path: root/src/directory.c

/* the Music Player Daemon (MPD)
 * Copyright (C) 2003-2007 by Warren Dukes (warren.dukes@gmail.com)
 * This project's homepage is: 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 "directory.h"

#include "conf.h"
#include "log.h"
#include "ls.h"
#include "path.h"
#include "playlist.h"
#include "stats.h"
#include "utils.h"
#include "client.h"
#include "dbUtils.h"
#include "song_print.h"
#include "song_save.h"
#include "main_notify.h"
#include "dirvec.h"
#include "condition.h"

#define DIRECTORY_DIR		"directory: "
#define DIRECTORY_MTIME		"mtime: " /* DEPRECATED, noop-read-only */
#define DIRECTORY_BEGIN		"begin: "
#define DIRECTORY_END		"end: "
#define DIRECTORY_INFO_BEGIN	"info_begin"
#define DIRECTORY_INFO_END	"info_end"
#define DIRECTORY_MPD_VERSION	"mpd_version: "
#define DIRECTORY_FS_CHARSET	"fs_charset: "

enum update_return {
	UPDATE_RETURN_ERROR = -1,
	UPDATE_RETURN_NOUPDATE = 0,
	UPDATE_RETURN_UPDATED = 1
};

enum update_progress {
	UPDATE_PROGRESS_IDLE = 0,
	UPDATE_PROGRESS_RUNNING = 1,
	UPDATE_PROGRESS_DONE = 2
} progress;

/* make this dynamic?, or maybe this is big enough... */
static char *update_paths[32];
static size_t update_paths_nr;

static Directory *music_root;

static time_t directory_dbModTime;

static pthread_t update_thr;

static const int update_task_id_max = 1 << 15;

static int update_task_id;

static Song *delete;

static struct condition delete_cond;

static enum update_return
addToDirectory(Directory * directory, const char *name);

static void freeDirectory(Directory * directory);

static enum update_return exploreDirectory(Directory * directory);

static enum update_return updateDirectory(Directory * directory);

static void deleteEmptyDirectoriesInDirectory(Directory * directory);

static void delete_song(Directory *dir, Song *del);

static enum update_return addSubDirectoryToDirectory(Directory * directory,
				      const char *name, struct stat *st);

static Directory *getDirectory(const char *name);

static enum update_return updatePath(const char *utf8path);

static void sortDirectory(Directory * directory);

static int inodeFoundInParent(Directory * parent, ino_t inode, dev_t device);

static int statDirectory(Directory * dir);

static char *getDbFile(void)
{
	ConfigParam *param = parseConfigFilePath(CONF_DB_FILE, 1);

	assert(param);
	assert(param->value);

	return param->value;
}

int isUpdatingDB(void)
{
	return (progress != UPDATE_PROGRESS_IDLE) ? update_task_id : 0;
}

static void * update_task(void *_path)
{
	enum update_return ret = UPDATE_RETURN_NOUPDATE;

	if (_path) {
		ret = updatePath((char *)_path);
		free(_path);
	} else {
		ret = updateDirectory(music_root);
	}

	if (ret == UPDATE_RETURN_UPDATED && writeDirectoryDB() < 0)
		ret = UPDATE_RETURN_ERROR;
	progress = UPDATE_PROGRESS_DONE;
	wakeup_main_task();
	return (void *)ret;
}

static void spawn_update_task(char *path)
{
	pthread_attr_t attr;

	assert(pthread_equal(pthread_self(), main_task));

	progress = UPDATE_PROGRESS_RUNNING;
	pthread_attr_init(&attr);
	if (pthread_create(&update_thr, &attr, update_task, path))
		FATAL("Failed to spawn update task: %s\n", strerror(errno));
	if (++update_task_id > update_task_id_max)
		update_task_id = 1;
	DEBUG("spawned thread for update job id %i\n", update_task_id);
}

void reap_update_task(void)
{
	enum update_return ret;

