113 lines
4.4 KiB
Rust
113 lines
4.4 KiB
Rust
use crate::llvm;
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use crate::llvm::archive_ro::ArchiveRO;
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use crate::llvm::{mk_section_iter, False, ObjectFile};
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use rustc::middle::cstore::MetadataLoader;
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use rustc_target::spec::Target;
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use log::debug;
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use rustc_codegen_ssa::METADATA_FILENAME;
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use rustc_data_structures::owning_ref::OwningRef;
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use rustc_data_structures::rustc_erase_owner;
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use rustc_fs_util::path_to_c_string;
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use std::path::Path;
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use std::slice;
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pub use rustc_data_structures::sync::MetadataRef;
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pub struct LlvmMetadataLoader;
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impl MetadataLoader for LlvmMetadataLoader {
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fn get_rlib_metadata(&self, _: &Target, filename: &Path) -> Result<MetadataRef, String> {
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// Use ArchiveRO for speed here, it's backed by LLVM and uses mmap
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// internally to read the file. We also avoid even using a memcpy by
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// just keeping the archive along while the metadata is in use.
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let archive =
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ArchiveRO::open(filename).map(|ar| OwningRef::new(Box::new(ar))).map_err(|e| {
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debug!("llvm didn't like `{}`: {}", filename.display(), e);
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format!("failed to read rlib metadata in '{}': {}", filename.display(), e)
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})?;
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let buf: OwningRef<_, [u8]> = archive.try_map(|ar| {
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ar.iter()
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.filter_map(|s| s.ok())
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.find(|sect| sect.name() == Some(METADATA_FILENAME))
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.map(|s| s.data())
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.ok_or_else(|| {
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debug!("didn't find '{}' in the archive", METADATA_FILENAME);
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format!("failed to read rlib metadata: '{}'", filename.display())
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})
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})?;
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Ok(rustc_erase_owner!(buf))
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}
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fn get_dylib_metadata(&self, target: &Target, filename: &Path) -> Result<MetadataRef, String> {
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unsafe {
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let buf = path_to_c_string(filename);
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let mb = llvm::LLVMRustCreateMemoryBufferWithContentsOfFile(buf.as_ptr())
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.ok_or_else(|| format!("error reading library: '{}'", filename.display()))?;
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let of =
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ObjectFile::new(mb).map(|of| OwningRef::new(Box::new(of))).ok_or_else(|| {
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format!("provided path not an object file: '{}'", filename.display())
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})?;
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let buf = of.try_map(|of| search_meta_section(of, target, filename))?;
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Ok(rustc_erase_owner!(buf))
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}
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}
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}
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fn search_meta_section<'a>(
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of: &'a ObjectFile,
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target: &Target,
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filename: &Path,
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) -> Result<&'a [u8], String> {
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unsafe {
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let si = mk_section_iter(of.llof);
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while llvm::LLVMIsSectionIteratorAtEnd(of.llof, si.llsi) == False {
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let mut name_buf = None;
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let name_len = llvm::LLVMRustGetSectionName(si.llsi, &mut name_buf);
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let name = name_buf.map_or(
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String::new(), // We got a NULL ptr, ignore `name_len`.
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|buf| {
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String::from_utf8(
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slice::from_raw_parts(buf.as_ptr() as *const u8, name_len as usize)
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.to_vec(),
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)
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.unwrap()
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},
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);
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debug!("get_metadata_section: name {}", name);
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if read_metadata_section_name(target) == name {
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let cbuf = llvm::LLVMGetSectionContents(si.llsi);
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let csz = llvm::LLVMGetSectionSize(si.llsi) as usize;
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// The buffer is valid while the object file is around
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let buf: &'a [u8] = slice::from_raw_parts(cbuf as *const u8, csz);
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return Ok(buf);
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}
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llvm::LLVMMoveToNextSection(si.llsi);
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}
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}
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Err(format!("metadata not found: '{}'", filename.display()))
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}
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pub fn metadata_section_name(target: &Target) -> &'static str {
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// Historical note:
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//
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// When using link.exe it was seen that the section name `.note.rustc`
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// was getting shortened to `.note.ru`, and according to the PE and COFF
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// specification:
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//
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// > Executable images do not use a string table and do not support
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// > section names longer than 8 characters
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//
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// https://docs.microsoft.com/en-us/windows/win32/debug/pe-format
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//
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// As a result, we choose a slightly shorter name! As to why
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// `.note.rustc` works on MinGW, that's another good question...
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if target.options.is_like_osx { "__DATA,.rustc" } else { ".rustc" }
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}
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fn read_metadata_section_name(_target: &Target) -> &'static str {
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".rustc"
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}
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