| //! Finds crate binaries and loads their metadata |
| //! |
| //! Might I be the first to welcome you to a world of platform differences, |
| //! version requirements, dependency graphs, conflicting desires, and fun! This |
| //! is the major guts (along with metadata::creader) of the compiler for loading |
| //! crates and resolving dependencies. Let's take a tour! |
| //! |
| //! # The problem |
| //! |
| //! Each invocation of the compiler is immediately concerned with one primary |
| //! problem, to connect a set of crates to resolved crates on the filesystem. |
| //! Concretely speaking, the compiler follows roughly these steps to get here: |
| //! |
| //! 1. Discover a set of `extern crate` statements. |
| //! 2. Transform these directives into crate names. If the directive does not |
| //! have an explicit name, then the identifier is the name. |
| //! 3. For each of these crate names, find a corresponding crate on the |
| //! filesystem. |
| //! |
| //! Sounds easy, right? Let's walk into some of the nuances. |
| //! |
| //! ## Transitive Dependencies |
| //! |
| //! Let's say we've got three crates: A, B, and C. A depends on B, and B depends |
| //! on C. When we're compiling A, we primarily need to find and locate B, but we |
| //! also end up needing to find and locate C as well. |
| //! |
| //! The reason for this is that any of B's types could be composed of C's types, |
| //! any function in B could return a type from C, etc. To be able to guarantee |
| //! that we can always type-check/translate any function, we have to have |
| //! complete knowledge of the whole ecosystem, not just our immediate |
| //! dependencies. |
| //! |
| //! So now as part of the "find a corresponding crate on the filesystem" step |
| //! above, this involves also finding all crates for *all upstream |
| //! dependencies*. This includes all dependencies transitively. |
| //! |
| //! ## Rlibs and Dylibs |
| //! |
| //! The compiler has two forms of intermediate dependencies. These are dubbed |
| //! rlibs and dylibs for the static and dynamic variants, respectively. An rlib |
| //! is a rustc-defined file format (currently just an ar archive) while a dylib |
| //! is a platform-defined dynamic library. Each library has a metadata somewhere |
| //! inside of it. |
| //! |
| //! A third kind of dependency is an rmeta file. These are metadata files and do |
| //! not contain any code, etc. To a first approximation, these are treated in the |
| //! same way as rlibs. Where there is both an rlib and an rmeta file, the rlib |
| //! gets priority (even if the rmeta file is newer). An rmeta file is only |
| //! useful for checking a downstream crate, attempting to link one will cause an |
| //! error. |
| //! |
| //! When translating a crate name to a crate on the filesystem, we all of a |
| //! sudden need to take into account both rlibs and dylibs! Linkage later on may |
| //! use either one of these files, as each has their pros/cons. The job of crate |
| //! loading is to discover what's possible by finding all candidates. |
| //! |
| //! Most parts of this loading systems keep the dylib/rlib as just separate |
| //! variables. |
| //! |
| //! ## Where to look? |
| //! |
| //! We can't exactly scan your whole hard drive when looking for dependencies, |
| //! so we need to places to look. Currently the compiler will implicitly add the |
| //! target lib search path ($prefix/lib/rustlib/$target/lib) to any compilation, |
| //! and otherwise all -L flags are added to the search paths. |
| //! |
| //! ## What criterion to select on? |
| //! |
| //! This a pretty tricky area of loading crates. Given a file, how do we know |
| //! whether it's the right crate? Currently, the rules look along these lines: |
| //! |
| //! 1. Does the filename match an rlib/dylib pattern? That is to say, does the |
| //! filename have the right prefix/suffix? |
| //! 2. Does the filename have the right prefix for the crate name being queried? |
| //! This is filtering for files like `libfoo*.rlib` and such. If the crate |
| //! we're looking for was originally compiled with -C extra-filename, the |
| //! extra filename will be included in this prefix to reduce reading |
| //! metadata from crates that would otherwise share our prefix. |
| //! 3. Is the file an actual rust library? This is done by loading the metadata |
| //! from the library and making sure it's actually there. |
| //! 4. Does the name in the metadata agree with the name of the library? |
| //! 5. Does the target in the metadata agree with the current target? |
| //! 6. Does the SVH match? (more on this later) |
| //! |
| //! If the file answers `yes` to all these questions, then the file is |
| //! considered as being *candidate* for being accepted. It is illegal to have |
| //! more than two candidates as the compiler has no method by which to resolve |
