/rust/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.56/src/print.rs

Source (jump to first uncovered line)
#[cfg(feature = "std")]
use super::{BacktraceFrame, BacktraceSymbol};
use super::{BytesOrWideString, Frame, SymbolName};
use core::ffi::c_void;
use core::fmt;

const HEX_WIDTH: usize = 2 + 2 * core::mem::size_of::<usize>();

#[cfg(target_os = "fuchsia")]
mod fuchsia;

/// A formatter for backtraces.
///
/// This type can be used to print a backtrace regardless of where the backtrace
/// itself comes from. If you have a `Backtrace` type then its `Debug`
/// implementation already uses this printing format.
pub struct BacktraceFmt<'a, 'b> {
    fmt: &'a mut fmt::Formatter<'b>,
    frame_index: usize,
    format: PrintFmt,
    print_path:
        &'a mut (dyn FnMut(&mut fmt::Formatter<'_>, BytesOrWideString<'_>) -> fmt::Result + 'b),
}

/// The styles of printing that we can print
#[derive(Copy, Clone, Eq, PartialEq)]
pub enum PrintFmt {
    /// Prints a terser backtrace which ideally only contains relevant information
    Short,
    /// Prints a backtrace that contains all possible information
    Full,
    #[doc(hidden)]
    __Nonexhaustive,
}

impl<'a, 'b> BacktraceFmt<'a, 'b> {
    /// Create a new `BacktraceFmt` which will write output to the provided
    /// `fmt`.
    ///
    /// The `format` argument will control the style in which the backtrace is
    /// printed, and the `print_path` argument will be used to print the
    /// `BytesOrWideString` instances of filenames. This type itself doesn't do
    /// any printing of filenames, but this callback is required to do so.
    pub fn new(
        fmt: &'a mut fmt::Formatter<'b>,
        format: PrintFmt,
        print_path: &'a mut (dyn FnMut(&mut fmt::Formatter<'_>, BytesOrWideString<'_>) -> fmt::Result
                     + 'b),
    ) -> Self {
        BacktraceFmt {
            fmt,
            frame_index: 0,
            format,
            print_path,
        }
    }

    /// Prints a preamble for the backtrace about to be printed.
    ///
    /// This is required on some platforms for backtraces to be fully
    /// symbolicated later, and otherwise this should just be the first method
    /// you call after creating a `BacktraceFmt`.
    pub fn add_context(&mut self) -> fmt::Result {
        #[cfg(target_os = "fuchsia")]
        fuchsia::print_dso_context(self.fmt)?;
        Ok(())
    }

    /// Adds a frame to the backtrace output.
    ///
    /// This commit returns an RAII instance of a `BacktraceFrameFmt` which can be used
    /// to actually print a frame, and on destruction it will increment the
    /// frame counter.
    pub fn frame(&mut self) -> BacktraceFrameFmt<'_, 'a, 'b> {
        BacktraceFrameFmt {
            fmt: self,
            symbol_index: 0,
        }
    }

    /// Completes the backtrace output.
    ///
    /// This is currently a no-op but is added for future compatibility with
    /// backtrace formats.
    pub fn finish(&mut self) -> fmt::Result {
        // Currently a no-op-- including this hook to allow for future additions.
        Ok(())
    }
}

/// A formatter for just one frame of a backtrace.
///
/// This type is created by the `BacktraceFmt::frame` function.
pub struct BacktraceFrameFmt<'fmt, 'a, 'b> {
    fmt: &'fmt mut BacktraceFmt<'a, 'b>,
    symbol_index: usize,
}

impl BacktraceFrameFmt<'_, '_, '_> {
    /// Prints a `BacktraceFrame` with this frame formatter.
    ///
    /// This will recursively print all `BacktraceSymbol` instances within the
    /// `BacktraceFrame`.
    ///
    /// # 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")]
    pub fn backtrace_frame(&mut self, frame: &BacktraceFrame) -> fmt::Result {
        let symbols = frame.symbols();
        for symbol in symbols {
            self.backtrace_symbol(frame, symbol)?;
        }
        if symbols.is_empty() {
            self.print_raw(frame.ip(), None, None, None)?;
        }
        Ok(())
    }

