| //! Used by `rustc` when loading a plugin. |
| |
| use crate::errors::{LoadPluginError, MalformedPluginAttribute}; |
| use crate::Registry; |
| use libloading::Library; |
| use rustc_ast::Attribute; |
| use rustc_metadata::locator; |
| use rustc_session::cstore::MetadataLoader; |
| use rustc_session::Session; |
| use rustc_span::symbol::{sym, Ident}; |
| |
| use std::env; |
| use std::mem; |
| use std::path::PathBuf; |
| |
| /// Pointer to a registrar function. |
| type PluginRegistrarFn = fn(&mut Registry<'_>); |
| |
| /// Read plugin metadata and dynamically load registrar functions. |
| pub fn load_plugins( |
| sess: &Session, |
| metadata_loader: &dyn MetadataLoader, |
| attrs: &[Attribute], |
| ) -> Vec<PluginRegistrarFn> { |
| let mut plugins = Vec::new(); |
| |
| for attr in attrs { |
| if !attr.has_name(sym::plugin) { |
| continue; |
| } |
| |
| for plugin in attr.meta_item_list().unwrap_or_default() { |
| match plugin.ident() { |
| Some(ident) if plugin.is_word() => { |
| load_plugin(&mut plugins, sess, metadata_loader, ident) |
| } |
| _ => { |
| sess.emit_err(MalformedPluginAttribute { span: plugin.span() }); |
| } |
| } |
| } |
| } |
| |
| plugins |
| } |
| |
| fn load_plugin( |
| plugins: &mut Vec<PluginRegistrarFn>, |
| sess: &Session, |
| metadata_loader: &dyn MetadataLoader, |
| ident: Ident, |
| ) { |
| let lib = locator::find_plugin_registrar(sess, metadata_loader, ident.span, ident.name); |
| let fun = dylink_registrar(lib).unwrap_or_else(|err| { |
| // This is fatal: there are almost certainly macros we need inside this crate, so |
| // continuing would spew "macro undefined" errors. |
| sess.emit_fatal(LoadPluginError { span: ident.span, msg: err.to_string() }); |
| }); |
| plugins.push(fun); |
| } |
| |
| /// Dynamically link a registrar function into the compiler process. |
| fn dylink_registrar(lib_path: PathBuf) -> Result<PluginRegistrarFn, libloading::Error> { |
| // Make sure the path contains a / or the linker will search for it. |
| let lib_path = env::current_dir().unwrap().join(&lib_path); |
| |
| let lib = unsafe { Library::new(&lib_path) }?; |
| |
| let registrar_sym = unsafe { lib.get::<PluginRegistrarFn>(b"__rustc_plugin_registrar") }?; |
| |
| // Intentionally leak the dynamic library. We can't ever unload it |
| // since the library can make things that will live arbitrarily long |
| // (e.g., an Rc cycle or a thread). |
| let registrar_sym = unsafe { registrar_sym.into_raw() }; |
| mem::forget(lib); |
| |
| Ok(*registrar_sym) |
| } |