| //! this conflict. Additionally, rlib/dylib candidates are considered |
| //! separately. |
| //! |
| //! After all this has happened, we have 1 or two files as candidates. These |
| //! represent the rlib/dylib file found for a library, and they're returned as |
| //! being found. |
| //! |
| //! ### What about versions? |
| //! |
| //! A lot of effort has been put forth to remove versioning from the compiler. |
| //! There have been forays in the past to have versioning baked in, but it was |
| //! largely always deemed insufficient to the point that it was recognized that |
| //! it's probably something the compiler shouldn't do anyway due to its |
| //! complicated nature and the state of the half-baked solutions. |
| //! |
| //! With a departure from versioning, the primary criterion for loading crates |
| //! is just the name of a crate. If we stopped here, it would imply that you |
| //! could never link two crates of the same name from different sources |
| //! together, which is clearly a bad state to be in. |
| //! |
| //! To resolve this problem, we come to the next section! |
| //! |
| //! # Expert Mode |
| //! |
| //! A number of flags have been added to the compiler to solve the "version |
| //! problem" in the previous section, as well as generally enabling more |
| //! powerful usage of the crate loading system of the compiler. The goal of |
| //! these flags and options are to enable third-party tools to drive the |
| //! compiler with prior knowledge about how the world should look. |
| //! |
| //! ## The `--extern` flag |
| //! |
| //! The compiler accepts a flag of this form a number of times: |
| //! |
| //! ```text |
| //! --extern crate-name=path/to/the/crate.rlib |
| //! ``` |
| //! |
| //! This flag is basically the following letter to the compiler: |
| //! |
| //! > Dear rustc, |
| //! > |
| //! > When you are attempting to load the immediate dependency `crate-name`, I |
| //! > would like you to assume that the library is located at |
| //! > `path/to/the/crate.rlib`, and look nowhere else. Also, please do not |
| //! > assume that the path I specified has the name `crate-name`. |
| //! |
| //! This flag basically overrides most matching logic except for validating that |
| //! the file is indeed a rust library. The same `crate-name` can be specified |
| //! twice to specify the rlib/dylib pair. |
| //! |
| //! ## Enabling "multiple versions" |
| //! |
| //! This basically boils down to the ability to specify arbitrary packages to |
| //! the compiler. For example, if crate A wanted to use Bv1 and Bv2, then it |
| //! would look something like: |
| //! |
| //! ```compile_fail,E0463 |
| //! extern crate b1; |
| //! extern crate b2; |
| //! |
| //! fn main() {} |
| //! ``` |
| //! |
| //! and the compiler would be invoked as: |
| //! |
| //! ```text |
| //! rustc a.rs --extern b1=path/to/libb1.rlib --extern b2=path/to/libb2.rlib |
| //! ``` |
| //! |
| //! In this scenario there are two crates named `b` and the compiler must be |
| //! manually driven to be informed where each crate is. |
| //! |
| //! ## Frobbing symbols |
| //! |
| //! One of the immediate problems with linking the same library together twice |
| //! in the same problem is dealing with duplicate symbols. The primary way to |
| //! deal with this in rustc is to add hashes to the end of each symbol. |
| //! |
| //! In order to force hashes to change between versions of a library, if |
| //! desired, the compiler exposes an option `-C metadata=foo`, which is used to |
| //! initially seed each symbol hash. The string `foo` is prepended to each |
| //! string-to-hash to ensure that symbols change over time. |
| //! |
| //! ## Loading transitive dependencies |
| //! |
| //! Dealing with same-named-but-distinct crates is not just a local problem, but |
| //! one that also needs to be dealt with for transitive dependencies. Note that |
| //! in the letter above `--extern` flags only apply to the *local* set of |
| //! dependencies, not the upstream transitive dependencies. Consider this |
| //! dependency graph: |
| //! |
| //! ```text |
| //! A.1 A.2 |
| //! | | |
| //! | | |
| //! B C |
| //! \ / |
| //! \ / |
| //! D |
| //! ``` |
| //! |
| //! In this scenario, when we compile `D`, we need to be able to distinctly |
| //! resolve `A.1` and `A.2`, but an `--extern` flag cannot apply to these |
| //! transitive dependencies. |
| //! |
| //! Note that the key idea here is that `B` and `C` are both *already compiled*. |
| //! That is, they have already resolved their dependencies. Due to unrelated |
| //! technical reasons, when a library is compiled, it is only compatible with |
| //! the *exact same* version of the upstream libraries it was compiled against. |
| //! We use the "Strict Version Hash" to identify the exact copy of an upstream |
| //! library. |
| //! |
