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::loader or metadata::creader for all the juicy details!
215 use cstore::{MetadataBlob, MetadataVec, MetadataArchive};
219 use rustc::back::svh::Svh;
220 use rustc::session::Session;
221 use rustc::session::filesearch::{FileSearch, FileMatches, FileDoesntMatch};
222 use rustc::session::search_paths::PathKind;
223 use rustc::util::common;
225 use rustc_llvm as llvm;
226 use rustc_llvm::{False, ObjectFile, mk_section_iter};
227 use rustc_llvm::archive_ro::ArchiveRO;
228 use syntax::codemap::Span;
229 use syntax::errors::DiagnosticBuilder;
230 use rustc_back::target::Target;
233 use std::collections::HashMap;
235 use std::io::prelude::*;
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 should_match_name: bool,
267 pub dylib: Option<(PathBuf, PathKind)>,
268 pub rlib: Option<(PathBuf, PathKind)>,
269 pub metadata: MetadataBlob,
272 pub struct ArchiveMetadata {
274 // points into self._archive
278 pub struct CratePaths {
280 pub dylib: Option<PathBuf>,
281 pub rlib: Option<PathBuf>
284 pub const METADATA_FILENAME: &'static str = "rust.metadata.bin";
287 fn paths(&self) -> Vec<PathBuf> {
288 match (&self.dylib, &self.rlib) {
289 (&None, &None) => vec!(),
290 (&Some(ref p), &None) |
291 (&None, &Some(ref p)) => vec!(p.clone()),
292 (&Some(ref p1), &Some(ref p2)) => vec!(p1.clone(), p2.clone()),
297 impl<'a> Context<'a> {
298 pub fn maybe_load_library_crate(&mut self) -> Option<Library> {
299 self.find_library_crate()
302 pub fn load_library_crate(&mut self) -> Library {
303 match self.find_library_crate() {
306 self.report_load_errs();
312 pub fn report_load_errs(&mut self) {
313 let add = match self.root {
314 &None => String::new(),
315 &Some(ref r) => format!(" which `{}` depends on",
318 let mut err = if !self.rejected_via_hash.is_empty() {
319 struct_span_err!(self.sess, self.span, E0460,
320 "found possibly newer version of crate `{}`{}",
322 } else if !self.rejected_via_triple.is_empty() {
323 struct_span_err!(self.sess, self.span, E0461,
324 "couldn't find crate `{}` with expected target triple {}{}",
325 self.ident, self.triple, add)
326 } else if !self.rejected_via_kind.is_empty() {
327 struct_span_err!(self.sess, self.span, E0462,
328 "found staticlib `{}` instead of rlib or dylib{}",
331 struct_span_err!(self.sess, self.span, E0463,
332 "can't find crate for `{}`{}",
336 if !self.rejected_via_triple.is_empty() {
337 let mismatches = self.rejected_via_triple.iter();
338 for (i, &CrateMismatch{ ref path, ref got }) in mismatches.enumerate() {
339 err.fileline_note(self.span,
340 &format!("crate `{}`, path #{}, triple {}: {}",
341 self.ident, i+1, got, path.display()));
344 if !self.rejected_via_hash.is_empty() {
345 err.span_note(self.span, "perhaps this crate needs \
347 let mismatches = self.rejected_via_hash.iter();
348 for (i, &CrateMismatch{ ref path, .. }) in mismatches.enumerate() {
349 err.fileline_note(self.span,
350 &format!("crate `{}` path #{}: {}",
351 self.ident, i+1, path.display()));
356 for (i, path) in r.paths().iter().enumerate() {
357 err.fileline_note(self.span,
358 &format!("crate `{}` path #{}: {}",
359 r.ident, i+1, path.display()));
364 if !self.rejected_via_kind.is_empty() {
365 err.fileline_help(self.span, "please recompile this crate using \
367 let mismatches = self.rejected_via_kind.iter();
368 for (i, &CrateMismatch { ref path, .. }) in mismatches.enumerate() {
369 err.fileline_note(self.span,
370 &format!("crate `{}` path #{}: {}",
371 self.ident, i+1, path.display()));
376 self.sess.abort_if_errors();
379 fn find_library_crate(&mut self) -> Option<Library> {
380 // If an SVH is specified, then this is a transitive dependency that
381 // must be loaded via -L plus some filtering.
382 if self.hash.is_none() {
383 self.should_match_name = false;
384 if let Some(s) = self.sess.opts.externs.get(self.crate_name) {
385 return self.find_commandline_library(s);
387 self.should_match_name = true;
390 let dypair = self.dylibname();
391 let staticpair = self.staticlibname();
393 // want: crate_name.dir_part() + prefix + crate_name.file_part + "-"
394 let dylib_prefix = format!("{}{}", dypair.0, self.crate_name);
395 let rlib_prefix = format!("lib{}", self.crate_name);
396 let staticlib_prefix = format!("{}{}", staticpair.0, self.crate_name);
398 let mut candidates = HashMap::new();
399 let mut staticlibs = vec!();
401 // First, find all possible candidate rlibs and dylibs purely based on
402 // the name of the files themselves. We're trying to match against an
403 // exact crate name and a possibly an exact hash.
