1 // Copyright 2012-2015 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 //! Finds crate binaries and loads their metadata
13 //! Might I be the first to welcome you to a world of platform differences,
14 //! version requirements, dependency graphs, conflicting desires, and fun! This
15 //! is the major guts (along with metadata::creader) of the compiler for loading
16 //! crates and resolving dependencies. Let's take a tour!
20 //! Each invocation of the compiler is immediately concerned with one primary
21 //! problem, to connect a set of crates to resolved crates on the filesystem.
22 //! Concretely speaking, the compiler follows roughly these steps to get here:
24 //! 1. Discover a set of `extern crate` statements.
25 //! 2. Transform these directives into crate names. If the directive does not
26 //! have an explicit name, then the identifier is the name.
27 //! 3. For each of these crate names, find a corresponding crate on the
30 //! Sounds easy, right? Let's walk into some of the nuances.
32 //! ## Transitive Dependencies
34 //! Let's say we've got three crates: A, B, and C. A depends on B, and B depends
35 //! on C. When we're compiling A, we primarily need to find and locate B, but we
36 //! also end up needing to find and locate C as well.
38 //! The reason for this is that any of B's types could be composed of C's types,
39 //! any function in B could return a type from C, etc. To be able to guarantee
40 //! that we can always typecheck/translate any function, we have to have
41 //! complete knowledge of the whole ecosystem, not just our immediate
44 //! So now as part of the "find a corresponding crate on the filesystem" step
45 //! above, this involves also finding all crates for *all upstream
46 //! dependencies*. This includes all dependencies transitively.
48 //! ## Rlibs and Dylibs
50 //! The compiler has two forms of intermediate dependencies. These are dubbed
51 //! rlibs and dylibs for the static and dynamic variants, respectively. An rlib
52 //! is a rustc-defined file format (currently just an ar archive) while a dylib
53 //! is a platform-defined dynamic library. Each library has a metadata somewhere
56 //! When translating a crate name to a crate on the filesystem, we all of a
57 //! sudden need to take into account both rlibs and dylibs! Linkage later on may
58 //! use either one of these files, as each has their pros/cons. The job of crate
59 //! loading is to discover what's possible by finding all candidates.
61 //! Most parts of this loading systems keep the dylib/rlib as just separate
66 //! We can't exactly scan your whole hard drive when looking for dependencies,
67 //! so we need to places to look. Currently the compiler will implicitly add the
68 //! target lib search path ($prefix/lib/rustlib/$target/lib) to any compilation,
69 //! and otherwise all -L flags are added to the search paths.
71 //! ## What criterion to select on?
73 //! This a pretty tricky area of loading crates. Given a file, how do we know
74 //! whether it's the right crate? Currently, the rules look along these lines:
76 //! 1. Does the filename match an rlib/dylib pattern? That is to say, does the
77 //! filename have the right prefix/suffix?
78 //! 2. Does the filename have the right prefix for the crate name being queried?
79 //! This is filtering for files like `libfoo*.rlib` and such.
