Manpages - sd_bus_wait.3
Table of Contents
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_sec parameter is specified, the call will block at most for the specified amount of time in µs. 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
These APIs are implemented as a shared library, which can be compiled and linked to with the libsystemd *pkg-config*(1) file.
SEE ALSO
*systemd*(1), *sd-bus*(3), *sd_bus_process*(3), *sd_bus_get_fd*(3), *sd-event*(3), *sd_bus_attach_event*(3)