svn commit: r304928 - in head/lib/libc: amd64/sys i386/sys sys

[Andrey Chernov]

On 28.08.2016 3:56, Konstantin Belousov wrote:
> On Sun, Aug 28, 2016 at 03:38:10AM +0300, Andrey Chernov wrote:
>> On 28.08.2016 2:03, Konstantin Belousov wrote:
>>>   Since ptrace(2) syscall can return -1 for non-error situations, libc
>>>   wrappers set errno to 0 before performing the syscall, as the service
>>>   to the caller.
>>
>> Both C99 and POSIX directly prohibits any standard function to set errno
>> to 0. ptrace() should either choose other errno to indicate non-error
>> situation or change return -1 to something else.
>>
> ptrace(2) is not a standard function.
> And, we cannot break ABI for the syscall.
> 

C99 statement sounds stricter:
"The value of errno is zero at program startup, but is never set to zero
by any library function. 176)"
And syscall is not different from library function from C99 point of view.