Don't panic!

Cargo.toml

@@ -98,6 +98,8 @@ verify-winapi = [
   'winapi/tlhelp32',
   'winapi/winbase',
   'winapi/winnt',
+  'winapi/winnls',
+  'winapi/stringapiset',
 ]
 
 [[example]]

src/dbghelp.rs

@@ -376,16 +376,21 @@ pub fn init() -> Result<Init, ()> {
         DBGHELP.ensure_open()?;
 
         static mut INITIALIZED: bool = false;
-        if INITIALIZED {
-            return Ok(ret);
+        if !INITIALIZED {
+            set_optional_options();
+            INITIALIZED = true;
         }
-
-        let orig = DBGHELP.SymGetOptions().unwrap()();
+        Ok(ret)
+    }
+}
+fn set_optional_options() -> Option<()> {
+    unsafe {
+        let orig = DBGHELP.SymGetOptions()?();
 
         // Ensure that the `SYMOPT_DEFERRED_LOADS` flag is set, because
         // according to MSVC's own docs about this: "This is the fastest, most
         // efficient way to use the symbol handler.", so let's do that!
-        DBGHELP.SymSetOptions().unwrap()(orig | SYMOPT_DEFERRED_LOADS);
+        DBGHELP.SymSetOptions()?(orig | SYMOPT_DEFERRED_LOADS);
 
         // Actually initialize symbols with MSVC. Note that this can fail, but we
         // ignore it. There's not a ton of prior art for this per se, but LLVM
@@ -399,7 +404,7 @@ pub fn init() -> Result<Init, ()> {
         // the time, but now that it's using this crate it means that someone will
         // get to initialization first and the other will pick up that
         // initialization.
-        DBGHELP.SymInitializeW().unwrap()(GetCurrentProcess(), ptr::null_mut(), TRUE);
+        DBGHELP.SymInitializeW()?(GetCurrentProcess(), ptr::null_mut(), TRUE);
 
         // The default search path for dbghelp will only look in the current working
         // directory and (possibly) `_NT_SYMBOL_PATH` and `_NT_ALT_SYMBOL_PATH`.
@@ -413,7 +418,7 @@ pub fn init() -> Result<Init, ()> {
         search_path_buf.resize(1024, 0);
 
         // Prefill the buffer with the current search path.
-        if DBGHELP.SymGetSearchPathW().unwrap()(
+        if DBGHELP.SymGetSearchPathW()?(
             GetCurrentProcess(),
             search_path_buf.as_mut_ptr(),
             search_path_buf.len() as _,
@@ -433,7 +438,7 @@ pub fn init() -> Result<Init, ()> {
         let mut search_path = SearchPath::new(search_path_buf);
 
         // Update the search path to include the directory of the executable and each DLL.
-        DBGHELP.EnumerateLoadedModulesW64().unwrap()(
+        DBGHELP.EnumerateLoadedModulesW64()?(
             GetCurrentProcess(),
             Some(enum_loaded_modules_callback),
             ((&mut search_path) as *mut SearchPath) as *mut c_void,
@@ -442,11 +447,9 @@ pub fn init() -> Result<Init, ()> {
         let new_search_path = search_path.finalize();
 
         // Set the new search path.
-        DBGHELP.SymSetSearchPathW().unwrap()(GetCurrentProcess(), new_search_path.as_ptr());
-
-        INITIALIZED = true;
-        Ok(ret)
+        DBGHELP.SymSetSearchPathW()?(GetCurrentProcess(), new_search_path.as_ptr());
     }
+    Some(())
 }
 
 struct SearchPath {

src/symbolize/dbghelp.rs

@@ -19,7 +19,6 @@
 
 use super::super::{dbghelp, windows::*};
 use super::{BytesOrWideString, ResolveWhat, SymbolName};
-use core::char;
 use core::ffi::c_void;
 use core::marker;
 use core::mem;
@@ -91,7 +90,7 @@ pub unsafe fn resolve(what: ResolveWhat<'_>, cb: &mut dyn FnMut(&super::Symbol))
         ResolveWhat::Frame(frame) => {
             resolve_with_inline(&dbghelp, frame.ip(), frame.inner.inline_context(), cb)
         }
-    }
+    };
 }
 
 #[cfg(target_vendor = "win7")]
@@ -116,7 +115,7 @@ pub unsafe fn resolve(what: ResolveWhat<'_>, cb: &mut dyn FnMut(&super::Symbol))
         ResolveWhat::Frame(frame) => {
             resolve_inner(&dbghelp, frame.ip(), frame.inner.inline_context(), cb)
         }
-    }
+    };
 }
 
