output/recorder: dynamic file name

src/tag/Format.cxx

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2003-2015 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 "Format.hxx"
+#include "Tag.hxx"
+#include "util/format.h"
+#include "util/StringUtil.hxx"
+
+#include <algorithm>
+
+#include <string.h>
+
+struct FormatTagContext {
+	const Tag &tag;
+
+	char buffer[256];
+
+	explicit FormatTagContext(const Tag &_tag):tag(_tag) {}
+};
+
+/**
+ * Is this a character unsafe to use in a path name segment?
+ */
+static constexpr bool
+IsUnsafeChar(char ch)
+{
+	return
+		/* disallow characters illegal in file names on
+		   Windows (Linux allows almost anything) */
+		ch == '\\' || ch == '/' || ch == ':' || ch == '*' ||
+		ch == '?' || ch == '<' || ch == '>' || ch == '|' ||
+		/* allow space, but disallow all other whitespace */
+		(unsigned char)ch < 0x20;
+}
+
+gcc_pure
+static bool
+HasUnsafeChar(const char *s)
+{
+	for (; *s; ++s)
+		if (IsUnsafeChar(*s))
+			return true;
+
+	return false;
+}
+
+static const char *
+SanitizeString(const char *s, char *buffer, size_t buffer_size)
+{
+	/* skip leading dots to avoid generating "../" sequences */
+	while (*s == '.')
+		++s;
+
+	if (!HasUnsafeChar(s))
+		return s;
+
+	char *end = CopyString(buffer, s, buffer_size);
+	std::replace_if(buffer, end, IsUnsafeChar, ' ');
+	return buffer;
+}
+
+gcc_pure gcc_nonnull_all
+static const char *
+TagGetter(const void *object, const char *name)
+{
+	const auto &_ctx = *(const FormatTagContext *)object;
+	auto &ctx = const_cast<FormatTagContext &>(_ctx);
+	const Tag &tag = ctx.tag;
+
+	TagType tag_type = tag_name_parse_i(name);
+	if (tag_type == TAG_NUM_OF_ITEM_TYPES)
+		/* unknown tag name */
+		return nullptr;
+
+	const char *value = tag.GetValue(tag_type);
+	if (value == nullptr)
+		/* known tag name, but not present in this object */
+		value = "";
+
+	// TODO: handle multiple tag values
+	return SanitizeString(value, ctx.buffer, sizeof(ctx.buffer));
+}
+
+char *
+FormatTag(const Tag &tag, const char *format)
+{
+	FormatTagContext ctx(tag);
+	return format_object(format, &ctx, TagGetter);
+}

src/tag/Format.hxx

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2003-2015 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.
+ */
+
+#ifndef MPD_TAG_FORMAT_HXX
+#define MPD_TAG_FORMAT_HXX
+
+#include "check.h"
+#include "Compiler.h"
+
+struct Tag;
+
+gcc_malloc gcc_nonnull_all
+char *
+FormatTag(const Tag &tag, const char *format);
+
+#endif