sd_bus_set_fd - Set the file descriptors to use for bus communication
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:
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.