    /// Prints a `BacktraceSymbol` within a `BacktraceFrame`.
    ///
    /// # 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")]
    pub fn backtrace_symbol(
        &mut self,
        frame: &BacktraceFrame,
        symbol: &BacktraceSymbol,
    ) -> fmt::Result {
        self.print_raw_with_column(
            frame.ip(),
            symbol.name(),
            // TODO: this isn't great that we don't end up printing anything
            // with non-utf8 filenames. Thankfully almost everything is utf8 so
            // this shouldn't be too too bad.
            symbol
                .filename()
                .and_then(|p| Some(BytesOrWideString::Bytes(p.to_str()?.as_bytes()))),
            symbol.lineno(),
            symbol.colno(),
        )?;
        Ok(())
    }

    /// Prints a raw traced `Frame` and `Symbol`, typically from within the raw
    /// callbacks of this crate.
    pub fn symbol(&mut self, frame: &Frame, symbol: &super::Symbol) -> fmt::Result {
        self.print_raw_with_column(
            frame.ip(),
            symbol.name(),
            symbol.filename_raw(),
            symbol.lineno(),
            symbol.colno(),
        )?;
        Ok(())
    }

    /// Adds a raw frame to the backtrace output.
    ///
    /// This method, unlike the previous, takes the raw arguments in case
    /// they're being source from different locations. Note that this may be
    /// called multiple times for one frame.
    pub fn print_raw(
        &mut self,
        frame_ip: *mut c_void,
        symbol_name: Option<SymbolName<'_>>,
        filename: Option<BytesOrWideString<'_>>,
        lineno: Option<u32>,
    ) -> fmt::Result {
        self.print_raw_with_column(frame_ip, symbol_name, filename, lineno, None)
    }

    /// Adds a raw frame to the backtrace output, including column information.
    ///
    /// This method, like the previous, takes the raw arguments in case
    /// they're being source from different locations. Note that this may be
    /// called multiple times for one frame.
    pub fn print_raw_with_column(
        &mut self,
        frame_ip: *mut c_void,
        symbol_name: Option<SymbolName<'_>>,
        filename: Option<BytesOrWideString<'_>>,
        lineno: Option<u32>,
        colno: Option<u32>,
    ) -> fmt::Result {
        // Fuchsia is unable to symbolize within a process so it has a special
        // format which can be used to symbolize later. Print that instead of
        // printing addresses in our own format here.
        if cfg!(target_os = "fuchsia") {
            self.print_raw_fuchsia(frame_ip)?;
        } else {
            self.print_raw_generic(frame_ip, symbol_name, filename, lineno, colno)?;
        }
        self.symbol_index += 1;
        Ok(())
    }

    #[allow(unused_mut)]
    fn print_raw_generic(
        &mut self,
        mut frame_ip: *mut c_void,
        symbol_name: Option<SymbolName<'_>>,
        filename: Option<BytesOrWideString<'_>>,
        lineno: Option<u32>,
        colno: Option<u32>,
    ) -> fmt::Result {
        // No need to print "null" frames, it basically just means that the
        // system backtrace was a bit eager to trace back super far.
        if let PrintFmt::Short = self.fmt.format {
            if frame_ip.is_null() {
                return Ok(());
            }
        }

        // To reduce TCB size in Sgx enclave, we do not want to implement symbol
        // resolution functionality.  Rather, we can print the offset of the
        // address here, which could be later mapped to correct function.
        #[cfg(all(feature = "std", target_env = "sgx", target_vendor = "fortanix"))]
        {
            let image_base = std::os::fortanix_sgx::mem::image_base();
            frame_ip = usize::wrapping_sub(frame_ip as usize, image_base as _) as _;
        }

