
>>>>>
>>>>>        if (sysctlnametomib("kern.ipc.shmmax", mib, &len) != 0) {
>>>>>                printf("Errno: %d\n", errno);
>>>>>                errx(errno, "Error: %s", strerror(errno));
>>>>
>>>> The use of errno is wrong. printf might change errno.
>>>
>>> I don't think printf() can set errno. And even if it could, it
>>
>> Of course it can. See ISO/IEC 9899:1999 (E) §7.5:3.
>>
>>> wouldn't matter, because C has call-by-value semantics.
>>
>> This has nothing to do with call-by-value. errno is read (even twice!)
>> *after* the call to printf().
>
>    Ok, I just installworld'ed, recompiled the program with the
> following modifications, and I still get segfaults. And the question
> of the night is: why amd64 on a VERY recent CURRENT?
>    I'm going to try the same app on an amd64 freebsd VMware instance
> with RELENG_7.
>    Remember: just because a bunch of other people aren't reporting
> issues with CURRENT/amd64 doesn't mean that it isn't environmental,
> related to my hardware or compile options ;).
> Cheers,
> -Garrett

Ugh... I pasted it twice by accident. Sorry.
-Garrett