* Libtool

reminder about shlibs' usefulness
problems:
- why need PIC
- tools used to build shlibs vs. static libs
- gcc can use gld or native ld, ditto for g/as
- shlibs points to anywhere on system, what if previous vers. installed
  => need to dyn. link against correct shlib
     but that's different than what's actually installed

** ldd: finding what shlibs a binary is linked with?

$ ldd /bin/ls
        libtermcap.so.2 => /lib/libtermcap.so.2 (0x4002c000)
        libc.so.6 => /lib/libc.so.6 (0x40030000)
        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

AIX ) alias ldd="dump -H" ;;
IRIX* ) alias ldd="elfdump -L" ;;
HP* ) alias ldd="chatr" ;;
OSF1 ) alias ldd="odump -D" ;; # odump -Dl gives brief info

libtool to the rescue!

** SRCDIR/configure.in

add AC_PROG_LIBTOOL after AC_PROG_CC
comment out AC_CANONICAL_HOST (dup use)

(See section 4.8 of Autoconf manual)
add        
  AC_CONFIG_COMMANDS_PRE(
  [LTLIBOBJS=`echo $LIBOBJS | sed 's/\.o/\.lo/g'`
  AC_SUBST(LTLIBOBJS)])
will be run right before AC_OUTPUT is run

why? b/c autoconf builds $LIBOBJS while it runs, listing .o files that it
needs to build, but libtool wants this list of .o files to be in LTLIBOBJS,
and it wants them to have a different extension: .lo, so it can distinguish
b/t static and dynamic object files.

** in all Makefile.am's

libskey.a -> libskey.la
libskey_a -> libskey_la
LIBRARIES -> LTLIBRARIES

** SRCDIR/lib/Makefile.am

lib_LTLIBRARIES = libskey.la
libskey_la_SOURCES = skeylogin.c skeysubr.c md4.c put.c

** SRCDIR/tools/Makefile.am

LDADD = ../lib/libskey.la

** next, bootstrapping

- rerun bootstrap
- automake will copy ltmain.sh script
  => main driver script for libtool,  no need to touch, edit, etc.
	script gets distributed automatically for you
	4984 lines long!

** configure

./configure --{enable,disable}-{static,shared}
	both enabled
so, to build only shared
./configure --disable-static

** running make in BUILDDIR/lib

instead of: gcc -c foo.c
/bin/sh ../libtool --mode=compile gcc -c foo.c
	=> gcc -c foo.c -fPIC -DPIC -o foo.lo
builds libskey.la: wrapper around real shlib
	.libs/libskey.so

** make in BUILDDIR/tools

also uses libtool driver script to dynamically link

builds tools/skey as a special wrapper shell script
tools/.lib/skey is binary ready to be installed
	points to shlib that's NOT yet installed
	won't run directly out of BUILDDIR/tools/.lib

- if run "make install", will install shlib + real skey binary, so it'll
  point to where the shlib is now installed

- if run BUILDDIR/tools/skey wrapper script, will execute specially built
  skey binary in BUILDDIR/tools/.libs/skey, which'll use the shlib just
  built in SRCDIR/lib/.libs/; will relink a new binary called
  BUILDDIR/tools/.libs/lt-skey which is shlib-linked to point not to final
  target of shlib ($INSTALLDIR/lib) but BUILDDIR/lib/.libs.

summary: configure, make, and make install "just work magically"


* Testing and regression suites

Section 16.1 in online Automake manual

*  SRCDIR/tools/Makefile.am

TESTS = test1.sh
EXTRA_DIST = $(TESTS)

XFAIL_TESTS = test2.sh ...

exit 0 to indicate success
exit 1 to indicate failure
exit 77 to indicate test is not applicable on this system


* SRCDIR/tools/test1.sh
$ chmod a+rx test1.sh
$ cat test1.sh

#!/bin/sh
# run s/key with sequence 88, key ka9q2, and passphrase "foobar"

msg=`echo foobar | ./skey 88 ka9q2 | tail -1`

if test "$msg" != "WORN MUD CORK DARK MONT HAP"
then
    exit 1
else
    exit 0
fi

* running test

$ make check
> PASS: test1.sh
> ==================
> All 1 tests passed
> ==================

- runs all tests
- reports no. of tests that succeeded, failed, or ignore


* misc

posted grading criteria for project
	last one is version 6 (minor changes and clarifications)
handout #10: sample final exam
course/TA eval forms
will be around until midnight, then post list of submissions.
register for demo w/ TA
	demo in which room?
	grades within 48 hours
	48 more hours for any questions/disputes
final exam Thu 12/20, 5-7:30pm, ESS-001


* new macro: checking for externals

AC_DEFUN(AC_CHECK_EXTERN,
[
# store variable name for external definition
exname=`echo $1 | tr 'a-z 'A-Z`
tmp=HAVE_EXTERN_$exname
# this pattern assumes that the complete external definition is on one line
pattern="(extern)?.*[[^a-zA-Z0-9_]]$1[[^a-zA-Z0-9_]]?.*\(.*\).*;"

AC_EGREP_CPP(${pattern},
[
# include <sys/types.h>
# include <stdio.h>
], AC_DEFINE_UNQUOTED($tmp))

])


* writing new macros

- add to acinclude.m4
- rerun aclocal

* reaching the limits of capability, limited by C

detect the type of an argument:

	foo(int arg)
	foo(unsigned int arg)
	foo(long arg)

can detect such things w/ gcc -Wall -Werror, but only works for gcc
can do fancy parsing of headers, but need full C parser for this

ugly, but works:

case $host_os in
	linux )
		AC_DEFINE_UNQUOTED(FOO_FXN_TYPE, "int")
	;;
	* )	# all others
		AC_DEFINE_UNQUOTED(FOO_FXN_TYPE, "long")
	;;
esac