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-rw-r--r--library/backtrace/src/symbolize/mod.rs485
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diff --git a/library/backtrace/src/symbolize/mod.rs b/library/backtrace/src/symbolize/mod.rs
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+use core::{fmt, str};
+
+cfg_if::cfg_if! {
+ if #[cfg(feature = "std")] {
+ use std::path::Path;
+ use std::prelude::v1::*;
+ }
+}
+
+use super::backtrace::Frame;
+use super::types::BytesOrWideString;
+use core::ffi::c_void;
+use rustc_demangle::{try_demangle, Demangle};
+
+/// Resolve an address to a symbol, passing the symbol to the specified
+/// closure.
+///
+/// This function will look up the given address in areas such as the local
+/// symbol table, dynamic symbol table, or DWARF debug info (depending on the
+/// activated implementation) to find symbols to yield.
+///
+/// The closure may not be called if resolution could not be performed, and it
+/// also may be called more than once in the case of inlined functions.
+///
+/// Symbols yielded represent the execution at the specified `addr`, returning
+/// file/line pairs for that address (if available).
+///
+/// Note that if you have a `Frame` then it's recommended to use the
+/// `resolve_frame` function instead of this one.
+///
+/// # Required features
+///
+/// This function requires the `std` feature of the `backtrace` crate to be
+/// enabled, and the `std` feature is enabled by default.
+///
+/// # Panics
+///
+/// This function strives to never panic, but if the `cb` provided panics then
+/// some platforms will force a double panic to abort the process. Some
+/// platforms use a C library which internally uses callbacks which cannot be
+/// unwound through, so panicking from `cb` may trigger a process abort.
+///
+/// # Example
+///
+/// ```
+/// extern crate backtrace;
+///
+/// fn main() {
+/// backtrace::trace(|frame| {
+/// let ip = frame.ip();
+///
+/// backtrace::resolve(ip, |symbol| {
+/// // ...
+/// });
+///
+/// false // only look at the top frame
+/// });
+/// }
+/// ```
+#[cfg(feature = "std")]
+pub fn resolve<F: FnMut(&Symbol)>(addr: *mut c_void, cb: F) {
+ let _guard = crate::lock::lock();
+ unsafe { resolve_unsynchronized(addr, cb) }
+}
+
+/// Resolve a previously capture frame to a symbol, passing the symbol to the
+/// specified closure.
+///
+/// This function performs the same function as `resolve` except that it takes a
+/// `Frame` as an argument instead of an address. This can allow some platform
+/// implementations of backtracing to provide more accurate symbol information
+/// or information about inline frames for example. It's recommended to use this
+/// if you can.
+///
+/// # Required features
+///
+/// This function requires the `std` feature of the `backtrace` crate to be
+/// enabled, and the `std` feature is enabled by default.
+///
+/// # Panics
+///
+/// This function strives to never panic, but if the `cb` provided panics then
+/// some platforms will force a double panic to abort the process. Some
+/// platforms use a C library which internally uses callbacks which cannot be
+/// unwound through, so panicking from `cb` may trigger a process abort.
+///
+/// # Example
+///
+/// ```
+/// extern crate backtrace;
+///
+/// fn main() {
+/// backtrace::trace(|frame| {
+/// backtrace::resolve_frame(frame, |symbol| {
+/// // ...
+/// });
+///
+/// false // only look at the top frame
+/// });
+/// }
+/// ```
+#[cfg(feature = "std")]
+pub fn resolve_frame<F: FnMut(&Symbol)>(frame: &Frame, cb: F) {
+ let _guard = crate::lock::lock();
+ unsafe { resolve_frame_unsynchronized(frame, cb) }
+}
+
+pub enum ResolveWhat<'a> {
+ Address(*mut c_void),
+ Frame(&'a Frame),
+}
+
+impl<'a> ResolveWhat<'a> {
+ #[allow(dead_code)]
+ fn address_or_ip(&self) -> *mut c_void {
+ match self {
+ ResolveWhat::Address(a) => adjust_ip(*a),
+ ResolveWhat::Frame(f) => adjust_ip(f.ip()),
+ }
+ }
+}
+
+// IP values from stack frames are typically (always?) the instruction
+// *after* the call that's the actual stack trace. Symbolizing this on
+// causes the filename/line number to be one ahead and perhaps into
+// the void if it's near the end of the function.
