From f61e83d936ebab185b09682f922aa58734153761 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Fri, 15 Jul 2022 16:40:49 +0200
Subject: Add Win32Error exception class.

---
 c/common.cpp | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

(limited to 'c/common.cpp')

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()
-- 
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