busybox/console-tools/resize.c

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/* vi: set sw=4 ts=4: */
/*
* resize - set terminal width and height.
*
* Copyright 2006 Bernhard Fischer
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
/* no options, no getopt */
#include "libbb.h"
#define ESC "\033"
struct termios old;
static void
onintr(int sig ATTRIBUTE_UNUSED)
{
tcsetattr(STDERR_FILENO, TCSANOW, &old);
exit(1);
}
int resize_main(int argc, char **argv);
int resize_main(int argc, char **argv)
{
struct termios new;
struct winsize w = { 0,0,0,0 };
int ret;
/* We use _stderr_ in order to make resize usable
* in shell backticks (those redirect stdout away from tty).
* NB: other versions of resize open "/dev/tty"
* and operate on it - should we do the same?
*/
tcgetattr(STDERR_FILENO, &old); /* fiddle echo */
new = old;
new.c_cflag |= (CLOCAL | CREAD);
new.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
signal(SIGINT, onintr);
signal(SIGQUIT, onintr);
signal(SIGTERM, onintr);
signal(SIGALRM, onintr);
tcsetattr(STDERR_FILENO, TCSANOW, &new);
/* save_cursor_pos 7
* scroll_whole_screen [r
* put_cursor_waaaay_off [$x;$yH
* get_cursor_pos [6n
* restore_cursor_pos 8
*/
fprintf(stderr, ESC"7" ESC"[r" ESC"[999;999H" ESC"[6n");
alarm(3); /* Just in case terminal won't answer */
scanf(ESC"[%hu;%huR", &w.ws_row, &w.ws_col);
fprintf(stderr, ESC"8");
/* BTW, other versions of resize recalculate w.ws_xpixel, ws.ws_ypixel
* by calculating character cell HxW from old values
* (gotten via TIOCGWINSZ) and recomputing *pixel values */
ret = ioctl(STDERR_FILENO, TIOCSWINSZ, &w);
tcsetattr(STDERR_FILENO, TCSANOW, &old);
if (ENABLE_FEATURE_RESIZE_PRINT)
printf("COLUMNS=%d;LINES=%d;export COLUMNS LINES;\n",
w.ws_col, w.ws_row);
return ret;
}