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//! Handles dynamic library loading for proc macro
use std::{
fmt,
fs::File,
io,
path::{Path, PathBuf},
};
use libloading::Library;
use memmap2::Mmap;
use object::Object;
use paths::AbsPath;
use proc_macro_api::{read_dylib_info, ProcMacroKind};
use super::abis::Abi;
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()) }
}
#[derive(Debug)]
pub enum LoadProcMacroDylibError {
Io(io::Error),
LibLoading(libloading::Error),
UnsupportedABI,
}
impl fmt::Display for LoadProcMacroDylibError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Io(e) => e.fmt(f),
Self::UnsupportedABI => write!(f, "unsupported ABI version"),
Self::LibLoading(e) => e.fmt(f),
}
}
}
impl From<io::Error> for LoadProcMacroDylibError {
fn from(e: io::Error) -> Self {
LoadProcMacroDylibError::Io(e)
}
}
impl From<libloading::Error> for LoadProcMacroDylibError {
fn from(e: libloading::Error) -> Self {
LoadProcMacroDylibError::LibLoading(e)
}
}
struct ProcMacroLibraryLibloading {
// Hold on to the library so it doesn't unload
_lib: Library,
abi: Abi,
}
impl ProcMacroLibraryLibloading {
fn open(file: &Path) -> Result<Self, LoadProcMacroDylibError> {
let symbol_name = find_registrar_symbol(file)?.ok_or_else(|| {
invalid_data_err(format!("Cannot find registrar symbol in file {}", file.display()))
})?;
let abs_file: &AbsPath = file.try_into().map_err(|_| {
invalid_data_err(format!("expected an absolute path, got {}", file.display()))
})?;
let version_info = read_dylib_info(abs_file)?;
let lib = load_library(file).map_err(invalid_data_err)?;
let abi = Abi::from_lib(&lib, symbol_name, version_info)?;
Ok(ProcMacroLibraryLibloading { _lib: lib, abi })
}
}
pub struct Expander {
inner: ProcMacroLibraryLibloading,
}
impl Expander {
pub fn new(lib: &Path) -> Result<Expander, LoadProcMacroDylibError> {
// 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.as_ref())?;
Ok(Expander { inner: library })
}
pub fn expand(
&self,
macro_name: &str,
macro_body: &tt::Subtree,
attributes: Option<&tt::Subtree>,
) -> Result<tt::Subtree, String> {
let result = self.inner.abi.expand(macro_name, macro_body, attributes);
result.map_err(|e| e.as_str().unwrap_or_else(|| "<unknown error>".to_string()))
}
pub fn list_macros(&self) -> Vec<(String, ProcMacroKind)> {
self.inner.abi.list_macros()
}
}
/// 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::collections::hash_map::RandomState;
use std::ffi::OsString;
use std::hash::{BuildHasher, Hasher};
if std::env::var("RA_DONT_COPY_PROC_MACRO_DLL").is_ok() {
return Ok(path.to_path_buf());
}
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 unique number by abusing `HashMap`'s hasher.
// Maybe this will also "inspire" a libs team member to finally put `rand` in libstd.
let t = RandomState::new().build_hasher().finish();
let mut unique_name = OsString::from(t.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())
}
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