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// Copyright 2013 Apcera Inc. All rights reserved.
package term
import (
"os"
)
// Size is the size of a terminal, expressed in character cells, as Lines and
// Columns. This might come from environment variables or OS-dependent
// resources.
type Size struct {
Lines int
Columns int
}
// GetSize will return the terminal window size.
//
// We prefer environ $LINES/$COLUMNS, then fall back to tty-held information.
// We do not support use of termcap/terminfo to derive default size information.
func GetSize() (*Size, error) {
envSize := GetEnvWindowSize()
if envSize != nil && envSize.Lines != 0 && envSize.Columns != 0 {
return envSize, nil
}
fh, err := os.Open("/dev/tty")
if err != nil {
// no tty, no point continuing; we only let the environ
// avoid an error in this case because if someone has faked
// up an environ with LINES/COLUMNS _both_ set, we should let
// them
return nil, err
}
size, err := GetTerminalWindowSize(fh)
if err != nil {
if envSize != nil {
return envSize, nil
}
return nil, err
}
if envSize == nil {
return size, err
}
if envSize.Lines == 0 {
envSize.Lines = size.Lines
}
if envSize.Columns == 0 {
envSize.Columns = size.Columns
}
return envSize, nil
}
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