| //! With this knowledge, we know that `B` and `C` will depend on `A` with |
| //! different SVH values, so we crawl the normal `-L` paths looking for |
| //! `liba*.rlib` and filter based on the contained SVH. |
| //! |
| //! In the end, this ends up not needing `--extern` to specify upstream |
| //! transitive dependencies. |
| //! |
| //! # Wrapping up |
| //! |
| //! That's the general overview of loading crates in the compiler, but it's by |
| //! no means all of the necessary details. Take a look at the rest of |
| //! metadata::locator or metadata::creader for all the juicy details! |
| |
| use crate::creader::Library; |
| use crate::rmeta::{rustc_version, MetadataBlob, METADATA_HEADER}; |
| |
| use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
| use rustc_data_structures::svh::Svh; |
| use rustc_data_structures::sync::MetadataRef; |
| use rustc_errors::{struct_span_err, DiagnosticBuilder}; |
| use rustc_middle::middle::cstore::{CrateSource, MetadataLoader}; |
| use rustc_session::config::{self, CrateType}; |
| use rustc_session::filesearch::{FileDoesntMatch, FileMatches, FileSearch}; |
| use rustc_session::search_paths::PathKind; |
| use rustc_session::{CrateDisambiguator, Session}; |
| use rustc_span::symbol::{sym, Symbol}; |
| use rustc_span::Span; |
| use rustc_target::spec::{Target, TargetTriple}; |
| |
| use std::cmp; |
| use std::fmt; |
| use std::fs; |
| use std::io::{self, Read}; |
| use std::ops::Deref; |
| use std::path::{Path, PathBuf}; |
| use std::time::Instant; |
| |
| use flate2::read::DeflateDecoder; |
| |
| use rustc_data_structures::owning_ref::OwningRef; |
| |
| use log::{debug, info, warn}; |
| |
| #[derive(Clone)] |
| struct CrateMismatch { |
| path: PathBuf, |
| got: String, |
| } |
| |
| #[derive(Clone)] |
| crate struct CrateLocator<'a> { |
| // Immutable per-session configuration. |
| sess: &'a Session, |
| metadata_loader: &'a dyn MetadataLoader, |
| |
| // Immutable per-search configuration. |
| crate_name: Symbol, |
| exact_paths: Vec<PathBuf>, |
| pub hash: Option<Svh>, |
| pub host_hash: Option<Svh>, |
| extra_filename: Option<&'a str>, |
| pub target: &'a Target, |
| pub triple: TargetTriple, |
| pub filesearch: FileSearch<'a>, |
| span: Span, |
| root: Option<&'a CratePaths>, |
| pub is_proc_macro: Option<bool>, |
| |
| // Mutable in-progress state or output. |
| rejected_via_hash: Vec<CrateMismatch>, |
| rejected_via_triple: Vec<CrateMismatch>, |
| rejected_via_kind: Vec<CrateMismatch>, |
| rejected_via_version: Vec<CrateMismatch>, |
| rejected_via_filename: Vec<CrateMismatch>, |
| } |
| |
| crate struct CratePaths { |
| name: Symbol, |
| source: CrateSource, |
| } |
| |
| impl CratePaths { |
| crate fn new(name: Symbol, source: CrateSource) -> CratePaths { |
| CratePaths { name, source } |
| } |
| } |
| |
| #[derive(Copy, Clone, PartialEq)] |
| enum CrateFlavor { |
| Rlib, |
| Rmeta, |
| Dylib, |
| } |
| |
| impl fmt::Display for CrateFlavor { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.write_str(match *self { |
| CrateFlavor::Rlib => "rlib", |
| CrateFlavor::Rmeta => "rmeta", |
| CrateFlavor::Dylib => "dylib", |
| }) |
| } |
| } |
| |
| impl<'a> CrateLocator<'a> { |
| crate fn new( |
| sess: &'a Session, |
| metadata_loader: &'a dyn MetadataLoader, |
| crate_name: Symbol, |
| hash: Option<Svh>, |
| host_hash: Option<Svh>, |
| extra_filename: Option<&'a str>, |
| is_host: bool, |
| path_kind: PathKind, |
| span: Span, |
| root: Option<&'a CratePaths>, |
| is_proc_macro: Option<bool>, |
| ) -> CrateLocator<'a> { |
| CrateLocator { |
| sess, |
| metadata_loader, |
| crate_name, |
| exact_paths: if hash.is_none() { |
| sess.opts |
| .externs |
| .get(&crate_name.as_str()) |
| .into_iter() |
| .filter_map(|entry| entry.files()) |
| .flatten() |
| .map(PathBuf::from) |
| .collect() |
| } else { |
| // SVH being specified means this is a transitive dependency, |
| // so `--extern` options do not apply. |
| Vec::new() |
| }, |
| hash, |
| host_hash, |
| extra_filename, |
| target: if is_host { &sess.host } else { &sess.target.target }, |
| triple: if is_host { |
| TargetTriple::from_triple(config::host_triple()) |
| } else { |
| sess.opts.target_triple.clone() |
| }, |
| filesearch: if is_host { |
| sess.host_filesearch(path_kind) |
| } else { |
| sess.target_filesearch(path_kind) |
| }, |
| span, |
| root, |
| is_proc_macro, |
| rejected_via_hash: Vec::new(), |
| rejected_via_triple: Vec::new(), |
| rejected_via_kind: Vec::new(), |
| rejected_via_version: Vec::new(), |
| rejected_via_filename: Vec::new(), |
| } |
| } |
| |
| crate fn reset(&mut self) { |
| self.rejected_via_hash.clear(); |
| self.rejected_via_triple.clear(); |
| self.rejected_via_kind.clear(); |
| self.rejected_via_version.clear(); |
| self.rejected_via_filename.clear(); |
| } |
| |
| crate fn maybe_load_library_crate(&mut self) -> Option<Library> { |
| if !self.exact_paths.is_empty() { |
