github.com/meulengracht/snapd@v0.0.0-20210719210640-8bde69bcc84e/osutil/winsize.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2014-2015 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package osutil
    21  
    22  import (
    23  	"syscall"
    24  	"unsafe"
    25  )
    26  
    27  // Winsize is from tty_ioctl(4)
    28  type Winsize struct {
    29  	Row    uint16
    30  	Col    uint16
    31  	xpixel uint16 // unused
    32  	Ypixel uint16 // unused
    33  }
    34  
    35  // GetTermWinsize performs the TIOCGWINSZ ioctl on stdout
    36  func GetTermWinsize() (*Winsize, error) {
    37  	ws := &Winsize{}
    38  	x, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(syscall.Stdout), uintptr(syscall.TIOCGWINSZ), uintptr(unsafe.Pointer(ws)))
    39  
    40  	if int(x) == -1 {
    41  		// returning ws on error lets people that don't care
    42  		// about the error get on with querying the struct
    43  		// (which will be empty on error).
    44  		return ws, errno
    45  	}
    46  
    47  	return ws, nil
    48  }