fs/Charset: move code to wrapper class IcuConverter

Prepare for a ICU-based backend without GLib.

src/lib/icu/Converter.cxx

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "Converter.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+
+#include <string.h>
+
+#ifdef HAVE_GLIB
+static constexpr Domain g_iconv_domain("g_iconv");
+#endif
+
+#ifdef HAVE_ICU_CONVERTER
+
+IcuConverter *
+IcuConverter::Create(const char *charset, Error &error)
+{
+	GIConv to = g_iconv_open("utf-8", charset);
+	GIConv from = g_iconv_open(charset, "utf-8");
+	if (to == (GIConv)-1 || from == (GIConv)-1) {
+		if (to != (GIConv)-1)
+			g_iconv_close(to);
+		if (from != (GIConv)-1)
+			g_iconv_close(from);
+		error.Format(g_iconv_domain,
+			     "Failed to initialize charset '%s'", charset);
+		return nullptr;
+	}
+
+	return new IcuConverter(to, from);
+}
+
+static std::string
+DoConvert(GIConv conv, const char *src)
+{
+	char buffer[4096];
+	char *in = const_cast<char *>(src);
+	char *out = buffer;
+	size_t in_left = strlen(src);
+	size_t out_left = sizeof(buffer);
+
+	size_t n = g_iconv(conv, &in, &in_left, &out, &out_left);
+
+	if (n == static_cast<size_t>(-1) || in_left > 0)
+		return std::string();
+
+	return std::string(buffer, sizeof(buffer) - out_left);
+}
+
+std::string
+IcuConverter::ToUTF8(const char *s) const
+{
+	return DoConvert(to_utf8, s);
+}
+
+std::string
+IcuConverter::FromUTF8(const char *s) const
+{
+	return DoConvert(from_utf8, s);
+}
+
+#endif