In updateInDirectory(), add new directories immediately and
delete them when they turn out to be empty. This simplifies the code
and allows us to eliminate addSubDirectoryToDirectory().
If the user requests database update during startup, call
directory_update_init(). This should be changed to fully asynchronous
update later.
For this to work, main_notify has to be initialized before db_init().
The algorithm in addDirectoryPathToDB() can be simplified further if
it is combined with the function addParentPathToDB(). Since there is
no other caller of addDirectoryPathToDB(), we can do that. This saves
another large stack buffer.
This recursive function is very dangerous because it allocates a large
buffer on the stack in every iteration. That may be misused to
generate a stack overflow.
When a directory failed to update, it was removed from the database,
without freeing all children and songs (memory leak), and without
locking (race condition). Introduce the functions clear_directory()
and delete_directory(), which do both.
Commit 0bfe7802 broke update for new files in the root directory,
because music_root->path was an empty string and not NULL. There were
some NULL tests missing. Change them to !isRootDirectory(path)
instead of path!=NULL.
Taming the directory.c monster, part II: move the database management
stuff to database. directory.c should only contain code which works
on directory objects.
Instead of returning 0 or -1, return true on success and false on
failure. This seems more natural, and when the C library was
designed, there was no "bool" data type.
Provide separate constructors for creating a remote song, a local
song, and one for loading data from a song file. This way, we can add
more assertions.
exploreDirectory() duplicates some code in updateDirectory(). Merge
both functions, and use directory_is_empty() to determine whether
update or explore mode should be used.
The source directory.c mixes several libraries: directory object
management, database management and database update, resulting in a
1000+ line monster. Move the whole database update code to update.c.
