1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use super::archive::{Archive, ArchiveBuilder, ArchiveConfig, METADATA_FILENAME};
12 use super::linker::{Linker, GnuLinker, MsvcLinker};
13 use super::rpath::RPathConfig;
18 use session::config::NoDebugInfo;
19 use session::config::{OutputFilenames, Input, OutputTypeBitcode, OutputTypeExe, OutputTypeObject};
20 use session::search_paths::PathKind;
22 use metadata::common::LinkMeta;
23 use metadata::{encoder, cstore, filesearch, csearch, creader};
24 use metadata::filesearch::FileDoesntMatch;
25 use middle::ty::{self, Ty};
26 use rustc::ast_map::{PathElem, PathElems, PathName};
27 use trans::{CrateContext, CrateTranslation, gensym_name};
28 use util::common::time;
29 use util::sha2::{Digest, Sha256};
30 use util::fs::fix_windows_verbatim_for_gcc;
31 use rustc_back::tempdir::TempDir;
34 use std::ffi::OsString;
35 use std::fs::{self, PathExt};
36 use std::io::{self, Read, Write};
38 use std::path::{Path, PathBuf};
39 use std::process::Command;
42 use serialize::hex::ToHex;
44 use syntax::attr::AttrMetaMethods;
45 use syntax::codemap::Span;
46 use syntax::parse::token;
48 // RLIB LLVM-BYTECODE OBJECT LAYOUT
51 // 0..10 "RUST_OBJECT" encoded in ASCII
52 // 11..14 format version as little-endian u32
53 // 15..22 size in bytes of deflate compressed LLVM bitcode as
55 // 23.. compressed LLVM bitcode
57 // This is the "magic number" expected at the beginning of a LLVM bytecode
59 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
61 // The version number this compiler will write to bytecode objects in rlibs
62 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
64 // The offset in bytes the bytecode object format version number can be found at
65 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
67 // The offset in bytes the size of the compressed bytecode can be found at in
69 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
70 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
72 // The offset in bytes the compressed LLVM bytecode can be found at in format
74 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
75 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
79 * Name mangling and its relationship to metadata. This is complex. Read
82 * The semantic model of Rust linkage is, broadly, that "there's no global
83 * namespace" between crates. Our aim is to preserve the illusion of this
84 * model despite the fact that it's not *quite* possible to implement on
85 * modern linkers. We initially didn't use system linkers at all, but have
86 * been convinced of their utility.
88 * There are a few issues to handle:
90 * - Linkers operate on a flat namespace, so we have to flatten names.
91 * We do this using the C++ namespace-mangling technique. Foo::bar
94 * - Symbols with the same name but different types need to get different
95 * linkage-names. We do this by hashing a string-encoding of the type into
96 * a fixed-size (currently 16-byte hex) cryptographic hash function (CHF:
97 * we use SHA256) to "prevent collisions". This is not airtight but 16 hex
98 * digits on uniform probability means you're going to need 2**32 same-name
99 * symbols in the same process before you're even hitting birthday-paradox
100 * collision probability.
102 * - Symbols in different crates but with same names "within" the crate need
103 * to get different linkage-names.
105 * - The hash shown in the filename needs to be predictable and stable for
106 * build tooling integration. It also needs to be using a hash function
107 * which is easy to use from Python, make, etc.
109 * So here is what we do:
111 * - Consider the package id; every crate has one (specified with crate_id
112 * attribute). If a package id isn't provided explicitly, we infer a
113 * versionless one from the output name. The version will end up being 0.0
114 * in this case. CNAME and CVERS are taken from this package id. For
115 * example, github.com/mozilla/CNAME#CVERS.
117 * - Define CMH as SHA256(crateid).
119 * - Define CMH8 as the first 8 characters of CMH.
121 * - Compile our crate to lib CNAME-CMH8-CVERS.so
123 * - Define STH(sym) as SHA256(CMH, type_str(sym))
125 * - Suffix a mangled sym with ::STH@CVERS, so that it is unique in the
126 * name, non-name metadata, and type sense, and versioned in the way
127 * system linkers understand.
130 pub fn find_crate_name(sess: Option<&Session>,
131 attrs: &[ast::Attribute],
132 input: &Input) -> String {
133 let validate = |s: String, span: Option<Span>| {
134 creader::validate_crate_name(sess, &s[..], span);
138 // Look in attributes 100% of the time to make sure the attribute is marked
139 // as used. After doing this, however, we still prioritize a crate name from
140 // the command line over one found in the #[crate_name] attribute. If we
141 // find both we ensure that they're the same later on as well.
