server: Move all the top level files into cmd folder. (#2490)

This change brings a change which was done for the 'mc'
package to allow for clean repo and have a cleaner
github drop in experience.

cmd/httprange.go

@@ -0,0 +1,134 @@
+/*
+ * 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 cmd
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+const (
+	byteRangePrefix = "bytes="
+)
+
+// Valid byte position regexp
+var validBytePos = regexp.MustCompile(`^[0-9]+$`)
+
+// HttpRange specifies the byte range to be sent to the client.
+type httpRange struct {
+	offsetBegin  int64
+	offsetEnd    int64
+	resourceSize int64
+}
+
+// String populate range stringer interface
+func (hrange httpRange) String() string {
+	return fmt.Sprintf("bytes %d-%d/%d", hrange.offsetBegin, hrange.offsetEnd, hrange.resourceSize)
+}
+
+// getlength - get length from the range.
+func (hrange httpRange) getLength() int64 {
+	return 1 + hrange.offsetEnd - hrange.offsetBegin
+}
+
+func parseRequestRange(rangeString string, resourceSize int64) (hrange *httpRange, err error) {
+	// Return error if given range string doesn't start with byte range prefix.
+	if !strings.HasPrefix(rangeString, byteRangePrefix) {
+		return nil, fmt.Errorf("'%s' does not start with '%s'", rangeString, byteRangePrefix)
+	}
+
+	// Trim byte range prefix.
+	byteRangeString := strings.TrimPrefix(rangeString, byteRangePrefix)
+
+	// Check if range string contains delimiter '-', else return error. eg. "bytes=8"
+	sepIndex := strings.Index(byteRangeString, "-")
+	if sepIndex == -1 {
+		return nil, fmt.Errorf("'%s' does not have a valid range value", rangeString)
+	}
+
+	offsetBeginString := byteRangeString[:sepIndex]
+	offsetBegin := int64(-1)
+	// Convert offsetBeginString only if its not empty.
+	if len(offsetBeginString) > 0 {
+		if !validBytePos.MatchString(offsetBeginString) {
+			return nil, fmt.Errorf("'%s' does not have a valid first byte position value", rangeString)
+		}
+
+		if offsetBegin, err = strconv.ParseInt(offsetBeginString, 10, 64); err != nil {
+			return nil, fmt.Errorf("'%s' does not have a valid first byte position value", rangeString)
+		}
+	}
+
+	offsetEndString := byteRangeString[sepIndex+1:]
+	offsetEnd := int64(-1)
+	// Convert offsetEndString only if its not empty.
+	if len(offsetEndString) > 0 {
+		if !validBytePos.MatchString(offsetEndString) {
+			return nil, fmt.Errorf("'%s' does not have a valid last byte position value", rangeString)
+		}
+
+		if offsetEnd, err = strconv.ParseInt(offsetEndString, 10, 64); err != nil {
+			return nil, fmt.Errorf("'%s' does not have a valid last byte position value", rangeString)
+		}
+	}
+
+	// rangeString contains first and last byte positions. eg. "bytes=2-5"
+	if offsetBegin > -1 && offsetEnd > -1 {
+		if offsetBegin > offsetEnd {
+			// Last byte position is not greater than first byte position. eg. "bytes=5-2"
+			return nil, fmt.Errorf("'%s' does not have valid range value", rangeString)
+		}
+
+		// First and last byte positions should not be >= resourceSize.
+		if offsetBegin >= resourceSize {
+			return nil, errInvalidRange
+		}
+
+		if offsetEnd >= resourceSize {
+			offsetEnd = resourceSize - 1
+		}
+	} else if offsetBegin > -1 {
+		// rangeString contains only first byte position. eg. "bytes=8-"
+		if offsetBegin >= resourceSize {
+			// First byte position should not be >= resourceSize.
+			return nil, errInvalidRange
+		}
+
+		offsetEnd = resourceSize - 1
+	} else if offsetEnd > -1 {
+		// rangeString contains only last byte position. eg. "bytes=-3"
+		if offsetEnd == 0 {
+			// Last byte position should not be zero eg. "bytes=-0"
+			return nil, errInvalidRange
+		}
+
+		if offsetEnd >= resourceSize {
+			offsetBegin = 0
+		} else {
+			offsetBegin = resourceSize - offsetEnd
+		}
+
+		offsetEnd = resourceSize - 1
+	} else {
+		// rangeString contains first and last byte positions missing. eg. "bytes=-"
+		return nil, fmt.Errorf("'%s' does not have valid range value", rangeString)
+	}
+
+	return &httpRange{offsetBegin, offsetEnd, resourceSize}, nil
+}