| return self.find_commandline_library(); |
| } |
| let mut seen_paths = FxHashSet::default(); |
| match self.extra_filename { |
| Some(s) => self |
| .find_library_crate(s, &mut seen_paths) |
| .or_else(|| self.find_library_crate("", &mut seen_paths)), |
| None => self.find_library_crate("", &mut seen_paths), |
| } |
| } |
| |
| crate fn report_errs(self) -> ! { |
| let add = match self.root { |
| None => String::new(), |
| Some(r) => format!(" which `{}` depends on", r.name), |
| }; |
| let mut msg = "the following crate versions were found:".to_string(); |
| let mut err = if !self.rejected_via_hash.is_empty() { |
| let mut err = struct_span_err!( |
| self.sess, |
| self.span, |
| E0460, |
| "found possibly newer version of crate `{}`{}", |
| self.crate_name, |
| add |
| ); |
| err.note("perhaps that crate needs to be recompiled?"); |
| let mismatches = self.rejected_via_hash.iter(); |
| for &CrateMismatch { ref path, .. } in mismatches { |
| msg.push_str(&format!("\ncrate `{}`: {}", self.crate_name, path.display())); |
| } |
| match self.root { |
| None => {} |
| Some(r) => { |
| for path in r.source.paths() { |
| msg.push_str(&format!("\ncrate `{}`: {}", r.name, path.display())); |
| } |
| } |
| } |
| err.note(&msg); |
| err |
| } else if !self.rejected_via_triple.is_empty() { |
| let mut err = struct_span_err!( |
| self.sess, |
| self.span, |
| E0461, |
| "couldn't find crate `{}` \ |
| with expected target triple {}{}", |
| self.crate_name, |
| self.triple, |
| add |
| ); |
| let mismatches = self.rejected_via_triple.iter(); |
| for &CrateMismatch { ref path, ref got } in mismatches { |
| msg.push_str(&format!( |
| "\ncrate `{}`, target triple {}: {}", |
| self.crate_name, |
| got, |
| path.display() |
| )); |
| } |
| err.note(&msg); |
| err |
| } else if !self.rejected_via_kind.is_empty() { |
| let mut err = struct_span_err!( |
| self.sess, |
| self.span, |
| E0462, |
| "found staticlib `{}` instead of rlib or dylib{}", |
| self.crate_name, |
| add |
| ); |
| err.help("please recompile that crate using --crate-type lib"); |
| let mismatches = self.rejected_via_kind.iter(); |
| for &CrateMismatch { ref path, .. } in mismatches { |
| msg.push_str(&format!("\ncrate `{}`: {}", self.crate_name, path.display())); |
| } |
| err.note(&msg); |
| err |
| } else if !self.rejected_via_version.is_empty() { |
| let mut err = struct_span_err!( |
| self.sess, |
| self.span, |
| E0514, |
| "found crate `{}` compiled by an incompatible version \ |
| of rustc{}", |
| self.crate_name, |
| add |
| ); |
| err.help(&format!( |
| "please recompile that crate using this compiler ({})", |
| rustc_version() |
| )); |
| let mismatches = self.rejected_via_version.iter(); |
| for &CrateMismatch { ref path, ref got } in mismatches { |
| msg.push_str(&format!( |
| "\ncrate `{}` compiled by {}: {}", |
| self.crate_name, |
| got, |
| path.display() |
| )); |
| } |
| err.note(&msg); |
| err |
| } else { |
| let mut err = struct_span_err!( |
| self.sess, |
| self.span, |
| E0463, |
| "can't find crate for `{}`{}", |
| self.crate_name, |
| add |
| ); |
| |
| if (self.crate_name == sym::std || self.crate_name == sym::core) |
| && self.triple != TargetTriple::from_triple(config::host_triple()) |
| { |
| err.note(&format!("the `{}` target may not be installed", self.triple)); |
| } else if self.crate_name == sym::profiler_builtins { |
| err.note(&"the compiler may have been built without the profiler runtime"); |
| } |
| err.span_label(self.span, "can't find crate"); |
| err |
| }; |
| |
| if !self.rejected_via_filename.is_empty() { |
| let dylibname = self.dylibname(); |
| let mismatches = self.rejected_via_filename.iter(); |
| for &CrateMismatch { ref path, .. } in mismatches { |
| err.note(&format!( |
| "extern location for {} is of an unknown type: {}", |
| self.crate_name, |
| path.display() |
| )) |
| .help(&format!( |
| "file name should be lib*.rlib or {}*.{}", |
| dylibname.0, dylibname.1 |
| )); |
| } |
| } |
| |
| err.emit(); |
| self.sess.abort_if_errors(); |
| unreachable!(); |
| } |
| |
| fn find_library_crate( |
| &mut self, |
| extra_prefix: &str, |
| seen_paths: &mut FxHashSet<PathBuf>, |
| ) -> Option<Library> { |
| let dypair = self.dylibname(); |
| let staticpair = self.staticlibname(); |
| |
| // want: crate_name.dir_part() + prefix + crate_name.file_part + "-" |
| let dylib_prefix = format!("{}{}{}", dypair.0, self.crate_name, extra_prefix); |
| let rlib_prefix = format!("lib{}{}", self.crate_name, extra_prefix); |
| let staticlib_prefix = format!("{}{}{}", staticpair.0, self.crate_name, extra_prefix); |
| |
| let mut candidates: FxHashMap<_, (FxHashMap<_, _>, FxHashMap<_, _>, FxHashMap<_, _>)> = |
| Default::default(); |
| let mut staticlibs = vec![]; |
| |
| // First, find all possible candidate rlibs and dylibs purely based on |
| // the name of the files themselves. We're trying to match against an |