142 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
143 .and_then(|at| at.value_str().map(|s| (at, s)));
145 if let Some(sess) = sess {
146 if let Some(ref s) = sess.opts.crate_name {
147 if let Some((attr, ref name)) = attr_crate_name {
149 let msg = format!("--crate-name and #[crate_name] are \
150 required to match, but `{}` != `{}`",
152 sess.span_err(attr.span, &msg[..]);
155 return validate(s.clone(), None);
159 if let Some((attr, s)) = attr_crate_name {
160 return validate(s.to_string(), Some(attr.span));
162 if let Input::File(ref path) = *input {
163 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
164 if s.starts_with("-") {
165 let msg = format!("crate names cannot start with a `-`, but \
166 `{}` has a leading hyphen", s);
167 if let Some(sess) = sess {
171 return validate(s.replace("-", "_"), None);
176 "rust_out".to_string()
179 pub fn build_link_meta(sess: &Session, krate: &ast::Crate,
180 name: String) -> LinkMeta {
183 crate_hash: Svh::calculate(&sess.opts.cg.metadata, krate),
189 fn truncated_hash_result(symbol_hasher: &mut Sha256) -> String {
190 let output = symbol_hasher.result_bytes();
191 // 64 bits should be enough to avoid collisions.
192 output[.. 8].to_hex().to_string()
196 // This calculates STH for a symbol, as defined above
197 fn symbol_hash<'tcx>(tcx: &ty::ctxt<'tcx>,
198 symbol_hasher: &mut Sha256,
200 link_meta: &LinkMeta)
202 // NB: do *not* use abbrevs here as we want the symbol names
203 // to be independent of one another in the crate.
205 symbol_hasher.reset();
206 symbol_hasher.input_str(&link_meta.crate_name);
207 symbol_hasher.input_str("-");
208 symbol_hasher.input_str(link_meta.crate_hash.as_str());
209 for meta in tcx.sess.crate_metadata.borrow().iter() {
210 symbol_hasher.input_str(&meta[..]);
212 symbol_hasher.input_str("-");
213 symbol_hasher.input_str(&encoder::encoded_ty(tcx, t));
214 // Prefix with 'h' so that it never blends into adjacent digits
215 let mut hash = String::from("h");
216 hash.push_str(&truncated_hash_result(symbol_hasher));
220 fn get_symbol_hash<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) -> String {
221 match ccx.type_hashcodes().borrow().get(&t) {
222 Some(h) => return h.to_string(),
226 let mut symbol_hasher = ccx.symbol_hasher().borrow_mut();
227 let hash = symbol_hash(ccx.tcx(), &mut *symbol_hasher, t, ccx.link_meta());
228 ccx.type_hashcodes().borrow_mut().insert(t, hash.clone());
233 // Name sanitation. LLVM will happily accept identifiers with weird names, but
235 // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $
236 pub fn sanitize(s: &str) -> String {
237 let mut result = String::new();
240 // Escape these with $ sequences
241 '@' => result.push_str("$SP$"),
242 '*' => result.push_str("$BP$"),
243 '&' => result.push_str("$RF$"),
244 '<' => result.push_str("$LT$"),
245 '>' => result.push_str("$GT$"),
246 '(' => result.push_str("$LP$"),
247 ')' => result.push_str("$RP$"),
248 ',' => result.push_str("$C$"),
250 // '.' doesn't occur in types and functions, so reuse it
252 '-' | ':' => result.push('.'),
254 // These are legal symbols
258 | '_' | '.' | '$' => result.push(c),
262 for c in c.escape_unicode().skip(1) {
265 '}' => result.push('$'),
273 // Underscore-qualify anything that didn't start as an ident.
274 if !result.is_empty() &&
275 result.as_bytes()[0] != '_' as u8 &&
276 ! (result.as_bytes()[0] as char).is_xid_start() {
277 return format!("_{}", &result[..]);
283 pub fn mangle<PI: Iterator<Item=PathElem>>(path: PI,
284 hash: Option<&str>) -> String {
285 // Follow C++ namespace-mangling style, see
286 // http://en.wikipedia.org/wiki/Name_mangling for more info.
288 // It turns out that on OSX you can actually have arbitrary symbols in
289 // function names (at least when given to LLVM), but this is not possible
290 // when using unix's linker. Perhaps one day when we just use a linker from LLVM
291 // we won't need to do this name mangling. The problem with name mangling is
292 // that it seriously limits the available characters. For example we can't
293 // have things like &T in symbol names when one would theoretically
294 // want them for things like impls of traits on that type.
296 // To be able to work on all platforms and get *some* reasonable output, we
297 // use C++ name-mangling.
299 let mut n = String::from("_ZN"); // _Z == Begin name-sequence, N == nested
301 fn push(n: &mut String, s: &str) {
302 let sani = sanitize(s);
303 n.push_str(&format!("{}{}", sani.len(), sani));
306 // First, connect each component with <len, name> pairs.
308 push(&mut n, &token::get_name(e.name()))
312 Some(s) => push(&mut n, s),
316 n.push('E'); // End name-sequence.
320 pub fn exported_name(path: PathElems, hash: &str) -> String {
321 mangle(path, Some(hash))
324 pub fn mangle_exported_name<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, path: PathElems,
325 t: Ty<'tcx>, id: ast::NodeId) -> String {
326 let mut hash = get_symbol_hash(ccx, t);
328 // Paths can be completely identical for different nodes,
329 // e.g. `fn foo() { { fn a() {} } { fn a() {} } }`, so we
330 // generate unique characters from the node id. For now
331 // hopefully 3 characters is enough to avoid collisions.
