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//! 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 is 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 std::borrow::Cow;
use std::io::{Read, Result as IoResult, Write};
use std::ops::Deref;
use std::path::{Path, PathBuf};
use std::{cmp, fmt};
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::memmap::Mmap;
use rustc_data_structures::owned_slice::slice_owned;
use rustc_data_structures::svh::Svh;
use rustc_errors::{DiagArgValue, IntoDiagArg};
use rustc_fs_util::try_canonicalize;
use rustc_session::cstore::CrateSource;
use rustc_session::filesearch::FileSearch;
use rustc_session::search_paths::PathKind;
use rustc_session::utils::CanonicalizedPath;
use rustc_session::Session;
use rustc_span::symbol::Symbol;
use rustc_span::Span;
use rustc_target::spec::{Target, TargetTriple};
use snap::read::FrameDecoder;
use tracing::{debug, info};
use crate::creader::{Library, MetadataLoader};
use crate::errors;
use crate::rmeta::{rustc_version, MetadataBlob, METADATA_HEADER};
#[derive(Clone)]
pub(crate) struct CrateLocator<'a> {
// Immutable per-session configuration.
only_needs_metadata: bool,
sysroot: &'a Path,
metadata_loader: &'a dyn MetadataLoader,
cfg_version: &'static str,
// Immutable per-search configuration.
crate_name: Symbol,
exact_paths: Vec<CanonicalizedPath>,
pub hash: Option<Svh>,
extra_filename: Option<&'a str>,
pub target: &'a Target,
pub triple: TargetTriple,
pub filesearch: FileSearch<'a>,
pub is_proc_macro: bool,
// Mutable in-progress state or output.
crate_rejections: CrateRejections,
}
#[derive(Clone)]
pub(crate) struct CratePaths {
name: Symbol,
source: CrateSource,
}
impl CratePaths {
pub(crate) fn new(name: Symbol, source: CrateSource) -> CratePaths {
CratePaths { name, source }
}
}
#[derive(Copy, Clone, PartialEq)]
pub(crate) 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 IntoDiagArg for CrateFlavor {
fn into_diag_arg(self) -> rustc_errors::DiagArgValue {
match self {
CrateFlavor::Rlib => DiagArgValue::Str(Cow::Borrowed("rlib")),
CrateFlavor::Rmeta => DiagArgValue::Str(Cow::Borrowed("rmeta")),
CrateFlavor::Dylib => DiagArgValue::Str(Cow::Borrowed("dylib")),
}
}
}
impl<'a> CrateLocator<'a> {
pub(crate) fn new(
sess: &'a Session,
metadata_loader: &'a dyn MetadataLoader,
crate_name: Symbol,
is_rlib: bool,
hash: Option<Svh>,
extra_filename: Option<&'a str>,
path_kind: PathKind,
) -> CrateLocator<'a> {
let needs_object_code = 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).
let only_needs_metadata = is_rlib || !needs_object_code;
CrateLocator {
only_needs_metadata,
sysroot: &sess.sysroot,
metadata_loader,
cfg_version: sess.cfg_version,
crate_name,
exact_paths: if hash.is_none() {
sess.opts
.externs
.get(crate_name.as_str())
.into_iter()
.filter_map(|entry| entry.files())
.flatten()
.cloned()
.collect()
} else {
// SVH being specified means this is a transitive dependency,
// so `--extern` options do not apply.
