resize: make it usable in in backticks; have a timeout (if display

doesn't respond to 'get cursor pos' ESC sequence...)

diff --git a/console-tools/resize.c b/console-tools/resize.c
index 40a1b4ee09c9b625915df31ddce9ee9f19d9aade..64f318c76ca38d90ebcd608c5e74b5d87212ed2c 100644 (file)
--- a/console-tools/resize.c
+++ b/console-tools/resize.c
@@ -11,31 +11,60 @@
 
 #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 old, new;
-       struct winsize w = {0,0,0,0};
+       struct termios new;
+       struct winsize w = { 0,0,0,0 };
        int ret;
 
-       tcgetattr(STDOUT_FILENO, &old); /* fiddle echo */
+       /* 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);
-       tcsetattr(STDOUT_FILENO, TCSANOW, &new);
+       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
         */
-       printf(ESC"7" ESC"[r" ESC"[999;999H" ESC"[6n");
+       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);
-       ret = ioctl(STDOUT_FILENO, TIOCSWINSZ, &w);
-       printf(ESC"8");
-       tcsetattr(STDOUT_FILENO, TCSANOW, &old);
+       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;
 }