        // Print the index of the frame as well as the optional instruction
        // pointer of the frame. If we're beyond the first symbol of this frame
        // though we just print appropriate whitespace.
        if self.symbol_index == 0 {
            write!(self.fmt.fmt, "{:4}: ", self.fmt.frame_index)?;
            if let PrintFmt::Full = self.fmt.format {
                write!(self.fmt.fmt, "{:1$?} - ", frame_ip, HEX_WIDTH)?;
            }
        } else {
            write!(self.fmt.fmt, "      ")?;
            if let PrintFmt::Full = self.fmt.format {
                write!(self.fmt.fmt, "{:1$}", "", HEX_WIDTH + 3)?;
            }
        }

        // Next up write out the symbol name, using the alternate formatting for
        // more information if we're a full backtrace. Here we also handle
        // symbols which don't have a name,
        match (symbol_name, &self.fmt.format) {
            (Some(name), PrintFmt::Short) => write!(self.fmt.fmt, "{:#}", name)?,
            (Some(name), PrintFmt::Full) => write!(self.fmt.fmt, "{}", name)?,
            (None, _) | (_, PrintFmt::__Nonexhaustive) => write!(self.fmt.fmt, "<unknown>")?,
        }
        self.fmt.fmt.write_str("\n")?;

        // And last up, print out the filename/line number if they're available.
        if let (Some(file), Some(line)) = (filename, lineno) {
            self.print_fileline(file, line, colno)?;
        }

        Ok(())
    }

    fn print_fileline(
        &mut self,
        file: BytesOrWideString<'_>,
        line: u32,
        colno: Option<u32>,
    ) -> fmt::Result {
        // Filename/line are printed on lines under the symbol name, so print
        // some appropriate whitespace to sort of right-align ourselves.
        if let PrintFmt::Full = self.fmt.format {
            write!(self.fmt.fmt, "{:1$}", "", HEX_WIDTH)?;
        }
        write!(self.fmt.fmt, "             at ")?;

        // Delegate to our internal callback to print the filename and then
        // print out the line number.
        (self.fmt.print_path)(self.fmt.fmt, file)?;
        write!(self.fmt.fmt, ":{}", line)?;

        // Add column number, if available.
        if let Some(colno) = colno {
            write!(self.fmt.fmt, ":{}", colno)?;
        }

        write!(self.fmt.fmt, "\n")?;
        Ok(())
    }

    fn print_raw_fuchsia(&mut self, frame_ip: *mut c_void) -> fmt::Result {
        // We only care about the first symbol of a frame
        if self.symbol_index == 0 {
            self.fmt.fmt.write_str("{{{bt:")?;
            write!(self.fmt.fmt, "{}:{:?}", self.fmt.frame_index, frame_ip)?;
            self.fmt.fmt.write_str("}}}\n")?;
        }
        Ok(())
    }
}

impl Drop for BacktraceFrameFmt<'_, '_, '_> {
    fn drop(&mut self) {
        self.fmt.frame_index += 1;
    }
}

