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};
14 use super::rpath::RPathConfig;
16 use super::write::{OutputTypeBitcode, OutputTypeExe, OutputTypeObject};
17 use driver::driver::{CrateTranslation, OutputFilenames, Input, FileInput};
18 use driver::config::NoDebugInfo;
19 use driver::session::Session;
21 use metadata::common::LinkMeta;
22 use metadata::{encoder, cstore, filesearch, csearch, loader, creader};
23 use middle::trans::context::CrateContext;
24 use middle::trans::common::gensym_name;
26 use util::common::time;
28 use util::sha2::{Digest, Sha256};
31 use std::collections::HashSet;
32 use std::io::{fs, TempDir, Command};
36 use std::string::String;
38 use serialize::hex::ToHex;
41 use syntax::ast_map::{PathElem, PathElems, PathName};
43 use syntax::attr::AttrMetaMethods;
44 use syntax::codemap::Span;
45 use syntax::parse::token;
47 // RLIB LLVM-BYTECODE OBJECT LAYOUT
50 // 0..10 "RUST_OBJECT" encoded in ASCII
51 // 11..14 format version as little-endian u32
52 // 15..22 size in bytes of deflate compressed LLVM bitcode as
54 // 23.. compressed LLVM bitcode
56 // This is the "magic number" expected at the beginning of a LLVM bytecode
58 pub static RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
60 // The version number this compiler will write to bytecode objects in rlibs
61 pub static RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
63 // The offset in bytes the bytecode object format version number can be found at
64 pub static RLIB_BYTECODE_OBJECT_VERSION_OFFSET: uint = 11;
66 // The offset in bytes the size of the compressed bytecode can be found at in
68 pub static RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: uint =
69 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
71 // The offset in bytes the compressed LLVM bytecode can be found at in format
73 pub static RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: uint =
74 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
78 * Name mangling and its relationship to metadata. This is complex. Read
81 * The semantic model of Rust linkage is, broadly, that "there's no global
82 * namespace" between crates. Our aim is to preserve the illusion of this
83 * model despite the fact that it's not *quite* possible to implement on
84 * modern linkers. We initially didn't use system linkers at all, but have
85 * been convinced of their utility.
87 * There are a few issues to handle:
89 * - Linkers operate on a flat namespace, so we have to flatten names.
90 * We do this using the C++ namespace-mangling technique. Foo::bar
93 * - Symbols with the same name but different types need to get different
94 * linkage-names. We do this by hashing a string-encoding of the type into
95 * a fixed-size (currently 16-byte hex) cryptographic hash function (CHF:
96 * we use SHA256) to "prevent collisions". This is not airtight but 16 hex
97 * digits on uniform probability means you're going to need 2**32 same-name
98 * symbols in the same process before you're even hitting birthday-paradox
99 * collision probability.
101 * - Symbols in different crates but with same names "within" the crate need
102 * to get different linkage-names.
104 * - The hash shown in the filename needs to be predictable and stable for
105 * build tooling integration. It also needs to be using a hash function
106 * which is easy to use from Python, make, etc.
108 * So here is what we do:
110 * - Consider the package id; every crate has one (specified with crate_id
111 * attribute). If a package id isn't provided explicitly, we infer a
112 * versionless one from the output name. The version will end up being 0.0
113 * in this case. CNAME and CVERS are taken from this package id. For
114 * example, github.com/mozilla/CNAME#CVERS.
116 * - Define CMH as SHA256(crateid).
118 * - Define CMH8 as the first 8 characters of CMH.
120 * - Compile our crate to lib CNAME-CMH8-CVERS.so
122 * - Define STH(sym) as SHA256(CMH, type_str(sym))
124 * - Suffix a mangled sym with ::STH@CVERS, so that it is unique in the
125 * name, non-name metadata, and type sense, and versioned in the way
126 * system linkers understand.
129 pub fn find_crate_name(sess: Option<&Session>,
130 attrs: &[ast::Attribute],
131 input: &Input) -> String {
132 use syntax::crateid::CrateId;
134 let validate = |s: String, span: Option<Span>| {
135 creader::validate_crate_name(sess, s.as_slice(), span);
139 // Look in attributes 100% of the time to make sure the attribute is marked
140 // as used. After doing this, however, we still prioritize a crate name from
141 // the command line over one found in the #[crate_name] attribute. If we
142 // find both we ensure that they're the same later on as well.
143 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
144 .and_then(|at| at.value_str().map(|s| (at, s)));
148 match sess.opts.crate_name {
150 match attr_crate_name {
151 Some((attr, ref name)) if s.as_slice() != name.get() => {
152 let msg = format!("--crate-name and #[crate_name] \
153 are required to match, but `{}` \
155 sess.span_err(attr.span, msg.as_slice());
159 return validate(s.clone(), None);
167 match attr_crate_name {
168 Some((attr, s)) => return validate(s.get().to_string(), Some(attr.span)),
171 let crate_id = attrs.iter().find(|at| at.check_name("crate_id"))
172 .and_then(|at| at.value_str().map(|s| (at, s)))
173 .and_then(|(at, s)| {
174 from_str::<CrateId>(s.get()).map(|id| (at, id))
177 Some((attr, id)) => {
180 sess.span_warn(attr.span, "the #[crate_id] attribute is \
182 #[crate_name] attribute");
186 return validate(id.name, Some(attr.span))
191 FileInput(ref path) => {
192 match path.filestem_str() {
193 Some(s) => return validate(s.to_string(), None),
200 "rust-out".to_string()
203 pub fn build_link_meta(sess: &Session, krate: &ast::Crate,
204 name: String) -> LinkMeta {
207 crate_hash: Svh::calculate(&sess.opts.cg.metadata, krate),
213 fn truncated_hash_result(symbol_hasher: &mut Sha256) -> String {
214 let output = symbol_hasher.result_bytes();
215 // 64 bits should be enough to avoid collisions.