Vec::new()
},
hash,
extra_filename,
target: &sess.target,
triple: sess.opts.target_triple.clone(),
filesearch: sess.target_filesearch(path_kind),
is_proc_macro: false,
crate_rejections: CrateRejections::default(),
}
}
pub(crate) fn reset(&mut self) {
self.crate_rejections.via_hash.clear();
self.crate_rejections.via_triple.clear();
self.crate_rejections.via_kind.clear();
self.crate_rejections.via_version.clear();
self.crate_rejections.via_filename.clear();
self.crate_rejections.via_invalid.clear();
}
pub(crate) fn maybe_load_library_crate(&mut self) -> Result<Option<Library>, CrateError> {
if !self.exact_paths.is_empty() {
return self.find_commandline_library();
}
let mut seen_paths = FxHashSet::default();
if let Some(extra_filename) = self.extra_filename {
if let library @ Some(_) = self.find_library_crate(extra_filename, &mut seen_paths)? {
return Ok(library);
}
}
self.find_library_crate("", &mut seen_paths)
}
fn find_library_crate(
&mut self,
extra_prefix: &str,
seen_paths: &mut FxHashSet<PathBuf>,
) -> Result<Option<Library>, CrateError> {
let rmeta_prefix = &format!("lib{}{}", self.crate_name, extra_prefix);
let rlib_prefix = rmeta_prefix;
let dylib_prefix =
&format!("{}{}{}", self.target.dll_prefix, self.crate_name, extra_prefix);
let staticlib_prefix =
&format!("{}{}{}", self.target.staticlib_prefix, self.crate_name, extra_prefix);
let rmeta_suffix = ".rmeta";
let rlib_suffix = ".rlib";
let dylib_suffix = &self.target.dll_suffix;
let staticlib_suffix = &self.target.staticlib_suffix;
let mut candidates: FxHashMap<_, (FxHashMap<_, _>, FxHashMap<_, _>, FxHashMap<_, _>)> =
Default::default();
// 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.
// Unfortunately, the prefix-based matching sometimes is over-eager.
// E.g. if `rlib_suffix` is `libstd` it'll match the file
// `libstd_detect-8d6701fb958915ad.rlib` (incorrect) as well as
// `libstd-f3ab5b1dea981f17.rlib` (correct). But this is hard to avoid
// given that `extra_filename` comes from the `-C extra-filename`
// option and thus can be anything, and the incorrect match will be
// handled safely in `extract_one`.
for search_path in self.filesearch.search_paths() {
debug!("searching {}", search_path.dir.display());
for spf in search_path.files.iter() {
debug!("testing {}", spf.path.display());
let f = &spf.file_name_str;
let (hash, kind) = if let Some(f) = f.strip_prefix(rlib_prefix)
&& let Some(f) = f.strip_suffix(rlib_suffix)
{
(f, CrateFlavor::Rlib)
} else if let Some(f) = f.strip_prefix(rmeta_prefix)
&& let Some(f) = f.strip_suffix(rmeta_suffix)
{
(f, CrateFlavor::Rmeta)
} else if let Some(f) = f.strip_prefix(dylib_prefix)
&& let Some(f) = f.strip_suffix(dylib_suffix.as_ref())
{
(f, CrateFlavor::Dylib)
} else {
if f.starts_with(staticlib_prefix) && f.ends_with(staticlib_suffix.as_ref()) {
self.crate_rejections.via_kind.push(CrateMismatch {
path: spf.path.clone(),
got: "static".to_string(),
});
}
continue;
};
info!("lib candidate: {}", spf.path.display());
let (rlibs, rmetas, dylibs) = candidates.entry(hash.to_string()).or_default();
let path = try_canonicalize(&spf.path).unwrap_or_else(|_| spf.path.clone());
if seen_paths.contains(&path) {
continue;
};
seen_paths.insert(path.clone());
match kind {
CrateFlavor::Rlib => rlibs.insert(path, search_path.kind),
CrateFlavor::Rmeta => rmetas.insert(path, search_path.kind),
CrateFlavor::Dylib => dylibs.insert(path, search_path.kind),
};
}
}
// 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 => Ok(None),
1 => Ok(Some(libraries.into_iter().next().unwrap().1)),
_ => {
let mut libraries: Vec<_> = libraries.into_values().collect();
libraries.sort_by_cached_key(|lib| lib.source.paths().next().unwrap().clone());
let candidates = libraries
.iter()
.map(|lib| lib.source.paths().next().unwrap().clone())
.collect::<Vec<_>>();
Err(CrateError::MultipleCandidates(
self.crate_name,
// these are the same for all candidates
get_flavor_from_path(candidates.first().unwrap()),
candidates,
))
}
}
}
fn extract_lib(
&mut self,
rlibs: FxHashMap<PathBuf, PathKind>,
rmetas: FxHashMap<PathBuf, PathKind>,
dylibs: FxHashMap<PathBuf, PathKind>,
) -> Result<Option<(Svh, Library)>, CrateError> {
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)?,
};
Ok(slot.map(|(svh, metadata, _)| (svh, Library { source, metadata })))
}
fn needs_crate_flavor(&self, flavor: CrateFlavor) -> bool {
if flavor == CrateFlavor::Dylib && self.is_proc_macro {
return true;
}
if self.only_needs_metadata {
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).
