urbit/v/term.c

/* v/term.c
**
** This file is in the public domain.
*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <setjmp.h>
#include <gmp.h>
#include <stdint.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <uv.h>
#include <errno.h>
#include <curses.h>
#include <termios.h>
#include <term.h>

#include "all.h"
#include "v/vere.h"

static void _term_read_tn_cb(uv_stream_t*, ssize_t, uv_buf_t);
static void _term_read_cb(uv_stream_t*, ssize_t, uv_buf_t);

/* _term_alloc(): libuv buffer allocator.
*/
static uv_buf_t
_term_alloc(uv_handle_t* had_u, size_t len_i)
{
  return uv_buf_init(c3_malloc(len_i), len_i);
}

/* _term_close_cb(): free terminal.
*/
static void
_term_close_cb(uv_handle_t* han_t)
{
  u2_utty* uty_u = (void*) han_t;
  free(uty_u);
}

/* u2_term_io_init(): initialize terminal.
*/
void
u2_term_io_init()
{
  u2_utty* uty_u = calloc(1, sizeof(u2_utty));

  if ( u2_yes == u2_Host.ops_u.dem ) {
    uty_u->fid_i = 1;

    uv_pipe_init(u2L, &(uty_u->pop_u), 0);
    uv_pipe_open(&(uty_u->pop_u), uty_u->fid_i);
  }
  else {
    //  Initialize event processing.  Rawdog it.
    //
    {
      uty_u->fid_i = 0;                       //  stdin, yes we write to it...

      uv_pipe_init(u2L, &(uty_u->pop_u), 0);
      uv_pipe_open(&(uty_u->pop_u), uty_u->fid_i);
      uv_read_start((uv_stream_t*)&(uty_u->pop_u), _term_alloc, _term_read_cb);
    }

    //  Configure horrible stateful terminfo api.
    //
    {
      if ( 0 != setupterm(0, 2, 0) ) {
        c3_assert(!"init-setupterm");
      }
    }

    //  Load terminfo strings.
    //
    {
      c3_w len_w;

#   define _utfo(way, nam) \
      { \
        uty_u->ufo_u.way.nam##_y = (const c3_y *) tigetstr(#nam); \
        c3_assert(uty_u->ufo_u.way.nam##_y); \
      }

      uty_u->ufo_u.inn.max_w = 0;

#if 1
      _utfo(inn, kcuu1);
      _utfo(inn, kcud1);
      _utfo(inn, kcub1);
      _utfo(inn, kcuf1);

      _utfo(out, clear);
      _utfo(out, el);
      // _utfo(out, el1);
      _utfo(out, ed);
      _utfo(out, bel);
      _utfo(out, cub1);
      _utfo(out, cuf1);
      _utfo(out, cuu1);
      _utfo(out, cud1);
      // _utfo(out, cub);
      // _utfo(out, cuf);
#else
      //  libuv hardcodes an ansi terminal - which doesn't seem to work...
      //
      uty_u->ufo_u.out.clear_y = "\033[H\033[J";
      uty_u->ufo_u.out.el_y = "\033[K";
      uty_u->ufo_u.out.ed_y = "\033[J";
      uty_u->ufo_u.out.bel_y = "\007";
      uty_u->ufo_u.out.cub1_y = "\010";
      uty_u->ufo_u.out.cud1_y = "\033[B";
      uty_u->ufo_u.out.cuu1_y = "\033[A";
      uty_u->ufo_u.out.cuf1_y = "\033[C";
#endif

      //  Terminfo chronically reports the wrong sequence for arrow
      //  keys on xterms.  Drastic fix for ridiculous unacceptable bug.
      //  Yes, we could fix this with smkx/rmkx, but this is retarded as well.
      {
        uty_u->ufo_u.inn.kcuu1_y = (const c3_y*)"\033[A";
        uty_u->ufo_u.inn.kcud1_y = (const c3_y*)"\033[B";
        uty_u->ufo_u.inn.kcuf1_y = (const c3_y*)"\033[C";
        uty_u->ufo_u.inn.kcub1_y = (const c3_y*)"\033[D";
      }

      uty_u->ufo_u.inn.max_w = 0;
      if ( (len_w = strlen((c3_c*)uty_u->ufo_u.inn.kcuu1_y)) >
            uty_u->ufo_u.inn.max_w )
      {
        uty_u->ufo_u.inn.max_w = len_w;
      }
      if ( (len_w = strlen((c3_c*)uty_u->ufo_u.inn.kcud1_y)) >
            uty_u->ufo_u.inn.max_w )
      {
        uty_u->ufo_u.inn.max_w = len_w;
      }
      if ( (len_w = strlen((c3_c*)uty_u->ufo_u.inn.kcub1_y)) >
            uty_u->ufo_u.inn.max_w )
      {
        uty_u->ufo_u.inn.max_w = len_w;
      }
      if ( (len_w = strlen((c3_c*)uty_u->ufo_u.inn.kcuf1_y)) >
            uty_u->ufo_u.inn.max_w )
      {
        uty_u->ufo_u.inn.max_w = len_w;
      }
    }

