diff options
Diffstat (limited to 'library/backtrace/src/backtrace')
| -rw-r--r-- | library/backtrace/src/backtrace/dbghelp.rs | 257 | ||||
| -rw-r--r-- | library/backtrace/src/backtrace/libunwind.rs | 267 | ||||
| -rw-r--r-- | library/backtrace/src/backtrace/miri.rs | 107 | ||||
| -rw-r--r-- | library/backtrace/src/backtrace/mod.rs | 162 | ||||
| -rw-r--r-- | library/backtrace/src/backtrace/noop.rs | 28 |
5 files changed, 821 insertions, 0 deletions
diff --git a/library/backtrace/src/backtrace/dbghelp.rs b/library/backtrace/src/backtrace/dbghelp.rs new file mode 100644 index 000000000..ba0f05f3b --- /dev/null +++ b/library/backtrace/src/backtrace/dbghelp.rs @@ -0,0 +1,257 @@ +//! Backtrace strategy for MSVC platforms. +//! +//! This module contains the ability to generate a backtrace on MSVC using one +//! of two possible methods. The `StackWalkEx` function is primarily used if +//! possible, but not all systems have that. Failing that the `StackWalk64` +//! function is used instead. Note that `StackWalkEx` is favored because it +//! handles debuginfo internally and returns inline frame information. +//! +//! Note that all dbghelp support is loaded dynamically, see `src/dbghelp.rs` +//! for more information about that. + +#![allow(bad_style)] + +use super::super::{dbghelp, windows::*}; +use core::ffi::c_void; +use core::mem; + +#[derive(Clone, Copy)] +pub enum StackFrame { + New(STACKFRAME_EX), + Old(STACKFRAME64), +} + +#[derive(Clone, Copy)] +pub struct Frame { + pub(crate) stack_frame: StackFrame, + base_address: *mut c_void, +} + +// we're just sending around raw pointers and reading them, never interpreting +// them so this should be safe to both send and share across threads. +unsafe impl Send for Frame {} +unsafe impl Sync for Frame {} + +impl Frame { + pub fn ip(&self) -> *mut c_void { + self.addr_pc().Offset as *mut _ + } + + pub fn sp(&self) -> *mut c_void { + self.addr_stack().Offset as *mut _ + } + + pub fn symbol_address(&self) -> *mut c_void { + self.ip() + } + + pub fn module_base_address(&self) -> Option<*mut c_void> { + Some(self.base_address) + } + + fn addr_pc(&self) -> &ADDRESS64 { + match self.stack_frame { + StackFrame::New(ref new) => &new.AddrPC, + StackFrame::Old(ref old) => &old.AddrPC, + } + } + + fn addr_pc_mut(&mut self) -> &mut ADDRESS64 { + match self.stack_frame { + StackFrame::New(ref mut new) => &mut new.AddrPC, + StackFrame::Old(ref mut old) => &mut old.AddrPC, + } + } + + fn addr_frame_mut(&mut self) -> &mut ADDRESS64 { + match self.stack_frame { + StackFrame::New(ref mut new) => &mut new.AddrFrame, + StackFrame::Old(ref mut old) => &mut old.AddrFrame, + } + } + + fn addr_stack(&self) -> &ADDRESS64 { + match self.stack_frame { + StackFrame::New(ref new) => &new.AddrStack, + StackFrame::Old(ref old) => &old.AddrStack, + } + } + + fn addr_stack_mut(&mut self) -> &mut ADDRESS64 { + match self.stack_frame { + StackFrame::New(ref mut new) => &mut new.AddrStack, + StackFrame::Old(ref mut old) => &mut old.AddrStack, + } + } +} + +#[repr(C, align(16))] // required by `CONTEXT`, is a FIXME in winapi right now +struct MyContext(CONTEXT); + +#[inline(always)] +pub unsafe fn trace(cb: &mut dyn FnMut(&super::Frame) -> bool) { + // Allocate necessary structures for doing the stack walk + let process = GetCurrentProcess(); + let thread = GetCurrentThread(); + + let mut context = mem::zeroed::<MyContext>(); + RtlCaptureContext(&mut context.0); + + // Ensure this process's symbols are initialized + let dbghelp = match dbghelp::init() { + Ok(dbghelp) => dbghelp, + Err(()) => return, // oh well... + }; + + // On