release/src/router/busybox/console-tools/resize.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * resize - set terminal width and height.
   4  *
   5  * Copyright 2006 Bernhard Reutner-Fischer
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9 /* no options, no getopt */
  10
  11 //usage:#define resize_trivial_usage
  12 //usage:       ""
  13 //usage:#define resize_full_usage "\n\n"
  14 //usage:       "Resize the screen"
  15
  16 #include "libbb.h"
  17
  18 #define ESC "\033"
  19
  20 #define old_termios_p ((struct termios*)&bb_common_bufsiz1)
  21
  22 static void
  23 onintr(int sig UNUSED_PARAM)
  24 {
  25         tcsetattr(STDERR_FILENO, TCSANOW, old_termios_p);
  26         _exit(EXIT_FAILURE);
  27 }
  28
  29 int resize_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  30 int resize_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
  31 {
  32         struct termios new;
  33         struct winsize w = { 0, 0, 0, 0 };
  34         int ret;
  35
  36         /* We use _stderr_ in order to make resize usable
  37          * in shell backticks (those redirect stdout away from tty).
  38          * NB: other versions of resize open "/dev/tty"
  39          * and operate on it - should we do the same?
  40          */
  41
  42         tcgetattr(STDERR_FILENO, old_termios_p); /* fiddle echo */
  43         memcpy(&new, old_termios_p, sizeof(new));
  44         new.c_cflag |= (CLOCAL | CREAD);
  45         new.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
  46         bb_signals(0
  47                 + (1 << SIGINT)
  48                 + (1 << SIGQUIT)
  49                 + (1 << SIGTERM)
  50                 + (1 << SIGALRM)
  51                 , onintr);
  52         tcsetattr(STDERR_FILENO, TCSANOW, &new);
  53
  54         /* save_cursor_pos 7
  55          * scroll_whole_screen [r
  56          * put_cursor_waaaay_off [$x;$yH
  57          * get_cursor_pos [6n
  58          * restore_cursor_pos 8
  59          */
  60         fprintf(stderr, ESC"7" ESC"[r" ESC"[999;999H" ESC"[6n");
  61         alarm(3); /* Just in case terminal won't answer */
  62 //BUG: death by signal won't restore termios
  63         scanf(ESC"[%hu;%huR", &w.ws_row, &w.ws_col);
  64         fprintf(stderr, ESC"8");
  65
  66         /* BTW, other versions of resize recalculate w.ws_xpixel, ws.ws_ypixel
  67          * by calculating character cell HxW from old values
  68          * (gotten via TIOCGWINSZ) and recomputing *pixel values */
  69         ret = ioctl(STDERR_FILENO, TIOCSWINSZ, &w);
  70
  71         tcsetattr(STDERR_FILENO, TCSANOW, old_termios_p);
  72
  73         if (ENABLE_FEATURE_RESIZE_PRINT)
  74                 printf("COLUMNS=%d;LINES=%d;export COLUMNS LINES;\n",
  75                         w.ws_col, w.ws_row);
  76
  77         return ret;
  78 }