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Re: Consensus: Tuning runtime behaviour with environment variables.
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>, Roland McGrath <roland at hack dot frob dot com>, Andreas Jaeger <aj at suse dot com>, "Ryan S. Arnold" <ryan dot arnold at gmail dot com>, Andi Kleen <andi at firstfloor dot org>, David Miller <davem at davemloft dot net>, Siddhesh Poyarekar <siddhesh at redhat dot com>, Andreas Schwab <schwab at suse dot de>
- Date: Fri, 31 May 2013 18:51:14 -0400
- Subject: Re: Consensus: Tuning runtime behaviour with environment variables.
- References: <51A58A92 dot 4050508 at redhat dot com> <Pine dot LNX dot 4 dot 64 dot 1305311622520 dot 9860 at digraph dot polyomino dot org dot uk>
On 05/31/2013 12:30 PM, Joseph S. Myers wrote:
> On Wed, 29 May 2013, Carlos O'Donell wrote:
>
>> We have established prior-art for setting runtime behaviour
>> based on environment variables. It's useful.
>
> I'd like to see a more detailed analysis of the existing prior art. I
> suggest a list of all environment variables used in some way by glibc's
> libraries (as opposed to miscellaneous executables installed by glibc),
> annotated to indicate for each:
I've started the analysis and it will show up here:
http://sourceware.org/glibc/wiki/TuningLibraryRuntimeBehavior#Prior_Art
Just to clarify, when you say "glibc's libraries" I assume you mean all
libraries installed on the users system that they can use including things
like libSegFault and libmemusage? This would also include the set of
loadable NSS modules, and character conversion modules.
> * Whether it follows the proposed guidelines.
OK.
> * Whether it is in UNSECURE_ENVVARS (sysdeps/generic/unsecvars.h) or
> EXTRA_UNSECURE_ENVVARS (sysdeps/unix/sysv/linux/i386/dl-librecon.h) or
> otherwise removed from the environment if __libc_enable_secure
> (MALLOC_CHECK_ unless /etc/suid-debug exists).
OK.
> * Whether it is followed if __libc_enable_secure (which depends e.g. on
> whether __libc_secure_getenv is used). (Together with the previous point,
> you get a tristate, which is probably what should go in the list: removed
> in the secure case; not removed but ignored; not ignored.)
OK.
Cheers,
Carlos.