get rows and cols in a tty
diff --git a/util.go b/util.go
new file mode 100644
index 0000000..67c52d0
--- /dev/null
+++ b/util.go
@@ -0,0 +1,35 @@
+package pty
+
+import (
+ "os"
+ "syscall"
+ "unsafe"
+)
+
+// Getsize returns the number of rows (lines) and cols (positions
+// in each line) in terminal t.
+func Getsize(t *os.File) (rows, cols int, err error) {
+ var ws winsize
+ err = windowrect(&ws, t.Fd())
+ return int(ws.ws_row), int(ws.ws_col), err
+}
+
+type winsize struct {
+ ws_row uint16
+ ws_col uint16
+ ws_xpixel uint16
+ ws_ypixel uint16
+}
+
+func windowrect(ws *winsize, fd uintptr) error {
+ _, _, errno := syscall.Syscall(
+ syscall.SYS_IOCTL,
+ fd,
+ syscall.TIOCGWINSZ,
+ uintptr(unsafe.Pointer(ws)),
+ )
+ if errno != 0 {
+ return syscall.Errno(errno)
+ }
+ return nil
+}
