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Diffstat (limited to 'vendor/cloud.google.com/go/storage/storage.go')
| -rw-r--r-- | vendor/cloud.google.com/go/storage/storage.go | 910 |
1 files changed, 910 insertions, 0 deletions
diff --git a/vendor/cloud.google.com/go/storage/storage.go b/vendor/cloud.google.com/go/storage/storage.go new file mode 100644 index 0000000..3707ea9 --- /dev/null +++ b/vendor/cloud.google.com/go/storage/storage.go @@ -0,0 +1,910 @@ +// Copyright 2014 Google Inc. All Rights Reserved. +// +// 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 storage + +import ( + "bytes" + "crypto" + "crypto/rand" + "crypto/rsa" + "crypto/sha256" + "crypto/x509" + "encoding/base64" + "encoding/pem" + "errors" + "fmt" + "io" + "io/ioutil" + "net/http" + "net/url" + "reflect" + "strconv" + "strings" + "time" + "unicode/utf8" + + "google.golang.org/api/iterator" + "google.golang.org/api/option" + "google.golang.org/api/transport" + + "golang.org/x/net/context" + "google.golang.org/api/googleapi" + raw "google.golang.org/api/storage/v1" +) + +var ( + ErrBucketNotExist = errors.New("storage: bucket doesn't exist") + ErrObjectNotExist = errors.New("storage: object doesn't exist") + + // Done is returned by iterators in this package when they have no more items. + Done = iterator.Done +) + +const userAgent = "gcloud-golang-storage/20151204" + +const ( + // ScopeFullControl grants permissions to manage your + // data and permissions in Google Cloud Storage. + ScopeFullControl = raw.DevstorageFullControlScope + + // ScopeReadOnly grants permissions to + // view your data in Google Cloud Storage. + ScopeReadOnly = raw.DevstorageReadOnlyScope + + // ScopeReadWrite grants permissions to manage your + // data in Google Cloud Storage. + ScopeReadWrite = raw.DevstorageReadWriteScope +) + +// AdminClient is a client type for performing admin operations on a project's +// buckets. +// +// Deprecated: Client has all of AdminClient's methods. +type AdminClient struct { + c *Client + projectID string +} + +// NewAdminClient creates a new AdminClient for a given project. +// +// Deprecated: use NewClient instead. +func NewAdminClient(ctx context.Context, projectID string, opts ...option.ClientOption) (*AdminClient, error) { + c, err := NewClient(ctx, opts...) + if err != nil { + return nil, err + } + return &AdminClient{ + c: c, + projectID: projectID, + }, nil +} + +// Close closes the AdminClient. +func (c *AdminClient) Close() error { + return c.c.Close() +} + +// Create creates a Bucket in the project. +// If attrs is nil the API defaults will be used. +// +// Deprecated: use BucketHandle.Create instead. +func (c *AdminClient) CreateBucket(ctx context.Context, bucketName string, attrs *BucketAttrs) error { + return c.c.Bucket(bucketName).Create(ctx, c.projectID, attrs) +} + +// Delete deletes a Bucket in the project. +// +// Deprecated: use BucketHandle.Delete instead. +func (c *AdminClient) DeleteBucket(ctx context.Context, bucketName string) error { + return c.c.Bucket(bucketName).Delete(ctx) +} + +// Client is a client for interacting with Google Cloud Storage. +// +// Clients should be reused instead of created as needed. +// The methods of Client are safe for concurrent use by multiple goroutines. +type Client struct { + hc *http.Client + raw *raw.Service +} + +// NewClient creates a new Google Cloud Storage client. +// The default scope is ScopeFullControl. To use a different scope, like ScopeReadOnly, use option.WithScopes. +func NewClient(ctx context.Context, opts ...option.ClientOption) (*Client, error) { + o := []option.ClientOption{ + option.WithScopes(ScopeFullControl), + option.WithUserAgent(userAgent), + } + opts = append(o, opts...) + hc, _, err := transport.NewHTTPClient(ctx, opts...) + if err != nil { + return nil, fmt.Errorf("dialing: %v", err) + } + rawService, err := raw.New(hc) + if err != nil { + return nil, fmt.Errorf("storage client: %v", err) + } + return &Client{ + hc: hc, + raw: rawService, + }, nil +} + +// Close closes the Client. +// +// Close need not be called