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From: =?UTF-8?Q?Daniel_Cegie=C5=82ka?= <daniel.cegielka@gmail.com>
Newsgroups: gmane.linux.lib.musl.general
Subject: Re: getrandom syscall
Date: Wed, 28 Jan 2015 13:42:23 +0100
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2015-01-28 13:26 GMT+01:00 Szabolcs Nagy <nsz@port70.net>:
> * Daniel Cegie??ka <daniel.cegielka@gmail.com> [2015-01-28 10:10:53 +0100]:
>> 2015-01-28 10:02 GMT+01:00 Szabolcs Nagy <nsz@port70.net>:
>> >
>> > #ifdef SYS_getrandom
> ...
>> > #endif
>> >
>> > eg sh does not have the syscall (linux is not consistent with
>> > syscalls for whatever reason)
>>
>> SYS_getrandom is defined on musl, so #ifdef SYS_getrandom is not a
>> good solution:
>>
>> http://git.musl-libc.org/cgit/musl/tree/arch/x86_64/bits/syscall.h#n657
>>
>> It's better to return an error.
>
> no
>
> you should return runtime error if the syscall fails
> (eg you are on old kernel that does not support the syscall)
>
> but you cannot use this code if SYS_getrandom is not
> defined (eg. sh arch) because it will be a musl
> compile time failure (sadly linux does not allocate
> syscall numbers on all archs so musl cannot define
> all SYS_ macros consistently on all archs either)

Indeed. I considered the kernel version check, but it is ugly
approach. #ifdef SYS_getrandom we should add also add to the header
file (stdlib.h?). Is this code will be approved for musl?

Daniel