1 //! Finds crate binaries and loads their metadata
3 //! Might I be the first to welcome you to a world of platform differences,
4 //! version requirements, dependency graphs, conflicting desires, and fun! This
5 //! is the major guts (along with metadata::creader) of the compiler for loading
6 //! crates and resolving dependencies. Let's take a tour!
10 //! Each invocation of the compiler is immediately concerned with one primary
11 //! problem, to connect a set of crates to resolved crates on the filesystem.
12 //! Concretely speaking, the compiler follows roughly these steps to get here:
14 //! 1. Discover a set of `extern crate` statements.
15 //! 2. Transform these directives into crate names. If the directive does not
16 //! have an explicit name, then the identifier is the name.
17 //! 3. For each of these crate names, find a corresponding crate on the
20 //! Sounds easy, right? Let's walk into some of the nuances.
22 //! ## Transitive Dependencies
24 //! Let's say we've got three crates: A, B, and C. A depends on B, and B depends
25 //! on C. When we're compiling A, we primarily need to find and locate B, but we
26 //! also end up needing to find and locate C as well.
28 //! The reason for this is that any of B's types could be composed of C's types,
29 //! any function in B could return a type from C, etc. To be able to guarantee
30 //! that we can always type-check/translate any function, we have to have
31 //! complete knowledge of the whole ecosystem, not just our immediate
34 //! So now as part of the "find a corresponding crate on the filesystem" step
35 //! above, this involves also finding all crates for *all upstream
36 //! dependencies*. This includes all dependencies transitively.
38 //! ## Rlibs and Dylibs
40 //! The compiler has two forms of intermediate dependencies. These are dubbed
41 //! rlibs and dylibs for the static and dynamic variants, respectively. An rlib
42 //! is a rustc-defined file format (currently just an ar archive) while a dylib
43 //! is a platform-defined dynamic library. Each library has a metadata somewhere
46 //! A third kind of dependency is an rmeta file. These are metadata files and do
47 //! not contain any code, etc. To a first approximation, these are treated in the
48 //! same way as rlibs. Where there is both an rlib and an rmeta file, the rlib
49 //! gets priority (even if the rmeta file is newer). An rmeta file is only
50 //! useful for checking a downstream crate, attempting to link one will cause an
53 //! When translating a crate name to a crate on the filesystem, we all of a
54 //! sudden need to take into account both rlibs and dylibs! Linkage later on may
55 //! use either one of these files, as each has their pros/cons. The job of crate
56 //! loading is to discover what's possible by finding all candidates.
58 //! Most parts of this loading systems keep the dylib/rlib as just separate
63 //! We can't exactly scan your whole hard drive when looking for dependencies,
64 //! so we need to places to look. Currently the compiler will implicitly add the
65 //! target lib search path ($prefix/lib/rustlib/$target/lib) to any compilation,
66 //! and otherwise all -L flags are added to the search paths.
68 //! ## What criterion to select on?
70 //! This a pretty tricky area of loading crates. Given a file, how do we know
71 //! whether it's the right crate? Currently, the rules look along these lines:
73 //! 1. Does the filename match an rlib/dylib pattern? That is to say, does the
74 //! filename have the right prefix/suffix?
75 //! 2. Does the filename have the right prefix for the crate name being queried?
76 //! This is filtering for files like `libfoo*.rlib` and such. If the crate
77 //! we're looking for was originally compiled with -C extra-filename, the
78 //! extra filename will be included in this prefix to reduce reading
79 //! metadata from crates that would otherwise share our prefix.
80 //! 3. Is the file an actual rust library? This is done by loading the metadata
81 //! from the library and making sure it's actually there.
82 //! 4. Does the name in the metadata agree with the name of the library?
83 //! 5. Does the target in the metadata agree with the current target?
84 //! 6. Does the SVH match? (more on this later)
86 //! If the file answers `yes` to all these questions, then the file is
87 //! considered as being *candidate* for being accepted. It is illegal to have
88 //! more than two candidates as the compiler has no method by which to resolve
89 //! this conflict. Additionally, rlib/dylib candidates are considered
92 //! After all this has happened, we have 1 or two files as candidates. These
93 //! represent the rlib/dylib file found for a library, and they're returned as
96 //! ### What about versions?
