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package helper
import (
"errors"
"io"
"strings"
)
var (
ErrContainsNull = errors.New("argument contains null character")
)
type argsWt []string
// checks whether any element contains the null character
// must be called before args use and args must not be modified after call
func (a argsWt) check() error {
for _, arg := range a {
for _, b := range arg {
if b == '\x00' {
return ErrContainsNull
}
}
}
return nil
}
func (a argsWt) WriteTo(w io.Writer) (int64, error) {
// assuming already checked
nt := 0
// write null terminated arguments
for _, arg := range a {
n, err := w.Write([]byte(arg + "\x00"))
nt += n
if err != nil {
return int64(nt), err
}
}
return int64(nt), nil
}
func (a argsWt) String() string {
return strings.Join(a, " ")
}
// NewCheckedArgs returns a checked argument writer for args.
// Callers must not retain any references to args.
func NewCheckedArgs(args []string) (io.WriterTo, error) {
a := argsWt(args)
return a, a.check()
}
// MustNewCheckedArgs returns a checked argument writer for args and panics if check fails.
// Callers must not retain any references to args.
func MustNewCheckedArgs(args []string) io.WriterTo {
a, err := NewCheckedArgs(args)
if err != nil {
panic(err.Error())
}
return a
}
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