// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use super::archive::{ArchiveBuilder, ArchiveConfig}; use super::linker::{Linker, GnuLinker, MsvcLinker}; use super::rpath::RPathConfig; use super::rpath; use super::msvc; use super::svh::Svh; use session::config; use session::config::NoDebugInfo; use session::config::{OutputFilenames, Input, OutputTypeBitcode, OutputTypeExe, OutputTypeObject}; use session::search_paths::PathKind; use session::Session; use metadata::common::LinkMeta; use metadata::filesearch::FileDoesntMatch; use metadata::loader::METADATA_FILENAME; use metadata::{encoder, cstore, filesearch, csearch, creader}; use middle::ty::{self, Ty}; use rustc::ast_map::{PathElem, PathElems, PathName}; use trans::{CrateContext, CrateTranslation, gensym_name}; use util::common::time; use util::sha2::{Digest, Sha256}; use util::fs::fix_windows_verbatim_for_gcc; use rustc_back::tempdir::TempDir; use std::env; use std::ffi::OsString; use std::fs::{self, PathExt}; use std::io::{self, Read, Write}; use std::mem; use std::path::{Path, PathBuf}; use std::process::Command; use std::str; use flate; use serialize::hex::ToHex; use syntax::ast; use syntax::attr::AttrMetaMethods; use syntax::codemap::Span; use syntax::parse::token; // RLIB LLVM-BYTECODE OBJECT LAYOUT // Version 1 // Bytes Data // 0..10 "RUST_OBJECT" encoded in ASCII // 11..14 format version as little-endian u32 // 15..22 size in bytes of deflate compressed LLVM bitcode as // little-endian u64 // 23.. compressed LLVM bitcode // This is the "magic number" expected at the beginning of a LLVM bytecode // object in an rlib. pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT"; // The version number this compiler will write to bytecode objects in rlibs pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1; // The offset in bytes the bytecode object format version number can be found at pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11; // The offset in bytes the size of the compressed bytecode can be found at in // format version 1 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize = RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4; // The offset in bytes the compressed LLVM bytecode can be found at in format // version 1 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize = RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8; /* * Name mangling and its relationship to metadata. This is complex. Read * carefully. * * The semantic model of Rust linkage is, broadly, that "there's no global * namespace" between crates. Our aim is to preserve the illusion of this * model despite the fact that it's not *quite* possible to implement on * modern linkers. We initially didn't use system linkers at all, but have * been convinced of their utility. * * There are a few issues to handle: * * - Linkers operate on a flat namespace, so we have to flatten names. * We do this using the C++ namespace-mangling technique. Foo::bar * symbols and such. * * - Symbols with the same name but different types need to get different * linkage-names. We do this by hashing a string-encoding of the type into * a fixed-size (currently 16-byte hex) cryptographic hash function (CHF: * we use SHA256) to "prevent collisions". This is not airtight but 16 hex * digits on uniform probability means you're going to need 2**32 same-name * symbols in the same process before you're even hitting birthday-paradox * collision probability. * * - Symbols in different crates but with same names "within" the crate need * to get different linkage-names. * * - The hash shown in the filename needs to be predictable and stable for * build tooling integration. It also needs to be using a hash function * which is easy to use from Python, make, etc. * * So here is what we do: * * - Consider the package id; every crate has one (specified with crate_id * attribute). If a package id isn't provided explicitly, we infer a * versionless one from the output name. The version will end up being 0.0 * in this case. CNAME and CVERS are taken from this package id. For * example, github.com/mozilla/CNAME#CVERS. * * - Define CMH as SHA256(crateid). * * - Define CMH8 as the first 8 characters of CMH. * * - Compile our crate to lib CNAME-CMH8-CVERS.so * * - Define STH(sym) as SHA256(CMH, type_str(sym)) * * - Suffix a mangled sym with ::STH@CVERS, so that it is unique in the * name, non-name metadata, and type sense, and versioned in the way * system linkers understand. */ pub fn find_crate_name(sess: Option<&Session>, attrs: &[ast::Attribute], input: &Input) -> String { let validate = |s: String, span: Option| { creader::validate_crate_name(sess, &s[..], span); s }; // Look in attributes 100% of the time to make sure the attribute is marked // as used. After doing this, however, we still prioritize a crate name from // the command line over one found in the #[crate_name] attribute. If we // find both we ensure that they're the same later on as well. let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name")) .and_then(|at| at.value_str().map(|s| (at, s))); if let Some(sess) = sess { if let Some(ref s) = sess.opts.crate_name { if let Some((attr, ref name)) = attr_crate_name { if *s != &name[..] { let msg = format!