 /// Resolve the address using the legacy dbghelp API.
@@ -147,22 +146,28 @@ unsafe fn resolve_with_inline(
     addr: *mut c_void,
     inline_context: Option<DWORD>,
     cb: &mut dyn FnMut(&super::Symbol),
-) {
+) -> Option<()> {
     let current_process = GetCurrentProcess();
+    // Ensure we have the functions we need. Return if any aren't found.
+    let SymFromInlineContextW = (*dbghelp.dbghelp()).SymFromInlineContextW()?;
+    let SymGetLineFromInlineContextW = (*dbghelp.dbghelp()).SymGetLineFromInlineContextW()?;
 
     let addr = super::adjust_ip(addr) as DWORD64;
 
     let (inlined_frame_count, inline_context) = if let Some(ic) = inline_context {
         (0, ic)
     } else {
-        let mut inlined_frame_count = dbghelp.SymAddrIncludeInlineTrace()(current_process, addr);
+        let SymAddrIncludeInlineTrace = (*dbghelp.dbghelp()).SymAddrIncludeInlineTrace()?;
+        let SymQueryInlineTrace = (*dbghelp.dbghelp()).SymQueryInlineTrace()?;
+
+        let mut inlined_frame_count = SymAddrIncludeInlineTrace(current_process, addr);
 
         let mut inline_context = 0;
 
         // If there is are inlined frames but we can't load them for some reason OR if there are no
         // inlined frames, then we disregard inlined_frame_count and inline_context.
         if (inlined_frame_count > 0
-            && dbghelp.SymQueryInlineTrace()(
+            && SymQueryInlineTrace(
                 current_process,
                 addr,
                 0,
@@ -184,22 +189,14 @@ unsafe fn resolve_with_inline(
 
     for inline_context in inline_context..last_inline_context {
         do_resolve(
-            |info| {
-                dbghelp.SymFromInlineContextW()(current_process, addr, inline_context, &mut 0, info)
-            },
+            |info| SymFromInlineContextW(current_process, addr, inline_context, &mut 0, info),
             |line| {
-                dbghelp.SymGetLineFromInlineContextW()(
-                    current_process,
-                    addr,
-                    inline_context,
-                    0,
-                    &mut 0,
-                    line,
-                )
+                SymGetLineFromInlineContextW(current_process, addr, inline_context, 0, &mut 0, line)
             },
             cb,
         );
     }
+    Some(())
 }
 
 unsafe fn do_resolve(
@@ -225,26 +222,27 @@ unsafe fn do_resolve(
     // the real value.
     let name_len = ::core::cmp::min(info.NameLen as usize, info.MaxNameLen as usize - 1);
     let name_ptr = info.Name.as_ptr().cast::<u16>();
-    let name = slice::from_raw_parts(name_ptr, name_len);
 
     // Reencode the utf-16 symbol to utf-8 so we can use `SymbolName::new` like
     // all other platforms
-    let mut name_len = 0;
-    let mut name_buffer = [0; 256];
-    {
-        let mut remaining = &mut name_buffer[..];
-        for c in char::decode_utf16(name.iter().cloned()) {
-            let c = c.unwrap_or(char::REPLACEMENT_CHARACTER);
-            let len = c.len_utf8();
-            if len < remaining.len() {
-                c.encode_utf8(remaining);
-                let tmp = remaining;
-                remaining = &mut tmp[len..];
-                name_len += len;
-            } else {
-                break;
-            }
-        }
+    let mut name_buffer = [0_u8; 256];
+    let mut name_len = WideCharToMultiByte(
+        CP_UTF8,
+        0,
+        name_ptr,
+        name_len as i32,
+        name_buffer.as_mut_ptr().cast::<i8>(),
+        name_buffer.len() as i32,
+        core::ptr::null_mut(),
+        core::ptr::null_mut(),
+    ) as usize;
+    if name_len == 0 {
+        // If the returned length is zero that means the buffer wasn't big enough.
+        // However, the buffer will be filled with as much as will fit.
+        name_len = name_buffer.len();
+    } else if name_len > name_buffer.len() {
+        // This can't happen.
+        return;
     }
     let name = ptr::addr_of!(name_buffer[..name_len]);
 

src/windows.rs

@@ -38,6 +38,8 @@ cfg_if::cfg_if! {
             pub use winapi::um::tlhelp32::*;
             pub use winapi::um::winbase::*;
             pub use winapi::um::winnt::*;
+            pub use winapi::um::winnls::*;
+            pub use winapi::um::stringapiset::*;
 
             // Work around winapi not having this function on aarch64.
             #[cfg(target_arch = "aarch64")]
@@ -379,6 +381,7 @@ ffi! {
     pub const INVALID_HANDLE_VALUE: HANDLE = -1isize as HANDLE;
     pub const MAX_MODULE_NAME32: usize = 255;
     pub const MAX_PATH: usize = 260;
+    pub const CP_UTF8: u32 = 65001;
 
     pub type DWORD = u32;
     pub type PDWORD = *mut u32;
@@ -456,6 +459,16 @@ ffi! {
             lpme: LPMODULEENTRY32W,
         ) -> BOOL;
         pub fn lstrlenW(lpstring: PCWSTR) -> i32;
+        pub fn WideCharToMultiByte(
+            codepage: u32,
+            dwflags: u32,
+            lpwidecharstr: PCWSTR,
+            cchwidechar: i32,
+            lpmultibytestr: *mut i8,
+            cbmultibyte: i32,
+            lpdefaultchar: *const i8,
+            lpuseddefaultchar: *mut BOOL
+        ) -> i32;
     }
 }