Struct dlopen::raw::Library

pub struct Library { /* fields omitted */ }

Main interface for opening and working with a dynamic link library.

Note: Several methods have their “_cstr” equivalents. This is because all native OS interfaces actually use C-strings. If you pass CStr as an argument, Library doesn’t need to perform additional conversion from Rust string to C-string.. This makes `_cstr“ functions slightly more optimal than their normal equivalents. It is recommended that you use const-cstr crate to create statically allocated C-strings.

Note: The handle to the library gets released when the library object gets dropped. Unless your application opened the library multiple times, this is the moment when symbols obtained from the library become dangling symbols.

Implementations

impl Library

pub fn open<S>(name: S) -> Result<Library, Error> where
    S: AsRef<OsStr>, 

Open a dynamic library.

Note: different platforms search for libraries in different directories. Therefore this function cannot be 100% platform independent. However it seems that all platforms support the full path and searching in default os directories if you provide only the file name. Please refer to your operating system guide for precise information about the directories where the operating system searches for dynamic link libraries.

Example

extern crate dlopen;
use dlopen::raw::Library;

fn main() {
    //use full path
    let lib = Library::open("/lib/i386-linux-gnu/libm.so.6").unwrap();
    //use only file name
    let lib = Library::open("libm.so.6").unwrap();
}

pub fn open_self() -> Result<Library, Error>

Open the main program itself as a library.

This allows a shared library to load symbols of the program it was loaded into.

pub unsafe fn symbol<T>(&self, name: &str) -> Result<T, Error>

Obtain symbol from opened library.

Note: the T template type needs to have a size of a pointer. Because Rust does not support static casts at the moment, the size of the type is checked in runtime and causes panic if it doesn’t match.

Note: It is legal for a library to export null symbols. However this is something that almost nobody expects. Therefore allowing it here would bring many problems, especially if user obtains references or functions. This method checks the address value and returns Error::NullSymbol error if the value is null. If your code does require obtaining symbols with null value, please do something like this:

Example

extern crate dlopen;
use dlopen::raw::Library;
use dlopen::Error;
use std::ptr::null;
fn main(){
    let lib = Library::open("libyourlib.so").unwrap();
    let ptr_or_null: * const i32 = match unsafe{ lib.symbol("symbolname") } {
        Ok(val) => val,
        Err(err) => match err {
            Error::NullSymbol => null(),
            _ => panic!("Could not obtain the symbol")
        }
    };
    //do something with the symbol
}

pub unsafe fn symbol_cstr<T>(&self, name: &CStr) -> Result<T, Error>

Equivalent of the symbol method but takes CStr as a argument.

Trait Implementations

impl Debug for Library

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Drop for Library

fn drop(&mut self)

Executes the destructor for this type.

impl Send for Library

impl Sync for Library