1 files changed, 302 insertions, 0 deletions
diff --git a/library/backtrace/src/print.rs b/library/backtrace/src/print.rs
new file mode 100644
index 000000000..cc677122a
--- /dev/null
+++ b/library/backtrace/src/print.rs
@@ -0,0 +1,302 @@
+#[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;
+    }
+}