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:
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 cstore::MetadataBlob;
216 use creader::Library;
217 use schema::{METADATA_HEADER, rustc_version};
219 use rustc::hir::svh::Svh;
220 use rustc::session::{config, Session};
221 use rustc::session::filesearch::{FileSearch, FileMatches, FileDoesntMatch};
222 use rustc::session::search_paths::PathKind;
223 use rustc::util::common;
224 use rustc::util::nodemap::FxHashMap;
226 use rustc_llvm as llvm;
227 use rustc_llvm::{False, ObjectFile, mk_section_iter};
228 use rustc_llvm::archive_ro::ArchiveRO;
229 use errors::DiagnosticBuilder;
230 use syntax_pos::Span;
231 use rustc_back::target::Target;
237 use std::path::{Path, PathBuf};
240 use std::time::Instant;
244 pub struct CrateMismatch {
249 pub struct Context<'a> {
250 pub sess: &'a Session,
253 pub crate_name: &'a str,
254 pub hash: Option<&'a Svh>,
255 // points to either self.sess.target.target or self.sess.host, must match triple
256 pub target: &'a Target,
258 pub filesearch: FileSearch<'a>,
259 pub root: &'a Option<CratePaths>,
260 pub rejected_via_hash: Vec<CrateMismatch>,
261 pub rejected_via_triple: Vec<CrateMismatch>,
262 pub rejected_via_kind: Vec<CrateMismatch>,
263 pub rejected_via_version: Vec<CrateMismatch>,
264 pub should_match_name: bool,
265 pub is_proc_macro: Option<bool>,
268 pub struct ArchiveMetadata {
270 // points into self._archive
274 pub struct CratePaths {
276 pub dylib: Option<PathBuf>,
277 pub rlib: Option<PathBuf>,
280 pub const METADATA_FILENAME: &'static str = "rust.metadata.bin";
282 #[derive(Copy, Clone, PartialEq)]
288 impl fmt::Display for CrateFlavor {
289 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
290 f.write_str(match *self {
291 CrateFlavor::Rlib => "rlib",
292 CrateFlavor::Dylib => "dylib",
298 fn paths(&self) -> Vec<PathBuf> {
299 match (&self.dylib, &self.rlib) {
300 (&None, &None) => vec![],
301 (&Some(ref p), &None) |
302 (&None, &Some(ref p)) => vec![p.clone()],
303 (&Some(ref p1), &Some(ref p2)) => vec![p1.clone(), p2.clone()],
308 impl<'a> Context<'a> {
309 pub fn maybe_load_library_crate(&mut self) -> Option<Library> {
310 self.find_library_crate()
313 pub fn load_library_crate(&mut self) -> Library {
314 self.find_library_crate().unwrap_or_else(|| self.report_errs())
317 pub fn report_errs(&mut self) -> ! {
318 let add = match self.root {
319 &None => String::new(),
320 &Some(ref r) => format!(" which `{}` depends on", r.ident),
322 let mut err = if !self.rejected_via_hash.is_empty() {
323 struct_span_err!(self.sess,
326 "found possibly newer version of crate `{}`{}",
329 } else if !self.rejected_via_triple.is_empty() {
330 struct_span_err!(self.sess,
333 "couldn't find crate `{}` with expected target triple {}{}",
337 } else if !self.rejected_via_kind.is_empty() {
338 struct_span_err!(self.sess,
341 "found staticlib `{}` instead of rlib or dylib{}",
344 } else if !self.rejected_via_version.is_empty() {
345 struct_span_err!(self.sess,
348 "found crate `{}` compiled by an incompatible version of rustc{}",
352 let mut err = struct_span_err!(self.sess,
355 "can't find crate for `{}`{}",
359 if (self.ident == "std" || self.ident == "core")
360 && self.triple != config::host_triple() {
361 err.note(&format!("the `{}` target may not be installed", self.triple));
363 err.span_label(self.span, &format!("can't find crate"));
367 if !self.rejected_via_triple.is_empty() {
368 let mismatches = self.rejected_via_triple.iter();
369 for (i, &CrateMismatch { ref path, ref got }) in mismatches.enumerate() {
370 err.note(&format!("crate `{}`, path #{}, triple {}: {}",
377 if !self.rejected_via_hash.is_empty() {
378 err.note("perhaps that crate needs to be recompiled?");
379 let mismatches = self.rejected_via_hash.iter();
380 for (i, &CrateMismatch { ref path, .. }) in mismatches.enumerate() {
381 err.note(&format!("crate `{}` path #{}: {}", self.ident, i + 1, path.display()));
386 for (i, path) in r.paths().iter().enumerate() {
387 err.note(&format!("crate `{}` path #{}: {}",
395 if !self.rejected_via_kind.is_empty() {
396 err.help("please recompile that crate using --crate-type lib");
397 let mismatches = self.rejected_via_kind.iter();
398 for (i, &CrateMismatch { ref path, .. }) in mismatches.enumerate() {
399 err.note(&format!("crate `{}` path #{}: {}", self.ident, i + 1, path.display()));
402 if !self.rejected_via_version.is_empty() {
403 err.help(&format!("please recompile that crate using this compiler ({})",
405 let mismatches = self.rejected_via_version.iter();
406 for (i, &CrateMismatch { ref path, ref got }) in mismatches.enumerate() {
407 err.note(&format!("crate `{}` path #{}: {} compiled by {:?}",
416 self.sess.abort_if_errors();
420 fn find_library_crate(&mut self) -> Option<Library> {
421 // If an SVH is specified, then this is a transitive dependency that
422 // must be loaded via -L plus some filtering.