216 output.slice_to(8).to_hex().to_string()
220 // This calculates STH for a symbol, as defined above
221 fn symbol_hash(tcx: &ty::ctxt,
222 symbol_hasher: &mut Sha256,
224 link_meta: &LinkMeta)
226 // NB: do *not* use abbrevs here as we want the symbol names
227 // to be independent of one another in the crate.
229 symbol_hasher.reset();
230 symbol_hasher.input_str(link_meta.crate_name.as_slice());
231 symbol_hasher.input_str("-");
232 symbol_hasher.input_str(link_meta.crate_hash.as_str());
233 for meta in tcx.sess.crate_metadata.borrow().iter() {
234 symbol_hasher.input_str(meta.as_slice());
236 symbol_hasher.input_str("-");
237 symbol_hasher.input_str(encoder::encoded_ty(tcx, t).as_slice());
238 // Prefix with 'h' so that it never blends into adjacent digits
239 let mut hash = String::from_str("h");
240 hash.push_str(truncated_hash_result(symbol_hasher).as_slice());
244 fn get_symbol_hash(ccx: &CrateContext, t: ty::t) -> String {
245 match ccx.type_hashcodes().borrow().find(&t) {
246 Some(h) => return h.to_string(),
250 let mut symbol_hasher = ccx.symbol_hasher().borrow_mut();
251 let hash = symbol_hash(ccx.tcx(), &mut *symbol_hasher, t, ccx.link_meta());
252 ccx.type_hashcodes().borrow_mut().insert(t, hash.clone());
257 // Name sanitation. LLVM will happily accept identifiers with weird names, but
259 // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $
260 pub fn sanitize(s: &str) -> String {
261 let mut result = String::new();
264 // Escape these with $ sequences
265 '@' => result.push_str("$SP$"),
266 '~' => result.push_str("$UP$"),
267 '*' => result.push_str("$RP$"),
268 '&' => result.push_str("$BP$"),
269 '<' => result.push_str("$LT$"),
270 '>' => result.push_str("$GT$"),
271 '(' => result.push_str("$LP$"),
272 ')' => result.push_str("$RP$"),
273 ',' => result.push_str("$C$"),
275 // '.' doesn't occur in types and functions, so reuse it
277 '-' | ':' => result.push_char('.'),
279 // These are legal symbols
283 | '_' | '.' | '$' => result.push_char(c),
286 let mut tstr = String::new();
287 char::escape_unicode(c, |c| tstr.push_char(c));
288 result.push_char('$');
289 result.push_str(tstr.as_slice().slice_from(1));
294 // Underscore-qualify anything that didn't start as an ident.
295 if result.len() > 0u &&
296 result.as_bytes()[0] != '_' as u8 &&
297 ! char::is_XID_start(result.as_bytes()[0] as char) {
298 return format!("_{}", result.as_slice());
304 pub fn mangle<PI: Iterator<PathElem>>(mut path: PI,
305 hash: Option<&str>) -> String {
306 // Follow C++ namespace-mangling style, see
307 // http://en.wikipedia.org/wiki/Name_mangling for more info.
309 // It turns out that on OSX you can actually have arbitrary symbols in
310 // function names (at least when given to LLVM), but this is not possible
311 // when using unix's linker. Perhaps one day when we just use a linker from LLVM
312 // we won't need to do this name mangling. The problem with name mangling is
313 // that it seriously limits the available characters. For example we can't
314 // have things like &T or ~[T] in symbol names when one would theoretically
315 // want them for things like impls of traits on that type.
317 // To be able to work on all platforms and get *some* reasonable output, we
318 // use C++ name-mangling.
320 let mut n = String::from_str("_ZN"); // _Z == Begin name-sequence, N == nested
322 fn push(n: &mut String, s: &str) {
323 let sani = sanitize(s);
324 n.push_str(format!("{}{}", sani.len(), sani).as_slice());
327 // First, connect each component with <len, name> pairs.
329 push(&mut n, token::get_name(e.name()).get().as_slice())
333 Some(s) => push(&mut n, s),
337 n.push_char('E'); // End name-sequence.
341 pub fn exported_name(path: PathElems, hash: &str) -> String {
342 mangle(path, Some(hash))
345 pub fn mangle_exported_name(ccx: &CrateContext, path: PathElems,
346 t: ty::t, id: ast::NodeId) -> String {
347 let mut hash = get_symbol_hash(ccx, t);
349 // Paths can be completely identical for different nodes,
350 // e.g. `fn foo() { { fn a() {} } { fn a() {} } }`, so we
351 // generate unique characters from the node id. For now
352 // hopefully 3 characters is enough to avoid collisions.
353 static EXTRA_CHARS: &'static str =
354 "abcdefghijklmnopqrstuvwxyz\
355 ABCDEFGHIJKLMNOPQRSTUVWXYZ\
358 let extra1 = id % EXTRA_CHARS.len();
359 let id = id / EXTRA_CHARS.len();
360 let extra2 = id % EXTRA_CHARS.len();
361 let id = id / EXTRA_CHARS.len();
362 let extra3 = id % EXTRA_CHARS.len();
363 hash.push_char(EXTRA_CHARS.as_bytes()[extra1] as char);
364 hash.push_char(EXTRA_CHARS.as_bytes()[extra2] as char);
365 hash.push_char(EXTRA_CHARS.as_bytes()[extra3] as char);
367 exported_name(path, hash.as_slice())
370 pub fn mangle_internal_name_by_type_and_seq(ccx: &CrateContext,
372 name: &str) -> String {
373 let s = ppaux::ty_to_string(ccx.tcx(), t);
374 let path = [PathName(token::intern(s.as_slice())),
376 let hash = get_symbol_hash(ccx, t);
377 mangle(ast_map::Values(path.iter()), Some(hash.as_slice()))
380 pub fn mangle_internal_name_by_path_and_seq(path: PathElems, flav: &str) -> String {
381 mangle(path.chain(Some(gensym_name(flav)).move_iter()), None)
384 pub fn get_cc_prog(sess: &Session) -> String {
385 match sess.opts.cg.linker {
386 Some(ref linker) => return linker.to_string(),
390 // In the future, FreeBSD will use clang as default compiler.
