fuNote/terminal.c

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <time.h>

#include "fn.h"
#include "terminal.h"

void die(const char *s) {
  write(STDOUT_FILENO, "\x1b[2J", 4);
  write(STDOUT_FILENO, "\x1b[H", 3);
  perror(s);
  exit(1);
}

void disableRawMode() {
  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &E.orig_termios) == -1)
    die("tcsetattr");
}

void enableRawMode() {
  if (tcgetattr(STDIN_FILENO, &E.orig_termios) == -1)
    die("tcgetattr");
  atexit(disableRawMode);

  struct termios raw = E.orig_termios;
  raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
  raw.c_oflag &= ~(OPOST);
  raw.c_cflag |= (CS8);
  raw.c_lflag &= ~(ECHO | ICANON | ISIG);
  raw.c_cc[VMIN] = 0;
  raw.c_cc[VTIME] = 1;

  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1)
    die("tcsetattr");
}

int editorReadKey() {
  int nread;
  char c;
  while ((nread = read(STDIN_FILENO, &c, 1)) != 1) {
    if (nread == -1 && errno != EAGAIN) die("read");
  }

  // Process escape sequences
  if (c == '\x1b') {
    char seq[3];

    if (read(STDIN_FILENO, &seq[0], 1) != 1) return '\x1b';
    if (read(STDIN_FILENO, &seq[1], 1) != 1) return '\x1b';

    if (seq[0] == '[') {
      if (seq[1] >= '0' && seq[1] <= '9') {
        if (read(STDIN_FILENO, &seq[2], 1) != 1) return '\x1b';
        if (seq[2] == '~') {
          switch (seq[1]) {
            case '1': return HOME_KEY;
            case '3': return DEL_KEY;
            case '4': return END_KEY;
            case '5': return PAGE_UP;
            case '6': return PAGE_DOWN;
            case '7': return HOME_KEY;
            case '8': return END_KEY;
          }
        }
      } else {
        switch (seq[1]) {
          case 'A': return ARROW_UP;
          case 'B': return ARROW_DOWN;
          case 'C': return ARROW_RIGHT;
          case 'D': return ARROW_LEFT;
        }
      }
    } else if (seq[0] == '0') {
      switch (seq[1]) {
        case 'H': return HOME_KEY;
        case 'F': return END_KEY;
      }
    }

    return '\x1b';
  } else {
    return c;
  }
}

int getCursorPosition(int *rows, int *cols) {
  char buf[32];
  unsigned int i = 0;

  if (write(STDOUT_FILENO, "\x1b[6n", 4) != 4) // CPR (custor position report)
    return -1;

  while (i < sizeof(buf) - 1) {
    if (read(STDIN_FILENO, &buf[i], 1) != 1) break;
    if (buf[i] == 'R') break;
    i++;
  }
  buf[i] = '\0';

  if (buf[0] != '\x1b' || buf[1] != '[') return -1;
  if (sscanf(&buf[2], "%d;%d", rows, cols) != 2) return -1;

  return 0;
}

int setWindowSize(int *rows, int *cols) {
  struct winsize ws;

  if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1 || ws.ws_col == 0) {
    // Move cursor to the lower right as a fallback if TIOCGWINSZ does
    // not work. We count the columns and rows then by hand.
    if (write(STDOUT_FILENO, "\x1b[999C\x1b[999B", 12) != 12)
      return -1;
    return getCursorPosition(rows, cols);
    return -1;
  } else {
    *cols = ws.ws_col;
    *rows = ws.ws_row;
    return 0;
  }
}