423 if self.hash.is_none() {
424 self.should_match_name = false;
425 if let Some(s) = self.sess.opts.externs.get(self.crate_name) {
426 return self.find_commandline_library(s.iter());
428 self.should_match_name = true;
431 let dypair = self.dylibname();
432 let staticpair = self.staticlibname();
434 // want: crate_name.dir_part() + prefix + crate_name.file_part + "-"
435 let dylib_prefix = format!("{}{}", dypair.0, self.crate_name);
436 let rlib_prefix = format!("lib{}", self.crate_name);
437 let staticlib_prefix = format!("{}{}", staticpair.0, self.crate_name);
439 let mut candidates = FxHashMap();
440 let mut staticlibs = vec![];
442 // First, find all possible candidate rlibs and dylibs purely based on
443 // the name of the files themselves. We're trying to match against an
444 // exact crate name and a possibly an exact hash.
446 // During this step, we can filter all found libraries based on the
447 // name and id found in the crate id (we ignore the path portion for
448 // filename matching), as well as the exact hash (if specified). If we
449 // end up having many candidates, we must look at the metadata to
450 // perform exact matches against hashes/crate ids. Note that opening up
451 // the metadata is where we do an exact match against the full contents
452 // of the crate id (path/name/id).
454 // The goal of this step is to look at as little metadata as possible.
455 self.filesearch.search(|path, kind| {
456 let file = match path.file_name().and_then(|s| s.to_str()) {
457 None => return FileDoesntMatch,
460 let (hash, rlib) = if file.starts_with(&rlib_prefix[..]) && file.ends_with(".rlib") {
461 (&file[(rlib_prefix.len())..(file.len() - ".rlib".len())], true)
462 } else if file.starts_with(&dylib_prefix) &&
463 file.ends_with(&dypair.1) {
464 (&file[(dylib_prefix.len())..(file.len() - dypair.1.len())], false)
466 if file.starts_with(&staticlib_prefix[..]) && file.ends_with(&staticpair.1) {
467 staticlibs.push(CrateMismatch {
468 path: path.to_path_buf(),
469 got: "static".to_string(),
472 return FileDoesntMatch;
474 info!("lib candidate: {}", path.display());
476 let hash_str = hash.to_string();
477 let slot = candidates.entry(hash_str)
478 .or_insert_with(|| (FxHashMap(), FxHashMap()));
479 let (ref mut rlibs, ref mut dylibs) = *slot;
480 fs::canonicalize(path)
483 rlibs.insert(p, kind);
485 dylibs.insert(p, kind);
489 .unwrap_or(FileDoesntMatch)
491 self.rejected_via_kind.extend(staticlibs);
493 // We have now collected all known libraries into a set of candidates
494 // keyed of the filename hash listed. For each filename, we also have a
495 // list of rlibs/dylibs that apply. Here, we map each of these lists
496 // (per hash), to a Library candidate for returning.
498 // A Library candidate is created if the metadata for the set of
499 // libraries corresponds to the crate id and hash criteria that this
500 // search is being performed for.