//
// The `PathBuf` in `slot` will only be used for diagnostic purposes.
fn extract_one(
&mut self,
m: FxHashMap<PathBuf, PathKind>,
flavor: CrateFlavor,
slot: &mut Option<(Svh, MetadataBlob, PathBuf)>,
) -> Result<Option<(PathBuf, PathKind)>, CrateError> {
// 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.
if slot.is_some() {
if m.is_empty() || !self.needs_crate_flavor(flavor) {
return Ok(None);
}
}
let mut ret: Option<(PathBuf, PathKind)> = None;
let mut err_data: Option<Vec<PathBuf>> = None;
for (lib, kind) in m {
info!("{} reading metadata from: {}", flavor, lib.display());
if flavor == CrateFlavor::Rmeta && lib.metadata().is_ok_and(|m| m.len() == 0) {
// Empty files will cause get_metadata_section to fail. Rmeta
// files can be empty, for example with binaries (which can
// often appear with `cargo check` when checking a library as
// a unittest). We don't want to emit a user-visible warning
// in this case as it is not a real problem.
debug!("skipping empty file");
continue;
}
let (hash, metadata) = match get_metadata_section(
self.target,
flavor,
&lib,
self.metadata_loader,
self.cfg_version,
) {
Ok(blob) => {
if let Some(h) = self.crate_matches(&blob, &lib) {
(h, blob)
} else {
info!("metadata mismatch");
continue;
}
}
Err(MetadataError::VersionMismatch { expected_version, found_version }) => {
// The file was present and created by the same compiler version, but we
// couldn't load it for some reason. Give a hard error instead of silently
// ignoring it, but only if we would have given an error anyway.
info!(
"Rejecting via version: expected {} got {}",
expected_version, found_version
);
self.crate_rejections
.via_version
.push(CrateMismatch { path: lib, got: found_version });
continue;
}
Err(MetadataError::LoadFailure(err)) => {
info!("no metadata found: {}", err);
// The file was present and created by the same compiler version, but we
// couldn't load it for some reason. Give a hard error instead of silently
// ignoring it, but only if we would have given an error anyway.
self.crate_rejections.via_invalid.push(CrateMismatch { path: lib, got: err });
continue;
}
Err(err @ MetadataError::NotPresent(_)) => {
info!("no metadata found: {}", err);
continue;
}
};
// If we see multiple hashes, emit an error about duplicate candidates.