    //  Load old terminal state to restore.
    //
#if 1
    {
      if ( 0 != tcgetattr(uty_u->fid_i, &uty_u->bak_u) ) {
        c3_assert(!"init-tcgetattr");
      }
      if ( -1 == fcntl(uty_u->fid_i, F_GETFL, &uty_u->cug_i) ) {
        c3_assert(!"init-fcntl");
      }
      uty_u->cug_i &= ~O_NONBLOCK;                // could fix?
      uty_u->nob_i = uty_u->cug_i | O_NONBLOCK;   // O_NDELAY on older unix
    }

    //  Construct raw termios configuration.
    //
    {
      uty_u->raw_u = uty_u->bak_u;

      uty_u->raw_u.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
      uty_u->raw_u.c_iflag &= ~(ICRNL | INPCK | ISTRIP);
      uty_u->raw_u.c_cflag &= ~(CSIZE | PARENB);
      uty_u->raw_u.c_cflag |= CS8;
      uty_u->raw_u.c_oflag &= ~(OPOST);
      uty_u->raw_u.c_cc[VMIN] = 0;
      uty_u->raw_u.c_cc[VTIME] = 0;
    }
#endif

    //  Initialize mirror and accumulator state.
    //
    {
      uty_u->tat_u.mir.lin_w = 0;
      uty_u->tat_u.mir.len_w = 0;
      uty_u->tat_u.mir.cus_w = 0;

      uty_u->tat_u.esc.ape = u2_no;
      uty_u->tat_u.esc.bra = u2_no;

      uty_u->tat_u.fut.len_w = 0;
      uty_u->tat_u.fut.wid_w = 0;
    }
  }

  //  This is terminal 1, linked in host.
  //
  {
    uty_u->tid_l = 1;

    uty_u->nex_u = u2_Host.uty_u;
    u2_Host.uty_u = uty_u;
    u2_Host.tem_u = uty_u;
  }

  if ( u2_no == u2_Host.ops_u.dem ) {
    //  Start raw input.
    //
    {
      if ( 0 != tcsetattr(uty_u->fid_i, TCSADRAIN, &uty_u->raw_u) ) {
        c3_assert(!"init-tcsetattr");
      }
      if ( -1 == fcntl(uty_u->fid_i, F_SETFL, uty_u->nob_i) ) {
        c3_assert(!"init-fcntl");
      }
    }
  }
}

void
_term_listen_cb(uv_stream_t *wax_u, int sas_i)
{
  u2_utty* tty_u = calloc(1, sizeof(*tty_u));
  uv_tcp_init(u2L, &tty_u->wax_u);
  if ( 0 != uv_accept(wax_u, (uv_stream_t*)&tty_u->wax_u) ) {
    uL(fprintf(uH, "term: accept: %s\n",
                    uv_strerror(uv_last_error(u2L))));

    uv_close((uv_handle_t*)&tty_u->wax_u, _term_close_cb);
  }
  else {
    uv_read_start((uv_stream_t*)&tty_u->wax_u,
                  _term_alloc,
                  _term_read_tn_cb);

    tty_u->ufo_u.out.clear_y = (const c3_y*)"\033[H\033[J";
    tty_u->ufo_u.out.el_y    = (const c3_y*)"\033[K";
    tty_u->ufo_u.out.ed_y    = (const c3_y*)"\033[J";
    tty_u->ufo_u.out.bel_y   = (const c3_y*)"\007";
    tty_u->ufo_u.out.cub1_y  = (const c3_y*)"\010";
    tty_u->ufo_u.out.cud1_y  = (const c3_y*)"\033[B";
    tty_u->ufo_u.out.cuu1_y  = (const c3_y*)"\033[A";
    tty_u->ufo_u.out.cuf1_y  = (const c3_y*)"\033[C";

