1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
use crate::PrintFmt;
use crate::{resolve, resolve_frame, trace, BacktraceFmt, Symbol, SymbolName};
use std::ffi::c_void;
use std::fmt;
use std::path::{Path, PathBuf};
use std::prelude::v1::*;

#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

/// 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 through its `Debug`
/// implementation.
///
/// # Required features
///
/// This function requires the `std` feature of the `backtrace` crate to be
/// enabled, and the `std` feature is enabled by default.
#[derive(Clone)]
#[cfg_attr(feature = "serialize-rustc", derive(RustcDecodable, RustcEncodable))]
#[cfg_attr(feature = "serde", derive(Deserialize, Serialize))]
pub struct Backtrace {
    // Frames here are listed from top-to-bottom of the stack
    frames: Vec<BacktraceFrame>,
}

fn _assert_send_sync() {
    fn _assert<T: Send + Sync>() {}
    _assert::<Backtrace>();
}

/// 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.
///
/// # Required features
///
/// This function requires the `std` feature of the `backtrace` crate to be
/// enabled, and the `std` feature is enabled by default.
#[derive(Clone)]
pub struct BacktraceFrame {
    frame: Frame,
    symbols: Option<Vec<BacktraceSymbol>>,
}

#[derive(Clone)]
enum Frame {
    Raw(crate::Frame),
    #[allow(dead_code)]
    Deserialized {
        ip: usize,
        symbol_address: usize,
        module_base_address: Option<usize>,
    },
}

impl Frame {
    fn ip(&self) -> *mut c_void {
        match *self {
            Frame::Raw(ref f) => f.ip(),
            Frame::Deserialized { ip, .. } => ip as *mut c_void,
        }
    }

    fn symbol_address(&self) -> *mut c_void {
        match *self {
            Frame::Raw(ref f) => f.symbol_address(),
            Frame::Deserialized { symbol_address, .. } => symbol_address as *mut c_void,
        }
    }

    fn module_base_address(&self) -> Option<*mut c_void> {
        match *self {
            Frame::Raw(ref f) => f.module_base_address(),
            Frame::Deserialized {
                module_base_address,
                ..
            } => module_base_address.map(|addr| addr as *mut c_void),
        }
    }

    /// Resolve all addresses in the frame to their symbolic names.
    fn resolve_symbols(&self) -> Vec<BacktraceSymbol> {
        let mut symbols = Vec::new();
        let sym = |symbol: &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(),
                colno: symbol.colno(),
            });
        };
        match *self {
            Frame::Raw(ref f) => resolve_frame(f, sym),
            Frame::Deserialized { ip, .. } => {
                resolve(ip as *mut c_void, sym);
            }
        }
        symbols
    }
}

/// 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.
///
/// # Required features
///
/// This function requires the `std` feature of the `backtrace` crate to be
/// enabled, and the `std` feature is enabled by default.
#[derive(Clone)]
#[cfg_attr(feature = "serialize-rustc", derive(RustcDecodable, RustcEncodable))]
#[cfg_attr(feature = "serde", derive(Deserialize, Serialize))]
pub struct BacktraceSymbol {
    name: Option<Vec<u8>>,
    addr: Option<usize>,
    filename: Option<PathBuf>,
    lineno: Option<u32>,
    colno: 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.
    ///
    /// Note that on some platforms acquiring a full backtrace and resolving it
    /// can be extremely expensive. If the cost is too much for your application
    /// it's recommended to instead use `Backtrace::new_unresolved()` which
    /// avoids the symbol resolution step (which typically takes the longest)
    /// and allows deferring that to a later date.
    ///
    /// # Examples
    ///
    /// ```
    /// use backtrace::Backtrace;
    ///
    /// let current_backtrace = Backtrace::new();
    /// ```
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    #[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
    /// ```
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    #[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 mut frames = Vec::new();
        trace(|frame| {
            frames.push(BacktraceFrame {
                frame: Frame::Raw(frame.clone()),
                symbols: None,
            });

