Man page - sd_bus_wait(3)

Packages contains this manual

Manual

SD_BUS_WAIT

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
Errors
NOTES
HISTORY
SEE ALSO

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 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

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.

HISTORY

sd_bus_wait() was added in version 240.

SEE ALSO

systemd (1), sd-bus (3), sd_bus_process (3), sd_bus_get_fd (3), sd-event (3), sd_bus_attach_event (3)