Coverage Report

Created: 2021-03-22 08:29

Line	Count	Source (jump to first uncovered line)
1		#[cfg(feature = "std")]
2		use super::{BacktraceFrame, BacktraceSymbol};
3		use super::{BytesOrWideString, Frame, SymbolName};
4		use core::ffi::c_void;
5		use core::fmt;
6
7		const HEX_WIDTH: usize = 2 + 2 * core::mem::size_of::<usize>();
8
9		#[cfg(target_os = "fuchsia")]
10		mod fuchsia;
11
12		/// A formatter for backtraces.
13		///
14		/// This type can be used to print a backtrace regardless of where the backtrace
15		/// itself comes from. If you have a `Backtrace` type then its `Debug`
16		/// implementation already uses this printing format.
17		pub struct BacktraceFmt<'a, 'b> {
18		fmt: &'a mut fmt::Formatter<'b>,
19		frame_index: usize,
20		format: PrintFmt,
21		print_path:
22		&'a mut (dyn FnMut(&mut fmt::Formatter<'_>, BytesOrWideString<'_>) -> fmt::Result + 'b),
23		}
24
25		/// The styles of printing that we can print
26		#[derive(Copy, Clone, Eq, PartialEq)]
27		pub enum PrintFmt {
28		/// Prints a terser backtrace which ideally only contains relevant information
29		Short,
30		/// Prints a backtrace that contains all possible information
31		Full,
32		#[doc(hidden)]
33		__Nonexhaustive,
34		}
35
36		impl<'a, 'b> BacktraceFmt<'a, 'b> {
37		/// Create a new `BacktraceFmt` which will write output to the provided
38		/// `fmt`.
39		///
40		/// The `format` argument will control the style in which the backtrace is
41		/// printed, and the `print_path` argument will be used to print the
42		/// `BytesOrWideString` instances of filenames. This type itself doesn't do
43		/// any printing of filenames, but this callback is required to do so.
44		pub fn new(
45		fmt: &'a mut fmt::Formatter<'b>,
46		format: PrintFmt,
47		print_path: &'a mut (dyn FnMut(&mut fmt::Formatter<'_>, BytesOrWideString<'_>) -> fmt::Result
48		+ 'b),
49		) -> Self {
50		BacktraceFmt {
51		fmt,
52		frame_index: 0,
53		format,
54		print_path,
55		}
56		}
57
58		/// Prints a preamble for the backtrace about to be printed.
59		///
60		/// This is required on some platforms for backtraces to be fully
61		/// symbolicated later, and otherwise this should just be the first method
62		/// you call after creating a `BacktraceFmt`.
63		pub fn add_context(&mut self) -> fmt::Result {
64		#[cfg(target_os = "fuchsia")]
65		fuchsia::print_dso_context(self.fmt)?;
66		Ok(())
67		}
68
69		/// Adds a frame to the backtrace output.
70		///
71		/// This commit returns an RAII instance of a `BacktraceFrameFmt` which can be used
72		/// to actually print a frame, and on destruction it will increment the
73		/// frame counter.
74		pub fn frame(&mut self) -> BacktraceFrameFmt<'_, 'a, 'b> {
75		BacktraceFrameFmt {
76		fmt: self,
77		symbol_index: 0,
78		}
79		}
80
81		/// Completes the backtrace output.
82		///
83		/// This is currently a no-op but is added for future compatibility with
84		/// backtrace formats.
85		pub fn finish(&mut self) -> fmt::Result {
86		// Currently a no-op-- including this hook to allow for future additions.
87		Ok(())
88		}
89		}
90
91		/// A formatter for just one frame of a backtrace.
92		///
93		/// This type is created by the `BacktraceFmt::frame` function.
94		pub struct BacktraceFrameFmt<'fmt, 'a, 'b> {
95		fmt: &'fmt mut BacktraceFmt<'a, 'b>,
96		symbol_index: usize,
97		}
98
99		impl BacktraceFrameFmt<'_, '_, '_> {
100		/// Prints a `BacktraceFrame` with this frame formatter.
101		///
102		/// This will recursively print all `BacktraceSymbol` instances within the
