Merge pull request #57000 from sel/master

Automatic merge from submit-queue (batch tested with PRs 57324, 56931, 57000, 57150, 56965). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Fix YAMLDecoder Read behaviour

**What this PR does / why we need it**:

Makes YAMLDecoder adhere to the Read contract by returning the number of bytes
read.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #56999

**Special notes for your reviewer**:

**Release note**:

```release-note
YAMLDecoder Read now returns the number of bytes read
```

staging/src/k8s.io/apimachinery/pkg/util/yaml/decoder.go

@@ -122,7 +122,7 @@ func (d *YAMLDecoder) Read(data []byte) (n int, err error) {
 	if left <= len(data) {
 		copy(data, d.remaining)
 		d.remaining = nil
-		return len(d.remaining), nil
+		return left, nil
 	}
 
 	// caller will need to reread

staging/src/k8s.io/apimachinery/pkg/util/yaml/decoder_test.go

@@ -22,12 +22,38 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"math/rand"
 	"reflect"
 	"strings"
 	"testing"
 )
 
+func TestYAMLDecoderReadBytesLength(t *testing.T) {
+	d := `---
+stuff: 1
+	test-foo: 1
+`
+	testCases := []struct {
+		bufLen    int
+		expectLen int
+		expectErr error
+	}{
+		{len(d), len(d), nil},
+		{len(d) + 10, len(d), nil},
+		{len(d) - 10, len(d) - 10, io.ErrShortBuffer},
+	}
+
+	for i, testCase := range testCases {
+		r := NewDocumentDecoder(ioutil.NopCloser(bytes.NewReader([]byte(d))))
+		b := make([]byte, testCase.bufLen)
+		n, err := r.Read(b)
+		if err != testCase.expectErr || n != testCase.expectLen {
+			t.Fatalf("%d: unexpected body: %d / %v", i, n, err)
+		}
+	}
+}
+
 func TestSplitYAMLDocument(t *testing.T) {
 	testCases := []struct {
 		input  string