1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320
#[cfg(libloading_docs)]
use super::os::unix as imp; // the implementation used here doesn't matter particularly much...
#[cfg(all(not(libloading_docs), unix))]
use super::os::unix as imp;
#[cfg(all(not(libloading_docs), windows))]
use super::os::windows as imp;
use super::Error;
use std::ffi::OsStr;
use std::fmt;
use std::marker;
use std::ops;
use std::os::raw;
/// A loaded dynamic library.
#[cfg_attr(libloading_docs, doc(cfg(any(unix, windows))))]
pub struct Library(imp::Library);
impl Library {
/// Find and load a dynamic library.
///
/// The `filename` argument may be either:
///
/// * A library filename;
/// * The absolute path to the library;
/// * A relative (to the current working directory) path to the library.
///
/// # Safety
///
/// When a library is loaded, initialisation routines contained within it are executed.
/// For the purposes of safety, the execution of these routines is conceptually the same calling an
/// unknown foreign function and may impose arbitrary requirements on the caller for the call
/// to be sound.
///
/// Additionally, the callers of this function must also ensure that execution of the
/// termination routines contained within the library is safe as well. These routines may be
/// executed when the library is unloaded.
///
/// # Thread-safety
///
/// The implementation strives to be as MT-safe as sanely possible, however on certain
/// platforms the underlying error-handling related APIs not always MT-safe. This library
/// shares these limitations on those platforms. In particular, on certain UNIX targets
/// `dlerror` is not MT-safe, resulting in garbage error messages in certain MT-scenarios.
///
/// Calling this function from multiple threads is not MT-safe if used in conjunction with
/// library filenames and the library search path is modified (`SetDllDirectory` function on
/// Windows, `{DY,}LD_LIBRARY_PATH` environment variable on UNIX).
///
/// # Platform-specific behaviour
///
/// When a plain library filename is supplied, the locations in which the library is searched are
/// platform specific and cannot be adjusted in a portable manner. See the documentation for
/// the platform specific [`os::unix::Library::new`] and [`os::windows::Library::new`] methods
/// for further information on library lookup behaviour.
///
/// If the `filename` specifies a library filename without a path and with the extension omitted,
/// the `.dll` extension is implicitly added on Windows.
///
/// [`os::unix::Library::new`]: crate::os::unix::Library::new
/// [`os::windows::Library::new`]: crate::os::windows::Library::new
///
/// # Tips
///
/// Distributing your dynamic libraries under a filename common to all platforms (e.g.
/// `awesome.module`) allows you to avoid code which has to account for platform’s conventional
/// library filenames.
///
/// Strive to specify an absolute or at least a relative path to your library, unless
/// system-wide libraries are being loaded. Platform-dependent library search locations
/// combined with various quirks related to path-less filenames may cause flakiness in
/// programs.
///
/// # Examples
///
/// ```no_run
/// # use ::libloading::Library;
/// // Any of the following are valid.
/// unsafe {
/// let _ = Library::new("/path/to/awesome.module").unwrap();
/// let _ = Library::new("../awesome.module").unwrap();
/// let _ = Library::new("libsomelib.so.1").unwrap();
/// }
/// ```
pub unsafe fn new<P: AsRef<OsStr>>(filename: P) -> Result<Library, Error> {
imp::Library::new(filename).map(From::from)
}
/// Get a pointer to a function or static variable by symbol name.
///
/// The `symbol` may not contain any null bytes, with the exception of the last byte. Providing a
/// null-terminated `symbol` may help to avoid an allocation.
///
/// The symbol is interpreted as-is; no mangling is done. This means that symbols like `x::y` are
/// most likely invalid.
///
/// # Safety
///
/// Users of this API must specify the correct type of the function or variable loaded.
///
/// # Platform-specific behaviour
///
/// The implementation of thread-local variables is extremely platform specific and uses of such
/// variables that work on e.g. Linux may have unintended behaviour on other targets.
///
/// On POSIX implementations where the `dlerror` function is not confirmed to be MT-safe (such
/// as FreeBSD), this function will unconditionally return an error when the underlying `dlsym`
/// call returns a null pointer. There are rare situations where `dlsym` returns a genuine null
/// pointer without it being an error. If loading a null pointer is something you care about,
/// consider using the [`os::unix::Library::get_singlethreaded`] call.
///
/// [`os::unix::Library::get_singlethreaded`]: crate::os::unix::Library::get_singlethreaded
///
/// # Examples
///
/// Given a loaded library:
///
/// ```no_run
/// # use ::libloading::Library;
/// let lib = unsafe {
/// Library::new("/path/to/awesome.module").unwrap()
/// };
/// ```
///
/// Loading and using a function looks like this:
///
/// ```no_run
/// # use ::libloading::{Library, Symbol};
/// # let lib = unsafe {
/// # Library::new("/path/to/awesome.module").unwrap()
/// # };
/// unsafe {
/// let awesome_function: Symbol<unsafe extern fn(f64) -> f64> =
/// lib.get(b"awesome_function\0").unwrap();
/// awesome_function(0.42);
/// }
/// ```
///
/// A static variable may also be loaded and inspected:
///
/// ```no_run
/// # use ::libloading::{Library, Symbol};
/// # let lib = unsafe { Library::new("/path/to/awesome.module").unwrap() };
/// unsafe {
/// let awesome_variable: Symbol<*mut f64> = lib.get(b"awesome_variable\0").unwrap();
/// **awesome_variable = 42.0;
/// };
/// ```
pub unsafe fn get<'lib, T>(&'lib self, symbol: &[u8]) -> Result<Symbol<'lib, T>, Error> {
self.0.get(symbol).map(|from| Symbol::from_raw(from, self))
}
/// Unload the library.