    tty_u->ufo_u.inn.kcuu1_y = (const c3_y*)"\033[A";
    tty_u->ufo_u.inn.kcud1_y = (const c3_y*)"\033[B";
    tty_u->ufo_u.inn.kcuf1_y = (const c3_y*)"\033[C";
    tty_u->ufo_u.inn.kcub1_y = (const c3_y*)"\033[D";
    tty_u->ufo_u.inn.max_w = strlen("\033[D");

    tty_u->fid_i = -1;

    tty_u->tat_u.mir.lin_w = 0;
    tty_u->tat_u.mir.len_w = 0;
    tty_u->tat_u.mir.cus_w = 0;

    tty_u->tat_u.esc.ape = u2_no;
    tty_u->tat_u.esc.bra = u2_no;

    tty_u->tat_u.fut.len_w = 0;
    tty_u->tat_u.fut.wid_w = 0;

    tty_u->tid_l = u2_Host.uty_u->tid_l + 1;
    tty_u->nex_u = u2_Host.uty_u;

    u2_Host.uty_u = tty_u;

    {
      u2_noun tid = u2_dc("scot", c3__ud, tty_u->tid_l);
      u2_noun pax = u2nq(c3__gold, c3__term, tid, u2_nul);
      u2_reck_plan(u2A, u2k(pax), u2nc(c3__blew, u2_term_get_blew(1)));
      u2_reck_plan(u2A, u2k(pax), u2nc(c3__hail, u2_nul));
      u2z(pax);
    }
  }
}

void
u2_term_io_talk(void)
{
  struct sockaddr_in add_u;
  u2_utel* tel_u = &u2_Host.tel_u;

  uv_tcp_init(u2L, &tel_u->wax_u);
  tel_u->por_s = 10023;

  memset(&add_u, 0, sizeof(add_u));
  add_u.sin_family = AF_INET;
  add_u.sin_addr.s_addr = htonl(INADDR_LOOPBACK);

  /*  Try ascending ports.
  */
  while ( 1 ) {
    add_u.sin_port = htons(tel_u->por_s);

    if ( 0 != uv_tcp_bind(&tel_u->wax_u, add_u)  ) {
      uv_err_t las_u = uv_last_error(u2L);

      if ( UV_EADDRINUSE == las_u.code ) {
        tel_u->por_s++;
        continue;
      }
      else {
        uL(fprintf(uH, "term: bind: %s\n", uv_strerror(las_u)));
      }
    }
    if ( 0 != uv_listen((uv_stream_t*)&tel_u->wax_u, 16, _term_listen_cb) ) {
      uv_err_t las_u = uv_last_error(u2L);

      if ( UV_EADDRINUSE == las_u.code ) {
        tel_u->por_s++;
        continue;
      }
      else {
        uL(fprintf(uH, "term: listen: %s\n", uv_strerror(las_u)));
      }
    }
    uL(fprintf(uH, "term: live on %d\n", tel_u->por_s));
    break;
  }
}

/* u2_term_io_exit(): clean up terminal.
*/
void
u2_term_io_exit(void)
{
  if ( u2_yes == u2_Host.ops_u.dem ) {
    uv_close((uv_handle_t*)&u2_Host.uty_u->pop_u, NULL);
  }
  else {
    u2_utty* uty_u;

    for ( uty_u = u2_Host.uty_u; uty_u; uty_u = uty_u->nex_u ) {
      if ( uty_u->fid_i == -1 ) { continue; }
      if ( 0 != tcsetattr(uty_u->fid_i, TCSADRAIN, &uty_u->bak_u) ) {
        c3_assert(!"exit-tcsetattr");
      }
      if ( -1 == fcntl(uty_u->fid_i, F_SETFL, uty_u->cug_i) ) {
        c3_assert(!"exit-fcntl");
      }
      write(uty_u->fid_i, "\r\n", 2);
    }
  }
}

void
u2_term_io_poll(void)
{
}

/* _term_it_buf(): create a data buffer.
*/
static u2_ubuf*
_term_it_buf(c3_w len_w, const c3_y* hun_y)
{
  u2_ubuf* buf_u = c3_malloc(len_w + sizeof(*buf_u));

  buf_u->len_w = len_w;
  memcpy(buf_u->hun_y, hun_y, len_w);

  buf_u->nex_u = 0;
  return buf_u;
}

/* An unusual lameness in libuv.
*/
  typedef struct {
    uv_write_t wri_u;
    c3_y*      buf_y;
  } _u2_write_t;

