Re: ltdl and C++

[Alessandro Candini]

On 21/09/11 10:14, Alessandro Candini wrote:
> On 20/09/11 17:04, Nick Bowler wrote:
> > On 2011-09-19 15:34 +0200, Alessandro Candini wrote:
> > > Configure and make works but I do not produce a dynamic linked
> > > executable, unlike the original John's example:
> > > ../src $ ldd hello
> > >       not a dynamic executable
> > This is normal.  When libtool creates an executable that links against
> > other libtool libraries in your source tree, it creates a shell script
> > to run the program in-place so that you don't need to install it.  You
> > haven't shown us your Makefile.am, but I assume it contains something
> > like hello_LDFLAGS = -dlopen plugin.la.
> >
> > You appear to be running ldd on that shell script, so of course it's
> > "not a dynamic executable".  The actual binary that gets installed is
> > located in .libs/.
> >
> > If you want to run ldd on an uninstalled executable, do it through
> > libtool:
> >
> >    libtool --mode=execute ldd hello
> >
> > Hope that helps,
> Thank you Nick, I didn't get that those file were not binary 
> executable files, but shell scripts:
>
> Working example:
> $ book/jupiter-libtool-ch7/src $ file jupiter
> jupiter: Bourne-Again shell script text executable
>
> My not working example:
> $ hello_chap7/src $ file hello
> hello: Bourne-Again shell script text executable
>
> But the problem remains: the original one can load and use the dynamic 
> library but my example doesn't.
> And if I look at the make output, the only difference I can notice is 
> the presence in my example of the -fPIC -DPIC flags.
>
> Build on working example:
> make  all-recursive
> make[1]: Entering directory `jupiter-libtool-ch7'
> Making all in common
> make[2]: Entering directory `jupiter-libtool-ch7/common'
> /bin/bash ../libtool --tag=CC   --mode=compile gcc -DHAVE_CONFIG_H -I. 
> -I..     -g -O2 -MT print.lo -MD -MP -MF .deps/print.Tpo -c -o 
> print.lo print.c
> libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -g -O2 -MT print.lo 
> -MD -MP -MF .deps/print.Tpo -c print.c  -fPIC -DPIC -o .libs/print.o
> libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -g -O2 -MT print.lo 
> -MD -MP -MF .deps/print.Tpo -c print.c -o print.o >/dev/null 2>&1
> mv -f .deps/print.Tpo .deps/print.Plo
> /bin/bash ../libtool --tag=CC   --mode=link gcc  -g -O2   -o 
> libjupcommon.la  print.lo  -lltdl -lpthread
> libtool: link: ar cru .libs/libjupcommon.a .libs/print.o
> libtool: link: ranlib .libs/libjupcommon.a
> libtool: link: ( cd ".libs" && rm -f "libjupcommon.la" && ln -s 
> "../libjupcommon.la" "libjupcommon.la" )
> make[2]: Leaving directory `jupiter-libtool-ch7/common'
> Making all in include
> make[2]: Entering directory `jupiter-libtool-ch7/include'
> make[2]: Nothing to be done for `all'.
