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