api: Implement CopyObject s3 API, doing server side copy.

Fixes #1172

object-handlers.go

@@ -17,12 +17,15 @@
 package main
 
 import (
+	"io"
 	"net/http"
 	"net/url"
 	"strconv"
+	"strings"
 
-	"github.com/gorilla/mux"
+	mux "github.com/gorilla/mux"
 	"github.com/minio/minio/pkg/fs"
+	"github.com/minio/minio/pkg/probe"
 )
 
 const (
@@ -147,14 +150,141 @@ func (api storageAPI) HeadObjectHandler(w http.ResponseWriter, r *http.Request)
 	w.WriteHeader(http.StatusOK)
 }
 
+// CopyObjectHandler - Copy Object
+// ----------
+// This implementation of the PUT operation adds an object to a bucket
+// while reading the object from another source.
+func (api storageAPI) CopyObjectHandler(w http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	bucket := vars["bucket"]
+	object := vars["object"]
+
+	if isRequestRequiresACLCheck(r) {
+		writeErrorResponse(w, r, AccessDenied, r.URL.Path)
+		return
+	}
+
+	if !isSignV4ReqAuthenticated(api.Signature, r) {
+		writeErrorResponse(w, r, SignatureDoesNotMatch, r.URL.Path)
+		return
+	}
+
+	// TODO: Reject requests where body/payload is present, for now we
+	// don't even read it.
+
+	// objectSource
+	objectSource := r.Header.Get("X-Amz-Copy-Source")
+
+	// Skip the first element if it is '/', split the rest.
+	if strings.HasPrefix(objectSource, "/") {
+		objectSource = objectSource[1:]
+	}
+	splits := strings.SplitN(objectSource, "/", 2)
+
+	// Save sourceBucket and sourceObject extracted from url Path.
+	var sourceBucket, sourceObject string
+	if len(splits) == 2 {
+		sourceBucket = splits[0]
+		sourceObject = splits[1]
+	}
+	// If source object is empty, reply back error.
+	if sourceObject == "" {
+		writeErrorResponse(w, r, InvalidCopySource, r.URL.Path)
+		return
+	}
+
+	// Source and destination objects cannot be same, reply back error.
+	if sourceObject == object && sourceBucket == bucket {
+		writeErrorResponse(w, r, InvalidCopyDest, r.URL.Path)
+		return
+	}
+
+	metadata, err := api.Filesystem.GetObjectMetadata(sourceBucket, sourceObject)
+	if err != nil {
+		errorIf(err.Trace(), "GetObjectMetadata failed.", nil)
+		switch err.ToGoError().(type) {
+		case fs.BucketNameInvalid:
+			writeErrorResponse(w, r, InvalidBucketName, objectSource)
+		case fs.BucketNotFound:
+			writeErrorResponse(w, r, NoSuchBucket, objectSource)
+		case fs.ObjectNotFound:
+			writeErrorResponse(w, r, NoSuchKey, objectSource)
+		case fs.ObjectNameInvalid:
+			writeErrorResponse(w, r, NoSuchKey, objectSource)
+		default:
+			writeErrorResponse(w, r, InternalError, objectSource)
+		}
+		return
+	}
+
+	/// maximum Upload size for object in a single CopyObject operation.
+	if isMaxObjectSize(metadata.Size) {
+		writeErrorResponse(w, r, EntityTooLarge, objectSource)
+		return
+	}
+
+	// Initialize a pipe for data pipe line.
+	reader, writer := io.Pipe()
+
+	// Start writing in a routine.
+	go func() {
+		defer writer.Close()
+		if _, getErr := api.Filesystem.GetObject(writer, sourceBucket, sourceObject, 0, 0); getErr != nil {
+			writer.CloseWithError(probe.WrapError(getErr))
+			return
+		}
+	}()
+
+	// Verify md5sum.
+	expectedMD5Sum := metadata.MD5
+	// Size of object.
+	size := metadata.Size
+
+	// Create the object.
+	metadata, err = api.Filesystem.CreateObject(bucket, object, expectedMD5Sum, size, reader, nil)
+	if err != nil {
+		errorIf(err.Trace(), "CreateObject failed.", nil)
+		switch err.ToGoError().(type) {
+		case fs.RootPathFull:
+			writeErrorResponse(w, r, RootPathFull, r.URL.Path)
+		case fs.BucketNotFound:
+			writeErrorResponse(w, r, NoSuchBucket, r.URL.Path)
+		case fs.BucketNameInvalid:
+			writeErrorResponse(w, r, InvalidBucketName, r.URL.Path)
+		case fs.BadDigest:
+			writeErrorResponse(w, r, BadDigest, r.URL.Path)
+		case fs.IncompleteBody:
+			writeErrorResponse(w, r, IncompleteBody, r.URL.Path)
+		case fs.InvalidDigest:
+			writeErrorResponse(w, r, InvalidDigest, r.URL.Path)
+		case fs.ObjectExistsAsPrefix:
+			writeErrorResponse(w, r, ObjectExistsAsPrefix, r.URL.Path)
+		default:
+			writeErrorResponse(w, r, InternalError, r.URL.Path)
+		}
+		return
+	}
+	response := generateCopyObjectResponse(metadata.MD5, metadata.LastModified)
+	encodedSuccessResponse := encodeSuccessResponse(response)
+	// write headers
+	setCommonHeaders(w)
+	// write success response.
+	writeSuccessResponse(w, encodedSuccessResponse)
+}
+
 // PutObjectHandler - PUT Object
 // ----------
 // This implementation of the PUT operation adds an object to a bucket.
 func (api storageAPI) PutObjectHandler(w http.ResponseWriter, r *http.Request) {
-	var object, bucket string
+	// If the matching failed, it means that the X-Amz-Copy-Source was
+	// wrong, fail right here.
+	if _, ok := r.Header["X-Amz-Copy-Source"]; ok {
+		writeErrorResponse(w, r, InvalidCopySource, r.URL.Path)
+		return
+	}
 	vars := mux.Vars(r)
-	bucket = vars["bucket"]
-	object = vars["object"]
+	bucket := vars["bucket"]
+	object := vars["object"]
 
 	if isRequestRequiresACLCheck(r) {
 		if api.Filesystem.IsPrivateBucket(bucket) || api.Filesystem.IsReadOnlyBucket(bucket) {