332 const EXTRA_CHARS: &'static str =
333 "abcdefghijklmnopqrstuvwxyz\
334 ABCDEFGHIJKLMNOPQRSTUVWXYZ\
336 let id = id as usize;
337 let extra1 = id % EXTRA_CHARS.len();
338 let id = id / EXTRA_CHARS.len();
339 let extra2 = id % EXTRA_CHARS.len();
340 let id = id / EXTRA_CHARS.len();
341 let extra3 = id % EXTRA_CHARS.len();
342 hash.push(EXTRA_CHARS.as_bytes()[extra1] as char);
343 hash.push(EXTRA_CHARS.as_bytes()[extra2] as char);
344 hash.push(EXTRA_CHARS.as_bytes()[extra3] as char);
346 exported_name(path, &hash[..])
349 pub fn mangle_internal_name_by_type_and_seq<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
351 name: &str) -> String {
352 let path = [PathName(token::intern(&t.to_string())),
354 let hash = get_symbol_hash(ccx, t);
355 mangle(path.iter().cloned(), Some(&hash[..]))
358 pub fn mangle_internal_name_by_path_and_seq(path: PathElems, flav: &str) -> String {
359 mangle(path.chain(Some(gensym_name(flav))), None)
362 pub fn get_linker(sess: &Session) -> (String, Command) {
363 if let Some(ref linker) = sess.opts.cg.linker {
364 (linker.clone(), Command::new(linker))
365 } else if sess.target.target.options.is_like_msvc {
366 ("link.exe".to_string(), msvc::link_exe_cmd(sess))
368 (sess.target.target.options.linker.clone(),
369 Command::new(&sess.target.target.options.linker))
373 pub fn get_ar_prog(sess: &Session) -> String {
374 sess.opts.cg.ar.clone().unwrap_or_else(|| {
375 sess.target.target.options.ar.clone()
379 fn command_path(sess: &Session) -> OsString {
380 // The compiler's sysroot often has some bundled tools, so add it to the
381 // PATH for the child.
382 let mut new_path = sess.host_filesearch(PathKind::All)
383 .get_tools_search_paths();
384 if let Some(path) = env::var_os("PATH") {
385 new_path.extend(env::split_paths(&path));
387 env::join_paths(new_path).unwrap()
390 pub fn remove(sess: &Session, path: &Path) {
391 match fs::remove_file(path) {
394 sess.err(&format!("failed to remove {}: {}",
401 /// Perform the linkage portion of the compilation phase. This will generate all
402 /// of the requested outputs for this compilation session.
403 pub fn link_binary(sess: &Session,
404 trans: &CrateTranslation,
405 outputs: &OutputFilenames,
406 crate_name: &str) -> Vec<PathBuf> {
407 let mut out_filenames = Vec::new();
408 for &crate_type in sess.crate_types.borrow().iter() {
409 if invalid_output_for_target(sess, crate_type) {
410 sess.bug(&format!("invalid output type `{:?}` for target os `{}`",
411 crate_type, sess.opts.target_triple));
413 let out_file = link_binary_output(sess, trans, crate_type, outputs,
415 out_filenames.push(out_file);
418 // Remove the temporary object file and metadata if we aren't saving temps
419 if !sess.opts.cg.save_temps {
420 for obj in object_filenames(sess, outputs) {
423 remove(sess, &outputs.with_extension("metadata.o"));
430 /// Returns default crate type for target
432 /// Default crate type is used when crate type isn't provided neither
433 /// through cmd line arguments nor through crate attributes
435 /// It is CrateTypeExecutable for all platforms but iOS as there is no
436 /// way to run iOS binaries anyway without jailbreaking and
437 /// interaction with Rust code through static library is the only
439 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
440 if !sess.target.target.options.executables {
441 config::CrateTypeStaticlib
443 config::CrateTypeExecutable
447 /// Checks if target supports crate_type as output
448 pub fn invalid_output_for_target(sess: &Session,
449 crate_type: config::CrateType) -> bool {
450 match (sess.target.target.options.dynamic_linking,
451 sess.target.target.options.executables, crate_type) {
452 (false, _, config::CrateTypeDylib) => true,
453 (_, false, config::CrateTypeExecutable) => true,
458 fn is_writeable(p: &Path) -> bool {
461 Ok(m) => !m.permissions().readonly()
465 pub fn filename_for_input(sess: &Session,
466 crate_type: config::CrateType,
468 outputs: &OutputFilenames) -> PathBuf {
469 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
471 config::CrateTypeRlib => {
472 outputs.out_directory.join(&format!("lib{}.rlib", libname))
474 config::CrateTypeDylib => {
475 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
476 &sess.target.target.options.dll_suffix);
477 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
480 config::CrateTypeStaticlib => {
481 outputs.out_directory.join(&format!("lib{}.a", libname))
483 config::CrateTypeExecutable => {
484 let suffix = &sess.target.target.options.exe_suffix;
485 let out_filename = outputs.path(OutputTypeExe);
486 if suffix.is_empty() {
487 out_filename.to_path_buf()
489 out_filename.with_extension(&suffix[1..])