| // exact crate name and a possibly an exact hash. |
| // |
| // During this step, we can filter all found libraries based on the |
| // name and id found in the crate id (we ignore the path portion for |
| // filename matching), as well as the exact hash (if specified). If we |
| // end up having many candidates, we must look at the metadata to |
| // perform exact matches against hashes/crate ids. Note that opening up |
| // the metadata is where we do an exact match against the full contents |
| // of the crate id (path/name/id). |
| // |
| // The goal of this step is to look at as little metadata as possible. |
| self.filesearch.search(|spf, kind| { |
| let file = match &spf.file_name_str { |
| None => return FileDoesntMatch, |
| Some(file) => file, |
| }; |
| let (hash, found_kind) = if file.starts_with(&rlib_prefix) && file.ends_with(".rlib") { |
| (&file[(rlib_prefix.len())..(file.len() - ".rlib".len())], CrateFlavor::Rlib) |
| } else if file.starts_with(&rlib_prefix) && file.ends_with(".rmeta") { |
| (&file[(rlib_prefix.len())..(file.len() - ".rmeta".len())], CrateFlavor::Rmeta) |
| } else if file.starts_with(&dylib_prefix) && file.ends_with(&dypair.1) { |
| (&file[(dylib_prefix.len())..(file.len() - dypair.1.len())], CrateFlavor::Dylib) |
| } else { |
| if file.starts_with(&staticlib_prefix) && file.ends_with(&staticpair.1) { |
| staticlibs |
| .push(CrateMismatch { path: spf.path.clone(), got: "static".to_string() }); |
| } |
| return FileDoesntMatch; |
| }; |
| |
| info!("lib candidate: {}", spf.path.display()); |
| |
| let hash_str = hash.to_string(); |
| let slot = candidates.entry(hash_str).or_default(); |
| let (ref mut rlibs, ref mut rmetas, ref mut dylibs) = *slot; |
| fs::canonicalize(&spf.path) |
| .map(|p| { |
| if seen_paths.contains(&p) { |
| return FileDoesntMatch; |
| }; |
| seen_paths.insert(p.clone()); |
| match found_kind { |
| CrateFlavor::Rlib => { |
| rlibs.insert(p, kind); |
| } |
| CrateFlavor::Rmeta => { |
| rmetas.insert(p, kind); |
| } |
| CrateFlavor::Dylib => { |
| dylibs.insert(p, kind); |
| } |
| } |
| FileMatches |
| }) |
| .unwrap_or(FileDoesntMatch) |
| }); |
| self.rejected_via_kind.extend(staticlibs); |
| |
| // We have now collected all known libraries into a set of candidates |
| // keyed of the filename hash listed. For each filename, we also have a |
| // list of rlibs/dylibs that apply. Here, we map each of these lists |
| // (per hash), to a Library candidate for returning. |
| // |
| // A Library candidate is created if the metadata for the set of |
| // libraries corresponds to the crate id and hash criteria that this |
| // search is being performed for. |
| let mut libraries = FxHashMap::default(); |
| for (_hash, (rlibs, rmetas, dylibs)) in candidates { |
| if let Some((svh, lib)) = self.extract_lib(rlibs, rmetas, dylibs) { |
| libraries.insert(svh, lib); |
| } |
| } |
| |
| // Having now translated all relevant found hashes into libraries, see |
| // what we've got and figure out if we found multiple candidates for |
| // libraries or not. |
| match libraries.len() { |
| 0 => None, |
| 1 => Some(libraries.into_iter().next().unwrap().1), |
| _ => { |
| let mut err = struct_span_err!( |
| self.sess, |
| self.span, |
| E0464, |
| "multiple matching crates for `{}`", |
| self.crate_name |
| ); |
| let candidates = libraries |
| .iter() |
| .filter_map(|(_, lib)| { |
| let crate_name = &lib.metadata.get_root().name().as_str(); |
| match &(&lib.source.dylib, &lib.source.rlib) { |
| &(&Some((ref pd, _)), &Some((ref pr, _))) => Some(format!( |
| "\ncrate `{}`: {}\n{:>padding$}", |
| crate_name, |
| pd.display(), |
| pr.display(), |
| padding = 8 + crate_name.len() |
| )), |
| &(&Some((ref p, _)), &None) | &(&None, &Some((ref p, _))) => { |
| Some(format!("\ncrate `{}`: {}", crate_name, p.display())) |
| } |
| &(&None, &None) => None, |
| } |
| }) |
| .collect::<String>(); |
| err.note(&format!("candidates:{}", candidates)); |
| err.emit(); |
| None |
| } |
| } |
| } |
| |
| fn extract_lib( |
| &mut self, |
| rlibs: FxHashMap<PathBuf, PathKind>, |
| rmetas: FxHashMap<PathBuf, PathKind>, |
| dylibs: FxHashMap<PathBuf, PathKind>, |
| ) -> Option<(Svh, Library)> { |
| let mut slot = None; |
| // Order here matters, rmeta should come first. See comment in |
| // `extract_one` below. |
| let source = CrateSource { |
| rmeta: self.extract_one(rmetas, CrateFlavor::Rmeta, &mut slot), |
| rlib: self.extract_one(rlibs, CrateFlavor::Rlib, &mut slot), |
| dylib: self.extract_one(dylibs, CrateFlavor::Dylib, &mut slot), |
| }; |
| slot.map(|(svh, metadata)| (svh, Library { source, metadata })) |
| } |
| |
| fn needs_crate_flavor(&self, flavor: CrateFlavor) -> bool { |
| if flavor == CrateFlavor::Dylib && self.is_proc_macro == Some(true) { |
| return true; |
| } |
| |
| // The all loop is because `--crate-type=rlib --crate-type=rlib` is |