	assert(pthread_equal(pthread_self(), main_task));

	cond_enter(&delete_cond);
	if (delete) {
		char tmp[MPD_PATH_MAX];
		LOG("removing: %s\n", get_song_url(tmp, delete));
		deleteASongFromPlaylist(delete);
		delete = NULL;
		cond_signal_async(&delete_cond);
	}
	cond_leave(&delete_cond);

	if (progress != UPDATE_PROGRESS_DONE)
		return;
	if (pthread_join(update_thr, (void **)&ret))
		FATAL("error joining update thread: %s\n", strerror(errno));
	if (ret == UPDATE_RETURN_UPDATED)
		playlistVersionChange();

	if (update_paths_nr) {
		char *path = update_paths[0];
		memmove(&update_paths[0], &update_paths[1],
		        --update_paths_nr * sizeof(char *));
		spawn_update_task(path);
	} else {
		progress = UPDATE_PROGRESS_IDLE;
	}
}

int directory_update_init(char *path)
{
	assert(pthread_equal(pthread_self(), main_task));

	if (progress != UPDATE_PROGRESS_IDLE) {
		int next_task_id;

		if (!path)
			return -1;
		if (update_paths_nr == ARRAY_SIZE(update_paths))
			return -1;
		assert(update_paths_nr < ARRAY_SIZE(update_paths));
		update_paths[update_paths_nr++] = path;
		next_task_id = update_task_id + update_paths_nr;

		return next_task_id > update_task_id_max ?  1 : next_task_id;
	}
	spawn_update_task(path);
	return update_task_id;
}

static void directory_set_stat(Directory * dir, const struct stat *st)
{
	dir->inode = st->st_ino;
	dir->device = st->st_dev;
	dir->stat = 1;
}

static Directory *newDirectory(const char *dirname, Directory * parent)
{
	Directory *directory;

	directory = xcalloc(1, sizeof(Directory));

	if (dirname && strlen(dirname))
		directory->path = xstrdup(dirname);
	directory->parent = parent;

	return directory;
}

static void freeDirectory(Directory * directory)
{
	dirvec_destroy(&directory->children);
	songvec_destroy(&directory->songs);
	if (directory->path)
		free(directory->path);
	free(directory);
	/* this resets last dir returned */
	/*getDirectoryPath(NULL); */
}

static void delete_song(Directory *dir, Song *del)
{
	/* first, prevent traversers in main task from getting this */
	songvec_delete(&dir->songs, del);

	/* now take it out of the playlist (in the main_task) */
	cond_enter(&delete_cond);
	assert(!delete);
	delete = del;
	wakeup_main_task();
	do { cond_wait(&delete_cond); } while (delete);
	cond_leave(&delete_cond);

	/* finally, all possible references gone, free it */
	freeJustSong(del);
}

static void deleteEmptyDirectoriesInDirectory(Directory * directory)
{
	int i;
	struct dirvec *dv = &directory->children;

	for (i = dv->nr; --i >= 0; ) {
		deleteEmptyDirectoriesInDirectory(dv->base[i]);
		if (!dv->base[i]->children.nr && !dv->base[i]->songs.nr)
			dirvec_delete(dv, dv->base[i]);
	}
	if (!dv->nr)
		dirvec_destroy(dv);
}

static enum update_return
updateInDirectory(Directory * directory, const char *name)
{
	Song *song;
	struct stat st;

	if (myStat(name, &st))
		return UPDATE_RETURN_ERROR;

	if (S_ISREG(st.st_mode) && hasMusicSuffix(name, 0)) {
		const char *shortname = mpd_basename(name);

