Android: dynamic loading shared libraries

2
votes

I have 2 shared libraries: lib1.so and lib2.so.

lib1.so contains some functions which are defined in lib2.so. From a C program I load lib1.so using following call:

dlopen( "lib1.so", RTLD_NOW );

Both libraries are presented in the current directory. My program works under a desktop Linux (Ubuntu, Debian), but not under Android. Under Android dlopen returns an Error and exits. I tried to set:

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:.

but it doesn't help.

I am totally confused, why this code doesn't work under Android. I cannot find any good documentation on Android's dynamic linker. So, I have no explanation why it doesn't work.

DETAILS:

  1. Android with Linux kernel 2.6.35 armv7l
  2. objdump shows lib1.so needs libc.so and lib2.so
  3. objdump shows lib2.so needs only libc.so
3
androidclinuxandroid-ndkshared-libraries

3 Answers

2
votes

Ok. I just found a solution. Adding -lgcc to linker options for lib1.so has solved it. It looks like compiler has auto-generated some calls to special built-in functions from libgcc. It also requires -lc because compiler also auto-generates special calls to memcpy.

1
votes

if dlopen does not work for some reason, have you tried to call dlerror to find out what the real problem is?

0
votes

I not very sure about your project. But I think, it better to load you library from a Service using System.loadLibrary).

System.loadLibrary(lib.so); In your case first load lib2.so and then only load lib1.so