Should we rename os:: functions that are named like standard C- or Posix-functions?

[Thomas Stüfe]

On Thu, Jun 30, 2022 at 7:21 AM David Holmes <david.holmes at oracle.com>
wrote:

> Hi Thomas,
>
> On 30/06/2022 2:57 pm, Thomas Stüfe wrote:
> > Hi,
> >
> > several functions in the os:: name scope are deliberately named like the
> > official counterparts they replace:
> >
> > os::malloc, os::free, os::strdup, os::realloc, os::recv, os::send,
> > os::connect, os::signal...
> >
> > There may be more. Some of them argument-match their counterparts (e.g.
> > os::free), while others don't.
> >
> > Since the os:: variants can be called inside the os:: namespace with
> > omitting the leading os::, name confusions are possible. "free(p)" means
> > something different in global scope or inside an os:: function.
> >
> > This can lead to problems that are difficult to find, e.g., mismatched
> > (os::)malloc->(os::)free with the potential to corrupt the C-heap:
> >
> > https://bugs.openjdk.org/browse/JDK-8289477
> > <https://bugs.openjdk.org/browse/JDK-8289477>
> >
> > And I remember having similar problems in the past. They don't happen
> > often, but if they do, they take some investigation time since they are
> > rarely obvious.
> >
> > I discussed the above problem with the muslc devs
> > https://www.openwall.com/lists/musl/2022/06/29/3
> > <https://www.openwall.com/lists/musl/2022/06/29/3>, and their position
> > is understandable that we should not use names of standard functions.
> >
> > So I wonder if we should do that. Rename os::<function> to something
> > like os::<prefix><function>. And what the prefix or suffix would be.
>
> It annoys me that we have to do such things. It would have made more
> sense for the standard C library routines to have a prefix that marked
> them as reserved identifiers rather than polluting the global namespace
> the way they did. But no one thinks of these things initially and by the
> time it is standardised it is too late to make such changes. :(
>
>
I am not sure that would have helped. The original VM authors seemed to
deliberately duplicate the official names. Had the inventors of the
C-standard used a common prefix, we may have copied that too. But that's
ancient history, I don't know who introduced os:: and what their thoughts
were.


> I'm not sure this is a problem we have to address, but if we choose to
> then I think we should try to make a general improvement to the way os
> is used.
>
> Maybe, as I think has been suggested before, we can move these out of
> the os class as they are not really about the os but the C library, and
> then any renaming that includes a prefix may not look so bad?
>
> Maybe lib::C_free(), lib::C_malloc() etc?
>
>
I'd be fine with that. Other possibilities for such a namespace could be
"system" or permutations thereof, e.g. "sys::c_free()" etc. Avoids
discussions about what is a C-standard function, what is a Posix function,
etc.

Cheers, Thomas

Cheers,
> David
> -----
>
> > Thanks, Thomas
> >
>
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