1/*
2 * MinIO Go Library for Amazon S3 Compatible Cloud Storage
3 * Copyright 2015-2020 MinIO, Inc.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18package minio
19
20import (
21	"context"
22	"net/http"
23	"net/url"
24
25	"github.com/minio/minio-go/v7/pkg/s3utils"
26)
27
28// BucketExists verifies if bucket exists and you have permission to access it. Allows for a Context to
29// control cancellations and timeouts.
30func (c Client) BucketExists(ctx context.Context, bucketName string) (bool, error) {
31	// Input validation.
32	if err := s3utils.CheckValidBucketName(bucketName); err != nil {
33		return false, err
34	}
35
36	// Execute HEAD on bucketName.
37	resp, err := c.executeMethod(ctx, http.MethodHead, requestMetadata{
38		bucketName:       bucketName,
39		contentSHA256Hex: emptySHA256Hex,
40	})
41	defer closeResponse(resp)
42	if err != nil {
43		if ToErrorResponse(err).Code == "NoSuchBucket" {
44			return false, nil
45		}
46		return false, err
47	}
48	if resp != nil {
49		resperr := httpRespToErrorResponse(resp, bucketName, "")
50		if ToErrorResponse(resperr).Code == "NoSuchBucket" {
51			return false, nil
52		}
53		if resp.StatusCode != http.StatusOK {
54			return false, httpRespToErrorResponse(resp, bucketName, "")
55		}
56	}
57	return true, nil
58}
59
60// StatObject verifies if object exists and you have permission to access.
61func (c Client) StatObject(ctx context.Context, bucketName, objectName string, opts StatObjectOptions) (ObjectInfo, error) {
62	// Input validation.
63	if err := s3utils.CheckValidBucketName(bucketName); err != nil {
64		return ObjectInfo{}, err
65	}
66	if err := s3utils.CheckValidObjectName(objectName); err != nil {
67		return ObjectInfo{}, err
68	}
69	return c.statObject(ctx, bucketName, objectName, opts)
70}
71
72// Lower level API for statObject supporting pre-conditions and range headers.
73func (c Client) statObject(ctx context.Context, bucketName, objectName string, opts StatObjectOptions) (ObjectInfo, error) {
74	// Input validation.
75	if err := s3utils.CheckValidBucketName(bucketName); err != nil {
76		return ObjectInfo{}, err
77	}
78	if err := s3utils.CheckValidObjectName(objectName); err != nil {
79		return ObjectInfo{}, err
80	}
81	headers := opts.Header()
82	if opts.Internal.ReplicationDeleteMarker {
83		headers.Set(minIOBucketReplicationDeleteMarker, "true")
84	}
85
86	urlValues := make(url.Values)
87	if opts.VersionID != "" {
88		urlValues.Set("versionId", opts.VersionID)
89	}
90	// Execute HEAD on objectName.
91	resp, err := c.executeMethod(ctx, http.MethodHead, requestMetadata{
92		bucketName:       bucketName,
93		objectName:       objectName,
94		queryValues:      urlValues,
95		contentSHA256Hex: emptySHA256Hex,
96		customHeader:     headers,
97	})
98	defer closeResponse(resp)
99	if err != nil {
100		return ObjectInfo{}, err
101	}
102	deleteMarker := resp.Header.Get(amzDeleteMarker) == "true"
103
104	if resp != nil {
105		if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
106			if resp.StatusCode == http.StatusBadRequest && opts.VersionID != "" && deleteMarker {
107				errResp := ErrorResponse{
108					StatusCode: resp.StatusCode,
109					Code:       "MethodNotAllowed",
110					Message:    "The specified method is not allowed against this resource.",
111					BucketName: bucketName,
112					Key:        objectName,
113				}
114				return ObjectInfo{
115					VersionID:      resp.Header.Get(amzVersionID),
116					IsDeleteMarker: deleteMarker,
117				}, errResp
118			}
119			return ObjectInfo{
120				VersionID:      resp.Header.Get(amzVersionID),
121				IsDeleteMarker: deleteMarker,
122			}, httpRespToErrorResponse(resp, bucketName, objectName)
123		}
124	}
125
126	return ToObjectInfo(bucketName, objectName, resp.Header)
127}
128