Is it possible to change shared library references in a shared object file?

Question

I have a .so file which contains a reference to /Library/Frameworks/Python.framework/Versions/2.7/Python (I can see this path hard-coded in plaintext within the .so file). I don't have access to the source that built the .so file.

I'd like to use a different version of the python library (stored in /opt/local/Library). Is it possible to edit the .so file to reassign this path?

Answer 1

You may be able to permanently change the reference by using install_name_tool included with OS X Xcode command line tools.

install_name_tool -change old-lib-path new-lib-path path-to.so

However, if new-path is longer than the original old-path, there may not be room in the field in the bundle file (.so) to do so. The man page for install_name_tool cautions:

For this tool to work when the install names or rpaths are larger the binary should be built with the ld(1) -headerpad_max_install_names option.

Also, there is no guarantee that the new Python you wish to use was built in a way that is compatible with the old shared library expected by the .so you are trying to modify. There may be differences in universal CPU architectures, OS X deployment targets, and Python build options (for example, UCS-2 vs UCS-4) that may preclude success. You should make a copy of the .so before attempting to modify it.