fix: add a separate trace_thread function

Author: aminya

examples/other_thread.rs

@@ -1,7 +1,6 @@
 // Windows only currently
-use std::os::windows::prelude::AsRawHandle;
 use backtrace::{Backtrace, BacktraceFrame};
-
+use std::os::windows::prelude::AsRawHandle;
 
 fn worker() {
     foo();
@@ -18,22 +17,21 @@ fn baz() {
     //std::thread::sleep(std::time::Duration::from_millis(1000));
     loop {
         print!("");
-    };
+    }
 }
 
-
 fn main() {
     let thread = std::thread::spawn(|| {
         worker();
     });
     let os_handle = thread.as_raw_handle();
-    
+
     // Allow the thread to start
     std::thread::sleep(std::time::Duration::from_millis(100));
 
     let mut frames = Vec::new();
     unsafe {
-        backtrace::trace_thread_unsynchronized(os_handle,|frame| {
+        backtrace::trace_thread_unsynchronized(os_handle, |frame| {
             frames.push(BacktraceFrame::from(frame.clone()));
             true
         });

src/backtrace/dbghelp.rs

@@ -88,8 +88,14 @@ impl Frame {
 #[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, thread: *mut c_void) {
+#[inline(always)]
+pub unsafe fn trace(cb: &mut dyn FnMut(&super::Frame) -> bool) {
+    let thread = GetCurrentThread();
+    trace_thread(cb, thread)
+}
+
+#[inline(always)]
+pub unsafe fn trace_thread(cb: &mut dyn FnMut(&super::Frame) -> bool, thread: *mut c_void) {
     // Allocate necessary structures for doing the stack walk
     let process = GetCurrentProcess();
 
@@ -112,12 +118,11 @@ pub unsafe fn trace(cb: &mut dyn FnMut(&super::Frame) -> bool, thread: *mut c_vo
             return;
         }
         let status = GetThreadContext(thread, &mut context.0);
-        if ResumeThread(thread) as i32 == -1 || status == 0{
+        if ResumeThread(thread) as i32 == -1 || status == 0 {
             return;
         }
     }
 
-
     // Ensure this process's symbols are initialized
     let dbghelp = match dbghelp::init() {
         Ok(dbghelp) => dbghelp,

src/backtrace/mod.rs

@@ -1,6 +1,8 @@
 use core::ffi::c_void;
 use core::fmt;
 
+use self::dbghelp::trace_thread;
+
 /// Inspects the current call-stack, passing all active frames into the closure
 /// provided to calculate a stack trace.
 ///
@@ -63,12 +65,25 @@ pub fn trace<F: FnMut(&Frame) -> bool>(cb: F) {
 ///
 /// 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, 0 as _)
+    trace_imp(&mut cb)
 }
 
-/// TODO docs
-pub unsafe fn trace_thread_unsynchronized<F: FnMut(&Frame) -> bool>(thread: *mut c_void, mut cb: F) {
-    trace_imp(&mut cb, thread)
+/// Similar to [trace_unsynchronized], but additionally, it supports tracing a thread other than the current thread.
+///
+/// The function gets the traced thread's handle as its first argument.
+///
+/// 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_thread_unsynchronized<F: FnMut(&Frame) -> bool>(
+    thread: *mut c_void,
+    mut cb: F,
+) {
+    trace_thread(&mut cb, thread)
 }
 
 /// A trait representing one frame of a backtrace, yielded to the `trace`

src/lib.rs

@@ -110,7 +110,7 @@ extern crate std;
 #[allow(unused_extern_crates)]
 extern crate alloc;
 
-pub use self::backtrace::{trace_unsynchronized, trace_thread_unsynchronized, Frame};
+pub use self::backtrace::{trace_thread_unsynchronized, trace_unsynchronized, Frame};
 mod backtrace;
 
 pub use self::symbolize::resolve_frame_unsynchronized;