CODEWITHSUNDEEP
linuxgcclinkerstatic-libraries
Aftnix
Aftnix

Reputation: 4599

Static Linking dependencies

I'm trying to build a app which is linked against a bunch of static and shared libraries. Which is done by following command :

arif@khost:~/sak/pjsip$ gcc -v -o /home/arif/pjsip-samples/sample_apps/playfile.out pjsip-apps/src/samples/playfile.o `pkg-config --libs libpjproject`

Where pkg-config --libs libpjproject spits out :

    arif@khost:~/sak/pjsip$ pkg-config --libs libpjproject
    -pthread -L/opt/pjsip/lib -L/opt/ffmpeg/lib -lpjmedia-videodev-x86_64-unknown-linux-gnu -lpjmedia-audiodev-x86_64-unknown-linux-gnu -lpjmedia-x86_64-unknown-linux-gnu
............(other libraries are omitted)

The relevant libraries are [1]pjmedia-audiodev [2]`pjmedia

The linking error which is reported here : 

/opt/pjsip/lib/libpjmedia-x86_64-unknown-linux-gnu.a(endpoint.o): In function `pjmedia_endpt_create':
endpoint.c:(.text+0x14f): undefined reference to `pjmedia_aud_subsys_init'
endpoint.c:(.text+0x1b0): undefined reference to `pjmedia_aud_subsys_shutdown'(etc)

Now it should not be the case because :

arif@khost:~/sak/pjsip$ nm /opt/pjsip/lib/libpjmedia-x86_64-unknown-linux-gnu.a | grep pjmedia_aud_subsys
                 U pjmedia_aud_subsys_init
                 U pjmedia_aud_subsys_shutdown
                 U pjmedia_aud_subsys_get_pool_factory
                 U pjmedia_aud_subsys_init
                 U pjmedia_aud_subsys_shutdown

`

I'm aware of the fact that linking order is very important for shared libraries, I thought it should not be the case because we are copying the object file anyway.

Am i missing something?

UPDATE 1

My bad, The symbol is not in pjmedia but in pjmedia-auddev :

arif@khost:/opt/pjsip/lib$ nm -C libpjmedia-audiodev-x86_64-unknown-linux-gnu.a | grep pjmedia_aud_subsys_init
0000000000000720 T pjmedia_aud_subsys_init

So there is clearly linking order problem here. Because libpjmedia using libpjmedia-auddev but in command line its given in wrong order.

The problem is solved if i take libpjmedia before libpjmedia-auddev.

Upvotes: 1

Views: 1007

Answers (2)

Daniel Fussia
Daniel Fussia

Reputation: 1

You need -lpjmedia-x86_64-unknown-linux-gnu before -lpjmedia-videodev-x86_64-unknown-linux-gnu inclusion.

Upvotes: 0

Michael Pankov
Michael Pankov

Reputation: 3701

         U pjmedia_aud_subsys_init

U in this output means that the symbol is undefined. When it's defined in this library, this column of output should have t or T, and address of the symbol is output on the left.

You should find the library which actually defines these symbols and add it to command line.

Upvotes: 2

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