Linux loading so files

Loading a linux so file at java runtime

Solution: The windows behaviour is to search for dependent libraries in the directory that the comes from, so when jna loads the library into memory the dependent library is loaded from there as well. You can add an option to the library when building to search in specific locations to find libraries.

Loading a Linux .so File at Java Runtime

Libraries on Linux are often named in the pattern libXXX.so , and I believe Java follows that convention. So System.loadLibrary(«Sample») may be looking for libSample.so . You can verify this by making a quick test program to call System.mapLibraryName and checking the output.

To resolve the issue, assuming this is in fact the problem you’re having, you can either rename your library file or use System.load (not System.loadLibrary ), which will load the library specified by the exact filename you pass it, without any transformations. The latter method is not portable across platforms, though.

Runtime.getRuntime().load(resource); 

I faced the same issue in Linux and solved by setting the LD_LIBRARY_PATH variable

export LD_LIBRARY_PATH=:$LD_LIBRARY_PATH. 

C — cannot open shared object file: No such file or directory, You should add the libbpf library directory to your LD_LIBRARY_PATH variable. $ LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/build/root/usr/lib64

How to add .so file to the java.library.path in Linux

Add the containing directory to LD_LIBRARY_PATH before launching the application

 export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/some/pathOfContainingDirectory 

Use java -XshowSettings:properties to show the java.library.path (and others) value.

I had a lot of trouble figuring this out, please make sure that you have lib prefix in the library name.

1. export LD_LIBRARY_PATH=»$LD_LIBRARY_PATH:/some/pathOfContainingDirectory»
2. Rename libraries to have lib as a prefix. [Add this as part of build script]

mv JNIDemo.so libJNIDemo.so 

Check this answer for detailed explanation https://stackoverflow.com/a/3987567/2076566

I used java -XshowSettings:properties method and found the path of a previously set folder and copied my so file to that folder

Cannot open shared object file: No such file or directory, Your library is a dynamic library. You need to tell the operating system where it can locate it at runtime. To do so, we will need to do those easy steps:.

Load shared library by path at runtime

Un UNIX/Linux systems you can use dlopen . The issue then is you have to fetch all symbols you need via dlsym

typedef int (*some_func)(char *param); void *myso = dlopen("/path/to/my.so", RTLD_NOW); some_func *func = dlsym(myso, "function_name_to_fetch"); func("foo"); dlclose(myso); 

Will load the .so and execute function_name_to_fetch() from in there. See the man page dlopen(1) for more.

On Windows, you can use LoadLibrary , and on Linux, dlopen . The APIs are extremely similar and can load a so/dll directly by providing the full path. That works if it is a run-time dependency (after loading, you «link» by calling GetProcAddress / dlsym .)

I concur with the other posters about the use of dlopen and LoadLibrary. The libltdl gives you a platform-independent interface to these functions.

Java — Running JAR file from terminal (Runtime.getRuntime().exec, You can’t use -jar and -cp at the same time. What you can do, is adding your jar to the classpath and then specify your Main class to run.

Issues loading .so file with JNA in Spring Boot on Linux

The windows behaviour is to search for dependent libraries in the directory that the .dll comes from, so when jna loads the library into memory the dependent library is loaded from there as well.

If you fire up a terminal window and cd to the directory that the .so exists in and run the command:

and it indicates that it’s unable to find the library libCoreGTrans.so then you can see that the search order won’t find this location.

The run-time link-loader ( ld.so ) uses a set of decisions as to where to find libraries. The default behaviour doesn’t include the directory that the library was found.

You can add an option to the library when building to search in specific locations to find libraries. When you’re building the library, you can say to search in the directory that the .so comes from at run time by adding the line:

to the link line. It needs to populate with the constant value $ORIGIN or else this doesn’t work, so this can be a bit tricky to get right in a makefile. This is a value that gets resolved at run-time.

This is all very fine and well if you’re building the library yourself, but if you’re getting libraries from somewhere else, or you’ve already built them and don’t want to rebuild them, you can use a tool such as patchelf to edit the search path for an .so to add it’s origin location:

patchelf --set-rpath '$ORIGIN' libGTransTF.so 

it should be able to successfully find the libCoreGTrans.so library.

Loading a Linux .so File at Java Runtime, load (not System.loadLibrary ), which will load the library specified by the exact filename you pass it, without any transformations. The latter

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How do I load a shared object in C++?

I have a shared object (a so — the Linux equivalent of a Windows dll) that I’d like to import and use with my test code. I’m sure it’s not this simple 😉 but this is the sort of thing I’d like to do..