> make[2]: Leaving directory `jupiter-libtool-ch7/include'
> Making all in libjup
> make[2]: Entering directory `jupiter-libtool-ch7/libjup'
> /bin/bash ../libtool  --tag=CC   --mode=compile gcc -DHAVE_CONFIG_H 
> -I. -I..  -I../include -I../common   -g -O2 -MT 
> libjupiter_la-jup_print.lo -MD -MP -MF 
> .deps/libjupiter_la-jup_print.Tpo -c -o libjupiter_la-jup_print.lo 
> `test -f 'jup_print.c' || echo './'`jup_print.c
> libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -I../include 
> -I../common -g -O2 -MT libjupiter_la-jup_print.lo -MD -MP -MF 
> .deps/libjupiter_la-jup_print.Tpo -c jup_print.c  -fPIC -DPIC -o 
> .libs/libjupiter_la-jup_print.o
> libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -I../include 
> -I../common -g -O2 -MT libjupiter_la-jup_print.lo -MD -MP -MF 
> .deps/libjupiter_la-jup_print.Tpo -c jup_print.c -o 
> libjupiter_la-jup_print.o >/dev/null 2>&1
> mv -f .deps/libjupiter_la-jup_print.Tpo .deps/libjupiter_la-jup_print.Plo
> /bin/bash ../libtool --tag=CC   --mode=link gcc  -g -O2   -o 
> libjupiter.la -rpath /usr/local/lib libjupiter_la-jup_print.lo 
> ../common/libjupcommon.la -lltdl -lpthread
> libtool: link: gcc -shared  .libs/libjupiter_la-jup_print.o  
> -Wl,--whole-archive ../common/.libs/libjupcommon.a 
> -Wl,--no-whole-archive  -ldl /usr/lib/libltdl.so -lpthread    
> -Wl,-soname -Wl,libjupiter.so.0 -o .libs/libjupiter.so.0.0.0
> libtool: link: (cd ".libs" && rm -f "libjupiter.so.0" && ln -s 
> "libjupiter.so.0.0.0" "libjupiter.so.0")
> libtool: link: (cd ".libs" && rm -f "libjupiter.so" && ln -s 
> "libjupiter.so.0.0.0" "libjupiter.so")
> libtool: link: (cd .libs/libjupiter.lax/libjupcommon.a && ar x 
> "jupiter-libtool-ch7/libjup/../common/.libs/libjupcommon.a")
> libtool: link: ar cru .libs/libjupiter.a  libjupiter_la-jup_print.o  
> .libs/libjupiter.lax/libjupcommon.a/print.o
> libtool: link: ranlib .libs/libjupiter.a
> libtool: link: rm -fr .libs/libjupiter.lax
> libtool: link: ( cd ".libs" && rm -f "libjupiter.la" && ln -s 
> "../libjupiter.la" "libjupiter.la" )
> make[2]: Leaving directory `jupiter-libtool-ch7/libjup'
> Making all in src
> make[2]: Entering directory `jupiter-libtool-ch7/src'
> Making all in modules/hithere
> make[3]: Entering directory `jupiter-libtool-ch7/src/modules/hithere'
> /bin/bash ../../../libtool --tag=CC   --mode=compile gcc 
> -DHAVE_CONFIG_H -I. -I../../..     -g -O2 -MT hithere.lo -MD -MP -MF 
> .deps/hithere.Tpo -c -o hithere.lo hithere.c
> libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I../../.. -g -O2 -MT 
> hithere.lo -MD -MP -MF .deps/hithere.Tpo -c hithere.c  -fPIC -DPIC -o 
> .libs/hithere.o
> libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I../../.. -g -O2 -MT 
> hithere.lo -MD -MP -MF .deps/hithere.Tpo -c hithere.c -o hithere.o 
> >/dev/null 2>&1
> mv -f .deps/hithere.Tpo .deps/hithere.Plo
