replay_gain_ape: parse replay gain from APE tags

Based on the APE reader.

src/replay_gain_ape.c

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2003-2010 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 "replay_gain_ape.h"
+#include "replay_gain_info.h"
+#include "ape.h"
+
+#include <glib.h>
+
+#include <string.h>
+#include <stdlib.h>
+
+struct rg_ape_ctx {
+	struct replay_gain_info *info;
+	bool found;
+};
+
+static bool
+replay_gain_ape_callback(unsigned long flags, const char *key,
+			 const char *_value, size_t value_length, void *_ctx)
+{
+	struct rg_ape_ctx *ctx = _ctx;
+
+	/* we only care about utf-8 text tags */
+	if ((flags & (0x3 << 1)) != 0)
+		return true;
+
+	char value[16];
+	if (value_length >= sizeof(value))
+		return true;
+	memcpy(value, _value, value_length);
+	value[value_length] = 0;
+
+	if (g_ascii_strcasecmp(key, "replaygain_track_gain") == 0) {
+		ctx->info->tuples[REPLAY_GAIN_TRACK].gain = atof(value);
+		ctx->found = true;
+	} else if (g_ascii_strcasecmp(key, "replaygain_album_gain") == 0) {
+		ctx->info->tuples[REPLAY_GAIN_ALBUM].gain = atof(value);
+		ctx->found = true;
+	} else if (g_ascii_strcasecmp(key, "replaygain_track_peak") == 0) {
+		ctx->info->tuples[REPLAY_GAIN_TRACK].peak = atof(value);
+		ctx->found = true;
+	} else if (g_ascii_strcasecmp(key, "replaygain_album_peak") == 0) {
+		ctx->info->tuples[REPLAY_GAIN_ALBUM].peak = atof(value);
+		ctx->found = true;
+	}
+
+	return true;
+}
+
+bool
+replay_gain_ape_read(const char *path_fs, struct replay_gain_info *info)
+{
+	struct rg_ape_ctx ctx = {
+		.info = info,
+		.found = false,
+	};
+
+	return tag_ape_scan(path_fs, replay_gain_ape_callback, &ctx) &&
+		ctx.found;
+}

src/replay_gain_ape.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2003-2010 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_REPLAY_GAIN_APE_H
+#define MPD_REPLAY_GAIN_APE_H
+
+#include "check.h"
+
+#include <stdbool.h>
+
+struct replay_gain_info;
+
+bool
+replay_gain_ape_read(const char *path_fs, struct replay_gain_info *info);
+
+#endif