at program exit. +func (c *Client) Close() error { + c.hc = nil + return nil +} + +// BucketHandle provides operations on a Google Cloud Storage bucket. +// Use Client.Bucket to get a handle. +type BucketHandle struct { + acl ACLHandle + defaultObjectACL ACLHandle + + c *Client + name string +} + +// Bucket returns a BucketHandle, which provides operations on the named bucket. +// This call does not perform any network operations. +// +// The supplied name must contain only lowercase letters, numbers, dashes, +// underscores, and dots. The full specification for valid bucket names can be +// found at: +// https://cloud.google.com/storage/docs/bucket-naming +func (c *Client) Bucket(name string) *BucketHandle { + return &BucketHandle{ + c: c, + name: name, + acl: ACLHandle{ + c: c, + bucket: name, + }, + defaultObjectACL: ACLHandle{ + c: c, + bucket: name, + isDefault: true, + }, + } +} + +// SignedURLOptions allows you to restrict the access to the signed URL. +type SignedURLOptions struct { + // GoogleAccessID represents the authorizer of the signed URL generation. + // It is typically the Google service account client email address from + // the Google Developers Console in the form of "xxx@developer.gserviceaccount.com". + // Required. + GoogleAccessID string + + // PrivateKey is the Google service account private key. It is obtainable + // from the Google Developers Console. + // At https://console.developers.google.com/project/<your-project-id>/apiui/credential, + // create a service account client ID or reuse one of your existing service account + // credentials. Click on the "Generate new P12 key" to generate and download + // a new private key. Once you download the P12 file, use the following command + // to convert it into a PEM file. + // + // $ openssl pkcs12 -in key.p12 -passin pass:notasecret -out key.pem -nodes + // + // Provide the contents of the PEM file as a byte slice. + // Exactly one of PrivateKey or SignBytes must be non-nil. + PrivateKey []byte + + // SignBytes is a function for implementing custom signing. + // If your application is running on Google App Engine, you can use appengine's internal signing function: + // ctx := appengine.NewContext(request) + // acc, _ := appengine.ServiceAccount(ctx) + // url, err := SignedURL("bucket", "object", &SignedURLOptions{ + // GoogleAccessID: acc, + // SignBytes: func(b []byte) ([]byte, error) { + // _, signedBytes, err := appengine.SignBytes(ctx, b) + // return signedBytes, err + // }, + // // etc. + // }) + // + // Exactly one of PrivateKey or SignBytes must be non-nil. + SignBytes func([]byte) ([]byte, error) + + // Method is the HTTP method to be used with the signed URL. + // Signed URLs can be used with GET, HEAD, PUT, and DELETE requests. + // Required. + Method string + + // Expires is the expiration time on the signed URL. It must be + // a datetime in the future. + // Required. + Expires time.Time + + // ContentType is the content type header the client must provide + // to use the generated signed URL. + // Optional. + ContentType string + + // Headers is a list of extention headers the client must provide + // in order to use the generated signed URL. + // Optional. + Headers []string + + // MD5 is the base64 encoded MD5 checksum of the file. + // If provided, the client should provide the exact value on the request + // header in order to use the signed URL. + // Optional. + MD5 []byte +} + +// SignedURL returns a URL for the specified object. Signed URLs allow +// the users access to a restricted resource for a limited time without having a +// Google account or signing in. For more information about the signed +// URLs, see https://cloud.google.com/storage/docs/accesscontrol#Signed-URLs. +func SignedURL(bucket, name string, opts *SignedURLOptions) (string, error) { + if opts == nil { + return "", errors.New("storage: missing required SignedURLOptions") + } + if opts.GoogleAccessID == "" { + return "", errors.New("storage: missing required GoogleAccessID") + } + if (opts.PrivateKey == nil) == (opts.SignBytes == nil) { + return "", errors.New("storage: exactly one of PrivateKey or SignedBytes must be set") + } + if opts.Method == "" { + return "", errors.New("storage: missing required method option") + } + if opts.Expires.IsZero() { + return "", errors.New("storage: missing required expires option") + } + + signBytes := opts.SignBytes + if opts.PrivateKey != nil { + key, err := parseKey(opts.PrivateKey) + if err != nil { + return "", err + } + signBytes = func(b []byte) ([]byte, error) { + sum := sha256.Sum256(b) + return rsa.SignPKCS1v15( + rand.Reader, + key, + crypto.SHA256, + sum[:], + ) + } + } else { + signBytes = opts.SignBytes + } + + u := &url.URL{ + Path: fmt.Sprintf("/%s/%s", bucket, name), + } + + buf := &bytes.Buffer{} + fmt.Fprintf(buf, "%s\n", opts.Method) + fmt.Fprintf(buf, "%s\n", opts.MD5) + fmt.Fprintf(buf, "%s\n", opts.ContentType) + fmt.Fprintf(buf, "%d\n", opts.Expires.Unix()) + fmt.Fprintf(buf, "%s", strings.Join(opts.Headers, "\n")) + fmt.Fprintf(buf, "%s", u.String()) + + b, err := signBytes(buf.Bytes()) + if err != nil { + return "", err + } + encoded := base64.StdEncoding.EncodeToString(b) + u.Scheme = "https" + u.Host = "storage.googleapis.com" + q := u.Query() + q.Set("GoogleAccessId", opts.GoogleAccessID) + q.Set("Expires", fmt.Sprintf("%d", opts.Expires.Unix())) + q.Set("Signature", string(encoded)) + u.RawQuery = q.Encode() + return u.String(), nil +} + +// ObjectHandle provides operations on an object in a Google Cloud Storage bucket. +// Use BucketHandle.Object to get a handle. +type ObjectHandle struct { + c *Client + bucket string + object string + + acl ACLHandle + conds []Condition +} + +// ACL provides access to the object's access control list. +// This controls who can read and write this object. +// This call does not perform any network operations. +func (o *ObjectHandle) ACL() *ACLHandle { + return &o.acl +} + +// WithConditions returns a copy of o using the provided conditions. +func (o *ObjectHandle) WithConditions(conds ...Condition) *ObjectHandle { + o2 := *o + o2.conds = conds + return &o2 +} + +// Attrs returns meta information about the object. +// ErrObjectNotExist will be returned if the object is not found. +func (o *ObjectHandle) Attrs(ctx context.Context) (*ObjectAttrs, error) { + if !utf8.ValidString(o.object) { + return nil, fmt.Errorf("storage: object name %q is not valid UTF-8", o.object) + } + call := o.c.raw.Objects.Get(o.bucket, o.object).Projection("full").Context(ctx) + if err := applyConds("Attrs", o.conds, call); err != nil { + return nil, err + } + obj, err := call.Do() + if e, ok := err.(*googleapi.Error); ok && e.Code == http.StatusNotFound { + return nil, ErrObjectNotExist + } + if err != nil { + return nil, err + } + return newObject(obj), nil +} + +// Update updates an object with the provided attributes. +// All zero-value attributes are ignored. +// ErrObjectNotExist will be returned if the object is not found. +func (o *ObjectHandle) Update(ctx context.Context, attrs ObjectAttrs) (*ObjectAttrs, error) { + if !utf8.ValidString(o.object) { + return nil, fmt.Errorf("storage: object name %q is not valid UTF-8", o.object) + } + call := o.c.raw.Objects.Patch(o.bucket, o.object, attrs.toRawObject(o.bucket)).Projection("full").Context(ctx) + if err := applyConds("Update", o.conds, call); err != nil { + return nil, err + } + obj, err := call.Do() + if e, ok := err.(*googleapi.Error); ok && e.Code == http.StatusNotFound { + return nil, ErrObjectNotExist + } + if err != nil { + return nil, err + } + return newObject(obj), nil +} + +// Delete deletes the single specified object. +func (o *ObjectHandle) Delete(ctx context.Context) error { + if !utf8.ValidString(o.object) { + return fmt.Errorf("storage: object name %q is not valid UTF-8", o.object) + } + call := o.c.raw.Objects.Delete(o.bucket, o.object).Context(ctx) + if err := applyConds("Delete", o.conds, call); err != nil { + return err + } + err := call.Do() + switch e := err.