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 "command.h"
#include "conf.h"
#include "log.h"
#include "ls.h"
#include "path.h"
#include "playlist.h"
#include "stats.h"
#include "utils.h"
#include "ack.h"
#include "myfprintf.h"
#include "dbUtils.h"
#include "main_notify.h"
#include "dirvec.h"

#define DIRECTORY_DIR		"directory: "
#define DIRECTORY_MTIME		"mtime: "
#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;

static Directory *mp3rootDirectory;

static time_t directory_dbModTime;

static pthread_t update_thr;

static int directory_updateJobId;

static int addToDirectory(Directory * directory,
			  const char *shortname, 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 removeSongFromDirectory(Directory * directory,
				    const char *shortname);

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

static Directory *getDirectoryDetails(const char *name,
				      const char **shortname);

static Directory *getDirectory(const char *name);

static Song *getSongDetails(const char *file, const char **shortnameRet,
			    Directory ** directoryRet);

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) ? directory_updateJobId : 0;
}

void reap_update_task(void)
{
	enum update_return ret;

	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();
	progress = UPDATE_PROGRESS_IDLE;
}

static void * update_task(void *arg)
{
	List *path_list = (List *)arg;
	enum update_return ret = UPDATE_RETURN_NOUPDATE;

	if (path_list) {
		ListNode *node = path_list->firstNode;

		while (node) {
			switch (updatePath(node->key)) {
			case UPDATE_RETURN_ERROR:
				ret = UPDATE_RETURN_ERROR;
				goto out;
			case UPDATE_RETURN_NOUPDATE:
				break;
			case UPDATE_RETURN_UPDATED:
				ret = UPDATE_RETURN_UPDATED;
			}
			node = node->nextNode;
		}
		freeList(path_list);
	} else {
		ret = updateDirectory(mp3rootDirectory);
	}

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

int updateInit(int fd, List * path_list)
{
	pthread_attr_t attr;

	if (progress != UPDATE_PROGRESS_IDLE) {
		commandError(fd, ACK_ERROR_UPDATE_ALREADY, "already updating");
		return -1;
	}
	progress = UPDATE_PROGRESS_RUNNING;

	pthread_attr_init(&attr);
	if (pthread_create(&update_thr, &attr, update_task, path_list))
		FATAL("Failed to spawn update task: %s\n", strerror(errno));
	directory_updateJobId++;
	if (directory_updateJobId > 1 << 15)
		directory_updateJobId = 1;
	DEBUG("updateInit: spawned update thread for update job id %i\n",
	      (int)directory_updateJobId);
	fdprintf(fd, "updating_db: %i\n", (int)directory_updateJobId);

	return 0;
}

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 removeSongFromDirectory(Directory * directory, const char *shortname)
{
	Song *song = songvec_find(&directory->songs, shortname);

	if (song) {
		char path_max_tmp[MPD_PATH_MAX]; /* wasteful */
		LOG("removing: %s\n", get_song_url(path_max_tmp, song));
		songvec_delete(&directory->songs, song);
		freeSong(song); /* FIXME racy */
	}
}

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

static enum update_return
removeDeletedFromDirectory(char *path_max_tmp, Directory * directory)
{
	const char *dirname = (directory && directory->path) ?
	    directory->path : NULL;
	enum update_return ret = UPDATE_RETURN_NOUPDATE;
	int i;
	struct songvec *sv = &directory->songs;
	struct dirvec *dv = &directory->children;

	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;
	}

	for (i = sv->nr; --i >= 0; ) { /* cleaner deletes if we go backwards */
		Song *song = sv->base[i];
		if (!song || !song->url)
			continue; /* does this happen?, perhaps assert() */

		if (dirname)
			sprintf(path_max_tmp, "%s/%s", dirname, song->url);
		else
			strcpy(path_max_tmp, song->url);

		if (!isFile(path_max_tmp, NULL)) {
			removeSongFromDirectory(directory, song->url);
			ret = UPDATE_RETURN_UPDATED;
		}
	}

	return ret;
}

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

	parent = parent_path(path_max_tmp, utf8path);

	if (strlen(parent) == 0)
		parentDirectory = (void *)mp3rootDirectory;
	else
		parentDirectory = addDirectoryPathToDB(parent, shortname);

	if (!parentDirectory)
		return NULL;