391 // It would be flexible to use cc (system's default C compiler)
392 // instead of hard-coded gcc.
393 // For Windows, there is no cc command, so we add a condition to make it use gcc.
394 match sess.targ_cfg.os {
395 abi::OsWindows => "gcc",
400 pub fn get_ar_prog(sess: &Session) -> String {
401 match sess.opts.cg.ar {
402 Some(ref ar) => (*ar).clone(),
403 None => "ar".to_string()
407 pub fn remove(sess: &Session, path: &Path) {
408 match fs::unlink(path) {
411 sess.err(format!("failed to remove {}: {}",
418 /// Perform the linkage portion of the compilation phase. This will generate all
419 /// of the requested outputs for this compilation session.
420 pub fn link_binary(sess: &Session,
421 trans: &CrateTranslation,
422 outputs: &OutputFilenames,
423 crate_name: &str) -> Vec<Path> {
424 let mut out_filenames = Vec::new();
425 for &crate_type in sess.crate_types.borrow().iter() {
426 if invalid_output_for_target(sess, crate_type) {
427 sess.bug(format!("invalid output type `{}` for target os `{}`",
428 crate_type, sess.targ_cfg.os).as_slice());
430 let out_file = link_binary_output(sess, trans, crate_type, outputs,
432 out_filenames.push(out_file);
435 // Remove the temporary object file and metadata if we aren't saving temps
436 if !sess.opts.cg.save_temps {
437 let obj_filename = outputs.temp_path(OutputTypeObject);
438 if !sess.opts.output_types.contains(&OutputTypeObject) {
439 remove(sess, &obj_filename);
441 remove(sess, &obj_filename.with_extension("metadata.o"));
448 /// Returns default crate type for target
450 /// Default crate type is used when crate type isn't provided neither
451 /// through cmd line arguments nor through crate attributes
453 /// It is CrateTypeExecutable for all platforms but iOS as there is no
454 /// way to run iOS binaries anyway without jailbreaking and
455 /// interaction with Rust code through static library is the only
457 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
458 match sess.targ_cfg.os {
459 abi::OsiOS => config::CrateTypeStaticlib,
460 _ => config::CrateTypeExecutable
464 /// Checks if target supports crate_type as output
465 pub fn invalid_output_for_target(sess: &Session,
466 crate_type: config::CrateType) -> bool {
467 match (sess.targ_cfg.os, crate_type) {
468 (abi::OsiOS, config::CrateTypeDylib) => true,
473 fn is_writeable(p: &Path) -> bool {
476 Ok(m) => m.perm & io::UserWrite == io::UserWrite
480 pub fn filename_for_input(sess: &Session,
481 crate_type: config::CrateType,
483 out_filename: &Path) -> Path {
484 let libname = format!("{}{}", name, sess.opts.cg.extra_filename);
486 config::CrateTypeRlib => {
487 out_filename.with_filename(format!("lib{}.rlib", libname))
489 config::CrateTypeDylib => {
490 let (prefix, suffix) = match sess.targ_cfg.os {
491 abi::OsWindows => (loader::WIN32_DLL_PREFIX, loader::WIN32_DLL_SUFFIX),
492 abi::OsMacos => (loader::MACOS_DLL_PREFIX, loader::MACOS_DLL_SUFFIX),
493 abi::OsLinux => (loader::LINUX_DLL_PREFIX, loader::LINUX_DLL_SUFFIX),
494 abi::OsAndroid => (loader::ANDROID_DLL_PREFIX, loader::ANDROID_DLL_SUFFIX),
495 abi::OsFreebsd => (loader::FREEBSD_DLL_PREFIX, loader::FREEBSD_DLL_SUFFIX),
496 abi::OsDragonfly => (loader::DRAGONFLY_DLL_PREFIX, loader::DRAGONFLY_DLL_SUFFIX),
497 abi::OsiOS => unreachable!(),
499 out_filename.with_filename(format!("{}{}{}",
504 config::CrateTypeStaticlib => {
505 out_filename.with_filename(format!("lib{}.a", libname))
507 config::CrateTypeExecutable => {
508 match sess.targ_cfg.os {
509 abi::OsWindows => out_filename.with_extension("exe"),
515 abi::OsiOS => out_filename.clone(),
521 fn link_binary_output(sess: &Session,
522 trans: &CrateTranslation,
523 crate_type: config::CrateType,
524 outputs: &OutputFilenames,
525 crate_name: &str) -> Path {
526 let obj_filename = outputs.temp_path(OutputTypeObject);
527 let out_filename = match outputs.single_output_file {
528 Some(ref file) => file.clone(),
530 let out_filename = outputs.path(OutputTypeExe);
531 filename_for_input(sess, crate_type, crate_name, &out_filename)
535 // Make sure the output and obj_filename are both writeable.
536 // Mac, FreeBSD, and Windows system linkers check this already --
537 // however, the Linux linker will happily overwrite a read-only file.
538 // We should be consistent.
539 let obj_is_writeable = is_writeable(&obj_filename);
540 let out_is_writeable = is_writeable(&out_filename);
541 if !out_is_writeable {
542 sess.fatal(format!("output file {} is not writeable -- check its \
544 out_filename.display()).as_slice());
546 else if !obj_is_writeable {
547 sess.fatal(format!("object file {} is not writeable -- check its \
549 obj_filename.display()).as_slice());
553 config::CrateTypeRlib => {
554 link_rlib(sess, Some(trans), &obj_filename, &out_filename).build();
556 config::CrateTypeStaticlib => {
557 link_staticlib(sess, &obj_filename, &out_filename);
559 config::CrateTypeExecutable => {
560 link_natively(sess, trans, false, &obj_filename, &out_filename);
562 config::CrateTypeDylib => {
563 link_natively(sess, trans, true, &obj_filename, &out_filename);
570 fn archive_search_paths(sess: &Session) -> Vec<Path> {
571 let mut rustpath = filesearch::rust_path();
572 rustpath.push(sess.target_filesearch().get_lib_path());
573 // FIXME: Addl lib search paths are an unordered HashSet?
