ObjectLayer/GetObject: Should return the right error value. Fix done in FS and XL. (#2133)

fixes #2117

fs-v1.go

@@ -248,7 +248,7 @@ func (fs fsObjects) GetObject(bucket, object string, offset int64, length int64,
 	}
 	// Allocate a staging buffer.
 	buf := make([]byte, int(bufSize))
-	for totalLeft > 0 {
+	for {
 		// Figure out the right size for the buffer.
 		curLeft := bufSize
 		if totalLeft < bufSize {
@@ -282,6 +282,9 @@ func (fs fsObjects) GetObject(bucket, object string, offset int64, length int64,
 			err = er
 			break
 		}
+		if totalLeft == 0 {
+			break
+		}
 	}
 	// Returns any error.
 	return toObjectErr(err, bucket, object)

xl-v1-object.go

@@ -67,6 +67,11 @@ func (xl xlObjects) GetObject(bucket, object string, startOffset int64, length i
 		return toObjectErr(errXLReadQuorum, bucket, object)
 	}
 
+	// If all the disks returned error, we return error.
+	if err := reduceErrs(errs); err != nil {
+		return toObjectErr(err, bucket, object)
+	}
+
 	// List all online disks.
 	onlineDisks, highestVersion, err := xl.listOnlineDisks(metaArr, errs)
 	if err != nil {

xl-v1-utils.go

@@ -23,6 +23,59 @@ import (
 	"path"
 )
 
+// Returns nil even if one of the slice elements is nil.
+// Else returns the error which occours the most.
+func reduceErrs(errs []error) error {
+	// In case the error type is not in the known error list.
+	var unknownErr = errors.New("unknown error")
+	var errTypes = []struct {
+		err   error // error type
+		count int   // occurance count
+	}{
+		// List of known error types. Any new type that can be returned from StorageAPI should
+		// be added to this list. Most common errors are listed here.
+		{errDiskNotFound, 0}, {errFaultyDisk, 0}, {errFileAccessDenied, 0},
+		{errFileNotFound, 0}, {errFileNameTooLong, 0}, {errVolumeNotFound, 0},
+		{errDiskFull, 0},
+		// unknownErr count - count of the number of unknown errors.
+		{unknownErr, 0},
+	}
+	// In case unknownErr count occours maximum number of times, unknownErrType is used to
+	// to store it so that it can be used for the return error type.
+	var unknownErrType error
+
+	// For each err in []errs increment the corresponding count value.
+	for _, err := range errs {
+		if err == nil {
+			// Return nil even if one of the elements is nil.
+			return nil
+		}
+		for i := range errTypes {
+			if errTypes[i].err == err {
+				errTypes[i].count++
+				break
+			}
+			if errTypes[i].err == unknownErr {
+				errTypes[i].count++
+				unknownErrType = err
+				break
+			}
+		}
+	}
+	max := 0
+	// Get the error type which has the maximum count.
+	for i, errType := range errTypes {
+		if errType.count > errTypes[max].count {
+			max = i
+		}
+	}
+	if errTypes[max].err == unknownErr {
+		// Return the unknown error.
+		return unknownErrType
+	}
+	return errTypes[max].err
+}
+
 // Validates if we have quorum based on the errors with errDiskNotFound.
 func isQuorum(errs []error, minQuorumCount int) bool {
 	var diskFoundCount int

xl-v1-utils_test.go

@@ -0,0 +1,43 @@
+/*
+ * Minio Cloud Storage, (C) 2015, 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package main
+
+import "testing"
+import "syscall"
+
+// Test for reduceErrs.
+func TestReduceErrs(t *testing.T) {
+	testCases := []struct {
+		errs []error
+		err  error
+	}{
+		{[]error{errDiskNotFound, errDiskNotFound, errDiskFull}, errDiskNotFound},
+		{[]error{errDiskNotFound, errDiskFull, errDiskFull}, errDiskFull},
+		{[]error{errDiskFull, errDiskNotFound, errDiskFull}, errDiskFull},
+		// A case for error not in the known errors list (refer to func reduceErrs)
+		{[]error{errDiskFull, syscall.EEXIST, syscall.EEXIST}, syscall.EEXIST},
+		{[]error{errDiskNotFound, errDiskNotFound, nil}, nil},
+		{[]error{nil, nil, nil}, nil},
+	}
+	for i, testCase := range testCases {
+		expected := testCase.err
+		got := reduceErrs(testCase.errs)
+		if expected != got {
+			t.Errorf("Test %d : expected %s, got %s", i+1, expected, got)
+		}
+	}
+}