txn2/kubefwd

package fwdhost

import (
    "fmt"
    "io"
    "log"
    "os"

    "github.com/txn2/txeh"
)

// BackupHostFile will write a backup of the pre-modified host file
// the users home directory, if it does already exist.
func BackupHostFile(hostFile *txeh.Hosts) (string, error) {
    homeDirLocation, err := os.UserHomeDir()
    if err != nil {
        return "", err
    }

    backupHostsPath := homeDirLocation + "/hosts.original"
    if _, err := os.Stat(backupHostsPath); os.IsNotExist(err) {
        from, err := os.Open(hostFile.WriteFilePath)
        if err != nil {
            return "", err
        }
        defer func() { _ = from.Close() }()

        to, err := os.OpenFile(backupHostsPath, os.O_RDWR|os.O_CREATE, 0644)
        if err != nil {
            log.Fatal(err)
        }
        defer func() { _ = to.Close() }()

        _, err = io.Copy(to, from)
        if err != nil {
            return "", err
        }
        return fmt.Sprintf("Backing up your original hosts file %s to %s\n", hostFile.WriteFilePath, backupHostsPath), nil
    }

    return fmt.Sprintf("Original hosts backup already exists at %s\n", backupHostsPath), nil
}