validtoml/vendor/gopkg.in/alecthomas/kingpin.v2/guesswidth_unix.go

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2018-01-08 01:30:28 +01:00
// +build !appengine,linux freebsd darwin dragonfly netbsd openbsd
package kingpin
import (
"io"
"os"
"strconv"
"syscall"
"unsafe"
)
func guessWidth(w io.Writer) int {
// check if COLUMNS env is set to comply with
// http://pubs.opengroup.org/onlinepubs/009604499/basedefs/xbd_chap08.html
colsStr := os.Getenv("COLUMNS")
if colsStr != "" {
if cols, err := strconv.Atoi(colsStr); err == nil {
return cols
}
}
if t, ok := w.(*os.File); ok {
fd := t.Fd()
var dimensions [4]uint16
if _, _, err := syscall.Syscall6(
syscall.SYS_IOCTL,
uintptr(fd),
uintptr(syscall.TIOCGWINSZ),
uintptr(unsafe.Pointer(&dimensions)),
0, 0, 0,
); err == 0 {
return int(dimensions[1])
}
}
return 80
}