| // legal and produces both inside this type. |
| let is_rlib = self.sess.crate_types().iter().all(|c| *c == CrateType::Rlib); |
| let needs_object_code = self.sess.opts.output_types.should_codegen(); |
| // If we're producing an rlib, then we don't need object code. |
| // Or, if we're not producing object code, then we don't need it either |
| // (e.g., if we're a cdylib but emitting just metadata). |
| if is_rlib || !needs_object_code { |
| flavor == CrateFlavor::Rmeta |
| } else { |
| // we need all flavors (perhaps not true, but what we do for now) |
| true |
| } |
| } |
| |
| // Attempts to extract *one* library from the set `m`. If the set has no |
| // elements, `None` is returned. If the set has more than one element, then |
| // the errors and notes are emitted about the set of libraries. |
| // |
| // With only one library in the set, this function will extract it, and then |
| // read the metadata from it if `*slot` is `None`. If the metadata couldn't |
| // be read, it is assumed that the file isn't a valid rust library (no |
| // errors are emitted). |
| fn extract_one( |
| &mut self, |
| m: FxHashMap<PathBuf, PathKind>, |
| flavor: CrateFlavor, |
| slot: &mut Option<(Svh, MetadataBlob)>, |
| ) -> Option<(PathBuf, PathKind)> { |
| let mut ret: Option<(PathBuf, PathKind)> = None; |
| let mut error = 0; |
| |
| // If we are producing an rlib, and we've already loaded metadata, then |
| // we should not attempt to discover further crate sources (unless we're |
| // locating a proc macro; exact logic is in needs_crate_flavor). This means |
| // that under -Zbinary-dep-depinfo we will not emit a dependency edge on |
| // the *unused* rlib, and by returning `None` here immediately we |
| // guarantee that we do indeed not use it. |
| // |
| // See also #68149 which provides more detail on why emitting the |
| // dependency on the rlib is a bad thing. |
| // |
| // We currently do not verify that these other sources are even in sync, |
| // and this is arguably a bug (see #10786), but because reading metadata |
| // is quite slow (especially from dylibs) we currently do not read it |
| // from the other crate sources. |
| if slot.is_some() { |
| if m.is_empty() || !self.needs_crate_flavor(flavor) { |
| return None; |
| } else if m.len() == 1 { |
| return Some(m.into_iter().next().unwrap()); |
| } |
| } |
| |
| let mut err: Option<DiagnosticBuilder<'_>> = None; |
| for (lib, kind) in m { |
| info!("{} reading metadata from: {}", flavor, lib.display()); |
| let (hash, metadata) = |
| match get_metadata_section(self.target, flavor, &lib, self.metadata_loader) { |
| Ok(blob) => { |
| if let Some(h) = self.crate_matches(&blob, &lib) { |
| (h, blob) |
| } else { |
| info!("metadata mismatch"); |
| continue; |
| } |
| } |
| Err(err) => { |
| warn!("no metadata found: {}", err); |
| continue; |
| } |
| }; |
| // If we see multiple hashes, emit an error about duplicate candidates. |
| if slot.as_ref().map_or(false, |s| s.0 != hash) { |
| let mut e = struct_span_err!( |
| self.sess, |
| self.span, |
| E0465, |
| "multiple {} candidates for `{}` found", |
| flavor, |
| self.crate_name |
| ); |
| e.span_note( |
| self.span, |
| &format!(r"candidate #1: {}", ret.as_ref().unwrap().0.display()), |
| ); |
| if let Some(ref mut e) = err { |
| e.emit(); |
| } |
| err = Some(e); |
| error = 1; |
| *slot = None; |
| } |
| if error > 0 { |
| error += 1; |
| err.as_mut() |
| .unwrap() |
| .span_note(self.span, &format!(r"candidate #{}: {}", error, lib.display())); |
| continue; |
| } |
| |
| // Ok so at this point we've determined that `(lib, kind)` above is |
| // a candidate crate to load, and that `slot` is either none (this |
| // is the first crate of its kind) or if some the previous path has |
| // the exact same hash (e.g., it's the exact same crate). |
| // |
| // In principle these two candidate crates are exactly the same so |
| // we can choose either of them to link. As a stupidly gross hack, |
| // however, we favor crate in the sysroot. |
| // |
| // You can find more info in rust-lang/rust#39518 and various linked |
| // issues, but the general gist is that during testing libstd the |
| // compilers has two candidates to choose from: one in the sysroot |
| // and one in the deps folder. These two crates are the exact same |
| // crate but if the compiler chooses the one in the deps folder |
| // it'll cause spurious errors on Windows. |
| // |
| // As a result, we favor the sysroot crate here. Note that the |
| // candidates are all canonicalized, so we canonicalize the sysroot |
| // as well. |
| if let Some((ref prev, _)) = ret { |
| let sysroot = &self.sess.sysroot; |
| let sysroot = sysroot.canonicalize().unwrap_or_else(|_| sysroot.to_path_buf()); |
| if prev.starts_with(&sysroot) { |
| continue; |
| } |
| } |
| *slot = Some((hash, metadata)); |
