From: Bill Gianopoulos <wag@sccux1.msd.ray.com>
Message-Id: <199407192218.SAA29713@sccux1.msd.ray.com>
Subject: Info.Ultrix.VAX
To: <paul@vix.com> (Paul A Vixie)
Date: Tue, 19 Jul 1994 18:18:04 -0400 (EDT)
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This is the stuff I promised you about linking on a ULTRIX VAX platform.

There is a problem in the Ultrix VAX version of the ld command which
causes problems when linking modules using the bind-4.9.3 resolver
library.  The ld command is not working according to the documentation
on its man page which states "If the argument is a library, it is
searched only once at the point it is encountered in the argument list.
Only those routines defining an unresolved external reference are loaded."
In fact, if the library has been processed by ranlib, and a routine
is loaded to resolve an unsatisfied external reference, any other modules
which contain any entry point referenced by that module will be loaded
even if the reference has already been resolved by a previously loaded
module.  This causes duplicate entry points to be loaded and results in
ld errors when you try to link.

The approach I use to get around this problem is to split the standard
Ultrix libc.a into 2 libraries, one called liboldres.a which contains
the resolver routines from the Ultrix release libc.a, and a libc.a which
contains everything except the resolver routines.

It is then possible to link using the released Ultrix resolver by specifying
"-loldres" on the ld (or cc) command, or using the new resolver by specifying
"-lresolv -l44bsd".

the shell script I use to create the 2 libraries follows:

#!/bin/sh
#
# Split the released Ultrix libc.a into 2 libraries.  The resultant
# libc.a will not contain the resolver routines which are present
# in the new libresolv.a which will be built by the bind install.
# The resolver routines from the released Ultrix libc.a will be
# put in a new liboldres.a library.  The original libc.a will be saved
# as libcold.a.
#
if [ -f /usr/lib/libcold.a ]
then
  echo "/usr/lib/libcold.a already exists."
  exit 1
fi
if [ -f /usr/lib/liboldres.a ]
then
  echo "/usr/lib/liboldres.a already exists."
  exit 1
fi
rm -r /tmp/libres$$
mkdir /tmp/libres$$
cd /tmp/libres$$
ar x /usr/lib/libc.a gethostent.o getnetent.o herror.o res_comp.o \
                     res_debug.o res_init.o res_mkquery.o res_query.o \
                     res_send.o
ar r /usr/lib/liboldres.a *.o
ranlib /usr/lib/liboldres.a
cd /tmp
rm -r libres$$
cp /usr/lib/libc.a /usr/lib/libcold.a
ar d /usr/lib/libc.a gethostent.o getnetent.o herror.o res_comp.o \
                     res_debug.o res_init.o res_mkquery.o res_query.o \
                     res_send.o
ranlib /usr/lib/libc.a

-- 
William A. Gianopoulos; Raytheon Missile Systems Division
wag@sccux1.msd.ray.com
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My opinions are my own and do not in any way represent the opinions of my
employer.
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