use std::prelude::v1::*;
use std::fmt;
use std::mem;
use std::path::{Path, PathBuf};
use {trace, resolve, SymbolName};
use types::c_void;
/// Representation of an owned and self-contained backtrace.
///
/// This structure can be used to capture a backtrace at various points in a
/// program and later used to inspect what the backtrace was at that time.
///
/// `Backtrace` supports pretty-printing of backtraces by implementing
/// `Display` and `Debug` (which do the same thing).
#[derive(Clone)]
#[cfg_attr(feature = "serialize-rustc", derive(RustcDecodable, RustcEncodable))]
#[cfg_attr(feature = "serialize-serde", derive(Deserialize, Serialize))]
pub struct Backtrace {
// Frames here are listed from top-to-bottom of the stack
frames: Vec<BacktraceFrame>,
// The index we believe is the actual start of the backtrace, omitting
// frames like `Backtrace::new` and `backtrace::trace`.
actual_start_index: usize,
}
/// Captured version of a frame in a backtrace.
///
/// This type is returned as a list from `Backtrace::frames` and represents one
/// stack frame in a captured backtrace.
#[derive(Clone)]
#[cfg_attr(feature = "serialize-rustc", derive(RustcDecodable, RustcEncodable))]
#[cfg_attr(feature = "serialize-serde", derive(Deserialize, Serialize))]
pub struct BacktraceFrame {
ip: usize,
symbol_address: usize,
symbols: Option<Vec<BacktraceSymbol>>,
}
/// Captured version of a symbol in a backtrace.
///
/// This type is returned as a list from `BacktraceFrame::symbols` and
/// represents the metadata for a symbol in a backtrace.
#[derive(Clone)]
#[cfg_attr(feature = "serialize-rustc", derive(RustcDecodable, RustcEncodable))]
#[cfg_attr(feature = "serialize-serde", derive(Deserialize, Serialize))]
pub struct BacktraceSymbol {
name: Option<Vec<u8>>,
addr: Option<usize>,
filename: Option<PathBuf>,
lineno: Option<u32>,
}
impl Backtrace {
/// Captures a backtrace at the callsite of this function, returning an
/// owned representation.
///
/// This function is useful for representing a backtrace as an object in
/// Rust. This returned value can be sent across threads and printed
/// elsewhere, and the purpose of this value is to be entirely self
/// contained.
///
/// # Examples
///
/// ```
/// use backtrace::Backtrace;
///
/// let current_backtrace = Backtrace::new();
/// ```
#[inline(never)] // want to make sure there's a frame here to remove
pub fn new() -> Backtrace {
let mut bt = Self::create(Self::new as usize);
bt.resolve();
bt
}
/// Similar to `new` except that this does not resolve any symbols, this
/// simply captures the backtrace as a list of addresses.
///
/// At a later time the `resolve` function can be called to resolve this
/// backtrace's symbols into readable names. This function exists because
/// the resolution process can sometimes take a significant amount of time
/// whereas any one backtrace may only be rarely printed.
///
/// # Examples
///
/// ```
/// use backtrace::Backtrace;
///
/// let mut current_backtrace = Backtrace::new_unresolved();
/// println!("{:?}", current_backtrace); // no symbol names
/// current_backtrace.resolve();
/// println!("{:?}", current_backtrace); // symbol names now present
/// ```
#[inline(never)] // want to make sure there's a frame here to remove
pub fn new_unresolved() -> Backtrace {
Self::create(Self::new_unresolved as usize)
}
fn create(ip: usize) -> Backtrace {
let ip_lo = ip;
let ip_hi = ip + 128;
let mut frames = Vec::new();
let mut actual_start_index = None;
trace(|frame| {
let ip = frame.ip() as usize;
frames.push(BacktraceFrame {
ip,
symbol_address: frame.symbol_address() as usize,
symbols: None,
});
if cfg!(not(all(target_os = "windows", target_arch = "x86"))) &&
ip >= ip_lo &&
ip <= ip_hi &&
actual_start_index.is_none()
{
actual_start_index = Some(frames.len());
}
true
});
Backtrace {
frames,
actual_start_index: actual_start_index.unwrap_or(0),
}
}
/// Returns the frames from when this backtrace was captured.
