1 //! Reading and writing of the rustc metadata for rlibs and dylibs
7 use rustc_codegen_ssa::METADATA_FILENAME;
8 use rustc_data_structures::owning_ref::{OwningRef, StableAddress};
9 use rustc_data_structures::rustc_erase_owner;
10 use rustc_data_structures::sync::MetadataRef;
11 use rustc_middle::middle::cstore::{EncodedMetadata, MetadataLoader};
12 use rustc_middle::ty::TyCtxt;
13 use rustc_session::config;
14 use rustc_target::spec::Target;
16 use crate::backend::WriteMetadata;
18 pub(crate) struct CraneliftMetadataLoader;
20 struct StableMmap(memmap2::Mmap);
22 impl Deref for StableMmap {
25 fn deref(&self) -> &[u8] {
30 unsafe impl StableAddress for StableMmap {}
32 fn load_metadata_with(
34 f: impl for<'a> FnOnce(&'a [u8]) -> Result<&'a [u8], String>,
35 ) -> Result<MetadataRef, String> {
36 let file = File::open(path).map_err(|e| format!("{:?}", e))?;
37 let data = unsafe { memmap2::MmapOptions::new().map_copy_read_only(&file) }
38 .map_err(|e| format!("{:?}", e))?;
39 let metadata = OwningRef::new(StableMmap(data)).try_map(f)?;
40 return Ok(rustc_erase_owner!(metadata.map_owner_box()));
43 impl MetadataLoader for CraneliftMetadataLoader {
44 fn get_rlib_metadata(&self, _target: &Target, path: &Path) -> Result<MetadataRef, String> {
45 load_metadata_with(path, |data| {
46 let archive = object::read::archive::ArchiveFile::parse(&*data)
47 .map_err(|e| format!("{:?}", e))?;
49 for entry_result in archive.members() {
50 let entry = entry_result.map_err(|e| format!("{:?}", e))?;
51 if entry.name() == METADATA_FILENAME.as_bytes() {
52 return Ok(entry.data());
56 Err("couldn't find metadata entry".to_string())
60 fn get_dylib_metadata(&self, _target: &Target, path: &Path) -> Result<MetadataRef, String> {
61 use object::{Object, ObjectSection};
63 load_metadata_with(path, |data| {
64 let file = object::File::parse(&data).map_err(|e| format!("parse: {:?}", e))?;
65 file.section_by_name(".rustc")
66 .ok_or("no .rustc section")?
68 .map_err(|e| format!("failed to read .rustc section: {:?}", e))
73 // Adapted from https://github.com/rust-lang/rust/blob/da573206f87b5510de4b0ee1a9c044127e409bd3/src/librustc_codegen_llvm/base.rs#L47-L112
74 pub(crate) fn write_metadata<P: WriteMetadata>(
77 ) -> EncodedMetadata {
78 use snap::write::FrameEncoder;
81 #[derive(PartialEq, Eq, PartialOrd, Ord)]
93 config::CrateType::Executable
94 | config::CrateType::Staticlib
95 | config::CrateType::Cdylib => MetadataKind::None,
97 config::CrateType::Rlib => MetadataKind::Uncompressed,
99 config::CrateType::Dylib | config::CrateType::ProcMacro => MetadataKind::Compressed,
102 .unwrap_or(MetadataKind::None);
104 if kind == MetadataKind::None {
105 return EncodedMetadata::new();
108 let metadata = tcx.encode_metadata();
109 if kind == MetadataKind::Uncompressed {
113 assert!(kind == MetadataKind::Compressed);
114 let mut compressed = tcx.metadata_encoding_version();
115 FrameEncoder::new(&mut compressed).write_all(&metadata.raw_data).unwrap();
117 product.add_rustc_section(
118 rustc_middle::middle::exported_symbols::metadata_symbol_name(tcx),
120 tcx.sess.target.is_like_osx,