98 //! A lot of effort has been put forth to remove versioning from the compiler.
99 //! There have been forays in the past to have versioning baked in, but it was
100 //! largely always deemed insufficient to the point that it was recognized that
101 //! it's probably something the compiler shouldn't do anyway due to its
102 //! complicated nature and the state of the half-baked solutions.
104 //! With a departure from versioning, the primary criterion for loading crates
105 //! is just the name of a crate. If we stopped here, it would imply that you
106 //! could never link two crates of the same name from different sources
107 //! together, which is clearly a bad state to be in.
109 //! To resolve this problem, we come to the next section!
113 //! A number of flags have been added to the compiler to solve the "version
114 //! problem" in the previous section, as well as generally enabling more
115 //! powerful usage of the crate loading system of the compiler. The goal of
116 //! these flags and options are to enable third-party tools to drive the
117 //! compiler with prior knowledge about how the world should look.
119 //! ## The `--extern` flag
121 //! The compiler accepts a flag of this form a number of times:
124 //! --extern crate-name=path/to/the/crate.rlib
127 //! This flag is basically the following letter to the compiler:
131 //! > When you are attempting to load the immediate dependency `crate-name`, I
132 //! > would like you to assume that the library is located at
133 //! > `path/to/the/crate.rlib`, and look nowhere else. Also, please do not
134 //! > assume that the path I specified has the name `crate-name`.
136 //! This flag basically overrides most matching logic except for validating that
137 //! the file is indeed a rust library. The same `crate-name` can be specified
138 //! twice to specify the rlib/dylib pair.
140 //! ## Enabling "multiple versions"
142 //! This basically boils down to the ability to specify arbitrary packages to
143 //! the compiler. For example, if crate A wanted to use Bv1 and Bv2, then it
144 //! would look something like:
146 //! ```compile_fail,E0463
153 //! and the compiler would be invoked as:
156 //! rustc a.rs --extern b1=path/to/libb1.rlib --extern b2=path/to/libb2.rlib
159 //! In this scenario there are two crates named `b` and the compiler must be
160 //! manually driven to be informed where each crate is.
162 //! ## Frobbing symbols
164 //! One of the immediate problems with linking the same library together twice
165 //! in the same problem is dealing with duplicate symbols. The primary way to
166 //! deal with this in rustc is to add hashes to the end of each symbol.
168 //! In order to force hashes to change between versions of a library, if
169 //! desired, the compiler exposes an option `-C metadata=foo`, which is used to
170 //! initially seed each symbol hash. The string `foo` is prepended to each
171 //! string-to-hash to ensure that symbols change over time.
173 //! ## Loading transitive dependencies
175 //! Dealing with same-named-but-distinct crates is not just a local problem, but
176 //! one that also needs to be dealt with for transitive dependencies. Note that
177 //! in the letter above `--extern` flags only apply to the *local* set of
178 //! dependencies, not the upstream transitive dependencies. Consider this
179 //! dependency graph:
191 //! In this scenario, when we compile `D`, we need to be able to distinctly
192 //! resolve `A.1` and `A.2`, but an `--extern` flag cannot apply to these
193 //! transitive dependencies.
195 //! Note that the key idea here is that `B` and `C` are both *already compiled*.
196 //! That is, they have already resolved their dependencies. Due to unrelated
197 //! technical reasons, when a library is compiled, it is only compatible with
198 //! the *exact same* version of the upstream libraries it was compiled against.
199 //! We use the "Strict Version Hash" to identify the exact copy of an upstream
202 //! With this knowledge, we know that `B` and `C` will depend on `A` with
203 //! different SVH values, so we crawl the normal `-L` paths looking for
204 //! `liba*.rlib` and filter based on the contained SVH.
206 //! In the end, this ends up not needing `--extern` to specify upstream
207 //! transitive dependencies.
211 //! That's the general overview of loading crates in the compiler, but it's by
212 //! no means all of the necessary details. Take a look at the rest of
213 //! metadata::locator or metadata::creader for all the juicy details!
