commands should really not behave differently if they're issued
inside a command list or not; so stop having special handler
functions to deal with them. "update" was the only command
that used this functionality and I changed that in the last
commit to serialize access.
Now the "update" command can be issued multiple times regardless
of whether the client is in list mode or not.
We serialize the update tasks to prevent updates from trampling
over each other and will spawn another update task
once the current one is finished updating and reaped.
Right now we cap the queue size to 32 which is probably enough (I
bet most people usually run update with no argument anyways);
but we can make it grow/shrink dynamically if needed. There'll
still be a hard-coded limit to prevent DoS attacks, though.
This only breaks "update" under list command mode and
no other commands. This can be done more optimally
without the extra heap allocation via xstrdup(); but is
uncommon enough to not matter.
Due to a merge error, I broke the function handleUpdate(). It did not
do anything for the global update, and it did not send a proper
response to the client. This patch fixes both bugs.
A lot of the preparation was needed (and done in previous
months) in making update thread-safe, but here it is.
This was the first thing I made work inside a thread when I
started mpd-uclinux many years ago, and also the last thing I've
done in mainline mpd to work inside a thread, go figure.
print_playlist_result() had an assert(0) at the end, in case there was
an invalid result value. With NDEBUG, this resulted in a function not
returning a value - add a dummy "return -1" at the end to keep gcc
quiet.
The function loadPlaylist() wants to report incremental errors to the
client, for this reason we cannot remove its protocol dependency right
now. Instead, make it use the client struct instead of the raw file
descriptor.
Don't pass the raw file descriptor around. This migration patch is
rather large, because all of the sources have inter dependencies - we
have to change all of them at the same time.
Pass the client struct to CommandHandlerFunction and
CommandListHandlerFunction. Most commands cannot take real advantage
of that yet, since most of them still work with the raw file
descriptor.
These two functions take a client struct instead of the file
descriptor. We will now begin passing the client struct around
instead of a raw file descriptor (which needed a linear lookup in the
client list to be useful).
This patch continues the work of the previous patch: don't pass a file
descriptor at all to traverseAllIn(). Since this fd was only used to
report "directory not found" errors, we can easily move that check to
the caller. This is a great relief, since it removes the dependency
on a client connection from a lot of enumeration functions.
Continuing the effort of removing protocol specific calls from the
core libraries: let the command.c code call commandError() based on
PlaylistInfo's return value.
The playlist library shouldn't talk to the client if possible.
Introduce the "enum playlist_result" type which the caller
(i.e. command.c) may use to generate an error message.
Client's input values should be validated by the command
implementation, and the core libraries shouldn't talk to the client
directly if possible. Thus, setPlaylistRepeatStatus() and
setPlaylistRandomStatus() don't get the file descriptor, and cannot
fail (return void).
client_write() writes a buffer to the client and buffers it if
required. client_puts() does the same for a C string. The next patch
will add more tools which will replace fdprintf() later.
Instead of passing the pointer to the "expired" flag to
processListOfCommands(), this function should use the client API to
check this flag. We can now remove the "global_expired" hack
introduced recently.
Start exporting the client struct as an opaque struct. For now, pass
it only to processCommand() and processListOfCommands(), and provide a
function to extract the socket handle. Later, we will propagate the
pointer to all command implementations, and of course to
client_print() etc.
Also enable -Wunused-parameter - this forces us to add the gcc
"unused" attribute to a lot of parameters (mostly library callback
functions), but it's worth it during code refactorizations.
Try to only include headers which are really needed. We should
particularly check all "headers including other headers". The
long-term goal is to have a manageable, small API for plugins
(decoders, output) without so many mpd internals cluttering the
namespace.
git-svn-id: https://svn.musicpd.org/mpd/trunk@7319 09075e82-0dd4-0310-85a5-a0d7c8717e4f
Local variables which are never read before the first assignment don't
need initialization. Saves a few bytes of text. Also don't reset
variables which are never read until function return.
git-svn-id: https://svn.musicpd.org/mpd/trunk@7199 09075e82-0dd4-0310-85a5-a0d7c8717e4f
[ew: cleaned up the dirty union hack a bit]
Signed-off-by: Eric Wong <normalperson@yhbt.net>
git-svn-id: https://svn.musicpd.org/mpd/trunk@7180 09075e82-0dd4-0310-85a5-a0d7c8717e4f
It's too ugly and broken (both technically and usability-wise)
to be worth supporting in any stable release.
In one sentence: The queue is a very crippled version of the
playlist that takes precedence over the normal playlist.
How is it crippled?
* The "queueid" command only allows the queuing of songs
ALREADY IN THE PLAYLIST! This promotes having the entire mpd
database of songs in the playlist, which is a stupid practice
to begin with.
* It doesn't allow for meaningful rearranging and movement
of songs within the queue. To move a song, you'd need to
dequeue and requeue it (and other songs on the list).
Why? The playlist already allows _all_ these features
and shows everything a client needs to know about the ordering
of songs in a _single_ command!
* Random was a stupid idea to begin with and unfortunately
we're stuck supporting it since we've always had it. Users
should learn to use "shuffle" instead and not look at their
playlists. Implementing queue because we have the problem of
random is just a bandage fix and digging ourselves a new hole.
This protocol addition was never in a stable release of mpd, so
reverting it will only break things for people following trunk;
which I'm not too worried about. I am however worried about
long-term support of this misfeature, so I'm removing it.
Additionally, there are other points:
* It's trivially DoS-able:
(while true; do echo queueid $song_id; done) | nc $MPD_HOST $MPD_PORT
The above commands would cause the queue to become infinitely
expanding, taking up all available memory in the system. The
mpd playlist was implemented as an array with a fixed (but
configurable) size limit for this reason.
* It's not backwards-compatible. All clients would require
upgrades (and additional complexity) to even know what the
next song in the playlist is. mpd is a shared architecture,
and we should not violate the principle of least astonishment
here.
This removes the following commands:
queueid, dequeue, queueinfo
Additionally, the status field of "playlistqueue: " is removed
from the status command.
While this DoS is trivial to fix, the design is simply too
broken to ever support in a real release.
The overloading of the "addid" command and the allowing of
negative numbers to be used as offsets is far more flexible.
This improved "addid" is completely backwards-compatible with
all clients, and does not require clients to have UI changes or
run additional commands to display the queue.
git-svn-id: https://svn.musicpd.org/mpd/trunk@7155 09075e82-0dd4-0310-85a5-a0d7c8717e4f
This will allow "addid \"song_url\" <pos>" to atomically insert a
song at any given playlist position.
If the add succeeds, but the actual movement fails (due to
invalid position), then the song_id will be deleted before
the command returns back to the client, and the client
will get an error response.
git-svn-id: https://svn.musicpd.org/mpd/trunk@7151 09075e82-0dd4-0310-85a5-a0d7c8717e4f
