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From: Florian Weimer <fweimer@redhat.com>
To: Peng Yu <pengyu.ut@gmail.com>
Cc: Peng Yu via Libc-help <libc-help@sourceware.org>
Subject: Re: What is the point of IPC_PRIVATE of shmget?
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Date: Mon, 12 Apr 2021 18:14:48 +0200
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 (Peng Yu's message of "Mon, 12 Apr 2021 11:12:50 -0500")
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* Peng Yu:

> On Mon, Apr 12, 2021 at 11:07 AM Florian Weimer <fweimer@redhat.com> wrote:
>>
>> * Peng Yu via Libc-help:
>>
>> > I don't get the point of IPC_PRIVATE of shmget(). Since it is just
>> > used by the current process, why not just use malloc?
>> >
>> > Can anybody give a real example in which IPC_PRIVATE must be used, but
>> >  malloc or other variant of *alloc functions are not appropriate to
>> > use? Thanks.
>>
>> shmget(2) says this:
>>
>> | BUGS
>> |        The name choice IPC_PRIVATE was perhaps unfortunate, IPC_NEW
>> |        would more clearly show its function.
>>
>> Does this answer your question?
>
> No. That is just a naming issue. It is still privately used by the
> current process instead of other processes.

Oh, it can be shared if the process forks.  With malloc, you'd lose the
sharing.

Thanks,
Florian