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// Package exlib contains common library code for the examples.
package exlib
import (
"encoding/binary"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"time"
)
var progname = filepath.Base(os.Args[0])
// Before set to 5 minutes; certificates will attempt to auto-update 5
// minutes before they expire.
var Before = 5 * time.Minute
// Err displays a formatting error message to standard error,
// appending the error string, and exits with the status code from
// `exit`, à la err(3).
func Err(exit int, err error, format string, a ...interface{}) {
format = fmt.Sprintf("[%s] %s", progname, format)
format += ": %v\n"
a = append(a, err)
fmt.Fprintf(os.Stderr, format, a...)
os.Exit(exit)
}
// Errx displays a formatted error message to standard error and exits
// with the status code from `exit`, à la errx(3).
func Errx(exit int, format string, a ...interface{}) {
format = fmt.Sprintf("[%s] %s", progname, format)
format += "\n"
fmt.Fprintf(os.Stderr, format, a...)
os.Exit(exit)
}
// Warn displays a formatted error message to standard output,
// appending the error string, à la warn(3).
func Warn(err error, format string, a ...interface{}) (int, error) {
format = fmt.Sprintf("[%s] %s", progname, format)
format += ": %v\n"
a = append(a, err)
return fmt.Fprintf(os.Stderr, format, a...)
}
// Unpack reads a message from an io.Reader.
func Unpack(r io.Reader) ([]byte, error) {
var bl [2]byte
_, err := io.ReadFull(r, bl[:])
if err != nil {
return nil, err
}
n := binary.LittleEndian.Uint16(bl[:])
buf := make([]byte, int(n))
_, err = io.ReadFull(r, buf)
return buf, err
}
const messageMax = 1 << 16
// Pack writes a message to an io.Writer.
func Pack(w io.Writer, buf []byte) error {
if len(buf) > messageMax {
return errors.New("message is too large")
}
var bl [2]byte
binary.LittleEndian.PutUint16(bl[:], uint16(len(buf)))
_, err := w.Write(bl[:])
if err != nil {
return err
}
_, err = w.Write(buf)
return err
}
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