| ret = Some((lib, kind)); |
| } |
| |
| if error > 0 { |
| err.unwrap().emit(); |
| None |
| } else { |
| ret |
| } |
| } |
| |
| fn crate_matches(&mut self, metadata: &MetadataBlob, libpath: &Path) -> Option<Svh> { |
| let rustc_version = rustc_version(); |
| let found_version = metadata.get_rustc_version(); |
| if found_version != rustc_version { |
| info!("Rejecting via version: expected {} got {}", rustc_version, found_version); |
| self.rejected_via_version |
| .push(CrateMismatch { path: libpath.to_path_buf(), got: found_version }); |
| return None; |
| } |
| |
| let root = metadata.get_root(); |
| if let Some(expected_is_proc_macro) = self.is_proc_macro { |
| let is_proc_macro = root.is_proc_macro_crate(); |
| if is_proc_macro != expected_is_proc_macro { |
| info!( |
| "Rejecting via proc macro: expected {} got {}", |
| expected_is_proc_macro, is_proc_macro |
| ); |
| return None; |
| } |
| } |
| |
| if self.exact_paths.is_empty() { |
| if self.crate_name != root.name() { |
| info!("Rejecting via crate name"); |
| return None; |
| } |
| } |
| |
| if root.triple() != &self.triple { |
| info!("Rejecting via crate triple: expected {} got {}", self.triple, root.triple()); |
| self.rejected_via_triple.push(CrateMismatch { |
| path: libpath.to_path_buf(), |
| got: root.triple().to_string(), |
| }); |
| return None; |
| } |
| |
| let hash = root.hash(); |
| if let Some(expected_hash) = self.hash { |
| if hash != expected_hash { |
| info!("Rejecting via hash: expected {} got {}", expected_hash, hash); |
| self.rejected_via_hash |
| .push(CrateMismatch { path: libpath.to_path_buf(), got: hash.to_string() }); |
| return None; |
| } |
| } |
| |
| Some(hash) |
| } |
| |
| // Returns the corresponding (prefix, suffix) that files need to have for |
| // dynamic libraries |
| fn dylibname(&self) -> (String, String) { |
| let t = &self.target; |
| (t.options.dll_prefix.clone(), t.options.dll_suffix.clone()) |
| } |
| |
| // Returns the corresponding (prefix, suffix) that files need to have for |
| // static libraries |
| fn staticlibname(&self) -> (String, String) { |
| let t = &self.target; |
| (t.options.staticlib_prefix.clone(), t.options.staticlib_suffix.clone()) |
| } |
| |
| fn find_commandline_library(&mut self) -> Option<Library> { |
| // First, filter out all libraries that look suspicious. We only accept |
| // files which actually exist that have the correct naming scheme for |
| // rlibs/dylibs. |
| let sess = self.sess; |
| let dylibname = self.dylibname(); |
| let mut rlibs = FxHashMap::default(); |
| let mut rmetas = FxHashMap::default(); |
| let mut dylibs = FxHashMap::default(); |
| { |
| let crate_name = self.crate_name; |
| let rejected_via_filename = &mut self.rejected_via_filename; |
| let locs = self.exact_paths.iter().filter(|loc| { |
| if !loc.exists() { |
| sess.err(&format!( |
| "extern location for {} does not exist: {}", |
| crate_name, |
| loc.display() |
| )); |
| return false; |
| } |
| let file = match loc.file_name().and_then(|s| s.to_str()) { |
| Some(file) => file, |
| None => { |
| sess.err(&format!( |
| "extern location for {} is not a file: {}", |
| crate_name, |
| loc.display() |
| )); |
| return false; |
| } |
| }; |
| if file.starts_with("lib") && (file.ends_with(".rlib") || file.ends_with(".rmeta")) |
| { |
| return true; |
| } else { |
| let (ref prefix, ref suffix) = dylibname; |
| if file.starts_with(&prefix[..]) && file.ends_with(&suffix[..]) { |
| return true; |
| } |
| } |
| |
| rejected_via_filename |
| .push(CrateMismatch { path: (*loc).clone(), got: String::new() }); |
| |
| false |
| }); |
| |
| // Now that we have an iterator of good candidates, make sure |
| // there's at most one rlib and at most one dylib. |
| for loc in locs { |
| if loc.file_name().unwrap().to_str().unwrap().ends_with(".rlib") { |
| rlibs.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag); |
| } else if loc.file_name().unwrap().to_str().unwrap().ends_with(".rmeta") { |
| rmetas.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag); |
| } else { |
| dylibs.insert(fs::canonicalize(&loc).unwrap(), PathKind::ExternFlag); |
| } |
| } |
| }; |
| |
| // Extract the dylib/rlib/rmeta triple. |
| self.extract_lib(rlibs, rmetas, dylibs).map(|(_, lib)| lib) |
| } |
| } |
| |
| // Just a small wrapper to time how long reading metadata takes. |
| fn get_metadata_section( |
| target: &Target, |
| flavor: CrateFlavor, |
| filename: &Path, |
| loader: &dyn MetadataLoader, |
| ) -> Result<MetadataBlob, String> { |
| let start = Instant::now(); |
| let ret = get_metadata_section_imp(target, flavor, filename, loader); |
| info!("reading {:?} => {:?}", filename.file_name().unwrap(), start.elapsed()); |
| ret |
| } |
| |
| /// A trivial wrapper for `Mmap` that implements `StableDeref`. |
| struct StableDerefMmap(memmap::Mmap); |
| |
| impl Deref for StableDerefMmap { |
