Struggling with ANSI escape code: https://en.wikipedia.org/wiki/ANSI_escape_code

esc.c

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <time.h>
#include <ctype.h>
#include <termios.h>
#include <unistd.h>

#define ESC "\x1b"
#define CSI "\x1b\x5b"
#define CSILEN 2

void out(const char* str) {
  printf("%s", str);
  fflush(stdout);
}

void outc(const char c) {
  printf("%c", c);
  fflush(stdout);
}

void outf(const char* fmt, ...) {
  va_list arg;
  va_start(arg, fmt);
  vprintf(fmt, arg);
  va_end(arg);
  fflush(stdout);
}

void escup(int n) {
  outf(CSI "%dA", n);
}

void escdown(int n) {
  outf(CSI "%dB", n);
}

void escright(int n) {
  outf(CSI "%dC", n);
}

void escleft(int n) {
  outf(CSI "%dD", n);
}

void escsave() {
  out(ESC "7");
}

void escrestore() {
  out(ESC "8");
}

size_t read_until(char *p, size_t size, int in_fd, char end) {
  size_t i = 0;
  char buf[1] = {0};
  while (i + 1 < size) {
    switch (read(in_fd, buf, 1)) {
    case -1: // TODO: handle error
    case 0:
      goto end;
    }
    p[i] = buf[0];
    i++;
    if (buf[0] == end) {
      break;
    }
  }
end:
  p[i] = '\0';
  return i + 1;
}

void sleep_msec(long msec) {
  struct timespec ts;
  ts.tv_sec = msec / 1000;
  ts.tv_nsec = (msec % 1000) * 1000 * 1000;
  nanosleep(&ts, NULL);
}

void get_cursor(int* x, int* y) {
  *x = *y = 0;
  outf(CSI "6n");
  char buf[32] = {0};
  read_until(buf, sizeof(buf), STDIN_FILENO, 'R');
  char *p = buf;
  p += CSILEN;
  while (*p != ';') {
    if (!isdigit(*p)) {
      goto error;
    }
    *x = *x * 10 + (*p - '0');
    p++;
  }
  p++;
  while (*p != 'R') {
    if (!isdigit(*p)) {
      goto error;
    }
    *y = *y * 10 + (*p - '0');
    p++;
  }
  return;
error:
  *x = *y = -1;
}

void demo_bars() {
  const int line = 3;
  for (int width = 1; width <= 80; width++) {
    escsave();
    for (int i = 0; i < line; i++) {
      if (width > 1) {
        escright(width - 1);
      }
      out("*\n");
    }
    escrestore();
    sleep_msec(30);
  }
  escdown(line);
}

void demo_get_cursor() {
  // https://stackoverflow.com/a/8101262/6321251
  struct termios ttystate, ttysave;
  tcgetattr(STDIN_FILENO, &ttystate);
  ttysave = ttystate;
  ttystate.c_lflag &= ~(ICANON | ECHO);
  ttystate.c_cc[VMIN] = 1;
  ttystate.c_cc[VTIME] = 0;
  tcsetattr(STDIN_FILENO, TCSANOW, &ttystate);

  out("あえいうえおあお");
  int x, y;
  get_cursor(&x, &y);

  tcsetattr(STDIN_FILENO, TCSANOW, &ttysave);

  // y should be 17
  outf("(%d, %d)\n", x, y);
}

int main(int argc, char const* argv[])
{
  // demo_bars();
  demo_get_cursor();
  return 0;
}

Memo

• https://en.wikipedia.org/wiki/ANSI_escape_code
• http://pubs.opengroup.org/onlinepubs/7908799/xbd/termios.html#tag_008_001_007
  • via https://stackoverflow.com/a/44097160/6321251

read(2) blocks even when non-canonical mode (min=1) on Vim's :terminal. it seems bug maybe vim-jp/issues#1140