("--crate-name and #[crate_name] are \ required to match, but `{}` != `{}`", s, name); sess.span_err(attr.span, &msg[..]); } } return validate(s.clone(), None); } } if let Some((attr, s)) = attr_crate_name { return validate(s.to_string(), Some(attr.span)); } if let Input::File(ref path) = *input { if let Some(s) = path.file_stem().and_then(|s| s.to_str()) { if s.starts_with("-") { let msg = format!("crate names cannot start with a `-`, but \ `{}` has a leading hyphen", s); if let Some(sess) = sess { sess.err(&msg); } } else { return validate(s.replace("-", "_"), None); } } } "rust_out".to_string() } pub fn build_link_meta(sess: &Session, krate: &ast::Crate, name: String) -> LinkMeta { let r = LinkMeta { crate_name: name, crate_hash: Svh::calculate(&sess.opts.cg.metadata, krate), }; info!("{:?}", r); return r; } fn truncated_hash_result(symbol_hasher: &mut Sha256) -> String { let output = symbol_hasher.result_bytes(); // 64 bits should be enough to avoid collisions. output[.. 8].to_hex().to_string() } // This calculates STH for a symbol, as defined above fn symbol_hash<'tcx>(tcx: &ty::ctxt<'tcx>, symbol_hasher: &mut Sha256, t: Ty<'tcx>, link_meta: &LinkMeta) -> String { // NB: do *not* use abbrevs here as we want the symbol names // to be independent of one another in the crate. symbol_hasher.reset(); symbol_hasher.input_str(&link_meta.crate_name); symbol_hasher.input_str("-"); symbol_hasher.input_str(link_meta.crate_hash.as_str()); for meta in tcx.sess.crate_metadata.borrow().iter() { symbol_hasher.input_str(&meta[..]); } symbol_hasher.input_str("-"); symbol_hasher.input_str(&encoder::encoded_ty(tcx, t)); // Prefix with 'h' so that it never blends into adjacent digits let mut hash = String::from("h"); hash.push_str(&truncated_hash_result(symbol_hasher)); hash } fn get_symbol_hash<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) -> String { match ccx.type_hashcodes().borrow().get(&t) { Some(h) => return h.to_string(), None => {} } let mut symbol_hasher = ccx.symbol_hasher().borrow_mut(); let hash = symbol_hash(ccx.tcx(), &mut *symbol_hasher, t, ccx.link_meta()); ccx.type_hashcodes().borrow_mut().insert(t, hash.clone()); hash } // Name sanitation. LLVM will happily accept identifiers with weird names, but // gas doesn't! // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $ pub fn sanitize(s: &str) -> String { let mut result = String::new(); for c in s.chars() { match c { // Escape these with $ sequences '@' => result.push_str("$SP$"), '*' => result.push_str("$BP$"), '&' => result.push_str("$RF$"), '<' => result.push_str("$LT$"), '>' => result.push_str("$GT$"), '(' => result.push_str("$LP$"), ')' => result.push_str("$RP$"), ',' => result.push_str("$C$"), // '.' doesn't occur in types and functions, so reuse it // for ':' and '-' '-' | ':' => result.push('.'), // These are legal symbols 'a' ... 'z' | 'A' ... 'Z' | '0' ... '9' | '_' | '.' | '$' => result.push(c), _ => { result.push('$'); for c in c.escape_unicode().skip(1) { match c { '{' => {}, '}' => result.push('$'), c => result.push(c), } } } } } // Underscore-qualify anything that didn't start as an ident. if !result.is_empty() && result.as_bytes()[0] != '_' as u8 && ! (result.as_bytes()[0] as char).is_xid_start() { return format!("_{}", &result[..]); } return result; } pub fn mangle>(path: PI, hash: Option<&str>) -> String { // Follow C++ namespace-mangling style, see // http://en.wikipedia.org/wiki/Name_mangling for more info. // // It turns out that on OSX you can actually have arbitrary symbols in // function names (at least when given to LLVM), but this is not possible // when using unix's linker. Perhaps one day when we just use a linker from LLVM // we won't need to do this name mangling. The problem with name mangling is // that it seriously limits the available characters. For example we can't // have things like &T in symbol names when one would theoretically // want them for things like impls of traits on that type. // // To be able to work on all platforms and get *some* reasonable output, we // use C++ name-mangling. let mut n = String::from("_ZN"); // _Z == Begin name-sequence, N == nested fn push(n: &mut String, s: &str) { let sani = sanitize(s); n.push_str(&format!("{}{}", sani.len(), sani)); } // First, connect each component with pairs. for e in path { push(&mut n, &e.name().as_str()) } match hash { Some(s) => push(&mut n, s), None => {} } n.push('E'); // End name-sequence. n } pub fn exported_name(path: PathElems, hash: &str) -> String { mangle(path, Some(hash)) } pub fn mangle_exported_name<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, path: PathElems, t: Ty<'tcx>, id: ast::NodeId) -> String { let mut hash = get_symbol_hash(ccx, t); // Paths can be completely identical for different nodes, // e.g. `fn foo() { { fn a() {} } { fn a() {} } }`, so we // generate unique characters from the node id. For now // hopefully 3 characters is enough to avoid collisions. const EXTRA_CHARS: &'static str = "abcdefghijklmnopqrstuvwxyz\ ABCDEFGHIJKLMNOPQRSTUVWXYZ\ 0123456789"; let id = id as usize; let extra1 = id % EXTRA_CHARS.len(); let id = id / EXTRA_CHARS.len(); let extra2 = id % EXTRA_CHARS.len(); let id = id / EXTRA_CHARS.len(); let extra3 = id % EXTRA_CHARS.len(); hash.push(EXTRA_CHARS.as_bytes()[extra1] as