| type Target = [u8]; |
| |
| fn deref(&self) -> &[u8] { |
| self.0.deref() |
| } |
| } |
| |
| unsafe impl stable_deref_trait::StableDeref for StableDerefMmap {} |
| |
| fn get_metadata_section_imp( |
| target: &Target, |
| flavor: CrateFlavor, |
| filename: &Path, |
| loader: &dyn MetadataLoader, |
| ) -> Result<MetadataBlob, String> { |
| if !filename.exists() { |
| return Err(format!("no such file: '{}'", filename.display())); |
| } |
| let raw_bytes: MetadataRef = match flavor { |
| CrateFlavor::Rlib => loader.get_rlib_metadata(target, filename)?, |
| CrateFlavor::Dylib => { |
| let buf = loader.get_dylib_metadata(target, filename)?; |
| // The header is uncompressed |
| let header_len = METADATA_HEADER.len(); |
| debug!("checking {} bytes of metadata-version stamp", header_len); |
| let header = &buf[..cmp::min(header_len, buf.len())]; |
| if header != METADATA_HEADER { |
| return Err(format!( |
| "incompatible metadata version found: '{}'", |
| filename.display() |
| )); |
| } |
| |
| // Header is okay -> inflate the actual metadata |
| let compressed_bytes = &buf[header_len..]; |
| debug!("inflating {} bytes of compressed metadata", compressed_bytes.len()); |
| let mut inflated = Vec::new(); |
| match DeflateDecoder::new(compressed_bytes).read_to_end(&mut inflated) { |
| Ok(_) => rustc_erase_owner!(OwningRef::new(inflated).map_owner_box()), |
| Err(_) => { |
| return Err(format!("failed to decompress metadata: {}", filename.display())); |
| } |
| } |
| } |
| CrateFlavor::Rmeta => { |
| // mmap the file, because only a small fraction of it is read. |
| let file = std::fs::File::open(filename) |
| .map_err(|_| format!("failed to open rmeta metadata: '{}'", filename.display()))?; |
| let mmap = unsafe { memmap::Mmap::map(&file) }; |
| let mmap = mmap |
| .map_err(|_| format!("failed to mmap rmeta metadata: '{}'", filename.display()))?; |
| |
| rustc_erase_owner!(OwningRef::new(StableDerefMmap(mmap)).map_owner_box()) |
| } |
| }; |
| let blob = MetadataBlob::new(raw_bytes); |
| if blob.is_compatible() { |
| Ok(blob) |
| } else { |
| Err(format!("incompatible metadata version found: '{}'", filename.display())) |
| } |
| } |
| |
| /// Look for a plugin registrar. Returns its library path and crate disambiguator. |
| pub fn find_plugin_registrar( |
| sess: &Session, |
| metadata_loader: &dyn MetadataLoader, |
| span: Span, |
| name: Symbol, |
| ) -> Option<(PathBuf, CrateDisambiguator)> { |
| info!("find plugin registrar `{}`", name); |
| let target_triple = sess.opts.target_triple.clone(); |
| let host_triple = TargetTriple::from_triple(config::host_triple()); |
| let is_cross = target_triple != host_triple; |
| let mut target_only = false; |
| let mut locator = CrateLocator::new( |
| sess, |
| metadata_loader, |
| name, |
| None, // hash |
| None, // host_hash |
| None, // extra_filename |
| true, // is_host |
| PathKind::Crate, |
| span, |
| None, // root |
| None, // is_proc_macro |
| ); |
| |
| let library = locator.maybe_load_library_crate().or_else(|| { |
| if !is_cross { |
| return None; |
| } |
| // Try loading from target crates. This will abort later if we |
| // try to load a plugin registrar function, |
| target_only = true; |
| |
| locator.target = &sess.target.target; |
| locator.triple = target_triple; |
| locator.filesearch = sess.target_filesearch(PathKind::Crate); |
| |
| locator.maybe_load_library_crate() |
| }); |
| let library = match library { |
| Some(l) => l, |
| None => locator.report_errs(), |
| }; |
| |
| if target_only { |
| let message = format!( |
| "plugin `{}` is not available for triple `{}` (only found {})", |
| name, |
| config::host_triple(), |
| sess.opts.target_triple |
| ); |
| struct_span_err!(sess, span, E0456, "{}", &message).emit(); |
| return None; |
| } |
| |
| match library.source.dylib { |
| Some(dylib) => Some((dylib.0, library.metadata.get_root().disambiguator())), |
| None => { |
| struct_span_err!( |
| sess, |
| span, |
| E0457, |
| "plugin `{}` only found in rlib format, but must be available \ |
| in dylib format", |
| name |
| ) |
| .emit(); |
| // No need to abort because the loading code will just ignore this |
| // empty dylib. |
| None |
| } |
| } |
| } |
| |
| /// A diagnostic function for dumping crate metadata to an output stream. |
| pub fn list_file_metadata( |
| target: &Target, |
| path: &Path, |
| metadata_loader: &dyn MetadataLoader, |
| out: &mut dyn io::Write, |
| ) -> io::Result<()> { |
| let filename = path.file_name().unwrap().to_str().unwrap(); |
| let flavor = if filename.ends_with(".rlib") { |
| CrateFlavor::Rlib |
| } else if filename.ends_with(".rmeta") { |
| CrateFlavor::Rmeta |
| } else { |
| CrateFlavor::Dylib |
| }; |
| match get_metadata_section(target, flavor, path, metadata_loader) { |
| Ok(metadata) => metadata.list_crate_metadata(out), |
| Err(msg) => write!(out, "{}\n", msg), |
| } |
| } |