/* _term_write_cb(): general write callback.
*/
static void
_term_write_cb(uv_write_t* wri_u, c3_i sas_i)
{
  _u2_write_t* ruq_u = (void *)wri_u;

  if ( 0 != sas_i ) {
    uL(fprintf(uH, "term: write: %s\n", uv_strerror(uv_last_error(u2L))));
  }
  free(ruq_u->buf_y);
  free(ruq_u);
}

/* _term_it_write_buf(): write buffer uv style.
*/
static void
_term_it_write_buf(u2_utty* uty_u, uv_buf_t buf_u)
{
  _u2_write_t* ruq_u = (_u2_write_t*) c3_malloc(sizeof(_u2_write_t));

  ruq_u->buf_y = (c3_y*)buf_u.base;

  if ( 0 != uv_write(&ruq_u->wri_u,
                     (uv_stream_t*)&(uty_u->pop_u),
                     &buf_u, 1,
                     _term_write_cb) )
  {
    uL(fprintf(uH, "terminal: %s\n", uv_strerror(uv_last_error(u2L))));
  }
}

/* _term_it_write_old(): write buffer, transferring pointer.
*/
static void
_term_it_write_old(u2_utty* uty_u,
                   u2_ubuf* old_u)
{
  uv_buf_t buf_u;

  //  XX extra copy here due to old code.  Use hbod as base directly.
  //
  {
    c3_y* buf_y = c3_malloc(old_u->len_w);

    memcpy(buf_y, old_u->hun_y, old_u->len_w);
    buf_u = uv_buf_init((c3_c*)buf_y, old_u->len_w);

    free(old_u);
  }
  _term_it_write_buf(uty_u, buf_u);
}

/* _term_it_write_bytes(): write bytes, retaining pointer.
*/
static void
_term_it_write_bytes(u2_utty*    uty_u,
                     c3_w        len_w,
                     const c3_y* hun_y)
{
  _term_it_write_old(uty_u, _term_it_buf(len_w, hun_y));
}

/* _term_it_write_txt(): write null-terminated string, retaining pointer.
*/
static void
_term_it_write_txt(u2_utty*    uty_u,
                   const c3_y* hun_y)
{
  _term_it_write_bytes(uty_u, strlen((const c3_c*)hun_y), hun_y);
}

/* _term_it_write_str(): write null-terminated string, retaining pointer.
*/
static void
_term_it_write_str(u2_utty*    uty_u,
                   const c3_c* str_c)
{
  _term_it_write_txt(uty_u, (const c3_y*) str_c);
}

/* _term_it_show_wide(): show wide text, retaining.
*/
static void
_term_it_show_wide(u2_utty* uty_u, c3_w len_w, c3_w* txt_w)
{
  u2_noun wad   = u2_ci_words(len_w, txt_w);
  u2_noun txt   = u2_do("tuft", wad);
  c3_c*   txt_c = u2_cr_string(txt);

  _term_it_write_str(uty_u, txt_c);
  free(txt_c);
  u2z(txt);

  uty_u->tat_u.mir.cus_w += len_w;
}

/* _term_it_show_clear(): clear to the beginning of the current line.
*/
static void
_term_it_show_clear(u2_utty* uty_u)
{
  u2_utat* tat_u = &uty_u->tat_u;

  if ( tat_u->siz.col_l ) {
    c3_w     ful_w = tat_u->mir.cus_w / tat_u->siz.col_l;

    if ( 0 != tat_u->mir.cus_w &&
         ful_w * tat_u->siz.col_l == tat_u->mir.cus_w )
    {
      ful_w--;
    }

    while ( ful_w-- ) {
      _term_it_write_txt(uty_u, uty_u->ufo_u.out.cuu1_y);
    }

    _term_it_write_str(uty_u, "\r");
    _term_it_write_txt(uty_u, uty_u->ufo_u.out.ed_y);

    tat_u->mir.len_w = 0;
    tat_u->mir.cus_w = 0;
  }
}

/* _term_it_show_blank(): blank the screen.
*/
static void
_term_it_show_blank(u2_utty* uty_u)
{
  _term_it_write_txt(uty_u, uty_u->ufo_u.out.clear_y);
  uty_u->tat_u.mir.cus_w = 0;
}

/* _term_it_show_cursor(): set current line, transferring pointer.
*/
static void
_term_it_show_cursor(u2_utty* uty_u, c3_w cur_w)
{
  if ( cur_w < uty_u->tat_u.mir.cus_w ) {
    c3_w dif_w = (uty_u->tat_u.mir.cus_w - cur_w);

    while ( dif_w-- ) {
      _term_it_write_txt(uty_u, uty_u->ufo_u.out.cub1_y);
    }
  }
  else if ( cur_w > uty_u->tat_u.mir.cus_w ) {
    c3_w dif_w = (cur_w - uty_u->tat_u.mir.cus_w);

    while ( dif_w-- ) {
      _term_it_write_txt(uty_u, uty_u->ufo_u.out.cuf1_y);
    }
  }
  uty_u->tat_u.mir.cus_w = cur_w;
}

