table of contents
- bookworm 252.30-1~deb12u2
- bookworm-backports 254.16-1~bpo12+1
- testing 256.7-2
- unstable 256.7-3
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 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
-ECHILD
-ENOTCONN
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)
systemd 256.7 |