Deduplicate FormatMessage UTF-16 to UTF-8 conversion code

Signed-off-by: Sven Strickroth <email@cs-ware.de>

2 files changed, 54 insertions, 0 deletions

diff --git a/src/win32/error.c b/src/win32/error.c
new file mode 100644
index 000000000..3851ff099
--- /dev/null
+++ b/src/win32/error.c
@@ -0,0 +1,41 @@
+/*
+ * 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"
+
+char *git_win32_get_error_message(DWORD error_code)
+{
+	LPWSTR lpMsgBuf = NULL;
+
+	if (!error_code)
+		return NULL;
+
+	if (FormatMessageW(
+				FORMAT_MESSAGE_ALLOCATE_BUFFER |
+				FORMAT_MESSAGE_FROM_SYSTEM |
+				FORMAT_MESSAGE_IGNORE_INSERTS,
+				NULL, error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+				(LPWSTR)&lpMsgBuf, 0, NULL)) {
+		int utf8_size = WideCharToMultiByte(CP_UTF8, 0, lpMsgBuf, -1, NULL, 0, NULL, NULL);
+
+		char *lpMsgBuf_utf8 = git__malloc(utf8_size * sizeof(char));
+		if (lpMsgBuf_utf8 == NULL) {
+			LocalFree(lpMsgBuf);
+			return NULL;
+		}
+		if (!WideCharToMultiByte(CP_UTF8, 0, lpMsgBuf, -1, lpMsgBuf_utf8, utf8_size, NULL, NULL)) {
+			LocalFree(lpMsgBuf);
+			git__free(lpMsgBuf_utf8);
+			return NULL;
+		}
+
+		LocalFree(lpMsgBuf);
+		return lpMsgBuf_utf8;
+	}
+	return NULL;
+}
diff --git a/src/win32/error.h b/src/win32/error.h
new file mode 100644
index 000000000..12947a2e6
--- /dev/null
+++ b/src/win32/error.h
@@ -0,0 +1,13 @@
+/*
+ * 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.
+ */
+
+#ifndef INCLUDE_git_win32_error_h__
+#define INCLUDE_git_win32_error_h__
+
+extern char *git_win32_get_error_message(DWORD error_code);
+
+#endif