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::middle::cstore::{CrateSource, MetadataLoader};
219 use rustc::session::filesearch::{FileDoesntMatch, FileMatches, FileSearch};
220 use rustc::session::search_paths::PathKind;
221 use rustc::session::{config, CrateDisambiguator, Session};
222 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
223 use rustc_data_structures::svh::Svh;
224 use rustc_data_structures::sync::MetadataRef;
225 use rustc_errors::{struct_span_err, DiagnosticBuilder};
226 use rustc_span::symbol::{sym, Symbol};
227 use rustc_span::Span;
228 use rustc_target::spec::{Target, TargetTriple};
233 use std::io::{self, Read};
235 use std::path::{Path, PathBuf};
236 use std::time::Instant;
238 use flate2::read::DeflateDecoder;
240 use rustc_data_structures::owning_ref::OwningRef;
242 use log::{debug, info, warn};
245 struct CrateMismatch {
251 crate struct CrateLocator<'a> {
252 // Immutable per-session configuration.
254 metadata_loader: &'a dyn MetadataLoader,
256 // Immutable per-search configuration.
258 exact_paths: Vec<PathBuf>,
259 pub hash: Option<Svh>,
260 pub host_hash: Option<Svh>,
261 extra_filename: Option<&'a str>,
262 pub target: &'a Target,
263 pub triple: TargetTriple,
264 pub filesearch: FileSearch<'a>,
266 root: Option<&'a CratePaths>,
267 pub is_proc_macro: Option<bool>,
269 // Mutable in-progress state or output.
270 rejected_via_hash: Vec<CrateMismatch>,
271 rejected_via_triple: Vec<CrateMismatch>,
272 rejected_via_kind: Vec<CrateMismatch>,
273 rejected_via_version: Vec<CrateMismatch>,
274 rejected_via_filename: Vec<CrateMismatch>,
277 crate struct CratePaths {
283 crate fn new(name: Symbol, source: CrateSource) -> CratePaths {
284 CratePaths { name, source }
288 #[derive(Copy, Clone, PartialEq)]
295 impl fmt::Display for CrateFlavor {
296 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
297 f.write_str(match *self {
298 CrateFlavor::Rlib => "rlib",
299 CrateFlavor::Rmeta => "rmeta",
300 CrateFlavor::Dylib => "dylib",
305 impl<'a> CrateLocator<'a> {
308 metadata_loader: &'a dyn MetadataLoader,
311 host_hash: Option<Svh>,
312 extra_filename: Option<&'a str>,
316 root: Option<&'a CratePaths>,
317 is_proc_macro: Option<bool>,
318 ) -> CrateLocator<'a> {
323 exact_paths: if hash.is_none() {
326 .get(&crate_name.as_str())
328 .filter_map(|entry| entry.files())
330 .map(|location| PathBuf::from(location))
333 // SVH being specified means this is a transitive dependency,
334 // so `--extern` options do not apply.
340 target: if is_host { &sess.host } else { &sess.target.target },
342 TargetTriple::from_triple(config::host_triple())
344 sess.opts.target_triple.clone()
346 filesearch: if is_host {
347 sess.host_filesearch(path_kind)
349 sess.target_filesearch(path_kind)
354 rejected_via_hash: Vec::new(),
355 rejected_via_triple: Vec::new(),
356 rejected_via_kind: Vec::new(),
357 rejected_via_version: Vec::new(),
358 rejected_via_filename: Vec::new(),
362 crate fn reset(&mut self) {
363 self.rejected_via_hash.clear();
364 self.rejected_via_triple.clear();
365 self.rejected_via_kind.clear();
366 self.rejected_via_version.clear();
367 self.rejected_via_filename.clear();
370 crate fn maybe_load_library_crate(&mut self) -> Option<Library> {
371 if !self.exact_paths.is_empty() {
372 return self.find_commandline_library();
374 let mut seen_paths = FxHashSet::default();
375 match self.extra_filename {
377 .find_library_crate(s, &mut seen_paths)
378 .or_else(|| self.find_library_crate("", &mut seen_paths)),
379 None => self.find_library_crate("", &mut seen_paths),
383 crate fn report_errs(self) -> ! {
384 let add = match self.root {
385 None => String::new(),
386 Some(r) => format!(" which `{}` depends on", r.name),
388 let mut msg = "the following crate versions were found:".to_string();
