Add InternetError exception.

4 files changed, 122 insertions, 61 deletions

diff --git a/c/data.cpp b/c/data.cpp
index 771e6fb..e260209 100644
--- a/c/data.cpp
+++ b/c/data.cpp
@@ -6,46 +6,45 @@
 #include <libxml/xpath.h>
 
 #include "data.h"
+#include "win.h"
 
 struct InternetFile
 {
-	InternetFile(const wchar_t* url);
-	~InternetFile();
-	DWORD Read(void* buf, DWORD cb);
-	HINTERNET hi;
-	HINTERNET hiUrl;
-};
+	InternetFile(const wchar_t* url)
+	{
+		hi = InternetOpen(L"Episode Browser",
+		    INTERNET_OPEN_TYPE_DIRECT, nullptr, nullptr,
+		    /*INTERNET_FLAG_ASYNC*/0);
+		if (!hi)
+			throw Win32Error{};
+
+		hiUrl = InternetOpenUrl(hi, url,
+		    nullptr, 0, INTERNET_FLAG_NO_UI, 0);
+		if (!hiUrl) {
+			DWORD e = GetLastError();
+			InternetCloseHandle(hi);
+			throw InternetError(e);
+		}
+	}
 
-InternetFile::InternetFile(const wchar_t* url)
-{
-	hi = InternetOpen(L"Episode Browser",
-	    INTERNET_OPEN_TYPE_DIRECT, nullptr, nullptr,
-	    /*INTERNET_FLAG_ASYNC*/0);
-	if (!hi)
-		throw Win32Error{};
-
-	hiUrl = InternetOpenUrl(hi, url,
-	    nullptr, 0, INTERNET_FLAG_NO_UI, 0);
-	if (!hiUrl) {
+	~InternetFile()
+	{
+		InternetCloseHandle(hiUrl);
 		InternetCloseHandle(hi);
-		throw Win32Error{};
 	}
-}
 
-InternetFile::~InternetFile()
-{
-	InternetCloseHandle(hiUrl);
-	InternetCloseHandle(hi);
-}
+	DWORD Read(void* buf, DWORD cb)
+	{
+		DWORD cbRead;
+		if (InternetReadFile(hiUrl, buf, cb, &cbRead))
+			return cbRead;
+		else
+			throw InternetError{};
+	}
 
-DWORD InternetFile::Read(void* buf, DWORD cb)
-{
-	DWORD cbRead;
-	if (InternetReadFile(hiUrl, buf, cb, &cbRead))
-		return cbRead;
-	else
-		throw Win32Error{};
-}
+	HINTERNET hi;
+	HINTERNET hiUrl;
+};
 
 template <auto F, typename T>
 struct XmlPtr
@@ -98,8 +97,8 @@ void FetchData()
 {
 	LIBXML_TEST_VERSION;
 
-	InternetFile inf{L"https://www.detectiveconanworld.com/wiki/Anime"};
-	//InternetFile inf{L"file://C:/Users/John/Desktop/dcw.html"};
+	InternetFile inf(L"https://www.detectiveconanworld.com/wiki/Anime");
+	//InternetFile inf(L"file://C:/Users/John/Desktop/dcw.html");
 	char buf[1024];
 
 	HtmlParserCtxtPtr ctxt = htmlCreatePushParserCtxt(nullptr, nullptr,
@@ -167,6 +166,6 @@ void WaitFetchData(bool* bDone) noexcept
 		*bDone = true;
 	} catch (...) {
 		*bDone = true;
-		ShowException(L"Remote data could not be fetched due to %s: %s", L"Error", MB_ICONWARNING);
+		ShowException(L"Remote data could not be fetched due to an error: %s", L"Error", MB_ICONWARNING);
 	}
 }
diff --git a/c/main.cpp b/c/main.cpp
index 73a89d4..0e6c839 100644
--- a/c/main.cpp
+++ b/c/main.cpp
@@ -81,7 +81,7 @@ static void UpdateTheme();
 
 void OnTerminate() noexcept
 {
-	ShowException(L"Episode Browser was terminated due to %s: %s", L"Fatal Error", MB_ICONERROR);
+	ShowException(L"Episode Browser was terminated due to an error: %s", L"Fatal Error", MB_ICONERROR);
 	_Exit(1);
 }
 
diff --git a/c/win.cpp b/c/win.cpp
index c7ce7ec..601f82c 100644
--- a/c/win.cpp
+++ b/c/win.cpp
@@ -2,6 +2,7 @@
 #include <string>
 #include <SWI-Prolog.h>
 #include <windows.h>
+#include <wininet.h>
 
 #include "pl.h"
 #include "util.h"
@@ -84,24 +85,29 @@ int EBMessageBox(const std::wstring_view text, const std::wstring_view caption,
 