495 fn link_binary_output(sess: &Session,
496 trans: &CrateTranslation,
497 crate_type: config::CrateType,
498 outputs: &OutputFilenames,
499 crate_name: &str) -> PathBuf {
500 let objects = object_filenames(sess, outputs);
501 let out_filename = match outputs.single_output_file {
502 Some(ref file) => file.clone(),
503 None => filename_for_input(sess, crate_type, crate_name, outputs),
506 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
507 // check this already -- however, the Linux linker will happily overwrite a
508 // read-only file. We should be consistent.
509 for file in objects.iter().chain(Some(&out_filename)) {
510 if !is_writeable(file) {
511 sess.fatal(&format!("output file {} is not writeable -- check its \
512 permissions", file.display()));
517 config::CrateTypeRlib => {
518 link_rlib(sess, Some(trans), &objects, &out_filename).build();
520 config::CrateTypeStaticlib => {
521 link_staticlib(sess, &objects, &out_filename);
523 config::CrateTypeExecutable => {
524 link_natively(sess, trans, false, &objects, &out_filename, outputs);
526 config::CrateTypeDylib => {
527 link_natively(sess, trans, true, &objects, &out_filename, outputs);
534 fn object_filenames(sess: &Session, outputs: &OutputFilenames) -> Vec<PathBuf> {
535 (0..sess.opts.cg.codegen_units).map(|i| {
536 let ext = format!("{}.o", i);
537 outputs.temp_path(OutputTypeObject).with_extension(&ext)
541 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
542 let mut search = Vec::new();
543 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
544 search.push(path.to_path_buf());
550 fn archive_config<'a>(sess: &'a Session,
551 output: &Path) -> ArchiveConfig<'a> {
553 handler: &sess.diagnostic().handler,
554 dst: output.to_path_buf(),
555 lib_search_paths: archive_search_paths(sess),
556 slib_prefix: sess.target.target.options.staticlib_prefix.clone(),
557 slib_suffix: sess.target.target.options.staticlib_suffix.clone(),
558 ar_prog: get_ar_prog(sess),
559 command_path: command_path(sess),
565 // An rlib in its current incarnation is essentially a renamed .a file. The
566 // rlib primarily contains the object file of the crate, but it also contains
567 // all of the object files from native libraries. This is done by unzipping
568 // native libraries and inserting all of the contents into this archive.
569 fn link_rlib<'a>(sess: &'a Session,
570 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
572 out_filename: &Path) -> ArchiveBuilder<'a> {
573 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
574 let mut ab = ArchiveBuilder::create(archive_config(sess, out_filename));
576 ab.add_file(obj).unwrap();
579 for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() {
581 cstore::NativeStatic => ab.add_native_library(&l).unwrap(),
582 cstore::NativeFramework | cstore::NativeUnknown => {}
586 // After adding all files to the archive, we need to update the
587 // symbol table of the archive.
590 let mut ab = match sess.target.target.options.is_like_osx {
591 // For OSX/iOS, we must be careful to update symbols only when adding
592 // object files. We're about to start adding non-object files, so run
593 // `ar` now to process the object files.
594 true => ab.build().extend(),
598 // Note that it is important that we add all of our non-object "magical
599 // files" *after* all of the object files in the archive. The reason for
600 // this is as follows:
602 // * When performing LTO, this archive will be modified to remove
603 // objects from above. The reason for this is described below.
605 // * When the system linker looks at an archive, it will attempt to
606 // determine the architecture of the archive in order to see whether its
609 // The algorithm for this detection is: iterate over the files in the
610 // archive. Skip magical SYMDEF names. Interpret the first file as an
611 // object file. Read architecture from the object file.
613 // * As one can probably see, if "metadata" and "foo.bc" were placed
614 // before all of the objects, then the architecture of this archive would
615 // not be correctly inferred once 'foo.o' is removed.
617 // Basically, all this means is that this code should not move above the
621 // Instead of putting the metadata in an object file section, rlibs
622 // contain the metadata in a separate file. We use a temp directory
623 // here so concurrent builds in the same directory don't try to use
624 // the same filename for metadata (stomping over one another)
625 let tmpdir = TempDir::new("rustc").ok().expect("needs a temp dir");
626 let metadata = tmpdir.path().join(METADATA_FILENAME);
627 match fs::File::create(&metadata).and_then(|mut f| {
628 f.write_all(&trans.metadata)
632 sess.fatal(&format!("failed to write {}: {}",
633 metadata.display(), e));
636 ab.add_file(&metadata).unwrap();
637 remove(sess, &metadata);
639 // For LTO purposes, the bytecode of this library is also inserted
640 // into the archive. If codegen_units > 1, we insert each of the
643 // Note that we make sure that the bytecode filename in the
644 // archive is never exactly 16 bytes long by adding a 16 byte
645 // extension to it. This is to work around a bug in LLDB that
646 // would cause it to crash if the name of a file in an archive
647 // was exactly 16 bytes.
