Re: [tpm2] Compiling/linking tpm2 application

* Re: [tpm2] Compiling/linking tpm2 application - undefined reference to Esys function
@ 2019-02-03 15:23 
  0 siblings, 0 replies; 4+ messages in thread
From:  @ 2019-02-03 15:23 UTC (permalink / raw)
  To: tpm2

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Thank you very much it indeed worked!

Is there any special reason for it to have to come after the source files?
I thought that the linker would create the symbols table and add any
"symbol" it finds out so that whenever they are needed they would be
substituted. (in this case, my program would add the "Esys_GetRandom" to
the table and then the linker would check the flag and get the
implementation for that function). I see it doesn't quite work like that,
any special reason or is just my misunderstanding?

Anyway, just to give the whole explanation the complete info of this
problem (if anyone has the same problem)

My gcc command for linking was

"g++ -Wall -g -pthread -std=c++11  -ltss2-esys -L/usr/local/lib/  -o
../../../bin/Developer Developer.o"

When i switched it to

"g++ -Wall -g -pthread -std=c++11 -o ../../../bin/Developer Developer.o
-ltss2-esys -L/usr/local/lib/"

It linked correctly.

Again thank you very much!

Fuchs, Andreas <andreas.fuchs(a)sit.fraunhofer.de> escreveu no dia domingo,
3/02/2019 à(s) 07:23:

> Hi Antonio,
>
> I think we would need to see the complete gcc command.
>
> But maybe a first hint: The -ltss2-esys must come AFTER the source file on
> commandline.
>
> Cheers,
> Andreas
>
> ------------------------------
> *From:* tpm2 [tpm2-bounces(a)lists.01.org] on behalf of António Ribeiro [
> antonio.ribeiro94(a)gmail.com]
> *Sent:* Sunday, February 03, 2019 03:06
> *To:* tpm2(a)lists.01.org
> *Subject:* [tpm2] Compiling/linking tpm2 application - undefined
> reference to Esys function
>
> Hello everyone,
>
> First of all, i am sorry to be bothering this mailing list with a doubt i
> think it should be quite obvious unfortunately, i am not being able to find
> out a solution to it. Also, i am not sure if this should go here or in the
> issues of the repositories. If this is not the right place i will gladly
> post it on github.
>
> I installed everything as said in github repos (tpm2-tss, tpm2-abrmd and
> tpm2-tools). I am trying to create an application (just a proof of concept)
> with tpm2 and the first thing i am trying to do is call a function from the
> library Esys (tss2/tss2_esys.h) to print a random number. Unfortunately,
> when i try to compile and link the application files the compiler/linker
> (gcc) says:
>
> *(if it is needed i can copy/paste the whole text)*
> *"undefined reference to `Esys_GetRandom'"*
>
> On the code, i am trying to make the same call that is made on tpm2-tools
> getrandom, so i dont think there is a problem with that call (and also it
> compiles correctly but doesn't link).
>
> I am using the flags i suppose are needed "-I/usr/local/include" for
> compilation (just to be sure) and "-L/usr/local/lib -ltss2-mu
> -ltss2-tcti-device -ltss2-sys -ltss2-esys" for the linking part (i also
> tried with the flags "-ltpm2sapi" which i found in another github repo. I
> was able to compile and use all the tools on the tpm2-tools repo, which
> makes me believe the problem is not in the libraries themselves but  any
> flags may be missing in my linking. Unfortunately, i tried with the flags i
> could get from the Makefile it has on tpm2-tools but same result.
>
> Can anyone tell me what am i doing wrong? Or at least point me in the
> right direction?
> The OS is Ubuntu 18.04.1 LTS (in VMWare Workstation if it makes any
> difference).
>
> Thank you very much;
>
> --
> António Ribeiro
> +351 916045500 | antonio.ribeiro94(a)gmail.com
> Masters in Computer Science & Engineering
> New University of Lisbon - Faculty of Science and Technology
>

-- 
António Ribeiro
+351 916045500 | antonio.ribeiro94(a)gmail.com
Masters in Computer Science & Engineering
New University of Lisbon - Faculty of Science and Technology

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