215 use crate::creader::Library;
216 use crate::rmeta::{rustc_version, MetadataBlob, METADATA_HEADER};
218 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
219 use rustc_data_structures::svh::Svh;
220 use rustc_data_structures::sync::MetadataRef;
221 use rustc_errors::{struct_span_err, DiagnosticBuilder};
222 use rustc_middle::middle::cstore::{CrateSource, MetadataLoader};
223 use rustc_session::config::{self, CrateType};
224 use rustc_session::filesearch::{FileDoesntMatch, FileMatches, FileSearch};
225 use rustc_session::search_paths::PathKind;
226 use rustc_session::{CrateDisambiguator, Session};
227 use rustc_span::symbol::{sym, Symbol};
228 use rustc_span::Span;
229 use rustc_target::spec::{Target, TargetTriple};
234 use std::io::{self, Read};
236 use std::path::{Path, PathBuf};
237 use std::time::Instant;
239 use flate2::read::DeflateDecoder;
241 use rustc_data_structures::owning_ref::OwningRef;
243 use log::{debug, info, warn};
246 struct CrateMismatch {
252 crate struct CrateLocator<'a> {
253 // Immutable per-session configuration.
255 metadata_loader: &'a dyn MetadataLoader,
257 // Immutable per-search configuration.
259 exact_paths: Vec<PathBuf>,
260 pub hash: Option<Svh>,
261 pub host_hash: Option<Svh>,
262 extra_filename: Option<&'a str>,
263 pub target: &'a Target,
264 pub triple: TargetTriple,
265 pub filesearch: FileSearch<'a>,
267 root: Option<&'a CratePaths>,
268 pub is_proc_macro: Option<bool>,
270 // Mutable in-progress state or output.
271 rejected_via_hash: Vec<CrateMismatch>,
272 rejected_via_triple: Vec<CrateMismatch>,
273 rejected_via_kind: Vec<CrateMismatch>,
274 rejected_via_version: Vec<CrateMismatch>,
275 rejected_via_filename: Vec<CrateMismatch>,
278 crate struct CratePaths {
284 crate fn new(name: Symbol, source: CrateSource) -> CratePaths {
285 CratePaths { name, source }
289 #[derive(Copy, Clone, PartialEq)]
296 impl fmt::Display for CrateFlavor {
297 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
298 f.write_str(match *self {
299 CrateFlavor::Rlib => "rlib",
300 CrateFlavor::Rmeta => "rmeta",
301 CrateFlavor::Dylib => "dylib",
306 impl<'a> CrateLocator<'a> {
309 metadata_loader: &'a dyn MetadataLoader,
312 host_hash: Option<Svh>,
313 extra_filename: Option<&'a str>,
317 root: Option<&'a CratePaths>,
318 is_proc_macro: Option<bool>,
319 ) -> CrateLocator<'a> {
324 exact_paths: if hash.is_none() {
327 .get(&crate_name.as_str())
329 .filter_map(|entry| entry.files())
334 // SVH being specified means this is a transitive dependency,
335 // so `--extern` options do not apply.
341 target: if is_host { &sess.host } else { &sess.target.target },
343 TargetTriple::from_triple(config::host_triple())
345 sess.opts.target_triple.clone()
347 filesearch: if is_host {
348 sess.host_filesearch(path_kind)
350 sess.target_filesearch(path_kind)
355 rejected_via_hash: Vec::new(),
356 rejected_via_triple: Vec::new(),
357 rejected_via_kind: Vec::new(),
358 rejected_via_version: Vec::new(),
359 rejected_via_filename: Vec::new(),
363 crate fn reset(&mut self) {
364 self.rejected_via_hash.clear();
365 self.rejected_via_triple.clear();
366 self.rejected_via_kind.clear();
367 self.rejected_via_version.clear();
368 self.rejected_via_filename.clear();
371 crate fn maybe_load_library_crate(&mut self) -> Option<Library> {
372 if !self.exact_paths.is_empty() {
373 return self.find_commandline_library();
375 let mut seen_paths = FxHashSet::default();
376 match self.extra_filename {
378 .find_library_crate(s, &mut seen_paths)
379 .or_else(|| self.find_library_crate("", &mut seen_paths)),
380 None => self.find_library_crate("", &mut seen_paths),
384 crate fn report_errs(self) -> ! {
385 let add = match self.root {
386 None => String::new(),
387 Some(r) => format!(" which `{}` depends on", r.name),
389 let mut msg = "the following crate versions were found:".to_string();
