[lldb] Inherit DuplicateFileAction(HANDLE, HANDLE) handles on windows

This is a follow-up to llvm#126935, which enables passing handles to a child
process on windows systems. Unlike on unix-like systems, the handles
need to be created with the "inheritable" flag because ...

Author: labath

lldb/source/Host/windows/ProcessLauncherWindows.cpp

@@ -10,6 +10,7 @@
 #include "lldb/Host/HostProcess.h"
 #include "lldb/Host/ProcessLaunchInfo.h"
 
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/Program.h"
@@ -65,12 +66,21 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
 
   std::string executable;
   std::vector<char> environment;
-  STARTUPINFO startupinfo = {};
+  STARTUPINFOEX startupinfoex = {};
+  STARTUPINFO &startupinfo = startupinfoex.StartupInfo;
   PROCESS_INFORMATION pi = {};
 
   HANDLE stdin_handle = GetStdioHandle(launch_info, STDIN_FILENO);
   HANDLE stdout_handle = GetStdioHandle(launch_info, STDOUT_FILENO);
   HANDLE stderr_handle = GetStdioHandle(launch_info, STDERR_FILENO);
+  auto close_handles = llvm::make_scope_exit([&] {
+    if (stdin_handle)
+      ::CloseHandle(stdin_handle);
+    if (stdout_handle)
+      ::CloseHandle(stdout_handle);
+    if (stderr_handle)
+      ::CloseHandle(stderr_handle);
+  });
 
   startupinfo.cb = sizeof(startupinfo);
   startupinfo.dwFlags |= STARTF_USESTDHANDLES;
@@ -81,6 +91,40 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
   startupinfo.hStdOutput =
       stdout_handle ? stdout_handle : ::GetStdHandle(STD_OUTPUT_HANDLE);
 
+  size_t attributelist_size = 0;
+  InitializeProcThreadAttributeList(/*lpAttributeList=*/nullptr,
+                                    /*dwAttributeCount=*/1, /*dwFlags=*/0,
+                                    &attributelist_size);
+
+  startupinfoex.lpAttributeList =
+      static_cast<LPPROC_THREAD_ATTRIBUTE_LIST>(malloc(attributelist_size));
+  auto free_attributelist =
+      llvm::make_scope_exit([&] { free(startupinfoex.lpAttributeList); });
+  if (!InitializeProcThreadAttributeList(startupinfoex.lpAttributeList,
+                                         /*dwAttributeCount=*/1, /*dwFlags=*/0,
+                                         &attributelist_size)) {
+    error = Status(::GetLastError(), eErrorTypeWin32);
+    return HostProcess();
+  }
+  auto delete_attributelist = llvm::make_scope_exit(
+      [&] { DeleteProcThreadAttributeList(startupinfoex.lpAttributeList); });
+  std::vector<HANDLE> inherited_handles;
+  for (size_t i = 0; i < launch_info.GetNumFileActions(); ++i) {
+    const FileAction *act = launch_info.GetFileActionAtIndex(i);
+    if (act->GetAction() == FileAction::eFileActionDuplicate &&
+        act->GetFD() == act->GetActionArgument()) {
+      inherited_handles.push_back(act->GetFD());
+    }
+  }
+  if (!UpdateProcThreadAttribute(
+          attributelist_up.get(), /*dwFlags=*/0,
+          PROC_THREAD_ATTRIBUTE_HANDLE_LIST, inherited_handles.data(),
+          inherited_handles.size(),
+          /*lpPreviousValue=*/nullptr, /*lpReturnSize=*/nullptr)) {
+    error = Status(::GetLastError(), eErrorTypeWin32);
+    return HostProcess();
+  }
+
   const char *hide_console_var =
       getenv("LLDB_LAUNCH_INFERIORS_WITHOUT_CONSOLE");
   if (hide_console_var &&
@@ -89,7 +133,8 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
     startupinfo.wShowWindow = SW_HIDE;
   }
 
-  DWORD flags = CREATE_NEW_CONSOLE | CREATE_UNICODE_ENVIRONMENT;
+  DWORD flags = CREATE_NEW_CONSOLE | CREATE_UNICODE_ENVIRONMENT |
+                EXTENDED_STARTUPINFO_PRESENT;
   if (launch_info.GetFlags().Test(eLaunchFlagDebug))
     flags |= DEBUG_ONLY_THIS_PROCESS;
 
@@ -131,13 +176,6 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
     ::CloseHandle(pi.hThread);
   }
 
-  if (stdin_handle)
-    ::CloseHandle(stdin_handle);
-  if (stdout_handle)
-    ::CloseHandle(stdout_handle);
-  if (stderr_handle)
-    ::CloseHandle(stderr_handle);
-
   if (!result)
     return HostProcess();
 

lldb/unittests/Host/HostTest.cpp

@@ -59,7 +59,6 @@ TEST(Host, ProcessInstanceInfoCumulativeSystemTimeIsValid) {
   EXPECT_TRUE(info.CumulativeSystemTimeIsValid());
 }
 
-#ifdef LLVM_ON_UNIX
 TEST(Host, LaunchProcessDuplicatesHandle) {
   static constexpr llvm::StringLiteral test_msg("Hello subprocess!");
 
@@ -98,4 +97,3 @@ TEST(Host, LaunchProcessDuplicatesHandle) {
                     llvm::Succeeded());
   ASSERT_EQ(llvm::StringRef(msg, bytes_read), test_msg);
 }
-#endif