		if (!(song = songvec_find(&directory->songs, shortname))) {
			addToDirectory(directory, name);
			return UPDATE_RETURN_UPDATED;
		} else if (st.st_mtime != song->mtime) {
			LOG("updating %s\n", name);
			if (updateSongInfo(song) < 0)
				delete_song(directory, song);
			return UPDATE_RETURN_UPDATED;
		}
	} else if (S_ISDIR(st.st_mode)) {
		Directory *subdir = dirvec_find(&directory->children, name);
		if (subdir) {
			assert(directory == subdir->parent);
			directory_set_stat(subdir, &st);
			return updateDirectory(subdir);
		} else {
			return addSubDirectoryToDirectory(directory, name, &st);
		}
	}

	return UPDATE_RETURN_NOUPDATE;
}

/* we don't look at hidden files nor files with newlines in them */
static int skip_path(const char *path)
{
	return (path[0] == '.' || strchr(path, '\n')) ? 1 : 0;
}

struct delete_data {
	char *tmp;
	Directory *dir;
	enum update_return ret;
};

/* passed to songvec_for_each */
static int delete_song_if_removed(Song *song, void *_data)
{
	struct delete_data *data = _data;

	data->tmp = get_song_url(data->tmp, song);
	assert(data->tmp);

	if (!isFile(data->tmp, NULL)) {
		delete_song(data->dir, song);
		data->ret = UPDATE_RETURN_UPDATED;
	}
	return 0;
}

static enum update_return
removeDeletedFromDirectory(char *path_max_tmp, Directory * directory)
{
	enum update_return ret = UPDATE_RETURN_NOUPDATE;
	int i;
	struct dirvec *dv = &directory->children;
	struct delete_data data;

	for (i = dv->nr; --i >= 0; ) {
		if (isDir(dv->base[i]->path))
			continue;
		LOG("removing directory: %s\n", dv->base[i]->path);
		dirvec_delete(dv, dv->base[i]);
		ret = UPDATE_RETURN_UPDATED;
	}

	data.dir = directory;
	data.tmp = path_max_tmp;
	data.ret = ret;
	songvec_for_each(&directory->songs, delete_song_if_removed, &data);

	return data.ret;
}

static Directory *addDirectoryPathToDB(const char *utf8path)
{
	char path_max_tmp[MPD_PATH_MAX];
	char *parent;
	Directory *parentDirectory;
	Directory *directory;
	Song *conflicting;

	parent = parent_path(path_max_tmp, utf8path);

	if (strlen(parent) == 0)
		parentDirectory = music_root;
	else
		parentDirectory = addDirectoryPathToDB(parent);

	if (!parentDirectory)
		return NULL;

	if ((directory = dirvec_find(&parentDirectory->children, utf8path))) {
		assert(parentDirectory == directory->parent);
	} else {
		struct stat st;
		if (myStat(utf8path, &st) < 0 ||
		    inodeFoundInParent(parentDirectory, st.st_ino, st.st_dev))
			return NULL;
		else {
			directory = newDirectory(utf8path, parentDirectory);
			dirvec_add(&parentDirectory->children, directory);
		}
	}

	/* if we're adding directory paths, make sure to delete filenames
	   with potentially the same name */
	conflicting = songvec_find(&parentDirectory->songs,
	                           mpd_basename(directory->path));
	if (conflicting)
		delete_song(parentDirectory, conflicting);

	return directory;
}

static Directory *addParentPathToDB(const char *utf8path)
{
	char *parent;
	char path_max_tmp[MPD_PATH_MAX];
	Directory *parentDirectory;

	parent = parent_path(path_max_tmp, utf8path);

	if (strlen(parent) == 0)
		parentDirectory = music_root;
	else
		parentDirectory = addDirectoryPathToDB(parent);

	if (!parentDirectory)
		return NULL;

	return (Directory *) parentDirectory;
}

static enum update_return updatePath(const char *utf8path)
{
	Directory *directory;
	Directory *parentDirectory;
	Song *song;
	char *path = sanitizePathDup(utf8path);
	time_t mtime;
	enum update_return ret = UPDATE_RETURN_NOUPDATE;
	char path_max_tmp[MPD_PATH_MAX];

	if (NULL == path)
		return UPDATE_RETURN_ERROR;

