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use core::char;
use core::fmt;
/// Representation of a demangled symbol name.
pub struct Demangle<'a> {
inner: &'a str,
/// 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 and return a value. When printed,
/// the de-mangled version will be written. If the symbol does not look like
/// a mangled symbol, the original value will be written instead.
///
/// # 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(s: &str) -> Result<(Demangle, &str), ()> {
// 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 inner = if s.starts_with("_ZN") {
&s[3..]
} else if s.starts_with("ZN") {
// On Windows, dbghelp strips leading underscores, so we accept "ZN...E"
// form too.
&s[2..]
} else if s.starts_with("__ZN") {
// On OSX, symbols are prefixed with an extra _
&s[4..]
} else {
return Err(());
};
// only work with ascii text
if inner.bytes().any(|c| c & 0x80 != 0) {
return Err(());
}
let mut elements = 0;
let mut chars = inner.chars();
let mut c = chars.next().ok_or(())?;
while c != 'E' {
// Decode an identifier element's length.
if !c.is_digit(10) {
return Err(());
}
let mut len = 0usize;
while let Some(d) = c.to_digit(10) {
len = len
.checked_mul(10)
.and_then(|len| len.checked_add(d as usize))
.ok_or(())?;
c = chars.next().ok_or(())?;
}
// `c` already contains the first character of this identifier, skip it and
// all the other characters of this identifier, to reach the next element.
for _ in 0..len {
c = chars.next().ok_or(())?;
}
elements += 1;
}
Ok((Demangle { inner, elements }, chars.as_str()))
}
// 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.
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 {
f.write_str("::")?;
}
if rest.starts_with("_$") {
rest = &rest[1..];
}
loop {
if rest.starts_with('.') {
if let Some('.') = rest[1..].chars().next() {
f.write_str("::")?;
rest = &rest[2..];
} else {
f.write_str(".")?;
rest = &rest[1..];
}
} else if rest.starts_with('$') {
let (escape, after_escape) = if let Some(end) = rest[1..].find('$') {
(&rest[1..=end], &rest[end + 2..])
} else {
break;
};
// see src/librustc_codegen_utils/symbol_names/legacy.rs for these mappings
let unescaped = match escape {
"SP" => "@",
"BP" => "*",
"RF" => "&",
"LT" => "<",
"GT" => ">",
"LP" => "(",
"RP" => ")",
"C" => ",",
_ => {
if escape.starts_with('u') {
let digits = &escape[1..];
let all_lower_hex = digits.chars().all(|c| match c {
'0'..='9' | 'a'..='f' => true,
_ => false,
});
let c = u32::from_str_radix(digits, 16)
.ok()
.and_then(char::from_u32);
if let (true, Some(c)) = (all_lower_hex, c) {
// FIXME(eddyb) do we need to filter out control codepoints?
if !c.is_control() {
c.fmt(f)?;
rest = after_escape;
continue;
}
}
}
break;
}
};
f.write_str(unescaped)?;
rest = after_escape;
} else if let Some(i) = rest.find(|c| c == '$' || c == '.') {
f.write_str(&rest[..i])?;
rest = &rest[i..];
} else {
break;
}
}
f.write_str(rest)?;
}
Ok(())
}
}
#[cfg(test)]
mod tests {
use std::prelude::v1::*;
macro_rules! t {
($a:expr, $b:expr) => {
assert!(ok($a, $b))
};
}
macro_rules! t_err {
($a:expr) => {
assert!(ok_err($a))
};
}
macro_rules! t_nohash {
($a:expr, $b:expr) => {{
assert_eq!(format!("{:#}", ::demangle($a)), $b);
}};
}
fn ok(sym: &str, expected: &str) -> bool {
match ::try_demangle(sym) {
Ok(s) => {
if s.to_string() == expected {
true
} else {
println!("\n{}\n!=\n{}\n", s, expected);
false
}
}
Err(_) => {
println!("error demangling");
false
}
}
}
fn ok_err(sym: &str) -> bool {
match ::try_demangle(sym) {
Ok(_) => {
println!("succeeded in demangling");
false
}
Err(_) => ::demangle(sym).to_string() == sym,
}
}
#[test]
fn demangle() {
t_err!("test");
t!("_ZN4testE", "test");
t_err!("_ZN4test");
t!("_ZN4test1a2bcE", "test::a::bc");
}
#[test]
fn demangle_dollars() {
t!("_ZN4$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$3barE",
"<Test + 'static as foo::Bar<Test>>::bar"
);
}
#[test]
fn demangle_without_hash() {
let s = "_ZN3foo17h05af221e174051e9E";
t!(s, "foo::h05af221e174051e9");
t_nohash!(s, "foo");
}
#[test]
fn demangle_without_hash_edgecases() {
// One element, no hash.
