add function to retrieve terminal size (cols/rows)

src/term.c

@@ -20,6 +20,8 @@
 # include <string.h>
 # include <errno.h>
 # include <fcntl.h>
+# include <sys/ioctl.h>
+# include <unistd.h>
 #endif
 
 #ifdef _WIN32
@@ -736,6 +738,50 @@ static int lst_keypressed(lua_State *L) {
 #endif
 }
 
+/*-------------------------------------------------------------------------
+ * Retrieve terminal size
+ *-------------------------------------------------------------------------*/
+
+
+/***
+Get the size of the terminal window.
+@function termsize
+@treturn[1] int the number of columns
+@treturn[1] int the number of rows
+@treturn[2] nil
+@treturn[2] string error message
+*/
+static int lst_termsize(lua_State *L) {
+    int columns, rows;
+
+#ifdef _WIN32
+    CONSOLE_SCREEN_BUFFER_INFO csbi;
+    if (!GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi)) {
+        lua_pushnil(L);
+        lua_pushstring(L, "Failed to get terminal size.");
+        return 2;
+    }
+    columns = csbi.srWindow.Right - csbi.srWindow.Left + 1;
+    rows = csbi.srWindow.Bottom - csbi.srWindow.Top + 1;
+
+#else
+    struct winsize ws;
+    if (ioctl(1, TIOCGWINSZ, &ws) == -1) {
+        lua_pushnil(L);
+        lua_pushstring(L, "Failed to get terminal size.");
+        return 2;
+    }
+    columns = ws.ws_col;
+    rows = ws.ws_row;
+
+#endif
+    lua_pushinteger(L, columns);
+    lua_pushinteger(L, rows);
+    return 2;
+}
+
+
+
 /*-------------------------------------------------------------------------
  * Initializes module
  *-------------------------------------------------------------------------*/
@@ -750,6 +796,7 @@ static luaL_Reg func[] = {
     { "setnonblock", lst_setnonblock },
     { "readkey", lst_readkey },
     { "keypressed", lst_keypressed },
+    { "termsize", lst_termsize },
     { NULL, NULL }
 };