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//! Handles dynamic library loading for proc macro
use crate::{proc_macro::bridge, rustc_server::TokenStream};
use std::fs::File;
use std::io::Read;
use std::path::Path;
use goblin::{mach::Mach, Object};
use libloading::Library;
use ra_proc_macro::ProcMacroKind;
static NEW_REGISTRAR_SYMBOL: &str = "__rustc_proc_macro_decls_";
static _OLD_REGISTRAR_SYMBOL: &str = "__rustc_derive_registrar_";
fn read_bytes(file: &Path) -> Option<Vec<u8>> {
let mut fd = File::open(file).ok()?;
let mut buffer = Vec::new();
fd.read_to_end(&mut buffer).ok()?;
Some(buffer)
}
fn get_symbols_from_lib(file: &Path) -> Option<Vec<String>> {
let buffer = read_bytes(file)?;
let object = Object::parse(&buffer).ok()?;
return match object {
Object::Elf(elf) => {
let symbols = elf.dynstrtab.to_vec().ok()?;
let names = symbols.iter().map(|s| s.to_string()).collect();
Some(names)
}
Object::PE(pe) => {
let symbol_names =
pe.exports.iter().flat_map(|s| s.name).map(|n| n.to_string()).collect();
Some(symbol_names)
}
Object::Mach(mach) => match mach {
Mach::Binary(binary) => {
let exports = binary.exports().ok()?;
let names = exports.iter().map(|s| s.name.clone()).collect();
Some(names)
}
Mach::Fat(_) => None,
},
Object::Archive(_) | Object::Unknown(_) => None,
};
}
fn is_derive_registrar_symbol(symbol: &str) -> bool {
symbol.contains(NEW_REGISTRAR_SYMBOL)
}
fn find_registrar_symbol(file: &Path) -> Option<String> {
let symbols = get_symbols_from_lib(file)?;
symbols.iter().find(|s| is_derive_registrar_symbol(s)).map(|s| s.to_string())
}
/// Loads dynamic library in platform dependent manner.
///
/// For unix, you have to use RTLD_DEEPBIND flag to escape problems described
/// [here](https://github.com/fedochet/rust-proc-macro-panic-inside-panic-expample)
/// and [here](https://github.com/rust-lang/rust/issues/60593).
///
/// Usage of RTLD_DEEPBIND
/// [here](https://github.com/fedochet/rust-proc-macro-panic-inside-panic-expample/issues/1)
///
/// It seems that on Windows that behaviour is default, so we do nothing in that case.
#[cfg(windows)]
fn load_library(file: &Path) -> Result<Library, libloading::Error> {
Library::new(file)
}
#[cfg(unix)]
fn load_library(file: &Path) -> Result<Library, libloading::Error> {
use libloading::os::unix::Library as UnixLibrary;
use std::os::raw::c_int;
const RTLD_NOW: c_int = 0x00002;
const RTLD_DEEPBIND: c_int = 0x00008;
UnixLibrary::open(Some(file), RTLD_NOW | RTLD_DEEPBIND).map(|lib| lib.into())
}
struct ProcMacroLibraryLibloading {
// Hold the dylib to prevent it for unloadeding
_lib: Library,
exported_macros: Vec<bridge::client::ProcMacro>,
}
impl ProcMacroLibraryLibloading {
fn open(file: &Path) -> Result<Self, String> {
let symbol_name = find_registrar_symbol(file)
.ok_or(format!("Cannot find registrar symbol in file {:?}", file))?;
let lib = load_library(file).map_err(|e| e.to_string())?;
let exported_macros = {
let macros: libloading::Symbol<&&[bridge::client::ProcMacro]> =
unsafe { lib.get(symbol_name.as_bytes()) }.map_err(|e| e.to_string())?;
macros.to_vec()
};
Ok(ProcMacroLibraryLibloading { _lib: lib, exported_macros })
}
}
type ProcMacroLibraryImpl = ProcMacroLibraryLibloading;
pub struct Expander {
libs: Vec<ProcMacroLibraryImpl>,
}
impl Expander {
pub fn new<P: AsRef<Path>>(lib: &P) -> Result<Expander, String> {
let mut libs = vec![];
/* Some libraries for dynamic loading require canonicalized path (even when it is
already absolute
*/
let lib =
lib.as_ref().canonicalize().expect(&format!("Cannot canonicalize {:?}", lib.as_ref()));
let library = ProcMacroLibraryImpl::open(&lib)?;
libs.push(library);
Ok(Expander { libs })
}
pub fn expand(
&self,
macro_name: &str,
macro_body: &ra_tt::Subtree,
attributes: Option<&ra_tt::Subtree>,
) -> Result<ra_tt::Subtree, bridge::PanicMessage> {
let parsed_body = TokenStream::with_subtree(macro_body.clone());
let parsed_attributes = attributes
.map_or(crate::rustc_server::TokenStream::new(), |attr| {
TokenStream::with_subtree(attr.clone())
});
for lib in &self.libs {
for proc_macro in &lib.exported_macros {
match proc_macro {
bridge::client::ProcMacro::CustomDerive { trait_name, client, .. }
if *trait_name == macro_name =>
{
let res = client.run(
&crate::proc_macro::bridge::server::SameThread,
crate::rustc_server::Rustc::default(),
parsed_body,
);
return res.map(|it| it.subtree);
}
bridge::client::ProcMacro::Bang { name, client } if *name == macro_name => {
let res = client.run(
&crate::proc_macro::bridge::server::SameThread,
crate::rustc_server::Rustc::default(),
parsed_body,
);
return res.map(|it| it.subtree);
}
bridge::client::ProcMacro::Attr { name, client } if *name == macro_name => {
let res = client.run(
&crate::proc_macro::bridge::server::SameThread,
crate::rustc_server::Rustc::default(),
parsed_attributes,
parsed_body,
);
return res.map(|it| it.subtree);
}
_ => {
continue;
}
}
}
}
Err(bridge::PanicMessage::String("Nothing to expand".to_string()))
}
pub fn list_macros(&self) -> Result<Vec<(String, ProcMacroKind)>, bridge::PanicMessage> {
let mut result = vec![];
for lib in &self.libs {
for proc_macro in &lib.exported_macros {
let res = match proc_macro {
bridge::client::ProcMacro::CustomDerive { trait_name, .. } => {
(trait_name.to_string(), ProcMacroKind::CustomDerive)
}
bridge::client::ProcMacro::Bang { name, .. } => {
(name.to_string(), ProcMacroKind::FuncLike)
}
bridge::client::ProcMacro::Attr { name, .. } => {
(name.to_string(), ProcMacroKind::Attr)
}
};
result.push(res);
}
}
Ok(result)
}
}
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