fix: invalid multipart offset when compressed+encrypted. (#12340)

Fixes `testSSES3EncryptedGetObjectReadSeekFunctional` mint test.

```
{
  "args": {
    "bucketName": "minio-go-test-w53hbpat649nhvws",
    "objectName": "6mdswladz4vfpp2oit1pkn3qd11te5"
  },
  "duration": 7537,
  "error": "We encountered an internal error, please try again.: cause(The requested range \"bytes 251717932 -> -116384170 of 135333762\" is not satisfiable.)",
  "function": "GetObject(bucketName, objectName)",
  "message": "CopyN failed",
  "name": "minio-go: testSSES3EncryptedGetObjectReadSeekFunctional",
  "status": "FAIL"
}
```

Compressed files always start at the beginning of a part so no additional offset should be added.

cmd/encryption-v1.go

@@ -71,14 +71,14 @@ const (
 // isEncryptedMultipart returns true if the current object is
 // uploaded by the user using multipart mechanism:
 // initiate new multipart, upload part, complete upload
-func isEncryptedMultipart(objInfo ObjectInfo) bool {
-	if len(objInfo.Parts) == 0 {
+func (o *ObjectInfo) isEncryptedMultipart() bool {
+	if len(o.Parts) == 0 {
 		return false
 	}
-	if !crypto.IsMultiPart(objInfo.UserDefined) {
+	if !crypto.IsMultiPart(o.UserDefined) {
 		return false
 	}
-	for _, part := range objInfo.Parts {
+	for _, part := range o.Parts {
 		_, err := sio.DecryptedSize(uint64(part.Size))
 		if err != nil {
 			return false
@@ -87,7 +87,7 @@ func isEncryptedMultipart(objInfo ObjectInfo) bool {
 	// Further check if this object is uploaded using multipart mechanism
 	// by the user and it is not about Erasure internally splitting the
 	// object into parts in PutObject()
-	return !(objInfo.backendType == BackendErasure && len(objInfo.ETag) == 32)
+	return !(o.backendType == BackendErasure && len(o.ETag) == 32)
 }
 
 // ParseSSECopyCustomerRequest parses the SSE-C header fields of the provided request.
@@ -427,7 +427,7 @@ func DecryptBlocksRequestR(inputReader io.Reader, h http.Header, seqNumber uint3
 
 	bucket, object := oi.Bucket, oi.Name
 	// Single part case
-	if !isEncryptedMultipart(oi) {
+	if !oi.isEncryptedMultipart() {
 		var reader io.Reader
 		var err error
 		if copySource {
@@ -589,7 +589,7 @@ func (o *ObjectInfo) DecryptedSize() (int64, error) {
 	if _, ok := crypto.IsEncrypted(o.UserDefined); !ok {
 		return 0, errors.New("Cannot compute decrypted size of an unencrypted object")
 	}
-	if !isEncryptedMultipart(*o) {
+	if !o.isEncryptedMultipart() {
 		size, err := sio.DecryptedSize(uint64(o.Size))
 		if err != nil {
 			err = errObjectTampered // assign correct error type
@@ -732,7 +732,7 @@ func (o *ObjectInfo) GetDecryptedRange(rs *HTTPRangeSpec) (encOff, encLength, sk
 	// Assemble slice of (decrypted) part sizes in `sizes`
 	var sizes []int64
 	var decObjSize int64 // decrypted total object size
-	if isEncryptedMultipart(*o) {
+	if o.isEncryptedMultipart() {
 		sizes = make([]int64, len(o.Parts))
 		for i, part := range o.Parts {
 			var partSize uint64

cmd/object-api-errors.go

@@ -561,7 +561,7 @@ type InvalidRange struct {
 }
 
 func (e InvalidRange) Error() string {
-	return fmt.Sprintf("The requested range \"bytes %d-%d/%d\" is not satisfiable.", e.OffsetBegin, e.OffsetEnd, e.ResourceSize)
+	return fmt.Sprintf("The requested range \"bytes %d -> %d of %d\" is not satisfiable.", e.OffsetBegin, e.OffsetEnd, e.ResourceSize)
 }
 
 // ObjectTooLarge error returned when the size of the object > max object size allowed (5G) per request.

cmd/object-api-utils.go

@@ -543,11 +543,6 @@ func getCompressedOffsets(objectInfo ObjectInfo, offset int64) (compressedOffset
 		}
 	}
 
-	if isEncryptedMultipart(objectInfo) && firstPartIdx > 0 {
-		off, _, _, _, _, err := objectInfo.GetDecryptedRange(partNumberToRangeSpec(objectInfo, firstPartIdx))
-		logger.LogIf(context.Background(), err)
-		compressedOffset += off
-	}
 	return compressedOffset, offset - skipLength, firstPartIdx
 }
 
@@ -632,6 +627,7 @@ func NewGetObjectReader(rs *HTTPRangeSpec, oi ObjectInfo, opts ObjectOptions) (
 		if err != nil {
 			return nil, 0, 0, err
 		}
+
 		off, length = int64(0), oi.Size
 		decOff, decLength := int64(0), actualSize
 		if rs != nil {
@@ -639,8 +635,10 @@ func NewGetObjectReader(rs *HTTPRangeSpec, oi ObjectInfo, opts ObjectOptions) (
 			if err != nil {
 				return nil, 0, 0, err
 			}
+
 			// In case of range based queries on multiparts, the offset and length are reduced.
 			off, decOff, firstPart = getCompressedOffsets(oi, off)
+
 			decLength = length
 			length = oi.Size - off
 			// For negative length we read everything.