g++ not find .so files

Question

I am trying to generate a c++ library using the g++ compiler. My library has another C library as dependency and I have compiled it in order to obtain the .so files.

I have the following structure:

src:
    include/linux:
        libcustom.a
        libcustom.la
        libcustom.so
        libcustom.so.0
        libcustom.so.0.0.0

Now, when I have all the .o files of my cpp classes, and I want to link the library, I execute the following command:

g++ -shared -L/usr/lib/R/lib -Wl,-Bsymbolic-functions -Wl,-z,relro -o mylibrary.so File1.o File2.o File3.o -L./include/linux -lc++ -lutil -lm -lcustom -Wl,-rpath='$ORIGIN/include/linux' -L/usr/lib/R/lib -lR

But it throws me the error:

libcustom.so.0: cannot open shared object file: No such file or directory

I am executing the command from the src directory.

I know it could be fixed editing the LD_LIBRARY_PATH, but the idea it is someone can use my library without the need of configuring anything, so I am trying to do that with the c++'s -rpath flag.

Any idea how can I fix it, or the reason for the error?

You use relative path `-Wl,-rpath=./include/linux`, which is not recognized by the `ld` loader in Linux. Use absolute path instead. For correct way of using relative path, goto http://stackoverflow.com/a/4018559/6238076 — gdlmx, May 14 '16 at 11:25

score 3 · Answer 1 · edited May 23 '17 at 12:09

3

The error message you got seems to come from the run-time loader ld.so instead of the linker ld (I know the names are confusing). You have to distinguish between finding so's at link-time and at run-time. The -L flag you give at link-time has nothing to do with localizing the library at run-time.

Your rpath=./include/linux value is not correct, because dot is not recognized by the ld as relative path. Relative searching path should be given like

-Wl,-rpath='$ORIGIN/include/linux'

where the $ORIGIN represents the folder where your executable (not mylibrary.so) locates. Make sure to use single quote and not double quote because the string $ORIGIN should be passed to the linker literally and hard coded into the executable file.

More details goes

edited May 23 '17 at 12:09

Community

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answered May 14 '16 at 11:43

gdlmx

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You are totally right, that is the problem, because now I have tested to change the -rpath indicating the absolute path of the library and it works. But `$ORIGIN` does not work for me, because I am using a Makevars file and it "translates" the -rpath from `-Wl,-rpath="'$$ORIGIN/include/linux'"` to `-Wl,-rpath="'/include/linux'"`. I have read the webpage attached in the post that you suggest, and I can not find the solution. Do you know how can I fix it? Thank you very much – bra_racing May 14 '16 at 13:14
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In Makefile you need to escape the `$` symbol with `$$`: that is `-rpath='$$ORIGIN/include/linux'` – gdlmx May 14 '16 at 13:17
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Also you don't need to double quote the path, use single quote only. Check the echo of your make command and ensure the parameter is passed to g++ correctly – gdlmx May 14 '16 at 13:26
Now I have written `-rpath='$$ORIGIN/include/linux'` in my Makevars, and it executes `-rpath=$ORIGIN/include/linux` without the quotes. How can add them? If I write `-rpath="'$$ORIGIN/include/linux"'` (double quotes plus single quotes) it executes `rpath=/include/linux` – bra_racing May 14 '16 at 13:28
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Seems that you need to write `'-Wl,-rpath=\'$$ORIGIN/include/linux\''` to also escape single quote `'`. http://stackoverflow.com/a/7860705/6238076 – gdlmx May 14 '16 at 13:36
With `'-Wl,-rpath='\''$$ORIGIN/include/linux'\'''` it executes `'$ORIGIN/include/linux'` (great!), but still throwing the error because it does not find the `.so` file. Do I need to configure something else in order to use the $ORIGIN param? Sorry if I am annoying you, I appreciate a lot your help – bra_racing May 14 '16 at 13:58
Can you update the question including the echo of your make system (exact commands issued to g++ and the corresponding error message). – gdlmx May 14 '16 at 17:17
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/111941/discussion-between-gdlmx-and-bra-racing). – gdlmx May 14 '16 at 17:29

g++ not find .so files

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