char); hash.push(EXTRA_CHARS.as_bytes()[extra2] as char); hash.push(EXTRA_CHARS.as_bytes()[extra3] as char); exported_name(path, &hash[..]) } pub fn mangle_internal_name_by_type_and_seq<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>, name: &str) -> String { let path = [PathName(token::intern(&t.to_string())), gensym_name(name)]; let hash = get_symbol_hash(ccx, t); mangle(path.iter().cloned(), Some(&hash[..])) } pub fn mangle_internal_name_by_path_and_seq(path: PathElems, flav: &str) -> String { mangle(path.chain(Some(gensym_name(flav))), None) } pub fn get_linker(sess: &Session) -> (String, Command) { if let Some(ref linker) = sess.opts.cg.linker { (linker.clone(), Command::new(linker)) } else if sess.target.target.options.is_like_msvc { ("link.exe".to_string(), msvc::link_exe_cmd(sess)) } else { (sess.target.target.options.linker.clone(), Command::new(&sess.target.target.options.linker)) } } pub fn get_ar_prog(sess: &Session) -> String { sess.opts.cg.ar.clone().unwrap_or_else(|| { sess.target.target.options.ar.clone() }) } fn command_path(sess: &Session) -> OsString { // The compiler's sysroot often has some bundled tools, so add it to the // PATH for the child. let mut new_path = sess.host_filesearch(PathKind::All) .get_tools_search_paths(); if let Some(path) = env::var_os("PATH") { new_path.extend(env::split_paths(&path)); } env::join_paths(new_path).unwrap() } pub fn remove(sess: &Session, path: &Path) { match fs::remove_file(path) { Ok(..) => {} Err(e) => { sess.err(&format!("failed to remove {}: {}", path.display(), e)); } } } /// Perform the linkage portion of the compilation phase. This will generate all /// of the requested outputs for this compilation session. pub fn link_binary(sess: &Session, trans: &CrateTranslation, outputs: &OutputFilenames, crate_name: &str) -> Vec { let mut out_filenames = Vec::new(); for &crate_type in sess.crate_types.borrow().iter() { if invalid_output_for_target(sess, crate_type) { sess.bug(&format!("invalid output type `{:?}` for target os `{}`", crate_type, sess.opts.target_triple)); } let out_file = link_binary_output(sess, trans, crate_type, outputs, crate_name); out_filenames.push(out_file); } // Remove the temporary object file and metadata if we aren't saving temps if !sess.opts.cg.save_temps { for obj in object_filenames(sess, outputs) { remove(sess, &obj); } remove(sess, &outputs.with_extension("metadata.o")); } out_filenames } /// Returns default crate type for target /// /// Default crate type is used when crate type isn't provided neither /// through cmd line arguments nor through crate attributes /// /// It is CrateTypeExecutable for all platforms but iOS as there is no /// way to run iOS binaries anyway without jailbreaking and /// interaction with Rust code through static library is the only /// option for now pub fn default_output_for_target(sess: &Session) -> config::CrateType { if !sess.target.target.options.executables { config::CrateTypeStaticlib } else { config::CrateTypeExecutable } } /// Checks if target supports crate_type as output pub fn invalid_output_for_target(sess: &Session, crate_type: config::CrateType) -> bool { match (sess.target.target.options.dynamic_linking, sess.target.target.options.executables, crate_type) { (false, _, config::CrateTypeDylib) => true, (_, false, config::CrateTypeExecutable) => true, _ => false } } fn is_writeable(p: &Path) -> bool { match p.metadata() { Err(..) => true, Ok(m) => !m.permissions().readonly() } } pub fn filename_for_input(sess: &Session, crate_type: config::CrateType, crate_name: &str, outputs: &OutputFilenames) -> PathBuf { let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename); match crate_type { config::CrateTypeRlib => { outputs.out_directory.join(&format!("lib{}.rlib", libname)) } config::CrateTypeDylib => { let (prefix, suffix) = (&sess.target.target.options.dll_prefix, &sess.target.target.options.dll_suffix); outputs.out_directory.join(&format!("{}{}{}", prefix, libname, suffix)) } config::CrateTypeStaticlib => { outputs.out_directory.join(&format!("lib{}.a", libname)) } config::CrateTypeExecutable => { let suffix = &sess.target.target.options.exe_suffix; let out_filename = outputs.path(OutputTypeExe); if suffix.is_empty() { out_filename.to_path_buf() } else { out_filename.with_extension(&suffix[1..]) } } } } fn link_binary_output(sess: &Session, trans: &CrateTranslation, crate_type: config::CrateType, outputs: &OutputFilenames, crate_name: &str) -> PathBuf { let objects = object_filenames(sess, outputs); let out_filename = match outputs.single_output_file { Some(ref file) => file.clone(), None => filename_for_input(sess, crate_type, crate_name, outputs), }; // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers // check this already -- however, the Linux linker will happily overwrite a // read-only file. We should be consistent. for file in objects.iter().chain(Some(&out_filename)) { if !is_writeable(file) { sess.fatal(&format!