+//
+// This appears to basically always be the case on all platforms, so we always
+// subtract one from a resolved ip to resolve it to the previous call
+// instruction instead of the instruction being returned to.
+//
+// Ideally we would not do this. Ideally we would require callers of the
+// `resolve` APIs here to manually do the -1 and account that they want location
+// information for the *previous* instruction, not the current. Ideally we'd
+// also expose on `Frame` if we are indeed the address of the next instruction
+// or the current.
+//
+// For now though this is a pretty niche concern so we just internally always
+// subtract one. Consumers should keep working and getting pretty good results,
+// so we should be good enough.
+fn adjust_ip(a: *mut c_void) -> *mut c_void {
+ if a.is_null() {
+ a
+ } else {
+ (a as usize - 1) as *mut c_void
+ }
+}
+
+/// Same as `resolve`, only unsafe as it's unsynchronized.
+///
+/// This function does not have synchronization guarantees but is available when
+/// the `std` feature of this crate isn't compiled in. See the `resolve`
+/// function for more documentation and examples.
+///
+/// # Panics
+///
+/// See information on `resolve` for caveats on `cb` panicking.
+pub unsafe fn resolve_unsynchronized<F>(addr: *mut c_void, mut cb: F)
+where
+ F: FnMut(&Symbol),
+{
+ imp::resolve(ResolveWhat::Address(addr), &mut cb)
+}
+
+/// Same as `resolve_frame`, only unsafe as it's unsynchronized.
+///
+/// This function does not have synchronization guarantees but is available
+/// when the `std` feature of this crate isn't compiled in. See the
+/// `resolve_frame` function for more documentation and examples.
+///
+/// # Panics
+///
+/// See information on `resolve_frame` for caveats on `cb` panicking.
+pub unsafe fn resolve_frame_unsynchronized<F>(frame: &Frame, mut cb: F)
+where
+ F: FnMut(&Symbol),
+{
+ imp::resolve(ResolveWhat::Frame(frame), &mut cb)
+}
+
+/// A trait representing the resolution of a symbol in a file.
+///
+/// This trait is yielded as a trait object to the closure given to the
+/// `backtrace::resolve` function, and it is virtually dispatched as it's
+/// unknown which implementation is behind it.
+///
+/// A symbol can give contextual information about a function, for example the
+/// name, filename, line number, precise address, etc. Not all information is
+/// always available in a symbol, however, so all methods return an `Option`.
+pub struct Symbol {
+ // TODO: this lifetime bound needs to be persisted eventually to `Symbol`,
+ // but that's currently a breaking change. For now this is safe since
+ // `Symbol` is only ever handed out by reference and can't be cloned.
+ inner: imp::Symbol<'static>,
+}
+
+impl Symbol {
+ /// Returns the name of this function.
+ ///
+ /// The returned structure can be used to query various properties about the
+ /// symbol name:
+ ///
+ /// * The `Display` implementation will print out the demangled symbol.
+ /// * The raw `str` value of the symbol can be accessed (if it's valid
+ /// utf-8).
+ /// * The raw bytes for the symbol name can be accessed.
+ pub fn name(&self) -> Option<SymbolName<'_>> {
+ self.inner.name()
+ }
+
+ /// Returns the starting address of this function.
+ pub fn addr(&self) -> Option<*mut c_void> {
+ self.inner.addr().map(|p| p as *mut _)
+ }
+
+ /// Returns the raw filename as a slice. This is mainly useful for `no_std`
+ /// environments.
+ pub fn filename_raw(&self) -> Option<BytesOrWideString<'_>> {
+ self.inner.filename_raw()
+ }
+
+ /// Returns the column number for where this symbol is currently executing.
+ ///
+ /// Only gimli currently provides a value here and even then only if `filename`
+ /// returns `Some`, and so it is then consequently subject to similar caveats.
+ pub fn colno(&self) -> Option<u32> {
+ self.inner.colno()
+ }
+
+ /// Returns the line number for where this symbol is currently executing.