501 let mut libraries = FxHashMap();
502 for (_hash, (rlibs, dylibs)) in candidates {
504 let rlib = self.extract_one(rlibs, CrateFlavor::Rlib, &mut slot);
505 let dylib = self.extract_one(dylibs, CrateFlavor::Dylib, &mut slot);
506 if let Some((h, m)) = slot {
516 // Having now translated all relevant found hashes into libraries, see
517 // what we've got and figure out if we found multiple candidates for
519 match libraries.len() {
521 1 => Some(libraries.into_iter().next().unwrap().1),
523 let mut err = struct_span_err!(self.sess,
526 "multiple matching crates for `{}`",
528 err.note("candidates:");
529 for (_, lib) in libraries {
530 if let Some((ref p, _)) = lib.dylib {
531 err.note(&format!("path: {}", p.display()));
533 if let Some((ref p, _)) = lib.rlib {
534 err.note(&format!("path: {}", p.display()));
536 note_crate_name(&mut err, &lib.metadata.get_root().name);
544 // Attempts to extract *one* library from the set `m`. If the set has no
545 // elements, `None` is returned. If the set has more than one element, then
546 // the errors and notes are emitted about the set of libraries.
548 // With only one library in the set, this function will extract it, and then
549 // read the metadata from it if `*slot` is `None`. If the metadata couldn't
550 // be read, it is assumed that the file isn't a valid rust library (no
551 // errors are emitted).
552 fn extract_one(&mut self,
553 m: FxHashMap<PathBuf, PathKind>,
555 slot: &mut Option<(Svh, MetadataBlob)>)
556 -> Option<(PathBuf, PathKind)> {
557 let mut ret: Option<(PathBuf, PathKind)> = None;
561 // FIXME(#10786): for an optimization, we only read one of the
562 // libraries' metadata sections. In theory we should
563 // read both, but reading dylib metadata is quite
567 } else if m.len() == 1 {
568 return Some(m.into_iter().next().unwrap());
572 let mut err: Option<DiagnosticBuilder> = None;
573 for (lib, kind) in m {
574 info!("{} reading metadata from: {}", flavor, lib.display());
575 let (hash, metadata) = match get_metadata_section(self.target, flavor, &lib) {
577 if let Some(h) = self.crate_matches(&blob, &lib) {
580 info!("metadata mismatch");
585 info!("no metadata found: {}", err);
589 // If we see multiple hashes, emit an error about duplicate candidates.
590 if slot.as_ref().map_or(false, |s| s.0 != hash) {
591 let mut e = struct_span_err!(self.sess,
594 "multiple {} candidates for `{}` found",
597 e.span_note(self.span,
598 &format!(r"candidate #1: {}",
603 if let Some(ref mut e) = err {
612 err.as_mut().unwrap().span_note(self.span,
613 &format!(r"candidate #{}: {}",
618 *slot = Some((hash, metadata));
619 ret = Some((lib, kind));
630 fn crate_matches(&mut self, metadata: &MetadataBlob, libpath: &Path) -> Option<Svh> {
631 let root = metadata.get_root();
632 if let Some(is_proc_macro) = self.is_proc_macro {
633 if root.macro_derive_registrar.is_some() != is_proc_macro {
638 let rustc_version = rustc_version();
639 if root.rustc_version != rustc_version {
640 info!("Rejecting via version: expected {} got {}",
643 self.rejected_via_version.push(CrateMismatch {
644 path: libpath.to_path_buf(),
645 got: root.rustc_version,
650 if self.should_match_name {
651 if self.crate_name != root.name {
652 info!("Rejecting via crate name");
657 if root.triple != self.triple {
658 info!("Rejecting via crate triple: expected {} got {}",
661 self.rejected_via_triple.push(CrateMismatch {
662 path: libpath.to_path_buf(),
668 if let Some(myhash) = self.hash {
669 if *myhash != root.hash {
670 info!("Rejecting via hash: expected {} got {}", *myhash, root.hash);