574 // Shouldn't this search be done in some order?
575 let addl_lib_paths: HashSet<Path> = sess.opts.addl_lib_search_paths.borrow().clone();
576 let mut search: Vec<Path> = addl_lib_paths.move_iter().collect();
577 search.push_all(rustpath.as_slice());
583 // An rlib in its current incarnation is essentially a renamed .a file. The
584 // rlib primarily contains the object file of the crate, but it also contains
585 // all of the object files from native libraries. This is done by unzipping
586 // native libraries and inserting all of the contents into this archive.
587 fn link_rlib<'a>(sess: &'a Session,
588 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
590 out_filename: &Path) -> ArchiveBuilder<'a> {
591 let handler = &sess.diagnostic().handler;
592 let config = ArchiveConfig {
594 dst: out_filename.clone(),
595 lib_search_paths: archive_search_paths(sess),
596 os: sess.targ_cfg.os,
597 maybe_ar_prog: sess.opts.cg.ar.clone()
599 let mut ab = ArchiveBuilder::create(config);
600 ab.add_file(obj_filename).unwrap();
602 for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() {
604 cstore::NativeStatic => {
605 ab.add_native_library(l.as_slice()).unwrap();
607 cstore::NativeFramework | cstore::NativeUnknown => {}
611 // After adding all files to the archive, we need to update the
612 // symbol table of the archive.
615 let mut ab = match sess.targ_cfg.os {
616 // For OSX/iOS, we must be careful to update symbols only when adding
617 // object files. We're about to start adding non-object files, so run
618 // `ar` now to process the object files.
619 abi::OsMacos | abi::OsiOS => ab.build().extend(),
623 // Note that it is important that we add all of our non-object "magical
624 // files" *after* all of the object files in the archive. The reason for
625 // this is as follows:
627 // * When performing LTO, this archive will be modified to remove
628 // obj_filename from above. The reason for this is described below.
630 // * When the system linker looks at an archive, it will attempt to
631 // determine the architecture of the archive in order to see whether its
634 // The algorithm for this detection is: iterate over the files in the
635 // archive. Skip magical SYMDEF names. Interpret the first file as an
636 // object file. Read architecture from the object file.
638 // * As one can probably see, if "metadata" and "foo.bc" were placed
639 // before all of the objects, then the architecture of this archive would
640 // not be correctly inferred once 'foo.o' is removed.
642 // Basically, all this means is that this code should not move above the
646 // Instead of putting the metadata in an object file section, rlibs
647 // contain the metadata in a separate file. We use a temp directory
648 // here so concurrent builds in the same directory don't try to use
649 // the same filename for metadata (stomping over one another)
650 let tmpdir = TempDir::new("rustc").ok().expect("needs a temp dir");
651 let metadata = tmpdir.path().join(METADATA_FILENAME);
652 match fs::File::create(&metadata).write(trans.metadata
656 sess.err(format!("failed to write {}: {}",
659 sess.abort_if_errors();
662 ab.add_file(&metadata).unwrap();
663 remove(sess, &metadata);
665 if sess.opts.cg.codegen_units == 1 {
666 // For LTO purposes, the bytecode of this library is also
667 // inserted into the archive. We currently do this only when
668 // codegen_units == 1, so we don't have to deal with multiple
669 // bitcode files per crate.
671 // Note that we make sure that the bytecode filename in the
672 // archive is never exactly 16 bytes long by adding a 16 byte
673 // extension to it. This is to work around a bug in LLDB that
674 // would cause it to crash if the name of a file in an archive
675 // was exactly 16 bytes.
676 let bc_filename = obj_filename.with_extension("bc");
677 let bc_deflated_filename = obj_filename.with_extension("bytecode.deflate");
679 let bc_data = match fs::File::open(&bc_filename).read_to_end() {
680 Ok(buffer) => buffer,
681 Err(e) => sess.fatal(format!("failed to read bytecode: {}",
685 let bc_data_deflated = match flate::deflate_bytes(bc_data.as_slice()) {
686 Some(compressed) => compressed,
687 None => sess.fatal(format!("failed to compress bytecode from {}",
688 bc_filename.display()).as_slice())
691 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
694 sess.fatal(format!("failed to create compressed bytecode \
695 file: {}", e).as_slice())
699 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
700 bc_data_deflated.as_slice()) {
703 sess.err(format!("failed to write compressed bytecode: \
705 sess.abort_if_errors()
709 ab.add_file(&bc_deflated_filename).unwrap();
710 remove(sess, &bc_deflated_filename);
711 if !sess.opts.cg.save_temps &&
712 !sess.opts.output_types.contains(&OutputTypeBitcode) {
713 remove(sess, &bc_filename);
724 fn write_rlib_bytecode_object_v1<T: Writer>(writer: &mut T,
725 bc_data_deflated: &[u8])
726 -> ::std::io::IoResult<()> {
727 let bc_data_deflated_size: u64 = bc_data_deflated.as_slice().len() as u64;
729 try! { writer.write(RLIB_BYTECODE_OBJECT_MAGIC) };
730 try! { writer.write_le_u32(1) };
731 try! { writer.write_le_u64(bc_data_deflated_size) };
732 try! { writer.write(bc_data_deflated.as_slice()) };
734 let number_of_bytes_written_so_far =
735 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
736 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
737 mem::size_of_val(&bc_data_deflated_size) + // data size field
738 bc_data_deflated_size as uint; // actual data
740 // If the number of bytes written to the object so far is odd, add a
741 // padding byte to make it even. This works around a crash bug in LLDB
742 // (see issue #15950)
743 if number_of_bytes_written_so_far % 2 == 1 {
744 try! { writer.write_u8(0) };
750 // Create a static archive
752 // This is essentially the same thing as an rlib, but it also involves adding
753 // all of the upstream crates' objects into the archive. This will slurp in
754 // all of the native libraries of upstream dependencies as well.
