1SD_BUS_WAIT(3) sd_bus_wait SD_BUS_WAIT(3)
2
3
4
6 sd_bus_wait - Wait for I/O on a bus connection
7
9 #include <systemd/sd-bus.h>
10
11 int sd_bus_wait(sd_bus *bus, uint64_t timeout_usec);
12
14 sd_bus_wait() synchronously waits for I/O on the specified bus
15 connection object. This function is supposed to be called whenever
16 sd_bus_process(3) returns zero, indicating that no work is pending on
17 the connection. Internally, this call invokes ppoll(2), to wait for I/O
18 on the bus connection. If the timeout_usec parameter is specified, the
19 call will block at most for the specified amount of time in μs. Pass
20 UINT64_MAX to permit it to sleep indefinitely.
21
22 After each invocation of sd_bus_wait() the sd_bus_process() call should
23 be invoked in order to process any now pending I/O work.
24
25 Note that sd_bus_wait() is suitable only for simple programs as it does
26 not permit waiting for other I/O events. For more complex programs
27 either connect the bus connection object to an external event loop
28 using sd_bus_get_fd(3) or to an sd-event(3) event loop using
29 sd_bus_attach_event(3).
30
32 If any I/O was seen, a positive value is returned, zero otherwise. If
33 an error occurs, a negative errno-style error code is returned.
34
35 Errors
36 Returned errors may indicate the following problems:
37
38 -EINVAL
39 An invalid bus object was passed.
40
41 -ECHILD
42 The bus connection was allocated in a parent process and is being
43 reused in a child process after fork().
44
45 -ENOTCONN
46 The bus connection has been terminated already.
47
49 Functions described here are available as a shared library, which can
50 be compiled against and linked to with the libsystemd pkg-config(1)
51 file.
52
53 The code described here uses getenv(3), which is declared to be not
54 multi-thread-safe. This means that the code calling the functions
55 described here must not call setenv(3) from a parallel thread. It is
56 recommended to only do calls to setenv() from an early phase of the
57 program when no other threads have been started.
58
60 systemd(1), sd-bus(3), sd_bus_process(3), sd_bus_get_fd(3), sd-
61 event(3), sd_bus_attach_event(3)
62
63
64
65systemd 254 SD_BUS_WAIT(3)