Error in linking while creating a shared library of AES C file

Question

Encountering error while creating a shared library of AES. The following commands are used :

gcc -Wall Test1.c x64/libSESDAPI.a -fPIC -lssl -lcrypto

gcc -shared -o libfile.so a.out -nostartfiles

And I am getting the following errors:

/usr/bin/ld: error in a.out(.eh_frame); no .eh_frame_hdr table will be created.

/usr/bin/ld: libfile.so: No symbol version section for versioned symbol `AES_cbc_encrypt@@OPENSSL_1.0.0'

/usr/bin/ld: final link failed: Nonrepresentable section on output collect2: error: ld returned 1 exit status

I am new to shared libraries so please help.

Edit: I have edited and added the lcrypto and lssl

Edit2: By adding a -c in the first command, the above errors are now resolved. But now accessing the .so file with python gives a new error

OSError: ./libfile.so: undefined symbol: SDSCListDevs

Please tell why this error is coming.

By the way, this question and all your problems would have been solved by [a very simple search](https://www.google.se/search?q=how+to+create+shared+library+in+linux). — Some programmer dude, Mar 14 '17 at 15:23

Some programmer dude · Accepted Answer · 2017-03-14T15:21:32.157

1

You should be creating your shared library from an object file, not from an executable program.

You also need to link with the SSL libraries.

Commands to use:

# Compile the source file, generate object file
gcc -Wall Test1.c -c -fPIC

# Link object file with libraries to create the shared object
gcc -shared -fPIC -o libfile.so Test1.o x64/libSESDAPI.a -lssl -lcrypto

edited Mar 14 '17 at 15:21

answered Mar 14 '17 at 14:46

Some programmer dude

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object file is not being generated. Only a.out file is generated – Sarang S. Chaturvedi Mar 14 '17 at 14:52
@SarangS.Chaturvedi You have to add the `-c` option when compiling your source file. – Some programmer dude Mar 14 '17 at 14:54
It is written that -c option which makes the compiler only compile the source and not link. When using the shared library so formed with -c it gives only ET_DYN and ET_EXEC can be loaded. Please suggest.Thanks in advance @Some programmer dude – Sarang S. Chaturvedi Mar 14 '17 at 15:08
@SarangS.Chaturvedi I said use `-c` ***when compiling***, not when linking. I'll update my answer to show the commands (didn't think it would be necessary!) – Some programmer dude Mar 14 '17 at 15:12
I have edited the question. Please see to it. – Sarang S. Chaturvedi Mar 14 '17 at 15:18
@SarangS.Chaturvedi And you link with the libraries when creating the `libfile.so` shared object? – Some programmer dude Mar 14 '17 at 15:18
@SarangS.Chaturvedi Oh and have the files for the static library `libSESDAPI.a` been compiled with `-fPIC`? And you need `-fPIC` when linking too I think (added it in my answer) – Some programmer dude Mar 14 '17 at 15:20
I have found that the main error after doing whatever you suggested is not the inclusion of SDSCDev.h header file in the AES.c that is being compiled. So please if you can suggest anything. – Sarang S. Chaturvedi Mar 14 '17 at 16:56

Error in linking while creating a shared library of AES C file

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