	/* if path is in the DB try to update it, or else delete it */
	if ((directory = getDirectory(path))) {
		parentDirectory = directory->parent;

		/* if this update directory is successfull, we are done */
		ret = updateDirectory(directory);
		if (ret != UPDATE_RETURN_ERROR) {
			free(path);
			sortDirectory(directory);
			return ret;
		}
		/* we don't want to delete the root directory */
		else if (directory == music_root) {
			free(path);
			return UPDATE_RETURN_NOUPDATE;
		}
		/* if updateDirectory fails, means we should delete it */
		else {
			LOG("removing directory: %s\n", path);
			dirvec_delete(&parentDirectory->children, directory);
			ret = UPDATE_RETURN_UPDATED;
			/* don't return, path maybe a song now */
		}
	} else if ((song = getSongFromDB(path))) {
		parentDirectory = song->parentDir;
		if (!parentDirectory->stat
		    && statDirectory(parentDirectory) < 0) {
			free(path);
			return UPDATE_RETURN_NOUPDATE;
		}
		/* if this song update is successful, we are done */
		else if (!inodeFoundInParent(parentDirectory->parent,
						 parentDirectory->inode,
						 parentDirectory->device) &&
			 isMusic(get_song_url(path_max_tmp, song), &mtime, 0)) {
			free(path);
			if (song->mtime == mtime)
				return UPDATE_RETURN_NOUPDATE;
			else if (updateSongInfo(song) == 0)
				return UPDATE_RETURN_UPDATED;
			else {
				delete_song(parentDirectory, song);
				return UPDATE_RETURN_UPDATED;
			}
		}
		/* if updateDirectory fails, means we should delete it */
		else {
			delete_song(parentDirectory, song);
			ret = UPDATE_RETURN_UPDATED;
			/* don't return, path maybe a directory now */
		}
	}

	/* path not found in the db, see if it actually exists on the fs.
	 * Also, if by chance a directory was replaced by a file of the same
	 * name or vice versa, we need to add it to the db
	 */
	if (isDir(path) || isMusic(path, NULL, 0)) {
		parentDirectory = addParentPathToDB(path);
		if (!parentDirectory || (!parentDirectory->stat &&
					 statDirectory(parentDirectory) < 0)) {
		} else if (0 == inodeFoundInParent(parentDirectory->parent,
						   parentDirectory->inode,
						   parentDirectory->device)
			   && addToDirectory(parentDirectory, path)
			   == UPDATE_RETURN_UPDATED) {
			ret = UPDATE_RETURN_UPDATED;
		}
	}

	free(path);

	return ret;
}

static const char *opendir_path(char *path_max_tmp, const char *dirname)
{
	if (*dirname != '\0')
		return rmp2amp_r(path_max_tmp,
		                 utf8_to_fs_charset(path_max_tmp, dirname));
	return musicDir;
}

static enum update_return updateDirectory(Directory * directory)
{
	DIR *dir;
	const char *dirname = getDirectoryPath(directory);
	struct dirent *ent;
	char path_max_tmp[MPD_PATH_MAX];
	enum update_return ret = UPDATE_RETURN_NOUPDATE;

	if (!directory->stat && statDirectory(directory) < 0)
		return UPDATE_RETURN_ERROR;
	else if (inodeFoundInParent(directory->parent,
				    directory->inode,
				    directory->device))
		return UPDATE_RETURN_ERROR;

	dir = opendir(opendir_path(path_max_tmp, dirname));
	if (!dir)
		return UPDATE_RETURN_ERROR;

	if (removeDeletedFromDirectory(path_max_tmp, directory) > 0)
		ret = UPDATE_RETURN_UPDATED;

	while ((ent = readdir(dir))) {
		char *utf8;
		if (skip_path(ent->d_name))
			continue;

		utf8 = fs_charset_to_utf8(path_max_tmp, ent->d_name);
		if (!utf8)
			continue;

		if (directory->path)
			utf8 = pfx_dir(path_max_tmp, utf8, strlen(utf8),
			               dirname, strlen(dirname));
		if (updateInDirectory(directory, path_max_tmp) > 0)
			ret = UPDATE_RETURN_UPDATED;
	}

	closedir(dir);

	return ret;
}

static enum update_return exploreDirectory(Directory * directory)
{
	DIR *dir;
	const char *dirname = getDirectoryPath(directory);
	struct dirent *ent;
	char path_max_tmp[MPD_PATH_MAX];
	enum update_return ret = UPDATE_RETURN_NOUPDATE;

