musl - Re: [feature request] add mallinfo support

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Message-ID: <CAPMgRLSib8gV=5rnjEomY-XfTYZitZ-gHv+7j2Gw7k79Hqpv2g@mail.gmail.com>
Date: Thu, 18 Jan 2018 10:28:35 +0100
From: Gonzalo Brito Gadeschi <gonzalo.gadeschi@...h-aachen.de>
To: Rich Felker <dalias@...c.org>
CC: <musl@...ts.openwall.com>
Subject: Re: [feature request] add mallinfo support

Thanks for the quick reply.

> Omission of mallinfo is largely intentional.

Makes sense, it would have saved me some time if this
information would be added to the FAQ. I tried to search
the mailing list (or musl website for a bug tracker) without
any luck.

> The API is fundamentally
broken (using type int which cannot represent sizes) and tracking the
information it provides imposes nontrivial costs on the malloc
implementation.

I agree.

> http://www.openwall.com/lists/musl/2013/11/09/2
I went through the thread and could not find the piece of information
that lead to that opinion (maybe I am just generally bad at mailing lists).

Rich Felker (you :D) argued:

> The main reason I'd want to provide a dummy is if
> there are glibc binaries using it. The range of the counters
> is fairly irrelevant; keeping track of the information is prohibitively
> slow anyway since it would have to be synchronized between
> threads on each call to malloc/free. (glibc does some poor
> hack keeping this info per-arena and summarizing it when
mallinfo is called, I think...)

And Szabolcs Nagy just answered:

> i see

That's all I found there.

FWIW I wouldn't mind if mallinfo on musl
would just return a zeroed mallinfo struct,
because I don't even know if the function is
called at all: I just know that the code won't
compile without those symbols.

Arguably, I can do that workaround myself,
so I'll just do that for now.

Thanks again for the quick reply!
Gonzalo

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