libmpdclient  2.11
Enumerations | Functions
async.h File Reference

Asynchronous MPD connections. More...

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mpd_malloc struct mpd_asyncmpd_async_new (int fd)
void mpd_async_free (struct mpd_async *async)
mpd_pure enum mpd_error mpd_async_get_error (const struct mpd_async *async)
mpd_pure const char * mpd_async_get_error_message (const struct mpd_async *async)
mpd_pure int mpd_async_get_system_error (const struct mpd_async *async)
mpd_pure int mpd_async_get_fd (const struct mpd_async *async)
void mpd_async_set_keepalive (struct mpd_async *async, bool keepalive)
mpd_pure enum mpd_async_event mpd_async_events (const struct mpd_async *async)
bool mpd_async_io (struct mpd_async *async, enum mpd_async_event events)
bool mpd_async_send_command_v (struct mpd_async *async, const char *command, va_list args)
mpd_sentinel bool mpd_async_send_command (struct mpd_async *async, const char *command,...)
mpd_malloc char * mpd_async_recv_line (struct mpd_async *async)

Detailed Description

Asynchronous MPD connections.

This class provides a very basic interface to MPD connections. It does not know much about the MPD protocol, it does not know any specific MPD command.

The constructor expects a socket descriptor which is already connected to MPD. The first thing it does is read the server's handshake code ("OK MPD 0.15.0").

Definition in file async.h.

Enumeration Type Documentation

Event bit mask for polling.


ready to read from the file descriptor


ready to write to the file descriptor


hangup detected


I/O error

Definition at line 53 of file async.h.

Function Documentation

mpd_malloc struct mpd_async* mpd_async_new ( int  fd)

Creates a new asynchronous MPD connection, based on a stream socket connected with MPD.

fdthe socket file descriptor of the stream connection to MPD
a mpd_async object, or NULL on out of memory
void mpd_async_free ( struct mpd_async async)

Closes the socket and frees memory.

mpd_pure enum mpd_error mpd_async_get_error ( const struct mpd_async async)

After an error has occurred, this function returns the error code. If no error has occurred, it returns MPD_ERROR_SUCCESS.

mpd_pure const char* mpd_async_get_error_message ( const struct mpd_async async)

If mpd_async_is_alive() returns false, this function returns the human readable error message which caused this. This message is optional, and may be NULL. The pointer is invalidated by mpd_async_free().

For MPD_ERROR_SERVER, the error message is encoded in UTF-8. MPD_ERROR_SYSTEM obtains its error message from the operating system, and thus the locale's character set (and probably language) is used. Keep that in mind when you print error messages.

mpd_pure int mpd_async_get_system_error ( const struct mpd_async async)

Returns the error code from the operating system; on most operating systems, this is the errno value. Calling this function is only valid if mpd_async_get_error() returned MPD_ERROR_SYSTEM.

May be 0 if the operating system did not specify an error code.

mpd_pure int mpd_async_get_fd ( const struct mpd_async async)

Returns the file descriptor which should be polled by the caller. Do not use the file descriptor for anything except polling! The file descriptor never changes during the lifetime of this mpd_async object.

void mpd_async_set_keepalive ( struct mpd_async async,
bool  keepalive 

Enables (or disables) TCP keepalives.

Keepalives are enabled using the SO_KEEPALIVE socket option. They may be required for long-idled connections to persist on some networks that would otherwise terminate inactive TCP sessions.

The default value is false.

asyncthe mpd_async object
keepalivewhether TCP keepalives should be enabled
mpd_pure enum mpd_async_event mpd_async_events ( const struct mpd_async async)

Returns a bit mask of events which should be polled for.

bool mpd_async_io ( struct mpd_async async,
enum mpd_async_event  events 

Call this function when poll() has returned events for this object's file descriptor. libmpdclient will attempt to perform I/O operations.

false if the connection was closed due to an error
bool mpd_async_send_command_v ( struct mpd_async async,
const char *  command,
va_list  args 

Appends a command to the output buffer.

asyncthe connection
commandthe command name, followed by arguments, terminated by NULL
argsthe argument list
true on success, false if the buffer is full
mpd_sentinel bool mpd_async_send_command ( struct mpd_async async,
const char *  command,

Appends a command to the output buffer.

asyncthe connection
commandthe command name, followed by arguments, terminated by NULL
true on success, false if the buffer is full
mpd_malloc char* mpd_async_recv_line ( struct mpd_async async)

Receives a line from the input buffer. The result will be null-terminated, without the newline character. The pointer is only valid until the next async function is called.

asyncthe connection
a line on success, NULL otherwise