Writing C++ Shared Libraries for Linux

-
I've recently been getting an old Windows-only module cross compiling for Linux. One of the challenges has been figuring out how to make the consuming project find & properly open the .so file. Most posts suggest that you must put your libraries in a specific folder, but a developer friend with stronger Linux kung-fu than mine confirmed that you can simply drop the .so files in the same directory as your application, & consume them using dlopen.

Here's a couple examples: first, a trivial hello world to show the basic consumption, and second, an example of what a reusable interface might look like. The latter shows how to use custom parameter & return types. I am new to designing C interfaces and deploying on Linux, so any comments are welcome.

Hello World from a Linux shared library:

Passing an interface from a Linux shared library:

Comments

Post a Comment

Popular posts from this blog

Fixing Conan Lock Issues

-
I've been implementing Conan as our C++ package manager, and I had the following issue cause me a fair amount of grief over the last couple days: [MyPackageName] is locked by another concurrent conan process, wait... If not the case, quit, and do 'conan remove --locks'  You would be forgiven for thinking conan remove --locks should do the trick, but alas, it does not.  After finding hints on several Conan Github issues, I finally figured out that manually removing the package folders in one or both of the following places will alleviate the issue: Windows : C:\Users\username\.conan\data\packagename WSL/Linux : /home/username/.conan/data/packagename
Read more

Initialize With Care

-
Pointers are funny things.  They are one of the make or break concepts for beginners, and even years later, they can cause grief to experienced developers.  I am no exception.  Here is one such story: I was faced with a class which I wanted to refactor.  It can be simplified as follows: In the interest of breaking up the responsibilities, I added a couple of interfaces. The idea is that I can pass around smart pointers to these interfaces and begin to decouple portions of the code.  For example, I can inject them into classes that need them: However, I made a mistake.  I blame it on years of using boost::intrustive_ptr instead of std::shared_ptr, but enough excuses.  Let's see if you can spot it. Do you see it?  If so, give yourself 5 points.  If not, maybe after seeing the output: 'second' going out of scope... Destructor 'first' going out of scope... 'root' going out of scope... All done... Both shared pointers ( first & second ) are ...
Read more

Permanently Mapping a Windows Share on Linux

-
Every few years, I have to set up a fresh Linux box, and I typically want to connect them to some Windows file shares.  There are many resources on how to do this, but many describe approaches which are incomplete, insecure, or not permanent (across reboots).  Here is what has worked for me. Note: The approach I describe comes from https://wiki.ubuntu.com/MountWindowsSharesPermanently.  I repeat it here because it gets buried in the search results (and I add a few details they gloss over & tweak a few things).  It is worth reading that as well.   Run these commands in order from the console.   Note: The two "nano" commands open a file editor. I have included the necessary file contents below. After updating/creating each of the files, save & exit the editor, and continue with these commands. You should now be able to browse to the local folders you entered in fstab and view the shares.
Read more