The handle we pass to DbgHelp should meet the requirements of that library.

Author: grynspan

stdlib/public/runtime/ImageInspectionCOFF.cpp

@@ -47,16 +47,11 @@ int swift::lookupSymbol(const void *address, SymbolInfo *info) {
       return 0;
     }
 
-    char buffer[sizeof(SYMBOL_INFO) + kSymbolMaxNameLen];
-    PSYMBOL_INFO pSymbol = reinterpret_cast<PSYMBOL_INFO>(buffer);
+    SYMBOL_INFO_PACKAGE symbol = {};
     pSymbol->SizeOfStruct = sizeof(SYMBOL_INFO);
-    pSymbol->MaxNameLen = kSymbolMaxNameLen;
-
-    DWORD64 dwDisplacement = 0;
-
-    if (SymFromAddr(GetCurrentProcess(),
-                    reinterpret_cast<const DWORD64>(address),
-                    &dwDisplacement, pSymbol) == FALSE) {
+    pSymbol->MaxNameLen = MAX_SYM_NAME;
+    if (SymFromAddr(hProcess, reinterpret_cast<const DWORD64>(address),
+                    &nullptr, pSymbol) == FALSE) {
       return 0;
     }
 
@@ -83,7 +78,18 @@ void swift::_swift_withWin32DbgHelpLibrary(
     // now. This handle belongs to the Swift runtime and should not be closed by
     // `body` (or anybody else.)
     if (!dbgHelpHandle) {
-      dbgHelpHandle = HeapAlloc(GetProcessHeap(), 0, 1);
+      // Per the documentation for the Debug Help library, we should not use the
+      // current process handle because other subsystems might also use it and
+      // end up stomping on each other. So we'll try to duplicate that handle to
+      // get a unique one that still fulfills the needs of the library. If that
+      // fails (presumably because the current process doesn't have the
+      // PROCESS_DUP_HANDLE access right) then fall back to using the original
+      // process handle and hope nobody else is using it too.
+      HANDLE currentProcess = GetCurrentProcess();
+      if (!DuplicateHandle(currentProcess, currentProcess, currentProcess,
+                           &dbgHelpHandle, 0, false, DUPLICATE_SAME_ACCESS)) {
+        dbgHelpHandle = currentProcess;
+      }
     }
 
     // If we have not previously initialized the Debug Help library, do so now.
@@ -96,7 +102,7 @@ void swift::_swift_withWin32DbgHelpLibrary(
       // Set the library's options to what the Swift runtime generally expects.
       // If the options aren't going to change, we can skip the call and save a
       // few CPU cycles on the library call.
-      static constexpr const DWORD options = SYMOPT_UNDNAME | SYMOPT_DEFERRED_LOADS;
+      constexpr const DWORD options = SYMOPT_UNDNAME | SYMOPT_DEFERRED_LOADS;
       DWORD oldOptions = SymGetOptions();
       if (oldOptions != options) {
         SymSetOptions(options);