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
use std::fmt;
#[cfg(not(feature = "cpp_demangle"))]
use std::marker::PhantomData;
use std::os::raw::c_void;
use std::path::Path;
use std::str;
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).
///
/// # Example
///
/// ```
/// extern crate backtrace;
///
/// fn main() {
///     backtrace::trace(|frame| {
///         let ip = frame.ip();
///
///         backtrace::resolve(ip, |symbol| {
///             // ...
///         });
///
///         false // only look at the top frame
///     });
/// }
/// ```
pub fn resolve<F: FnMut(&Symbol)>(addr: *mut c_void, mut cb: F) {
    resolve_imp(addr, &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 {
    inner: SymbolImp,
}

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()
    }

    /// Returns the file name where this function was defined.
    ///
    /// This is currently only available when libbacktrace is being used (e.g.
    /// unix platforms other than OSX) and when a binary is compiled with
    /// debuginfo. If neither of these conditions is met then this will likely
    /// return `None`.
    pub fn filename(&self) -> Option<&Path> {
        self.inner.filename()
    }

    /// 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()
    }
}

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);
        }
        if let Some(filename) = self.filename() {
            d.field("filename", &filename);
        }
        if let Some(lineno) = self.lineno() {
            d.field("lineno", &lineno);
        }
        d.finish()
    }
}


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 {
        // 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 symbol name as a `str` if the symbols is valid utf-8.
    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
    }
}

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 {
                    String::from_utf8_lossy(self.bytes).fmt(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 {
                    String::from_utf8_lossy(self.bytes).fmt(f)
                }
            }
        }
    }
}

cfg_if! {
    if #[cfg(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)
                    }
                }

                String::from_utf8_lossy(self.bytes).fmt(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 {
                    String::from_utf8_lossy(self.bytes).fmt(f)
                }
            }
        }
    }
}

cfg_if! {
    if #[cfg(all(windows, feature = "dbghelp"))] {
        mod dbghelp;
        use self::dbghelp::resolve as resolve_imp;
        use self::dbghelp::Symbol as SymbolImp;
    } else if #[cfg(all(feature = "gimli-symbolize",
                        unix,
                        target_os = "linux"))] {
        mod gimli;
        use self::gimli::resolve as resolve_imp;
        use self::gimli::Symbol as SymbolImp;
    } else if #[cfg(all(feature = "libbacktrace",
                        unix,
                        not(target_os = "emscripten"),
                        not(target_os = "macos"),
                        not(target_os = "ios")))] {
        mod libbacktrace;
        use self::libbacktrace::resolve as resolve_imp;
        use self::libbacktrace::Symbol as SymbolImp;
    } else if #[cfg(all(feature = "coresymbolication",
                        any(target_os = "macos",
                            target_os = "ios")))] {
        mod coresymbolication;
        use self::coresymbolication::resolve as resolve_imp;
        use self::coresymbolication::Symbol as SymbolImp;
    } else if #[cfg(all(unix,
                        not(target_os = "emscripten"),
                        feature = "dladdr"))] {
        mod dladdr;
        use self::dladdr::resolve as resolve_imp;
        use self::dladdr::Symbol as SymbolImp;
    } else {
        mod noop;
        use self::noop::resolve as resolve_imp;
        use self::noop::Symbol as SymbolImp;
    }
}