	DEBUG("explore: attempting to opendir: %s\n", dirname);

	dir = opendir(opendir_path(path_max_tmp, dirname));
	if (!dir)
		return UPDATE_RETURN_ERROR;

	DEBUG("explore: %s\n", dirname);

	while ((ent = readdir(dir))) {
		char *utf8;
		if (skip_path(ent->d_name))
			continue;

		utf8 = fs_charset_to_utf8(path_max_tmp, ent->d_name);
		if (!utf8)
			continue;

		DEBUG("explore: found: %s (%s)\n", ent->d_name, utf8);

		if (directory->path)
			utf8 = pfx_dir(path_max_tmp, utf8, strlen(utf8),
			               dirname, strlen(dirname));
		if (addToDirectory(directory, path_max_tmp) ==
		    UPDATE_RETURN_UPDATED)
			ret = UPDATE_RETURN_UPDATED;
	}

	closedir(dir);

	return ret;
}

static int statDirectory(Directory * dir)
{
	struct stat st;

	if (myStat(getDirectoryPath(dir), &st) < 0)
		return -1;

	directory_set_stat(dir, &st);

	return 0;
}

static int inodeFoundInParent(Directory * parent, ino_t inode, dev_t device)
{
	while (parent) {
		if (!parent->stat && statDirectory(parent) < 0)
			return -1;
		if (parent->inode == inode && parent->device == device) {
			DEBUG("recursive directory found\n");
			return 1;
		}
		parent = parent->parent;
	}

	return 0;
}

static enum update_return addSubDirectoryToDirectory(Directory * directory,
				      const char *name, struct stat *st)
{
	Directory *subDirectory;

	if (inodeFoundInParent(directory, st->st_ino, st->st_dev))
		return UPDATE_RETURN_NOUPDATE;

	subDirectory = newDirectory(name, directory);
	directory_set_stat(subDirectory, st);

	if (exploreDirectory(subDirectory) != UPDATE_RETURN_UPDATED) {
		freeDirectory(subDirectory);
		return UPDATE_RETURN_NOUPDATE;
	}

	dirvec_add(&directory->children, subDirectory);

	return UPDATE_RETURN_UPDATED;
}

static enum update_return
addToDirectory(Directory * directory, const char *name)
{
	struct stat st;

	if (myStat(name, &st)) {
		DEBUG("failed to stat %s: %s\n", name, strerror(errno));
		return UPDATE_RETURN_ERROR;
	}

	if (S_ISREG(st.st_mode) &&
	    hasMusicSuffix(name, 0) && isMusic(name, NULL, 0)) {
		Song *song;
		const char *shortname = mpd_basename(name);

		if (!(song = newSong(shortname, directory)))
			return -1;
		songvec_add(&directory->songs, song);
		LOG("added %s\n", name);
		return UPDATE_RETURN_UPDATED;
	} else if (S_ISDIR(st.st_mode)) {
		return addSubDirectoryToDirectory(directory, name, &st);
	}