389 let mut err = if !self.rejected_via_hash.is_empty() {
390 let mut err = struct_span_err!(
394 "found possibly newer version of crate `{}`{}",
398 err.note("perhaps that crate needs to be recompiled?");
399 let mismatches = self.rejected_via_hash.iter();
400 for &CrateMismatch { ref path, .. } in mismatches {
401 msg.push_str(&format!("\ncrate `{}`: {}", self.crate_name, path.display()));
406 for path in r.source.paths() {
407 msg.push_str(&format!("\ncrate `{}`: {}", r.name, path.display()));
413 } else if !self.rejected_via_triple.is_empty() {
414 let mut err = struct_span_err!(
418 "couldn't find crate `{}` \
419 with expected target triple {}{}",
424 let mismatches = self.rejected_via_triple.iter();
425 for &CrateMismatch { ref path, ref got } in mismatches {
426 msg.push_str(&format!(
427 "\ncrate `{}`, target triple {}: {}",
435 } else if !self.rejected_via_kind.is_empty() {
436 let mut err = struct_span_err!(
440 "found staticlib `{}` instead of rlib or dylib{}",
444 err.help("please recompile that crate using --crate-type lib");
445 let mismatches = self.rejected_via_kind.iter();
446 for &CrateMismatch { ref path, .. } in mismatches {
447 msg.push_str(&format!("\ncrate `{}`: {}", self.crate_name, path.display()));
451 } else if !self.rejected_via_version.is_empty() {
452 let mut err = struct_span_err!(
456 "found crate `{}` compiled by an incompatible version \
462 "please recompile that crate using this compiler ({})",
465 let mismatches = self.rejected_via_version.iter();
466 for &CrateMismatch { ref path, ref got } in mismatches {
467 msg.push_str(&format!(
468 "\ncrate `{}` compiled by {}: {}",
477 let mut err = struct_span_err!(
481 "can't find crate for `{}`{}",
486 if (self.crate_name == sym::std || self.crate_name == sym::core)
487 && self.triple != TargetTriple::from_triple(config::host_triple())
489 err.note(&format!("the `{}` target may not be installed", self.triple));
491 err.span_label(self.span, "can't find crate");
495 if !self.rejected_via_filename.is_empty() {
496 let dylibname = self.dylibname();
497 let mismatches = self.rejected_via_filename.iter();
498 for &CrateMismatch { ref path, .. } in mismatches {
500 "extern location for {} is of an unknown type: {}",
505 "file name should be lib*.rlib or {}*.{}",
506 dylibname.0, dylibname.1
512 self.sess.abort_if_errors();
516 fn find_library_crate(
519 seen_paths: &mut FxHashSet<PathBuf>,
520 ) -> Option<Library> {
521 let dypair = self.dylibname();
522 let staticpair = self.staticlibname();
524 // want: crate_name.dir_part() + prefix + crate_name.file_part + "-"
525 let dylib_prefix = format!("{}{}{}", dypair.0, self.crate_name, extra_prefix);
526 let rlib_prefix = format!("lib{}{}", self.crate_name, extra_prefix);
527 let staticlib_prefix = format!("{}{}{}", staticpair.0, self.crate_name, extra_prefix);
529 let mut candidates: FxHashMap<_, (FxHashMap<_, _>, FxHashMap<_, _>, FxHashMap<_, _>)> =
531 let mut staticlibs = vec![];
533 // First, find all possible candidate rlibs and dylibs purely based on
534 // the name of the files themselves. We're trying to match against an
535 // exact crate name and a possibly an exact hash.
537 // During this step, we can filter all found libraries based on the
538 // name and id found in the crate id (we ignore the path portion for
539 // filename matching), as well as the exact hash (if specified). If we
540 // end up having many candidates, we must look at the metadata to
541 // perform exact matches against hashes/crate ids. Note that opening up
542 // the metadata is where we do an exact match against the full contents
543 // of the crate id (path/name/id).
545 // The goal of this step is to look at as little metadata as possible.