+ ///
+ /// This return value is typically `Some` if `filename` returns `Some`, and
+ /// is consequently subject to similar caveats.
+ pub fn lineno(&self) -> Option<u32> {
+ self.inner.lineno()
+ }
+
+ /// Returns the file name where this function was defined.
+ ///
+ /// This is currently only available when libbacktrace or gimli is being
+ /// used (e.g. unix platforms other) and when a binary is compiled with
+ /// debuginfo. If neither of these conditions is met then this will likely
+ /// return `None`.
+ ///
+ /// # Required features
+ ///
+ /// This function requires the `std` feature of the `backtrace` crate to be
+ /// enabled, and the `std` feature is enabled by default.
+ #[cfg(feature = "std")]
+ #[allow(unreachable_code)]
+ pub fn filename(&self) -> Option<&Path> {
+ self.inner.filename()
+ }
+}
+
+impl fmt::Debug for Symbol {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ let mut d = f.debug_struct("Symbol");
+ if let Some(name) = self.name() {
+ d.field("name", &name);
+ }
+ if let Some(addr) = self.addr() {
+ d.field("addr", &addr);
+ }
+
+ #[cfg(feature = "std")]
+ {
+ if let Some(filename) = self.filename() {
+ d.field("filename", &filename);
+ }
+ }
+
+ if let Some(lineno) = self.lineno() {
+ d.field("lineno", &lineno);
+ }
+ d.finish()
+ }
+}
+
+cfg_if::cfg_if! {
+ if #[cfg(feature = "cpp_demangle")] {
+ // Maybe a parsed C++ symbol, if parsing the mangled symbol as Rust
+ // failed.
+ struct OptionCppSymbol<'a>(Option<::cpp_demangle::BorrowedSymbol<'a>>);
+
+ impl<'a> OptionCppSymbol<'a> {
+ fn parse(input: &'a [u8]) -> OptionCppSymbol<'a> {
+ OptionCppSymbol(::cpp_demangle::BorrowedSymbol::new(input).ok())
+ }
+
+ fn none() -> OptionCppSymbol<'a> {
+ OptionCppSymbol(None)
+ }
+ }
+ } else {
+ use core::marker::PhantomData;
+
+ // Make sure to keep this zero-sized, so that the `cpp_demangle` feature
+ // has no cost when disabled.
+ struct OptionCppSymbol<'a>(PhantomData<&'a ()>);
+
+ impl<'a> OptionCppSymbol<'a> {
+ fn parse(_: &'a [u8]) -> OptionCppSymbol<'a> {
+ OptionCppSymbol(PhantomData)
+ }
+
+ fn none() -> OptionCppSymbol<'a> {
+ OptionCppSymbol(PhantomData)
+ }
+ }
+ }
+}
+
+/// A wrapper around a symbol name to provide ergonomic accessors to the
+/// demangled name, the raw bytes, the raw string, etc.
+// Allow dead code for when the `cpp_demangle` feature is not enabled.
+#[allow(dead_code)]
+pub struct SymbolName<'a> {
+ bytes: &'a [u8],
+ demangled: Option<Demangle<'a>>,
+ cpp_demangled: OptionCppSymbol<'a>,
+}
+
+impl<'a> SymbolName<'a> {
+ /// Creates a new symbol name from the raw underlying bytes.
+ pub fn new(bytes: &'a [u8]) -> SymbolName<'a> {
+ let str_bytes = str::from_utf8(bytes).ok();
+ let demangled = str_bytes.and_then(|s| try_demangle(s).ok());
+
+ let cpp = if demangled.is_none() {
+ OptionCppSymbol::parse(bytes)
+ } else {
+ OptionCppSymbol::none()
+ };
+
+ SymbolName {
+ bytes: bytes,
+ demangled: demangled,
+ cpp_demangled: cpp,
+ }
+ }
+
+ /// Returns the raw (mangled) symbol name as a `str` if the symbol is valid utf-8.
+ ///
+ /// Use the `Display` implementation if you want the demangled version.
