[vlc-devel] [PATCH 1/2] compat: Workaround sendmsg bug on some ArmV8 Android devices

[Rémi Denis-Courmont]

I can only think of three ways to solve this:
1) Custom headers pretending that return type is int (will potentially break non-buggy devices tough).
2) Interposed wrappers for all affected calls.
3) Replacement (asm) implementation for all affected calls.

It can't be done in VLC build system as the problem affects contribs too.

Le 4 avril 2019 14:45:53 GMT+03:00, "Hugo Beauzée-Luyssen" <hugo at beauzee.fr> a écrit :
>On Thu, Apr 4, 2019, at 1:42 PM, Rémi Denis-Courmont wrote:
>> Hi all,
>> 
>> 5 minutes git archeology through bionic repo leads to this:
>>
>https://android.googlesource.com/platform/bionic.git/+/3d19a8319b9c27af8aa5cfbf495da0fe7fa62d3e
>> 
>> The bug affect basically all system call wrappers with a signed
>64-bits 
>> return value type (including ssize_t).
>> 
>> Clearly this patch ain't going to work.
>> 
>> Le 4 avril 2019 10:54:44 GMT+03:00, "Hugo Beauzée-Luyssen" 
>> <hugo at beauzee.fr> a écrit : On Wed, Apr 3, 2019, at 9:24 PM, Rémi 
>> Denis-Courmont wrote:
>> >> I don't know what you did or did not imply. When somebody states
>that a patch 
>> >> is ugly, I tend to assume that they dislike the form rather than
>the essence.
>> >> 
>> >> My chief concerns are that, on the one hand, other system calls
>may also 
>> >> exhibit the bug, and on the other hand, contribs may be affected
>as well. In 
>> >> other words, I am concerned not that the patch is ugly, but that
>does not 
>> >> solve the problem(s).
>> > 
>> > It solves the observed problem, but it doesn't solve problems I
>don't know about indeed.
>> 
>
>Hi,
>
>Let aside the passive aggressiveness of the reply, this is exactly what
>I was hoping for by submitting the patch, that someone who knows
>libc/kernel more than I do figures out what the problem is.
>I looked at the syscall wrapper but did not check the __set_errno it
>called, that's my bad.
>
>Thanks for finding the actual error.
>
>-- 
>  Hugo Beauzée-Luyssen
>  hugo at beauzee.fr
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