gio: Add support for Windows DebugView logging v1 PROPOSED

Windows GUI programs close all stdin/stdout/stderr by default.
This
patch adds the native logging support provided by Windows.

mural (1):
  app/internal/log: add logger for Windows DbgView

 app/internal/log/log_windows.go | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 app/internal/log/log_windows.go

-- 
2.24.1

Thank you. Can you say something about where the debugging output end
up (I don't have much Windows development experience)? How will the
change affect programs that are not built with `-H windowsgui`?

Mura Li

1 year, 19 days ago

There is a tool named DebugView.exe that collects the log messages, which serves a similar role as logcat on Android. You can get it from the SysInternals: https://docs.microsoft.com/en-us/sysinternals/downloads/sysinternals-suite

As I tested it, if the program is built without '-H windowsgui', log.Printf will outputs to DebugView.exe but not to stdout.

On Thu Jan 9, 2020 at 3:43 PM, ~typeless wrote:

[PATCH gio 1/1] app/internal/log: add logger for Windows DbgView Export this patch

From: mural <mural@ctli.io>

---
 app/internal/log/log_windows.go | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 app/internal/log/log_windows.go

diff --git a/app/internal/log/log_windows.go b/app/internal/log/log_windows.go
new file mode 100644
index 0000000..0587fc9
--- /dev/null
+++ b/app/internal/log/log_windows.go
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// +build windows
+

Elias Naur

1 year, 19 days ago

You don't need the build tag. The file name is enough.

Next

+package log
+
+import (
+	"log"
+	"syscall"
+	"unsafe"
+)
+
+type logger struct{}
+
+var kernel32 = syscall.NewLazyDLL("kernel32")
+var outputDebugStringW = kernel32.NewProc("OutputDebugStringW")
+var out logger

Elias Naur

1 year, 19 days ago

Nit: Move into var ( ) group.

+
+func init() {
+	// Windows DbgView already includes timestamps.
+	log.SetFlags(log.Flags() &^ log.LstdFlags)
+	log.SetOutput(&out)
+}
+
+func (l *logger) Write(buf []byte) (int, error) {
+	p, err := syscall.UTF16PtrFromString(string(buf))
+	if err != nil {
+		return 0, err
+	}
+	outputDebugStringW.Call(uintptr(unsafe.Pointer(p)))
+	return len(buf), nil
+}
-- 
2.24.1

Elias Naur

1 year, 19 days ago

Thank you. Can you say something about where the debugging output end
up (I don't have much Windows development experience)? How will the
change affect programs that are not built with `-H windowsgui`?

On Thu Jan 9, 2020 at 3:43 PM, ~typeless wrote: