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Merge pull request #123620 from benluddy/json-frame-reader-underlying-array-reuse

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Remove shared ref to underlying array of JSONFrameReader's Read arg.
This commit is contained in:
Kubernetes Prow Robot 2024-05-09 11:33:09 -07:00 committed by GitHub
commit 5cb71ec2e4
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2 changed files with 27 additions and 6 deletions
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18
staging/src/k8s.io/apimachinery/pkg/util/framer/framer.go
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@ -147,7 +147,6 @@ func (r *jsonFrameReader) Read(data []byte) (int, error) {
// RawMessage#Unmarshal appends to data - we reset the slice down to 0 and will either see
// data written to data, or be larger than data and a different array.
n := len(data)
m := json.RawMessage(data[:0])
if err := r.decoder.Decode(&m); err != nil {
return 0, err
@ -156,12 +155,19 @@ func (r *jsonFrameReader) Read(data []byte) (int, error) {
// If capacity of data is less than length of the message, decoder will allocate a new slice
// and set m to it, which means we need to copy the partial result back into data and preserve
// the remaining result for subsequent reads.
if len(m) > n {
//nolint:staticcheck // SA4006,SA4010 underlying array of data is modified here.
data = append(data[0:0], m[:n]...)
r.remaining = m[n:]
return n, io.ErrShortBuffer
if len(m) > cap(data) {
copy(data, m)
r.remaining = m[len(data):]
return len(data), io.ErrShortBuffer
}
if len(m) > len(data) {
// The bytes beyond len(data) were stored in data's underlying array, which we do
// not own after this function returns.
r.remaining = append([]byte(nil), m[len(data):]...)
return len(data), io.ErrShortBuffer
}
return len(m), nil
}

15
staging/src/k8s.io/apimachinery/pkg/util/framer/framer_test.go
View File

@ -18,6 +18,7 @@ package framer
import (
"bytes"
"errors"
"io"
"testing"
)
@ -173,3 +174,17 @@ func TestJSONFrameReaderShortBuffer(t *testing.T) {
t.Fatalf("unexpected: %v %d %q", err, n, buf)
}
}
func TestJSONFrameReaderShortBufferNoUnderlyingArrayReuse(t *testing.T) {
b := bytes.NewBufferString("{}")
r := NewJSONFramedReader(io.NopCloser(b))
buf := make([]byte, 1, 2) // cap(buf) > len(buf) && cap(buf) <= len("{}")
if n, err := r.Read(buf); !errors.Is(err, io.ErrShortBuffer) || n != 1 || string(buf[:n]) != "{" {
t.Fatalf("unexpected: %v %d %q", err, n, buf)
}
buf = append(buf, make([]byte, 1)...) // stomps the second byte of the backing array
if n, err := r.Read(buf[1:]); err != nil || n != 1 || string(buf[1:1+n]) != "}" {
t.Fatalf("unexpected: %v %d %q", err, n, buf)
}
}