Demo C port program for Erlang/Elixir

port_demo.c

#include <unistd.h>
#include <stdint.h>
#include <errno.h>
#include <arpa/inet.h>

int
read_packet(unsigned char *buffer)
{
        ssize_t nr;
        uint16_t packet_size;

        if ((nr = read(0, &packet_size, 2)) != 2) {
                return nr;
        }

        packet_size = ntohs(packet_size);

        return read(0, buffer, packet_size);
}

int
write_packet(unsigned char *buffer, uint16_t packet_size)
{
        ssize_t nr;
        uint16_t _packet_size;

        _packet_size = htons(packet_size);

        if ((nr = write(1, &_packet_size, 2)) != 2) {
                return nr;
        }

        return write(1, buffer, packet_size);
}

int
main(int argc, char **argv)
{
        unsigned char buffer[65535];
        ssize_t nr;

        while ((nr = read_packet(buffer)) != -1 && nr != 0) {
                write_packet(buffer, nr);
        }

        if (errno) {
                perror("error");
        }

        return -1;
}