390 let mut err = if !self.rejected_via_hash.is_empty() {
391 let mut err = struct_span_err!(
395 "found possibly newer version of crate `{}`{}",
399 err.note("perhaps that crate needs to be recompiled?");
400 let mismatches = self.rejected_via_hash.iter();
401 for &CrateMismatch { ref path, .. } in mismatches {
402 msg.push_str(&format!("\ncrate `{}`: {}", self.crate_name, path.display()));
407 for path in r.source.paths() {
408 msg.push_str(&format!("\ncrate `{}`: {}", r.name, path.display()));
414 } else if !self.rejected_via_triple.is_empty() {
415 let mut err = struct_span_err!(
419 "couldn't find crate `{}` \
420 with expected target triple {}{}",
425 let mismatches = self.rejected_via_triple.iter();
426 for &CrateMismatch { ref path, ref got } in mismatches {
427 msg.push_str(&format!(
428 "\ncrate `{}`, target triple {}: {}",
436 } else if !self.rejected_via_kind.is_empty() {
437 let mut err = struct_span_err!(
441 "found staticlib `{}` instead of rlib or dylib{}",
445 err.help("please recompile that crate using --crate-type lib");
446 let mismatches = self.rejected_via_kind.iter();
447 for &CrateMismatch { ref path, .. } in mismatches {
448 msg.push_str(&format!("\ncrate `{}`: {}", self.crate_name, path.display()));
452 } else if !self.rejected_via_version.is_empty() {
453 let mut err = struct_span_err!(
457 "found crate `{}` compiled by an incompatible version \
463 "please recompile that crate using this compiler ({})",
466 let mismatches = self.rejected_via_version.iter();
467 for &CrateMismatch { ref path, ref got } in mismatches {
468 msg.push_str(&format!(
469 "\ncrate `{}` compiled by {}: {}",
478 let mut err = struct_span_err!(
482 "can't find crate for `{}`{}",
487 if (self.crate_name == sym::std || self.crate_name == sym::core)
488 && self.triple != TargetTriple::from_triple(config::host_triple())
490 err.note(&format!("the `{}` target may not be installed", self.triple));
491 } else if self.crate_name == sym::profiler_builtins {
492 err.note(&"the compiler may have been built without the profiler runtime");
494 err.span_label(self.span, "can't find crate");
498 if !self.rejected_via_filename.is_empty() {
499 let dylibname = self.dylibname();
500 let mismatches = self.rejected_via_filename.iter();
501 for &CrateMismatch { ref path, .. } in mismatches {
503 "extern location for {} is of an unknown type: {}",
508 "file name should be lib*.rlib or {}*.{}",
509 dylibname.0, dylibname.1
515 self.sess.abort_if_errors();
519 fn find_library_crate(
522 seen_paths: &mut FxHashSet<PathBuf>,
523 ) -> Option<Library> {
524 let dypair = self.dylibname();
525 let staticpair = self.staticlibname();
527 // want: crate_name.dir_part() + prefix + crate_name.file_part + "-"
528 let dylib_prefix = format!("{}{}{}", dypair.0, self.crate_name, extra_prefix);
529 let rlib_prefix = format!("lib{}{}", self.crate_name, extra_prefix);
530 let staticlib_prefix = format!("{}{}{}", staticpair.0, self.crate_name, extra_prefix);
532 let mut candidates: FxHashMap<_, (FxHashMap<_, _>, FxHashMap<_, _>, FxHashMap<_, _>)> =
534 let mut staticlibs = vec![];
536 // First, find all possible candidate rlibs and dylibs purely based on
537 // the name of the files themselves. We're trying to match against an
538 // exact crate name and a possibly an exact hash.
540 // During this step, we can filter all found libraries based on the
541 // name and id found in the crate id (we ignore the path portion for
542 // filename matching), as well as the exact hash (if specified). If we
543 // end up having many candidates, we must look at the metadata to
544 // perform exact matches against hashes/crate ids. Note that opening up
545 // the metadata is where we do an exact match against the full contents
546 // of the crate id (path/name/id).
548 // The goal of this step is to look at as little metadata as possible.