648 let bc_filename = obj.with_extension("bc");
649 let bc_deflated_filename = obj.with_extension("bytecode.deflate");
651 let mut bc_data = Vec::new();
652 match fs::File::open(&bc_filename).and_then(|mut f| {
653 f.read_to_end(&mut bc_data)
656 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
660 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
662 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
665 sess.fatal(&format!("failed to create compressed \
666 bytecode file: {}", e))
670 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
674 sess.fatal(&format!("failed to write compressed \
679 ab.add_file(&bc_deflated_filename).unwrap();
680 remove(sess, &bc_deflated_filename);
682 // See the bottom of back::write::run_passes for an explanation
683 // of when we do and don't keep .0.bc files around.
684 let user_wants_numbered_bitcode =
685 sess.opts.output_types.contains(&OutputTypeBitcode) &&
686 sess.opts.cg.codegen_units > 1;
687 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
688 remove(sess, &bc_filename);
692 // After adding all files to the archive, we need to update the
693 // symbol table of the archive. This currently dies on OSX (see
694 // #11162), and isn't necessary there anyway
695 if !sess.target.target.options.is_like_osx {
706 fn write_rlib_bytecode_object_v1(writer: &mut Write,
707 bc_data_deflated: &[u8]) -> io::Result<()> {
708 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
710 try!(writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC));
711 try!(writer.write_all(&[1, 0, 0, 0]));
712 try!(writer.write_all(&[
713 (bc_data_deflated_size >> 0) as u8,
714 (bc_data_deflated_size >> 8) as u8,
715 (bc_data_deflated_size >> 16) as u8,
716 (bc_data_deflated_size >> 24) as u8,
717 (bc_data_deflated_size >> 32) as u8,
718 (bc_data_deflated_size >> 40) as u8,
719 (bc_data_deflated_size >> 48) as u8,
720 (bc_data_deflated_size >> 56) as u8,
722 try!(writer.write_all(&bc_data_deflated));
724 let number_of_bytes_written_so_far =
725 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
726 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
727 mem::size_of_val(&bc_data_deflated_size) + // data size field
728 bc_data_deflated_size as usize; // actual data
730 // If the number of bytes written to the object so far is odd, add a
731 // padding byte to make it even. This works around a crash bug in LLDB
732 // (see issue #15950)
733 if number_of_bytes_written_so_far % 2 == 1 {
734 try!(writer.write_all(&[0]));
740 // Create a static archive
742 // This is essentially the same thing as an rlib, but it also involves adding
743 // all of the upstream crates' objects into the archive. This will slurp in
744 // all of the native libraries of upstream dependencies as well.
746 // Additionally, there's no way for us to link dynamic libraries, so we warn
747 // about all dynamic library dependencies that they're not linked in.
749 // There's no need to include metadata in a static archive, so ensure to not
750 // link in the metadata object file (and also don't prepare the archive with a
752 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path) {
753 let ab = link_rlib(sess, None, objects, out_filename);
754 let mut ab = match sess.target.target.options.is_like_osx {
755 true => ab.build().extend(),
758 if sess.target.target.options.morestack {
759 ab.add_native_library("morestack").unwrap();
761 if !sess.target.target.options.no_compiler_rt {
762 ab.add_native_library("compiler-rt").unwrap();
765 let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
766 let mut all_native_libs = vec![];
768 for &(cnum, ref path) in &crates {
769 let ref name = sess.cstore.get_crate_data(cnum).name;
770 let p = match *path {
771 Some(ref p) => p.clone(), None => {
772 sess.err(&format!("could not find rlib for: `{}`",
777 ab.add_rlib(&p, &name[..], sess.lto()).unwrap();
779 let native_libs = csearch::get_native_libraries(&sess.cstore, cnum);
780 all_native_libs.extend(native_libs);
786 if !all_native_libs.is_empty() {
787 sess.note("link against the following native artifacts when linking against \
788 this static library");
789 sess.note("the order and any duplication can be significant on some platforms, \
790 and so may need to be preserved");
793 for &(kind, ref lib) in &all_native_libs {
794 let name = match kind {
795 cstore::NativeStatic => "static library",
796 cstore::NativeUnknown => "library",
797 cstore::NativeFramework => "framework",
799 sess.note(&format!("{}: {}", name, *lib));
803 // Create a dynamic library or executable
805 // This will invoke the system linker/cc to create the resulting file. This
806 // links to all upstream files as well.
807 fn link_natively(sess: &Session, trans: &CrateTranslation, dylib: bool,
808 objects: &[PathBuf], out_filename: &Path,
809 outputs: &OutputFilenames) {
810 info!("preparing dylib? ({}) from {:?} to {:?}", dylib, objects,
812 let tmpdir = TempDir::new("rustc").ok().expect("needs a temp dir");
814 // The invocations of cc share some flags across platforms
815 let (pname, mut cmd) = get_linker(sess);
816 cmd.env("PATH", command_path(sess));
818 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
819 cmd.args(&sess.target.target.options.pre_link_args);
820 for obj in &sess.target.target.options.pre_link_objects {
821 cmd.arg(root.join(obj));
825 let mut linker = if sess.target.target.options.is_like_msvc {
826 Box::new(MsvcLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
828 Box::new(GnuLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
830 link_args(&mut *linker, sess, dylib, tmpdir.path(),
831 trans, objects, out_filename, outputs);
832 if !sess.target.target.options.no_compiler_rt {
833 linker.link_staticlib("compiler-rt");
836 for obj in &sess.target.target.options.post_link_objects {
837 cmd.arg(root.join(obj));
839 cmd.args(&sess.target.target.options.post_link_args);
841 if sess.opts.debugging_opts.print_link_args {
842 println!("{:?}", &cmd);
845 // May have not found libraries in the right formats.