#include "headerforClassFromBlah.h" int main()

I assume that this is a really basic question but I can’t find anything that jumps out at me searching the web.

Maybe im confused but you don’t look like you have enough info there. What does blah.so contain, for example? You sure you aren’t just talking about using a reference?

Err. so files are not code files, right? Maybe you want to retrieve an object from a .so (shared library) file?

4 Answers 4

There are two ways of loading shared objects in C++

For either of these methods you would always need the header file for the object you want to use. The header will contain the definitions of the classes or objects you want to use in your code.

#include "blah.h" int main() < ClassFromBlah a; a.DoSomething(); >gcc yourfile.cpp -lblah 

#include #include #include int main(int argc, char **argv) < void *handle; double (*cosine)(double); char *error; handle = dlopen ("libm.so", RTLD_LAZY); if (!handle) < fprintf (stderr, "%s\n", dlerror()); exit(1); >dlerror(); /* Clear any existing error */ cosine = dlsym(handle, "cos"); if ((error = dlerror()) != NULL) < fprintf (stderr, "%s\n", error); exit(1); >printf ("%f\n", (*cosine)(2.0)); dlclose(handle); return 0; > 

*Stolen from dlopen Linux man page The process under windows or any other platform is the same, just replace dlopen with the platforms version of dynamic symbol searching.

For the dynamic method to work, all symbols you want to import/export must have extern’d C linkage.

There are some words Here about when to use static and when to use dynamic linking.

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How to install .so file in linux?

In this article, we’ll see how to install the .so file in Linux. To begin with, installing .so files, it’s important to understand what .so file is and how it works. However, if you already have a good understanding of .so files and want to jump straight into the installation process, you can click here.

What are .so files?

A .so file is a type of file in Linux that contains information and functions that one or more programs can use. It’s like a shared resource that several programs can use to perform certain tasks without having to include the same code in their own programs.

.so files are similar to DLL files in Windows and DYLIB files on macOS, but they are specific to Linux-based systems and the Android operating system.

Usage of .so file in Linux

.so files are used in Linux for resource sharing, modular design, faster loading time, improved security, and easy updates. They contain functions and resources that can be shared by multiple programs, making them more efficient and maintainable.

Examples of .so files in Linux

Libc.so, libpthread.so, libssl.so, libpng.so, and libgtk-x11-2.0.so are a few examples of .so files that are frequently used with Linux. Several Linux programs make use of the memory allocation, thread management, SSL encryption, and GUI development functions found in these shared libraries. Different programs may require different shared libraries, depending on their specific needs.

Steps to Install .so file in Linux

The .so file must be manually placed in the proper location for this method to succeed, and ldconfig must be used to update the library cache.

Step 1: Locate The .so File Using pwd Command

The .so file that you want to install must first be located using the pwd command. You may find the file path to the .so file by using this command to print the current working directory. With the cd command, open the terminal and go to the directory containing the .so file. When you are sure you are in the right directory, type pwd to output the directory’s path.

The pwd the command is the alternative command of cwd in window which is used for printing the working directory in the terminal in Linux. So, we will be using it to get the current working directory path, where the .so file exists in the system.

Step 2: Copy The .so File To /usr/local/lib Directory

The next step is to use the cp command with sudo permission to copy the .so file to the /usr/local/lib directory. It is wise to put your .so file in this directory because that is where many Linux applications look for shared libraries.

sudo cp /x/lib.so /usr/local/lib

The `cp` command is used to copy a file/directory to another path of the system. We are using sudo command to gain access to root privileges to copy the lib.so to the /usr/local/lib directory as this is a protected directory and it can’t be modified by a regular (non-root) user.

Step 3: Update The Shared Library Cache Using ldconfig Command

The final step is to update the shared library cache using the ldconfig command with sudo permission. The system’s shared library cache is updated by this command, enabling any applications that rely on the new library to locate it.

And that’s it! The .so file should now be installed and available for use by any application that depends on it.

Conclusion

In conclusion, installing a .so file in Linux is a straightforward process that only requires copying the file to the proper directory and updating the shared library cache. Any application that relies on the .so file can use it once it has been installed. This procedure enables you to quickly add and manage shared libraries in Linux, regardless of whether you’re adding support for a new piece of software or installing a new library for an already-existing application. You can confidently install any necessary .so files on your Linux system and guarantee that they are accessible for use by any application that needs them by carefully following the step-by-step instructions provided in this article.

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