if slot.as_ref().is_some_and(|s| s.0 != hash) {
if let Some(candidates) = err_data {
return Err(CrateError::MultipleCandidates(
self.crate_name,
flavor,
candidates,
));
}
err_data = Some(vec![slot.take().unwrap().2]);
}
if let Some(candidates) = &mut err_data {
candidates.push(lib);
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((prev, _)) = &ret {
let sysroot = self.sysroot;
let sysroot = try_canonicalize(sysroot).unwrap_or_else(|_| sysroot.to_path_buf());
if prev.starts_with(&sysroot) {
continue;
}
}
*slot = Some((hash, metadata, lib.clone()));
ret = Some((lib, kind));
}
if let Some(candidates) = err_data {
Err(CrateError::MultipleCandidates(self.crate_name, flavor, candidates))
} else {
Ok(ret)
}
}
fn crate_matches(&mut self, metadata: &MetadataBlob, libpath: &Path) -> Option<Svh> {
let header = metadata.get_header();
if header.is_proc_macro_crate != self.is_proc_macro {
info!(
"Rejecting via proc macro: expected {} got {}",
self.is_proc_macro, header.is_proc_macro_crate,
);
return None;
}
if self.exact_paths.is_empty() && self.crate_name != header.name {
info!("Rejecting via crate name");
return None;
}
if header.triple != self.triple {
info!("Rejecting via crate triple: expected {} got {}", self.triple, header.triple);
self.crate_rejections.via_triple.push(CrateMismatch {
path: libpath.to_path_buf(),
got: header.triple.to_string(),
});
return None;
}
let hash = header.hash;
if let Some(expected_hash) = self.hash {
if hash != expected_hash {
info!("Rejecting via hash: expected {} got {}", expected_hash, hash);
self.crate_rejections
.via_hash
.push(CrateMismatch { path: libpath.to_path_buf(), got: hash.to_string() });
return None;
}
}
Some(hash)
}
fn find_commandline_library(&mut self) -> Result<Option<Library>, CrateError> {
// 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 mut rlibs = FxHashMap::default();
let mut rmetas = FxHashMap::default();
let mut dylibs = FxHashMap::default();
for loc in &self.exact_paths {
if !loc.canonicalized().exists() {
return Err(CrateError::ExternLocationNotExist(
self.crate_name,
loc.original().clone(),
));
}
if !loc.original().is_file() {
return Err(CrateError::ExternLocationNotFile(
self.crate_name,
loc.original().clone(),
));
}
let Some(file) = loc.original().file_name().and_then(|s| s.to_str()) else {
return Err(CrateError::ExternLocationNotFile(
self.crate_name,
loc.original().clone(),
));
};
if file.starts_with("lib") && (file.ends_with(".rlib") || file.ends_with(".rmeta"))
|| file.starts_with(self.target.dll_prefix.as_ref())
&& file.ends_with(self.target.dll_suffix.as_ref())
{
// Make sure there's at most one rlib and at most one dylib.
// Note to take care and match against the non-canonicalized name:
// some systems save build artifacts into content-addressed stores
// that do not preserve extensions, and then link to them using
// e.g. symbolic links. If we canonicalize too early, we resolve
// the symlink, the file type is lost and we might treat rlibs and
// rmetas as dylibs.
let loc_canon = loc.canonicalized().clone();
let loc = loc.original();
if loc.file_name().unwrap().to_str().unwrap().ends_with(".rlib") {
rlibs.insert(loc_canon, PathKind::ExternFlag);
} else if loc.file_name().unwrap().to_str().unwrap().ends_with(".rmeta") {
rmetas.insert(loc_canon, PathKind::ExternFlag);
} else {
dylibs.insert(loc_canon, PathKind::ExternFlag);
}
} else {
self.crate_rejections
.via_filename
.push(CrateMismatch { path: loc.original().clone(), got: String::new() });
}
}
// Extract the dylib/rlib/rmeta triple.
Ok(self.extract_lib(rlibs, rmetas, dylibs)?.map(|(_, lib)| lib))
}
pub(crate) fn into_error(self, root: Option<CratePaths>) -> CrateError {
CrateError::LocatorCombined(Box::new(CombinedLocatorError {
crate_name: self.crate_name,
root,
triple: self.triple,
dll_prefix: self.target.dll_prefix.to_string(),
dll_suffix: self.target.dll_suffix.to_string(),
crate_rejections: self.crate_rejections,
}))
}
}
fn get_metadata_section<'p>(
target: &Target,
flavor: CrateFlavor,
filename: &'p Path,
loader: &dyn MetadataLoader,
cfg_version: &'static str,
) -> Result<MetadataBlob, MetadataError<'p>> {
if !filename.exists() {
return Err(MetadataError::NotPresent(filename));
}
let raw_bytes = match flavor {
CrateFlavor::Rlib => {
loader.get_rlib_metadata(target, filename).map_err(MetadataError::LoadFailure)?
