1 files changed, 77 insertions, 0 deletions
diff --git a/src/win32/error.c b/src/win32/error.c
new file mode 100644
index 000000000..4a9a0631f
--- /dev/null
+++ b/src/win32/error.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "common.h"
+#include "error.h"
+
+#ifdef GIT_WINHTTP
+# include <winhttp.h>
+#endif
+
+#define WC_ERR_INVALID_CHARS	0x80
+
+char *git_win32_get_error_message(DWORD error_code)
+{
+	LPWSTR lpMsgBuf = NULL;
+	HMODULE hModule = NULL;
+	char *utf8_msg = NULL;
+	int utf8_size;
+	DWORD dwFlags =
+		FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_IGNORE_INSERTS;
+
+	if (!error_code)
+		return NULL;
+
+#ifdef GIT_WINHTTP
+	/* Errors raised by WinHTTP are not in the system resource table */
+	if (error_code >= WINHTTP_ERROR_BASE &&
+		error_code <= WINHTTP_ERROR_LAST)
+		hModule = GetModuleHandleW(L"winhttp");
+#endif
+
+	GIT_UNUSED(hModule);
+
+	if (hModule)
+		dwFlags |= FORMAT_MESSAGE_FROM_HMODULE;
+	else
+		dwFlags |= FORMAT_MESSAGE_FROM_SYSTEM;
+
+	if (FormatMessageW(dwFlags, hModule, error_code,
+		MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+		(LPWSTR)&lpMsgBuf, 0, NULL)) {
+
+		/* Invalid code point check supported on Vista+ only */
+		if (git_has_win32_version(6, 0))
+			dwFlags = WC_ERR_INVALID_CHARS;
+		else
+			dwFlags = 0;
+
+		utf8_size = WideCharToMultiByte(CP_UTF8, dwFlags,
+			lpMsgBuf, -1, NULL, 0, NULL, NULL);
+
+		if (!utf8_size) {
+			assert(0);
+			goto on_error;
+		}
+
+		utf8_msg = git__malloc(utf8_size);
+
+		if (!utf8_msg)
+			goto on_error;
+
+		if (!WideCharToMultiByte(CP_UTF8, dwFlags,
+			lpMsgBuf, -1, utf8_msg, utf8_size, NULL, NULL)) {
+			git__free(utf8_msg);
+			goto on_error;
+		}
+
+on_error:
+		LocalFree(lpMsgBuf);
+	}
+
+	return utf8_msg;
+}