diff options
Diffstat (limited to 'third_party/rust/rustc-demangle/src/lib.rs')
| -rw-r--r-- | third_party/rust/rustc-demangle/src/lib.rs | 413 |
1 files changed, 413 insertions, 0 deletions
diff --git a/third_party/rust/rustc-demangle/src/lib.rs b/third_party/rust/rustc-demangle/src/lib.rs new file mode 100644 index 0000000000..d14f4f60ea --- /dev/null +++ b/third_party/rust/rustc-demangle/src/lib.rs @@ -0,0 +1,413 @@ +//! Demangle Rust compiler symbol names. +//! +//! This crate provides a `demangle` function which will return a `Demangle` +//! sentinel value that can be used to learn about the demangled version of a +//! symbol name. The demangled representation will be the same as the original +//! if it doesn't look like a mangled symbol name. +//! +//! `Demangle` can be formatted with the `Display` trait. The alternate +//! modifier (`#`) can be used to format the symbol name without the +//! trailing hash value. +//! +//! # Examples +//! +//! ``` +//! use rustc_demangle::demangle; +//! +//! assert_eq!(demangle("_ZN4testE").to_string(), "test"); +//! assert_eq!(demangle("_ZN3foo3barE").to_string(), "foo::bar"); +//! assert_eq!(demangle("foo").to_string(), "foo"); +//! // With hash +//! assert_eq!(format!("{}", demangle("_ZN3foo17h05af221e174051e9E")), "foo::h05af221e174051e9"); +//! // Without hash +//! assert_eq!(format!("{:#}", demangle("_ZN3foo17h05af221e174051e9E")), "foo"); +//! ``` + +#![no_std] +#![deny(missing_docs)] + +#[cfg(test)] +#[macro_use] +extern crate std; + +use core::fmt; + +/// Representation of a demangled symbol name. +pub struct Demangle<'a> { + original: &'a str, + inner: &'a str, + valid: bool, + /// The number of ::-separated elements in the original name. + elements: usize, +} + +/// De-mangles a Rust symbol into a more readable version +/// +/// All rust symbols by default are mangled as they contain characters that +/// cannot be represented in all object files. The mangling mechanism is similar +/// to C++'s, but Rust has a few specifics to handle items like lifetimes in +/// symbols. +/// +/// This function will take a **mangled** symbol (typically acquired from a +/// `Symbol` which is in turn resolved from a `Frame`) and then writes the +/// de-mangled version into the given `writer`. If the symbol does not look like +/// a mangled symbol, it is still written to `writer`. +/// +/// # Examples +/// +/// ``` +/// use rustc_demangle::demangle; +/// +/// assert_eq!(demangle("_ZN4testE").to_string(), "test"); +/// assert_eq!(demangle("_ZN3foo3barE").to_string(), "foo::bar"); +/// assert_eq!(demangle("foo").to_string(), "foo"); +/// ``` + +// All rust symbols are in theory lists of "::"-separated identifiers. Some +// assemblers, however, can't handle these characters in symbol names. To get +// around this, we use C++-style mangling. The mangling method is: +// +// 1. Prefix the symbol with "_ZN" +// 2. For each element of the path, emit the length plus the element +// 3. End the path with "E" +// +// For example, "_ZN4testE" => "test" and "_ZN3foo3barE" => "foo::bar". +// +// We're the ones printing our backtraces, so we can't rely on anything else to +// demangle our symbols. It's *much* nicer to look at demangled symbols, so +// this function is implemented to give us nice pretty output. +// +// Note that this demangler isn't quite as fancy as it could be. We have lots +// of other information in our symbols like hashes, version, type information, +// etc. Additionally, this doesn't handle glue symbols at all. +pub fn demangle(mut s: &str) -> Demangle { + // During ThinLTO LLVM may import and rename internal symbols, so strip out + // those endings first as they're on of the last manglings applied to symbol + // names. + let llvm = ".llvm."; + if let Some(i) = s.find(llvm) { + let candidate = &s[i + llvm.len()..]; + let all_hex = candidate.chars().all(|c| { + match c { + 'A' ... 