}
CrateFlavor::Dylib => {
let buf =
loader.get_dylib_metadata(target, filename).map_err(MetadataError::LoadFailure)?;
// The header is uncompressed
let header_len = METADATA_HEADER.len();
// header + u64 length of data
let data_start = header_len + 8;
debug!("checking {} bytes of metadata-version stamp", header_len);
let header = &buf[..cmp::min(header_len, buf.len())];
if header != METADATA_HEADER {
return Err(MetadataError::LoadFailure(format!(
"invalid metadata version found: {}",
filename.display()
)));
}
// Length of the compressed stream - this allows linkers to pad the section if they want
let Ok(len_bytes) =
<[u8; 8]>::try_from(&buf[header_len..cmp::min(data_start, buf.len())])
else {
return Err(MetadataError::LoadFailure(
"invalid metadata length found".to_string(),
));
};
let compressed_len = u64::from_le_bytes(len_bytes) as usize;
// Header is okay -> inflate the actual metadata
let compressed_bytes = buf.slice(|buf| &buf[data_start..(data_start + compressed_len)]);
if &compressed_bytes[..cmp::min(METADATA_HEADER.len(), compressed_bytes.len())]
== METADATA_HEADER
{
// The metadata was not actually compressed.
compressed_bytes
} else {
debug!("inflating {} bytes of compressed metadata", compressed_bytes.len());
// Assume the decompressed data will be at least the size of the compressed data, so we
// don't have to grow the buffer as much.
let mut inflated = Vec::with_capacity(compressed_bytes.len());
FrameDecoder::new(&*compressed_bytes).read_to_end(&mut inflated).map_err(|_| {
MetadataError::LoadFailure(format!(
"failed to decompress metadata: {}",
filename.display()
))
})?;
slice_owned(inflated, Deref::deref)
}
}
CrateFlavor::Rmeta => {
// mmap the file, because only a small fraction of it is read.
let file = std::fs::File::open(filename).map_err(|_| {
MetadataError::LoadFailure(format!(
"failed to open rmeta metadata: '{}'",
filename.display()
))
})?;
let mmap = unsafe { Mmap::map(file) };
let mmap = mmap.map_err(|_| {
MetadataError::LoadFailure(format!(
"failed to mmap rmeta metadata: '{}'",
filename.display()
))
})?;
slice_owned(mmap, Deref::deref)
}
};
let Ok(blob) = MetadataBlob::new(raw_bytes) else {
return Err(MetadataError::LoadFailure(format!(
"corrupt metadata encountered in {}",
filename.display()
)));
};
match blob.check_compatibility(cfg_version) {
Ok(()) => Ok(blob),
Err(None) => Err(MetadataError::LoadFailure(format!(
"invalid metadata version found: {}",
filename.display()
))),
Err(Some(found_version)) => {
return Err(MetadataError::VersionMismatch {
expected_version: rustc_version(cfg_version),
found_version,
});
}
}
}
/// 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 Write,
ls_kinds: &[String],
cfg_version: &'static str,
) -> IoResult<()> {
let flavor = get_flavor_from_path(path);
match get_metadata_section(target, flavor, path, metadata_loader, cfg_version) {
Ok(metadata) => metadata.list_crate_metadata(out, ls_kinds),
Err(msg) => write!(out, "{msg}\n"),
}
}
fn get_flavor_from_path(path: &Path) -> CrateFlavor {
let filename = path.file_name().unwrap().to_str().unwrap();
if filename.ends_with(".rlib") {
CrateFlavor::Rlib
} else if filename.ends_with(".rmeta") {
CrateFlavor::Rmeta
} else {
CrateFlavor::Dylib
}
}
// ------------------------------------------ Error reporting -------------------------------------
#[derive(Clone)]
struct CrateMismatch {
path: PathBuf,
got: String,
}
#[derive(Clone, Default)]
struct CrateRejections {
via_hash: Vec<CrateMismatch>,
via_triple: Vec<CrateMismatch>,
via_kind: Vec<CrateMismatch>,
via_version: Vec<CrateMismatch>,
via_filename: Vec<CrateMismatch>,
via_invalid: Vec<CrateMismatch>,
}
/// Candidate rejection reasons collected during crate search.