846 sess.abort_if_errors();
848 // Invoke the system linker
850 let prog = time(sess.time_passes(), "running linker", (), |()| cmd.output());
853 if !prog.status.success() {
854 sess.err(&format!("linking with `{}` failed: {}",
857 sess.note(&format!("{:?}", &cmd));
858 let mut output = prog.stderr.clone();
859 output.push_all(&prog.stdout);
860 sess.note(str::from_utf8(&output[..]).unwrap());
861 sess.abort_if_errors();
863 info!("linker stderr:\n{}", String::from_utf8(prog.stderr).unwrap());
864 info!("linker stdout:\n{}", String::from_utf8(prog.stdout).unwrap());
867 sess.fatal(&format!("could not exec the linker `{}`: {}", pname, e));
872 // On OSX, debuggers need this utility to get run to do some munging of
874 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
875 match Command::new("dsymutil").arg(out_filename).output() {
877 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
882 fn link_args(cmd: &mut Linker,
886 trans: &CrateTranslation,
889 outputs: &OutputFilenames) {
891 // The default library location, we need this to find the runtime.
892 // The location of crates will be determined as needed.
893 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
896 let t = &sess.target.target;
898 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
902 cmd.output_filename(out_filename);
904 // Stack growth requires statically linking a __morestack function. Note
905 // that this is listed *before* all other libraries. Due to the usage of the
906 // --as-needed flag below, the standard library may only be useful for its
907 // rust_stack_exhausted function. In this case, we must ensure that the
908 // libmorestack.a file appears *before* the standard library (so we put it
909 // at the very front).
911 // Most of the time this is sufficient, except for when LLVM gets super
912 // clever. If, for example, we have a main function `fn main() {}`, LLVM
913 // will optimize out calls to `__morestack` entirely because the function
914 // doesn't need any stack at all!
916 // To get around this snag, we specially tell the linker to always include
917 // all contents of this library. This way we're guaranteed that the linker
918 // will include the __morestack symbol 100% of the time, always resolving
919 // references to it even if the object above didn't use it.
920 if t.options.morestack {
921 cmd.link_whole_staticlib("morestack", &[lib_path]);
924 // When linking a dynamic library, we put the metadata into a section of the
925 // executable. This metadata is in a separate object file from the main
926 // object file, so we link that in here.
928 cmd.add_object(&outputs.with_extension("metadata.o"));
931 // Try to strip as much out of the generated object by removing unused
932 // sections if possible. See more comments in linker.rs
933 cmd.gc_sections(dylib);
935 let used_link_args = sess.cstore.get_used_link_args().borrow();
937 if !dylib && t.options.position_independent_executables {
938 let empty_vec = Vec::new();
939 let empty_str = String::new();
940 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
941 let mut args = args.iter().chain(used_link_args.iter());
942 let relocation_model = sess.opts.cg.relocation_model.as_ref()
943 .unwrap_or(&empty_str);
944 if (t.options.relocation_model == "pic" || *relocation_model == "pic")
945 && !args.any(|x| *x == "-static") {
946 cmd.position_independent_executable();
950 // Pass optimization flags down to the linker.
953 // We want to prevent the compiler from accidentally leaking in any system
954 // libraries, so we explicitly ask gcc to not link to any libraries by
955 // default. Note that this does not happen for windows because windows pulls
956 // in some large number of libraries and I couldn't quite figure out which
958 cmd.no_default_libraries();
960 // Take careful note of the ordering of the arguments we pass to the linker
961 // here. Linkers will assume that things on the left depend on things to the
962 // right. Things on the right cannot depend on things on the left. This is
963 // all formally implemented in terms of resolving symbols (libs on the right
964 // resolve unknown symbols of libs on the left, but not vice versa).
966 // For this reason, we have organized the arguments we pass to the linker as
969 // 1. The local object that LLVM just generated
970 // 2. Upstream rust libraries
971 // 3. Local native libraries
972 // 4. Upstream native libraries
974 // This is generally fairly natural, but some may expect 2 and 3 to be
975 // swapped. The reason that all native libraries are put last is that it's
976 // not recommended for a native library to depend on a symbol from a rust
977 // crate. If this is the case then a staticlib crate is recommended, solving
980 // Additionally, it is occasionally the case that upstream rust libraries
981 // depend on a local native library. In the case of libraries such as
982 // lua/glfw/etc the name of the library isn't the same across all platforms,
983 // so only the consumer crate of a library knows the actual name. This means
984 // that downstream crates will provide the #[link] attribute which upstream
985 // crates will depend on. Hence local native libraries are after out
986 // upstream rust crates.