+ pub fn as_str(&self) -> Option<&'a str> {
+ self.demangled
+ .as_ref()
+ .map(|s| s.as_str())
+ .or_else(|| str::from_utf8(self.bytes).ok())
+ }
+
+ /// Returns the raw symbol name as a list of bytes
+ pub fn as_bytes(&self) -> &'a [u8] {
+ self.bytes
+ }
+}
+
+fn format_symbol_name(
+ fmt: fn(&str, &mut fmt::Formatter<'_>) -> fmt::Result,
+ mut bytes: &[u8],
+ f: &mut fmt::Formatter<'_>,
+) -> fmt::Result {
+ while bytes.len() > 0 {
+ match str::from_utf8(bytes) {
+ Ok(name) => {
+ fmt(name, f)?;
+ break;
+ }
+ Err(err) => {
+ fmt("\u{FFFD}", f)?;
+
+ match err.error_len() {
+ Some(len) => bytes = &bytes[err.valid_up_to() + len..],
+ None => break,
+ }
+ }
+ }
+ }
+ Ok(())
+}
+
+cfg_if::cfg_if! {
+ if #[cfg(feature = "cpp_demangle")] {
+ impl<'a> fmt::Display for SymbolName<'a> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ if let Some(ref s) = self.demangled {
+ s.fmt(f)
+ } else if let Some(ref cpp) = self.cpp_demangled.0 {
+ cpp.fmt(f)
+ } else {
+ format_symbol_name(fmt::Display::fmt, self.bytes, f)
+ }
+ }
+ }
+ } else {
+ impl<'a> fmt::Display for SymbolName<'a> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ if let Some(ref s) = self.demangled {
+ s.fmt(f)
+ } else {
+ format_symbol_name(fmt::Display::fmt, self.bytes, f)
+ }
+ }
+ }
+ }
+}
+
+cfg_if::cfg_if! {
+ if #[cfg(all(feature = "std", feature = "cpp_demangle"))] {
+ impl<'a> fmt::Debug for SymbolName<'a> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ use std::fmt::Write;
+
+ if let Some(ref s) = self.demangled {
+ return s.fmt(f)
+ }
+
+ // This may to print if the demangled symbol isn't actually
+ // valid, so handle the error here gracefully by not propagating
+ // it outwards.
+ if let Some(ref cpp) = self.cpp_demangled.0 {
+ let mut s = String::new();
+ if write!(s, "{}", cpp).is_ok() {
+ return s.fmt(f)
+ }
+ }
+
+ format_symbol_name(fmt::Debug::fmt, self.bytes, f)
+ }
+ }
+ } else {
+ impl<'a> fmt::Debug for SymbolName<'a> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ if let Some(ref s) = self.demangled {
+ s.fmt(f)
+ } else {
+ format_symbol_name(fmt::Debug::fmt, self.bytes, f)
+ }
+ }
+ }
+ }
+}
+
+/// Attempt to reclaim that cached memory used to symbolicate addresses.
+///
+/// This method will attempt to release any global data structures that have
+/// otherwise been cached globally or in the thread which typically represent
+/// parsed DWARF information or similar.
+///
+/// # Caveats
+///
+/// While this function is always available it doesn't actually do anything on
+/// most implementations. Libraries like dbghelp or libbacktrace do not provide
+/// facilities to deallocate state and manage the allocated memory. For now the
+/// `gimli-symbolize` feature of this crate is the only feature where this
+/// function has any effect.
+#[cfg(feature = "std")]
+pub fn clear_symbol_cache() {
+ let _guard = crate::lock::lock();
+ unsafe {
+ imp::clear_symbol_cache();
+ }
+}
+
+cfg_if::cfg_if! {
+ if #[cfg(miri)] {
+ mod miri;
+ use miri as imp;
+ } else if #[cfg(all(windows, target_env = "msvc", not(target_vendor = "uwp")))] {
+ mod dbghelp;
+ use dbghelp as imp;
+ } else if #[cfg(all(
+ any(unix, windows),
+ not(target_vendor = "uwp"),
+ not(target_os = "emscripten"),
+ any(not(backtrace_in_libstd), feature = "backtrace"),
+ ))] {
+ mod gimli;
+ use gimli as imp;
+ } else {
+ mod noop;
+ use noop as imp;
+ }
+}
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