/// If no candidate is accepted, then these reasons are presented to the user,
/// otherwise they are ignored.
pub(crate) struct CombinedLocatorError {
crate_name: Symbol,
root: Option<CratePaths>,
triple: TargetTriple,
dll_prefix: String,
dll_suffix: String,
crate_rejections: CrateRejections,
}
pub(crate) enum CrateError {
NonAsciiName(Symbol),
ExternLocationNotExist(Symbol, PathBuf),
ExternLocationNotFile(Symbol, PathBuf),
MultipleCandidates(Symbol, CrateFlavor, Vec<PathBuf>),
SymbolConflictsCurrent(Symbol),
StableCrateIdCollision(Symbol, Symbol),
DlOpen(String, String),
DlSym(String, String),
LocatorCombined(Box<CombinedLocatorError>),
NotFound(Symbol),
}
enum MetadataError<'a> {
/// The file was missing.
NotPresent(&'a Path),
/// The file was present and invalid.
LoadFailure(String),
/// The file was present, but compiled with a different rustc version.
VersionMismatch { expected_version: String, found_version: String },
}
impl fmt::Display for MetadataError<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
MetadataError::NotPresent(filename) => {
f.write_str(&format!("no such file: '{}'", filename.display()))
}
MetadataError::LoadFailure(msg) => f.write_str(msg),
MetadataError::VersionMismatch { expected_version, found_version } => {
f.write_str(&format!(
"rustc version mismatch. expected {}, found {}",
expected_version, found_version,
))
}
}
}
}
impl CrateError {
pub(crate) fn report(self, sess: &Session, span: Span, missing_core: bool) {
let dcx = sess.dcx();
match self {
CrateError::NonAsciiName(crate_name) => {
dcx.emit_err(errors::NonAsciiName { span, crate_name });
}
CrateError::ExternLocationNotExist(crate_name, loc) => {
dcx.emit_err(errors::ExternLocationNotExist { span, crate_name, location: &loc });
}
CrateError::ExternLocationNotFile(crate_name, loc) => {
dcx.emit_err(errors::ExternLocationNotFile { span, crate_name, location: &loc });
}
CrateError::MultipleCandidates(crate_name, flavor, candidates) => {
dcx.emit_err(errors::MultipleCandidates { span, crate_name, flavor, candidates });
}
CrateError::SymbolConflictsCurrent(root_name) => {
dcx.emit_err(errors::SymbolConflictsCurrent { span, crate_name: root_name });
}
CrateError::StableCrateIdCollision(crate_name0, crate_name1) => {
dcx.emit_err(errors::StableCrateIdCollision { span, crate_name0, crate_name1 });
}
CrateError::DlOpen(path, err) | CrateError::DlSym(path, err) => {
dcx.emit_err(errors::DlError { span, path, err });
}
CrateError::LocatorCombined(locator) => {
let crate_name = locator.crate_name;
let add_info = match &locator.root {
None => String::new(),
Some(r) => format!(" which `{}` depends on", r.name),
};
if !locator.crate_rejections.via_filename.is_empty() {
let mismatches = locator.crate_rejections.via_filename.iter();
for CrateMismatch { path, .. } in mismatches {
dcx.emit_err(errors::CrateLocationUnknownType { span, path, crate_name });
dcx.emit_err(errors::LibFilenameForm {
span,
dll_prefix: &locator.dll_prefix,
dll_suffix: &locator.dll_suffix,
});
}
}
let mut found_crates = String::new();
if !locator.crate_rejections.via_hash.is_empty() {