756 // Additionally, there's no way for us to link dynamic libraries, so we warn
757 // about all dynamic library dependencies that they're not linked in.
759 // There's no need to include metadata in a static archive, so ensure to not
760 // link in the metadata object file (and also don't prepare the archive with a
762 fn link_staticlib(sess: &Session, obj_filename: &Path, out_filename: &Path) {
763 let ab = link_rlib(sess, None, obj_filename, out_filename);
764 let mut ab = match sess.targ_cfg.os {
765 abi::OsMacos | abi::OsiOS => ab.build().extend(),
768 ab.add_native_library("morestack").unwrap();
769 ab.add_native_library("compiler-rt").unwrap();
771 let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
772 let mut all_native_libs = vec![];
774 for &(cnum, ref path) in crates.iter() {
775 let name = sess.cstore.get_crate_data(cnum).name.clone();
776 let p = match *path {
777 Some(ref p) => p.clone(), None => {
778 sess.err(format!("could not find rlib for: `{}`",
783 ab.add_rlib(&p, name.as_slice(), sess.lto()).unwrap();
785 let native_libs = csearch::get_native_libraries(&sess.cstore, cnum);
786 all_native_libs.extend(native_libs.move_iter());
792 if !all_native_libs.is_empty() {
793 sess.warn("link against the following native artifacts when linking against \
794 this static library");
795 sess.note("the order and any duplication can be significant on some platforms, \
796 and so may need to be preserved");
799 for &(kind, ref lib) in all_native_libs.iter() {
800 let name = match kind {
801 cstore::NativeStatic => "static library",
802 cstore::NativeUnknown => "library",
803 cstore::NativeFramework => "framework",
805 sess.note(format!("{}: {}", name, *lib).as_slice());
809 // Create a dynamic library or executable
811 // This will invoke the system linker/cc to create the resulting file. This
812 // links to all upstream files as well.
813 fn link_natively(sess: &Session, trans: &CrateTranslation, dylib: bool,
814 obj_filename: &Path, out_filename: &Path) {
815 let tmpdir = TempDir::new("rustc").ok().expect("needs a temp dir");
817 // The invocations of cc share some flags across platforms
818 let pname = get_cc_prog(sess);
819 let mut cmd = Command::new(pname.as_slice());
821 cmd.args(sess.targ_cfg.target_strs.cc_args.as_slice());
822 link_args(&mut cmd, sess, dylib, tmpdir.path(),
823 trans, obj_filename, out_filename);
825 if (sess.opts.debugging_opts & config::PRINT_LINK_ARGS) != 0 {
826 println!("{}", &cmd);
829 // May have not found libraries in the right formats.
830 sess.abort_if_errors();
832 // Invoke the system linker
834 let prog = time(sess.time_passes(), "running linker", (), |()| cmd.output());
837 if !prog.status.success() {
838 sess.err(format!("linking with `{}` failed: {}",
840 prog.status).as_slice());
841 sess.note(format!("{}", &cmd).as_slice());
842 let mut output = prog.error.clone();
843 output.push_all(prog.output.as_slice());
844 sess.note(str::from_utf8(output.as_slice()).unwrap());
845 sess.abort_if_errors();
847 debug!("linker stderr:\n{}", str::from_utf8_owned(prog.error).unwrap());
848 debug!("linker stdout:\n{}", str::from_utf8_owned(prog.output).unwrap());
851 sess.err(format!("could not exec the linker `{}`: {}",
854 sess.abort_if_errors();
859 // On OSX, debuggers need this utility to get run to do some munging of
861 if (sess.targ_cfg.os == abi::OsMacos || sess.targ_cfg.os == abi::OsiOS)
862 && (sess.opts.debuginfo != NoDebugInfo) {
863 match Command::new("dsymutil").arg(out_filename).output() {
866 sess.err(format!("failed to run dsymutil: {}", e).as_slice());
867 sess.abort_if_errors();
873 fn link_args(cmd: &mut Command,
877 trans: &CrateTranslation,
879 out_filename: &Path) {
881 // The default library location, we need this to find the runtime.
882 // The location of crates will be determined as needed.
883 let lib_path = sess.target_filesearch().get_lib_path();
884 cmd.arg("-L").arg(&lib_path);
886 cmd.arg("-o").arg(out_filename).arg(obj_filename);
888 // Stack growth requires statically linking a __morestack function. Note
889 // that this is listed *before* all other libraries. Due to the usage of the
890 // --as-needed flag below, the standard library may only be useful for its
891 // rust_stack_exhausted function. In this case, we must ensure that the
892 // libmorestack.a file appears *before* the standard library (so we put it
893 // at the very front).
895 // Most of the time this is sufficient, except for when LLVM gets super
896 // clever. If, for example, we have a main function `fn main() {}`, LLVM
897 // will optimize out calls to `__morestack` entirely because the function
898 // doesn't need any stack at all!
900 // To get around this snag, we specially tell the linker to always include
901 // all contents of this library. This way we're guaranteed that the linker
902 // will include the __morestack symbol 100% of the time, always resolving
903 // references to it even if the object above didn't use it.
904 match sess.targ_cfg.os {
905 abi::OsMacos | abi::OsiOS => {
906 let morestack = lib_path.join("libmorestack.a");
908 let mut v = b"-Wl,-force_load,".to_vec();
909 v.push_all(morestack.as_vec());
910 cmd.arg(v.as_slice());
913 cmd.args(["-Wl,--whole-archive", "-lmorestack",
914 "-Wl,--no-whole-archive"]);
918 // When linking a dynamic library, we put the metadata into a section of the
919 // executable. This metadata is in a separate object file from the main
920 // object file, so we link that in here.
