Add Win32Error exception class.

3 files changed, 61 insertions, 31 deletions

diff --git a/c/common.cpp b/c/common.cpp
index dd84742..3a99769 100644
--- a/c/common.cpp
+++ b/c/common.cpp
@@ -29,11 +29,35 @@ TCHAR *TszFromSz(const char *sz, int iCp)
 	return tsz;
 }
 
+Win32Error::Win32Error(DWORD dwErr)
+{
+	m_dwErr = dwErr;
+	FormatMessageA(
+	    FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
+	    NULL,
+	    m_dwErr,
+	    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+	    (LPSTR)&m_szMsg,
+	    0, NULL
+	);
+}
+
+Win32Error::~Win32Error()
+{
+	if (m_szMsg)
+		HeapFree(GetProcessHeap(), 0, m_szMsg);
+}
+
+const char *Win32Error::what(void) const noexcept 
+{
+	return m_szMsg;
+}
+
 Library::Library(const TCHAR *tszLibrary)
 {
 	m_hModule = LoadLibrary(tszLibrary);
 	if (!m_hModule)
-		throw std::invalid_argument("Library not found.");
+		throw Win32Error(GetLastError());
 }
 
 Library::~Library()
diff --git a/c/defs.h b/c/defs.h
index 5a6a25a..102dce2 100644
--- a/c/defs.h
+++ b/c/defs.h
@@ -3,16 +3,26 @@
 
 #include <memory>
 #include <optional>
+#include <stdexcept>
 #include <windows.h>
 #include <commctrl.h>
 #include <SWI-Prolog.h>
 
 /* common.cpp */
 TCHAR *TszFromSz(const char *, int);
+struct Win32Error : public std::exception
+{
+	Win32Error(DWORD);
+	~Win32Error(void);
+	virtual const char *what(void) const noexcept override;
+private:
+	DWORD m_dwErr;
+	char *m_szMsg = NULL;
+};
 struct Library
 {
 	Library(const TCHAR *);
-	~Library();
+	~Library(void);
 	FARPROC GetProcAddress(const char *);
 private:
 	HMODULE m_hModule;
@@ -70,7 +80,7 @@ int Plx(const char *, const char *);
 struct Query
 {
 	Query(module_t ctx, predicate_t p, term_t t0);
-	~Query();
+	~Query(void);
 	int Cut();
 	int Close();
 	int NextSolution();
diff --git a/c/main.cpp b/c/main.cpp
index 90f828d..82c95ba 100644
--- a/c/main.cpp
+++ b/c/main.cpp
@@ -33,21 +33,18 @@ static void UpdateTheme(void);
 int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
     LPSTR lpCmdLine, INT nCmdShow)
 {
-	LPTSTR tszErr;
-
 	/* Exit gracefully on uncaught exception. */
 	std::set_terminate(OnTerminate);
 
 	/* Set constant values. */
-	if (auto upLib = try_make<Library>(TEXT("uxtheme.dll")))
-		if (upLib->GetProcAddress("SetWindowTheme")) {
+	if (auto opLib = try_make<Library>(TEXT("uxtheme.dll")))
+		if (opLib->GetProcAddress("SetWindowTheme"))
 			g_bThemes = 1;
-		}
 	g_cxVScroll = GetSystemMetrics(SM_CXVSCROLL);
 
 	/* Setup fonts. */
-	if (auto upLib = try_make<Library>(TEXT("User32.dll"))) {
-		if (upLib->GetProcAddress("SystemParametersInfo" WA)) {
+	if (auto opLib = try_make<Library>(TEXT("User32.dll"))) {
+		if (opLib->GetProcAddress("SystemParametersInfo" WA)) {
 			NONCLIENTMETRICS m;
 			m.cbSize = sizeof(NONCLIENTMETRICS);
 			SystemParametersInfo(SPI_GETNONCLIENTMETRICS, sizeof(NONCLIENTMETRICS), &m, 0);
@@ -63,18 +60,17 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 
 	/* Initialize Prolog. */
 	char *argv[] = { (char *)"EpisodeBrowser", NULL };
-	tszErr = TEXT("Could not initialize Prolog.");
-	if (!PL_initialise(1, argv)) goto f;
-	tszErr = TEXT("Could not attach databases.");
-	if (!Pl("track_episodes","attach")) goto f;
-	if (!Pl("episode_data","attach")) goto f;
+	if (!PL_initialise(1, argv))
+		throw std::runtime_error("Could not initialize Prolog.");
+	if (!Pl("track_episodes","attach") || !Pl("episode_data","attach"))
+		throw std::runtime_error("Could not attach databases.");
 