405 // During this step, we can filter all found libraries based on the
406 // name and id found in the crate id (we ignore the path portion for
407 // filename matching), as well as the exact hash (if specified). If we
408 // end up having many candidates, we must look at the metadata to
409 // perform exact matches against hashes/crate ids. Note that opening up
410 // the metadata is where we do an exact match against the full contents
411 // of the crate id (path/name/id).
413 // The goal of this step is to look at as little metadata as possible.
414 self.filesearch.search(|path, kind| {
415 let file = match path.file_name().and_then(|s| s.to_str()) {
416 None => return FileDoesntMatch,
419 let (hash, rlib) = if file.starts_with(&rlib_prefix[..]) &&
420 file.ends_with(".rlib") {
421 (&file[(rlib_prefix.len()) .. (file.len() - ".rlib".len())],
423 } else if file.starts_with(&dylib_prefix) &&
424 file.ends_with(&dypair.1) {
425 (&file[(dylib_prefix.len()) .. (file.len() - dypair.1.len())],
428 if file.starts_with(&staticlib_prefix[..]) &&
429 file.ends_with(&staticpair.1) {
430 staticlibs.push(CrateMismatch {
431 path: path.to_path_buf(),
432 got: "static".to_string()
435 return FileDoesntMatch
437 info!("lib candidate: {}", path.display());
439 let hash_str = hash.to_string();
440 let slot = candidates.entry(hash_str)
441 .or_insert_with(|| (HashMap::new(), HashMap::new()));
442 let (ref mut rlibs, ref mut dylibs) = *slot;
443 fs::canonicalize(path).map(|p| {
445 rlibs.insert(p, kind);
447 dylibs.insert(p, kind);
450 }).unwrap_or(FileDoesntMatch)
452 self.rejected_via_kind.extend(staticlibs);
454 // We have now collected all known libraries into a set of candidates
455 // keyed of the filename hash listed. For each filename, we also have a
456 // list of rlibs/dylibs that apply. Here, we map each of these lists
457 // (per hash), to a Library candidate for returning.
459 // A Library candidate is created if the metadata for the set of
460 // libraries corresponds to the crate id and hash criteria that this
461 // search is being performed for.
462 let mut libraries = Vec::new();
463 for (_hash, (rlibs, dylibs)) in candidates {
464 let mut metadata = None;
465 let rlib = self.extract_one(rlibs, "rlib", &mut metadata);
466 let dylib = self.extract_one(dylibs, "dylib", &mut metadata);
469 libraries.push(Library {
479 // Having now translated all relevant found hashes into libraries, see
480 // what we've got and figure out if we found multiple candidates for
482 match libraries.len() {
484 1 => Some(libraries.into_iter().next().unwrap()),
486 let mut err = struct_span_err!(self.sess, self.span, E0464,
487 "multiple matching crates for `{}`",
489 err.note("candidates:");
490 for lib in &libraries {
492 Some((ref p, _)) => {
493 err.note(&format!("path: {}",
499 Some((ref p, _)) => {
500 err.note(&format!("path: {}",
505 let data = lib.metadata.as_slice();
506 let name = decoder::get_crate_name(data);
507 note_crate_name(&mut err, &name);
515 // Attempts to extract *one* library from the set `m`. If the set has no
516 // elements, `None` is returned. If the set has more than one element, then
517 // the errors and notes are emitted about the set of libraries.
519 // With only one library in the set, this function will extract it, and then
520 // read the metadata from it if `*slot` is `None`. If the metadata couldn't
521 // be read, it is assumed that the file isn't a valid rust library (no
522 // errors are emitted).
523 fn extract_one(&mut self, m: HashMap<PathBuf, PathKind>, flavor: &str,
524 slot: &mut Option<MetadataBlob>) -> Option<(PathBuf, PathKind)> {
525 let mut ret = None::<(PathBuf, PathKind)>;
529 // FIXME(#10786): for an optimization, we only read one of the
530 // library's metadata sections. In theory we should
531 // read both, but reading dylib metadata is quite
535 } else if m.len() == 1 {
536 return Some(m.into_iter().next().unwrap())
540 let mut err: Option<DiagnosticBuilder> = None;
541 for (lib, kind) in m {
542 info!("{} reading metadata from: {}", flavor, lib.display());
543 let metadata = match get_metadata_section(self.target, &lib) {
545 if self.crate_matches(blob.as_slice(), &lib) {
548 info!("metadata mismatch");
553 info!("no metadata found: {}", err);
557 // If we've already found a candidate and we're not matching hashes,
558 // emit an error about duplicate candidates found. If we're matching
559 // based on a hash, however, then if we've gotten this far both
560 // candidates have the same hash, so they're not actually
561 // duplicates that we should warn about.