x86_64 and ARM64 we opt to not use the default `Sym*` functions from + // dbghelp for getting the function table and module base. Instead we use + // the `RtlLookupFunctionEntry` function in kernel32 which will account for + // JIT compiler frames as well. These should be equivalent, but using + // `Rtl*` allows us to backtrace through JIT frames. + // + // Note that `RtlLookupFunctionEntry` only works for in-process backtraces, + // but that's all we support anyway, so it all lines up well. + cfg_if::cfg_if! { + if #[cfg(target_pointer_width = "64")] { + use core::ptr; + + unsafe extern "system" fn function_table_access(_process: HANDLE, addr: DWORD64) -> PVOID { + let mut base = 0; + RtlLookupFunctionEntry(addr, &mut base, ptr::null_mut()).cast() + } + + unsafe extern "system" fn get_module_base(_process: HANDLE, addr: DWORD64) -> DWORD64 { + let mut base = 0; + RtlLookupFunctionEntry(addr, &mut base, ptr::null_mut()); + base + } + } else { + let function_table_access = dbghelp.SymFunctionTableAccess64(); + let get_module_base = dbghelp.SymGetModuleBase64(); + } + } + + let process_handle = GetCurrentProcess(); + + // Attempt to use `StackWalkEx` if we can, but fall back to `StackWalk64` + // since it's in theory supported on more systems. + match (*dbghelp.dbghelp()).StackWalkEx() { + Some(StackWalkEx) => { + let mut inner: STACKFRAME_EX = mem::zeroed(); + inner.StackFrameSize = mem::size_of::<STACKFRAME_EX>() as DWORD; + let mut frame = super::Frame { + inner: Frame { + stack_frame: StackFrame::New(inner), + base_address: 0 as _, + }, + }; + let image = init_frame(&mut frame.inner, &context.0); + let frame_ptr = match &mut frame.inner.stack_frame { + StackFrame::New(ptr) => ptr as *mut STACKFRAME_EX, + _ => unreachable!(), + }; + + while StackWalkEx( + image as DWORD, + process, + thread, + frame_ptr, + &mut context.0 as *mut CONTEXT as *mut _, + None, + Some(function_table_access), + Some(get_module_base), + None, + 0, + ) == TRUE + { + frame.inner.base_address = get_module_base(process_handle, frame.ip() as _) as _; + + if !cb(&frame) { + break; + } + } + } + None => { + let mut frame = super::Frame { + inner: Frame { + stack_frame: StackFrame::Old(mem::zeroed()), + base_address: 0 as _, + }, + }; + let image = init_frame(&mut frame.inner, &context.0); + let frame_ptr = match &mut frame.inner.stack_frame { + StackFrame::Old(ptr) => ptr as *mut STACKFRAME64, + _ => unreachable!(), + }; + + while dbghelp.StackWalk64()( + image as DWORD, + process, + thread, + frame_ptr, + &mut context.0 as *mut CONTEXT as *mut _, + None, + Some(function_table_access), + Some(get_module_base), + None, + ) == TRUE + { + frame.inner.base_address = get_module_base(process_handle, frame.ip() as _) as _; + + if !cb(&frame) { + break; + } + } + } + } +} + +#[cfg(target_arch = "x86_64")] +fn init_frame(frame: &mut Frame, ctx: &CONTEXT) -> WORD { + frame.addr_pc_mut().Offset = ctx.Rip as u64; + frame.addr_pc_mut().Mode = AddrModeFlat; + frame.addr_stack_mut().Offset = ctx.Rsp as u64; + frame.addr_stack_mut().Mode = AddrModeFlat; + frame.addr_frame_mut().Offset = ctx.Rbp as u64; + frame.addr_frame_mut().Mode = AddrModeFlat; + + IMAGE_FILE_MACHINE_AMD64 +} + +#[cfg(target_arch = "x86")] +fn init_frame(frame: &mut Frame, ctx: &CONTEXT) -> WORD { + frame.addr_pc_mut().Offset = ctx.Eip as u64; + frame.addr_pc_mut().Mode = AddrModeFlat; + frame.addr_stack_mut().Offset = ctx.Esp as u64; + frame.addr_stack_mut().Mode = AddrModeFlat; + frame.addr_frame_mut().Offset = ctx.Ebp as u64; + frame.addr_frame_mut().Mode = AddrModeFlat; + + IMAGE_FILE_MACHINE_I386 +} + +#[cfg(target_arch = "aarch64")] +fn init_frame(frame: &mut Frame, ctx: &CONTEXT) -> WORD { + frame.addr_pc_mut().Offset = ctx.Pc as u64; + frame.addr_pc_mut().Mode = AddrModeFlat; + frame.addr_stack_mut().Offset = ctx.Sp as u64; + frame.addr_stack_mut().Mode = AddrModeFlat; + unsafe { + frame.addr_frame_mut().Offset = ctx.u.s().Fp as u64; + } + frame.addr_frame_mut().Mode = AddrModeFlat; + IMAGE_FILE_MACHINE_ARM64 +} + +#[cfg(target_arch = "arm")] +fn init_frame(frame: &mut Frame, ctx: &CONTEXT) -> WORD { + frame.addr_pc_mut().Offset = ctx.Pc as u64; + frame.addr_pc_mut().Mode = AddrModeFlat; + frame.addr_stack_mut().Offset = ctx.Sp as u64; + frame.addr_stack_mut().Mode = AddrModeFlat; + unsafe { + frame.addr_frame_mut().Offset = ctx.R11 as u64; + } + frame.addr_frame_mut().Mode = AddrModeFlat; + IMAGE_FILE_MACHINE_ARMNT +} diff --git a/library/backtrace/src/backtrace/libunwind.rs b/library/backtrace/src/backtrace/libunwind.rs new file mode 100644 index 000000000..ef77edda5 --- /dev/null +++ b/library/backtrace/src/backtrace/libunwind.rs @@ -0,0 +1,267 @@ +//! Backtrace support using libunwind/gcc_s/etc APIs. +//! +//! This module contains the ability to unwind the stack using libunwind-style +//! APIs. Note that there's a whole bunch of implementations of the +//! libunwind-like API, and this is just trying to be compatible with most of +//! them all at once instead of being picky. +//! +//! The libunwind API is powered by `_Unwind_Backtrace` and is in practice very +//! reliable at generating a backtrace. It's not entirely clear how it does it +//! (frame pointers? eh_frame info? both?) but it seems to work! +//! +//! Most of the complexity of this module is handling the various platform +//! differences across libunwind implementations. Otherwise this is a pretty +//! straightforward Rust binding to the libunwind APIs. +//! +//! This is the default unwinding API for all non-Windows platforms currently. + +use super::super::Bomb; +use core::ffi::c_void; + +pub enum Frame { + Raw(*mut uw::_Unwind_Context), + Cloned { + ip: *mut c_void, + sp: *mut c_void, + symbol_address: *mut c_void, + }, +} + +// With a raw libunwind pointer it should only ever be access in a readonly +// threadsafe fashion, so it's `Sync`. When sending to other threads via `Clone` +// we always switch to a version which doesn't retain interior pointers, so we +// should be `Send` as well. +unsafe impl Send for Frame {} +unsafe impl Sync for Frame {} + +impl Frame { + pub fn ip(&self) -> *mut c_void { + let ctx = match *self { + Frame::Raw(ctx) => ctx, + Frame::Cloned { ip, .. } => return ip, + }; + unsafe { uw::_Unwind_GetIP(ctx) as *mut c_void } + } + + pub fn sp(&self) -> *mut c_void { + match *self { + Frame::Raw(ctx) => unsafe { uw::get_sp(ctx) as *mut c_void }, + Frame::Cloned { sp, .. } => sp, + } + } + + pub fn symbol_address(&self) -> *mut c_void { + if let Frame::Cloned { symbol_address, .. } = *self { + return symbol_address; + } + + // The macOS linker emits a "compact" unwind table that only includes an + // entry for a function if that function either has an LSDA or its + // encoding differs from that of the previous entry. Consequently, on + // macOS, `_Unwind_FindEnclosingFunction` is unreliable (it can return a + // pointer to some totally unrelated function). Instead, we just always + // return the ip. + // + // https://github.com/rust-lang/rust/issues/74771#issuecomment-664056788 + // + // Note the `skip_inner_frames.rs` test is skipped on macOS due to this + // clause, and if this is fixed that test in theory can be run on macOS! + if cfg!