103		/// `BacktraceFrame`.
104		///
105		/// # Required features
106		///
107		/// This function requires the `std` feature of the `backtrace` crate to be
108		/// enabled, and the `std` feature is enabled by default.
109		#[cfg(feature = "std")]
110	0	pub fn backtrace_frame(&mut self, frame: &BacktraceFrame) -> fmt::Result {
111	0	let symbols = frame.symbols();
112	0	for symbol in symbols {
113	0	self.backtrace_symbol(frame, symbol)?;
114		}
115	0	if symbols.is_empty() {
116	0	self.print_raw(frame.ip(), None, None, None)?;
117	0	}
118	0	Ok(())
119	0	}
120
121		/// Prints a `BacktraceSymbol` within a `BacktraceFrame`.
122		///
123		/// # Required features
124		///
125		/// This function requires the `std` feature of the `backtrace` crate to be
126		/// enabled, and the `std` feature is enabled by default.
127		#[cfg(feature = "std")]
128		pub fn backtrace_symbol(
129		&mut self,
130		frame: &BacktraceFrame,
131		symbol: &BacktraceSymbol,
132		) -> fmt::Result {
133	0	self.print_raw_with_column(
134	0	frame.ip(),
135	0	symbol.name(),
136	0	// TODO: this isn't great that we don't end up printing anything
137	0	// with non-utf8 filenames. Thankfully almost everything is utf8 so
138	0	// this shouldn't be too too bad.
139	0	symbol
140	0	.filename()
141	0	.and_then(\|p\| Some(BytesOrWideString::Bytes(p.to_str()?.as_bytes()))),
142	0	symbol.lineno(),
143	0	symbol.colno(),
144	0	)?;
145	0	Ok(())
146	0	}
147
148		/// Prints a raw traced `Frame` and `Symbol`, typically from within the raw
149		/// callbacks of this crate.
150		pub fn symbol(&mut self, frame: &Frame, symbol: &super::Symbol) -> fmt::Result {
151	0	self.print_raw_with_column(
152	0	frame.ip(),
153	0	symbol.name(),
154	0	symbol.filename_raw(),
155	0	symbol.lineno(),
156	0	symbol.colno(),
157	0	)?;
158	0	Ok(())
159	0	}
160
161		/// Adds a raw frame to the backtrace output.
162		///
163		/// This method, unlike the previous, takes the raw arguments in case
164		/// they're being source from different locations. Note that this may be
165		/// called multiple times for one frame.
166		pub fn print_raw(
167		&mut self,
168		frame_ip: *mut c_void,
169		symbol_name: Option<SymbolName<'_>>,
170		filename: Option<BytesOrWideString<'_>>,
171		lineno: Option<u32>,
172		) -> fmt::Result {
173		self.print_raw_with_column(frame_ip, symbol_name, filename, lineno, None)
174		}
175
176		/// Adds a raw frame to the backtrace output, including column information.
177		///
178		/// This method, like the previous, takes the raw arguments in case
179		/// they're being source from different locations. Note that this may be
180		/// called multiple times for one frame.
181		pub fn print_raw_with_column(
182		&mut self,
183		frame_ip: *mut c_void,
184		symbol_name: Option<SymbolName<'_>>,
185		filename: Option<BytesOrWideString<'_>>,
186		lineno: Option<u32>,
187		colno: Option<u32>,
188		) -> fmt::Result {
189		// Fuchsia is unable to symbolize within a process so it has a special
190		// format which can be used to symbolize later. Print that instead of
191		// printing addresses in our own format here.
192		if cfg!(target_os = "fuchsia") {
193		self.print_raw_fuchsia(frame_ip)?;
194		} else {
195		self.print_raw_generic(frame_ip, symbol_name, filename, lineno, colno)?;
196		}
197		self.symbol_index += 1;
198		Ok(())
199		}
200
201		#[allow(unused_mut)]
202	0	fn print_raw_generic(
203	0	&mut self,
204	0	mut frame_ip: *mut c_void,
205	0	symbol_name: Option<SymbolName<'_>>,
