(fea) CurlFS as an abstraction for pre-signed URLs

file.go

@@ -137,7 +137,7 @@ func (fd *reader[T]) lazyOpen() error {
 
 	fd.fs.codec.DecodeGetOutput(val, fd.info.attr)
 	if fd.fs.signer != nil && fd.fs.codec.s != nil {
-		if url, err := fd.fs.preSignGetUrl(fd.s3Key(fd.fs.root)); err == nil {
+		if url, err := fd.fs.preSignGetUrl(fd.s3Key(fd.fs.root), fd.fs.ttlSignedUrl); err == nil {
 			fd.fs.codec.s.Put(fd.info.attr, url)
 		}
 	}
@@ -234,29 +234,6 @@ func (fd *writer[T]) lazyOpen() {
 	}()
 }
 
-func (fd *writer[T]) preSignPutUrl() (string, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), fd.fs.timeout)
-	defer cancel()
-
-	req := &s3.PutObjectInput{
-		Bucket:   aws.String(fd.fs.bucket),
-		Key:      fd.s3Key(fd.fs.root),
-		Metadata: make(map[string]string),
-	}
-	fd.fs.codec.EncodePutInput(fd.attr, req)
-
-	val, err := fd.fs.signer.PresignPutObject(ctx, req, s3.WithPresignExpires(fd.fs.ttlSignedUrl))
-	if err != nil {
-		return "", &fs.PathError{
-			Op:   "presign",
-			Path: fd.path,
-			Err:  err,
-		}
-	}
-
-	return val.URL, nil
-}
-
 func (fd *writer[T]) Write(p []byte) (int, error) {
 	if fd.r == nil && fd.w == nil {
 		fd.lazyOpen()
@@ -300,7 +277,7 @@ func (fd *writer[T]) Stat() (fs.FileInfo, error) {
 			fd.info.attr = new(T)
 		}
 
-		if url, err := fd.preSignPutUrl(); err == nil {
+		if url, err := fd.fs.preSignPutUrl(fd.s3Key(fd.fs.root), fd.info.attr, fd.fs.ttlSignedUrl); err == nil {
 			fd.fs.codec.s.Put(fd.info.attr, url)
 		}
 	}

filesystem.go

@@ -44,6 +44,7 @@ var (
 	_ CreateFS[struct{}] = (*FileSystem[struct{}])(nil)
 	_ RemoveFS           = (*FileSystem[struct{}])(nil)
 	_ CopyFS             = (*FileSystem[struct{}])(nil)
+	_ CurlFS[struct{}]   = (*FileSystem[struct{}])(nil)
 )
 
 // Create a file system instance, mounting S3 Bucket. Use Option type to
@@ -156,7 +157,7 @@ func (fsys *FileSystem[T]) Stat(path string) (fs.FileInfo, error) {
 	fsys.codec.DecodeHeadOutput(val, info.attr)
 
 	if fsys.signer != nil && fsys.codec.s != nil {
-		if url, err := fsys.preSignGetUrl(info.s3Key(fsys.root)); err == nil {
+		if url, err := fsys.preSignGetUrl(info.s3Key(fsys.root), fsys.ttlSignedUrl); err == nil {
 			fsys.codec.s.Put(info.attr, url)
 		}
 	}
@@ -174,7 +175,30 @@ func (fsys *FileSystem[T]) StatSys(stat fs.FileInfo) *T {
 	return info.attr
 }
 
-func (fsys *FileSystem[T]) preSignGetUrl(s3key *string) (string, error) {
+func (fsys *FileSystem[T]) preSignPutUrl(s3key *string, attr *T, ttl time.Duration) (string, error) {
+	req := &s3.PutObjectInput{
+		Bucket:   aws.String(fsys.bucket),
+		Key:      s3key,
+		Metadata: make(map[string]string),
+	}
+	fsys.codec.EncodePutInput(attr, req)
+
+	ctx, cancel := context.WithTimeout(context.Background(), fsys.timeout)
+	defer cancel()
+
+	val, err := fsys.signer.PresignPutObject(ctx, req, s3.WithPresignExpires(ttl))
+	if err != nil {
+		return "", &fs.PathError{
+			Op:   "presign",
+			Path: "/" + aws.ToString(s3key),
+			Err:  err,
+		}
+	}
+
+	return val.URL, nil
+}
+
+func (fsys *FileSystem[T]) preSignGetUrl(s3key *string, ttl time.Duration) (string, error) {
 	req := &s3.GetObjectInput{
 		Bucket: aws.String(fsys.bucket),
 		Key:    s3key,
@@ -183,7 +207,7 @@ func (fsys *FileSystem[T]) preSignGetUrl(s3key *string) (string, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), fsys.timeout)
 	defer cancel()
 
-	val, err := fsys.signer.PresignGetObject(ctx, req, s3.WithPresignExpires(fsys.ttlSignedUrl))
+	val, err := fsys.signer.PresignGetObject(ctx, req, s3.WithPresignExpires(ttl))
 	if err != nil {
 		return "", &fs.PathError{
 			Op:   "presign",
@@ -338,6 +362,38 @@ func (fsys *FileSystem[T]) Wait(path string, timeout time.Duration) error {
 	return nil
 }
 
+func (fsys *FileSystem[T]) PutFileUrl(path string, attr *T, ttl time.Duration) (string, error) {
+	if fsys.signer == nil {
+		return "", &fs.PathError{
+			Op:   "putfileurl",
+			Path: path,
+			Err:  errors.New("signer is not configured"),
+		}
+	}
+
+	if err := RequireValidPath("putfileurl", path); err != nil {
+		return "", err
+	}
+
+	return fsys.preSignPutUrl(s3Key(fsys.root, path), attr, ttl)
+}
+
+func (fsys *FileSystem[T]) GetFileUrl(path string, ttl time.Duration) (string, error) {
+	if fsys.signer == nil {
+		return "", &fs.PathError{
+			Op:   "getfileurl",
+			Path: path,
+			Err:  errors.New("signer is not configured"),
+		}
+	}
+
+	if err := RequireValidPath("getfileurl", path); err != nil {
+		return "", err
+	}
+
+	return fsys.preSignGetUrl(s3Key(fsys.root, path), ttl)
+}
+
 //------------------------------------------------------------------------------
 
 func recoverNoSuchKey(err error) bool {

types.go

@@ -56,6 +56,13 @@ type CopyFS interface {
 	Wait(path string, timeout time.Duration) error
 }
 
+// File System extension supporting I/O operations via urls
+type CurlFS[T any] interface {
+	fs.FS
+	PutFileUrl(path string, attr *T, ttl time.Duration) (string, error)
+	GetFileUrl(path string, ttl time.Duration) (string, error)
+}
+
 // well-known attributes controlled by S3 system
 type SystemMetadata struct {
 	CacheControl    string