(type) { + case nil: + return nil + case *googleapi.Error: + if e.Code == http.StatusNotFound { + return ErrObjectNotExist + } + } + return err +} + +// CopyTo copies the object to the given dst. +// The copied object's attributes are overwritten by attrs if non-nil. +// +// Deprecated: use ObjectHandle.CopierFrom instead. +func (o *ObjectHandle) CopyTo(ctx context.Context, dst *ObjectHandle, attrs *ObjectAttrs) (*ObjectAttrs, error) { + c := dst.CopierFrom(o) + if attrs != nil { + c.ObjectAttrs = *attrs + } + return c.Run(ctx) +} + +// ComposeFrom concatenates the provided slice of source objects into a new +// object whose destination is the receiver. The provided attrs, if not nil, +// are used to set the attributes on the newly-created object. All source +// objects must reside within the same bucket as the destination. +// +// Deprecated: use ObjectHandle.ComposerFrom instead. +func (o *ObjectHandle) ComposeFrom(ctx context.Context, srcs []*ObjectHandle, attrs *ObjectAttrs) (*ObjectAttrs, error) { + c := o.ComposerFrom(srcs...) + if attrs != nil { + c.ObjectAttrs = *attrs + } + return c.Run(ctx) +} + +// NewReader creates a new Reader to read the contents of the +// object. +// ErrObjectNotExist will be returned if the object is not found. +// +// The caller must call Close on the returned Reader when done reading. +func (o *ObjectHandle) NewReader(ctx context.Context) (*Reader, error) { + return o.NewRangeReader(ctx, 0, -1) +} + +// NewRangeReader reads part of an object, reading at most length bytes +// starting at the given offset. If length is negative, the object is read +// until the end. +func (o *ObjectHandle) NewRangeReader(ctx context.Context, offset, length int64) (*Reader, error) { + if !utf8.ValidString(o.object) { + return nil, fmt.Errorf("storage: object name %q is not valid UTF-8", o.object) + } + if offset < 0 { + return nil, fmt.Errorf("storage: invalid offset %d < 0", offset) + } + u := &url.URL{ + Scheme: "https", + Host: "storage.googleapis.com", + Path: fmt.Sprintf("/%s/%s", o.bucket, o.object), + } + verb := "GET" + if length == 0 { + verb = "HEAD" + } + req, err := http.NewRequest(verb, u.String(), nil) + if err != nil { + return nil, err + } + if err := applyConds("NewReader", o.conds, objectsGetCall{req}); err != nil { + return nil, err + } + if length < 0 && offset > 0 { + req.Header.Set("Range", fmt.Sprintf("bytes=%d-", offset)) + } else if length > 0 { + req.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", offset, offset+length-1)) + } + res, err := o.c.hc.Do(req) + if err != nil { + return nil, err + } + if res.StatusCode == http.StatusNotFound { + res.Body.Close() + return nil, ErrObjectNotExist + } + if res.StatusCode < 200 || res.StatusCode > 299 { + body, _ := ioutil.ReadAll(res.Body) + res.Body.Close() + return nil, &googleapi.Error{ + Code: res.StatusCode, + Header: res.Header, + Body: string(body), + } + } + if offset > 0 && length != 0 && res.StatusCode != http.StatusPartialContent { + res.Body.Close() + return nil, errors.New("storage: partial request not satisfied") + } + + var size int64 // total size of object, even if a range was requested. + if res.StatusCode == http.StatusPartialContent { + cr := strings.TrimSpace(res.Header.Get("Content-Range")) + if !strings.HasPrefix(cr, "bytes ") || !strings.Contains(cr, "/") { + return nil, fmt.Errorf("storage: invalid Content-Range %q", cr) + } + size, err = strconv.ParseInt(cr[strings.LastIndex(cr, "/")+1:], 10, 64) + if err != nil { + return nil, fmt.Errorf("storage: invalid Content-Range %q", cr) + } + } else { + size = res.ContentLength + } + + remain := res.ContentLength + body := res.Body + if length == 0 { + remain = 0 + body.Close() + body = emptyBody + } + + return &Reader{ + body: body, + size: size, + remain: remain, + contentType: res.Header.Get("Content-Type"), + }, nil +} + +var emptyBody = ioutil.NopCloser(strings.NewReader("")) + +// NewWriter returns a storage Writer that writes to the GCS object +// associated with this ObjectHandle. +// +// A new object will be created unless an object with this name already exists. +// Otherwise any previous object with the same name will be replaced. +// The