src/metadata.rs

   1 use std::fs::File;
   2 use std::path::Path;
   3
   4 use rustc::middle::cstore::{EncodedMetadata, MetadataLoader};
   5 use rustc::session::config;
   6 use rustc::ty::TyCtxt;
   7 use rustc_codegen_ssa::METADATA_FILENAME;
   8 use rustc_data_structures::owning_ref::{self, OwningRef};
   9 use rustc_data_structures::rustc_erase_owner;
  10 use rustc_target::spec::Target;
  11
  12 use crate::backend::WriteMetadata;
  13
  14 pub struct CraneliftMetadataLoader;
  15
  16 impl MetadataLoader for CraneliftMetadataLoader {
  17     fn get_rlib_metadata(
  18         &self,
  19         _target: &Target,
  20         path: &Path,
  21     ) -> Result<owning_ref::ErasedBoxRef<[u8]>, 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::new();
  28                 ::std::io::copy(&mut entry, &mut buf).map_err(|e| format!("{:?}", e))?;
  29                 let buf: OwningRef<Vec<u8>, [u8]> = OwningRef::new(buf).into();
  30                 return Ok(rustc_erase_owner!(buf.map_owner_box()));
  31             }
  32         }
  33
  34         Err("couldn't find metadata entry".to_string())
  35         //self.get_dylib_metadata(target, path)
  36     }
  37
  38     fn get_dylib_metadata(
  39         &self,
  40         _target: &Target,
  41         path: &Path,
  42     ) -> Result<owning_ref::ErasedBoxRef<[u8]>, String> {
  43         use object::Object;
  44         let file = std::fs::read(path).map_err(|e| format!("read:{:?}", e))?;
  45         let file = object::File::parse(&file).map_err(|e| format!("parse: {:?}", e))?;
  46         let buf = file
  47             .section_data_by_name(".rustc")
  48             .ok_or("no .rustc section")?
  49             .into_owned();
  50         let buf: OwningRef<Vec<u8>, [u8]> = OwningRef::new(buf).into();
  51         Ok(rustc_erase_owner!(buf.map_owner_box()))
  52     }
  53 }
  54
  55 // Adapted from https://github.com/rust-lang/rust/blob/da573206f87b5510de4b0ee1a9c044127e409bd3/src/librustc_codegen_llvm/base.rs#L47-L112
  56 pub fn write_metadata<P: WriteMetadata>(tcx: TyCtxt<'_>, product: &mut P) -> EncodedMetadata {
  57     use flate2::write::DeflateEncoder;
  58     use flate2::Compression;
  59     use std::io::Write;
  60
  61     #[derive(PartialEq, Eq, PartialOrd, Ord)]
  62     enum MetadataKind {
  63         None,
  64         Uncompressed,
  65         Compressed,
  66     }
  67
  68     let kind = tcx
  69         .sess
  70         .crate_types
  71         .borrow()
  72         .iter()
  73         .map(|ty| match *ty {
  74             config::CrateType::Executable
  75             | config::CrateType::Staticlib
  76             | config::CrateType::Cdylib => MetadataKind::None,
  77
  78             config::CrateType::Rlib => MetadataKind::Uncompressed,
  79
  80             config::CrateType::Dylib | config::CrateType::ProcMacro => MetadataKind::Compressed,
  81         })
  82         .max()
  83         .unwrap_or(MetadataKind::None);
  84
  85     if kind == MetadataKind::None {
  86         return EncodedMetadata::new();
  87     }
  88
  89     let metadata = tcx.encode_metadata();
  90     if kind == MetadataKind::Uncompressed {
  91         return metadata;
  92     }
  93
  94     assert!(kind == MetadataKind::Compressed);
  95     let mut compressed = tcx.metadata_encoding_version();
  96     DeflateEncoder::new(&mut compressed, Compression::fast())
  97         .write_all(&metadata.raw_data)
  98         .unwrap();
  99
 100     product.add_rustc_section(
 101         rustc::middle::exported_symbols::metadata_symbol_name(tcx),
 102         compressed,
 103         tcx.sess.target.target.options.is_like_osx,
 104     );
 105
 106     metadata
 107 }