util/pidowner: new package to map from process ID to its user ID

util/pidowner/pidowner_windows.go

@@ -0,0 +1,32 @@
+package pidowner
+
+import (
+	"fmt"
+	"syscall"
+
+	"golang.org/x/sys/windows"
+)
+
+func ownerOfPID(pid int) (userID string, err error) {
+	procHnd, err := windows.OpenProcess(windows.PROCESS_QUERY_INFORMATION, false, uint32(pid))
+	if err == syscall.Errno(0x57) { // invalid parameter, for PIDs that don't exist
+		return "", ErrProcessNotFound
+	}
+	if err != nil {
+		return "", fmt.Errorf("OpenProcess: %T %#v", err, err)
+	}
+	defer windows.CloseHandle(procHnd)
+
+	var tok windows.Token
+	if err := windows.OpenProcessToken(procHnd, windows.TOKEN_QUERY, &tok); err != nil {
+		return "", fmt.Errorf("OpenProcessToken: %w", err)
+	}
+
+	tokUser, err := tok.GetTokenUser()
+	if err != nil {
+		return "", fmt.Errorf("GetTokenUser: %w", err)
+	}
+
+	sid := tokUser.User.Sid
+	return sid.String(), nil
+}