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Auto merge of #97485 - bjorn3:new_archive_writer, r=wesleywiser
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Rewrite LLVM's archive writer in Rust

This allows it to be used by other codegen backends.

Fixes https://github.com/bjorn3/rustc_codegen_cranelift/issues/1155
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@bors
bors committed Dec 3, 2022
2 parents a085a2a + 5399526 commit f1dc349
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6 changes: 0 additions & 6 deletions Cargo.lock
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1 change: 0 additions & 1 deletion Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@ target-lexicon = "0.12.0"
gimli = { version = "0.26.0", default-features = false, features = ["write"]}
object = { version = "0.29.0", default-features = false, features = ["std", "read_core", "write", "archive", "coff", "elf", "macho", "pe"] }

ar = { git = "https://github.com/bjorn3/rust-ar.git", branch = "do_not_remove_cg_clif_ranlib" }
indexmap = "1.9.1"
libloading = { version = "0.7.3", optional = true }
once_cell = "1.10.0"
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224 changes: 5 additions & 219 deletions src/archive.rs
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Original file line number Diff line number Diff line change
@@ -1,35 +1,15 @@
//! Creation of ar archives like for the lib and staticlib crate type

use std::collections::BTreeMap;
use std::fs::File;
use std::io::{self, Read, Seek};
use std::path::{Path, PathBuf};

use rustc_codegen_ssa::back::archive::{ArchiveBuilder, ArchiveBuilderBuilder};
use rustc_codegen_ssa::back::archive::{
get_native_object_symbols, ArArchiveBuilder, ArchiveBuilder, ArchiveBuilderBuilder,
};
use rustc_session::Session;

use object::read::archive::ArchiveFile;
use object::{Object, ObjectSymbol, ReadCache};

#[derive(Debug)]
enum ArchiveEntry {
FromArchive { archive_index: usize, file_range: (u64, u64) },
File(PathBuf),
}

pub(crate) struct ArArchiveBuilderBuilder;

impl ArchiveBuilderBuilder for ArArchiveBuilderBuilder {
fn new_archive_builder<'a>(&self, sess: &'a Session) -> Box<dyn ArchiveBuilder<'a> + 'a> {
Box::new(ArArchiveBuilder {
sess,
use_gnu_style_archive: sess.target.archive_format == "gnu",
// FIXME fix builtin ranlib on macOS
no_builtin_ranlib: sess.target.is_like_osx,

src_archives: vec![],
entries: vec![],
})
Box::new(ArArchiveBuilder::new(sess, get_native_object_symbols))
}

fn create_dll_import_lib(
Expand All @@ -40,200 +20,6 @@ impl ArchiveBuilderBuilder for ArArchiveBuilderBuilder {
_tmpdir: &Path,
_is_direct_dependency: bool,
) -> PathBuf {
bug!("creating dll imports is not supported");
}
}

pub(crate) struct ArArchiveBuilder<'a> {
sess: &'a Session,
use_gnu_style_archive: bool,
no_builtin_ranlib: bool,

src_archives: Vec<File>,
// Don't use `HashMap` here, as the order is important. `rust.metadata.bin` must always be at
// the end of an archive for linkers to not get confused.
entries: Vec<(Vec<u8>, ArchiveEntry)>,
}

impl<'a> ArchiveBuilder<'a> for ArArchiveBuilder<'a> {
fn add_file(&mut self, file: &Path) {
self.entries.push((
file.file_name().unwrap().to_str().unwrap().to_string().into_bytes(),
ArchiveEntry::File(file.to_owned()),
));
}

fn add_archive(
&mut self,
archive_path: &Path,
mut skip: Box<dyn FnMut(&str) -> bool + 'static>,
) -> std::io::Result<()> {
let read_cache = ReadCache::new(std::fs::File::open(&archive_path)?);
let archive = ArchiveFile::parse(&read_cache).unwrap();
let archive_index = self.src_archives.len();

for entry in archive.members() {
let entry = entry.map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))?;
let file_name = String::from_utf8(entry.name().to_vec())
.map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))?;
if !skip(&file_name) {
self.entries.push((
file_name.into_bytes(),
ArchiveEntry::FromArchive { archive_index, file_range: entry.file_range() },
));
}
}