	*shortname = utf8path + strlen(parent);
	while (*(*shortname) && *(*shortname) == '/')
		(*shortname)++;

	if (!(directory = dirvec_find(&parentDirectory->children, utf8path))) {
		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 */
	removeSongFromDirectory(parentDirectory, *shortname);

	return directory;
}

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

	parent = parent_path(path_max_tmp, utf8path);

	if (strlen(parent) == 0)
		parentDirectory = (void *)mp3rootDirectory;
	else
		parentDirectory = addDirectoryPathToDB(parent, shortname);

	if (!parentDirectory)
		return NULL;

	*shortname = utf8path + strlen(parent);
	while (*(*shortname) && *(*shortname) == '/')
		(*shortname)++;

	return (Directory *) parentDirectory;
}

static enum update_return updatePath(const char *utf8path)
{
	Directory *directory;
	Directory *parentDirectory;
	Song *song;
	const char *shortname;
	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 = getDirectoryDetails(path, &shortname))) {
		parentDirectory = directory->parent;

		/* if this update directory is successfull, we are done */
		if ((ret = updateDirectory(directory)) >= 0) {
			free(path);
			sortDirectory(directory);
			return ret;
		}
		/* we don't want to delete the root directory */
		else if (directory == mp3rootDirectory) {
			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 = getSongDetails(path, &shortname, &parentDirectory))) {
		if (!parentDirectory->stat
		    && statDirectory(parentDirectory) < 0) {
			free(path);
			return UPDATE_RETURN_NOUPDATE;
		}
		/* if this song update is successfull, we are done */
		else if (0 == inodeFoundInParent(parentDirectory->parent,
						 parentDirectory->inode,
						 parentDirectory->device)
			 && song &&
			 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 {
				removeSongFromDirectory(parentDirectory,
							shortname);
				return UPDATE_RETURN_UPDATED;
			}
		}
		/* if updateDirectory fails, means we should delete it */
		else {
			removeSongFromDirectory(parentDirectory, shortname);
			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, &shortname);
		if (!parentDirectory || (!parentDirectory->stat &&
					 statDirectory(parentDirectory) < 0)) {
		} else if (0 == inodeFoundInParent(parentDirectory->parent,
						   parentDirectory->inode,
						   parentDirectory->device)
			   && addToDirectory(parentDirectory, shortname, path)
			   > 0) {
			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, utf8, 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, utf8, path_max_tmp) > 0)
			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 *shortname,
				      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) < 1) {
		freeDirectory(subDirectory);
		return UPDATE_RETURN_NOUPDATE;
	}

	dirvec_add(&directory->children, subDirectory);

	return UPDATE_RETURN_UPDATED;
}

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

	if (myStat(name, &st)) {
		DEBUG("failed to stat %s: %s\n", name, strerror(errno));
		return -1;
	}

	if (S_ISREG(st.st_mode) &&
	    hasMusicSuffix(name, 0) && isMusic(name, NULL, 0)) {
		Song *song = newSong(shortname, SONG_TYPE_FILE, directory);
		if (!song)
			return -1;
		songvec_add(&directory->songs, song);
		LOG("added %s\n", name);
		return 1;
	} else if (S_ISDIR(st.st_mode)) {
		return addSubDirectoryToDirectory(directory, shortname, name,
						  &st);
	}

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

	return -1;
}

void closeMp3Directory(void)
{
	freeDirectory(mp3rootDirectory);
}

int isRootDirectory(const char *name)
{
	if (name == NULL || name[0] == '\0' || strcmp(name, "/") == 0) {
		return 1;
	}
	return 0;
}

static Directory *getSubDirectory(Directory * directory, const char *name,
				  const char **shortname)
{
	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;
		cur = found;
		if (!locate)
			break;
		*locate = '/';
		locate = strchr(locate + 1, '/');
	}

	free(duplicated);

	if (found && (!(*shortname = strrchr(found->path, '/'))))
		*shortname = found->path;

	return found;
}

static Directory *getDirectoryDetails(const char *name, const char **shortname)
{
	*shortname = NULL;

	return getSubDirectory(mp3rootDirectory, name, shortname);
}

static Directory *getDirectory(const char *name)
{
	const char *shortname;

	return getSubDirectory(mp3rootDirectory, name, &shortname);
}

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

	for (i = 0; i < dv->nr; ++i) {
		if (fdprintf(fd, DIRECTORY_DIR "%s\n",
		             getDirectoryPath(dv->base[i])) < 0)
			return -1;
	}

	return 0;
}

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

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

	printDirectoryList(fd, &directory->children);
	songvec_write(&directory->songs, fd, 0);

	return 0;
}

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

	if (directory->path) {
		retv = fdprintf(fd, DIRECTORY_BEGIN "%s\n",
			  getDirectoryPath(directory));
		if (retv < 0) {
			ERROR("Failed to write data to database file: %s\n",strerror(errno));
			return;
		}
	}

