https://github.com/calebmadrigal/static-shared-lib

An example of how to statically compile a shared linux library (.so).
https://github.com/calebmadrigal/static-shared-lib

Last synced: about 1 month ago
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An example of how to statically compile a shared linux library (.so).

• Host: GitHub
• URL: https://github.com/calebmadrigal/static-shared-lib
• Owner: calebmadrigal
• License: mit
• Created: 2016-02-09T23:03:18.000Z (almost 9 years ago)
• Default Branch: master
• Last Pushed: 2016-02-10T17:37:30.000Z (almost 9 years ago)
• Last Synced: 2024-04-15T06:53:53.402Z (7 months ago)
• Language: Makefile
• Size: 146 KB
• Stars: 5
• Watchers: 3
• Forks: 6
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# static-shared-lib-example

An example of how to build a statically-linked shared (dynamic) linux library (.so).

Things to note:

* `do_test.main()` calls `libtestlib.do_test()` which calls `testlib2.square()`.

* `libtestlib.so` is statically compiled. It relies on `testlib2.o` for the `square()` function.

* Since `testlib.so` is statically compiled, we can delete `testlib2.o` and `do_test` still runs.

My goal was to have `testlib2` be a normal dynamic library (`.so`), however, I was unable to statically compile it into `libtestlib.so` without changing how testlib2 was compiled, so that it is just an unlinked object file.

### Usage

Build it:

    make

Run it:

    make test

This deletes `testlib2.o` and runs `do_test`.

### Seeing the static linking

You can see that `libtestlib.so` is statically linked against `testlib2.o` by running `ldd`:

    $ ldd libtestlib.so

        linux-vdso.so.1 =>  (0x00007fffa2ffc000)

        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f23e0a52000)

        /lib64/ld-linux-x86-64.so.2 (0x00007f23e1034000)

Also, note, however, that `testlib.so` is dynamically linked against glibc and a couple other libraries.

### Disassembly

I opened `libtestlib.so` in [Hopper disassembler](http://www.hopperapp.com/), and was able to see the `square` function from `testlib2.o` in it (along side `do_test`):

![libtestlib.so disassembled](https://raw.githubusercontent.com/calebmadrigal/static-shared-lib/master/testlib-so-disassembled.png)