            // clear inner frames, and start with call site.
            if frame.symbol_address() as usize == ip {
                frames.clear();
            }

            true
        });
        frames.shrink_to_fit();

        Backtrace { frames }
    }

    /// 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.
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn frames(&self) -> &[BacktraceFrame] {
        self.frames.as_slice()
    }

    /// 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.
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn resolve(&mut self) {
        self.frames.iter_mut().for_each(BacktraceFrame::resolve);
    }
}

impl From<Vec<BacktraceFrame>> for Backtrace {
    fn from(frames: Vec<BacktraceFrame>) -> Self {
        Backtrace { frames }
    }
}

impl From<crate::Frame> for BacktraceFrame {
    fn from(frame: crate::Frame) -> Self {
        BacktraceFrame {
            frame: Frame::Raw(frame),
            symbols: None,
        }
    }
}

// we don't want implementing `impl From<Backtrace> for Vec<BacktraceFrame>` on purpose,
// because "... additional directions for Vec<T> can weaken type inference ..."
// more information on https://github.com/rust-lang/backtrace-rs/pull/526
impl Into<Vec<BacktraceFrame>> for Backtrace {
    fn into(self) -> Vec<BacktraceFrame> {
        self.frames
    }
}

impl BacktraceFrame {
    /// Same as `Frame::ip`
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn ip(&self) -> *mut c_void {
        self.frame.ip()
    }

    /// Same as `Frame::symbol_address`
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn symbol_address(&self) -> *mut c_void {
        self.frame.symbol_address()
    }

    /// Same as `Frame::module_base_address`
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn module_base_address(&self) -> Option<*mut c_void> {
        self.frame.module_base_address()
    }

    /// 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.
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn symbols(&self) -> &[BacktraceSymbol] {
        self.symbols.as_ref().map(|s| &s[..]).unwrap_or(&[])
    }

    /// Resolve all addresses in this frame to their symbolic names.
    ///
    /// If this frame has been previously resolved, this function does nothing.
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn resolve(&mut self) {
        if self.symbols.is_none() {
            self.symbols = Some(self.frame.resolve_symbols());
        }
    }
}

impl BacktraceSymbol {
    /// Same as `Symbol::name`
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn name(&self) -> Option<SymbolName<'_>> {
        self.name.as_ref().map(|s| SymbolName::new(s))
    }

    /// Same as `Symbol::addr`
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn addr(&self) -> Option<*mut c_void> {
        self.addr.map(|s| s as *mut c_void)
    }

    /// Same as `Symbol::filename`
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn filename(&self) -> Option<&Path> {
        self.filename.as_ref().map(|p| &**p)
    }

    /// Same as `Symbol::lineno`
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn lineno(&self) -> Option<u32> {
        self.lineno
    }

    /// Same as `Symbol::colno`
    ///
    /// # Required features
    ///
    /// This function requires the `std` feature of the `backtrace` crate to be
    /// enabled, and the `std` feature is enabled by default.
    pub fn colno(&self) -> Option<u32> {
        self.colno
    }
}

impl fmt::Debug for Backtrace {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        let style = if fmt.alternate() {
            PrintFmt::Full
        } else {
            PrintFmt::Short
        };

        // When printing paths we try to strip the cwd if it exists, otherwise
        // we just print the path as-is. Note that we also only do this for the
        // short format, because if it's full we presumably want to print
        // everything.
        let cwd = std::env::current_dir();
        let mut print_path =
            move |fmt: &mut fmt::Formatter<'_>, path: crate::BytesOrWideString<'_>| {
                let path = path.into_path_buf();
                if style == PrintFmt::Full {
                    if let Ok(cwd) = &cwd {
                        if let Ok(suffix) = path.strip_prefix(cwd) {
                            return fmt::Display::fmt(&suffix.display(), fmt);
                        }
                    }
                }
                fmt::Display::fmt(&path.display(), fmt)
            };

        let mut f = BacktraceFmt::new(fmt, style, &mut print_path);
        f.add_context()?;
        for frame in &self.frames {
            f.frame().backtrace_frame(frame)?;
        }
        f.finish()?;
        Ok(())
    }
}