self.src_archives.push(read_cache.into_inner());
Ok(())
}

fn build(mut self: Box<Self>, output: &Path) -> bool {
enum BuilderKind {
Bsd(ar::Builder<File>),
Gnu(ar::GnuBuilder<File>),
}

let sess = self.sess;

let mut symbol_table = BTreeMap::new();

let mut entries = Vec::new();

for (mut entry_name, entry) in self.entries {
// FIXME only read the symbol table of the object files to avoid having to keep all
// object files in memory at once, or read them twice.
let data = match entry {
ArchiveEntry::FromArchive { archive_index, file_range } => {
// FIXME read symbols from symtab
let src_read_cache = &mut self.src_archives[archive_index];

src_read_cache.seek(io::SeekFrom::Start(file_range.0)).unwrap();
let mut data = std::vec::from_elem(0, usize::try_from(file_range.1).unwrap());
src_read_cache.read_exact(&mut data).unwrap();

data
}
ArchiveEntry::File(file) => std::fs::read(file).unwrap_or_else(|err| {
sess.fatal(&format!(
"error while reading object file during archive building: {}",
err
));
}),
};

if !self.no_builtin_ranlib {
if symbol_table.contains_key(&entry_name) {
// The ar crate can't handle creating a symbol table in case of multiple archive
// members with the same name. Work around this by prepending a number until we
// get a unique name.
for i in 1.. {
let new_name = format!("{}_", i)
.into_bytes()
.into_iter()
.chain(entry_name.iter().copied())
.collect::<Vec<_>>();
if !symbol_table.contains_key(&new_name) {
entry_name = new_name;
break;
}
}
}

match object::File::parse(&*data) {
Ok(object) => {
symbol_table.insert(
entry_name.to_vec(),
object
.symbols()
.filter_map(|symbol| {
if symbol.is_undefined() || symbol.is_local() {
None
} else {
symbol.name().map(|name| name.as_bytes().to_vec()).ok()
}
})
.collect::<Vec<_>>(),
);
}
Err(err) => {
let err = err.to_string();
if err == "Unknown file magic" {
// Not an object file; skip it.
} else if object::read::archive::ArchiveFile::parse(&*data).is_ok() {
// Nested archive file; skip it.
} else {
sess.fatal(&format!(
"error parsing `{}` during archive creation: {}",
String::from_utf8_lossy(&entry_name),
err
));
}
}
}
}

entries.push((entry_name, data));
}

let mut builder = if self.use_gnu_style_archive {
BuilderKind::Gnu(
ar::GnuBuilder::new(
File::create(output).unwrap_or_else(|err| {
sess.fatal(&format!(
"error opening destination during archive building: {}",
err
));
}),
entries.iter().map(|(name, _)| name.clone()).collect(),
ar::GnuSymbolTableFormat::Size32,
symbol_table,
)
.unwrap(),
)
} else {
BuilderKind::Bsd(
ar::Builder::new(
File::create(output).unwrap_or_else(|err| {
sess.fatal(&format!(
"error opening destination during archive building: {}",
err
));
}),
symbol_table,
)
.unwrap(),
)
};

let any_members = !entries.is_empty();

// Add all files
for (entry_name, data) in entries.into_iter() {
let header = ar::Header::new(entry_name, data.len() as u64);
match builder {
BuilderKind::Bsd(ref mut builder) => builder.append(&header, &mut &*data).unwrap(),
BuilderKind::Gnu(ref mut builder) => builder.append(&header, &mut &*data).unwrap(),
}
}

// Finalize archive
std::mem::drop(builder);

if self.no_builtin_ranlib {
let ranlib = crate::toolchain::get_toolchain_binary(self.sess, "ranlib");

// Run ranlib to be able to link the archive
let status = std::process::Command::new(ranlib)
.arg(output)
.status()
.expect("Couldn't run ranlib");

if !status.success() {
self.sess.fatal(&format!("Ranlib exited with code {:?}", status.code()));
}
}

any_members
unimplemented!("creating dll imports is not yet supported");
}
}

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