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

		base = base ? base + 1 : cur->path;
		assert(*base);

		retv = fdprintf(fd, DIRECTORY_DIR "%s\n", base);
		if (retv < 0) {
			ERROR("Failed to write data to database file: %s\n",
			      strerror(errno));
			return;
		}
		writeDirectoryInfo(fd, cur);
	}
	songvec_write(&directory->songs, fd, 1);

	if (directory->path) {
		retv = fdprintf(fd, DIRECTORY_END "%s\n",
			  getDirectoryPath(directory));
		if (retv < 0) {
			ERROR("Failed to write data to database file: %s\n",strerror(errno));
			return;
		}
	}
}

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];
	Directory *subDirectory;
	char *name;

	while (myFgets(buffer, bufferSize, fp)
	       && prefixcmp(buffer, DIRECTORY_END)) {
		if (!prefixcmp(buffer, DIRECTORY_DIR)) {
			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)]);
			subDirectory = newDirectory(name, directory);
			dirvec_add(&directory->children, subDirectory);
			readDirectoryInfo(fp, subDirectory);
		} else if (!prefixcmp(buffer, SONG_BEGIN)) {
			readSongInfoIntoList(fp, 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)
{
	int fd;
	char *dbFile = getDbFile();
	struct stat st;

	DEBUG("removing empty directories from DB\n");
	deleteEmptyDirectoriesInDirectory(mp3rootDirectory);

	DEBUG("sorting DB\n");

	sortDirectory(mp3rootDirectory);

	DEBUG("writing DB\n");

	fd = open(dbFile, O_WRONLY|O_TRUNC|O_CREAT, 0666);
	if (fd < 0) {
		ERROR("unable to write to db file \"%s\": %s\n",
		      dbFile, strerror(errno));
		return -1;
	}

	/*
	 * TODO: block signals when writing the db so we don't get a corrupted
	 * db (or unexpected failures).  fdprintf() needs better error handling
	 */
	fdprintf(fd,
	         DIRECTORY_INFO_BEGIN "\n"
	         DIRECTORY_MPD_VERSION VERSION "\n"
	         DIRECTORY_FS_CHARSET "%s\n"
	         DIRECTORY_INFO_END "\n", getFsCharset());

	writeDirectoryInfo(fd, mp3rootDirectory);

	xclose(fd);

	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 (!mp3rootDirectory)
		mp3rootDirectory = 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, mp3rootDirectory);
	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 errFlag = 0;
	size_t j;

	if (forEachDir) {
		errFlag = forEachDir(directory, data);
		if (errFlag)
			return errFlag;
	}

	if (forEachSong) {
		int i;
		struct songvec *sv = &directory->songs;
		Song **sp = sv->base;

		for (i = sv->nr; --i >= 0; ) {
			Song *song = *sp++;
			if ((errFlag = forEachSong(song, data)))
				return errFlag;
		}
	}

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

	return errFlag;
}

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 initMp3Directory(void)
{
	mp3rootDirectory = newDirectory(NULL, NULL);
	exploreDirectory(mp3rootDirectory);
	stats.numberOfSongs = countSongsIn(NULL);
	stats.dbPlayTime = sumSongTimesIn(NULL);
}

static Song *getSongDetails(const char *file, const char **shortnameRet,
			    Directory ** directoryRet)
{
	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;

	if (shortnameRet)
		*shortnameRet = song->url;
	if (directoryRet)
		*directoryRet = directory;
out:
	free(duplicated);
	return song;
}

Song *getSongFromDB(const char *file)
{
	return getSongDetails(file, NULL, NULL);
}

time_t getDbModTime(void)
{
	return directory_dbModTime;
}