922 cmd.arg(obj_filename.with_extension("metadata.o"));
925 // We want to prevent the compiler from accidentally leaking in any system
926 // libraries, so we explicitly ask gcc to not link to any libraries by
927 // default. Note that this does not happen for windows because windows pulls
928 // in some large number of libraries and I couldn't quite figure out which
931 // FIXME(#11937) we should invoke the system linker directly
932 if sess.targ_cfg.os != abi::OsWindows {
933 cmd.arg("-nodefaultlibs");
936 // If we're building a dylib, we don't use --gc-sections because LLVM has
937 // already done the best it can do, and we also don't want to eliminate the
938 // metadata. If we're building an executable, however, --gc-sections drops
939 // the size of hello world from 1.8MB to 597K, a 67% reduction.
940 if !dylib && sess.targ_cfg.os != abi::OsMacos && sess.targ_cfg.os != abi::OsiOS {
941 cmd.arg("-Wl,--gc-sections");
944 let used_link_args = sess.cstore.get_used_link_args().borrow();
946 // Dynamically linked executables can be compiled as position independent if the default
947 // relocation model of position independent code is not changed. This is a requirement to take
948 // advantage of ASLR, as otherwise the functions in the executable are not randomized and can
949 // be used during an exploit of a vulnerability in any code.
950 if sess.targ_cfg.os == abi::OsLinux {
951 let mut args = sess.opts.cg.link_args.iter().chain(used_link_args.iter());
952 if !dylib && sess.opts.cg.relocation_model.as_slice() == "pic" &&
953 !args.any(|x| x.as_slice() == "-static") {
958 if sess.targ_cfg.os == abi::OsLinux || sess.targ_cfg.os == abi::OsDragonfly {
959 // GNU-style linkers will use this to omit linking to libraries which
960 // don't actually fulfill any relocations, but only for libraries which
961 // follow this flag. Thus, use it before specifying libraries to link to.
962 cmd.arg("-Wl,--as-needed");
964 // GNU-style linkers support optimization with -O. GNU ld doesn't need a
965 // numeric argument, but other linkers do.
966 if sess.opts.optimize == config::Default ||
967 sess.opts.optimize == config::Aggressive {
970 } else if sess.targ_cfg.os == abi::OsMacos || sess.targ_cfg.os == abi::OsiOS {
971 // The dead_strip option to the linker specifies that functions and data
972 // unreachable by the entry point will be removed. This is quite useful
973 // with Rust's compilation model of compiling libraries at a time into
974 // one object file. For example, this brings hello world from 1.7MB to
977 // Note that this is done for both executables and dynamic libraries. We
978 // won't get much benefit from dylibs because LLVM will have already
979 // stripped away as much as it could. This has not been seen to impact
980 // link times negatively.
981 cmd.arg("-Wl,-dead_strip");
984 if sess.targ_cfg.os == abi::OsWindows {
985 // Make sure that we link to the dynamic libgcc, otherwise cross-module
986 // DWARF stack unwinding will not work.
987 // This behavior may be overridden by --link-args "-static-libgcc"
988 cmd.arg("-shared-libgcc");
990 // And here, we see obscure linker flags #45. On windows, it has been
991 // found to be necessary to have this flag to compile liblibc.
993 // First a bit of background. On Windows, the file format is not ELF,
994 // but COFF (at least according to LLVM). COFF doesn't officially allow
995 // for section names over 8 characters, apparently. Our metadata
996 // section, ".note.rustc", you'll note is over 8 characters.
998 // On more recent versions of gcc on mingw, apparently the section name
999 // is *not* truncated, but rather stored elsewhere in a separate lookup
1000 // table. On older versions of gcc, they apparently always truncated the
1001 // section names (at least in some cases). Truncating the section name
1002 // actually creates "invalid" objects [1] [2], but only for some
1003 // introspection tools, not in terms of whether it can be loaded.
1005 // Long story short, passing this flag forces the linker to *not*
1006 // truncate section names (so we can find the metadata section after
1007 // it's compiled). The real kicker is that rust compiled just fine on
1008 // windows for quite a long time *without* this flag, so I have no idea
1009 // why it suddenly started failing for liblibc. Regardless, we
1010 // definitely don't want section name truncation, so we're keeping this
1011 // flag for windows.
1013 // [1] - https://sourceware.org/bugzilla/show_bug.cgi?id=13130
1014 // [2] - https://code.google.com/p/go/issues/detail?id=2139
1015 cmd.arg("-Wl,--enable-long-section-names");
1017 // Always enable DEP (NX bit) when it is available
1018 cmd.arg("-Wl,--nxcompat");
1020 // Mark all dynamic libraries and executables as compatible with ASLR
1021 cmd.arg("-Wl,--dynamicbase");
1024 if sess.targ_cfg.os == abi::OsAndroid {
1025 // Many of the symbols defined in compiler-rt are also defined in libgcc.
1026 // Android linker doesn't like that by default.
1027 cmd.arg("-Wl,--allow-multiple-definition");
1030 // Take careful note of the ordering of the arguments we pass to the linker
1031 // here. Linkers will assume that things on the left depend on things to the
1032 // right. Things on the right cannot depend on things on the left. This is
1033 // all formally implemented in terms of resolving symbols (libs on the right
1034 // resolve unknown symbols of libs on the left, but not vice versa).
1036 // For this reason, we have organized the arguments we pass to the linker as
1039 // 1. The local object that LLVM just generated
1040 // 2. Upstream rust libraries
1041 // 3. Local native libraries
1042 // 4. Upstream native libraries
1044 // This is generally fairly natural, but some may expect 2 and 3 to be
1045 // swapped. The reason that all native libraries are put last is that it's
1046 // not recommended for a native library to depend on a symbol from a rust
1047 // crate. If this is the case then a staticlib crate is recommended, solving
1050 // Additionally, it is occasionally the case that upstream rust libraries
1051 // depend on a local native library. In the case of libraries such as
1052 // lua/glfw/etc the name of the library isn't the same across all platforms,
1053 // so only the consumer crate of a library knows the actual name. This means
1054 // that downstream crates will provide the #[link] attribute which upstream
1055 // crates will depend on. Hence local native libraries are after out
1056 // upstream rust crates.