("output file {} is not writeable -- check its \ permissions", file.display())); } } let tmpdir = TempDir::new("rustc").ok().expect("needs a temp dir"); match crate_type { config::CrateTypeRlib => { link_rlib(sess, Some(trans), &objects, &out_filename, tmpdir.path()).build(); } config::CrateTypeStaticlib => { link_staticlib(sess, &objects, &out_filename, tmpdir.path()); } config::CrateTypeExecutable => { link_natively(sess, trans, false, &objects, &out_filename, outputs, tmpdir.path()); } config::CrateTypeDylib => { link_natively(sess, trans, true, &objects, &out_filename, outputs, tmpdir.path()); } } out_filename } fn object_filenames(sess: &Session, outputs: &OutputFilenames) -> Vec { (0..sess.opts.cg.codegen_units).map(|i| { let ext = format!("{}.o", i); outputs.temp_path(OutputTypeObject).with_extension(&ext) }).collect() } fn archive_search_paths(sess: &Session) -> Vec { let mut search = Vec::new(); sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| { search.push(path.to_path_buf()); FileDoesntMatch }); return search; } fn archive_config<'a>(sess: &'a Session, output: &Path, input: Option<&Path>) -> ArchiveConfig<'a> { ArchiveConfig { sess: sess, dst: output.to_path_buf(), src: input.map(|p| p.to_path_buf()), lib_search_paths: archive_search_paths(sess), ar_prog: get_ar_prog(sess), command_path: command_path(sess), } } // Create an 'rlib' // // An rlib in its current incarnation is essentially a renamed .a file. The // rlib primarily contains the object file of the crate, but it also contains // all of the object files from native libraries. This is done by unzipping // native libraries and inserting all of the contents into this archive. fn link_rlib<'a>(sess: &'a Session, trans: Option<&CrateTranslation>, // None == no metadata/bytecode objects: &[PathBuf], out_filename: &Path, tmpdir: &Path) -> ArchiveBuilder<'a> { info!("preparing rlib from {:?} to {:?}", objects, out_filename); let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None)); for obj in objects { ab.add_file(obj); } for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() { match kind { cstore::NativeStatic => ab.add_native_library(&l).unwrap(), cstore::NativeFramework | cstore::NativeUnknown => {} } } // After adding all files to the archive, we need to update the // symbol table of the archive. ab.update_symbols(); // For OSX/iOS, we must be careful to update symbols only when adding // object files. We're about to start adding non-object files, so run // `ar` now to process the object files. if sess.target.target.options.is_like_osx && !ab.using_llvm() { ab.build(); } // Note that it is important that we add all of our non-object "magical // files" *after* all of the object files in the archive. The reason for // this is as follows: // // * When performing LTO, this archive will be modified to remove // objects from above. The reason for this is described below. // // * When the system linker looks at an archive, it will attempt to // determine the architecture of the archive in order to see whether its // linkable. // // The algorithm for this detection is: iterate over the files in the // archive. Skip magical SYMDEF names. Interpret the first file as an // object file. Read architecture from the object file. // // * As one can probably see, if "metadata" and "foo.bc" were placed // before all of the objects, then the architecture of this archive would // not be correctly inferred once 'foo.o' is removed. // // Basically, all this means is that this code should not move above the // code above. match trans { Some(trans) => { // Instead of putting the metadata in an object file section, rlibs // contain the metadata in a separate file. We use a temp directory // here so concurrent builds in the same directory don't try to use // the same filename for metadata (stomping over one another) let metadata = tmpdir.join(METADATA_FILENAME); match fs::File::create(&metadata).and_then(|mut f| { f.write_all(&trans.metadata) }) { Ok(..) => {} Err(e) => { sess.fatal(&format!("failed to write {}: {}", metadata.display(), e)); } } ab.add_file(&metadata); // For LTO purposes, the bytecode of this library is also inserted // into the archive. If codegen_units > 1, we insert each of the // bitcode files. for obj in objects { // Note that we make sure that the bytecode filename in the // archive is never exactly 16 bytes long by adding a 16 byte // extension to it. This is to work around a bug in LLDB that // would cause it to crash if the name of a file in an archive // was exactly 16 bytes. let bc_filename = obj.with_extension("bc"); let bc_deflated_filename = tmpdir.join({ obj.with_extension("bytecode.deflate").file_name().unwrap() }); let mut bc_data = Vec::new(); match fs::File::open(&bc_filename).and_then(|mut f| { f.read_to_end(&mut bc_data) }) { Ok(..) => {} Err(e) => sess.fatal(&format!("failed to read bytecode: {}", e)) } let bc_data_deflated = flate::deflate_bytes(&bc_data[..]); let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) { Ok(file) => file, Err(e) => { sess.fatal(&format!("failed to create compressed \ bytecode file: {}", e)) } }; match write_rlib_bytecode_object_v1(&mut bc_file_deflated, &bc_data_deflated) { Ok(()) => {} Err(e) => { sess.fatal(&format!