> /bin/bash ../../../libtool --tag=CC   --mode=link gcc  -g -O2 -module 
> -avoid-version  -o hithere.la -rpath /usr/local/lib/jupiter 
> hithere.lo  -lltdl -lpthread
> libtool: link: gcc -shared  .libs/hithere.o   /usr/lib/libltdl.so 
> -lpthread    -Wl,-soname -Wl,hithere.so -o .libs/hithere.so
> libtool: link: ar cru .libs/hithere.a  hithere.o
> libtool: link: ranlib .libs/hithere.a
> libtool: link: ( cd ".libs" && rm -f "hithere.la" && ln -s 
> "../hithere.la" "hithere.la" )
> make[3]: Leaving directory `jupiter-libtool-ch7/src/modules/hithere'
> make[3]: Entering directory `jupiter-libtool-ch7/src'
> gcc -DHAVE_CONFIG_H -I. -I..  -I../include   -g -O2 -MT jupiter-main.o 
> -MD -MP -MF .deps/jupiter-main.Tpo -c -o jupiter-main.o `test -f 
> 'main.c' || echo './'`main.c
> mv -f .deps/jupiter-main.Tpo .deps/jupiter-main.Po
> /bin/bash ../libtool --tag=CC   --mode=link gcc  -g -O2   -o jupiter 
> jupiter-main.o ../libjup/libjupiter.la -dlopen 
> modules/hithere/hithere.la -lltdl -lpthread
> libtool: link: rm -f .libs/jupiter.nm .libs/jupiter.nmS .libs/jupiter.nmT
> libtool: link: (cd .libs && gcc -g -O2 -c -fno-builtin "jupiterS.c")
> libtool: link: rm -f ".libs/jupiterS.c" ".libs/jupiter.nm" 
> ".libs/jupiter.nmS" ".libs/jupiter.nmT"
> libtool: link: gcc -g -O2 -o .libs/jupiter jupiter-main.o 
> .libs/jupiterS.o  ../libjup/.libs/libjupiter.so /usr/lib/libltdl.so 
> -lpthread
> make[3]: Leaving directory `jupiter-libtool-ch7/src'
> make[2]: Leaving directory `jupiter-libtool-ch7/src'
> make[2]: Entering directory `jupiter-libtool-ch7'
> make[2]: Leaving directory `jupiter-libtool-ch7'
> make[1]: Leaving directory `jupiter-libtool-ch7'
>
> Build on my not working example:
> make  all-recursive
> make[1]: Entering directory `hello_chap7'
> Making all in common
> make[2]: Entering directory `hello_chap7/common'
> /bin/bash ../libtool --tag=CXX   --mode=compile g++ -DHAVE_CONFIG_H 
> -I. -I..     -Wall -g -O2 -MT print.lo -MD -MP -MF .deps/print.Tpo -c 
> -o print.lo print.cpp
> libtool: compile:  g++ -DHAVE_CONFIG_H -I. -I.. -Wall -g -O2 -MT 
> print.lo -MD -MP -MF .deps/print.Tpo -c print.cpp  -fPIC -DPIC -o 
> .libs/print.o
> libtool: compile:  g++ -DHAVE_CONFIG_H -I. -I.. -Wall -g -O2 -MT 
> print.lo -MD -MP -MF .deps/print.Tpo -c print.cpp -o print.o 
> >/dev/null 2>&1
> mv -f .deps/print.Tpo .deps/print.Plo
> /bin/bash ../libtool --tag=CXX   --mode=link g++  -Wall -g -O2   -o 
> libhellocommon.la  print.lo  -lltdl -lpthread
> libtool: link: ar cru .libs/libhellocommon.a .libs/print.o
> libtool: link: ranlib .libs/libhellocommon.a
> libtool: link: ( cd ".libs" && rm -f "libhellocommon.la" && ln -s 
> "../libhellocommon.la" "libhellocommon.la" )
> make[2]: Leaving directory `hello_chap7/common'
> Making all in include
> make[2]: Entering directory `hello_chap7/include'
> make[2]: Nothing to be done for `all'.
