Dylib - C++ cross-platform dynamic library loader

The goal of this C++ library is to load dynamic libraries (.so, .dll, .dylib) and access its functions and global variables at runtime.

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Compatibility

Works on Linux, Windows, MacOS

Installation

You can fetch dylib to your project using CMake:

include(FetchContent)

FetchContent_Declare(
    dylib
    GIT_REPOSITORY "https://github.com/martin-olivier/dylib"
    GIT_TAG        "v1.8.3"
)

FetchContent_MakeAvailable(dylib)

You can also click HERE to download the dylib header file.

Documentation

Dylib class

The dylib class can load a dynamic library at runtime:

dylib lib("./dynamic_lib.so");

The dylib class can detect the file extension of the actual os using dylib::extension:

dylib lib("./dynamic_lib", dylib::extension);

or

dylib lib;
lib.open("./dynamic_lib", dylib::extension);

Open and close

open
Load a dynamic library into the object. If a dynamic library was already opened, it will be unloaded and replaced

close
Unload the dynamic library currently loaded in the object. This function will be automatically called by the class destructor

// Load ./dynamic_lib.so

dylib lib("./dynamic_lib.so");

// Unload ./dynamic_lib.so and load ./other_dynamic_lib.so

lib.open("./other_dynamic_lib.so");

// Unload ./other_dynamic_lib.so

lib.close();

Get a function or a variable

get_function
Get a function from the dynamic library currently loaded in the object

get_variable
Get a global variable from the dynamic library currently loaded in the object

// Load ./dynamic_lib.so

dylib lib("./dynamic_lib.so");

// Get the function adder (get_function<T> will return std::function<T>)

auto adder = lib.get_function<double(double, double)>("adder");

// Get the global variable pi_value

const double &pi = lib.get_variable<double>("pi_value");

// Use the function adder with pi_value

double result = adder(pi, pi);

Miscellaneous tools

operator bool
Returns true if a dynamic library is currently loaded in the object, false otherwise

has_symbol
Returns true if the symbol passed as parameter exists in the dynamic library, false otherwise

native_handle
Returns the dynamic library handle

void example(dylib &lib)
{
    if (lib)
        std::cout << "Something is currently loaded in the dylib object" << std::endl;

    if (lib.has_symbol("GetModule"))
        std::cout << "GetModule symbol has been found" << std::endl;

    dylib::native_handle_type handle = lib.native_handle();
}

Dylib exceptions

handle_error
This exception is raised when the library failed to load or the library encountered symbol resolution issues

symbol_error
This exception is raised when the library failed to load a symbol. This usually happens when you forgot to put DYLIB_API before a library function or variable

Those exceptions inherit from dylib::exception

try {
    dylib lib("./dynamic_lib.so");
    const double &pi_value = lib.get_variable<double>("pi_value");
    std::cout << pi_value << std::endl;
}
catch (const dylib::exception &e) {
    std::cerr << e.what() << std::endl;
    return EXIT_FAILURE;
}
return EXIT_SUCCESS;

Example

A full example about the usage of the dylib library is available HERE

Tips

Remove the lib prefix

If you use CMake to build a dynamic library, running the below CMake rule will allow you to remove the prefix lib for macOS and linux, ensuring that the library shares the same name on all the different OS:

set_target_properties(target PROPERTIES PREFIX "")

	Without CMake rule	With CMake rule
Linux	libmalloc.so	malloc.so
MacOS	libmalloc.dylib	malloc.dylib
Windows	malloc.dll	malloc.dll

Build and run unit tests

To build the unit tests, enter the following commands:

cmake . -B build -DBUILD_TESTS=ON
cmake --build build

To run the unit tests, enter the following command:

# on unix
./unit_tests

# on windows, in "Debug" folder
./unit_tests.exe