Re: For review: pidfd_open(2) manual page

From: Florian Weimer
Date: Mon Sep 23 2019 - 16:41:30 EST


* Michael Kerrisk:

>>> static
>>> int pidfd_open(pid_t pid, unsigned int flags)
>>> {
>>> return syscall(__NR_pidfd_open, pid, flags);
>>> }
>>
>> Please call this function something else (not pidfd_open), so that the
>> example continues to work if glibc provides the system call wrapper.
>
> I figured that if the syscall does get added to glibc, then I would
> modify the example. In the meantime, this does seem the most natural
> way of doing things, since the example then uses the real syscall
> name as it would be used if there were a wrapper function.

The problem is that programs do this as well, so they fail to build
once they are built on a newer glibc version.

> But, this leads to the question: what do you think the likelihood
> is that this system call will land in glibc?

Quite likely. It's easy enough to document, there are no P&C issues,
and it doesn't need any new types.

pidfd_send_signal is slightly more difficult because we probably need
to add rt_sigqueueinfo first, for consistency.