562 if ret.is_some() && self.hash.is_none() {
563 let mut e = struct_span_err!(self.sess, self.span, E0465,
564 "multiple {} candidates for `{}` found",
565 flavor, self.crate_name);
566 e.span_note(self.span,
567 &format!(r"candidate #1: {}",
568 ret.as_ref().unwrap().0
570 if let Some(ref mut e) = err {
579 err.as_mut().unwrap().span_note(self.span,
580 &format!(r"candidate #{}: {}", error,
584 *slot = Some(metadata);
585 ret = Some((lib, kind));
596 fn crate_matches(&mut self, crate_data: &[u8], libpath: &Path) -> bool {
597 if self.should_match_name {
598 match decoder::maybe_get_crate_name(crate_data) {
599 Some(ref name) if self.crate_name == *name => {}
600 _ => { info!("Rejecting via crate name"); return false }
603 let hash = match decoder::maybe_get_crate_hash(crate_data) {
604 Some(hash) => hash, None => {
605 info!("Rejecting via lack of crate hash");
610 let triple = match decoder::get_crate_triple(crate_data) {
611 None => { debug!("triple not present"); return false }
614 if triple != self.triple {
615 info!("Rejecting via crate triple: expected {} got {}", self.triple, triple);
616 self.rejected_via_triple.push(CrateMismatch {
617 path: libpath.to_path_buf(),
618 got: triple.to_string()
627 info!("Rejecting via hash: expected {} got {}", *myhash, hash);
628 self.rejected_via_hash.push(CrateMismatch {
629 path: libpath.to_path_buf(),
630 got: myhash.as_str().to_string()
641 // Returns the corresponding (prefix, suffix) that files need to have for
643 fn dylibname(&self) -> (String, String) {
644 let t = &self.target;
645 (t.options.dll_prefix.clone(), t.options.dll_suffix.clone())
648 // Returns the corresponding (prefix, suffix) that files need to have for
650 fn staticlibname(&self) -> (String, String) {
651 let t = &self.target;
652 (t.options.staticlib_prefix.clone(), t.options.staticlib_suffix.clone())
655 fn find_commandline_library(&mut self, locs: &[String]) -> Option<Library> {
656 // First, filter out all libraries that look suspicious. We only accept
657 // files which actually exist that have the correct naming scheme for
659 let sess = self.sess;
660 let dylibname = self.dylibname();
661 let mut rlibs = HashMap::new();
662 let mut dylibs = HashMap::new();
664 let locs = locs.iter().map(|l| PathBuf::from(l)).filter(|loc| {
666 sess.err(&format!("extern location for {} does not exist: {}",
667 self.crate_name, loc.display()));
670 let file = match loc.file_name().and_then(|s| s.to_str()) {
673 sess.err(&format!("extern location for {} is not a file: {}",
674 self.crate_name, loc.display()));
678 if file.starts_with("lib") && file.ends_with(".rlib") {
681 let (ref prefix, ref suffix) = dylibname;
682 if file.starts_with(&prefix[..]) &&
683 file.ends_with(&suffix[..]) {
687 sess.struct_err(&format!("extern location for {} is of an unknown type: {}",
688 self.crate_name, loc.display()))
689 .help(&format!("file name should be lib*.rlib or {}*.{}",
690 dylibname.0, dylibname.1))
695 // Now that we have an iterator of good candidates, make sure
696 // there's at most one rlib and at most one dylib.
698 if loc.file_name().unwrap().to_str().unwrap().ends_with(".rlib") {
699 rlibs.insert(fs::canonicalize(&loc).unwrap(),
700 PathKind::ExternFlag);
702 dylibs.insert(fs::canonicalize(&loc).unwrap(),
703 PathKind::ExternFlag);
708 // Extract the rlib/dylib pair.
709 let mut metadata = None;
710 let rlib = self.extract_one(rlibs, "rlib", &mut metadata);
711 let dylib = self.extract_one(dylibs, "dylib", &mut metadata);
713 if rlib.is_none() && dylib.is_none() { return None }
715 Some(metadata) => Some(Library {
725 pub fn note_crate_name(err: &mut DiagnosticBuilder, name: &str) {
726 err.note(&format!("crate name: {}", name));
729 impl ArchiveMetadata {
730 fn new(ar: ArchiveRO) -> Option<ArchiveMetadata> {
732 let section = ar.iter().find(|sect| {
733 sect.name() == Some(METADATA_FILENAME)
736 Some(s) => s.data() as *const [u8],
738 debug!("didn't find '{}' in the archive", METADATA_FILENAME);
744 Some(ArchiveMetadata {
750 pub fn as_slice<'a>(&'a self) -> &'a [u8] { unsafe { &*self.data } }
753 // Just a small wrapper to time how long reading metadata takes.
