cmd/prognosis/term_unix.go


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//go:build linux || darwin || freebsd || netbsd || openbsd

package main

import (
	"os"
	"syscall"
	"unsafe"
)

// termCols asks the terminal for its width.
//
// This is an ioctl rather than golang.org/x/term because the spec keeps this
// binary free of third-party modules; it is a dozen lines and only needs to
// work on the platforms prognosis is built for.
func termCols() (int, bool) {
	var ws struct{ Row, Col, Xpixel, Ypixel uint16 }
	_, _, errno := syscall.Syscall(
		syscall.SYS_IOCTL,
		os.Stdout.Fd(),
		uintptr(syscall.TIOCGWINSZ),
		uintptr(unsafe.Pointer(&ws)),
	)
	if errno != 0 || ws.Col == 0 {
		return 0, false
	}
	return int(ws.Col), true
}