	DEBUG("addToDirectory: %s is not a directory or music\n", name);

	return UPDATE_RETURN_ERROR;
}

void directory_finish(void)
{
	freeDirectory(music_root);
}

int isRootDirectory(const char *name)
{
	return (!name || name[0] == '\0' || !strcmp(name, "/"));
}

static Directory *getSubDirectory(Directory * directory, const char *name)
{
	Directory *cur = directory;
	Directory *found = NULL;
	char *duplicated;
	char *locate;

	if (isRootDirectory(name))
		return directory;

	duplicated = xstrdup(name);
	locate = strchr(duplicated, '/');
	while (1) {
		if (locate)
			*locate = '\0';
		if (!(found = dirvec_find(&cur->children, duplicated)))
			break;
		assert(cur == found->parent);
		cur = found;
		if (!locate)
			break;
		*locate = '/';
		locate = strchr(locate + 1, '/');
	}

	free(duplicated);

	return found;
}

static Directory *getDirectory(const char *name)
{
	return getSubDirectory(music_root, name);
}

static int printDirectoryList(struct client *client, struct dirvec *dv)
{
	size_t i;

	for (i = 0; i < dv->nr; ++i) {
		client_printf(client, DIRECTORY_DIR "%s\n",
			      getDirectoryPath(dv->base[i]));
	}

	return 0;
}

int printDirectoryInfo(struct client *client, const char *name)
{
	Directory *directory;

	if ((directory = getDirectory(name)) == NULL)
		return -1;

	printDirectoryList(client, &directory->children);
	songvec_print(client, &directory->songs);

	return 0;
}

/* TODO error checking */
static int writeDirectoryInfo(FILE * fp, Directory * directory)
{
	struct dirvec *children = &directory->children;
	size_t i;
	int retv;

	if (directory->path) {
		retv = fprintf(fp, "%s%s\n", DIRECTORY_BEGIN,
			       getDirectoryPath(directory));
		if (retv < 0)
			return -1;
	}

	for (i = 0; i < children->nr; ++i) {
		Directory *cur = children->base[i];
		const char *base = mpd_basename(cur->path);

		retv = fprintf(fp, DIRECTORY_DIR "%s\n", base);
		if (retv < 0)
			return -1;
		if (writeDirectoryInfo(fp, cur) < 0)
			return -1;
	}

	songvec_save(fp, &directory->songs);

	if (directory->path &&
	    fprintf(fp, DIRECTORY_END "%s\n",
		    getDirectoryPath(directory)) < 0)
		return -1;
	return 0;
}

static void readDirectoryInfo(FILE * fp, Directory * directory)
{
	char buffer[MPD_PATH_MAX * 2];
	int bufferSize = MPD_PATH_MAX * 2;
	char key[MPD_PATH_MAX * 2];
	char *name;

	while (myFgets(buffer, bufferSize, fp)
	       && prefixcmp(buffer, DIRECTORY_END)) {
		if (!prefixcmp(buffer, DIRECTORY_DIR)) {
			Directory *subdir;

			strcpy(key, &(buffer[strlen(DIRECTORY_DIR)]));
			if (!myFgets(buffer, bufferSize, fp))
				FATAL("Error reading db, fgets\n");
			/* for compatibility with db's prior to 0.11 */
			if (!prefixcmp(buffer, DIRECTORY_MTIME)) {
				if (!myFgets(buffer, bufferSize, fp))
					FATAL("Error reading db, fgets\n");
			}
			if (prefixcmp(buffer, DIRECTORY_BEGIN))
				FATAL("Error reading db at line: %s\n", buffer);
			name = &(buffer[strlen(DIRECTORY_BEGIN)]);
			if ((subdir = getDirectory(name))) {
				assert(subdir->parent == directory);
			} else {
				subdir = newDirectory(name, directory);
				dirvec_add(&directory->children, subdir);
			}
			readDirectoryInfo(fp, subdir);
		} else if (!prefixcmp(buffer, SONG_BEGIN)) {
			readSongInfoIntoList(fp, &directory->songs, directory);
		} else {
			FATAL("Unknown line in db: %s\n", buffer);
		}
	}
}

static void sortDirectory(Directory * directory)
{
	int i;
	struct dirvec *dv = &directory->children;

	dirvec_sort(dv);
	songvec_sort(&directory->songs);

	for (i = dv->nr; --i >= 0; )
		sortDirectory(dv->base[i]);
}

int checkDirectoryDB(void)
{
	struct stat st;
	char *dbFile = getDbFile();