988 // In theory this means that a symbol in an upstream native library will be
989 // shadowed by a local native library when it wouldn't have been before, but
990 // this kind of behavior is pretty platform specific and generally not
991 // recommended anyway, so I don't think we're shooting ourself in the foot
993 add_upstream_rust_crates(cmd, sess, dylib, tmpdir, trans);
994 add_local_native_libraries(cmd, sess);
995 add_upstream_native_libraries(cmd, sess);
997 // # Telling the linker what we're doing
1000 cmd.build_dylib(out_filename);
1003 // FIXME (#2397): At some point we want to rpath our guesses as to
1004 // where extern libraries might live, based on the
1005 // addl_lib_search_paths
1006 if sess.opts.cg.rpath {
1007 let sysroot = sess.sysroot();
1008 let target_triple = &sess.opts.target_triple;
1009 let mut get_install_prefix_lib_path = || {
1010 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1011 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1012 let mut path = PathBuf::from(install_prefix);
1017 let mut rpath_config = RPathConfig {
1018 used_crates: sess.cstore.get_used_crates(cstore::RequireDynamic),
1019 out_filename: out_filename.to_path_buf(),
1020 has_rpath: sess.target.target.options.has_rpath,
1021 is_like_osx: sess.target.target.options.is_like_osx,
1022 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1024 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1027 // Finally add all the linker arguments provided on the command line along
1028 // with any #[link_args] attributes found inside the crate
1029 if let Some(ref args) = sess.opts.cg.link_args {
1032 cmd.args(&used_link_args);
1035 // # Native library linking
1037 // User-supplied library search paths (-L on the command line). These are
1038 // the same paths used to find Rust crates, so some of them may have been
1039 // added already by the previous crate linking code. This only allows them
1040 // to be found at compile time so it is still entirely up to outside
1041 // forces to make sure that library can be found at runtime.
1043 // Also note that the native libraries linked here are only the ones located
1044 // in the current crate. Upstream crates with native library dependencies
1045 // may have their native library pulled in above.
1046 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1047 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1049 PathKind::Framework => { cmd.framework_path(path); }
1050 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1055 let libs = sess.cstore.get_used_libraries();
1056 let libs = libs.borrow();
1058 let staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
1059 if kind == cstore::NativeStatic {Some(l)} else {None}
1061 let others = libs.iter().filter(|&&(_, kind)| {
1062 kind != cstore::NativeStatic
1065 // Some platforms take hints about whether a library is static or dynamic.
1066 // For those that support this, we ensure we pass the option if the library
1067 // was flagged "static" (most defaults are dynamic) to ensure that if
1068 // libfoo.a and libfoo.so both exist that the right one is chosen.
1071 let search_path = archive_search_paths(sess);
1072 for l in staticlibs {
1073 // Here we explicitly ask that the entire archive is included into the
1074 // result artifact. For more details see #15460, but the gist is that
1075 // the linker will strip away any unused objects in the archive if we
1076 // don't otherwise explicitly reference them. This can occur for
1077 // libraries which are just providing bindings, libraries with generic
1079 cmd.link_whole_staticlib(l, &search_path);
1084 for &(ref l, kind) in others {
1086 cstore::NativeUnknown => cmd.link_dylib(l),
1087 cstore::NativeFramework => cmd.link_framework(l),
1088 cstore::NativeStatic => unreachable!(),
1093 // # Rust Crate linking
1095 // Rust crates are not considered at all when creating an rlib output. All
1096 // dependencies will be linked when producing the final output (instead of
1097 // the intermediate rlib version)
1098 fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
1099 dylib: bool, tmpdir: &Path,
1100 trans: &CrateTranslation) {
1101 // All of the heavy lifting has previously been accomplished by the
1102 // dependency_format module of the compiler. This is just crawling the
1103 // output of that module, adding crates as necessary.
1105 // Linking to a rlib involves just passing it to the linker (the linker
1106 // will slurp up the object files inside), and linking to a dynamic library
1107 // involves just passing the right -l flag.
1109 let data = if dylib {
1110 trans.crate_formats.get(&config::CrateTypeDylib).unwrap()
1112 trans.crate_formats.get(&config::CrateTypeExecutable).unwrap()
1115 // Invoke get_used_crates to ensure that we get a topological sorting of
1117 let deps = sess.cstore.get_used_crates(cstore::RequireDynamic);
1119 for &(cnum, _) in &deps {
1120 // We may not pass all crates through to the linker. Some crates may
1121 // appear statically in an existing dylib, meaning we'll pick up all the
1122 // symbols from the dylib.
1123 let kind = match data[cnum as usize - 1] {
1127 let src = sess.cstore.get_used_crate_source(cnum).unwrap();
1129 cstore::RequireDynamic => {
1130 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1132 cstore::RequireStatic => {
1133 add_static_crate(cmd, sess, tmpdir, dylib, &src.rlib.unwrap().0)
1139 // Converts a library file-stem into a cc -l argument
1140 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1141 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1148 // Adds the static "rlib" versions of all crates to the command line.
