x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_BUS_WAIT(3) sd_bus_wait SD_BUS_WAIT(3)
NAME
sd_bus_wait - Wait for I/O on a bus connection
SYNOPSIS
#include <systemd/sd-bus.h>
int sd_bus_wait(sd_bus *bus, uint64_t timeout_usec);
DESCRIPTION
sd_bus_wait() synchronously waits for I/O on the specified bus
connection object. This function is supposed to be called whenever
sd_bus_process(3) returns zero, indicating that no work is pending on
the connection. Internally, this call invokes ppoll(2), to wait for I/O
on the bus connection. If the timeout_usec parameter is specified, the
call will block at most for the specified amount of time in <mu>s. Pass
UINT64_MAX to permit it to sleep indefinitely.
After each invocation of sd_bus_wait() the sd_bus_process() call should
be invoked in order to process any now pending I/O work.
Note that sd_bus_wait() is suitable only for simple programs as it does
not permit waiting for other I/O events. For more complex programs
either connect the bus connection object to an external event loop
using sd_bus_get_fd(3) or to an sd-event(3) event loop using
sd_bus_attach_event(3).
RETURN VALUE
If any I/O was seen, a positive value is returned, zero otherwise. If
an error occurs, a negative errno-style error code is returned.
Errors
Returned errors may indicate the following problems:
-EINVAL
An invalid bus object was passed.
-ECHILD
The bus connection was allocated in a parent process and is being
reused in a child process after fork().
-ENOTCONN
The bus connection has been terminated already.
NOTES
Functions described here are available as a shared library, which can
be compiled against and linked to with the libsystemd pkg-config(1)
file.
The code described here uses getenv(3), which is declared to be not
multi-thread-safe. This means that the code calling the functions
described here must not call setenv(3) from a parallel thread. It is
recommended to only do calls to setenv() from an early phase of the
program when no other threads have been started.
SEE ALSO
systemd(1), sd-bus(3), sd_bus_process(3), sd_bus_get_fd(3), sd-
event(3), sd_bus_attach_event(3)
systemd 254 SD_BUS_WAIT(3)
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