(target_os = "macos") || cfg!(target_os = "ios") { + self.ip() + } else { + unsafe { uw::_Unwind_FindEnclosingFunction(self.ip()) } + } + } + + pub fn module_base_address(&self) -> Option<*mut c_void> { + None + } +} + +impl Clone for Frame { + fn clone(&self) -> Frame { + Frame::Cloned { + ip: self.ip(), + sp: self.sp(), + symbol_address: self.symbol_address(), + } + } +} + +#[inline(always)] +pub unsafe fn trace(mut cb: &mut dyn FnMut(&super::Frame) -> bool) { + uw::_Unwind_Backtrace(trace_fn, &mut cb as *mut _ as *mut _); + + extern "C" fn trace_fn( + ctx: *mut uw::_Unwind_Context, + arg: *mut c_void, + ) -> uw::_Unwind_Reason_Code { + let cb = unsafe { &mut *(arg as *mut &mut dyn FnMut(&super::Frame) -> bool) }; + let cx = super::Frame { + inner: Frame::Raw(ctx), + }; + + let mut bomb = Bomb { enabled: true }; + let keep_going = cb(&cx); + bomb.enabled = false; + + if keep_going { + uw::_URC_NO_REASON + } else { + uw::_URC_FAILURE + } + } +} + +/// Unwind library interface used for backtraces +/// +/// Note that dead code is allowed as here are just bindings +/// iOS doesn't use all of them it but adding more +/// platform-specific configs pollutes the code too much +#[allow(non_camel_case_types)] +#[allow(non_snake_case)] +#[allow(dead_code)] +mod uw { + pub use self::_Unwind_Reason_Code::*; + + use core::ffi::c_void; + + #[repr(C)] + pub enum _Unwind_Reason_Code { + _URC_NO_REASON = 0, + _URC_FOREIGN_EXCEPTION_CAUGHT = 1, + _URC_FATAL_PHASE2_ERROR = 2, + _URC_FATAL_PHASE1_ERROR = 3, + _URC_NORMAL_STOP = 4, + _URC_END_OF_STACK = 5, + _URC_HANDLER_FOUND = 6, + _URC_INSTALL_CONTEXT = 7, + _URC_CONTINUE_UNWIND = 8, + _URC_FAILURE = 9, // used only by ARM EABI + } + + pub enum _Unwind_Context {} + + pub type _Unwind_Trace_Fn = + extern "C" fn(ctx: *mut _Unwind_Context, arg: *mut c_void) -> _Unwind_Reason_Code; + + extern "C" { + pub fn _Unwind_Backtrace( + trace: _Unwind_Trace_Fn, + trace_argument: *mut c_void, + ) -> _Unwind_Reason_Code; + } + + cfg_if::cfg_if! { + // available since GCC 4.2.0, should be fine for our purpose + if #[cfg(all( + not(all(target_os = "android", target_arch = "arm")), + not(all(target_os = "freebsd", target_arch = "arm")), + not(all(target_os = "linux", target_arch = "arm")), + not(all(target_os = "horizon", target_arch = "arm")) + ))] { + extern "C" { + pub fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> libc::uintptr_t; + pub fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void; + + #[cfg(not(all(target_os = "linux", target_arch = "s390x")))] + // This function is a misnomer: rather than getting this frame's + // Canonical Frame Address (aka the caller frame's SP) it + // returns this frame's SP. + // + // https://github.com/libunwind/libunwind/blob/d32956507cf29d9b1a98a8bce53c78623908f4fe/src/unwind/GetCFA.c#L28-L35 + #[link_name = "_Unwind_GetCFA"] + pub fn get_sp(ctx: *mut _Unwind_Context) -> libc::uintptr_t; + + } + + // s390x uses a biased CFA value, therefore we need to use + // _Unwind_GetGR to get the stack pointer register (%r15) + // instead of relying on _Unwind_GetCFA. + #[cfg(all(target_os = "linux", target_arch = "s390x"))] + pub unsafe fn get_sp(ctx: *mut _Unwind_Context) -> libc::uintptr_t { + extern "C" { + pub fn _Unwind_GetGR(ctx: *mut _Unwind_Context, index: libc::c_int) -> libc::uintptr_t; + } + _Unwind_GetGR(ctx, 15) + } + } else { + // On android and arm, the function `_Unwind_GetIP` and a bunch of + // others are macros, so we define functions containing the + // expansion of the macros. + // + // TODO: link to the header file that defines these macros, if you + // can