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GetCurrentProcess only once in win32 backtrace #735

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Merged
merged 2 commits into from
Sep 26, 2025
Merged

GetCurrentProcess only once in win32 backtrace #735

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e06b77e
GetCurrentProcess only once
workingjubilee Sep 25, 2025
d4738cc
deny(unsafe_op_in_unsafe_fn) in backtrace/win32.rs
workingjubilee Sep 25, 2025
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78 changes: 42 additions & 36 deletions src/backtrace/win32.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
//!
//! Note that all dbghelp support is loaded dynamically, see `src/dbghelp.rs`
//! for more information about that.
#![deny(unsafe_op_in_unsafe_fn)]

use super::super::{dbghelp, windows_sys::*};
use core::ffi::c_void;
Expand Down Expand Up @@ -97,11 +98,12 @@ 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 process = unsafe { GetCurrentProcess() };
let thread = unsafe { GetCurrentThread() };

let mut context = mem::zeroed::<MyContext>();
RtlCaptureContext(&mut context.0);
// This is a classic C-style out-ptr struct. Zero it to start.
let mut context = unsafe { mem::zeroed::<MyContext>() };
unsafe { RtlCaptureContext(&mut context.0) };

// Ensure this process's symbols are initialized
let dbghelp = match dbghelp::init() {
Expand All @@ -112,14 +114,13 @@ pub unsafe fn trace(cb: &mut dyn FnMut(&super::Frame) -> bool) {
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() {
match unsafe { (*dbghelp.dbghelp()).StackWalkEx() } {
#[allow(non_snake_case)]
Some(StackWalkEx) => {
let mut inner: STACKFRAME_EX = mem::zeroed();
// This is a classic C-style out-ptr struct. Zero it to start.
let mut inner: STACKFRAME_EX = unsafe { mem::zeroed() };
inner.StackFrameSize = mem::size_of::<STACKFRAME_EX>() as u32;
let mut frame = super::Frame {
inner: Frame {
Expand All @@ -133,20 +134,22 @@ pub unsafe fn trace(cb: &mut dyn FnMut(&super::Frame) -> bool) {
_ => unreachable!(),
};

while StackWalkEx(
image as u32,
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 _;
while unsafe {
StackWalkEx(
image as u32,
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 =
unsafe { get_module_base(process, frame.ip() as _) as _ };

if !cb(&frame) {
break;
Expand All @@ -156,7 +159,8 @@ pub unsafe fn trace(cb: &mut dyn FnMut(&super::Frame) -> bool) {
None => {
let mut frame = super::Frame {
inner: Frame {
stack_frame: StackFrame::Old(mem::zeroed()),
// This is a classic C-style out-ptr struct. Zero it to start.
stack_frame: StackFrame::Old(unsafe { mem::zeroed() }),
base_address: 0 as _,
},
};
Expand All @@ -166,19 +170,21 @@ pub unsafe fn trace(cb: &mut dyn FnMut(&super::Frame) -> bool) {
_ => unreachable!(),
};

while dbghelp.StackWalk64()(
image as u32,
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 _;
while unsafe {
dbghelp.StackWalk64()(
image as u32,
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 =
unsafe { get_module_base(process, frame.ip() as _) as _ };

if !cb(&frame) {
break;
Expand Down
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