 void ShowException(const wchar_t* const fmt, const wchar_t* const title, const UINT uType) noexcept
 {
-	const wchar_t* what = L"an exception";
-	WcharPtr why;
-
 	try {
 		std::rethrow_exception(std::current_exception());
         } catch (const term_t& t) {
-		what = L"a Prolog exception";
-		try { why = PlString(t); } catch (...) {}
-	} catch (const Win32Error& e) {
-		what = L"a Windows error";
-		try { why = WcharPtr::Copy(e.What()); } catch (...) {}
+		WcharPtr what = PlString(t);
+		std::wstring msg(wcslen(fmt)+wcslen(what), 0);
+		Swprintf(msg, fmt, static_cast<wchar_t*>(what));
+		EBMessageBox(msg, title, uType);
+	} catch (const WideException& e) {
+		std::wstring msg(wcslen(fmt)+wcslen(e.What()), 0);
+		Swprintf(msg, fmt, e.What());
+		EBMessageBox(msg, title, uType);
 	} catch (const std::exception& e) {
-		try { why = WcharPtr::FromNarrow(e.what()); } catch (...) {}
-	} catch (...) {}
+		auto what = WcharPtr::FromNarrow(e.what());
+		std::wstring msg(wcslen(fmt)+wcslen(what), 0);
+		Swprintf(msg, fmt, static_cast<wchar_t*>(what));
+		EBMessageBox(msg, title, uType);
+	} catch (...) {
+		const wchar_t* what = L"an unknown error occurred";
+		std::wstring msg(wcslen(fmt)+wcslen(what), 0);
+		Swprintf(msg, fmt, what);
+		EBMessageBox(msg, title, uType);
+	}
 
-	std::wstring msg(wcslen(fmt)+wcslen(what)+wcslen(why), 0);
-	Swprintf(msg, fmt, what, static_cast<wchar_t*>(why));
-	EBMessageBox(msg, title, uType);
 }
 
 int GetRelativeCursorPos(const HWND hWnd, POINT* const pt) noexcept
@@ -118,9 +124,6 @@ int GetRelativeCursorPos(const HWND hWnd, POINT* const pt) noexcept
 	return 1;
 }
 
-Win32Error::Win32Error() noexcept
-	: code(GetLastError()) {}
-
 Win32Error::Win32Error(const DWORD code) noexcept
 	: code(code) {}
 
@@ -136,25 +139,66 @@ const char* Win32Error::what() const noexcept
 {
 	if (!m_szMsg)
 		FormatMessageA(
-		    FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
-		    nullptr,
+		    FORMAT_MESSAGE_ALLOCATE_BUFFER
+		    |FORMAT_MESSAGE_FROM_SYSTEM
+		    |FORMAT_MESSAGE_FROM_HMODULE
+		    |FORMAT_MESSAGE_IGNORE_INSERTS,
+		    GetModuleHandle(L"wininet.dll"),
 		    code,
 		    MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
 		    (char*)&m_szMsg,
 		    0, nullptr);
-	return m_szMsg;
+	return m_szMsg? m_szMsg: "An unknown error occurred";
 }
 
 const wchar_t* Win32Error::What() const noexcept
 {
 	if (!m_wszMsg)
 		FormatMessage(
-		    FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
-		    nullptr,
+		    FORMAT_MESSAGE_ALLOCATE_BUFFER
+		    |FORMAT_MESSAGE_FROM_SYSTEM
+		    |FORMAT_MESSAGE_FROM_HMODULE
+		    |FORMAT_MESSAGE_IGNORE_INSERTS,
+		    GetModuleHandle(L"wininet.dll"),
 		    code,
 		    MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
 		    (wchar_t*)&m_wszMsg,
 		    0, nullptr);
+	return m_wszMsg? m_wszMsg: L"An unknown error occurred";
+}
+
+InternetError::InternetError(DWORD codeSystem)
+{
+	if (codeSystem != ERROR_INTERNET_EXTENDED_ERROR)
+		throw Win32Error{codeSystem};
+
+	DWORD len, cch;
+	InternetGetLastResponseInfo(&code, nullptr, &len);
+
+	cch = len+1;
+	m_szMsg = new char[cch];
+	if (!InternetGetLastResponseInfoA(&code, m_szMsg, &cch))
+		throw Win32Error{};
+
+	cch = len+1;
+	m_wszMsg = new wchar_t[cch];
+	if (!InternetGetLastResponseInfo(&code, m_wszMsg, &len))
+		throw Win32Error{};
+}
+
+InternetError::~InternetError()
+{
+	delete m_szMsg;
+	delete m_wszMsg;
+}
+
+const char* InternetError::what() const noexcept
+{
+	return m_szMsg;
+}
+
+const wchar_t* InternetError::What() const noexcept
+{
 	return m_wszMsg;
 }
 
diff --git a/c/win.h b/c/win.h
index ab5cf05..f5bda59 100644
--- a/c/win.h
+++ b/c/win.h
@@ -16,14 +16,32 @@ int GetRelativeCursorPos(HWND hWnd, POINT* pt) noexcept;
 /* Cached values from GetSystemMetrics. */
 template <int I> auto Metric = GetSystemMetrics(I);
 
+struct WideException : public std::exception
+{
+	virtual const char* what() const noexcept = 0;
+	virtual const wchar_t* What() const noexcept = 0;
+};
+
 /* Exception for Windows API errors. */
-struct Win32Error : public std::exception
+struct Win32Error : public WideException
 {
-	Win32Error() noexcept;
-	Win32Error(DWORD code) noexcept;
+	Win32Error(DWORD code = GetLastError()) noexcept;
 	~Win32Error() noexcept;
 	const char* what() const noexcept override;
-	const wchar_t* What() const noexcept;
+	const wchar_t* What() const noexcept override;
+	DWORD code;
+private:
+	char* m_szMsg = nullptr;
+	wchar_t* m_wszMsg = nullptr;
+};
+
+/* Exception for extended Wininet errors. */
+struct InternetError : public WideException
+{
+	InternetError(DWORD codeSystem = GetLastError());
+	~InternetError() noexcept;
+	const char* what() const noexcept override;
+	const wchar_t* What() const noexcept override;
 	DWORD code;
 private:
 	char* m_szMsg = nullptr;