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|
//! Handles dynamic library loading for proc macro
use std::{
fs::File,
io,
path::{Path, PathBuf},
};
use libloading::Library;
use memmap2::Mmap;
use object::Object;
use proc_macro_api::ProcMacroKind;
use crate::{proc_macro::bridge, rustc_server::TokenStream};
const NEW_REGISTRAR_SYMBOL: &str = "_rustc_proc_macro_decls_";
fn invalid_data_err(e: impl Into<Box<dyn std::error::Error + Send + Sync>>) -> io::Error {
io::Error::new(io::ErrorKind::InvalidData, e)
}
fn is_derive_registrar_symbol(symbol: &str) -> bool {
symbol.contains(NEW_REGISTRAR_SYMBOL)
}
fn find_registrar_symbol(file: &Path) -> io::Result<Option<String>> {
let file = File::open(file)?;
let buffer = unsafe { Mmap::map(&file)? };
Ok(object::File::parse(&*buffer)
.map_err(invalid_data_err)?
.exports()
.map_err(invalid_data_err)?
.into_iter()
.map(|export| export.name())
.filter_map(|sym| String::from_utf8(sym.into()).ok())
.find(|sym| is_derive_registrar_symbol(sym))
.map(|sym| {
// From MacOS docs:
// https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/dlsym.3.html
// Unlike other dyld API's, the symbol name passed to dlsym() must NOT be
// prepended with an underscore.
if cfg!(target_os = "macos") && sym.starts_with('_') {
sym[1..].to_owned()
} else {
sym
}
}))
}
/// 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> {
unsafe { 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;
unsafe { UnixLibrary::open(Some(file), RTLD_NOW | RTLD_DEEPBIND).map(|lib| lib.into()) }
}
struct ProcMacroLibraryLibloading {
// Hold the dylib to prevent it from unloading
_lib: Library,
exported_macros: Vec<bridge::client::ProcMacro>,
}
impl ProcMacroLibraryLibloading {
fn open(file: &Path) -> io::Result<Self> {
let symbol_name = find_registrar_symbol(file)?.ok_or_else(|| {
invalid_data_err(format!("Cannot find registrar symbol in file {}", file.display()))
})?;
let lib = load_library(file).map_err(invalid_data_err)?;
let exported_macros = {
let macros: libloading::Symbol<&&[bridge::client::ProcMacro]> =
unsafe { lib.get(symbol_name.as_bytes()) }.map_err(invalid_data_err)?;
macros.to_vec()
};
Ok(ProcMacroLibraryLibloading { _lib: lib, exported_macros })
}
}
pub struct Expander {
inner: ProcMacroLibraryLibloading,
}
impl Expander {
pub fn new(lib: &Path) -> io::Result<Expander> {
// Some libraries for dynamic loading require canonicalized path even when it is
// already absolute
let lib = lib.canonicalize()?;
let lib = ensure_file_with_lock_free_access(&lib)?;
let library = ProcMacroLibraryLibloading::open(&lib)?;
Ok(Expander { inner: library })
}
pub fn expand(
&self,
macro_name: &str,
macro_body: &tt::Subtree,
attributes: Option<&tt::Subtree>,
) -> Result<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 proc_macro in &self.inner.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,
false,
);
return res.map(|it| it.into_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,
false,
);
return res.map(|it| it.into_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,
false,
);
return res.map(|it| it.into_subtree());
}
_ => continue,
}
}
Err(bridge::PanicMessage::String("Nothing to expand".to_string()))
}
pub fn list_macros(&self) -> Vec<(String, ProcMacroKind)> {
self.inner
.exported_macros
.iter()
.map(|proc_macro| 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)
}
})
.collect()
}
}
/// Copy the dylib to temp directory to prevent locking in Windows
#[cfg(windows)]
fn ensure_file_with_lock_free_access(path: &Path) -> io::Result<PathBuf> {
use std::{ffi::OsString, time::SystemTime};
let mut to = std::env::temp_dir();
let file_name = path.file_name().ok_or_else(|| {
io::Error::new(
io::ErrorKind::InvalidInput,
format!("File path is invalid: {}", path.display()),
)
})?;
// generate a time deps unique number
let t = SystemTime::now().duration_since(std::time::UNIX_EPOCH).expect("Time went backwards");
let mut unique_name = OsString::from(t.as_millis().to_string());
unique_name.push(file_name);
to.push(unique_name);
std::fs::copy(path, &to).unwrap();
Ok(to)
}
#[cfg(unix)]
fn ensure_file_with_lock_free_access(path: &Path) -> io::Result<PathBuf> {
Ok(path.to_path_buf())
}
|
