Warning: this is an htmlized version!
The original is across this link,
and the conversion rules are here.
#include <lua.h>
#include <lauxlib.h>
#include <sys/ioctl.h>
#include <linux/kd.h>

#include <unistd.h>
#include <string.h>
#include <errno.h>
/* #include <fcntl.h>
 * #include <stdio.h>
 * (find-man "2 ioctl" "On success, zero is returned")
 * (find-man "4 console_ioctl" "  PIO_FONTX")
 * (find-node "(libc)Error Messages" "char * strerror (int ERRNUM)")
 */
/* (find-luafile "include/lua.h" "push functions (C -> stack)")
 * (find-lua50ref "Querying the Stack")
 * (find-lua50ref "Getting Values from the Stack")
 * (find-lua50file "src/lib/loadlib.c" "luaL_checkstring")
 * (find-lua50file "src/lib/")
 * (find-lua50file "include/")
 * (find-lua50file "include/lua.h")
 * (find-lua50file "include/lauxlib.h" "checkint")
 */

static int lua_piofontx(lua_State* L) {
  struct consolefontdesc cfd;
  int len;
  cfd.chardata = (char *) luaL_checklstring(L, 1, &len);
  cfd.charcount = luaL_checkint(L, 2);
  cfd.charheight = luaL_checkint(L, 3);
  if(ioctl(STDIN_FILENO, PIO_FONTX, &cfd)) {
    lua_pushstring(L, strerror(errno));
    return 1;
  }
  return 0;
}

LUALIB_API int piofontx_init(lua_State *L) {
  lua_register(L, "piofontx", lua_piofontx);
  return 0;
}

/* (eev "cd ~/vtutil4/; make clean; make piofontx.so")
 */