546 self.filesearch.search(|path, kind| {
547 let file = match path.file_name().and_then(|s| s.to_str()) {
548 None => return FileDoesntMatch,
551 let (hash, found_kind) = if file.starts_with(&rlib_prefix) && file.ends_with(".rlib") {
552 (&file[(rlib_prefix.len())..(file.len() - ".rlib".len())], CrateFlavor::Rlib)
553 } else if file.starts_with(&rlib_prefix) && file.ends_with(".rmeta") {
554 (&file[(rlib_prefix.len())..(file.len() - ".rmeta".len())], CrateFlavor::Rmeta)
555 } else if file.starts_with(&dylib_prefix) && file.ends_with(&dypair.1) {
556 (&file[(dylib_prefix.len())..(file.len() - dypair.1.len())], CrateFlavor::Dylib)
558 if file.starts_with(&staticlib_prefix) && file.ends_with(&staticpair.1) {
559 staticlibs.push(CrateMismatch {
560 path: path.to_path_buf(),
561 got: "static".to_string(),
564 return FileDoesntMatch;
567 info!("lib candidate: {}", path.display());
569 let hash_str = hash.to_string();
570 let slot = candidates.entry(hash_str).or_default();
571 let (ref mut rlibs, ref mut rmetas, ref mut dylibs) = *slot;
572 fs::canonicalize(path)
574 if seen_paths.contains(&p) {
575 return FileDoesntMatch;
577 seen_paths.insert(p.clone());
579 CrateFlavor::Rlib => {
580 rlibs.insert(p, kind);
582 CrateFlavor::Rmeta => {
583 rmetas.insert(p, kind);
585 CrateFlavor::Dylib => {
586 dylibs.insert(p, kind);
591 .unwrap_or(FileDoesntMatch)
593 self.rejected_via_kind.extend(staticlibs);
595 // We have now collected all known libraries into a set of candidates
596 // keyed of the filename hash listed. For each filename, we also have a
597 // list of rlibs/dylibs that apply. Here, we map each of these lists
598 // (per hash), to a Library candidate for returning.
600 // A Library candidate is created if the metadata for the set of
601 // libraries corresponds to the crate id and hash criteria that this
602 // search is being performed for.
603 let mut libraries = FxHashMap::default();
604 for (_hash, (rlibs, rmetas, dylibs)) in candidates {
605 if let Some((svh, lib)) = self.extract_lib(rlibs, rmetas, dylibs) {
606 libraries.insert(svh, lib);
610 // Having now translated all relevant found hashes into libraries, see
611 // what we've got and figure out if we found multiple candidates for
613 match libraries.len() {
615 1 => Some(libraries.into_iter().next().unwrap().1),
617 let mut err = struct_span_err!(
621 "multiple matching crates for `{}`",
624 let candidates = libraries
626 .filter_map(|(_, lib)| {
627 let crate_name = &lib.metadata.get_root().name().as_str();
628 match &(&lib.source.dylib, &lib.source.rlib) {
629 &(&Some((ref pd, _)), &Some((ref pr, _))) => Some(format!(
630 "\ncrate `{}`: {}\n{:>padding$}",
634 padding = 8 + crate_name.len()
636 &(&Some((ref p, _)), &None) | &(&None, &Some((ref p, _))) => {
637 Some(format!("\ncrate `{}`: {}", crate_name, p.display()))
639 &(&None, &None) => None,
642 .collect::<String>();
643 err.note(&format!("candidates:{}", candidates));
652 rlibs: FxHashMap<PathBuf, PathKind>,
653 rmetas: FxHashMap<PathBuf, PathKind>,
654 dylibs: FxHashMap<PathBuf, PathKind>,
655 ) -> Option<(Svh, Library)> {
657 // Order here matters, rmeta should come first. See comment in
658 // `extract_one` below.
659 let source = CrateSource {
660 rmeta: self.extract_one(rmetas, CrateFlavor::Rmeta, &mut slot),
661 rlib: self.extract_one(rlibs, CrateFlavor::Rlib, &mut slot),
662 dylib: self.extract_one(dylibs, CrateFlavor::Dylib, &mut slot),
664 slot.map(|(svh, metadata)| (svh, Library { source, metadata }))
667 fn needs_crate_flavor(&self, flavor: CrateFlavor) -> bool {
668 if flavor == CrateFlavor::Dylib && self.is_proc_macro == Some(true) {
672 // The all loop is because `--crate-type=rlib --crate-type=rlib` is
673 // legal and produces both inside this type.