///
/// The first entry of this slice is likely the function `Backtrace::new`,
/// and the last frame is likely something about how this thread or the main
/// function started.
pub fn frames(&self) -> &[BacktraceFrame] {
&self.frames[self.actual_start_index..]
}
/// If this backtrace was created from `new_unresolved` then this function
/// will resolve all addresses in the backtrace to their symbolic names.
///
/// If this backtrace has been previously resolved or was created through
/// `new`, this function does nothing.
pub fn resolve(&mut self) {
for frame in self.frames.iter_mut().filter(|f| f.symbols.is_none()) {
let mut symbols = Vec::new();
resolve(frame.ip as *mut _, |symbol| {
symbols.push(BacktraceSymbol {
name: symbol.name().map(|m| m.as_bytes().to_vec()),
addr: symbol.addr().map(|a| a as usize),
filename: symbol.filename().map(|m| m.to_owned()),
lineno: symbol.lineno(),
});
});
frame.symbols = Some(symbols);
}
}
}
impl From<Vec<BacktraceFrame>> for Backtrace {
fn from(frames: Vec<BacktraceFrame>) -> Self {
Backtrace {
frames,
actual_start_index: 0,
}
}
}
impl Into<Vec<BacktraceFrame>> for Backtrace {
fn into(self) -> Vec<BacktraceFrame> {
self.frames
}
}
impl BacktraceFrame {
/// Same as `Frame::ip`
pub fn ip(&self) -> *mut c_void {
self.ip as *mut c_void
}
/// Same as `Frame::symbol_address`
pub fn symbol_address(&self) -> *mut c_void {
self.symbol_address as *mut c_void
}
/// Returns the list of symbols that this frame corresponds to.
///
/// Normally there is only one symbol per frame, but sometimes if a number
/// of functions are inlined into one frame then multiple symbols will be
/// returned. The first symbol listed is the "innermost function", whereas
/// the last symbol is the outermost (last caller).
///
/// Note that if this frame came from an unresolved backtrace then this will
/// return an empty list.
pub fn symbols(&self) -> &[BacktraceSymbol] {
self.symbols.as_ref().map(|s| &s[..]).unwrap_or(&[])
}
}
impl BacktraceSymbol {
/// Same as `Symbol::name`
pub fn name(&self) -> Option<SymbolName> {
self.name.as_ref().map(|s| SymbolName::new(s))
}
/// Same as `Symbol::addr`
pub fn addr(&self) -> Option<*mut c_void> {
self.addr.map(|s| s as *mut c_void)
}
/// Same as `Symbol::filename`
pub fn filename(&self) -> Option<&Path> {
self.filename.as_ref().map(|p| &**p)
}
/// Same as `Symbol::lineno`
pub fn lineno(&self) -> Option<u32> {
self.lineno
}
}
impl fmt::Debug for Backtrace {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
let hex_width = mem::size_of::<usize>() * 2 + 2;
write!(fmt, "stack backtrace:")?;
let iter = if fmt.alternate() {
self.frames.iter()
} else {
self.frames[self.actual_start_index..].iter()
};
for (idx, frame) in iter.enumerate() {
let ip = frame.ip();
write!(fmt, "\n{:4}: ", idx)?;
let symbols = match frame.symbols {
Some(ref s) => s,
None => {
write!(fmt, "<unresolved> ({:?})", ip)?;
continue
}
};
if symbols.len() == 0 {
write!(fmt, "<no info> ({:?})", ip)?;
continue;
}
for (idx, symbol) in symbols.iter().enumerate() {
if idx != 0 {
write!(fmt, "\n ")?;
}
if let Some(name) = symbol.name() {
write!(fmt, "{}", name)?;
} else {
write!(fmt, "<unknown>")?;
}
if idx == 0 {
write!(fmt, " ({:?})", ip)?;
}
if let (Some(file), Some(line)) = (symbol.filename(), symbol.lineno()) {
write!(fmt, "\n at {}:{}", file.display(), line)?;
}
}
}
Ok(())
}
}
impl fmt::Display for Backtrace {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(self, fmt)
}
}
impl Default for Backtrace {
fn default() -> Backtrace {
Backtrace::new()
}
}