/* _term_it_show_line(): set current line
*/
static void
_term_it_show_line(u2_utty* uty_u, c3_w* lin_w, c3_w len_w)
{
  _term_it_show_wide(uty_u, len_w, lin_w);

  if ( lin_w != uty_u->tat_u.mir.lin_w ) {
    if ( uty_u->tat_u.mir.lin_w ) {
      free(uty_u->tat_u.mir.lin_w);
    }
    uty_u->tat_u.mir.lin_w = lin_w;
  }
  uty_u->tat_u.mir.len_w = len_w;
}

/* _term_it_refresh_line(): refresh current line.
*/
static void
_term_it_refresh_line(u2_utty* uty_u)
{
  c3_w len_w = uty_u->tat_u.mir.len_w;

  _term_it_show_clear(uty_u);
  _term_it_show_wide(uty_u, len_w, uty_u->tat_u.mir.lin_w);
}

/* _term_it_show_more(): new current line.
*/
static void
_term_it_show_more(u2_utty* uty_u)
{
  if ( u2_yes == u2_Host.ops_u.dem ) {
    _term_it_write_str(uty_u, "\n");
  } else {
    _term_it_write_str(uty_u, "\r\n");
  }
  uty_u->tat_u.mir.cus_w = 0;
}

/* _term_it_path(): path for console file.
*/
static c3_c*
_term_it_path(u2_bean fyl, u2_noun pax)
{
  c3_w len_w;
  c3_c *pas_c;

  //  measure
  //
  len_w = strlen(u2_Host.cpu_c);
  {
    u2_noun wiz = pax;

    while ( u2_nul != wiz ) {
      len_w += (1 + u2_cr_met(3, u2h(wiz)));
      wiz = u2t(wiz);
    }
  }

  //  cut
  //
  pas_c = c3_malloc(len_w + 1);
  strncpy(pas_c, u2_Host.cpu_c, len_w);
  pas_c[len_w] = '\0';
  {
    u2_noun wiz   = pax;
    c3_c*   waq_c = (pas_c + strlen(pas_c));

    while ( u2_nul != wiz ) {
      c3_w tis_w = u2_cr_met(3, u2h(wiz));

      if ( (u2_yes == fyl) && (u2_nul == u2t(wiz)) ) {
        *waq_c++ = '.';
      } else *waq_c++ = '/';

      u2_cr_bytes(0, tis_w, (c3_y*)waq_c, u2h(wiz));
      waq_c += tis_w;

      wiz = u2t(wiz);
    }
    *waq_c = 0;
  }
  u2z(pax);
  return pas_c;
}

/* _term_it_save(): save file by path.
*/
static void
_term_it_save(u2_noun pax, u2_noun pad)
{
  c3_c* pax_c;

  pax = u2nt(c3_s4('.','u','r','b'), c3_s3('p','u','t'), pax);
  pax_c = _term_it_path(u2_yes, pax);

  u2_walk_save(pax_c, 0, pad);
  free(pax_c);
}

/* _term_io_belt(): send belt.
*/
static void
_term_io_belt(u2_utty* uty_u, u2_noun  blb)
{
  u2_noun tid = u2_dc("scot", c3__ud, uty_u->tid_l);
  u2_noun pax = u2nq(c3__gold, c3__term, tid, u2_nul);

  u2_reck_plan(u2A, pax, u2nc(c3__belt, blb));
}

/* _term_io_suck_char(): process a single character.
*/
static void
_term_io_suck_char(u2_utty* uty_u, c3_y cay_y)
{
  u2_utat* tat_u = &uty_u->tat_u;

  if ( u2_yes == tat_u->esc.ape ) {
    if ( u2_yes == tat_u->esc.bra ) {
      switch ( cay_y ) {
        default: {
          _term_it_write_txt(uty_u, uty_u->ufo_u.out.bel_y);
          break;
        }
        case 'A': _term_io_belt(uty_u, u2nc(c3__aro, 'u')); break;
        case 'B': _term_io_belt(uty_u, u2nc(c3__aro, 'd')); break;
        case 'C': _term_io_belt(uty_u, u2nc(c3__aro, 'r')); break;
        case 'D': _term_io_belt(uty_u, u2nc(c3__aro, 'l')); break;
      }
      tat_u->esc.ape = tat_u->esc.bra = u2_no;
    }
    else {
      if ( (cay_y >= 'a') && (cay_y <= 'z') ) {
        tat_u->esc.ape = u2_no;
        _term_io_belt(uty_u, u2nc(c3__met, cay_y));
      }
      else if ( ('[' == cay_y) || ('O' == cay_y) ) {
        tat_u->esc.bra = u2_yes;
      }
      else {
        tat_u->esc.ape = u2_no;