find it. (I, fitzgen, cannot find the header file that some + // of these macro expansions were originally borrowed from.) + #[repr(C)] + enum _Unwind_VRS_Result { + _UVRSR_OK = 0, + _UVRSR_NOT_IMPLEMENTED = 1, + _UVRSR_FAILED = 2, + } + #[repr(C)] + enum _Unwind_VRS_RegClass { + _UVRSC_CORE = 0, + _UVRSC_VFP = 1, + _UVRSC_FPA = 2, + _UVRSC_WMMXD = 3, + _UVRSC_WMMXC = 4, + } + #[repr(C)] + enum _Unwind_VRS_DataRepresentation { + _UVRSD_UINT32 = 0, + _UVRSD_VFPX = 1, + _UVRSD_FPAX = 2, + _UVRSD_UINT64 = 3, + _UVRSD_FLOAT = 4, + _UVRSD_DOUBLE = 5, + } + + type _Unwind_Word = libc::c_uint; + extern "C" { + fn _Unwind_VRS_Get( + ctx: *mut _Unwind_Context, + klass: _Unwind_VRS_RegClass, + word: _Unwind_Word, + repr: _Unwind_VRS_DataRepresentation, + data: *mut c_void, + ) -> _Unwind_VRS_Result; + } + + pub unsafe fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> libc::uintptr_t { + let mut val: _Unwind_Word = 0; + let ptr = &mut val as *mut _Unwind_Word; + let _ = _Unwind_VRS_Get( + ctx, + _Unwind_VRS_RegClass::_UVRSC_CORE, + 15, + _Unwind_VRS_DataRepresentation::_UVRSD_UINT32, + ptr as *mut c_void, + ); + (val & !1) as libc::uintptr_t + } + + // R13 is the stack pointer on arm. + const SP: _Unwind_Word = 13; + + pub unsafe fn get_sp(ctx: *mut _Unwind_Context) -> libc::uintptr_t { + let mut val: _Unwind_Word = 0; + let ptr = &mut val as *mut _Unwind_Word; + let _ = _Unwind_VRS_Get( + ctx, + _Unwind_VRS_RegClass::_UVRSC_CORE, + SP, + _Unwind_VRS_DataRepresentation::_UVRSD_UINT32, + ptr as *mut c_void, + ); + val as libc::uintptr_t + } + + // This function also doesn't exist on Android or ARM/Linux, so make it + // a no-op. + pub unsafe fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void { + pc + } + } + } +} diff --git a/library/backtrace/src/backtrace/miri.rs b/library/backtrace/src/backtrace/miri.rs new file mode 100644 index 000000000..9a5f65b80 --- /dev/null +++ b/library/backtrace/src/backtrace/miri.rs @@ -0,0 +1,107 @@ +use alloc::boxed::Box; +use alloc::vec::Vec; +use core::ffi::c_void; + +extern "Rust" { + fn miri_backtrace_size(flags: u64) -> usize; + fn miri_get_backtrace(flags: u64, buf: *mut *mut ()); + fn miri_resolve_frame(ptr: *mut (), flags: u64) -> MiriFrame; + fn miri_resolve_frame_names(ptr: *mut (), flags: u64, name_buf: *mut u8, filename_buf: *mut u8); +} + +#[repr(C)] +pub struct MiriFrame { + pub name_len: usize, + pub filename_len: usize, + pub lineno: u32, + pub colno: u32, + pub fn_ptr: *mut c_void, +} + +#[derive(Clone, Debug)] +pub struct FullMiriFrame { + pub name: Box<[u8]>, + pub filename: Box<[u8]>, + pub lineno: u32, + pub colno: u32, + pub fn_ptr: *mut c_void, +} + +#[derive(Debug, Clone)] +pub struct Frame { + pub addr: *mut c_void, + pub inner: FullMiriFrame, +} + +// SAFETY: Miri guarantees that the returned pointer +// can be used from any thread. +unsafe impl Send for Frame {} +unsafe impl Sync for Frame {} + +impl Frame { + pub fn ip(&self) -> *mut c_void { + self.addr + } + + pub fn sp(&self) -> *mut c_void { + core::ptr::null_mut() + } + + pub fn symbol_address(&self) -> *mut c_void { + self.inner.fn_ptr + } + + pub fn module_base_address(&self) -> Option<*mut c_void> { + None + } +} + +pub fn trace<F: FnMut(&super::Frame) -> bool>(cb: F) { + // SAFETY: Miri guarantees that the backtrace API functions + // can be called from any thread. + unsafe { trace_unsynchronized(cb) }; +} + +pub fn resolve_addr(ptr: *mut c_void) -> Frame { + // SAFETY: Miri will stop execution with an error if this pointer + // is invalid. + let frame = unsafe { miri_resolve_frame(ptr as *mut (), 1) }; + + let