674 let is_rlib = self.sess.crate_types.borrow().iter().all(|c| *c == config::CrateType::Rlib);
675 let needs_object_code = self.sess.opts.output_types.should_codegen();
676 // If we're producing an rlib, then we don't need object code.
677 // Or, if we're not producing object code, then we don't need it either
678 // (e.g., if we're a cdylib but emitting just metadata).
679 if is_rlib || !needs_object_code {
680 flavor == CrateFlavor::Rmeta
682 // we need all flavors (perhaps not true, but what we do for now)
687 // Attempts to extract *one* library from the set `m`. If the set has no
688 // elements, `None` is returned. If the set has more than one element, then
689 // the errors and notes are emitted about the set of libraries.
691 // With only one library in the set, this function will extract it, and then
692 // read the metadata from it if `*slot` is `None`. If the metadata couldn't
693 // be read, it is assumed that the file isn't a valid rust library (no
694 // errors are emitted).
697 m: FxHashMap<PathBuf, PathKind>,
699 slot: &mut Option<(Svh, MetadataBlob)>,
700 ) -> Option<(PathBuf, PathKind)> {
701 let mut ret: Option<(PathBuf, PathKind)> = None;
704 // If we are producing an rlib, and we've already loaded metadata, then
705 // we should not attempt to discover further crate sources (unless we're
706 // locating a proc macro; exact logic is in needs_crate_flavor). This means
707 // that under -Zbinary-dep-depinfo we will not emit a dependency edge on
708 // the *unused* rlib, and by returning `None` here immediately we
709 // guarantee that we do indeed not use it.
711 // See also #68149 which provides more detail on why emitting the
712 // dependency on the rlib is a bad thing.
714 // We currenty do not verify that these other sources are even in sync,
715 // and this is arguably a bug (see #10786), but because reading metadata
716 // is quite slow (especially from dylibs) we currently do not read it
717 // from the other crate sources.
719 if m.is_empty() || !self.needs_crate_flavor(flavor) {
721 } else if m.len() == 1 {
722 return Some(m.into_iter().next().unwrap());
726 let mut err: Option<DiagnosticBuilder<'_>> = None;
727 for (lib, kind) in m {
728 info!("{} reading metadata from: {}", flavor, lib.display());
729 let (hash, metadata) =
730 match get_metadata_section(self.target, flavor, &lib, self.metadata_loader) {
732 if let Some(h) = self.crate_matches(&blob, &lib) {
735 info!("metadata mismatch");
740 warn!("no metadata found: {}", err);
744 // If we see multiple hashes, emit an error about duplicate candidates.
745 if slot.as_ref().map_or(false, |s| s.0 != hash) {
746 let mut e = struct_span_err!(
750 "multiple {} candidates for `{}` found",
756 &format!(r"candidate #1: {}", ret.as_ref().unwrap().0.display()),
758 if let Some(ref mut e) = err {
769 .span_note(self.span, &format!(r"candidate #{}: {}", error, lib.display()));
773 // Ok so at this point we've determined that `(lib, kind)` above is
774 // a candidate crate to load, and that `slot` is either none (this
775 // is the first crate of its kind) or if some the previous path has
776 // the exact same hash (e.g., it's the exact same crate).
778 // In principle these two candidate crates are exactly the same so
779 // we can choose either of them to link. As a stupidly gross hack,
780 // however, we favor crate in the sysroot.
782 // You can find more info in rust-lang/rust#39518 and various linked
783 // issues, but the general gist is that during testing libstd the
784 // compilers has two candidates to choose from: one in the sysroot
785 // and one in the deps folder. These two crates are the exact same
786 // crate but if the compiler chooses the one in the deps folder
787 // it'll cause spurious errors on Windows.