("failed to write compressed \ bytecode: {}", e)); } }; ab.add_file(&bc_deflated_filename); // See the bottom of back::write::run_passes for an explanation // of when we do and don't keep .0.bc files around. let user_wants_numbered_bitcode = sess.opts.output_types.contains(&OutputTypeBitcode) && sess.opts.cg.codegen_units > 1; if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode { remove(sess, &bc_filename); } } // After adding all files to the archive, we need to update the // symbol table of the archive. This currently dies on OSX (see // #11162), and isn't necessary there anyway if !sess.target.target.options.is_like_osx || ab.using_llvm() { ab.update_symbols(); } } None => {} } ab } fn write_rlib_bytecode_object_v1(writer: &mut Write, bc_data_deflated: &[u8]) -> io::Result<()> { let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64; try!(writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)); try!(writer.write_all(&[1, 0, 0, 0])); try!(writer.write_all(&[ (bc_data_deflated_size >> 0) as u8, (bc_data_deflated_size >> 8) as u8, (bc_data_deflated_size >> 16) as u8, (bc_data_deflated_size >> 24) as u8, (bc_data_deflated_size >> 32) as u8, (bc_data_deflated_size >> 40) as u8, (bc_data_deflated_size >> 48) as u8, (bc_data_deflated_size >> 56) as u8, ])); try!(writer.write_all(&bc_data_deflated)); let number_of_bytes_written_so_far = RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version mem::size_of_val(&bc_data_deflated_size) + // data size field bc_data_deflated_size as usize; // actual data // If the number of bytes written to the object so far is odd, add a // padding byte to make it even. This works around a crash bug in LLDB // (see issue #15950) if number_of_bytes_written_so_far % 2 == 1 { try!(writer.write_all(&[0])); } return Ok(()); } // Create a static archive // // This is essentially the same thing as an rlib, but it also involves adding // all of the upstream crates' objects into the archive. This will slurp in // all of the native libraries of upstream dependencies as well. // // Additionally, there's no way for us to link dynamic libraries, so we warn // about all dynamic library dependencies that they're not linked in. // // There's no need to include metadata in a static archive, so ensure to not // link in the metadata object file (and also don't prepare the archive with a // metadata file). fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path, tempdir: &Path) { let mut ab = link_rlib(sess, None, objects, out_filename, tempdir); if sess.target.target.options.is_like_osx && !ab.using_llvm() { ab.build(); } if sess.target.target.options.morestack { ab.add_native_library("morestack").unwrap(); } if !sess.target.target.options.no_compiler_rt { ab.add_native_library("compiler-rt").unwrap(); } let crates = sess.cstore.get_used_crates(cstore::RequireStatic); let mut all_native_libs = vec![]; for &(cnum, ref path) in &crates { let ref name = sess.cstore.get_crate_data(cnum).name; let p = match *path { Some(ref p) => p.clone(), None => { sess.err(&format!("could not find rlib for: `{}`", name)); continue } }; ab.add_rlib(&p, &name[..], sess.lto()).unwrap(); let native_libs = csearch::get_native_libraries(&sess.cstore, cnum); all_native_libs.extend(native_libs); } ab.update_symbols(); ab.build(); if !all_native_libs.is_empty() { sess.note("link against the following native artifacts when linking against \ this static library"); sess.note("the order and any duplication can be significant on some platforms, \ and so may need to be preserved"); } for &(kind, ref lib) in &all_native_libs { let name = match kind { cstore::NativeStatic => "static library", cstore::NativeUnknown => "library", cstore::NativeFramework => "framework", }; sess.note(&format!("{}: {}", name, *lib)); } } // Create a dynamic library or executable // // This will invoke the system linker/cc to create the resulting file. This // links to all upstream files as well. fn link_natively(sess: &Session, trans: &CrateTranslation, dylib: bool, objects: &[PathBuf], out_filename: &Path, outputs: &OutputFilenames, tmpdir: &Path) { info!("preparing dylib? ({}) from {:?} to {:?}", dylib, objects, out_filename); // The invocations of cc share some flags across platforms let (pname, mut cmd) = get_linker(sess); cmd.env("PATH", command_path(sess)); let root = sess.target_filesearch(PathKind::Native).get_lib_path(); cmd.args(&sess.target.target.options.pre_link_args); for obj in &sess.target.target.options.pre_link_objects { cmd.arg(root.join(obj)); } { let mut linker = if sess.target.target.options.is_like_msvc { Box::new(MsvcLinker { cmd: &mut cmd, sess: &sess }) as Box } else { Box::new(GnuLinker { cmd: &mut cmd, sess: &sess }) as Box }; link_args(&mut *linker, sess, dylib, tmpdir, trans, objects, out_filename, outputs); if !sess.target.target.options.no_compiler_rt { linker.link_staticlib("compiler-rt"); } } for obj in &sess.target.target.options.post_link_objects { cmd.arg(root.join(obj)); } cmd.args(&sess.target.target.options.post_link_args); if sess.opts.debugging_opts.print_link_args { println!("{:?}", &cmd); } // May have not found libraries in the right formats. sess.abort_if_errors(); // Invoke the system linker info!("{:?}", &cmd); let prog = time(sess.time_passes(), "running linker", (), |()| cmd.output()); match prog { Ok(prog) => { if !prog.status.success() { sess.err(&format!("linking with `{}` failed: {}", pname, prog.status)); sess.note(&format!("{:?}", &cmd)); let mut output = prog.stderr.clone(); output.push_all(&prog.stdout); sess.note(str::from_utf8(&output[..]).unwrap()); sess.abort_if_errors(); } info!