sd_bus_set_fd — Set the file descriptors to use for bus communication
#include <systemd/sd-bus.h>
int sd_bus_set_fd( | sd_bus *bus, |
| int input_fd, | |
int output_fd); |
sd_bus_set_fd() sets the file descriptors used to communicate by a bus
connection object. Both input_fd and output_fd must be
valid file descriptors, referring to stream-based file objects (e.g. a stream socket, a pair of pipes or
FIFOs, or even a TTY device). input_fd must be readable, and
output_fd must be writable. The same file descriptor may be used (and typically is
used) as both the input and the output file descriptor. This function must be called before the bus
connection is started via
sd_bus_start(3).
The bus connection object will take possession of the passed file descriptors and will close them automatically when it is freed. Use sd_bus_set_close_on_exit(3) to turn off this behaviour.
On success, sd_bus_set_fd() returns a non-negative integer. On
failure, it returns a negative errno-style error code.
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().
-EBADF¶An invalid file descriptor was passed to
sd_bus_set_fd().
-ENOPKG¶The bus cannot be resolved.
-EPERM¶The bus connection has already been started.
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.