549 self.filesearch.search(|spf, kind| {
550 let file = match &spf.file_name_str {
551 None => return FileDoesntMatch,
554 let (hash, found_kind) = if file.starts_with(&rlib_prefix) && file.ends_with(".rlib") {
555 (&file[(rlib_prefix.len())..(file.len() - ".rlib".len())], CrateFlavor::Rlib)
556 } else if file.starts_with(&rlib_prefix) && file.ends_with(".rmeta") {
557 (&file[(rlib_prefix.len())..(file.len() - ".rmeta".len())], CrateFlavor::Rmeta)
558 } else if file.starts_with(&dylib_prefix) && file.ends_with(&dypair.1) {
559 (&file[(dylib_prefix.len())..(file.len() - dypair.1.len())], CrateFlavor::Dylib)
561 if file.starts_with(&staticlib_prefix) && file.ends_with(&staticpair.1) {
563 .push(CrateMismatch { path: spf.path.clone(), got: "static".to_string() });
565 return FileDoesntMatch;
568 info!("lib candidate: {}", spf.path.display());
570 let hash_str = hash.to_string();
571 let slot = candidates.entry(hash_str).or_default();
572 let (ref mut rlibs, ref mut rmetas, ref mut dylibs) = *slot;
573 fs::canonicalize(&spf.path)
575 if seen_paths.contains(&p) {
576 return FileDoesntMatch;
578 seen_paths.insert(p.clone());
580 CrateFlavor::Rlib => {
581 rlibs.insert(p, kind);
583 CrateFlavor::Rmeta => {
584 rmetas.insert(p, kind);
586 CrateFlavor::Dylib => {
587 dylibs.insert(p, kind);
592 .unwrap_or(FileDoesntMatch)
594 self.rejected_via_kind.extend(staticlibs);
596 // We have now collected all known libraries into a set of candidates
597 // keyed of the filename hash listed. For each filename, we also have a
598 // list of rlibs/dylibs that apply. Here, we map each of these lists
599 // (per hash), to a Library candidate for returning.
601 // A Library candidate is created if the metadata for the set of
602 // libraries corresponds to the crate id and hash criteria that this
603 // search is being performed for.
604 let mut libraries = FxHashMap::default();
605 for (_hash, (rlibs, rmetas, dylibs)) in candidates {
606 if let Some((svh, lib)) = self.extract_lib(rlibs, rmetas, dylibs) {
607 libraries.insert(svh, lib);
611 // Having now translated all relevant found hashes into libraries, see
612 // what we've got and figure out if we found multiple candidates for
614 match libraries.len() {
616 1 => Some(libraries.into_iter().next().unwrap().1),
618 let mut err = struct_span_err!(
622 "multiple matching crates for `{}`",
625 let candidates = libraries
627 .filter_map(|(_, lib)| {
628 let crate_name = &lib.metadata.get_root().name().as_str();
629 match &(&lib.source.dylib, &lib.source.rlib) {
630 &(&Some((ref pd, _)), &Some((ref pr, _))) => Some(format!(
631 "\ncrate `{}`: {}\n{:>padding$}",
635 padding = 8 + crate_name.len()
637 &(&Some((ref p, _)), &None) | &(&None, &Some((ref p, _))) => {
638 Some(format!("\ncrate `{}`: {}", crate_name, p.display()))
640 &(&None, &None) => None,
643 .collect::<String>();
644 err.note(&format!("candidates:{}", candidates));
653 rlibs: FxHashMap<PathBuf, PathKind>,
654 rmetas: FxHashMap<PathBuf, PathKind>,
655 dylibs: FxHashMap<PathBuf, PathKind>,
656 ) -> Option<(Svh, Library)> {
658 // Order here matters, rmeta should come first. See comment in
659 // `extract_one` below.
660 let source = CrateSource {
661 rmeta: self.extract_one(rmetas, CrateFlavor::Rmeta, &mut slot),
662 rlib: self.extract_one(rlibs, CrateFlavor::Rlib, &mut slot),
663 dylib: self.extract_one(dylibs, CrateFlavor::Dylib, &mut slot),
665 slot.map(|(svh, metadata)| (svh, Library { source, metadata }))
668 fn needs_crate_flavor(&self, flavor: CrateFlavor) -> bool {
669 if flavor == CrateFlavor::Dylib && self.is_proc_macro == Some(true) {
673 // The all loop is because `--crate-type=rlib --crate-type=rlib` is
674 // legal and produces both inside this type.
