How to get NDK toolchain utilities to list symbols (function names) of NDK-built library on Mac OS X?

Issue

I have a couple of libraries built by the NDK for which I am trying to view the exported symbols, the available function names to be precise. One is a .so file and the other a .a file. I was helped in this question (How to obtain readelf and objdump binaries for OS X?) to find the utilities that I think I need. They are specific to the NDK installation. I am on OS X fyi.

In my NDK installation I found nm and objdump in prebuilt/darwin-x86_64/arm-linux-androideabi/bin. Their file type is "Alias". When I ran nm -g libMylib.so nothing happened -- at all. When I ran objdump -TC libMylib.so I got: "objdump: command not found". Then I found the arm-linux-androideabi-nm and arm-linux-androideabi-objdump files (file type listed as "Unix Executable File" in Finder) in the prebuilt/darwin-x86_64/bin dir. The attempt to use both of them resulted in "command not found". In all these attempts I placed libMylib.so right in the very folder with the utility I'm trying to run.

Solution

I think this is basically a general issue about how to call binaries in unix; even if you are in the same directory when you run nm -g libMylib.so, since . normally isn't part of your $PATH. To run the right one, do ./nm -g libMylib.so, or without using cd to enter this directory first, just do path/to/your/NDK/android-ndk-r10e/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-nm -g libMylib.so, or add this directory to your path first:

export PATH=path/to/your/NDK/android-ndk-r10e/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/bin:$PATH
arm-linux-androideabi-nm -g libMylib.so

(It's preferrable to add this directory to the path instead of the arm-linux-androideabi directory, since it is clear which tool you want to invoke when you call when you do arm-linux-androideabi-nm, while if you add the other directory and call nm, it is up to the order of the directories in $PATH.)

See e.g. Why do you need ./ (dot-slash) before script name to run it in bash? for more explanations about $PATH.

Answered By - mstorsjo