	/* Check if the file exists */
	if (access(dbFile, F_OK)) {
		/* If the file doesn't exist, we can't check if we can write
		 * it, so we are going to try to get the directory path, and
		 * see if we can write a file in that */
		char dirPath[MPD_PATH_MAX];
		parent_path(dirPath, dbFile);
		if (*dirPath == '\0')
			strcpy(dirPath, "/");

		/* Check that the parent part of the path is a directory */
		if (stat(dirPath, &st) < 0) {
			ERROR("Couldn't stat parent directory of db file "
			      "\"%s\": %s\n", dbFile, strerror(errno));
			return -1;
		}

		if (!S_ISDIR(st.st_mode)) {
			ERROR("Couldn't create db file \"%s\" because the "
			      "parent path is not a directory\n", dbFile);
			return -1;
		}

		/* Check if we can write to the directory */
		if (access(dirPath, R_OK | W_OK)) {
			ERROR("Can't create db file in \"%s\": %s\n", dirPath,
			      strerror(errno));
			return -1;
		}

		return 0;
	}

	/* Path exists, now check if it's a regular file */
	if (stat(dbFile, &st) < 0) {
		ERROR("Couldn't stat db file \"%s\": %s\n", dbFile,
		      strerror(errno));
		return -1;
	}

	if (!S_ISREG(st.st_mode)) {
		ERROR("db file \"%s\" is not a regular file\n", dbFile);
		return -1;
	}

	/* And check that we can write to it */
	if (access(dbFile, R_OK | W_OK)) {
		ERROR("Can't open db file \"%s\" for reading/writing: %s\n",
		      dbFile, strerror(errno));
		return -1;
	}

	return 0;
}

int writeDirectoryDB(void)
{
	FILE *fp;
	char *dbFile = getDbFile();
	struct stat st;

	DEBUG("removing empty directories from DB\n");
	deleteEmptyDirectoriesInDirectory(music_root);

	DEBUG("sorting DB\n");

	sortDirectory(music_root);

	DEBUG("writing DB\n");

	fp = fopen(dbFile, "w");
	if (!fp) {
		ERROR("unable to write to db file \"%s\": %s\n",
		      dbFile, strerror(errno));
		return -1;
	}

	/* block signals when writing the db so we don't get a corrupted db */
	fprintf(fp, "%s\n", DIRECTORY_INFO_BEGIN);
	fprintf(fp, "%s%s\n", DIRECTORY_MPD_VERSION, VERSION);
	fprintf(fp, "%s%s\n", DIRECTORY_FS_CHARSET, getFsCharset());
	fprintf(fp, "%s\n", DIRECTORY_INFO_END);

	if (writeDirectoryInfo(fp, music_root) < 0) {
		ERROR("Failed to write to database file: %s\n",
		      strerror(errno));
		while (fclose(fp) && errno == EINTR);
		return -1;
	}

	while (fclose(fp) && errno == EINTR);

	if (stat(dbFile, &st) == 0)
		directory_dbModTime = st.st_mtime;

	return 0;
}

int readDirectoryDB(void)
{
	FILE *fp = NULL;
	char *dbFile = getDbFile();
	struct stat st;

	if (!music_root)
		music_root = newDirectory(NULL, NULL);
	while (!(fp = fopen(dbFile, "r")) && errno == EINTR) ;
	if (fp == NULL) {
		ERROR("unable to open db file \"%s\": %s\n",
		      dbFile, strerror(errno));
		return -1;
	}