675 let is_rlib = self.sess.crate_types().iter().all(|c| *c == CrateType::Rlib);
676 let needs_object_code = self.sess.opts.output_types.should_codegen();
677 // If we're producing an rlib, then we don't need object code.
678 // Or, if we're not producing object code, then we don't need it either
679 // (e.g., if we're a cdylib but emitting just metadata).
680 if is_rlib || !needs_object_code {
681 flavor == CrateFlavor::Rmeta
683 // we need all flavors (perhaps not true, but what we do for now)
688 // Attempts to extract *one* library from the set `m`. If the set has no
689 // elements, `None` is returned. If the set has more than one element, then
690 // the errors and notes are emitted about the set of libraries.
692 // With only one library in the set, this function will extract it, and then
693 // read the metadata from it if `*slot` is `None`. If the metadata couldn't
694 // be read, it is assumed that the file isn't a valid rust library (no
695 // errors are emitted).
698 m: FxHashMap<PathBuf, PathKind>,
700 slot: &mut Option<(Svh, MetadataBlob)>,
701 ) -> Option<(PathBuf, PathKind)> {
702 let mut ret: Option<(PathBuf, PathKind)> = None;
705 // If we are producing an rlib, and we've already loaded metadata, then
706 // we should not attempt to discover further crate sources (unless we're
707 // locating a proc macro; exact logic is in needs_crate_flavor). This means
708 // that under -Zbinary-dep-depinfo we will not emit a dependency edge on
709 // the *unused* rlib, and by returning `None` here immediately we
710 // guarantee that we do indeed not use it.
712 // See also #68149 which provides more detail on why emitting the
713 // dependency on the rlib is a bad thing.
715 // We currently do not verify that these other sources are even in sync,
716 // and this is arguably a bug (see #10786), but because reading metadata
717 // is quite slow (especially from dylibs) we currently do not read it
718 // from the other crate sources.
720 if m.is_empty() || !self.needs_crate_flavor(flavor) {
722 } else if m.len() == 1 {
723 return Some(m.into_iter().next().unwrap());
727 let mut err: Option<DiagnosticBuilder<'_>> = None;
728 for (lib, kind) in m {
729 info!("{} reading metadata from: {}", flavor, lib.display());
730 let (hash, metadata) =
731 match get_metadata_section(self.target, flavor, &lib, self.metadata_loader) {
733 if let Some(h) = self.crate_matches(&blob, &lib) {
736 info!("metadata mismatch");
741 warn!("no metadata found: {}", err);
745 // If we see multiple hashes, emit an error about duplicate candidates.
746 if slot.as_ref().map_or(false, |s| s.0 != hash) {
747 let mut e = struct_span_err!(
751 "multiple {} candidates for `{}` found",
757 &format!(r"candidate #1: {}", ret.as_ref().unwrap().0.display()),
759 if let Some(ref mut e) = err {
770 .span_note(self.span, &format!(r"candidate #{}: {}", error, lib.display()));
774 // Ok so at this point we've determined that `(lib, kind)` above is
775 // a candidate crate to load, and that `slot` is either none (this
776 // is the first crate of its kind) or if some the previous path has
777 // the exact same hash (e.g., it's the exact same crate).
779 // In principle these two candidate crates are exactly the same so
780 // we can choose either of them to link. As a stupidly gross hack,
781 // however, we favor crate in the sysroot.
783 // You can find more info in rust-lang/rust#39518 and various linked
784 // issues, but the general gist is that during testing libstd the
785 // compilers has two candidates to choose from: one in the sysroot
786 // and one in the deps folder. These two crates are the exact same
787 // crate but if the compiler chooses the one in the deps folder
788 // it'll cause spurious errors on Windows.
