efw: configure CRT error reporting

.github/workflows/ci.yml

@@ -276,6 +276,9 @@ jobs:
 
             // Get artifacts from this run
             const run_id = workflow_runs.data.workflow_runs[0].id;
+            const run_url = workflow_runs.data.workflow_runs[0].html_url;
+            console.log(`Using workflow run: ${run_url}`);
+
             const artifacts = await github.rest.actions.listWorkflowRunArtifacts({
               owner: 'microsoft',
               repo: 'ebpf-for-windows',

internal/efw/error_reporting.go

@@ -0,0 +1,155 @@
+//go:build windows
+
+package efw
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"syscall"
+	"testing"
+
+	"golang.org/x/sys/windows"
+)
+
+func init() {
+	if !testing.Testing() {
+		return
+	}
+
+	if isDebuggerPresent() {
+		return
+	}
+
+	if err := configureCRTErrorReporting(); err != nil {
+		fmt.Fprintln(os.Stderr, "WARNING: Could not configure CRT error reporting, tests may hang:", err)
+	}
+}
+
+var errErrorReportingAlreadyConfigured = errors.New("error reporting already configured")
+
+// Configure built-in error reporting of the C runtime library.
+//
+// The C runtime emits assertion failures into a graphical message box by default.
+// This causes a hang in CI environments. This function configures the CRT to
+// log to stderr instead.
+func configureCRTErrorReporting() error {
+	const ucrtDebug = "ucrtbased.dll"
+
+	// Constants from crtdbg.h
+	//
+	// See https://doxygen.reactos.org/da/d40/crt_2crtdbg_8h_source.html
+	const (
+		_CRT_ERROR          = 1
+		_CRT_ASSERT         = 2
+		_CRTDBG_MODE_FILE   = 0x1
+		_CRTDBG_MODE_WNDW   = 0x4
+		_CRTDBG_HFILE_ERROR = -2
+		_CRTDBG_FILE_STDERR = -4
+	)
+
+	// Load the efW API to trigger loading the CRT. This may fail, in which case
+	// we can't figure out which CRT is being used.
+	// In that case we rely on the error bubbling up via some other path.
+	_ = module.Load()
+
+	ucrtHandle, err := syscall.UTF16PtrFromString(ucrtDebug)
+	if err != nil {
+		return err
+	}
+
+	var handle windows.Handle
+	err = windows.GetModuleHandleEx(0, ucrtHandle, &handle)
+	if errors.Is(err, windows.ERROR_MOD_NOT_FOUND) {
+		// Loading the ebpf api did not pull in the debug UCRT, so there is
+		// nothing to configure.
+		return nil
+	} else if err != nil {
+		return err
+	}
+	defer windows.FreeLibrary(handle)
+
+	setReportModeAddr, err := windows.GetProcAddress(handle, "_CrtSetReportMode")
+	if err != nil {
+		return err
+	}
+
+	setReportMode := func(reportType int, reportMode int) (int, error) {
+		// See https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/crtsetreportmode?view=msvc-170
+		r1, _, err := syscall.SyscallN(setReportModeAddr, uintptr(reportType), uintptr(reportMode))
+		if int(r1) == -1 {
+			return 0, fmt.Errorf("set report mode for type %d: %w", reportType, err)
+		}
+		return int(r1), nil
+	}
+
+	setReportFileAddr, err := windows.GetProcAddress(handle, "_CrtSetReportFile")
+	if err != nil {
+		return err
+	}
+
+	setReportFile := func(reportType int, reportFile int) (int, error) {
+		// See https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/crtsetreportfile?view=msvc-170
+		r1, _, err := syscall.SyscallN(setReportFileAddr, uintptr(reportType), uintptr(reportFile))
+		if int(r1) == _CRTDBG_HFILE_ERROR {
+			return 0, fmt.Errorf("set report file for type %d: %w", reportType, err)
+		}
+		return int(r1), nil
+	}
+
+	reportToFile := func(reportType, defaultMode int) error {
+		oldMode, err := setReportMode(reportType, _CRTDBG_MODE_FILE)
+		if err != nil {
+			return err
+		}
+
+		if oldMode != defaultMode {
+			// Attempt to restore old mode if it was different from the expected default.
+			_, _ = setReportMode(reportType, oldMode)
+			return errErrorReportingAlreadyConfigured
+		}
+
+		oldFile, err := setReportFile(reportType, _CRTDBG_FILE_STDERR)
+		if err != nil {
+			return err
+		}
+
+		if oldFile != -1 {
+			// Attempt to restore old file if it was different from the expected default.
+			_, _ = setReportFile(reportType, oldFile)
+			return errErrorReportingAlreadyConfigured
+		}
+
+		return nil
+	}
+
+	// See https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/crtsetreportmode?view=msvc-170#remarks
+	// for defaults.
+	if err := reportToFile(_CRT_ASSERT, _CRTDBG_MODE_WNDW); err != nil {
+		return err
+	}
+
+	if err := reportToFile(_CRT_ERROR, _CRTDBG_MODE_WNDW); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// isDebuggerPresent returns true if the current process is being debugged.
+//
+// See https://learn.microsoft.com/en-us/windows/win32/api/debugapi/nf-debugapi-isdebuggerpresent
+func isDebuggerPresent() bool {
+	kernel32Handle, err := windows.LoadLibrary("kernel32.dll")
+	if err != nil {
+		return false
+	}
+
+	isDebuggerPresentAddr, err := windows.GetProcAddress(kernel32Handle, "IsDebuggerPresent")
+	if err != nil {
+		return false
+	}
+
+	r1, _, _ := syscall.SyscallN(isDebuggerPresentAddr)
+	return r1 != 0
+}

internal/efw/error_reporting_test.go

@@ -0,0 +1,17 @@
+//go:build windows
+
+package efw
+
+import (
+	"testing"
+
+	"github.com/go-quicktest/qt"
+)
+
+func TestConfigureErrorReporting(t *testing.T) {
+	qt.Assert(t, qt.ErrorIs(configureCRTErrorReporting(), errErrorReportingAlreadyConfigured))
+}
+
+func TestIsDebuggerPresent(t *testing.T) {
+	qt.Assert(t, qt.IsFalse(isDebuggerPresent()))
+}