1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! As always, windows has something very different than unix, we mainly want
12 //! to avoid having to depend too much on libunwind for windows.
14 //! If you google around, you'll find a fair bit of references to built-in
15 //! functions to get backtraces on windows. It turns out that most of these are
16 //! in an external library called dbghelp. I was unable to find this library
17 //! via `-ldbghelp`, but it is apparently normal to do the `dlopen` equivalent
20 //! You'll also find that there's a function called CaptureStackBackTrace
21 //! mentioned frequently (which is also easy to use), but sadly I didn't have a
22 //! copy of that function in my mingw install (maybe it was broken?). Instead,
23 //! this takes the route of using StackWalk64 in order to walk the stack.
25 #![allow(deprecated)] // dynamic_lib
29 use dynamic_lib::DynamicLibrary;
35 use sync::StaticMutex;
38 macro_rules! sym{ ($lib:expr, $e:expr, $t:ident) => (unsafe {
40 match lib.symbol($e) {
41 Ok(f) => $crate::mem::transmute::<*mut u8, $t>(f),
42 Err(..) => return Ok(())
46 #[cfg(target_env = "msvc")]
47 #[path = "printing/msvc.rs"]
50 #[cfg(target_env = "gnu")]
51 #[path = "printing/gnu.rs"]
54 type SymInitializeFn =
55 extern "system" fn(c::HANDLE, *mut c_void,
58 extern "system" fn(c::HANDLE) -> c::BOOL;
61 extern "system" fn(c::DWORD, c::HANDLE, c::HANDLE,
62 *mut c::STACKFRAME64, *mut c::CONTEXT,
63 *mut c_void, *mut c_void,
64 *mut c_void, *mut c_void) -> c::BOOL;
66 #[cfg(target_arch = "x86")]
67 pub fn init_frame(frame: &mut c::STACKFRAME64,
68 ctx: &c::CONTEXT) -> c::DWORD {
69 frame.AddrPC.Offset = ctx.Eip as u64;
70 frame.AddrPC.Mode = c::ADDRESS_MODE::AddrModeFlat;
71 frame.AddrStack.Offset = ctx.Esp as u64;
72 frame.AddrStack.Mode = c::ADDRESS_MODE::AddrModeFlat;
73 frame.AddrFrame.Offset = ctx.Ebp as u64;
74 frame.AddrFrame.Mode = c::ADDRESS_MODE::AddrModeFlat;
75 c::IMAGE_FILE_MACHINE_I386
78 #[cfg(target_arch = "x86_64")]
79 pub fn init_frame(frame: &mut c::STACKFRAME64,
80 ctx: &c::CONTEXT) -> c::DWORD {
81 frame.AddrPC.Offset = ctx.Rip as u64;
82 frame.AddrPC.Mode = c::ADDRESS_MODE::AddrModeFlat;
83 frame.AddrStack.Offset = ctx.Rsp as u64;
84 frame.AddrStack.Mode = c::ADDRESS_MODE::AddrModeFlat;
85 frame.AddrFrame.Offset = ctx.Rbp as u64;
86 frame.AddrFrame.Mode = c::ADDRESS_MODE::AddrModeFlat;
87 c::IMAGE_FILE_MACHINE_AMD64
92 SymCleanup: SymCleanupFn,
95 impl Drop for Cleanup {
96 fn drop(&mut self) { (self.SymCleanup)(self.handle); }
99 pub fn write(w: &mut Write) -> io::Result<()> {
100 // According to windows documentation, all dbghelp functions are
102 static LOCK: StaticMutex = StaticMutex::new();
103 let _g = LOCK.lock();
105 // Open up dbghelp.dll, we don't link to it explicitly because it can't
106 // always be found. Additionally, it's nice having fewer dependencies.
107 let path = Path::new("dbghelp.dll");
108 let dbghelp = match DynamicLibrary::open(Some(&path)) {
110 Err(..) => return Ok(()),
113 // Fetch the symbols necessary from dbghelp.dll
114 let SymInitialize = sym!(&dbghelp, "SymInitialize", SymInitializeFn);
115 let SymCleanup = sym!(&dbghelp, "SymCleanup", SymCleanupFn);
116 let StackWalk64 = sym!(&dbghelp, "StackWalk64", StackWalk64Fn);
118 // Allocate necessary structures for doing the stack walk
119 let process = unsafe { c::GetCurrentProcess() };
120 let thread = unsafe { c::GetCurrentThread() };
121 let mut context: c::CONTEXT = unsafe { mem::zeroed() };
122 unsafe { c::RtlCaptureContext(&mut context); }
123 let mut frame: c::STACKFRAME64 = unsafe { mem::zeroed() };
124 let image = init_frame(&mut frame, &context);
126 // Initialize this process's symbols
127 let ret = SymInitialize(process, ptr::null_mut(), c::TRUE);
128 if ret != c::TRUE { return Ok(()) }
129 let _c = Cleanup { handle: process, SymCleanup: SymCleanup };
131 // And now that we're done with all the setup, do the stack walking!
132 // Start from -1 to avoid printing this stack frame, which will
133 // always be exactly the same.
135 try!(write!(w, "stack backtrace:\n"));
136 while StackWalk64(image, process, thread, &mut frame, &mut context,
140 ptr::null_mut()) == c::TRUE {
141 let addr = frame.AddrPC.Offset;
142 if addr == frame.AddrReturn.Offset || addr == 0 ||
143 frame.AddrReturn.Offset == 0 { break }
148 try!(printing::print(w, i, addr-1, &dbghelp, process));