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Re: Consensus: Tuning runtime behaviour with environment variables.
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: Carlos O'Donell <carlos at redhat 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 16:30:35 +0000
- Subject: Re: Consensus: Tuning runtime behaviour with environment variables.
- References: <51A58A92 dot 4050508 at redhat dot com>
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:
* Whether it follows the proposed guidelines.
* 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).
* 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.)
--
Joseph S. Myers
joseph@codesourcery.com