1149 // There's a bit of magic which happens here specifically related to LTO and
1150 // dynamic libraries. Specifically:
1152 // * For LTO, we remove upstream object files.
1153 // * For dylibs we remove metadata and bytecode from upstream rlibs
1155 // When performing LTO, all of the bytecode from the upstream libraries has
1156 // already been included in our object file output. As a result we need to
1157 // remove the object files in the upstream libraries so the linker doesn't
1158 // try to include them twice (or whine about duplicate symbols). We must
1159 // continue to include the rest of the rlib, however, as it may contain
1160 // static native libraries which must be linked in.
1162 // When making a dynamic library, linkers by default don't include any
1163 // object files in an archive if they're not necessary to resolve the link.
1164 // We basically want to convert the archive (rlib) to a dylib, though, so we
1165 // *do* want everything included in the output, regardless of whether the
1166 // linker thinks it's needed or not. As a result we must use the
1167 // --whole-archive option (or the platform equivalent). When using this
1168 // option the linker will fail if there are non-objects in the archive (such
1169 // as our own metadata and/or bytecode). All in all, for rlibs to be
1170 // entirely included in dylibs, we need to remove all non-object files.
1172 // Note, however, that if we're not doing LTO or we're not producing a dylib
1173 // (aka we're making an executable), we can just pass the rlib blindly to
1174 // the linker (fast) because it's fine if it's not actually included as
1175 // we're at the end of the dependency chain.
1176 fn add_static_crate(cmd: &mut Linker, sess: &Session, tmpdir: &Path,
1177 dylib: bool, cratepath: &Path) {
1178 if !sess.lto() && !dylib {
1179 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1183 let dst = tmpdir.join(cratepath.file_name().unwrap());
1184 let name = cratepath.file_name().unwrap().to_str().unwrap();
1185 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1187 time(sess.time_passes(), &format!("altering {}.rlib", name), (), |()| {
1189 io::copy(&mut try!(fs::File::open(&cratepath)),
1190 &mut try!(fs::File::create(&dst)))
1192 if let Err(e) = err {
1193 sess.fatal(&format!("failed to copy {} to {}: {}",
1194 cratepath.display(), dst.display(), e));
1197 let mut archive = Archive::open(archive_config(sess, &dst));
1198 archive.remove_file(METADATA_FILENAME);
1200 let mut any_objects = false;
1201 for f in archive.files() {
1202 if f.ends_with("bytecode.deflate") {
1203 archive.remove_file(&f);
1206 let canonical = f.replace("-", "_");
1207 let canonical_name = name.replace("-", "_");
1208 if sess.lto() && canonical.starts_with(&canonical_name) &&
1209 canonical.ends_with(".o") {
1210 let num = &f[name.len()..f.len() - 2];
1211 if num.len() > 0 && num[1..].parse::<u32>().is_ok() {
1212 archive.remove_file(&f);
1220 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1225 // Same thing as above, but for dynamic crates instead of static crates.
1226 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1227 // If we're performing LTO, then it should have been previously required
1228 // that all upstream rust dependencies were available in an rlib format.
1229 assert!(!sess.lto());
1231 // Just need to tell the linker about where the library lives and
1233 let parent = cratepath.parent();
1234 if let Some(dir) = parent {
1235 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1237 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1238 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1239 parent.unwrap_or(Path::new("")));
1243 // Link in all of our upstream crates' native dependencies. Remember that
1244 // all of these upstream native dependencies are all non-static
1245 // dependencies. We've got two cases then:
1247 // 1. The upstream crate is an rlib. In this case we *must* link in the
1248 // native dependency because the rlib is just an archive.
1250 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1251 // have the dependency present on the system somewhere. Thus, we don't
1252 // gain a whole lot from not linking in the dynamic dependency to this
1255 // The use case for this is a little subtle. In theory the native
1256 // dependencies of a crate are purely an implementation detail of the crate
1257 // itself, but the problem arises with generic and inlined functions. If a
1258 // generic function calls a native function, then the generic function must
1259 // be instantiated in the target crate, meaning that the native symbol must
1260 // also be resolved in the target crate.
1261 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) {
1262 // Be sure to use a topological sorting of crates because there may be
1263 // interdependencies between native libraries. When passing -nodefaultlibs,
1264 // for example, almost all native libraries depend on libc, so we have to
1265 // make sure that's all the way at the right (liblibc is near the base of
1266 // the dependency chain).
1268 // This passes RequireStatic, but the actual requirement doesn't matter,
1269 // we're just getting an ordering of crate numbers, we're not worried about
1271 let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
1272 for (cnum, _) in crates {
1273 let libs = csearch::get_native_libraries(&sess.cstore, cnum);
1274 for &(kind, ref lib) in &libs {
1276 cstore::NativeUnknown => cmd.link_dylib(lib),
1277 cstore::NativeFramework => cmd.link_framework(lib),
1278 cstore::NativeStatic => {
1279 sess.bug("statics shouldn't be propagated");