 	/* Initialize common controls, load menu and register window class. */
 	INITCOMMONCONTROLSEX icc;
 	icc.dwSize = sizeof(icc);
 	icc.dwICC = ICC_WIN95_CLASSES;
-	tszErr = TEXT("Could not initialize common controls.");
-	if (!InitCommonControlsEx(&icc)) goto f;
+	if (!InitCommonControlsEx(&icc))
+		throw std::runtime_error("Could not initialize common controls.");
 
 	g_hPopupMenu = LoadMenu(NULL, MAKEINTRESOURCE(IDR_POPUPMENU));
 	g_hPopupMenu = GetSubMenu(g_hPopupMenu, 0);
@@ -90,8 +86,8 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 	wc.lpszMenuName	 = MAKEINTRESOURCE(IDR_MENU);
 	wc.lpszClassName = TEXT("Episode Browser");
 	wc.hIconSm	 = LoadIcon(NULL, IDI_APPLICATION);
-	tszErr = TEXT("Could not register window class.");
-	if (!RegisterClassEx(&wc)) goto f;
+	if (!RegisterClassEx(&wc))
+		throw std::runtime_error("Could not register window class.");
 
 	/* Create window. Note that a CBT hook is used to initialize
 	 * important global variables before any messages are sent to
@@ -108,8 +104,7 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 	    NULL, NULL, hInstance, NULL
 	);
 	UnhookWindowsHookEx(hHook);
-	tszErr = TEXT("Could not create main window.");
-	if (!hWnd) goto f;
+	if (!hWnd) throw std::runtime_error("Could not create main window.");
 	g_hWndStatus = CreateStatusBar(hWnd, hInstance);
 	ShowWindow(hWnd, nCmdShow);
 
@@ -127,9 +122,6 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 
 	PL_halt(0);
 	return 0;
-f:	MessageBox(NULL, tszErr, TEXT("Fatal Error"), MB_ICONERROR);
-	PL_halt(1);
-	return 1;
 }
 
 void OnTerminate()
@@ -139,14 +131,18 @@ void OnTerminate()
         } catch (term_t &t) {
 		char *sz;
 		TCHAR *tsz;
-		if (PL_get_chars(t, &sz, CVT_WRITE)) /* TODO: PL_get_wchars */
-			tsz = TszFromSz(sz, CP_UTF8);
-		else
-			tsz = TEXT("The program was terminated due to an exception.");
-		MessageBox(NULL, tsz, TEXT("Fatal Error"), MB_ICONERROR);
+		/* TODO: PL_get_wchars */
+		if (PL_get_chars(t, &sz, CVT_WRITE) && (tsz = TszFromSz(sz, CP_UTF8))) {
+			MessageBox(NULL, tsz, TEXT("Fatal Error"), MB_ICONERROR);
+			free(tsz);
+		} else
+			MessageBoxA(NULL, "The program was terminated due to a Prolog exception.",
+			    "Fatal Error", MB_ICONERROR);
+	} catch (std::exception &e) {
+		MessageBoxA(NULL, e.what(), "Fatal Error", MB_ICONERROR);
 	} catch (...) {
-		MessageBox(NULL, TEXT("The program was terminated due to an exception."),
-		    TEXT("Fatal Error"), MB_ICONERROR);
+		MessageBoxA(NULL, "The program was terminated due to an exception.",
+		    "Fatal Error", MB_ICONERROR);
 	}
 	std::_Exit(1);
 }