sticker: new library for storing dynamic information about songs

"Stickers" are pieces of information attached to existing MPD objects
(e.g. song files, directories, albums).  Clients can create arbitrary
name/value pairs.  MPD itself does not assume any special meaning in
them.

doc/mpd.conf.5

@@ -43,6 +43,10 @@ The default is "yes".
 .B db_file <file>
 This specifies where the db file will be stored.
 .TP
+.B sticker_file <file>
+The location of the sticker database.  This is a database which
+manages dynamic information attached to songs.
+.TP
 .B log_file <file>
 This specifies where the log file should be located.
 The special value "syslog" makes MPD use the local syslog daemon.

src/Makefile.am

@@ -100,6 +100,7 @@ mpd_headers = \
 	songvec.h \
 	state_file.h \
 	stats.h \
+	sticker.h \
 	tag.h \
 	tag_internal.h \
 	tag_pool.h \
@@ -192,6 +193,10 @@ mpd_SOURCES = \
 	stored_playlist.c \
 	timer.c
 
+if ENABLE_SQLITE
+mpd_SOURCES += sticker.c
+endif
+
 if HAVE_LIBSAMPLERATE
 mpd_SOURCES += pcm_resample_libsamplerate.c
 else

src/conf.c

@@ -172,6 +172,7 @@ void config_global_init(void)
 	registerConfigParam(CONF_FOLLOW_INSIDE_SYMLINKS,        0,     0);
 	registerConfigParam(CONF_FOLLOW_OUTSIDE_SYMLINKS,       0,     0);
 	registerConfigParam(CONF_DB_FILE,                       0,     0);
+	registerConfigParam(CONF_STICKER_FILE, false, false);
 	registerConfigParam(CONF_LOG_FILE,                      0,     0);
 	registerConfigParam(CONF_ERROR_FILE,                    0,     0);
 	registerConfigParam(CONF_PID_FILE,                      0,     0);

src/conf.h

@@ -27,6 +27,7 @@
 #define CONF_FOLLOW_INSIDE_SYMLINKS     "follow_inside_symlinks"
 #define CONF_FOLLOW_OUTSIDE_SYMLINKS    "follow_outside_symlinks"
 #define CONF_DB_FILE                    "db_file"
+#define CONF_STICKER_FILE "sticker_file"
 #define CONF_LOG_FILE                   "log_file"
 #define CONF_ERROR_FILE                 "error_file"
 #define CONF_PID_FILE                   "pid_file"

src/main.c

@@ -54,6 +54,10 @@
 #include "songvec.h"
 #include "tag_pool.h"
 
+#ifdef ENABLE_SQLITE
+#include "sticker.h"
+#endif
+
 #ifdef ENABLE_ARCHIVE
 #include "archive_list.h"
 #endif
@@ -235,6 +239,10 @@ int main(int argc, char *argv[])
 
 	openDB(&options, argv[0]);
 
+#ifdef ENABLE_SQLITE
+	sticker_global_init(config_get_path(CONF_STICKER_FILE));
+#endif
+
 	command_init();
 	initialize_decoder_and_player();
 	initAudioConfig();
@@ -278,6 +286,10 @@ int main(int argc, char *argv[])
 	g_debug("db_finish took %f seconds",
 		((float)(clock()-start))/CLOCKS_PER_SEC);
 
+#ifdef ENABLE_SQLITE
+	sticker_global_finish();
+#endif
+
 	notify_deinit(&main_notify);
 	event_pipe_deinit();
 