///
/// This method might be a no-op, depending on the flags with which the `Library` was opened,
/// what library was opened or other platform specifics.
///
/// You only need to call this if you are interested in handling any errors that may arise when
/// library is unloaded. Otherwise the implementation of `Drop` for `Library` will close the
/// library and ignore the errors were they arise.
///
/// The underlying data structures may still get leaked if an error does occur.
pub fn close(self) -> Result<(), Error> {
self.0.close()
}
}
impl fmt::Debug for Library {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.0.fmt(f)
}
}
impl From<imp::Library> for Library {
fn from(lib: imp::Library) -> Library {
Library(lib)
}
}
impl From<Library> for imp::Library {
fn from(lib: Library) -> imp::Library {
lib.0
}
}
unsafe impl Send for Library {}
unsafe impl Sync for Library {}
/// Symbol from a library.
///
/// This type is a safeguard against using dynamically loaded symbols after a `Library` is
/// unloaded. The primary method to create an instance of a `Symbol` is via [`Library::get`].
///
/// The `Deref` trait implementation allows the use of `Symbol` as if it was a function or variable
/// itself, without taking care to “extract” the function or variable manually most of the time.
///
/// [`Library::get`]: Library::get
#[cfg_attr(libloading_docs, doc(cfg(any(unix, windows))))]
pub struct Symbol<'lib, T: 'lib> {
inner: imp::Symbol<T>,
pd: marker::PhantomData<&'lib T>,
}
impl<'lib, T> Symbol<'lib, T> {
/// Extract the wrapped `os::platform::Symbol`.
///
/// # Safety
///
/// Using this function relinquishes all the lifetime guarantees. It is up to the developer to
/// ensure the resulting `Symbol` is not used past the lifetime of the `Library` this symbol
/// was loaded from.
///
/// # Examples
///
/// ```no_run
/// # use ::libloading::{Library, Symbol};
/// unsafe {
/// let lib = Library::new("/path/to/awesome.module").unwrap();
/// let symbol: Symbol<*mut u32> = lib.get(b"symbol\0").unwrap();
/// let symbol = symbol.into_raw();
/// }
/// ```
pub unsafe fn into_raw(self) -> imp::Symbol<T> {
self.inner
}
/// Wrap the `os::platform::Symbol` into this safe wrapper.
///
/// Note that, in order to create association between the symbol and the library this symbol
/// came from, this function requires a reference to the library.
///
/// # Safety
///
/// The `library` reference must be exactly the library `sym` was loaded from.
///
/// # Examples
///
/// ```no_run
/// # use ::libloading::{Library, Symbol};
/// unsafe {
/// let lib = Library::new("/path/to/awesome.module").unwrap();
/// let symbol: Symbol<*mut u32> = lib.get(b"symbol\0").unwrap();
/// let symbol = symbol.into_raw();
/// let symbol = Symbol::from_raw(symbol, &lib);
/// }
/// ```
pub unsafe fn from_raw<L>(sym: imp::Symbol<T>, library: &'lib L) -> Symbol<'lib, T> {
let _ = library; // ignore here for documentation purposes.
Symbol {
inner: sym,
pd: marker::PhantomData,
}
}
/// Try to convert the symbol into a raw pointer.
/// Success depends on the platform. Currently, this fn always succeeds and returns some.
///
/// # Safety
///
/// Using this function relinquishes all the lifetime guarantees. It is up to the developer to
/// ensure the resulting `Symbol` is not used past the lifetime of the `Library` this symbol
/// was loaded from.
pub unsafe fn try_as_raw_ptr(self) -> Option<*mut raw::c_void> {
Some(
#[allow(unused_unsafe)] // 1.56.0 compat
unsafe {
// SAFE: the calling function has the same soundness invariants as this callee.
self.into_raw()
}
.as_raw_ptr(),
)
}
}
impl<'lib, T> Symbol<'lib, Option<T>> {
/// Lift Option out of the symbol.
///
/// # Examples
///
/// ```no_run
/// # use ::libloading::{Library, Symbol};
/// unsafe {
/// let lib = Library::new("/path/to/awesome.module").unwrap();
/// let symbol: Symbol<Option<*mut u32>> = lib.get(b"symbol\0").unwrap();
/// let symbol: Symbol<*mut u32> = symbol.lift_option().expect("static is not null");
/// }
/// ```
pub fn lift_option(self) -> Option<Symbol<'lib, T>> {
self.inner.lift_option().map(|is| Symbol {
inner: is,
pd: marker::PhantomData,
})
}
}
impl<'lib, T> Clone for Symbol<'lib, T> {
fn clone(&self) -> Symbol<'lib, T> {
Symbol {
inner: self.inner.clone(),
pd: marker::PhantomData,
}
}
}
// FIXME: implement FnOnce for callable stuff instead.
impl<'lib, T> ops::Deref for Symbol<'lib, T> {
type Target = T;
fn deref(&self) -> &T {
ops::Deref::deref(&self.inner)
}
}
impl<'lib, T> fmt::Debug for Symbol<'lib, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.inner.fmt(f)
}
}
unsafe impl<'lib, T: Send> Send for Symbol<'lib, T> {}
unsafe impl<'lib, T: Sync> Sync for Symbol<'lib, T> {}