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vendor/github.com/minio/minio-go/api-stat.go

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+/*
+ * Minio Go Library for Amazon S3 Compatible Cloud Storage
+ * Copyright 2015-2017 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 minio
+
+import (
+	"context"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/minio/minio-go/pkg/s3utils"
+)
+
+// BucketExists verify if bucket exists and you have permission to access it.
+func (c Client) BucketExists(bucketName string) (bool, error) {
+	// Input validation.
+	if err := s3utils.CheckValidBucketName(bucketName); err != nil {
+		return false, err
+	}
+
+	// Execute HEAD on bucketName.
+	resp, err := c.executeMethod(context.Background(), "HEAD", requestMetadata{
+		bucketName:       bucketName,
+		contentSHA256Hex: emptySHA256Hex,
+	})
+	defer closeResponse(resp)
+	if err != nil {
+		if ToErrorResponse(err).Code == "NoSuchBucket" {
+			return false, nil
+		}
+		return false, err
+	}
+	if resp != nil {
+		if resp.StatusCode != http.StatusOK {
+			return false, httpRespToErrorResponse(resp, bucketName, "")
+		}
+	}
+	return true, nil
+}
+
+// List of header keys to be filtered, usually
+// from all S3 API http responses.
+var defaultFilterKeys = []string{
+	"Connection",
+	"Transfer-Encoding",
+	"Accept-Ranges",
+	"Date",
+	"Server",
+	"Vary",
+	"x-amz-bucket-region",
+	"x-amz-request-id",
+	"x-amz-id-2",
+	"Content-Security-Policy",
+	"X-Xss-Protection",
+
+	// Add new headers to be ignored.
+}
+
+// Extract only necessary metadata header key/values by
+// filtering them out with a list of custom header keys.
+func extractObjMetadata(header http.Header) http.Header {
+	filterKeys := append([]string{
+		"ETag",
+		"Content-Length",
+		"Last-Modified",
+		"Content-Type",
+	}, defaultFilterKeys...)
+	return filterHeader(header, filterKeys)
+}
+
+// StatObject verifies if object exists and you have permission to access.
+func (c Client) StatObject(bucketName, objectName string, opts StatObjectOptions) (ObjectInfo, error) {
+	// Input validation.
+	if err := s3utils.CheckValidBucketName(bucketName); err != nil {
+		return ObjectInfo{}, err
+	}
+	if err := s3utils.CheckValidObjectName(objectName); err != nil {
+		return ObjectInfo{}, err
+	}
+	return c.statObject(context.Background(), bucketName, objectName, opts)
+}
+
+// Lower level API for statObject supporting pre-conditions and range headers.
+func (c Client) statObject(ctx context.Context, bucketName, objectName string, opts StatObjectOptions) (ObjectInfo, error) {
+	// Input validation.
+	if err := s3utils.CheckValidBucketName(bucketName); err != nil {
+		return ObjectInfo{}, err
+	}
+	if err := s3utils.CheckValidObjectName(objectName); err != nil {
+		return ObjectInfo{}, err
+	}
+
+	// Execute HEAD on objectName.
+	resp, err := c.executeMethod(ctx, "HEAD", requestMetadata{
+		bucketName:       bucketName,
+		objectName:       objectName,
+		contentSHA256Hex: emptySHA256Hex,
+		customHeader:     opts.Header(),
+	})
+	defer closeResponse(resp)
+	if err != nil {
+		return ObjectInfo{}, err
+	}
+	if resp != nil {
+		if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
+			return ObjectInfo{}, httpRespToErrorResponse(resp, bucketName, objectName)
+		}
+	}
+
+	// Trim off the odd double quotes from ETag in the beginning and end.
+	md5sum := strings.TrimPrefix(resp.Header.Get("ETag"), "\"")
+	md5sum = strings.TrimSuffix(md5sum, "\"")
+
+	// Parse content length is exists
+	var size int64 = -1
+	contentLengthStr := resp.Header.Get("Content-Length")
+	if contentLengthStr != "" {
+		size, err = strconv.ParseInt(contentLengthStr, 10, 64)
+		if err != nil {
+			// Content-Length is not valid
+			return ObjectInfo{}, ErrorResponse{
+				Code:       "InternalError",
+				Message:    "Content-Length is invalid. " + reportIssue,
+				BucketName: bucketName,
+				Key:        objectName,
+				RequestID:  resp.Header.Get("x-amz-request-id"),
+				HostID:     resp.Header.Get("x-amz-id-2"),
+				Region:     resp.Header.Get("x-amz-bucket-region"),
+			}
+		}
+	}
+
+	// Parse Last-Modified has http time format.
+	date, err := time.Parse(http.TimeFormat, resp.Header.Get("Last-Modified"))
+	if err != nil {
+		return ObjectInfo{}, ErrorResponse{
+			Code:       "InternalError",
+			Message:    "Last-Modified time format is invalid. " + reportIssue,
+			BucketName: bucketName,
+			Key:        objectName,
+			RequestID:  resp.Header.Get("x-amz-request-id"),
+			HostID:     resp.Header.Get("x-amz-id-2"),
+			Region:     resp.Header.Get("x-amz-bucket-region"),
+		}
+	}
+
+	// Fetch content type if any present.
+	contentType := strings.TrimSpace(resp.Header.Get("Content-Type"))
+	if contentType == "" {
+		contentType = "application/octet-stream"
+	}
+
+	// Save object metadata info.
+	return ObjectInfo{
+		ETag:         md5sum,
+		Key:          objectName,
+		Size:         size,
+		LastModified: date,
+		ContentType:  contentType,
+		// Extract only the relevant header keys describing the object.
+		// following function filters out a list of standard set of keys
+		// which are not part of object metadata.
+		Metadata: extractObjMetadata(resp.Header),
+	}, nil
+}