|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | NOTES | COLOPHON |
SD_BUS_ADD_MATCH(3) sd_bus_add_match SD_BUS_ADD_MATCH(3)
sd_bus_add_match - Add a match rule for message dispatching
#include <systemd/sd-bus.h>
int sd_bus_add_match(sd_bus *bus, sd_bus_slot **slot,
const char *match,
sd_bus_message_handler_t callback,
void *userdata);
typedef int (*sd_bus_message_handler_t)(sd_bus_message *m,
void *userdata,
sd_bus_error *ret_error);
sd_bus_add_match() installs a match rule for incoming messages
received on the specified bus connection object bus. The syntax of
the match rule expression passed in match is described in the D-Bus
Specification[1]. The specified handler function callback is called
for eaching incoming message matching the specified expression, the
userdata parameter is passed as-is to the callback function.
On success, and if non-NULL, the slot return parameter will be set to
a slot object that may be used as a reference to the installed match,
and may be utilized to remove it again at a later time with
sd_bus_slot_unref(3). If specified as NULL the lifetime of the match
is bound to the lifetime of the bus object itself, and the match
cannot be removed independently.
The message m passed to the callback is only borrowed, that is, the
callback should not call sd_bus_message_unref(3) on it. If the
callback wants to hold on to the message beyond the lifetime of the
callback, it needs to call sd_bus_message_ref(3) to create a new
reference.
If an error occurs during the callback invocation, the callback
should return a negative error number. If it wants other callbacks
that match the same rule to be called, it should return 0. Otherwise
it should return a positive integer.
On success, sd_bus_add_match() returns 0 or a positive integer. On
failure, it returns a negative errno-style error code.
systemd(1), sd-bus(3)
1. D-Bus Specification
https://dbus.freedesktop.org/doc/dbus-specification.html
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systemd 234 SD_BUS_ADD_MATCH(3)
Pages that refer to this page: busctl(1), systemd.directives(7), systemd.index(7)