1 //! Reading and writing of the rustc metadata for rlibs and dylibs
3 use std::convert::TryFrom;
7 use rustc_codegen_ssa::METADATA_FILENAME;
8 use rustc_data_structures::owning_ref::OwningRef;
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 impl MetadataLoader for CraneliftMetadataLoader {
21 fn get_rlib_metadata(&self, _target: &Target, path: &Path) -> Result<MetadataRef, String> {
22 let mut archive = ar::Archive::new(File::open(path).map_err(|e| format!("{:?}", e))?);
23 // Iterate over all entries in the archive:
24 while let Some(entry_result) = archive.next_entry() {
25 let mut entry = entry_result.map_err(|e| format!("{:?}", e))?;
26 if entry.header().identifier() == METADATA_FILENAME.as_bytes() {
27 let mut buf = Vec::with_capacity(
28 usize::try_from(entry.header().size())
29 .expect("Rlib metadata file too big to load into memory."),
31 ::std::io::copy(&mut entry, &mut buf).map_err(|e| format!("{:?}", e))?;
32 let buf: OwningRef<Vec<u8>, [u8]> = OwningRef::new(buf);
33 return Ok(rustc_erase_owner!(buf.map_owner_box()));
37 Err("couldn't find metadata entry".to_string())
40 fn get_dylib_metadata(&self, _target: &Target, path: &Path) -> Result<MetadataRef, String> {
41 use object::{Object, ObjectSection};
42 let file = std::fs::read(path).map_err(|e| format!("read:{:?}", e))?;
43 let file = object::File::parse(&file).map_err(|e| format!("parse: {:?}", e))?;
45 .section_by_name(".rustc")
46 .ok_or("no .rustc section")?
48 .map_err(|e| format!("failed to read .rustc section: {:?}", e))?
50 let buf: OwningRef<Vec<u8>, [u8]> = OwningRef::new(buf);
51 Ok(rustc_erase_owner!(buf.map_owner_box()))
55 // Adapted from https://github.com/rust-lang/rust/blob/da573206f87b5510de4b0ee1a9c044127e409bd3/src/librustc_codegen_llvm/base.rs#L47-L112
56 pub(crate) fn write_metadata<P: WriteMetadata>(
59 ) -> EncodedMetadata {
60 use snap::write::FrameEncoder;
63 #[derive(PartialEq, Eq, PartialOrd, Ord)]
75 config::CrateType::Executable
76 | config::CrateType::Staticlib
77 | config::CrateType::Cdylib => MetadataKind::None,
79 config::CrateType::Rlib => MetadataKind::Uncompressed,
81 config::CrateType::Dylib | config::CrateType::ProcMacro => MetadataKind::Compressed,
84 .unwrap_or(MetadataKind::None);
86 if kind == MetadataKind::None {
87 return EncodedMetadata::new();
90 let metadata = tcx.encode_metadata();
91 if kind == MetadataKind::Uncompressed {
95 assert!(kind == MetadataKind::Compressed);
96 let mut compressed = tcx.metadata_encoding_version();
97 FrameEncoder::new(&mut compressed)
98 .write_all(&metadata.raw_data)
101 product.add_rustc_section(
102 rustc_middle::middle::exported_symbols::metadata_symbol_name(tcx),
104 tcx.sess.target.options.is_like_osx,