        _term_it_write_txt(uty_u, uty_u->ufo_u.out.bel_y);
      }
    }
  }
  else if ( 0 != tat_u->fut.wid_w ) {
    tat_u->fut.syb_y[tat_u->fut.len_w++] = cay_y;

    if ( tat_u->fut.len_w == tat_u->fut.wid_w ) {
      u2_noun huv = u2_ci_bytes(tat_u->fut.wid_w, tat_u->fut.syb_y);
      u2_noun wug;

      // uL(fprintf(uH, "muck-utf8 len %d\n", tat_u->fut.len_w));
      // uL(fprintf(uH, "muck-utf8 %x\n", huv));
      wug = u2_do("turf", huv);
      // uL(fprintf(uH, "muck-utf32 %x\n", tat_u->fut.len_w));

      tat_u->fut.len_w = tat_u->fut.wid_w = 0;
      _term_io_belt(uty_u, u2nt(c3__txt, wug, u2_nul));
    }
  }
  else {
    if ( (cay_y >= 32) && (cay_y < 127) ) {
      _term_io_belt(uty_u, u2nt(c3__txt, cay_y, u2_nul));
    }
    else if ( 0 == cay_y ) {
      _term_it_write_txt(uty_u, uty_u->ufo_u.out.bel_y);
    }
    else if ( 8 == cay_y || 127 == cay_y ) {
      _term_io_belt(uty_u, u2nc(c3__bac, u2_nul));
    }
    else if ( 13 == cay_y ) {
      _term_io_belt(uty_u, u2nc(c3__ret, u2_nul));
    }
    else if ( cay_y <= 26 ) {
      _term_io_belt(uty_u, u2nc(c3__ctl, ('a' + (cay_y - 1))));
    }
    else if ( 27 == cay_y ) {
      tat_u->esc.ape = u2_yes;
    }
    else if ( cay_y >= 128 ) {
      tat_u->fut.len_w = 1;
      tat_u->fut.syb_y[0] = cay_y;

      if ( cay_y <= 224 ) {
        tat_u->fut.wid_w = 2;
      } else if ( cay_y <= 240 ) {
        tat_u->fut.wid_w = 3;
      } else tat_u->fut.wid_w = 4;
    }
  }
}

/* _term_read_tn_cb(): telnet read callback.
*/
static void
_term_read_tn_cb(uv_stream_t* str_u,
                 ssize_t      siz_i,
                 uv_buf_t     buf_u)
{
  u2_utty* uty_u = (u2_utty*)(void*)str_u;

  u2_lo_open();
  {
    if ( siz_i < 0 ) {
      uv_err_t las_u = uv_last_error(u2L);

      uL(fprintf(uH, "term %d: read: %s\n", uty_u->tid_l, uv_strerror(las_u)));
      if ( uty_u->tid_l != 1 ) {
        uv_close((uv_handle_t*)str_u, _term_close_cb);
      }
    }
    else {
      c3_i i;

      for ( i=0; i < siz_i; i++ ) {
        if ( 10 != buf_u.base[i] ) {
          _term_io_suck_char(uty_u, buf_u.base[i]);
        }
      }
    }

    if ( buf_u.base ) {
      free(buf_u.base);
    }
  }
  u2_lo_shut(u2_yes);
}

/* _term_read_cb(): server read callback.
*/
static void
_term_read_cb(uv_stream_t* str_u,
              ssize_t      siz_i,
              uv_buf_t     buf_u)
{
  u2_utty* uty_u = (u2_utty*)(void*)str_u;

  u2_lo_open();
  {
    if ( siz_i < 0 ) {
      uv_err_t las_u = uv_last_error(u2L);

      uL(fprintf(uH, "term %d: read: %s\n", uty_u->tid_l, uv_strerror(las_u)));
    }
    else {
      c3_i i;

      for ( i=0; i < siz_i; i++ ) {
        _term_io_suck_char(uty_u, buf_u.base[i]);
      }
    }

    if ( buf_u.base ) {
      free(buf_u.base);
    }
  }
  u2_lo_shut(u2_yes);
}

/* _term_main(): return main or console terminal.
*/
static u2_utty*
_term_main()
{
  u2_utty* uty_u;

  for ( uty_u = u2_Host.uty_u; uty_u; uty_u = uty_u->nex_u ) {
    if ( (uty_u->fid_i != -1) && (uty_u->fid_i <= 2) ) {
      return uty_u;
    }
  }
  return u2_Host.uty_u;
}