> make[2]: Leaving directory `hello_chap7/include'
> Making all in libhello
> make[2]: Entering directory `hello_chap7/libhello'
> /bin/bash ../libtool  --tag=CXX   --mode=compile g++ -DHAVE_CONFIG_H 
> -I. -I..  -I../include -I../common   -Wall -g -O2 -MT 
> libhello_la-hello_print.lo -MD -MP -MF 
> .deps/libhello_la-hello_print.Tpo -c -o libhello_la-hello_print.lo 
> `test -f 'hello_print.cpp' || echo './'`hello_print.cpp
> libtool: compile:  g++ -DHAVE_CONFIG_H -I. -I.. -I../include 
> -I../common -Wall -g -O2 -MT libhello_la-hello_print.lo -MD -MP -MF 
> .deps/libhello_la-hello_print.Tpo -c hello_print.cpp  -fPIC -DPIC -o 
> .libs/libhello_la-hello_print.o
> libtool: compile:  g++ -DHAVE_CONFIG_H -I. -I.. -I../include 
> -I../common -Wall -g -O2 -MT libhello_la-hello_print.lo -MD -MP -MF 
> .deps/libhello_la-hello_print.Tpo -c hello_print.cpp -o 
> libhello_la-hello_print.o >/dev/null 2>&1
> mv -f .deps/libhello_la-hello_print.Tpo .deps/libhello_la-hello_print.Plo
> /bin/bash ../libtool --tag=CXX   --mode=link g++  -Wall -g -O2   -o 
> libhello.la -rpath /usr/local/lib libhello_la-hello_print.lo 
> ../common/libhellocommon.la -lltdl -lpthread
> libtool: link: g++ -shared -nostdlib 
> /usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/../../../crti.o 
> /usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/crtbeginS.o  
> .libs/libhello_la-hello_print.o  -Wl,--whole-archive 
> ../common/.libs/libhellocommon.a -Wl,--no-whole-archive  -ldl 
> /usr/lib/libltdl.so -lpthread 
> -L/usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2 
> -L/usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/../../.. 
> -L/usr/lib/x86_64-linux-gnu -lstdc++ -lm -lc -lgcc_s 
> /usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/crtendS.o 
> /usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/../../../crtn.o    -Wl,-soname 
> -Wl,libhello.so.0 -o .libs/libhello.so.0.0.0
> libtool: link: (cd ".libs" && rm -f "libhello.so.0" && ln -s 
> "libhello.so.0.0.0" "libhello.so.0")
> libtool: link: (cd ".libs" && rm -f "libhello.so" && ln -s 
> "libhello.so.0.0.0" "libhello.so")
> libtool: link: (cd .libs/libhello.lax/libhellocommon.a && ar x 
> "hello_chap7/libhello/../common/.libs/libhellocommon.a")
> libtool: link: ar cru .libs/libhello.a  libhello_la-hello_print.o  
> .libs/libhello.lax/libhellocommon.a/print.o
> libtool: link: ranlib .libs/libhello.a
> libtool: link: rm -fr .libs/libhello.lax
> libtool: link: ( cd ".libs" && rm -f "libhello.la" && ln -s 
> "../libhello.la" "libhello.la" )
> make[2]: Leaving directory `hello_chap7/libhello'
> Making all in src
> make[2]: Entering directory `hello_chap7/src'
> Making all in modules/hithere
> make[3]: Entering directory `hello_chap7/src/modules/hithere'
> /bin/bash ../../../libtool --tag=CXX   --mode=compile g++ 
> -DHAVE_CONFIG_H -I. -I../../..     -Wall -g -O2 -MT hithere.lo -MD -MP 
> -MF .deps/hithere.Tpo -c -o hithere.lo hithere.cpp
> libtool: compile:  g++ -DHAVE_CONFIG_H -I. -I../../.. -Wall -g -O2 -MT 
> hithere.lo -MD -MP -MF .deps/hithere.Tpo -c hithere.cpp  -fPIC -DPIC 
> -o .libs/hithere.o
> libtool: compile:  g++ -DHAVE_CONFIG_H -I. -I../../.. -Wall -g -O2 -MT 
> hithere.lo -MD -MP -MF .deps/hithere.Tpo -c hithere.cpp -o hithere.o 
> >/dev/null 2>&1
> mv -f .deps/hithere.Tpo .deps/hithere.Plo
> /bin/bash ../../../libtool --tag=CXX   --mode=link g++  -Wall -g -O2 
> -module -avoid-version  -o hithere.la -rpath /usr/local/lib/hello 
> hithere.lo  -lltdl -lpthread
> libtool: link: g++ -shared -nostdlib 
> /usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/../../../crti.o 
> /usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/crtbeginS.o  
> .libs/hithere.o   /usr/lib/libltdl.so -lpthread 
> -L/usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2 
> -L/usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/../../.. 