206	0	filename: Option<BytesOrWideString<'_>>,
207	0	lineno: Option<u32>,
208	0	colno: Option<u32>,
209	0	) -> fmt::Result {
210	0	// No need to print "null" frames, it basically just means that the
211	0	// system backtrace was a bit eager to trace back super far.
212	0	if let PrintFmt::Short = self.fmt.format {
213	0	if frame_ip.is_null() {
214	0	return Ok(());
215	0	}
216	0	}
217
218		// To reduce TCB size in Sgx enclave, we do not want to implement symbol
219		// resolution functionality. Rather, we can print the offset of the
220		// address here, which could be later mapped to correct function.
221		#[cfg(all(feature = "std", target_env = "sgx", target_vendor = "fortanix"))]
222		{
223		let image_base = std::os::fortanix_sgx::mem::image_base();
224		frame_ip = usize::wrapping_sub(frame_ip as usize, image_base as _) as _;
225		}
226
227		// Print the index of the frame as well as the optional instruction
228		// pointer of the frame. If we're beyond the first symbol of this frame
229		// though we just print appropriate whitespace.
230	0	if self.symbol_index == 0 {
231	0	write!(self.fmt.fmt, "{:4}: ", self.fmt.frame_index)?;
232	0	if let PrintFmt::Full = self.fmt.format {
233	0	write!(self.fmt.fmt, "{:1$?} - ", frame_ip, HEX_WIDTH)?;
234	0	}
235		} else {
236	0	write!(self.fmt.fmt, " ")?;
237	0	if let PrintFmt::Full = self.fmt.format {
238	0	write!(self.fmt.fmt, "{:1$}", "", HEX_WIDTH + 3)?;
239	0	}
240		}
241
242		// Next up write out the symbol name, using the alternate formatting for
243		// more information if we're a full backtrace. Here we also handle
244		// symbols which don't have a name,
245	0	match (symbol_name, &self.fmt.format) {
246	0	(Some(name), PrintFmt::Short) => write!(self.fmt.fmt, "{:#}", name)?,
247	0	(Some(name), PrintFmt::Full) => write!(self.fmt.fmt, "{}", name)?,
248	0	(None, _) \| (_, PrintFmt::__Nonexhaustive) => write!(self.fmt.fmt, "<unknown>")?,
249		}
250	0	self.fmt.fmt.write_str("\n")?;
251
252		// And last up, print out the filename/line number if they're available.
253	0	if let (Some(file), Some(line)) = (filename, lineno) {
254	0	self.print_fileline(file, line, colno)?;
255	0	}
256
257	0	Ok(())
258	0	}
259
260	0	fn print_fileline(
261	0	&mut self,
262	0	file: BytesOrWideString<'_>,
263	0	line: u32,
264	0	colno: Option<u32>,
265	0	) -> fmt::Result {
266	0	// Filename/line are printed on lines under the symbol name, so print
267	0	// some appropriate whitespace to sort of right-align ourselves.
268	0	if let PrintFmt::Full = self.fmt.format {
269	0	write!(self.fmt.fmt, "{:1$}", "", HEX_WIDTH)?;
270	0	}
271	0	write!(self.fmt.fmt, " at ")?;
272
273		// Delegate to our internal callback to print the filename and then
274		// print out the line number.
275	0	(self.fmt.print_path)(self.fmt.fmt, file)?;
276	0	write!(self.fmt.fmt, ":{}", line)?;
277
278		// Add column number, if available.
279	0	if let Some(colno) = colno {
280	0	write!(self.fmt.fmt, ":{}", colno)?;
281	0	}
282
283	0	write!(self.fmt.fmt, "\n")?;
284	0	Ok(())
285	0	}
286
287		fn print_raw_fuchsia(&mut self, frame_ip: *mut c_void) -> fmt::Result {
288		// We only care about the first symbol of a frame
289		if self.symbol_index == 0 {
290		self.fmt.fmt.write_str("{{{bt:")?;
291		write!(self.fmt.fmt, "{}:{:?}", self.fmt.frame_index, frame_ip)?;
292		self.fmt.fmt.write_str("}}}\n")?;
293		}
294		Ok(())
295		}
296		}
297
298		impl Drop for BacktraceFrameFmt<'_, '_, '_> {
299		fn drop(&mut self) {
300		self.fmt.frame_index += 1;
301		}
302		}