790 // As a result, we favor the sysroot crate here. Note that the
791 // candidates are all canonicalized, so we canonicalize the sysroot
793 if let Some((ref prev, _)) = ret {
794 let sysroot = &self.sess.sysroot;
795 let sysroot = sysroot.canonicalize().unwrap_or_else(|_| sysroot.to_path_buf());
796 if prev.starts_with(&sysroot) {
800 *slot = Some((hash, metadata));
801 ret = Some((lib, kind));
812 fn crate_matches(&mut self, metadata: &MetadataBlob, libpath: &Path) -> Option<Svh> {
813 let rustc_version = rustc_version();
814 let found_version = metadata.get_rustc_version();
815 if found_version != rustc_version {
816 info!("Rejecting via version: expected {} got {}", rustc_version, found_version);
817 self.rejected_via_version
818 .push(CrateMismatch { path: libpath.to_path_buf(), got: found_version });
822 let root = metadata.get_root();
823 if let Some(expected_is_proc_macro) = self.is_proc_macro {
824 let is_proc_macro = root.is_proc_macro_crate();
825 if is_proc_macro != expected_is_proc_macro {
827 "Rejecting via proc macro: expected {} got {}",
828 expected_is_proc_macro, is_proc_macro
834 if self.exact_paths.is_empty() {
835 if self.crate_name != root.name() {
836 info!("Rejecting via crate name");
841 if root.triple() != &self.triple {
842 info!("Rejecting via crate triple: expected {} got {}", self.triple, root.triple());
843 self.rejected_via_triple.push(CrateMismatch {
844 path: libpath.to_path_buf(),
845 got: root.triple().to_string(),
850 let hash = root.hash();
851 if let Some(expected_hash) = self.hash {
852 if hash != expected_hash {
853 info!("Rejecting via hash: expected {} got {}", expected_hash, hash);
854 self.rejected_via_hash
855 .push(CrateMismatch { path: libpath.to_path_buf(), got: hash.to_string() });
863 // Returns the corresponding (prefix, suffix) that files need to have for
865 fn dylibname(&self) -> (String, String) {
866 let t = &self.target;
867 (t.options.dll_prefix.clone(), t.options.dll_suffix.clone())
870 // Returns the corresponding (prefix, suffix) that files need to have for
872 fn staticlibname(&self) -> (String, String) {
873 let t = &self.target;
874 (t.options.staticlib_prefix.clone(), t.options.staticlib_suffix.clone())
877 fn find_commandline_library(&mut self) -> Option<Library> {
878 // First, filter out all libraries that look suspicious. We only accept
879 // files which actually exist that have the correct naming scheme for
881 let sess = self.sess;
882 let dylibname = self.dylibname();
883 let mut rlibs = FxHashMap::default();
884 let mut rmetas = FxHashMap::default();
885 let mut dylibs = FxHashMap::default();
887 let crate_name = self.crate_name;
888 let rejected_via_filename = &mut self.rejected_via_filename;
889 let locs = self.exact_paths.iter().filter(|loc| {
892 "extern location for {} does not exist: {}",
898 let file = match loc.file_name().and_then(|s| s.to_str()) {
902 "extern location for {} is not a file: {}",
909 if file.starts_with("lib") && (file.ends_with(".rlib") || file.ends_with(".rmeta"))
913 let (ref prefix, ref suffix) = dylibname;
914 if file.starts_with(&prefix[..]) && file.ends_with(&suffix[..]) {
919 rejected_via_filename
920 .push(CrateMismatch { path: (*loc).clone(), got: String::new() });
925 // Now that we have an iterator of good candidates, make sure
926 // there's at most one rlib and at most one dylib.
928 if loc.file_name().unwrap().to_str().unwrap().ends_with(".rlib") {
929 rlibs.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag);
930 } else if loc.file_name().unwrap().to_str().unwrap().ends_with(".rmeta") {
931 rmetas.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag);
933 dylibs.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag);
938 // Extract the dylib/rlib/rmeta triple.
939 self.extract_lib(rlibs, rmetas, dylibs).map(|(_, lib)| lib)
943 // Just a small wrapper to time how long reading metadata takes.
944 fn get_metadata_section(
948 loader: &dyn MetadataLoader,
949 ) -> Result<MetadataBlob, String> {
950 let start = Instant::now();
951 let ret = get_metadata_section_imp(target, flavor, filename, loader);
952 info!("reading {:?} => {:?}", filename.file_name().unwrap(), start.elapsed());
956 /// A trivial wrapper for `Mmap` that implements `StableDeref`.