1058 // In theory this means that a symbol in an upstream native library will be
1059 // shadowed by a local native library when it wouldn't have been before, but
1060 // this kind of behavior is pretty platform specific and generally not
1061 // recommended anyway, so I don't think we're shooting ourself in the foot
1063 add_upstream_rust_crates(cmd, sess, dylib, tmpdir, trans);
1064 add_local_native_libraries(cmd, sess);
1065 add_upstream_native_libraries(cmd, sess);
1067 // # Telling the linker what we're doing
1070 // On mac we need to tell the linker to let this library be rpathed
1071 if sess.targ_cfg.os == abi::OsMacos {
1072 cmd.args(["-dynamiclib", "-Wl,-dylib"]);
1074 if sess.opts.cg.rpath {
1075 let mut v = Vec::from_slice("-Wl,-install_name,@rpath/".as_bytes());
1076 v.push_all(out_filename.filename().unwrap());
1077 cmd.arg(v.as_slice());
1084 if sess.targ_cfg.os == abi::OsFreebsd {
1085 cmd.args(["-L/usr/local/lib",
1086 "-L/usr/local/lib/gcc46",
1087 "-L/usr/local/lib/gcc44"]);
1089 else if sess.targ_cfg.os == abi::OsDragonfly {
1090 cmd.args(["-L/usr/local/lib",
1092 "-L/usr/lib/gcc44"]);
1096 // FIXME (#2397): At some point we want to rpath our guesses as to
1097 // where extern libraries might live, based on the
1098 // addl_lib_search_paths
1099 if sess.opts.cg.rpath {
1100 let sysroot = sess.sysroot();
1101 let target_triple = sess.opts.target_triple.as_slice();
1102 let get_install_prefix_lib_path = || {
1103 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1104 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1105 let mut path = Path::new(install_prefix);
1110 let rpath_config = RPathConfig {
1111 os: sess.targ_cfg.os,
1112 used_crates: sess.cstore.get_used_crates(cstore::RequireDynamic),
1113 out_filename: out_filename.clone(),
1114 get_install_prefix_lib_path: get_install_prefix_lib_path,
1115 realpath: ::util::fs::realpath
1117 cmd.args(rpath::get_rpath_flags(rpath_config).as_slice());
1120 // compiler-rt contains implementations of low-level LLVM helpers. This is
1121 // used to resolve symbols from the object file we just created, as well as
1122 // any system static libraries that may be expecting gcc instead. Most
1123 // symbols in libgcc also appear in compiler-rt.
1125 // This is the end of the command line, so this library is used to resolve
1126 // *all* undefined symbols in all other libraries, and this is intentional.
1127 cmd.arg("-lcompiler-rt");
1129 // Finally add all the linker arguments provided on the command line along
1130 // with any #[link_args] attributes found inside the crate
1131 cmd.args(sess.opts.cg.link_args.as_slice());
1132 cmd.args(used_link_args.as_slice());
1135 // # Native library linking
1137 // User-supplied library search paths (-L on the command line). These are
1138 // the same paths used to find Rust crates, so some of them may have been
1139 // added already by the previous crate linking code. This only allows them
1140 // to be found at compile time so it is still entirely up to outside
1141 // forces to make sure that library can be found at runtime.
1143 // Also note that the native libraries linked here are only the ones located
1144 // in the current crate. Upstream crates with native library dependencies
1145 // may have their native library pulled in above.
1146 fn add_local_native_libraries(cmd: &mut Command, sess: &Session) {
1147 for path in sess.opts.addl_lib_search_paths.borrow().iter() {
1148 cmd.arg("-L").arg(path);
1151 let rustpath = filesearch::rust_path();
1152 for path in rustpath.iter() {
1153 cmd.arg("-L").arg(path);
1156 // Some platforms take hints about whether a library is static or dynamic.
1157 // For those that support this, we ensure we pass the option if the library
1158 // was flagged "static" (most defaults are dynamic) to ensure that if
1159 // libfoo.a and libfoo.so both exist that the right one is chosen.
1160 let takes_hints = sess.targ_cfg.os != abi::OsMacos &&
1161 sess.targ_cfg.os != abi::OsiOS;
1163 let libs = sess.cstore.get_used_libraries();
1164 let libs = libs.borrow();
1166 let mut staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
1167 if kind == cstore::NativeStatic {Some(l)} else {None}
1169 let mut others = libs.iter().filter(|&&(_, kind)| {
1170 kind != cstore::NativeStatic
1173 // Platforms that take hints generally also support the --whole-archive
1174 // flag. We need to pass this flag when linking static native libraries to
1175 // ensure the entire library is included.
1177 // For more details see #15460, but the gist is that the linker will strip
1178 // away any unused objects in the archive if we don't otherwise explicitly
1179 // reference them. This can occur for libraries which are just providing
1180 // bindings, libraries with generic functions, etc.
1182 cmd.arg("-Wl,--whole-archive").arg("-Wl,-Bstatic");
1184 let search_path = archive_search_paths(sess);
1185 for l in staticlibs {
1187 cmd.arg(format!("-l{}", l));
1189 // -force_load is the OSX equivalent of --whole-archive, but it
1190 // involves passing the full path to the library to link.
1191 let lib = archive::find_library(l.as_slice(),
1193 search_path.as_slice(),
1194 &sess.diagnostic().handler);
1195 let mut v = b"-Wl,-force_load,".to_vec();
1196 v.push_all(lib.as_vec());
1197 cmd.arg(v.as_slice());
1201 cmd.arg("-Wl,--no-whole-archive").arg("-Wl,-Bdynamic");
1204 for &(ref l, kind) in others {
1206 cstore::NativeUnknown => {
1207 cmd.arg(format!("-l{}", l));
1209 cstore::NativeFramework => {
1210 cmd.arg("-framework").arg(l.as_slice());
1212 cstore::NativeStatic => unreachable!(),
1217 // # Rust Crate linking
1219 // Rust crates are not considered at all when creating an rlib output. All
1220 // dependencies will be linked when producing the final output (instead of
1221 // the intermediate rlib version)
1222 fn add_upstream_rust_crates(cmd: &mut Command, sess: &Session,
1223 dylib: bool, tmpdir: &Path,
1224 trans: &CrateTranslation) {
1225 // All of the heavy lifting has previously been accomplished by the
1226 // dependency_format module of the compiler. This is just crawling the
1227 // output of that module, adding crates as necessary.
