1SD_BUS_WAIT(3) sd_bus_wait SD_BUS_WAIT(3)
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6 sd_bus_wait - Wait for I/O on a bus connection
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9 #include <systemd/sd-bus.h>
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11 int sd_bus_wait(sd_bus *bus, uint64_t timeout_usec);
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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(3), to wait for I/O
18 on the bus connection. If the timeout_sec 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.
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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.
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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).
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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.
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36 Returned errors may indicate the following problems:
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38 -EINVAL
39 An invalid bus object was passed.
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41 -ECHILD
42 The bus connection was allocated in a parent process and is being
43 reused in a child process after fork().
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45 -ENOTCONN
46 The bus connection has been terminated already.
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49 These APIs are implemented as a shared library, which can be compiled
50 and linked to with the libsystemd pkg-config(1) file.
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53 systemd(1), sd-bus(3), sd_bus_process(3), sd_bus_get_fd(3), sd-
54 event(3), sd_bus_attach_event(3)
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58systemd 241 SD_BUS_WAIT(3)