957 struct StableDerefMmap(memmap::Mmap);
959 impl Deref for StableDerefMmap {
962 fn deref(&self) -> &[u8] {
967 unsafe impl stable_deref_trait::StableDeref for StableDerefMmap {}
969 fn get_metadata_section_imp(
973 loader: &dyn MetadataLoader,
974 ) -> Result<MetadataBlob, String> {
975 if !filename.exists() {
976 return Err(format!("no such file: '{}'", filename.display()));
978 let raw_bytes: MetadataRef = match flavor {
979 CrateFlavor::Rlib => loader.get_rlib_metadata(target, filename)?,
980 CrateFlavor::Dylib => {
981 let buf = loader.get_dylib_metadata(target, filename)?;
982 // The header is uncompressed
983 let header_len = METADATA_HEADER.len();
984 debug!("checking {} bytes of metadata-version stamp", header_len);
985 let header = &buf[..cmp::min(header_len, buf.len())];
986 if header != METADATA_HEADER {
988 "incompatible metadata version found: '{}'",
993 // Header is okay -> inflate the actual metadata
994 let compressed_bytes = &buf[header_len..];
995 debug!("inflating {} bytes of compressed metadata", compressed_bytes.len());
996 let mut inflated = Vec::new();
997 match DeflateDecoder::new(compressed_bytes).read_to_end(&mut inflated) {
998 Ok(_) => rustc_erase_owner!(OwningRef::new(inflated).map_owner_box()),
1000 return Err(format!("failed to decompress metadata: {}", filename.display()));
1004 CrateFlavor::Rmeta => {
1005 // mmap the file, because only a small fraction of it is read.
1006 let file = std::fs::File::open(filename)
1007 .map_err(|_| format!("failed to open rmeta metadata: '{}'", filename.display()))?;
1008 let mmap = unsafe { memmap::Mmap::map(&file) };
1010 .map_err(|_| format!("failed to mmap rmeta metadata: '{}'", filename.display()))?;
1012 rustc_erase_owner!(OwningRef::new(StableDerefMmap(mmap)).map_owner_box())
1015 let blob = MetadataBlob::new(raw_bytes);
1016 if blob.is_compatible() {
1019 Err(format!("incompatible metadata version found: '{}'", filename.display()))
1023 /// Look for a plugin registrar. Returns its library path and crate disambiguator.
1024 pub fn find_plugin_registrar(
1026 metadata_loader: &dyn MetadataLoader,
1029 ) -> Option<(PathBuf, CrateDisambiguator)> {
1030 info!("find plugin registrar `{}`", name);
1031 let target_triple = sess.opts.target_triple.clone();
1032 let host_triple = TargetTriple::from_triple(config::host_triple());
1033 let is_cross = target_triple != host_triple;
1034 let mut target_only = false;
1035 let mut locator = CrateLocator::new(
1041 None, // extra_filename
1046 None, // is_proc_macro
1049 let library = locator.maybe_load_library_crate().or_else(|| {
1053 // Try loading from target crates. This will abort later if we
1054 // try to load a plugin registrar function,
1057 locator.target = &sess.target.target;
1058 locator.triple = target_triple;
1059 locator.filesearch = sess.target_filesearch(PathKind::Crate);
1061 locator.maybe_load_library_crate()
1063 let library = match library {
1065 None => locator.report_errs(),
1069 let message = format!(
1070 "plugin `{}` is not available for triple `{}` (only found {})",
1072 config::host_triple(),
1073 sess.opts.target_triple
1075 struct_span_err!(sess, span, E0456, "{}", &message).emit();
1079 match library.source.dylib {
1080 Some(dylib) => Some((dylib.0, library.metadata.get_root().disambiguator())),
1086 "plugin `{}` only found in rlib format, but must be available \
1091 // No need to abort because the loading code will just ignore this
1098 /// A diagnostic function for dumping crate metadata to an output stream.
1099 pub fn list_file_metadata(
1102 metadata_loader: &dyn MetadataLoader,
1103 out: &mut dyn io::Write,
1104 ) -> io::Result<()> {
1105 let filename = path.file_name().unwrap().to_str().unwrap();
1106 let flavor = if filename.ends_with(".rlib") {
1108 } else if filename.ends_with(".rmeta") {
1113 match get_metadata_section(target, flavor, path, metadata_loader) {
1114 Ok(metadata) => metadata.list_crate_metadata(out),
1115 Err(msg) => write!(out, "{}\n", msg),