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

[Andrey Chernov]

On 28.08.2016 3:38, 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.
> 
...and don't touch errno.

POSIX: "No function in this volume of POSIX.1-2008 shall set errno to zero."

> On both i386 and amd64, the errno symbol was directly
> referenced, which only works correctly in single-threaded process.

POSIX: "For each thread of a process, the value of errno shall not be
affected by function calls or assignments to errno by other threads."