How can I change the filename of a shared library after building a program that depends on it?
We can use patchelf:
patchelf --replace-needed liboriginal.so.1 libreplacement.so.1 my-program
We can also remove a dependency:
patchelf --remove-needed libfoo.so.1 my-program
Add a dependency:
patchelf --add-needed libfoo.so.1 my-program
Or change the path where to search for the libraries (rpath):
patchelf --set-rpath /path/to/lib:/other/path my-program
Posting a tentative, horrible, hacky solution.
The library dependencies are stored in an ELF block known as the .depends block. The format of that block is a large array of identifier/stringpointer pairs, with the stringpointer pointing to a standard C null-terminated string located somewhere in the binary.
You see where this is going, right?
Yep, as long as the new path you need is no larger than the old path, you can just reach right into the binary and do a simple string replace. Make sure not to add or remove bytes or you'll break the entire binary. If you want to be safer about it, you could actually traverse the ELF structure to ensure you had the right location - right now I'm just checking to make sure the source string shows up exactly once.
ELF does include a checksum, but apparently there's no loader that actually verifies it, so it's "safe" - albeit messy - to ignore.
The "real solution" would be a utility that allowed low-level generalized manipulations of the ELF structure. As near as I can tell, no such utility exists, for anything except a few specialized cases (RPATH, mostly.) I don't pretend to know how difficult such a utility would be to write.
I would absolutely love a better solution to this, but, so far, this appears to work.
HT - this might be helpful.
HT is a file editor/viewer/analyzer for executables. The goal is to combine the low-level functionality of a debugger and the usability of IDEs. We plan to implement all (hex-)editing features and support of the most important file formats.
I couldn't find something much different from ZorbaTHut's solution, but perhaps it's possible to put a name with different length and still keep the binary valid.
gelf - this could be useful too.
GElf is a generic, ELF class-independent API for manipulat- ing ELF object files. GElf provides a single, common inter- face for handling 32-bit and 64-bit ELF format object files.