src/sticker.c

@@ -0,0 +1,361 @@
+/*
+ * Copyright (C) 2003-2009 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "sticker.h"
+
+#include <glib.h>
+#include <sqlite3.h>
+#include <assert.h>
+
+#undef G_LOG_DOMAIN
+#define G_LOG_DOMAIN "sticker"
+
+static const char sticker_sql_create[] =
+	"CREATE TABLE IF NOT EXISTS sticker("
+	"  type VARCHAR NOT NULL, "
+	"  uri VARCHAR NOT NULL, "
+	"  name VARCHAR NOT NULL, "
+	"  value VARCHAR NOT NULL"
+	");"
+	"CREATE UNIQUE INDEX IF NOT EXISTS"
+	" sticker_value ON sticker(type, uri, name);"
+	"";
+
+static const char sticker_sql_get[] =
+	"SELECT value FROM sticker WHERE type=? AND uri=? AND name=?";
+
+static const char sticker_sql_update[] =
+	"UPDATE sticker SET value=? WHERE type=? AND uri=? AND name=?";
+
+static const char sticker_sql_insert[] =
+	"INSERT INTO sticker(type,uri,name,value) VALUES(?, ?, ?, ?)";
+
+static const char sticker_sql_delete[] =
+	"DELETE FROM sticker WHERE type=? AND uri=?";
+
+static sqlite3 *sticker_db;
+static sqlite3_stmt *sticker_stmt_get, *sticker_stmt_update,
+	*sticker_stmt_insert, *sticker_stmt_delete;
+
+static sqlite3_stmt *
+sticker_prepare(const char *sql)
+{
+	int ret;
+	sqlite3_stmt *stmt;
+
+	ret = sqlite3_prepare_v2(sticker_db, sql, -1, &stmt, NULL);
+	if (ret != SQLITE_OK)
+		g_error("sqlite3_prepare_v2() failed: %s",
+			sqlite3_errmsg(sticker_db));
+
+	return stmt;
+}
+
+void
+sticker_global_init(const char *path)
+{
+	int ret;
+
+	if (path == NULL)
+		/* not configured */
+		return;
+
+	/* open/create the sqlite database */
+
+	ret = sqlite3_open(path, &sticker_db);
+	if (ret != SQLITE_OK)
+		g_error("Failed to open sqlite database '%s': %s",
+			path, sqlite3_errmsg(sticker_db));
+
+	/* create the table and index */
+
+	ret = sqlite3_exec(sticker_db, sticker_sql_create, NULL, NULL, NULL);
+	if (ret != SQLITE_OK)
+		g_error("Failed to create sticker table: %s",
+			sqlite3_errmsg(sticker_db));
+
+	/* prepare the statements we're going to use */
+
+	sticker_stmt_get = sticker_prepare(sticker_sql_get);
+	sticker_stmt_update = sticker_prepare(sticker_sql_update);
+	sticker_stmt_insert = sticker_prepare(sticker_sql_insert);
+	sticker_stmt_delete = sticker_prepare(sticker_sql_delete);
+
+	if (sticker_stmt_get == NULL || sticker_stmt_update == NULL ||
+	    sticker_stmt_insert == NULL || sticker_stmt_delete == NULL)
+		g_error("Failed to prepare sqlite statements");
+}
+
+void
+sticker_global_finish(void)
+{
+	if (sticker_db == NULL)
+		/* not configured */
+		return;
+
+	sqlite3_finalize(sticker_stmt_delete);
+	sqlite3_finalize(sticker_stmt_update);
+	sqlite3_finalize(sticker_stmt_insert);
+	sqlite3_close(sticker_db);
+}
+
+bool
+sticker_enabled(void)
+{
+	return sticker_db != NULL;
+}
+
+char *
+sticker_load_value(const char *type, const char *uri, const char *name)
+{
+	int ret;
+	char *value;
+
+	assert(sticker_enabled());
+	assert(type != NULL);
+	assert(uri != NULL);
+	assert(name != NULL);
+
+	if (*name == 0)
+		return NULL;
+
+	sqlite3_reset(sticker_stmt_get);
+
+	ret = sqlite3_bind_text(sticker_stmt_get, 1, type, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_bind_text(sticker_stmt_get, 2, uri, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_bind_text(sticker_stmt_get, 3, name, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	do {
+		ret = sqlite3_step(sticker_stmt_get);
+	} while (ret == SQLITE_BUSY);
+
+	if (ret == SQLITE_ROW) {
+		/* record found */
+		value = g_strdup((const char*)sqlite3_column_text(sticker_stmt_get, 0));
+	} else if (ret == SQLITE_DONE) {
+		/* no record found */
+		value = NULL;
+	} else {
+		/* error */
+		g_warning("sqlite3_step() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	sqlite3_reset(sticker_stmt_get);
+	sqlite3_clear_bindings(sticker_stmt_get);
+
+	return value;
+}
+
+static bool
+sticker_update_value(const char *type, const char *uri,
+		     const char *name, const char *value)
+{
+	int ret;
+
+	assert(type != NULL);
+	assert(uri != NULL);
+	assert(name != NULL);
+	assert(*name != 0);
+	assert(value != NULL);
+
+	assert(sticker_enabled());
+
+	sqlite3_reset(sticker_stmt_update);
+
+	ret = sqlite3_bind_text(sticker_stmt_update, 1, value, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_bind_text(sticker_stmt_update, 2, type, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_bind_text(sticker_stmt_update, 3, uri, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_bind_text(sticker_stmt_update, 4, name, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	do {
+		ret = sqlite3_step(sticker_stmt_update);
+	} while (ret == SQLITE_BUSY);
+
+	if (ret != SQLITE_DONE) {
+		g_warning("sqlite3_step() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_changes(sticker_db);
+
+	sqlite3_reset(sticker_stmt_update);
+	sqlite3_clear_bindings(sticker_stmt_update);
+
+	return ret > 0;
+}
+
+static bool
+sticker_insert_value(const char *type, const char *uri,
+		     const char *name, const char *value)
+{
+	int ret;
+
+	assert(type != NULL);
+	assert(uri != NULL);
+	assert(name != NULL);
+	assert(*name != 0);
+	assert(value != NULL);
+
+	assert(sticker_enabled());
+
+	sqlite3_reset(sticker_stmt_insert);
+
+	ret = sqlite3_bind_text(sticker_stmt_insert, 1, type, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_bind_text(sticker_stmt_insert, 2, uri, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_bind_text(sticker_stmt_insert, 3, name, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_bind_text(sticker_stmt_insert, 4, value, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	do {
+		ret = sqlite3_step(sticker_stmt_insert);
+	} while (ret == SQLITE_BUSY);
+
+	if (ret != SQLITE_DONE) {
+		g_warning("sqlite3_step() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	sqlite3_reset(sticker_stmt_insert);
+	sqlite3_clear_bindings(sticker_stmt_insert);
+
+	return true;
+}
+
+bool
+sticker_store_value(const char *type, const char *uri,
+		    const char *name, const char *value)
+{
+	assert(sticker_enabled());
+	assert(type != NULL);
+	assert(uri != NULL);
+	assert(name != NULL);
+	assert(value != NULL);
+
+	if (*name == 0)
+		return false;
+
+	return sticker_update_value(type, uri, name, value) ||
+		sticker_insert_value(type, uri, name, value);
+}
+
+bool
+sticker_delete(const char *type, const char *uri)
+{
+	int ret;
+
+	assert(sticker_enabled());
+	assert(type != NULL);
+	assert(uri != NULL);
+
+	sqlite3_reset(sticker_stmt_delete);
+
+	ret = sqlite3_bind_text(sticker_stmt_delete, 1, type, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	ret = sqlite3_bind_text(sticker_stmt_delete, 2, uri, -1, NULL);
+	if (ret != SQLITE_OK) {
+		g_warning("sqlite3_bind_text() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	do {
+		ret = sqlite3_step(sticker_stmt_delete);
+	} while (ret == SQLITE_BUSY);
+
+	if (ret != SQLITE_DONE) {
+		g_warning("sqlite3_step() failed: %s",
+			  sqlite3_errmsg(sticker_db));
+		return false;
+	}
+
+	sqlite3_reset(sticker_stmt_delete);
+	sqlite3_clear_bindings(sticker_stmt_delete);
+
+	return true;
+}

