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

[Florian Weimer]

* 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.

Thanks,
Florian