789 // As a result, we favor the sysroot crate here. Note that the
790 // candidates are all canonicalized, so we canonicalize the sysroot
792 if let Some((ref prev, _)) = ret {
793 let sysroot = &self.sess.sysroot;
794 let sysroot = sysroot.canonicalize().unwrap_or_else(|_| sysroot.to_path_buf());
795 if prev.starts_with(&sysroot) {
799 *slot = Some((hash, metadata));
800 ret = Some((lib, kind));
811 fn crate_matches(&mut self, metadata: &MetadataBlob, libpath: &Path) -> Option<Svh> {
812 let rustc_version = rustc_version();
813 let found_version = metadata.get_rustc_version();
814 if found_version != rustc_version {
815 info!("Rejecting via version: expected {} got {}", rustc_version, found_version);
816 self.rejected_via_version
817 .push(CrateMismatch { path: libpath.to_path_buf(), got: found_version });
821 let root = metadata.get_root();
822 if let Some(expected_is_proc_macro) = self.is_proc_macro {
823 let is_proc_macro = root.is_proc_macro_crate();
824 if is_proc_macro != expected_is_proc_macro {
826 "Rejecting via proc macro: expected {} got {}",
827 expected_is_proc_macro, is_proc_macro
833 if self.exact_paths.is_empty() {
834 if self.crate_name != root.name() {
835 info!("Rejecting via crate name");
840 if root.triple() != &self.triple {
841 info!("Rejecting via crate triple: expected {} got {}", self.triple, root.triple());
842 self.rejected_via_triple.push(CrateMismatch {
843 path: libpath.to_path_buf(),
844 got: root.triple().to_string(),
849 let hash = root.hash();
850 if let Some(expected_hash) = self.hash {
851 if hash != expected_hash {
852 info!("Rejecting via hash: expected {} got {}", expected_hash, hash);
853 self.rejected_via_hash
854 .push(CrateMismatch { path: libpath.to_path_buf(), got: hash.to_string() });
862 // Returns the corresponding (prefix, suffix) that files need to have for
864 fn dylibname(&self) -> (String, String) {
865 let t = &self.target;
866 (t.options.dll_prefix.clone(), t.options.dll_suffix.clone())
869 // Returns the corresponding (prefix, suffix) that files need to have for
871 fn staticlibname(&self) -> (String, String) {
872 let t = &self.target;
873 (t.options.staticlib_prefix.clone(), t.options.staticlib_suffix.clone())
876 fn find_commandline_library(&mut self) -> Option<Library> {
877 // First, filter out all libraries that look suspicious. We only accept
878 // files which actually exist that have the correct naming scheme for
880 let sess = self.sess;
881 let dylibname = self.dylibname();
882 let mut rlibs = FxHashMap::default();
883 let mut rmetas = FxHashMap::default();
884 let mut dylibs = FxHashMap::default();
886 let crate_name = self.crate_name;
887 let rejected_via_filename = &mut self.rejected_via_filename;
888 let locs = self.exact_paths.iter().filter(|loc| {
891 "extern location for {} does not exist: {}",
897 let file = match loc.file_name().and_then(|s| s.to_str()) {
901 "extern location for {} is not a file: {}",
908 if file.starts_with("lib") && (file.ends_with(".rlib") || file.ends_with(".rmeta"))
912 let (ref prefix, ref suffix) = dylibname;
913 if file.starts_with(&prefix[..]) && file.ends_with(&suffix[..]) {
918 rejected_via_filename
919 .push(CrateMismatch { path: (*loc).clone(), got: String::new() });
924 // Now that we have an iterator of good candidates, make sure
925 // there's at most one rlib and at most one dylib.
927 if loc.file_name().unwrap().to_str().unwrap().ends_with(".rlib") {
928 rlibs.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag);
929 } else if loc.file_name().unwrap().to_str().unwrap().ends_with(".rmeta") {
930 rmetas.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag);
932 dylibs.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag);
937 // Extract the dylib/rlib/rmeta triple.
938 self.extract_lib(rlibs, rmetas, dylibs).map(|(_, lib)| lib)
942 // Just a small wrapper to time how long reading metadata takes.
943 fn get_metadata_section(
947 loader: &dyn MetadataLoader,
948 ) -> Result<MetadataBlob, String> {
949 let start = Instant::now();
950 let ret = get_metadata_section_imp(target, flavor, filename, loader);
951 info!("reading {:?} => {:?}", filename.file_name().unwrap(), start.elapsed());
955 /// A trivial wrapper for `Mmap` that implements `StableDeref`.