/* _term_ef_get(): terminal by id.
*/
static u2_utty*
_term_ef_get(c3_l     tid_l)
{
  if ( 0 != tid_l ) {
    u2_utty* uty_u;

    for ( uty_u = u2_Host.uty_u; uty_u; uty_u = uty_u->nex_u ) {
      if ( tid_l == uty_u->tid_l ) {
        return uty_u;
      }
    }
  }
  return _term_main();
}

/* u2_term_get_blew(): return window size [columns rows].
*/
u2_noun
u2_term_get_blew(c3_l tid_l)
{
  u2_utty*       uty_u = _term_ef_get(tid_l);
  c3_l           col_l, row_l;

  struct winsize siz_u;
  if ( uty_u && (0 == ioctl(uty_u->fid_i, TIOCGWINSZ, &siz_u)) ) {
    col_l = siz_u.ws_col;
    row_l = siz_u.ws_row;
  } else {
    col_l = 80;
    row_l = 24;
  }

  if ( uty_u ) {
    uty_u->tat_u.siz.col_l = col_l;
    uty_u->tat_u.siz.row_l = row_l;
  }

  return u2nc(col_l, row_l);
}

/* u2_term_ef_winc(): window change.  Just console right now.
*/
void
u2_term_ef_winc(void)
{
  u2_noun pax = u2nq(c3__gold, c3__term, '1', u2_nul);

  u2_reck_plan(u2A, pax, u2nc(c3__blew, u2_term_get_blew(1)));
}

/* u2_term_ef_ctlc(): send ^C on console.
*/
void
u2_term_ef_ctlc(void)
{
  u2_noun pax = u2nq(c3__gold, c3__term, '1', u2_nul);

  u2_reck_plan(u2A, pax, u2nt(c3__belt, c3__ctl, 'c'));
}

/* u2_term_ef_boil(): initial effects for loaded servers.
*/
void
u2_term_ef_boil(c3_l ono_l)
{
  if ( ono_l ) {
    u2_noun tid_l;

    for ( tid_l = 2; tid_l <= ono_l; tid_l++ ) {
      u2_noun tin = u2_dc("scot", c3__ud, tid_l);
      u2_noun pax = u2nq(c3__gold, c3__term, tin, u2_nul);
      u2_noun hud = u2nc(c3__wipe, u2_nul);

      u2_reck_plan(u2A, pax, hud);
    }
  }

  {
    u2_noun pax = u2nq(c3__gold, c3__term, '1', u2_nul);

    //  u2_reck_plan(u2A, u2k(pax), u2nc(c3__init, u2k(u2h(u2A->own))));
    u2_reck_plan(u2A, u2k(pax), u2nc(c3__blew, u2_term_get_blew(1)));
    u2_reck_plan(u2A, u2k(pax), u2nc(c3__hail, u2_nul));

    u2z(pax);
  }
}

/* u2_term_ef_bake(): initial effects for new terminal.
*/
void
u2_term_ef_bake(u2_noun  fav)
{
  u2_noun pax = u2nq(c3__gold, c3__term, '1', u2_nul);

  u2_reck_plan(u2A, u2k(pax), u2nc(c3__boot, fav));
  u2_reck_plan(u2A, u2k(pax), u2nc(c3__blew, u2_term_get_blew(1)));
  u2_reck_plan(u2A, u2k(pax), u2nc(c3__hail, u2_nul));

  u2z(pax);
}

/* _term_ef_blit(): send blit to terminal.
*/
static void
_term_ef_blit(u2_utty* uty_u,
              u2_noun  blt)
{
  switch ( u2h(blt) ) {
    default: break;
    case c3__bel: {
      if ( u2_no == u2_Host.ops_u.dem ) {
        _term_it_write_txt(uty_u, uty_u->ufo_u.out.bel_y);
      }
    } break;

    case c3__clr: {
      if ( u2_no == u2_Host.ops_u.dem ) {
        _term_it_show_blank(uty_u);
        _term_it_refresh_line(uty_u);
      }
    } break;

    case c3__hop: {
      if ( u2_no == u2_Host.ops_u.dem ) {
        _term_it_show_cursor(uty_u, u2t(blt));
      }
    } break;

    case c3__lin: {
      u2_noun lin = u2t(blt);
      c3_w    len_w = u2_ckb_lent(u2k(lin));
      c3_w*   lin_w = c3_malloc(4 * len_w);