	/* get initial info */
	{
		char buffer[100];
		int bufferSize = 100;
		int foundFsCharset = 0;
		int foundVersion = 0;

		if (!myFgets(buffer, bufferSize, fp))
			FATAL("Error reading db, fgets\n");
		if (0 == strcmp(DIRECTORY_INFO_BEGIN, buffer)) {
			while (myFgets(buffer, bufferSize, fp) &&
			       0 != strcmp(DIRECTORY_INFO_END, buffer)) {
				if (!prefixcmp(buffer, DIRECTORY_MPD_VERSION))
				{
					if (foundVersion)
						FATAL("already found version in db\n");
					foundVersion = 1;
				} else if (!prefixcmp(buffer,
				                      DIRECTORY_FS_CHARSET)) {
					char *fsCharset;
					char *tempCharset;

					if (foundFsCharset)
						FATAL("already found fs charset in db\n");

					foundFsCharset = 1;

					fsCharset = &(buffer[strlen(DIRECTORY_FS_CHARSET)]);
					if ((tempCharset = getConfigParamValue(CONF_FS_CHARSET))
					    && strcmp(fsCharset, tempCharset)) {
						WARNING("Using \"%s\" for the "
							"filesystem charset "
							"instead of \"%s\"\n",
							fsCharset, tempCharset);
						WARNING("maybe you need to "
							"recreate the db?\n");
						setFsCharset(fsCharset);
					}
				} else {
					FATAL("directory: unknown line in db info: %s\n",
					     buffer);
				}
			}
		} else {
			ERROR("db info not found in db file\n");
			ERROR("you should recreate the db using --create-db\n");
			while (fclose(fp) && errno == EINTR) ;
			return -1;
		}
	}

	DEBUG("reading DB\n");

	readDirectoryInfo(fp, music_root);
	while (fclose(fp) && errno == EINTR) ;

	stats.numberOfSongs = countSongsIn(NULL);
	stats.dbPlayTime = sumSongTimesIn(NULL);

	if (stat(dbFile, &st) == 0)
		directory_dbModTime = st.st_mtime;

	return 0;
}

static int traverseAllInSubDirectory(Directory * directory,
				     int (*forEachSong) (Song *, void *),
				     int (*forEachDir) (Directory *, void *),
				     void *data)
{
	struct dirvec *dv = &directory->children;
	int err = 0;
	size_t j;

	if (forEachDir && (err = forEachDir(directory, data)) < 0)
		return err;

	if (forEachSong) {
		err = songvec_for_each(&directory->songs, forEachSong, data);
		if (err < 0)
			return err;
	}

	for (j = 0; err >= 0 && j < dv->nr; ++j)
		err = traverseAllInSubDirectory(dv->base[j], forEachSong,
						forEachDir, data);

	return err;
}

int traverseAllIn(const char *name,
		  int (*forEachSong) (Song *, void *),
		  int (*forEachDir) (Directory *, void *), void *data)
{
	Directory *directory;

	if ((directory = getDirectory(name)) == NULL) {
		Song *song;
		if ((song = getSongFromDB(name)) && forEachSong) {
			return forEachSong(song, data);
		}
		return -1;
	}

	return traverseAllInSubDirectory(directory, forEachSong, forEachDir,
					 data);
}

void directory_init(void)
{
	music_root = newDirectory(NULL, NULL);
	exploreDirectory(music_root);
	stats.numberOfSongs = countSongsIn(NULL);
	stats.dbPlayTime = sumSongTimesIn(NULL);
}

Song *getSongFromDB(const char *file)
{
	Song *song = NULL;
	Directory *directory;
	char *dir = NULL;
	char *duplicated = xstrdup(file);
	char *shortname = strrchr(duplicated, '/');

	DEBUG("get song: %s\n", file);

	if (!shortname) {
		shortname = duplicated;
	} else {
		*shortname = '\0';
		++shortname;
		dir = duplicated;
	}

	if (!(directory = getDirectory(dir)))
		goto out;
	if (!(song = songvec_find(&directory->songs, shortname)))
		goto out;
	assert(song->parentDir == directory);

out:
	free(duplicated);
	return song;
}

time_t getDbModTime(void)
{
	return directory_dbModTime;
}