956 struct StableDerefMmap(memmap::Mmap);
958 impl Deref for StableDerefMmap {
961 fn deref(&self) -> &[u8] {
966 unsafe impl stable_deref_trait::StableDeref for StableDerefMmap {}
968 fn get_metadata_section_imp(
972 loader: &dyn MetadataLoader,
973 ) -> Result<MetadataBlob, String> {
974 if !filename.exists() {
975 return Err(format!("no such file: '{}'", filename.display()));
977 let raw_bytes: MetadataRef = match flavor {
978 CrateFlavor::Rlib => loader.get_rlib_metadata(target, filename)?,
979 CrateFlavor::Dylib => {
980 let buf = loader.get_dylib_metadata(target, filename)?;
981 // The header is uncompressed
982 let header_len = METADATA_HEADER.len();
983 debug!("checking {} bytes of metadata-version stamp", header_len);
984 let header = &buf[..cmp::min(header_len, buf.len())];
985 if header != METADATA_HEADER {
987 "incompatible metadata version found: '{}'",
992 // Header is okay -> inflate the actual metadata
993 let compressed_bytes = &buf[header_len..];
994 debug!("inflating {} bytes of compressed metadata", compressed_bytes.len());
995 let mut inflated = Vec::new();
996 match DeflateDecoder::new(compressed_bytes).read_to_end(&mut inflated) {
997 Ok(_) => rustc_erase_owner!(OwningRef::new(inflated).map_owner_box()),
999 return Err(format!("failed to decompress metadata: {}", filename.display()));
1003 CrateFlavor::Rmeta => {
1004 // mmap the file, because only a small fraction of it is read.
1005 let file = std::fs::File::open(filename)
1006 .map_err(|_| format!("failed to open rmeta metadata: '{}'", filename.display()))?;
1007 let mmap = unsafe { memmap::Mmap::map(&file) };
1009 .map_err(|_| format!("failed to mmap rmeta metadata: '{}'", filename.display()))?;
1011 rustc_erase_owner!(OwningRef::new(StableDerefMmap(mmap)).map_owner_box())
1014 let blob = MetadataBlob::new(raw_bytes);
1015 if blob.is_compatible() {
1018 Err(format!("incompatible metadata version found: '{}'", filename.display()))
1022 /// Look for a plugin registrar. Returns its library path and crate disambiguator.
1023 pub fn find_plugin_registrar(
1025 metadata_loader: &dyn MetadataLoader,
1028 ) -> Option<(PathBuf, CrateDisambiguator)> {
1029 info!("find plugin registrar `{}`", name);
1030 let target_triple = sess.opts.target_triple.clone();
1031 let host_triple = TargetTriple::from_triple(config::host_triple());
1032 let is_cross = target_triple != host_triple;
1033 let mut target_only = false;
1034 let mut locator = CrateLocator::new(
1040 None, // extra_filename
1045 None, // is_proc_macro
1048 let library = locator.maybe_load_library_crate().or_else(|| {
1052 // Try loading from target crates. This will abort later if we
1053 // try to load a plugin registrar function,
1056 locator.target = &sess.target.target;
1057 locator.triple = target_triple;
1058 locator.filesearch = sess.target_filesearch(PathKind::Crate);
1060 locator.maybe_load_library_crate()
1062 let library = match library {
1064 None => locator.report_errs(),
1068 let message = format!(
1069 "plugin `{}` is not available for triple `{}` (only found {})",
1071 config::host_triple(),
1072 sess.opts.target_triple
1074 struct_span_err!(sess, span, E0456, "{}", &message).emit();
1078 match library.source.dylib {
1079 Some(dylib) => Some((dylib.0, library.metadata.get_root().disambiguator())),
1085 "plugin `{}` only found in rlib format, but must be available \
1090 // No need to abort because the loading code will just ignore this
1097 /// A diagnostic function for dumping crate metadata to an output stream.
1098 pub fn list_file_metadata(
1101 metadata_loader: &dyn MetadataLoader,
1102 out: &mut dyn io::Write,
1103 ) -> io::Result<()> {
1104 let filename = path.file_name().unwrap().to_str().unwrap();
1105 let flavor = if filename.ends_with(".rlib") {
1107 } else if filename.ends_with(".rmeta") {
1112 match get_metadata_section(target, flavor, path, metadata_loader) {
1113 Ok(metadata) => metadata.list_crate_metadata(out),
1114 Err(msg) => write!(out, "{}\n", msg),