src/sticker.h

@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2003-2009 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/*
+ * This is the sticker database library.  It is the backend of all the
+ * sticker code in MPD.
+ *
+ * "Stickers" are pieces of information attached to existing MPD
+ * objects (e.g. song files, directories, albums).  Clients can create
+ * arbitrary name/value pairs.  MPD itself does not assume any special
+ * meaning in them.
+ *
+ * The goal is to allow clients to share additional (possibly dynamic)
+ * information about songs, which is neither stored on the client (not
+ * available to other clients), nor stored in the song files (MPD has
+ * no write access).
+ *
+ * Client developers should create a standard for common sticker
+ * names, to ensure interoperability.
+ *
+ * Examples: song ratings; statistics; deferred tag writes; lyrics;
+ * ...
+ *
+ */
+
+#ifndef STICKER_H
+#define STICKER_H
+
+#include <stdbool.h>
+
+/**
+ * Opens the sticker database (if path is not NULL).
+ */
+void
+sticker_global_init(const char *path);
+
+/**
+ * Close the sticker database.
+ */
+void
+sticker_global_finish(void);
+
+/**
+ * Returns true if the sticker database is configured and available.
+ */
+bool
+sticker_enabled(void);
+
+/**
+ * Returns one value from an object's sticker record.  The caller must
+ * free the return value with g_free().
+ */
+char *
+sticker_load_value(const char *type, const char *uri, const char *name);
+
+/**
+ * Sets a sticker value in the specified object.  Overwrites existing
+ * values.
+ */
+bool
+sticker_store_value(const char *type, const char *uri,
+		    const char *name, const char *value);
+
+/**
+ * Deletes a sticker from the database.  All sticker values of the
+ * specified object are deleted.
+ */
+bool
+sticker_delete(const char *type, const char *uri);
+
+#endif