("linker stderr:\n{}", String::from_utf8(prog.stderr).unwrap()); info!("linker stdout:\n{}", String::from_utf8(prog.stdout).unwrap()); }, Err(e) => { sess.fatal(&format!("could not exec the linker `{}`: {}", pname, e)); } } // On OSX, debuggers need this utility to get run to do some munging of // the symbols if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo { match Command::new("dsymutil").arg(out_filename).output() { Ok(..) => {} Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)), } } } fn link_args(cmd: &mut Linker, sess: &Session, dylib: bool, tmpdir: &Path, trans: &CrateTranslation, objects: &[PathBuf], out_filename: &Path, outputs: &OutputFilenames) { // The default library location, we need this to find the runtime. // The location of crates will be determined as needed. let lib_path = sess.target_filesearch(PathKind::All).get_lib_path(); // target descriptor let t = &sess.target.target; cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path)); for obj in objects { cmd.add_object(obj); } cmd.output_filename(out_filename); // Stack growth requires statically linking a __morestack function. Note // that this is listed *before* all other libraries. Due to the usage of the // --as-needed flag below, the standard library may only be useful for its // rust_stack_exhausted function. In this case, we must ensure that the // libmorestack.a file appears *before* the standard library (so we put it // at the very front). // // Most of the time this is sufficient, except for when LLVM gets super // clever. If, for example, we have a main function `fn main() {}`, LLVM // will optimize out calls to `__morestack` entirely because the function // doesn't need any stack at all! // // To get around this snag, we specially tell the linker to always include // all contents of this library. This way we're guaranteed that the linker // will include the __morestack symbol 100% of the time, always resolving // references to it even if the object above didn't use it. if t.options.morestack { cmd.link_whole_staticlib("morestack", &[lib_path]); } // When linking a dynamic library, we put the metadata into a section of the // executable. This metadata is in a separate object file from the main // object file, so we link that in here. if dylib { cmd.add_object(&outputs.with_extension("metadata.o")); } // Try to strip as much out of the generated object by removing unused // sections if possible. See more comments in linker.rs cmd.gc_sections(dylib); let used_link_args = sess.cstore.get_used_link_args().borrow(); if !dylib && t.options.position_independent_executables { let empty_vec = Vec::new(); let empty_str = String::new(); let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec); let mut args = args.iter().chain(used_link_args.iter()); let relocation_model = sess.opts.cg.relocation_model.as_ref() .unwrap_or(&empty_str); if (t.options.relocation_model == "pic" || *relocation_model == "pic") && !args.any(|x| *x == "-static") { cmd.position_independent_executable(); } } // Pass optimization flags down to the linker. cmd.optimize(); // Pass debuginfo flags down to the linker. cmd.debuginfo(); // We want to prevent the compiler from accidentally leaking in any system // libraries, so we explicitly ask gcc to not link to any libraries by // default. Note that this does not happen for windows because windows pulls // in some large number of libraries and I couldn't quite figure out which // subset we wanted. cmd.no_default_libraries(); // Take careful note of the ordering of the arguments we pass to the linker // here. Linkers will assume that things on the left depend on things to the // right. Things on the right cannot depend on things on the left. This is // all formally implemented in terms of resolving symbols (libs on the right // resolve unknown symbols of libs on the left, but not vice versa). // // For this reason, we have organized the arguments we pass to the linker as // such: // // 1. The local object that LLVM just generated // 2. Upstream rust libraries // 3. Local native libraries // 4. Upstream native libraries // // This is generally fairly natural, but some may expect 2 and 3 to be // swapped. The reason that all native libraries are put last is that it's // not recommended for a native library to depend on a symbol from a rust // crate. If this is the case then a staticlib crate is recommended, solving // the problem. // // Additionally, it is occasionally the case that upstream rust libraries // depend on a local native library. In the case of libraries such as // lua/glfw/etc the name of the library isn't the same across all platforms, // so only the consumer crate of a library knows the actual name. This means // that downstream crates will provide the #[link] attribute which upstream // crates will depend on. Hence local native libraries are after out // upstream rust crates. // // In theory this means that a symbol in an upstream native library will be // shadowed by a local native library when it wouldn't have been before, but // this kind of behavior is pretty platform specific and generally not // recommended anyway, so I don't think we're shooting ourself in the foot // much with