1229 // Linking to a rlib involves just passing it to the linker (the linker
1230 // will slurp up the object files inside), and linking to a dynamic library
1231 // involves just passing the right -l flag.
1233 let data = if dylib {
1234 trans.crate_formats.get(&config::CrateTypeDylib)
1236 trans.crate_formats.get(&config::CrateTypeExecutable)
1239 // Invoke get_used_crates to ensure that we get a topological sorting of
1241 let deps = sess.cstore.get_used_crates(cstore::RequireDynamic);
1243 for &(cnum, _) in deps.iter() {
1244 // We may not pass all crates through to the linker. Some crates may
1245 // appear statically in an existing dylib, meaning we'll pick up all the
1246 // symbols from the dylib.
1247 let kind = match *data.get(cnum as uint - 1) {
1251 let src = sess.cstore.get_used_crate_source(cnum).unwrap();
1253 cstore::RequireDynamic => {
1254 add_dynamic_crate(cmd, sess, src.dylib.unwrap())
1256 cstore::RequireStatic => {
1257 add_static_crate(cmd, sess, tmpdir, src.rlib.unwrap())
1263 // Converts a library file-stem into a cc -l argument
1264 fn unlib<'a>(config: &config::Config, stem: &'a [u8]) -> &'a [u8] {
1265 if stem.starts_with("lib".as_bytes()) && config.os != abi::OsWindows {
1272 // Adds the static "rlib" versions of all crates to the command line.
1273 fn add_static_crate(cmd: &mut Command, sess: &Session, tmpdir: &Path,
1275 // When performing LTO on an executable output, all of the
1276 // bytecode from the upstream libraries has already been
1277 // included in our object file output. We need to modify all of
1278 // the upstream archives to remove their corresponding object
1279 // file to make sure we don't pull the same code in twice.
1281 // We must continue to link to the upstream archives to be sure
1282 // to pull in native static dependencies. As the final caveat,
1283 // on Linux it is apparently illegal to link to a blank archive,
1284 // so if an archive no longer has any object files in it after
1285 // we remove `lib.o`, then don't link against it at all.
1287 // If we're not doing LTO, then our job is simply to just link
1288 // against the archive.
1290 let name = cratepath.filename_str().unwrap();
1291 let name = name.slice(3, name.len() - 5); // chop off lib/.rlib
1292 time(sess.time_passes(),
1293 format!("altering {}.rlib", name).as_slice(),
1295 let dst = tmpdir.join(cratepath.filename().unwrap());
1296 match fs::copy(&cratepath, &dst) {
1299 sess.err(format!("failed to copy {} to {}: {}",
1300 cratepath.display(),
1303 sess.abort_if_errors();
1306 let handler = &sess.diagnostic().handler;
1307 let config = ArchiveConfig {
1310 lib_search_paths: archive_search_paths(sess),
1311 os: sess.targ_cfg.os,
1312 maybe_ar_prog: sess.opts.cg.ar.clone()
1314 let mut archive = Archive::open(config);
1315 archive.remove_file(format!("{}.o", name).as_slice());
1316 let files = archive.files();
1317 if files.iter().any(|s| s.as_slice().ends_with(".o")) {
1326 // Same thing as above, but for dynamic crates instead of static crates.
1327 fn add_dynamic_crate(cmd: &mut Command, sess: &Session, cratepath: Path) {
1328 // If we're performing LTO, then it should have been previously required
1329 // that all upstream rust dependencies were available in an rlib format.
1330 assert!(!sess.lto());
1332 // Just need to tell the linker about where the library lives and
1334 let dir = cratepath.dirname();
1335 if !dir.is_empty() { cmd.arg("-L").arg(dir); }
1337 let mut v = Vec::from_slice("-l".as_bytes());
1338 v.push_all(unlib(&sess.targ_cfg, cratepath.filestem().unwrap()));
1339 cmd.arg(v.as_slice());
1343 // Link in all of our upstream crates' native dependencies. Remember that
1344 // all of these upstream native dependencies are all non-static
1345 // dependencies. We've got two cases then:
1347 // 1. The upstream crate is an rlib. In this case we *must* link in the
1348 // native dependency because the rlib is just an archive.
1350 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1351 // have the dependency present on the system somewhere. Thus, we don't
1352 // gain a whole lot from not linking in the dynamic dependency to this
1355 // The use case for this is a little subtle. In theory the native
1356 // dependencies of a crate are purely an implementation detail of the crate
1357 // itself, but the problem arises with generic and inlined functions. If a
1358 // generic function calls a native function, then the generic function must
1359 // be instantiated in the target crate, meaning that the native symbol must
1360 // also be resolved in the target crate.
1361 fn add_upstream_native_libraries(cmd: &mut Command, sess: &Session) {
1362 // Be sure to use a topological sorting of crates because there may be
1363 // interdependencies between native libraries. When passing -nodefaultlibs,
1364 // for example, almost all native libraries depend on libc, so we have to
1365 // make sure that's all the way at the right (liblibc is near the base of
1366 // the dependency chain).
1368 // This passes RequireStatic, but the actual requirement doesn't matter,
1369 // we're just getting an ordering of crate numbers, we're not worried about
1371 let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
1372 for (cnum, _) in crates.move_iter() {
1373 let libs = csearch::get_native_libraries(&sess.cstore, cnum);
1374 for &(kind, ref lib) in libs.iter() {
1376 cstore::NativeUnknown => {
1377 cmd.arg(format!("-l{}", *lib));
1379 cstore::NativeFramework => {
1380 cmd.arg("-framework");
1381 cmd.arg(lib.as_slice());
1383 cstore::NativeStatic => {
1384 sess.bug("statics shouldn't be propagated");