754 fn get_metadata_section(target: &Target, filename: &Path)
755 -> Result<MetadataBlob, String> {
756 let start = Instant::now();
757 let ret = get_metadata_section_imp(target, filename);
758 info!("reading {:?} => {:?}", filename.file_name().unwrap(),
763 fn get_metadata_section_imp(target: &Target, filename: &Path)
764 -> Result<MetadataBlob, String> {
765 if !filename.exists() {
766 return Err(format!("no such file: '{}'", filename.display()));
768 if filename.file_name().unwrap().to_str().unwrap().ends_with(".rlib") {
769 // Use ArchiveRO for speed here, it's backed by LLVM and uses mmap
770 // internally to read the file. We also avoid even using a memcpy by
771 // just keeping the archive along while the metadata is in use.
772 let archive = match ArchiveRO::open(filename) {
775 debug!("llvm didn't like `{}`", filename.display());
776 return Err(format!("failed to read rlib metadata: '{}'",
777 filename.display()));
780 return match ArchiveMetadata::new(archive).map(|ar| MetadataArchive(ar)) {
781 None => Err(format!("failed to read rlib metadata: '{}'",
782 filename.display())),
783 Some(blob) => Ok(blob)
787 let buf = common::path2cstr(filename);
788 let mb = llvm::LLVMRustCreateMemoryBufferWithContentsOfFile(buf.as_ptr());
789 if mb as isize == 0 {
790 return Err(format!("error reading library: '{}'",
793 let of = match ObjectFile::new(mb) {
796 return Err((format!("provided path not an object file: '{}'",
797 filename.display())))
800 let si = mk_section_iter(of.llof);
801 while llvm::LLVMIsSectionIteratorAtEnd(of.llof, si.llsi) == False {
802 let mut name_buf = ptr::null();
803 let name_len = llvm::LLVMRustGetSectionName(si.llsi, &mut name_buf);
804 let name = slice::from_raw_parts(name_buf as *const u8,
805 name_len as usize).to_vec();
806 let name = String::from_utf8(name).unwrap();
807 debug!("get_metadata_section: name {}", name);
808 if read_meta_section_name(target) == name {
809 let cbuf = llvm::LLVMGetSectionContents(si.llsi);
810 let csz = llvm::LLVMGetSectionSize(si.llsi) as usize;
811 let cvbuf: *const u8 = cbuf as *const u8;
812 let vlen = encoder::metadata_encoding_version.len();
813 debug!("checking {} bytes of metadata-version stamp",
815 let minsz = cmp::min(vlen, csz);
816 let buf0 = slice::from_raw_parts(cvbuf, minsz);
817 let version_ok = buf0 == encoder::metadata_encoding_version;
819 return Err((format!("incompatible metadata version found: '{}'",
820 filename.display())));
823 let cvbuf1 = cvbuf.offset(vlen as isize);
824 debug!("inflating {} bytes of compressed metadata",
826 let bytes = slice::from_raw_parts(cvbuf1, csz - vlen);
827 match flate::inflate_bytes(bytes) {
828 Ok(inflated) => return Ok(MetadataVec(inflated)),
832 llvm::LLVMMoveToNextSection(si.llsi);
834 Err(format!("metadata not found: '{}'", filename.display()))
838 pub fn meta_section_name(target: &Target) -> &'static str {
839 if target.options.is_like_osx {
840 "__DATA,__note.rustc"
841 } else if target.options.is_like_msvc {
842 // When using link.exe it was seen that the section name `.note.rustc`
843 // was getting shortened to `.note.ru`, and according to the PE and COFF
846 // > Executable images do not use a string table and do not support
847 // > section names longer than 8 characters
849 // https://msdn.microsoft.com/en-us/library/windows/hardware/gg463119.aspx
851 // As a result, we choose a slightly shorter name! As to why
852 // `.note.rustc` works on MinGW, that's another good question...
859 pub fn read_meta_section_name(target: &Target) -> &'static str {
860 if target.options.is_like_osx {
862 } else if target.options.is_like_msvc {
869 // A diagnostic function for dumping crate metadata to an output stream
870 pub fn list_file_metadata(target: &Target, path: &Path,
871 out: &mut io::Write) -> io::Result<()> {
872 match get_metadata_section(target, path) {
873 Ok(bytes) => decoder::list_crate_metadata(bytes.as_slice(), out),
875 write!(out, "{}\n", msg)