that. add_upstream_rust_crates(cmd, sess, dylib, tmpdir, trans); add_local_native_libraries(cmd, sess); add_upstream_native_libraries(cmd, sess); // # Telling the linker what we're doing if dylib { cmd.build_dylib(out_filename); } // FIXME (#2397): At some point we want to rpath our guesses as to // where extern libraries might live, based on the // addl_lib_search_paths if sess.opts.cg.rpath { let sysroot = sess.sysroot(); let target_triple = &sess.opts.target_triple; let mut get_install_prefix_lib_path = || { let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX"); let tlib = filesearch::relative_target_lib_path(sysroot, target_triple); let mut path = PathBuf::from(install_prefix); path.push(&tlib); path }; let mut rpath_config = RPathConfig { used_crates: sess.cstore.get_used_crates(cstore::RequireDynamic), out_filename: out_filename.to_path_buf(), has_rpath: sess.target.target.options.has_rpath, is_like_osx: sess.target.target.options.is_like_osx, get_install_prefix_lib_path: &mut get_install_prefix_lib_path, }; cmd.args(&rpath::get_rpath_flags(&mut rpath_config)); } // Finally add all the linker arguments provided on the command line along // with any #[link_args] attributes found inside the crate if let Some(ref args) = sess.opts.cg.link_args { cmd.args(args); } cmd.args(&used_link_args); } // # Native library linking // // User-supplied library search paths (-L on the command line). These are // the same paths used to find Rust crates, so some of them may have been // added already by the previous crate linking code. This only allows them // to be found at compile time so it is still entirely up to outside // forces to make sure that library can be found at runtime. // // Also note that the native libraries linked here are only the ones located // in the current crate. Upstream crates with native library dependencies // may have their native library pulled in above. fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) { sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| { match k { PathKind::Framework => { cmd.framework_path(path); } _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); } } FileDoesntMatch }); let libs = sess.cstore.get_used_libraries(); let libs = libs.borrow(); let staticlibs = libs.iter().filter_map(|&(ref l, kind)| { if kind == cstore::NativeStatic {Some(l)} else {None} }); let others = libs.iter().filter(|&&(_, kind)| { kind != cstore::NativeStatic }); // Some platforms take hints about whether a library is static or dynamic. // For those that support this, we ensure we pass the option if the library // was flagged "static" (most defaults are dynamic) to ensure that if // libfoo.a and libfoo.so both exist that the right one is chosen. cmd.hint_static(); let search_path = archive_search_paths(sess); for l in staticlibs { // Here we explicitly ask that the entire archive is included into the // result artifact. For more details see #15460, but the gist is that // the linker will strip away any unused objects in the archive if we // don't otherwise explicitly reference them. This can occur for // libraries which are just providing bindings, libraries with generic // functions, etc. cmd.link_whole_staticlib(l, &search_path); } cmd.hint_dynamic(); for &(ref l, kind) in others { match kind { cstore::NativeUnknown => cmd.link_dylib(l), cstore::NativeFramework => cmd.link_framework(l), cstore::NativeStatic => unreachable!(), } } } // # Rust Crate linking // // Rust crates are not considered at all when creating an rlib output. All // dependencies will be linked when producing the final output (instead of // the intermediate rlib version) fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session, dylib: bool, tmpdir: &Path, trans: &CrateTranslation) { // All of the heavy lifting has previously been accomplished by the // dependency_format module of the compiler. This is just crawling the // output of that module, adding crates as necessary. // // Linking to a rlib involves just passing it to the linker (the linker // will slurp up the object files inside), and linking to a dynamic library // involves just passing the right -l flag. let data = if dylib { trans.crate_formats.get(&config::CrateTypeDylib).unwrap() } else { trans.crate_formats.get(&config::CrateTypeExecutable).unwrap() }; // Invoke get_used_crates to ensure that we get a topological sorting of // crates. let deps = sess.cstore.get_used_crates(cstore::RequireDynamic); for &(cnum, _) in &deps { // We may not pass all crates through to the linker. Some crates may // appear statically in an existing dylib, meaning we'll pick up all the // symbols from the dylib. let kind = match data[cnum as usize - 1] { Some(t) => t, None => continue }; let src = sess.cstore.get_used_crate_source(cnum).unwrap(); match kind { cstore::RequireDynamic => { add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0) } cstore::RequireStatic => { add_static_crate(cmd, sess, tmpdir, dylib, &src.rlib.unwrap().0) } } } // Converts a library file-stem into a cc -l argument fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str { if stem.starts_with("lib") && !config.target.options.is_like_windows { &stem[3..] } else { stem } } // Adds the static "rlib" versions of all crates to the command line. // There's a bit of magic which