[PATCH v4 2/4] posix: Do not clobber errno by atfork handlers

[Adhemerval Zanella]

On 24/06/2021 08:19, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>> On 24/06/2021 05:19, Florian Weimer wrote:
>>> * Adhemerval Zanella via Libc-alpha:
>>>
>>>> Checked on x86_64-linux-gnu.
>>>> ---
>>>>  posix/fork.c | 5 +++++
>>>>  1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/posix/fork.c b/posix/fork.c
>>>> index 44caf8d166..9340511198 100644
>>>> --- a/posix/fork.c
>>>> +++ b/posix/fork.c
>>>> @@ -103,6 +103,9 @@ __libc_fork (void)
>>>>      }
>>>>    else
>>>>      {
>>>> +      /* If _Fork failed, preserve its errno value.  */
>>>> +      int save_errno = errno;
>>>> +
>>>>        /* Release acquired locks in the multi-threaded case.  */
>>>>        if (multiple_threads)
>>>>  	{
>>>> @@ -115,6 +118,8 @@ __libc_fork (void)
>>>>  
>>>>        /* Run the handlers registered for the parent.  */
>>>>        __run_fork_handlers (atfork_run_parent, multiple_threads);
>>>> +
>>>> +      __set_errno (save_errno);
>>>
>>> I think you should restrict the __set_errno call to pid < 0, so that
>>> errno is not 0 after a different value has been observed by the fork
>>> handlers.
>>
>> OK, I can change it back.  From the previous review iteration I understood
>> you were ok with making it unconditional [1].
>>
>> [1] https://sourceware.org/pipermail/libc-alpha/2021-March/123729.html
> 
> Sorry, I meant making the saving unconditional, not the restoring.

Ok, I will fix it.