libuv

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <uv.h>

#include "s7/s7.h"

#define DEFAULT_PORT 7771
#define DEFAULT_BACKLOG 128


uv_loop_t *loop;
FILE *memstream;


static void s7Print(s7_scheme *sc, unsigned char c, s7_pointer port) {
  fputc(c, memstream);
}

void read_cb(uv_stream_t * stream, ssize_t nread, const uv_buf_t *buf) {
  /* dynamically allocate memory for a new write task */
  uv_write_t * req = (uv_write_t *) malloc(sizeof(uv_write_t));

  /* if read bytes counter -1 there is an error or EOF */
  if (nread == -1) {
    fprintf(stderr, "Error on reading client stream.\n");
    uv_close((uv_handle_t *) stream, NULL);
  }

  uv_buf_t outBuffer;
  memstream = open_memstream(&(outBuffer.base), &(outBuffer.len));

  s7_scheme *s7;
  s7 = s7_init();
  s7_set_current_output_port(s7, s7_open_output_function(s7, s7Print));
  s7_eval_c_string(s7, buf->base);

  /* Write sync the output buffer to the socket */
  fflush(memstream);
  int r = uv_write(req, stream, &outBuffer, 1, NULL);

  if (r < 0)
    fprintf(stderr, "Error on writing client stream.\n");

  /* free the remaining memory */
  free(buf->base);
}

void alloc_cb(uv_handle_t* handle, size_t suggested_size, uv_buf_t* buf) {
    buf->base = malloc(suggested_size);
    buf->len = suggested_size;
}

void connection_cb(uv_stream_t * stream, int status) {
  if (status < 0) {
    fprintf(stderr, "New connection error %s\n", uv_strerror(status));
    return;
  }

  uv_tcp_t client;
  uv_tcp_init(loop, &client);
  if (uv_accept(stream, (uv_stream_t*)&client) == 0) {
    uv_read_start((uv_stream_t*)&client, alloc_cb, read_cb);
    uv_write_t request;
    uv_buf_t prompt = { .base = "sonodi>", .len = 7 };

    if (uv_is_writable(stream))
      uv_write(&request, stream, &prompt, 1, NULL);
  }
  else {
    uv_close((uv_handle_t*)&client, NULL);
  }
}

int listenForConnections() {
  loop = uv_default_loop();

  uv_tcp_t server;
  uv_tcp_init(loop, &server);

  struct sockaddr_in addr;
  uv_ip4_addr("127.0.0.1", DEFAULT_PORT, &addr);

  uv_tcp_bind(&server, (const struct sockaddr*)&addr, 0);
  int r = uv_listen((uv_stream_t*) &server, DEFAULT_BACKLOG, connection_cb);
  if (r) {
    fprintf(stderr, "Listen error %s\n", uv_strerror(r));
    return 1;
  }
  return uv_run(loop, UV_RUN_DEFAULT);
}