> -L/usr/lib/x86_64-linux-gnu -lstdc++ -lm -lc -lgcc_s 
> /usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/crtendS.o 
> /usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.5.2/../../../crtn.o    -Wl,-soname 
> -Wl,hithere.so -o .libs/hithere.so
> libtool: link: ar cru .libs/hithere.a  hithere.o
> libtool: link: ranlib .libs/hithere.a
> libtool: link: ( cd ".libs" && rm -f "hithere.la" && ln -s 
> "../hithere.la" "hithere.la" )
> make[3]: Leaving directory `hello_chap7/src/modules/hithere'
> make[3]: Entering directory `hello_chap7/src'
> g++ -DHAVE_CONFIG_H -I. -I..  -I../include   -Wall -g -O2 -MT 
> hello-hello.o -MD -MP -MF .deps/hello-hello.Tpo -c -o hello-hello.o 
> `test -f 'hello.cpp' || echo './'`hello.cpp
> mv -f .deps/hello-hello.Tpo .deps/hello-hello.Po
> /bin/bash ../libtool --tag=CXX   --mode=link g++  -Wall -g -O2   -o 
> hello hello-hello.o ../libhello/libhello.la -dlopen 
> modules/hithere/hithere.la -lltdl -lpthread
> libtool: link: rm -f .libs/hello.nm .libs/hello.nmS .libs/hello.nmT
> libtool: link: (cd .libs && gcc -g -O2 -c -fno-builtin "helloS.c")
> libtool: link: rm -f ".libs/helloS.c" ".libs/hello.nm" 
> ".libs/hello.nmS" ".libs/hello.nmT"
> libtool: link: g++ -Wall -g -O2 -o .libs/hello hello-hello.o 
> .libs/helloS.o  ../libhello/.libs/libhello.so /usr/lib/libltdl.so 
> -lpthread
> make[3]: Leaving directory `hello_chap7/src'
> make[2]: Leaving directory `hello_chap7/src'
> make[2]: Entering directory `hello_chap7'
> make[2]: Leaving directory `hello_chap7'
> make[1]: Leaving directory `hello_chap7'
>
> The main function of both example is:
> int main(int argc, char * argv[])
> {
>    const char * salutation = DEFAULT_SALUTATION;
>
> #if HAVE_LTDL_H
>     int ltdl;
>     lt_dlhandle module;
>     get_salutation_t * get_salutation_fp = 0;
>
>     LTDL_SET_PRELOADED_SYMBOLS();
>
>     ltdl = lt_dlinit();
>     if (ltdl == 0)
>     {
>         module = lt_dlopen("modules/hithere/hithere.la");
>         if (module != 0)
>         {
>             get_salutation_fp = (get_salutation_t *) lt_dlsym(module, 
> GET_SALUTATION_SYM);
>             if (get_salutation_fp != 0)
>                 salutation = get_salutation_fp();
>         }
>     }
> #endif
>
> // ...other code
>
>     return 0;
> }
>
> And I saw that in the working example get_salutation_fp is != 0, in my 
> example is not!
>
> Any ideas?
No hints?

--
Alessandro Candini

MEEO S.r.l.
Via Saragat 9
I-44122 Ferrara, Italy
Tel: +39 0532 1861501
Fax: +39 0532 1861637
http://www.meeo.it

========================================
"ATTENZIONE:le informazioni contenute in questo messaggio sono
da considerarsi confidenziali ed il loro utilizzo è riservato unicamente
al destinatario sopra indicato. Chi dovesse ricevere questo messaggio
per errore è tenuto ad informare il mittente ed a rimuoverlo
definitivamente da ogni supporto elettronico o cartaceo."

"WARNING:This message contains confidential and/or proprietary
information which may be subject to privilege or immunity and which
is intended for use of its addressee only. Should you receive this
message in error, you are kindly requested to inform the sender and
to definitively remove it from any paper or electronic format."