671 self.rejected_via_hash.push(CrateMismatch {
672 path: libpath.to_path_buf(),
673 got: myhash.to_string(),
683 // Returns the corresponding (prefix, suffix) that files need to have for
685 fn dylibname(&self) -> (String, String) {
686 let t = &self.target;
687 (t.options.dll_prefix.clone(), t.options.dll_suffix.clone())
690 // Returns the corresponding (prefix, suffix) that files need to have for
692 fn staticlibname(&self) -> (String, String) {
693 let t = &self.target;
694 (t.options.staticlib_prefix.clone(), t.options.staticlib_suffix.clone())
697 fn find_commandline_library<'b, LOCS>(&mut self, locs: LOCS) -> Option<Library>
698 where LOCS: Iterator<Item = &'b String>
700 // First, filter out all libraries that look suspicious. We only accept
701 // files which actually exist that have the correct naming scheme for
703 let sess = self.sess;
704 let dylibname = self.dylibname();
705 let mut rlibs = FxHashMap();
706 let mut dylibs = FxHashMap();
708 let locs = locs.map(|l| PathBuf::from(l)).filter(|loc| {
710 sess.err(&format!("extern location for {} does not exist: {}",
715 let file = match loc.file_name().and_then(|s| s.to_str()) {
718 sess.err(&format!("extern location for {} is not a file: {}",
724 if file.starts_with("lib") && file.ends_with(".rlib") {
727 let (ref prefix, ref suffix) = dylibname;
728 if file.starts_with(&prefix[..]) && file.ends_with(&suffix[..]) {
732 sess.struct_err(&format!("extern location for {} is of an unknown type: {}",
735 .help(&format!("file name should be lib*.rlib or {}*.{}",
742 // Now that we have an iterator of good candidates, make sure
743 // there's at most one rlib and at most one dylib.
745 if loc.file_name().unwrap().to_str().unwrap().ends_with(".rlib") {
746 rlibs.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag);
748 dylibs.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag);
753 // Extract the rlib/dylib pair.
755 let rlib = self.extract_one(rlibs, CrateFlavor::Rlib, &mut slot);
756 let dylib = self.extract_one(dylibs, CrateFlavor::Dylib, &mut slot);
758 if rlib.is_none() && dylib.is_none() {
762 Some((_, metadata)) => {
774 pub fn note_crate_name(err: &mut DiagnosticBuilder, name: &str) {
775 err.note(&format!("crate name: {}", name));
778 impl ArchiveMetadata {
779 fn new(ar: ArchiveRO) -> Option<ArchiveMetadata> {
781 let section = ar.iter()
782 .filter_map(|s| s.ok())
783 .find(|sect| sect.name() == Some(METADATA_FILENAME));
785 Some(s) => s.data() as *const [u8],
787 debug!("didn't find '{}' in the archive", METADATA_FILENAME);
793 Some(ArchiveMetadata {
799 pub fn as_slice<'a>(&'a self) -> &'a [u8] {
800 unsafe { &*self.data }
804 fn verify_decompressed_encoding_version(blob: &MetadataBlob,
806 -> Result<(), String> {
807 if !blob.is_compatible() {
808 Err((format!("incompatible metadata version found: '{}'",
809 filename.display())))
815 // Just a small wrapper to time how long reading metadata takes.
816 fn get_metadata_section(target: &Target,
819 -> Result<MetadataBlob, String> {
820 let start = Instant::now();
821 let ret = get_metadata_section_imp(target, flavor, filename);
822 info!("reading {:?} => {:?}",
823 filename.file_name().unwrap(),
828 fn get_metadata_section_imp(target: &Target,
831 -> Result<MetadataBlob, String> {
832 if !filename.exists() {
833 return Err(format!("no such file: '{}'", filename.display()));
835 if flavor == CrateFlavor::Rlib {
836 // Use ArchiveRO for speed here, it's backed by LLVM and uses mmap
837 // internally to read the file. We also avoid even using a memcpy by
838 // just keeping the archive along while the metadata is in use.
