From dd0e555ba889a74ae14487ca0b4a5c62cfa4d873 Mon Sep 17 00:00:00 2001
From: Iain Patterson <me@iain.cx>
Date: Sun, 29 Dec 2013 17:29:21 +0000
Subject: [PATCH] Detect if we were double-clicked.
Because we are compiled as a console subsystem application, if the user
double-clicks the executable it will pop up a new console window. Then,
since no arguments were passed, we will dump a usage message which the
user won't have time to read, and exit.
We now detect this situation and redirect the usage message to a popup.
There are three likely cases to handle.
If we are running in a service context there won't be a console window.
GetConsoleWindow() will return a null handle.
If were launched from a command window, the process ID owning the
console handle will be different from as our process ID.
If the process IDs are the same, we were started with a new console. We
call FreeConsole() to close it and subsequently direct the usage message
to a message box.
---
event.cpp | 4 ++--
nssm.cpp | 25 ++++++++++++++++++++++++-
2 files changed, 26 insertions(+), 3 deletions(-)
diff --git a/event.cpp b/event.cpp
index 1313351..4af50a8 100644
--- a/event.cpp
+++ b/event.cpp
@@ -80,12 +80,12 @@ int popup_message(unsigned int type, unsigned long id, ...) {
return MessageBox(0, _T("The message which was supposed to go here is missing!"), NSSM, MB_OK | MB_ICONEXCLAMATION);
}
- TCHAR blurb[512];
+ TCHAR blurb[1024];
va_start(arg, id);
if (_vsntprintf_s(blurb, _countof(blurb), _TRUNCATE, format, arg) < 0) {
va_end(arg);
LocalFree(format);
- return MessageBox(0, _T("the message which was supposed to go here is too big!"), NSSM, MB_OK | MB_ICONEXCLAMATION);
+ return MessageBox(0, _T("The message which was supposed to go here is too big!"), NSSM, MB_OK | MB_ICONEXCLAMATION);
}
va_end(arg);
diff --git a/nssm.cpp b/nssm.cpp
index 7c95611..7e1e7ce 100644
--- a/nssm.cpp
+++ b/nssm.cpp
@@ -24,7 +24,8 @@ void strip_basename(TCHAR *buffer) {
/* How to use me correctly */
int usage(int ret) {
- print_message(stderr, NSSM_MESSAGE_USAGE, NSSM_VERSION, NSSM_DATE);
+ if (GetConsoleWindow()) print_message(stderr, NSSM_MESSAGE_USAGE, NSSM_VERSION, NSSM_DATE);
+ else popup_message(MB_OK, NSSM_MESSAGE_USAGE, NSSM_VERSION, NSSM_DATE);
return(ret);
}
@@ -39,7 +40,29 @@ void check_admin() {
FreeSid(AdministratorsGroup);
}
+/* See if we were launched from a console window. */
+static void check_console() {
+ /* If we're running in a service context there will be no console window. */
+ HWND console = GetConsoleWindow();
+ if (! console) return;
+
+ unsigned long pid;
+ if (! GetWindowThreadProcessId(console, &pid)) return;
+
+ /*
+ If the process associated with the console window handle is the same as
+ this process, we were not launched from an existing console. The user
+ probably double-clicked our executable.
+ */
+ if (GetCurrentProcessId() != pid) return;
+
+ /* We close our new console so that subsequent messages appear in a popup. */
+ FreeConsole();
+}
+
int _tmain(int argc, TCHAR **argv) {
+ check_console();
+
/* Remember if we are admin */
check_admin();
--
2.20.1