'F' | '0' ... '9' | '@' => true, + _ => false, + } + }); + + if all_hex { + s = &s[..i]; + } + } + + // First validate the symbol. If it doesn't look like anything we're + // expecting, we just print it literally. Note that we must handle non-rust + // symbols because we could have any function in the backtrace. + let mut valid = true; + let mut inner = s; + if s.len() > 4 && s.starts_with("_ZN") && s.ends_with('E') { + inner = &s[3..s.len() - 1]; + } else if s.len() > 3 && s.starts_with("ZN") && s.ends_with('E') { + // On Windows, dbghelp strips leading underscores, so we accept "ZN...E" + // form too. + inner = &s[2..s.len() - 1]; + } else if s.len() > 5 && s.starts_with("__ZN") && s.ends_with('E') { + // On OSX, symbols are prefixed with an extra _ + inner = &s[4..s.len() - 1]; + } else { + valid = false; + } + + // only work with ascii text + if inner.bytes().any(|c| c & 0x80 != 0) { + valid = false; + } + + let mut elements = 0; + if valid { + let mut chars = inner.chars().peekable(); + while valid { + let mut i = 0usize; + while let Some(&c) = chars.peek() { + if !c.is_digit(10) { + break + } + chars.next(); + let next = i.checked_mul(10) + .and_then(|i| i.checked_add(c as usize - '0' as usize)); + i = match next { + Some(i) => i, + None => { + valid = false; + break + } + }; + } + + if i == 0 { + valid = chars.next().is_none(); + break; + } else if chars.by_ref().take(i).count() != i { + valid = false; + } else { + elements += 1; + } + } + } + + Demangle { + inner: inner, + valid: valid, + elements: elements, + original: s, + } +} + +/// Error returned from the `try_demangle` function below when demangling fails. +#[derive(Debug, Clone)] +pub struct TryDemangleError { + _priv: (), +} + +/// The same as `demangle`, except return an `Err` if the string does not appear +/// to be a Rust symbol, rather than "demangling" the given string as a no-op. +/// +/// ``` +/// extern crate rustc_demangle; +/// +/// let not_a_rust_symbol = "la la la"; +/// +/// // The `try_demangle` function will reject strings which are not Rust symbols. +/// assert!(rustc_demangle::try_demangle(not_a_rust_symbol).is_err()); +/// +/// // While `demangle` will just pass the non-symbol through as a no-op. +/// assert_eq!(rustc_demangle::demangle(not_a_rust_symbol).as_str(), not_a_rust_symbol); +/// ``` +pub fn try_demangle(s: &str) -> Result<Demangle, TryDemangleError> { + let sym = demangle(s); + if sym.valid { + Ok(sym) + } else { + Err(TryDemangleError { _priv: () }) + } +} + +impl<'a> Demangle<'a> { + /// Returns the underlying string that's being demangled. + pub fn as_str(&self) -> &'a str { + self.original + } +} + +// Rust hashes are hex digits with an `h` prepended. +fn is_rust_hash(s: &str) -> bool { + s.starts_with('h') && s[1..].chars().all(|c| c.is_digit(16)) +} + +impl<'a> fmt::Display for Demangle<'a> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + // Alright, let's do this. + if !self.valid { + return f.write_str(self.inner); + } + + let mut inner = self.inner; + for element in 0..self.elements { + let mut rest = inner; + while rest.chars().next().unwrap().is_digit(10) { + rest = &rest[1..]; + } + let i: usize = inner[..(inner.len() - rest.len())].parse().unwrap(); + inner = &rest[i..]; + rest = &rest[..i]; + // Skip printing the hash if alternate formatting + // was requested. + if f.alternate() && element+1 == self.elements && is_rust_hash(&rest) { + break; + } + if element != 0 { + try!(f.write_str("::")); + } + if rest.starts_with("_$") { + rest = &rest[1..]; + } + while !rest.is_empty() { + if rest.starts_with('.') { + if let Some('.') = rest[1..].chars().next() { + try!(f.write_str("::")); + rest = &rest[2..]; + } else { + try!(f.write_str(".")); + rest = &rest[1..]; + } + } else if rest.starts_with('$') { + macro_rules! demangle { + ($($pat:expr => $demangled:expr),*) => ({ + $(if rest.starts_with($pat) { + try!(f.write_str($demangled)); + rest = &rest[$pat.len()..]; + } else)* + { + try!(f.write_str(rest)); + break; + } + + }) + } + + // see src/librustc/back/link.rs for these mappings + demangle! { + "$SP$" => "@", + "$BP$" => "*", + "$RF$" => "&", + "$LT$" => "<", + "$GT$" => ">", + "$LP$" => "(", + "$RP$" => ")", + "$C$" => ",", + + // in theory we can demangle any Unicode code point, but + // for simplicity we just catch the common ones. + "$u7e$" => "~", + "$u20$" => " ", + "$u27$" => "'", + "$u5b$" => "[", + "$u5d$" => "]", + "$u7b$" => "{", + "$u7d$" => "}", + "$u3b$" => ";", + "$u2b$" => "+", + "$u22$" => "\"" + } + } else { + let idx = match rest.char_indices().find(|&(_, c)| c == '$' || c == '.') { + None => rest.len(), + Some((i, _)) => i, + }; + try!(f.write_str(&rest[..idx])); + rest = &rest[idx..]; + } + } + } + + Ok(()) + } +} + +impl<'a> fmt::Debug for Demangle<'a> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + fmt::Display::fmt(self, f) + } +} + +#[cfg(test)] +mod tests { + use std::prelude::v1::*; + + macro_rules! t { + ($a:expr, $b:expr) => ({ + assert_eq!(super::demangle($a).to_string(), $b); + }) + } + + macro_rules! t_nohash { + ($a:expr, $b:expr) => ({ + assert_eq!(format!("{:#}", super::demangle($a)), $b); + }) + } + + #[test] + fn demangle() { + t!("test", "test"); + t!("_ZN4testE", "test"); + t!("_ZN4test", "_ZN4test"); + t!("_ZN4test1a2bcE", "test::a::bc"); + } + + #[test] + fn demangle_dollars() { + t!("_ZN4$RP$E", ")"); + t!("_ZN8$RF$testE", "&test"); + t!("_ZN8$BP$test4foobE", "*test::foob"); + t!("_ZN9$u20$test4foobE", " test::foob"); + t!("_ZN35Bar$LT$$u5b$u32$u3b$$u20$4$u5d$$GT$E", "Bar<[u32; 4]>"); + } + + #[test] + fn demangle_many_dollars() { + t!("_ZN13test$u20$test4foobE", "test test::foob"); + t!("_ZN12test$BP$test4foobE", "test*test::foob"); + } + + + #[test] + fn demangle_osx() { + t!("__ZN5alloc9allocator6Layout9for_value17h02a996811f781011E", "alloc::allocator::Layout::for_value::h02a996811f781011"); + t!("__ZN38_$LT$core..option..Option$LT$T$GT$$GT$6unwrap18_MSG_FILE_LINE_COL17haf7cb8d5824ee659E", "<core::option::Option<T>>::unwrap::_MSG_FILE_LINE_COL::haf7cb8d5824ee659"); + t!("__ZN4core5slice89_$LT$impl$u20$core..iter..traits..IntoIterator$u20$for$u20$$RF$$u27$a$u20$$u5b$T$u5d$$GT$9into_iter17h450e234d27262170E", "core::slice::<impl core::iter::traits::IntoIterator for &'a [T]>::into_iter::h450e234d27262170"); + } + + #[test] + fn demangle_windows() { + t!("ZN4testE", "test"); + t!("ZN13test$u20$test4foobE", "test test::foob"); + t!("ZN12test$RF$test4foobE", "test&test::foob"); + } + + #[test] + fn demangle_elements_beginning_with_underscore() { + t!("_ZN13_$LT$test$GT$E", "<test>"); + t!("_ZN28_$u7b$$u7b$closure$u7d$$u7d$E", "{{closure}}"); + t!("_ZN15__STATIC_FMTSTRE", "__STATIC_FMTSTR"); + } + + #[test] + fn demangle_trait_impls() { + t!("_ZN71_$LT$Test$u20$$u2b$$u20$$u27$static$u20$as$u20$foo..Bar$LT$Test$GT$$GT$3barE", + "<Test + 'static as foo::Bar<Test>>::bar"); + } + + #[test] + fn demangle_without_hash() { + let s = "_ZN3foo17h05af221e174051e9E"; + t!(s, "foo::h05af221e174051e9"); + t_nohash!(s, "foo"); + } + + #[test] + fn demangle_without_hash_edgecases() { + // One element, no hash. + t_nohash!("_ZN3fooE", "foo"); + // Two elements, no hash. + t_nohash!("_ZN3foo3barE", "foo::bar"); + // Longer-than-normal hash. + t_nohash!("_ZN3foo20h05af221e174051e9abcE", "foo"); + // Shorter-than-normal hash. + t_nohash!("_ZN3foo5h05afE", "foo"); + // Valid hash, but not at the end. + t_nohash!("_ZN17h05af221e174051e93fooE", "h05af221e174051e9::foo"); + // Not a valid hash, missing the 'h'. + t_nohash!("_ZN3foo16ffaf221e174051e9E", "foo::ffaf221e174051e9"); + // Not a valid hash, has a non-hex-digit. + t_nohash!("_ZN3foo17hg5af221e174051e9E", "foo::hg5af221e174051e9"); + } + + #[test] + fn demangle_thinlto() { + // One element, no hash. + t!("_ZN3fooE.llvm.9D1C9369", "foo"); + t!("_ZN3fooE.llvm.9D1C9369@@16", "foo"); + t_nohash!("_ZN9backtrace3foo17hbb467fcdaea5d79bE.llvm.A5310EB9", "backtrace::foo"); + } + + #[test] + fn dont_panic() { + super::demangle("_ZN2222222222222222222222EE").to_string(); + super::demangle("_ZN5*70527e27.ll34csaғE").to_string(); + super::demangle("_ZN5*70527a54.ll34_$b.1E").to_string(); + super::demangle("\ + _ZN5~saäb4e\n\ + 2734cOsbE\n\ + 5usage20h)3\0\0\0\0\0\0\07e2734cOsbE\ + ").to_string(); + } +} |