839 let archive = match ArchiveRO::open(filename) {
842 debug!("llvm didn't like `{}`", filename.display());
843 return Err(format!("failed to read rlib metadata: '{}'", filename.display()));
846 return match ArchiveMetadata::new(archive).map(|ar| MetadataBlob::Archive(ar)) {
847 None => Err(format!("failed to read rlib metadata: '{}'", filename.display())),
849 verify_decompressed_encoding_version(&blob, filename)?;
855 let buf = common::path2cstr(filename);
856 let mb = llvm::LLVMRustCreateMemoryBufferWithContentsOfFile(buf.as_ptr());
857 if mb as isize == 0 {
858 return Err(format!("error reading library: '{}'", filename.display()));
860 let of = match ObjectFile::new(mb) {
863 return Err((format!("provided path not an object file: '{}'", filename.display())))
866 let si = mk_section_iter(of.llof);
867 while llvm::LLVMIsSectionIteratorAtEnd(of.llof, si.llsi) == False {
868 let mut name_buf = ptr::null();
869 let name_len = llvm::LLVMRustGetSectionName(si.llsi, &mut name_buf);
870 let name = slice::from_raw_parts(name_buf as *const u8, name_len as usize).to_vec();
871 let name = String::from_utf8(name).unwrap();
872 debug!("get_metadata_section: name {}", name);
873 if read_meta_section_name(target) == name {
874 let cbuf = llvm::LLVMGetSectionContents(si.llsi);
875 let csz = llvm::LLVMGetSectionSize(si.llsi) as usize;
876 let cvbuf: *const u8 = cbuf as *const u8;
877 let vlen = METADATA_HEADER.len();
878 debug!("checking {} bytes of metadata-version stamp", vlen);
879 let minsz = cmp::min(vlen, csz);
880 let buf0 = slice::from_raw_parts(cvbuf, minsz);
881 let version_ok = buf0 == METADATA_HEADER;
883 return Err((format!("incompatible metadata version found: '{}'",
884 filename.display())));
887 let cvbuf1 = cvbuf.offset(vlen as isize);
888 debug!("inflating {} bytes of compressed metadata", csz - vlen);
889 let bytes = slice::from_raw_parts(cvbuf1, csz - vlen);
890 match flate::inflate_bytes(bytes) {
892 let blob = MetadataBlob::Inflated(inflated);
893 verify_decompressed_encoding_version(&blob, filename)?;
899 llvm::LLVMMoveToNextSection(si.llsi);
901 Err(format!("metadata not found: '{}'", filename.display()))
905 pub fn meta_section_name(target: &Target) -> &'static str {
908 // When using link.exe it was seen that the section name `.note.rustc`
909 // was getting shortened to `.note.ru`, and according to the PE and COFF
912 // > Executable images do not use a string table and do not support
913 // > section names longer than 8 characters
915 // https://msdn.microsoft.com/en-us/library/windows/hardware/gg463119.aspx
917 // As a result, we choose a slightly shorter name! As to why
918 // `.note.rustc` works on MinGW, that's another good question...
920 if target.options.is_like_osx {
927 pub fn read_meta_section_name(_target: &Target) -> &'static str {
931 // A diagnostic function for dumping crate metadata to an output stream
932 pub fn list_file_metadata(target: &Target, path: &Path, out: &mut io::Write) -> io::Result<()> {
933 let filename = path.file_name().unwrap().to_str().unwrap();
934 let flavor = if filename.ends_with(".rlib") {
939 match get_metadata_section(target, flavor, path) {
940 Ok(metadata) => metadata.list_crate_metadata(out),
941 Err(msg) => write!(out, "{}\n", msg),