happens here specifically related to LTO and // dynamic libraries. Specifically: // // * For LTO, we remove upstream object files. // * For dylibs we remove metadata and bytecode from upstream rlibs // // When performing LTO, all of the bytecode from the upstream libraries has // already been included in our object file output. As a result we need to // remove the object files in the upstream libraries so the linker doesn't // try to include them twice (or whine about duplicate symbols). We must // continue to include the rest of the rlib, however, as it may contain // static native libraries which must be linked in. // // When making a dynamic library, linkers by default don't include any // object files in an archive if they're not necessary to resolve the link. // We basically want to convert the archive (rlib) to a dylib, though, so we // *do* want everything included in the output, regardless of whether the // linker thinks it's needed or not. As a result we must use the // --whole-archive option (or the platform equivalent). When using this // option the linker will fail if there are non-objects in the archive (such // as our own metadata and/or bytecode). All in all, for rlibs to be // entirely included in dylibs, we need to remove all non-object files. // // Note, however, that if we're not doing LTO or we're not producing a dylib // (aka we're making an executable), we can just pass the rlib blindly to // the linker (fast) because it's fine if it's not actually included as // we're at the end of the dependency chain. fn add_static_crate(cmd: &mut Linker, sess: &Session, tmpdir: &Path, dylib: bool, cratepath: &Path) { if !sess.lto() && !dylib { cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath)); return } let dst = tmpdir.join(cratepath.file_name().unwrap()); let name = cratepath.file_name().unwrap().to_str().unwrap(); let name = &name[3..name.len() - 5]; // chop off lib/.rlib time(sess.time_passes(), &format!("altering {}.rlib", name), (), |()| { let cfg = archive_config(sess, &dst, Some(cratepath)); let mut archive = ArchiveBuilder::new(cfg); archive.remove_file(METADATA_FILENAME); archive.update_symbols(); let mut any_objects = false; for f in archive.src_files() { if f.ends_with("bytecode.deflate") { archive.remove_file(&f); continue } let canonical = f.replace("-", "_"); let canonical_name = name.replace("-", "_"); if sess.lto() && canonical.starts_with(&canonical_name) && canonical.ends_with(".o") { let num = &f[name.len()..f.len() - 2]; if num.len() > 0 && num[1..].parse::().is_ok() { archive.remove_file(&f); continue } } any_objects = true; } if any_objects { archive.build(); cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst)); } }); } // Same thing as above, but for dynamic crates instead of static crates. fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) { // If we're performing LTO, then it should have been previously required // that all upstream rust dependencies were available in an rlib format. assert!(!sess.lto()); // Just need to tell the linker about where the library lives and // what its name is let parent = cratepath.parent(); if let Some(dir) = parent { cmd.include_path(&fix_windows_verbatim_for_gcc(dir)); } let filestem = cratepath.file_stem().unwrap().to_str().unwrap(); cmd.link_rust_dylib(&unlib(&sess.target, filestem), parent.unwrap_or(Path::new(""))); } } // Link in all of our upstream crates' native dependencies. Remember that // all of these upstream native dependencies are all non-static // dependencies. We've got two cases then: // // 1. The upstream crate is an rlib. In this case we *must* link in the // native dependency because the rlib is just an archive. // // 2. The upstream crate is a dylib. In order to use the dylib, we have to // have the dependency present on the system somewhere. Thus, we don't // gain a whole lot from not linking in the dynamic dependency to this // crate as well. // // The use case for this is a little subtle. In theory the native // dependencies of a crate are purely an implementation detail of the crate // itself, but the problem arises with generic and inlined functions. If a // generic function calls a native function, then the generic function must // be instantiated in the target crate, meaning that the native symbol must // also be resolved in the target crate. fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) { // Be sure to use a topological sorting of crates because there may be // interdependencies between native libraries. When passing -nodefaultlibs, // for example, almost all native libraries depend on libc, so we have to // make sure that's all the way at the right (liblibc is near the base of // the dependency chain). // // This passes RequireStatic, but the actual requirement doesn't matter, // we're just getting an ordering of crate numbers, we're not worried about // the paths. let crates = sess.cstore.get_used_crates(cstore::RequireStatic); for (cnum, _) in crates { let libs = csearch::get_native_libraries(&sess.cstore, cnum); for &(kind, ref lib) in &libs { match kind { cstore::NativeUnknown => cmd.link_dylib(lib), cstore::NativeFramework => cmd.link_framework(lib), cstore::NativeStatic => { sess.bug("statics shouldn't be propagated"); } } } } }