impl Default for Backtrace {
    fn default() -> Backtrace {
        Backtrace::new()
    }
}

impl fmt::Debug for BacktraceFrame {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_struct("BacktraceFrame")
            .field("ip", &self.ip())
            .field("symbol_address", &self.symbol_address())
            .finish()
    }
}

impl fmt::Debug for BacktraceSymbol {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_struct("BacktraceSymbol")
            .field("name", &self.name())
            .field("addr", &self.addr())
            .field("filename", &self.filename())
            .field("lineno", &self.lineno())
            .field("colno", &self.colno())
            .finish()
    }
}

#[cfg(feature = "serialize-rustc")]
mod rustc_serialize_impls {
    use super::*;
    use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};

    #[derive(RustcEncodable, RustcDecodable)]
    struct SerializedFrame {
        ip: usize,
        symbol_address: usize,
        module_base_address: Option<usize>,
        symbols: Option<Vec<BacktraceSymbol>>,
    }

    impl Decodable for BacktraceFrame {
        fn decode<D>(d: &mut D) -> Result<Self, D::Error>
        where
            D: Decoder,
        {
            let frame: SerializedFrame = SerializedFrame::decode(d)?;
            Ok(BacktraceFrame {
                frame: Frame::Deserialized {
                    ip: frame.ip,
                    symbol_address: frame.symbol_address,
                    module_base_address: frame.module_base_address,
                },
                symbols: frame.symbols,
            })
        }
    }

    impl Encodable for BacktraceFrame {
        fn encode<E>(&self, e: &mut E) -> Result<(), E::Error>
        where
            E: Encoder,
        {
            let BacktraceFrame { frame, symbols } = self;
            SerializedFrame {
                ip: frame.ip() as usize,
                symbol_address: frame.symbol_address() as usize,
                module_base_address: frame.module_base_address().map(|addr| addr as usize),
                symbols: symbols.clone(),
            }
            .encode(e)
        }
    }
}

#[cfg(feature = "serde")]
mod serde_impls {
    use super::*;
    use serde::de::Deserializer;
    use serde::ser::Serializer;
    use serde::{Deserialize, Serialize};

    #[derive(Serialize, Deserialize)]
    struct SerializedFrame {
        ip: usize,
        symbol_address: usize,
        module_base_address: Option<usize>,
        symbols: Option<Vec<BacktraceSymbol>>,
    }

    impl Serialize for BacktraceFrame {
        fn serialize<S>(&self, s: S) -> Result<S::Ok, S::Error>
        where
            S: Serializer,
        {
            let BacktraceFrame { frame, symbols } = self;
            SerializedFrame {
                ip: frame.ip() as usize,
                symbol_address: frame.symbol_address() as usize,
                module_base_address: frame.module_base_address().map(|addr| addr as usize),
                symbols: symbols.clone(),
            }
            .serialize(s)
        }
    }

    impl<'a> Deserialize<'a> for BacktraceFrame {
        fn deserialize<D>(d: D) -> Result<Self, D::Error>
        where
            D: Deserializer<'a>,
        {
            let frame: SerializedFrame = SerializedFrame::deserialize(d)?;
            Ok(BacktraceFrame {
                frame: Frame::Deserialized {
                    ip: frame.ip,
                    symbol_address: frame.symbol_address,
                    module_base_address: frame.module_base_address,
                },
                symbols: frame.symbols,
            })
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_frame_conversion() {
        let mut frames = vec![];
        crate::trace(|frame| {
            let converted = BacktraceFrame::from(frame.clone());
            frames.push(converted);
            true
        });

        let mut manual = Backtrace::from(frames);
        manual.resolve();
        let frames = manual.frames();

        for frame in frames {
            println!("{:?}", frame.ip());
            println!("{:?}", frame.symbol_address());
            println!("{:?}", frame.module_base_address());
            println!("{:?}", frame.symbols());
        }
    }
}