mut name = Vec::with_capacity(frame.name_len); + let mut filename = Vec::with_capacity(frame.filename_len); + + // SAFETY: name and filename have been allocated with the amount + // of memory miri has asked for, and miri guarantees it will initialize it + unsafe { + miri_resolve_frame_names(ptr as *mut (), 0, name.as_mut_ptr(), filename.as_mut_ptr()); + + name.set_len(frame.name_len); + filename.set_len(frame.filename_len); + } + + Frame { + addr: ptr, + inner: FullMiriFrame { + name: name.into(), + filename: filename.into(), + lineno: frame.lineno, + colno: frame.colno, + fn_ptr: frame.fn_ptr, + }, + } +} + +pub unsafe fn trace_unsynchronized<F: FnMut(&super::Frame) -> bool>(mut cb: F) { + let len = miri_backtrace_size(0); + + let mut frames = Vec::with_capacity(len); + + miri_get_backtrace(1, frames.as_mut_ptr()); + + frames.set_len(len); + + for ptr in frames.iter() { + let frame = resolve_addr(*ptr as *mut c_void); + cb(&super::Frame { inner: frame }); + } +} diff --git a/library/backtrace/src/backtrace/mod.rs b/library/backtrace/src/backtrace/mod.rs new file mode 100644 index 000000000..93355d744 --- /dev/null +++ b/library/backtrace/src/backtrace/mod.rs @@ -0,0 +1,162 @@ +use core::ffi::c_void; +use core::fmt; + +/// Inspects the current call-stack, passing all active frames into the closure +/// provided to calculate a stack trace. +/// +/// This function is the workhorse of this library in calculating the stack +/// traces for a program. The given closure `cb` is yielded instances of a +/// `Frame` which represent information about that call frame on the stack. The +/// closure is yielded frames in a top-down fashion (most recently called +/// functions first). +/// +/// The closure's return value is an indication of whether the backtrace should +/// continue. A return value of `false` will terminate the backtrace and return +/// immediately. +/// +/// Once a `Frame` is acquired you will likely want to call `backtrace::resolve` +/// to convert the `ip` (instruction pointer) or symbol address to a `Symbol` +/// through which the name and/or filename/line number can be learned. +/// +/// Note that this is a relatively low-level function and if you'd like to, for +/// example, capture a backtrace to be inspected later, then the `Backtrace` +/// type may be more appropriate. +/// +/// # Required features +/// +/// This function requires the `std` feature of the `backtrace` crate to be +/// enabled, and the `std` feature is enabled by default. +/// +/// # Panics +/// +/// This function strives to never panic, but if the `cb` provided panics then +/// some platforms will force a double panic to abort the process. Some +/// platforms use a C library which internally uses callbacks which cannot be +/// unwound through, so panicking from `cb` may trigger a process abort. +/// +/// # Example +/// +/// ``` +/// extern crate backtrace; +/// +/// fn main() { +/// backtrace::trace(|frame| { +/// // ... +/// +/// true // continue the backtrace +/// }); +/// } +/// ``` +#[cfg(feature = "std")] +pub fn trace<F: FnMut(&Frame) -> bool>(cb: F) { + let _guard = crate::lock::lock(); + unsafe { trace_unsynchronized(cb) } +} + +/// Same as `trace`, only unsafe as it's unsynchronized. +/// +/// This function does not have synchronization guarantees but is available +/// when the `std` feature of this crate isn't compiled in. See the `trace` +/// function for more documentation and examples. +/// +/// # Panics +/// +/// See information on `trace` for caveats on `cb` panicking. +pub unsafe fn trace_unsynchronized<F: FnMut(&Frame) -> bool>(mut cb: F) { + trace_imp(&mut cb) +} + +/// A trait representing one frame of a backtrace, yielded to the `trace` +/// function of this crate. +/// +/// The tracing function's closure will be yielded frames, and the frame is +/// virtually dispatched as the underlying implementation is not always known +/// until runtime. +#[derive(Clone)] +pub struct Frame { + pub(crate) inner: FrameImp, +} + +impl Frame { + /// Returns the current instruction pointer of this frame. + /// + /// This is normally the next instruction to execute in the frame, but not + /// all implementations list this with 100% accuracy (but it's generally + /// pretty close). + /// + /// It is recommended to pass this value to `backtrace::resolve` to turn it + /// into a symbol name. + pub fn ip(&self) -> *mut c_void { + self.inner.ip() + } + + /// Returns the current stack pointer of this frame. + /// + /// In the case that a backend cannot recover the stack pointer for this + /// frame, a null pointer is returned. + pub fn sp(&self) -> *mut c_void { + self.inner.sp() + } + + /// Returns the starting symbol address of the frame of this function. + /// + /// This will attempt to rewind the instruction pointer returned by `ip` to + /// the start of the function, returning that value. In some cases, however, + /// backends will just return `ip` from this function. + /// + /// The returned value can sometimes be used if `backtrace::resolve` failed + /// on the `ip` given above. + pub fn symbol_address(&self) -> *mut c_void { + self.inner.symbol_address() + } + + /// Returns the base address of the module to which the frame belongs. + pub fn module_base_address(&self) -> Option<*mut c_void> { + self.inner.module_base_address() + } +} + +impl fmt::Debug for Frame { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("Frame") + .field("ip", &self.ip()) + .field("symbol_address", &self.symbol_address()) + .finish() + } +} + +cfg_if::cfg_if! { + // This needs to come first, to ensure that + // Miri takes priority over the host platform + if #[cfg(miri)] { + pub(crate) mod miri; + use self::miri::trace as trace_imp; + pub(crate) use self::miri::Frame as FrameImp; + } else if #[cfg( + any( + all( + unix, + not(target_os = "emscripten"), + not(all(target_os = "ios", target_arch = "arm")), + ), + all( + target_env = "sgx", + target_vendor = "fortanix", + ), + ) + )] { + mod libunwind; + use self::libunwind::trace as trace_imp; + pub(crate) use self::libunwind::Frame as FrameImp; + } else if #[cfg(all(windows, not(target_vendor = "uwp")))] { + mod dbghelp; + use self::dbghelp::trace as trace_imp; + pub(crate) use self::dbghelp::Frame as FrameImp; + #[cfg(target_env = "msvc")] // only used in dbghelp symbolize + pub(crate) use self::dbghelp::StackFrame; + } else { + mod noop; + use self::noop::trace as trace_imp; + pub(crate) use self::noop::Frame as FrameImp; + } +} diff --git a/library/backtrace/src/backtrace/noop.rs b/library/backtrace/src/backtrace/noop.rs new file mode 100644 index 000000000..7bcea67aa --- /dev/null +++ b/library/backtrace/src/backtrace/noop.rs @@ -0,0 +1,28 @@ +//! Empty implementation of unwinding used when no other implementation is +//! appropriate. + +use core::ffi::c_void; + +#[inline(always)] +pub fn trace(_cb: &mut dyn FnMut(&super::Frame) -> bool) {} + +#[derive(Clone)] +pub struct Frame; + +impl Frame { + pub fn ip(&self) -> *mut c_void { + 0 as *mut _ + } + + pub fn sp(&self) -> *mut c_void { + 0 as *mut _ + } + + pub fn symbol_address(&self) -> *mut c_void { + 0 as *mut _ + } + + pub fn module_base_address(&self) -> Option<*mut c_void> { + None + } +} |