object will not be available (and any previous object will remain) +// until Close has been called. +// +// Attributes can be set on the object by modifying the returned Writer's +// ObjectAttrs field before the first call to Write. If no ContentType +// attribute is specified, the content type will be automatically sniffed +// using net/http.DetectContentType. +// +// It is the caller's responsibility to call Close when writing is done. +func (o *ObjectHandle) NewWriter(ctx context.Context) *Writer { + return &Writer{ + ctx: ctx, + o: o, + donec: make(chan struct{}), + ObjectAttrs: ObjectAttrs{Name: o.object}, + } +} + +// parseKey converts the binary contents of a private key file +// to an *rsa.PrivateKey. It detects whether the private key is in a +// PEM container or not. If so, it extracts the the private key +// from PEM container before conversion. It only supports PEM +// containers with no passphrase. +func parseKey(key []byte) (*rsa.PrivateKey, error) { + if block, _ := pem.Decode(key); block != nil { + key = block.Bytes + } + parsedKey, err := x509.ParsePKCS8PrivateKey(key) + if err != nil { + parsedKey, err = x509.ParsePKCS1PrivateKey(key) + if err != nil { + return nil, err + } + } + parsed, ok := parsedKey.(*rsa.PrivateKey) + if !ok { + return nil, errors.New("oauth2: private key is invalid") + } + return parsed, nil +} + +func toRawObjectACL(oldACL []ACLRule) []*raw.ObjectAccessControl { + var acl []*raw.ObjectAccessControl + if len(oldACL) > 0 { + acl = make([]*raw.ObjectAccessControl, len(oldACL)) + for i, rule := range oldACL { + acl[i] = &raw.ObjectAccessControl{ + Entity: string(rule.Entity), + Role: string(rule.Role), + } + } + } + return acl +} + +// toRawObject copies the editable attributes from o to the raw library's Object type. +func (o ObjectAttrs) toRawObject(bucket string) *raw.Object { + acl := toRawObjectACL(o.ACL) + return &raw.Object{ + Bucket: bucket, + Name: o.Name, + ContentType: o.ContentType, + ContentEncoding: o.ContentEncoding, + ContentLanguage: o.ContentLanguage, + CacheControl: o.CacheControl, + ContentDisposition: o.ContentDisposition, + Acl: acl, + Metadata: o.Metadata, + } +} + +// ObjectAttrs represents the metadata for a Google Cloud Storage (GCS) object. +type ObjectAttrs struct { + // Bucket is the name of the bucket containing this GCS object. + // This field is read-only. + Bucket string + + // Name is the name of the object within the bucket. + // This field is read-only. + Name string + + // ContentType is the MIME type of the object's content. + ContentType string + + // ContentLanguage is the content language of the object's content. + ContentLanguage string + + // CacheControl is the Cache-Control header to be sent in the response + // headers when serving the object data. + CacheControl string + + // ACL is the list of access control rules for the object. + ACL []ACLRule + + // Owner is the owner of the object. This field is read-only. + // + // If non-zero, it is in the form of "user-<userId>". + Owner string + + // Size is the length of the object's content. This field is read-only. + Size int64 + + // ContentEncoding is the encoding of the object's content. + ContentEncoding string + + // ContentDisposition is the optional Content-Disposition header of the object + // sent in the response headers. + ContentDisposition string + + // MD5 is the MD5 hash of the object's content. This field is read-only. + MD5 []byte + + // CRC32C is the CRC32 checksum of the object's content using + // the Castagnoli93 polynomial. This field is read-only. + CRC32C uint32 + + // MediaLink is an URL to the object's content. This field is read-only. + MediaLink string + + // Metadata represents user-provided metadata, in key/value pairs. + // It can be nil if no metadata is provided. + Metadata map[string]string + + // Generation is the generation number of the object's content. + // This field is read-only. + Generation int64 + + // MetaGeneration is the version of the metadata for this + // object at this generation. This field is used for preconditions + // and for detecting changes in metadata. A metageneration number + // is only meaningful in the context of a particular generation + // of a particular object. This field is read-only. + MetaGeneration int64 + + // StorageClass is the storage class of the bucket. + // This value defines how objects in the bucket are stored and + // determines the SLA and the cost of storage. Typical values are + // "STANDARD" and "DURABLE_REDUCED_AVAILABILITY". + // It defaults to "STANDARD". This field is read-only. + StorageClass string + + // Created is the time the object was created. This field is read-only. + Created time.Time + + // Deleted is the time the object was deleted. + // If not deleted, it is the zero value. This field is read-only. + Deleted time.Time + + // Updated is the creation or modification time of the object. + // For buckets with versioning enabled, changing an object's + // metadata does not change this property. This field is read-only. + Updated time.Time + + // Prefix is set only for ObjectAttrs which represent synthetic "directory + // entries" when iterating over buckets using Query.Delimiter. See + // ObjectIterator.Next. When set, no other fields in ObjectAttrs will be + // populated. + Prefix string +} + +// convertTime converts a time in RFC3339 format to time.Time. +// If any error occurs in parsing, the zero-value time.Time is silently returned. +func convertTime(t string) time.Time { + var r time.Time + if t != "" { + r, _ = time.Parse(time.RFC3339, t) + } + return r +} + +func newObject(o *raw.Object) *ObjectAttrs { + if o == nil { + return nil + } + acl := make([]ACLRule, len(o.Acl)) + for i, rule := range o.Acl { + acl[i] = ACLRule{ + Entity: ACLEntity(rule.Entity), + Role: ACLRole(rule.Role), + } + } + owner := "" + if o.Owner != nil { + owner = o.Owner.Entity + } + md5, _ := base64.StdEncoding.DecodeString(o.Md5Hash) + var crc32c uint32 + d, err := base64.StdEncoding.DecodeString(o.Crc32c) + if err == nil && len(d) == 4 { + crc32c = uint32(d[0])<<24 + uint32(d[1])<<16 + uint32(d[2])<<8 + uint32(d[3]) + } + return &ObjectAttrs{ + Bucket: o.Bucket, + Name: o.Name, + ContentType: o.ContentType, + ContentLanguage: o.ContentLanguage, + CacheControl: o.CacheControl, + ACL: acl, + Owner: owner, + ContentEncoding: o.ContentEncoding, + Size: int64(o.Size), + MD5: md5, + CRC32C: crc32c, + MediaLink: o.MediaLink, + Metadata: o.Metadata, + Generation: o.Generation, + MetaGeneration: o.Metageneration, + StorageClass: o.StorageClass, + Created: convertTime(o.TimeCreated), + Deleted: convertTime(o.TimeDeleted), + Updated: convertTime(o.Updated), + } +} + +// Query represents a query to filter objects from a bucket. +type Query struct { + // Delimiter returns results in a directory-like fashion. + // Results will contain only objects whose names, aside from the + // prefix, do not contain delimiter. Objects whose names, + // aside from the prefix, contain delimiter will have their name, + // truncated after the delimiter, returned in prefixes. + // Duplicate prefixes are omitted. + // Optional. + Delimiter string + + // Prefix is the prefix filter to query objects + // whose names begin with this prefix. + // Optional. + Prefix string + + // Versions indicates whether multiple versions of the same + // object will be included in the results. + Versions bool + + // Cursor is a previously-returned page token + // representing part of the larger set of results to view. + // Optional. + // + // Deprecated: Use ObjectIterator.PageInfo().Token instead. + Cursor string + + // MaxResults is the maximum number of items plus prefixes + // to return. As duplicate prefixes are omitted, + // fewer total results may be returned than requested. + // The default page limit is used if it is negative or zero. + // + // Deprecated: Use ObjectIterator.PageInfo().MaxSize instead. + MaxResults int +} + +// contentTyper implements ContentTyper to enable an +// io.ReadCloser to specify its MIME type. +type contentTyper struct { + io.Reader + t string +} + +func (c *contentTyper) ContentType() string { + return c.t +} + +// A Condition constrains methods to act on specific generations of +// resources. +// +// Not all conditions or combinations of conditions are applicable to +// all methods. +type Condition interface { + // method is the high-level ObjectHandle method name, for + // error messages. call is the call object to modify. + modifyCall(method string, call interface{}) error +} + +// applyConds modifies the provided call using the conditions in conds. +// call is something that quacks like a *raw.WhateverCall. +func applyConds(method string, conds []Condition, call interface{}) error { + for _, cond := range conds { + if err := cond.modifyCall(method, call); err != nil { + return err + } + } + return nil +} + +// toSourceConds returns a slice of Conditions derived from Conds that instead +// function on the equivalent Source methods of a call. +func toSourceConds(conds []Condition) []Condition { + out := make([]Condition, 0, len(conds)) + for _, c := range conds { + switch c := c.(type) { + case genCond: + var m string + if strings.HasPrefix(c.method, "If") { + m = "IfSource" + c.method[2:] + } else { + m = "Source" + c.method + } + out = append(out, genCond{method: m, val: c.val}) + default: + // NOTE(djd): If the message from unsupportedCond becomes + // confusing, we'll need to find a way for Conditions to + // identify themselves. + out = append(out, unsupportedCond{}) + } + } + return out +} + +func Generation(gen int64) Condition { return genCond{"Generation", gen} } +func IfGenerationMatch(gen int64) Condition { return genCond{"IfGenerationMatch", gen} } +func IfGenerationNotMatch(gen int64) Condition { return genCond{"IfGenerationNotMatch", gen} } +func IfMetaGenerationMatch(gen int64) Condition { return genCond{"IfMetagenerationMatch", gen} } +func IfMetaGenerationNotMatch(gen int64) Condition { return genCond{"IfMetagenerationNotMatch", gen} } + +type genCond struct { + method string + val int64 +} + +func (g genCond) modifyCall(srcMethod string, call interface{}) error { + rv := reflect.ValueOf(call) + meth := rv.MethodByName(g.method) + if !meth.IsValid() { + return fmt.Errorf("%s: condition %s not supported", srcMethod, g.method) + } + meth.Call([]reflect.Value{reflect.ValueOf(g.val)}) + return nil +} + +type unsupportedCond struct{} + +func (unsupportedCond) modifyCall(srcMethod string, call interface{}) error { + return fmt.Errorf("%s: condition not supported", srcMethod) +} + +func appendParam(req *http.Request, k, v string) { + sep := "" + if req.URL.RawQuery != "" { + sep = "&" + } + req.URL.RawQuery += sep + url.QueryEscape(k) + "=" + url.QueryEscape(v) +} + +// objectsGetCall wraps an *http.Request for an object fetch call, but adds the methods +// that modifyCall searches for by name. (the same names as the raw, auto-generated API) +type objectsGetCall struct{ req *http.Request } + +func (c objectsGetCall) Generation(gen int64) { + appendParam(c.req, "generation", fmt.Sprint(gen)) +} +func (c objectsGetCall) IfGenerationMatch(gen int64) { + appendParam(c.req, "ifGenerationMatch", fmt.Sprint(gen)) +} +func (c objectsGetCall) IfGenerationNotMatch(gen int64) { + appendParam(c.req, "ifGenerationNotMatch", fmt.Sprint(gen)) +} +func (c objectsGetCall) IfMetagenerationMatch(gen int64) { + appendParam(c.req, "ifMetagenerationMatch", fmt.Sprint(gen)) +} +func (c objectsGetCall) IfMetagenerationNotMatch(gen int64) { + appendParam(c.req, "ifMetagenerationNotMatch", fmt.Sprint(gen)) +} + +// composeSourceObj wraps a *raw.ComposeRequestSourceObjects, but adds the methods +// that modifyCall searches for by name. +type composeSourceObj struct { + src *raw.ComposeRequestSourceObjects +} + +func (c composeSourceObj) Generation(gen int64) { + c.src.Generation = gen +} + +func (c composeSourceObj) IfGenerationMatch(gen int64) { + // It's safe to overwrite ObjectPreconditions, since its only field is + // IfGenerationMatch. + c.src.ObjectPreconditions = &raw.ComposeRequestSourceObjectsObjectPreconditions{ + IfGenerationMatch: gen, + } +} + +// TODO(jbd): Add storage.objects.watch. |