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Re: Can't build libposix

From: Bruce Korb
Subject: Re: Can't build libposix
Date: Wed, 08 Dec 2010 15:05:36 -0800
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20101026 SUSE/3.0.10 Thunderbird/3.0.10

On 12/08/10 06:11, Gary V. Vaughan wrote:
> If you are on a glibc system, I think the library provides the necessary
> symbol and you should be able to build a working libposix from the topic
> branch after a git pull. Otherwise you'll have to link in the progname
> module, or similar to resolve it... until we come up with a blessed
> method for dealing with it properly.


Scratching my head and fuzzily remembering the problem, the issues are:

1. The error module gets sucked into the POSIX library and it
   will seg fault for you if you have not defined and initialized
   a "char * program_name" global variable.
   This is very bad because it has the unanticipatable consequence
   of requiring the libposix client to know that there are non-posix
   requirements in using this posix library.

2. On some non-ELF systems, if you declare a pointer as in:
     char * program_name;
   that declaration is actually a definition with non-weak linkage.
   i.e. it is not dumped into an "anonymous region(?)".
   This creates a link problem, despite the commonness of using this
   idiom for 40 years.

I think the correct solution is to find a way to have the error
module not seg fault and also to not require non-posix calls be
made in order to use the libposix library.

Possible fixes:

* modify the error module to tolerate a NULL value
  in program_name, defining the variable only where needed
  (using some autoconf wizardry).

* automatically set that value, likewise defining as needed

* figure out how to remove the dependency(ies) that draw it
  into the library.

Just adding the progname module and requiring a non-posix call
is not a good solution (in my completely unhumble opinion).

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