/* Query terminal dimensions.

   Requires stderr to not be redirected.
                                         */

#include<sys/ioctl.h>
#include<stdio.h>
#include<string.h>
#include<unistd.h>

int main(int argc, char **argv)
{
   struct winsize ww;

   if( argc != 2 )
      return printf("%s <ws_row|ws_col|ws_xpixel|ws_ypixel>\n", *argv);

   /* Ask for the window size of stderr, and not stdout.
      We do this because stdout is going to be consumed by the script
      calling this utility, while stderr will remain connected to the
      real terminal.
                                                                      */
   ioctl(STDERR_FILENO, TIOCGWINSZ, &ww);
   #define OUTPUT_FIELD(field)               \
      if( strcmp(argv[1], #field) == 0 )     \
      {                                      \
         printf("%d\n", (int)(ww.field));    \
      }                                      \
      else

   OUTPUT_FIELD(ws_row)
   OUTPUT_FIELD(ws_col)
   OUTPUT_FIELD(ws_xpixel)
   OUTPUT_FIELD(ws_ypixel)
   {
      printf("Unrecognized field: %s\n", argv[1]);
      return 1;
   }
   return 0;
}