let mismatches = locator.crate_rejections.via_hash.iter();
for CrateMismatch { path, .. } in mismatches {
found_crates.push_str(&format!(
"\ncrate `{}`: {}",
crate_name,
path.display()
));
}
if let Some(r) = locator.root {
for path in r.source.paths() {
found_crates.push_str(&format!(
"\ncrate `{}`: {}",
r.name,
path.display()
));
}
}
dcx.emit_err(errors::NewerCrateVersion {
span,
crate_name,
add_info,
found_crates,
});
} else if !locator.crate_rejections.via_triple.is_empty() {
let mismatches = locator.crate_rejections.via_triple.iter();
for CrateMismatch { path, got } in mismatches {
found_crates.push_str(&format!(
"\ncrate `{}`, target triple {}: {}",
crate_name,
got,
path.display(),
));
}
dcx.emit_err(errors::NoCrateWithTriple {
span,
crate_name,
locator_triple: locator.triple.triple(),
add_info,
found_crates,
});
} else if !locator.crate_rejections.via_kind.is_empty() {
let mismatches = locator.crate_rejections.via_kind.iter();
for CrateMismatch { path, .. } in mismatches {
found_crates.push_str(&format!(
"\ncrate `{}`: {}",
crate_name,
path.display()
));
}
dcx.emit_err(errors::FoundStaticlib {
span,
crate_name,
add_info,
found_crates,
});
} else if !locator.crate_rejections.via_version.is_empty() {
let mismatches = locator.crate_rejections.via_version.iter();
for CrateMismatch { path, got } in mismatches {
found_crates.push_str(&format!(
"\ncrate `{}` compiled by {}: {}",
crate_name,
got,
path.display(),
));
}
dcx.emit_err(errors::IncompatibleRustc {
span,
crate_name,
add_info,
found_crates,
rustc_version: rustc_version(sess.cfg_version),
});
} else if !locator.crate_rejections.via_invalid.is_empty() {
let mut crate_rejections = Vec::new();
for CrateMismatch { path: _, got } in locator.crate_rejections.via_invalid {
crate_rejections.push(got);
}
dcx.emit_err(errors::InvalidMetadataFiles {
span,
crate_name,
add_info,
crate_rejections,
});
} else {
let error = errors::CannotFindCrate {
span,
crate_name,
add_info,
missing_core,
current_crate: sess
.opts
.crate_name
.clone()
.unwrap_or("<unknown>".to_string()),
is_nightly_build: sess.is_nightly_build(),
profiler_runtime: Symbol::intern(&sess.opts.unstable_opts.profiler_runtime),
locator_triple: locator.triple,
is_ui_testing: sess.opts.unstable_opts.ui_testing,
};
// The diagnostic for missing core is very good, but it is followed by a lot of
// other diagnostics that do not add information.
if missing_core {
dcx.emit_fatal(error);
} else {
dcx.emit_err(error);
}
}
}
CrateError::NotFound(crate_name) => {
let error = errors::CannotFindCrate {
span,
crate_name,
add_info: String::new(),
missing_core,
current_crate: sess.opts.crate_name.clone().unwrap_or("<unknown>".to_string()),
is_nightly_build: sess.is_nightly_build(),
profiler_runtime: Symbol::intern(&sess.opts.unstable_opts.profiler_runtime),
locator_triple: sess.opts.target_triple.clone(),
is_ui_testing: sess.opts.unstable_opts.ui_testing,
};
// The diagnostic for missing core is very good, but it is followed by a lot of
// other diagnostics that do not add information.
if missing_core {
dcx.emit_fatal(error);
} else {
dcx.emit_err(error);
}
}
}
}
}