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package smtp
import (
"errors"
"io"
)
var ErrTooLongLine = errors.New("smtp: too long a line in input stream")
// lineLimitReader reads from the underlying Reader but restricts
// line length of lines in input stream to a certain length.
//
// If line length exceeds the limit - Read returns ErrTooLongLine
type lineLimitReader struct {
R io.Reader
LineLimit int
curLineLength int
}
func (r *lineLimitReader) Read(b []byte) (int, error) {
if r.curLineLength > r.LineLimit && r.LineLimit > 0 {
return 0, ErrTooLongLine
}
n, err := r.R.Read(b)
if err != nil {
return n, err
}
if r.LineLimit == 0 {
return n, nil
}
for _, chr := range b[:n] {
if chr == '\n' {
r.curLineLength = 0
}
r.curLineLength++
if r.curLineLength > r.LineLimit {
return 0, ErrTooLongLine
}
}
return n, nil
}
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