t_nohash!("_ZN3fooE", "foo");
// Two elements, no hash.
t_nohash!("_ZN3foo3barE", "foo::bar");
// Longer-than-normal hash.
t_nohash!("_ZN3foo20h05af221e174051e9abcE", "foo");
// Shorter-than-normal hash.
t_nohash!("_ZN3foo5h05afE", "foo");
// Valid hash, but not at the end.
t_nohash!("_ZN17h05af221e174051e93fooE", "h05af221e174051e9::foo");
// Not a valid hash, missing the 'h'.
t_nohash!("_ZN3foo16ffaf221e174051e9E", "foo::ffaf221e174051e9");
// Not a valid hash, has a non-hex-digit.
t_nohash!("_ZN3foo17hg5af221e174051e9E", "foo::hg5af221e174051e9");
}
#[test]
fn demangle_thinlto() {
// One element, no hash.
t!("_ZN3fooE.llvm.9D1C9369", "foo");
t!("_ZN3fooE.llvm.9D1C9369@@16", "foo");
t_nohash!(
"_ZN9backtrace3foo17hbb467fcdaea5d79bE.llvm.A5310EB9",
"backtrace::foo"
);
}
#[test]
fn demangle_llvm_ir_branch_labels() {
t!("_ZN4core5slice77_$LT$impl$u20$core..ops..index..IndexMut$LT$I$GT$$u20$for$u20$$u5b$T$u5d$$GT$9index_mut17haf9727c2edfbc47bE.exit.i.i", "core::slice::<impl core::ops::index::IndexMut<I> for [T]>::index_mut::haf9727c2edfbc47b.exit.i.i");
t_nohash!("_ZN4core5slice77_$LT$impl$u20$core..ops..index..IndexMut$LT$I$GT$$u20$for$u20$$u5b$T$u5d$$GT$9index_mut17haf9727c2edfbc47bE.exit.i.i", "core::slice::<impl core::ops::index::IndexMut<I> for [T]>::index_mut.exit.i.i");
}
#[test]
fn demangle_ignores_suffix_that_doesnt_look_like_a_symbol() {
t_err!("_ZN3fooE.llvm moocow");
}
#[test]
fn dont_panic() {
::demangle("_ZN2222222222222222222222EE").to_string();
::demangle("_ZN5*70527e27.ll34csaғE").to_string();
::demangle("_ZN5*70527a54.ll34_$b.1E").to_string();
::demangle(
"\
_ZN5~saäb4e\n\
2734cOsbE\n\
5usage20h)3\0\0\0\0\0\0\07e2734cOsbE\
",
)
.to_string();
}
#[test]
fn invalid_no_chop() {
t_err!("_ZNfooE");
}
#[test]
fn handle_assoc_types() {
t!("_ZN151_$LT$alloc..boxed..Box$LT$alloc..boxed..FnBox$LT$A$C$$u20$Output$u3d$R$GT$$u20$$u2b$$u20$$u27$a$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$9call_once17h69e8f44b3723e1caE", "<alloc::boxed::Box<alloc::boxed::FnBox<A, Output=R> + 'a> as core::ops::function::FnOnce<A>>::call_once::h69e8f44b3723e1ca");
}
#[test]
fn handle_bang() {
t!(
"_ZN88_$LT$core..result..Result$LT$$u21$$C$$u20$E$GT$$u20$as$u20$std..process..Termination$GT$6report17hfc41d0da4a40b3e8E",
"<core::result::Result<!, E> as std::process::Termination>::report::hfc41d0da4a40b3e8"
);
}
#[test]
fn demangle_utf8_idents() {
t_nohash!(
"_ZN11utf8_idents157_$u10e1$$u10d0$$u10ed$$u10db$$u10d4$$u10da$$u10d0$$u10d3$_$u10d2$$u10d4$$u10db$$u10e0$$u10d8$$u10d4$$u10da$$u10d8$_$u10e1$$u10d0$$u10d3$$u10d8$$u10da$$u10d8$17h21634fd5714000aaE",
"utf8_idents::საჭმელად_გემრიელი_სადილი"
);
}
#[test]
fn demangle_issue_60925() {
t_nohash!(
"_ZN11issue_609253foo37Foo$LT$issue_60925..llv$u6d$..Foo$GT$3foo17h059a991a004536adE",
"issue_60925::foo::Foo<issue_60925::llvm::Foo>::foo"
);
}
}