      {
        c3_w i_w;

        for ( i_w = 0; u2_nul != lin; i_w++, lin = u2t(lin) ) {
          lin_w[i_w] = u2_cr_word(0, u2h(lin));
        }
      }

      if ( u2_no == u2_Host.ops_u.dem ) {
        _term_it_show_clear(uty_u);
        _term_it_show_line(uty_u, lin_w, len_w);
      } else {
        _term_it_show_line(uty_u, lin_w, len_w);
      }
    } break;

    case c3__mor: {
      _term_it_show_more(uty_u);
    } break;

    case c3__sav: {
      _term_it_save(u2k(u2h(u2t(blt))), u2k(u2t(u2t(blt))));
    } break;
  }
  u2z(blt);

  return;
}

/* u2_term_ef_blit(): send %blit list to specific terminal.
*/
void
u2_term_ef_blit(c3_l     tid_l,
                u2_noun  bls)
{
  u2_utty* uty_u = _term_ef_get(tid_l);

  if ( 0 == uty_u ) {
    // uL(fprintf(uH, "no terminal %d\n", tid_l));
    // uL(fprintf(uH, "uty_u %p\n", u2_Host.uty_u));

    u2z(bls); return;
  }

  {
    u2_noun bis = bls;

    while ( u2_yes == u2du(bis) ) {
      _term_ef_blit(uty_u, u2k(u2h(bis)));
      bis = u2t(bis);
    }
    u2z(bls);
  }
}

/* u2_term_io_hija(): hijack console for fprintf, returning FILE*.
*/
FILE*
u2_term_io_hija(void)
{
  u2_utty* uty_u = _term_main();

  if ( uty_u ) {
    if ( uty_u->fid_i > 2 ) {
      //  We *should* in fact, produce some kind of fake FILE* for
      //  non-console terminals.  If we use this interface enough...
      //
      c3_assert(0);
    }
    else {
      if ( u2_no == u2_Host.ops_u.dem ) {
        if ( 0 != tcsetattr(1, TCSADRAIN, &uty_u->bak_u) ) {
          c3_assert(!"hija-tcsetattr");
        }
        if ( -1 == fcntl(1, F_SETFL, uty_u->cug_i) ) {
          c3_assert(!"hija-fcntl");
        }
        if ( 0 != tcsetattr(0, TCSADRAIN, &uty_u->bak_u) ) {
          c3_assert(!"hija-tcsetattr");
        }
        if ( -1 == fcntl(0, F_SETFL, uty_u->cug_i) ) {
          c3_assert(!"hija-fcntl");
        }
        write(uty_u->fid_i, "\r", 1);
        write(uty_u->fid_i, uty_u->ufo_u.out.el_y,
                            strlen((c3_c*) uty_u->ufo_u.out.el_y));
      }
      return stdout;
    }
  }
  else return stdout;
}

/* u2_term_io_loja(): release console from fprintf.
*/
void
u2_term_io_loja(int x)
{
  u2_utty* uty_u = _term_main();

  if ( uty_u ) {
    if ( uty_u->fid_i > 2 ) {
      //  We *should* in fact, produce some kind of fake FILE* for
      //  non-console terminals.  If we use this interface enough...
      //
      c3_assert(0);
    }
    else {
      if ( u2_yes == u2_Host.ops_u.dem ) {
        fflush(stdout);
      }
      else {
        if ( 0 != tcsetattr(1, TCSADRAIN, &uty_u->raw_u) ) {
          c3_assert(!"loja-tcsetattr");
        }
        if ( -1 == fcntl(1, F_SETFL, uty_u->nob_i) ) {
          c3_assert(!"loja-fcntl");
        }
        if ( 0 != tcsetattr(0, TCSADRAIN, &uty_u->raw_u) ) {
          c3_assert(!"loja-tcsetattr");
        }
        if ( -1 == fcntl(0, F_SETFL, uty_u->nob_i) ) {
          c3_assert(!"loja-fcntl");
        }
        _term_it_refresh_line(uty_u);
      }
    }
  }
}