func Multipart(etags ...ETag) ETag {
	if len(etags) == 0 {
		return nil
	}

	var n int64
	h := md5.New()
	for _, etag := range etags {
		if !etag.IsMultipart() && !etag.IsEncrypted() {
			h.Write(etag)
			n++
		}
	}
	etag := append(h.Sum(nil), '-')
	return strconv.AppendInt(etag, n, 10)
}

// Set adds the ETag to the HTTP headers. It overwrites any
// existing ETag entry.
//

	// We must not use the http.Header().Set method here because some (broken)
	// clients expect the ETag header key to be literally "ETag" - not "Etag" (case-sensitive).
	// Therefore, we have to set the ETag directly as map entry.
	if objInfo.ETag != "" && !delete {
		w.Header()[xhttp.ETag] = []string{`"` + objInfo.ETag + `"`}
	}

	// Set the relevant version ID as part of the response header.

		if _, err := io.Copy(io.Discard, reader); err != nil {
			t.Fatalf("Test %d: read failed: %v", i, err)
		}
		if ETag := reader.ETag(); !Equal(ETag, test.ETag) {
			t.Fatalf("Test %d: ETag mismatch: got %q - want %q", i, ETag, test.ETag)
		}
	}
}

var multipartTests = []struct { // Test cases have been generated using AWS S3
	ETags     []ETag
	Multipart ETag
}{
	{

	// Complete multipart.
	parts := []CompletePart{
		{ETag: etag1, PartNumber: 1},
		{ETag: etag2, PartNumber: 2},
	}
	_, err = obj.CompleteMultipartUpload(context.Background(), bucket, object, uploadID, parts, ObjectOptions{})
	if err != nil {
		// Failed to complete multipart upload, abort.
		t.Fatalf("%s : %s", instanceType, err.Error())
	}

	for _, disk := range disks {
		tmpMetaDir := path.Join(disk, minioMetaTmpBucket)

	"context"
	"slices"
	"time"

	"github.com/minio/madmin-go/v3"
)

func commonETags(etags []string) (etag string, maxima int) {
	etagOccurrenceMap := make(map[string]int, len(etags))

	// Ignore the uuid sentinel and count the rest.
	for _, etag := range etags {
		if etag == "" {
			continue
		}
		etagOccurrenceMap[etag]++
	}

	maxima = 0 // Counter for remembering max occurrence of elements.
	latest := ""

		ETag:       "",
		ShouldFail: true, // ETag prefix is not a valid hex value
	},
	{
		ObjectKey:  [32]byte{},
		ObjectInfo: ObjectInfo{ETag: "16516b396f0f4d4f2a0e7177557bec4-1-2"},
		ETag:       "",
		ShouldFail: true, // ETag contains multiple: -
	},
}

func TestDecryptETag(t *testing.T) {
	for i, test := range decryptETagTests {

		}
		if _, err := strconv.ParseInt(object.ETag[i+1:], 10, 32); err != nil {
			return "", errObjectTampered
		}
		return object.ETag, nil
	}

	etag, err := hex.DecodeString(object.ETag)
	if err != nil {
		return "", err
	}
	etag, err = key.UnsealETag(etag)
	if err != nil {
		return "", err
	}
	return hex.EncodeToString(etag), nil
}

		{[]CompletePart{{ETag: "wrong-md5-hash-string"}}, "0deb8cb07527b4b2669c861cb9653607-1", ""},

		// Single CompletePart with valid MD5 hash string.
		{[]CompletePart{{ETag: "cf1f738a5924e645913c984e0fe3d708"}}, "10dc1617fbcf0bd0858048cb96e6bd77-1", ""},

		// Multiple CompletePart with valid MD5 hash string.

				PartNumber: part.PartNumber,
				GotETag:    part.ETag,
			}
			return oi, invp
		}
		expPart := currentFI.Parts[partIdx]

		// ensure that part ETag is canonicalized to strip off extraneous quotes
		part.ETag = canonicalizeETag(part.ETag)
		expETag := tryDecryptETag(objectEncryptionKey, expPart.ETag, kind == crypto.S3)
		if expETag != part.ETag {
			invp := InvalidPart{
				PartNumber: part.PartNumber,

func (r *Reader) ActualSize() int64 { return r.actualSize }

// ETag returns the ETag computed by an underlying etag.Tagger.
// If the underlying io.Reader does not implement etag.Tagger
// it returns nil.
func (r *Reader) ETag() etag.ETag {
	if t, ok := r.src.(etag.Tagger); ok {
		return t.ETag()
	}
	return nil
}

// MD5Current returns the MD5 checksum of the content