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ioutil.go
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/
ioutil.go
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package keeper
import (
"bytes"
"compress/gzip"
"io"
"io/ioutil"
"github.com/konstellation/kn-sdk/x/wasm/internal/types"
)
// magic bytes to identify gzip.
// See https://www.ietf.org/rfc/rfc1952.txt
// and https://github.com/golang/go/blob/master/src/net/http/sniff.go#L186
var gzipIdent = []byte("\x1F\x8B\x08")
// uncompress returns gzip uncompressed content or given src when not gzip.
func uncompress(src []byte, limit uint64) ([]byte, error) {
switch n := uint64(len(src)); {
case n < 3:
return src, nil
case n > limit:
return nil, types.ErrLimit
}
if !bytes.Equal(gzipIdent, src[0:3]) {
return src, nil
}
zr, err := gzip.NewReader(bytes.NewReader(src))
if err != nil {
return nil, err
}
zr.Multistream(false)
defer zr.Close()
return ioutil.ReadAll(LimitReader(zr, int64(limit)))
}
// LimitReader returns a Reader that reads from r
// but stops with types.ErrLimit after n bytes.
// The underlying implementation is a *io.LimitedReader.
func LimitReader(r io.Reader, n int64) io.Reader {
return &LimitedReader{r: &io.LimitedReader{R: r, N: n}}
}
type LimitedReader struct {
r *io.LimitedReader
}
func (l *LimitedReader) Read(p []byte) (n int, err error) {
if l.r.N <= 0 {
return 0, types.ErrLimit
}
return l.r.Read(p)
}