validate storage class across pools when setting config (#11320)

```
mc admin config set alias/ storage_class standard=EC:3
```

should only succeed if parity ratio is valid for all
server pools, if not we should fail proactively.

This PR also needs to bring other changes now that
we need to cater for variadic drive counts per pool.

Bonus fixes also various bugs reproduced with

- GetObjectWithPartNumber()
- CopyObjectPartWithOffsets()
- CopyObjectWithMetadata()
- PutObjectPart,PutObject with truncated streams

cmd/object-handlers.go

@@ -408,11 +408,7 @@ func (api objectAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Req
 			}
 		}
 
-		if checkPreconditions(ctx, w, r, oi, opts) {
-			return true
-		}
-
-		return false
+		return checkPreconditions(ctx, w, r, oi, opts)
 	}
 
 	gr, err := getObjectNInfo(ctx, bucket, object, rs, r.Header, readLock, opts)
@@ -997,8 +993,8 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 	// No need to compress for remote etcd calls
 	// Pass the decompressed stream to such calls.
 	isDstCompressed := objectAPI.IsCompressionSupported() &&
-		isCompressible(r.Header, srcObject) &&
-		!isRemoteCopyRequired(ctx, srcBucket, dstBucket, objectAPI)
+		isCompressible(r.Header, dstObject) &&
+		!isRemoteCopyRequired(ctx, srcBucket, dstBucket, objectAPI) && !cpSrcDstSame
 	if isDstCompressed {
 		compressMetadata = make(map[string]string, 2)
 		// Preserving the compression metadata.
@@ -1008,14 +1004,11 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 		// avoid copying them in target object.
 		crypto.RemoveInternalEntries(srcInfo.UserDefined)
 
-		s2c := newS2CompressReader(gr)
+		s2c := newS2CompressReader(gr, actualSize)
 		defer s2c.Close()
 		reader = s2c
 		length = -1
 	} else {
-		// Remove the metadata for remote calls.
-		delete(srcInfo.UserDefined, ReservedMetadataPrefix+"compression")
-		delete(srcInfo.UserDefined, ReservedMetadataPrefix+"actual-size")
 		reader = gr
 	}
 
@@ -1215,7 +1208,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 	// if encryption is enabled we do not need explicit "REPLACE" metadata to
 	// be enabled as well - this is to allow for key-rotation.
 	if !isDirectiveReplace(r.Header.Get(xhttp.AmzMetadataDirective)) && !isDirectiveReplace(r.Header.Get(xhttp.AmzTagDirective)) &&
-		srcInfo.metadataOnly && !crypto.IsEncrypted(srcInfo.UserDefined) && srcOpts.VersionID == "" && !objectEncryption {
+		srcInfo.metadataOnly && srcOpts.VersionID == "" && !objectEncryption {
 		// If x-amz-metadata-directive is not set to REPLACE then we need
 		// to error out if source and destination are same.
 		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidCopyDest), r.URL, guessIsBrowserReq(r))
@@ -1243,6 +1236,9 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 			return
 		}
+		// Remove the metadata for remote calls.
+		delete(srcInfo.UserDefined, ReservedMetadataPrefix+"compression")
+		delete(srcInfo.UserDefined, ReservedMetadataPrefix+"actual-size")
 		opts := miniogo.PutObjectOptions{
 			UserMetadata:         srcInfo.UserDefined,
 			ServerSideEncryption: dstOpts.ServerSideEncryption,
@@ -1470,7 +1466,7 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 		}
 
 		// Set compression metrics.
-		s2c := newS2CompressReader(actualReader)
+		s2c := newS2CompressReader(actualReader, actualSize)
 		defer s2c.Close()
 		reader = s2c
 		size = -1   // Since compressed size is un-predictable.
@@ -1971,7 +1967,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 	_, isCompressed := mi.UserDefined[ReservedMetadataPrefix+"compression"]
 	// Compress only if the compression is enabled during initial multipart.
 	if isCompressed {
-		s2c := newS2CompressReader(gr)
+		s2c := newS2CompressReader(gr, actualPartSize)
 		defer s2c.Close()
 		reader = s2c
 		length = -1
@@ -2218,7 +2214,7 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 		}
 
 		// Set compression metrics.
-		s2c := newS2CompressReader(actualReader)
+		s2c := newS2CompressReader(actualReader, actualSize)
 		defer s2c.Close()
 		reader = s2c
 		size = -1   // Since compressed size is un-predictable.