s3 cache client-side support

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

vendor/github.com/aws/smithy-go/transport/http/request.go

@@ -0,0 +1,180 @@
+package http
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+
+	iointernal "github.com/aws/smithy-go/transport/http/internal/io"
+)
+
+// Request provides the HTTP specific request structure for HTTP specific
+// middleware steps to use to serialize input, and send an operation's request.
+type Request struct {
+	*http.Request
+	stream           io.Reader
+	isStreamSeekable bool
+	streamStartPos   int64
+}
+
+// NewStackRequest returns an initialized request ready to be populated with the
+// HTTP request details. Returns empty interface so the function can be used as
+// a parameter to the Smithy middleware Stack constructor.
+func NewStackRequest() interface{} {
+	return &Request{
+		Request: &http.Request{
+			URL:           &url.URL{},
+			Header:        http.Header{},
+			ContentLength: -1, // default to unknown length
+		},
+	}
+}
+
+// Clone returns a deep copy of the Request for the new context. A reference to
+// the Stream is copied, but the underlying stream is not copied.
+func (r *Request) Clone() *Request {
+	rc := *r
+	rc.Request = rc.Request.Clone(context.TODO())
+	return &rc
+}
+
+// StreamLength returns the number of bytes of the serialized stream attached
+// to the request and ok set. If the length cannot be determined, an error will
+// be returned.
+func (r *Request) StreamLength() (size int64, ok bool, err error) {
+	return streamLength(r.stream, r.isStreamSeekable, r.streamStartPos)
+}
+
+func streamLength(stream io.Reader, seekable bool, startPos int64) (size int64, ok bool, err error) {
+	if stream == nil {
+		return 0, true, nil
+	}
+
+	if l, ok := stream.(interface{ Len() int }); ok {
+		return int64(l.Len()), true, nil
+	}
+
+	if !seekable {
+		return 0, false, nil
+	}
+
+	s := stream.(io.Seeker)
+	endOffset, err := s.Seek(0, io.SeekEnd)
+	if err != nil {
+		return 0, false, err
+	}
+
+	// The reason to seek to streamStartPos instead of 0 is to ensure that the
+	// SDK only sends the stream from the starting position the user's
+	// application provided it to the SDK at. For example application opens a
+	// file, and wants to skip the first N bytes uploading the rest. The
+	// application would move the file's offset N bytes, then hand it off to
+	// the SDK to send the remaining. The SDK should respect that initial offset.
+	_, err = s.Seek(startPos, io.SeekStart)
+	if err != nil {
+		return 0, false, err
+	}
+
+	return endOffset - startPos, true, nil
+}
+
+// RewindStream will rewind the io.Reader to the relative start position if it
+// is an io.Seeker.
+func (r *Request) RewindStream() error {
+	// If there is no stream there is nothing to rewind.
+	if r.stream == nil {
+		return nil
+	}
+
+	if !r.isStreamSeekable {
+		return fmt.Errorf("request stream is not seekable")
+	}
+	_, err := r.stream.(io.Seeker).Seek(r.streamStartPos, io.SeekStart)
+	return err
+}
+
+// GetStream returns the request stream io.Reader if a stream is set. If no
+// stream is present nil will be returned.
+func (r *Request) GetStream() io.Reader {
+	return r.stream
+}
+
+// IsStreamSeekable returns whether the stream is seekable.
+func (r *Request) IsStreamSeekable() bool {
+	return r.isStreamSeekable
+}
+
+// SetStream returns a clone of the request with the stream set to the provided
+// reader. May return an error if the provided reader is seekable but returns
+// an error.
+func (r *Request) SetStream(reader io.Reader) (rc *Request, err error) {
+	rc = r.Clone()
+
+	if reader == http.NoBody {
+		reader = nil
+	}
+
+	var isStreamSeekable bool
+	var streamStartPos int64
+	switch v := reader.(type) {
+	case io.Seeker:
+		n, err := v.Seek(0, io.SeekCurrent)
+		if err != nil {
+			return r, err
+		}
+		isStreamSeekable = true
+		streamStartPos = n
+	default:
+		// If the stream length can be determined, and is determined to be empty,
+		// use a nil stream to prevent confusion between empty vs not-empty
+		// streams.
+		length, ok, err := streamLength(reader, false, 0)
+		if err != nil {
+			return nil, err
+		} else if ok && length == 0 {
+			reader = nil
+		}
+	}
+
+	rc.stream = reader
+	rc.isStreamSeekable = isStreamSeekable
+	rc.streamStartPos = streamStartPos
+
+	return rc, err
+}
+
+// Build returns a build standard HTTP request value from the Smithy request.
+// The request's stream is wrapped in a safe container that allows it to be
+// reused for subsequent attempts.
+func (r *Request) Build(ctx context.Context) *http.Request {
+	req := r.Request.Clone(ctx)
+
+	if r.stream == nil && req.ContentLength == -1 {
+		req.ContentLength = 0
+	}
+
+	switch stream := r.stream.(type) {
+	case *io.PipeReader:
+		req.Body = ioutil.NopCloser(stream)
+		req.ContentLength = -1
+	default:
+		// HTTP Client Request must only have a non-nil body if the
+		// ContentLength is explicitly unknown (-1) or non-zero. The HTTP
+		// Client will interpret a non-nil body and ContentLength 0 as
+		// "unknown". This is unwanted behavior.
+		if req.ContentLength != 0 && r.stream != nil {
+			req.Body = iointernal.NewSafeReadCloser(ioutil.NopCloser(stream))
+		}
+	}
+
+	return req
+}
+
+// RequestCloner is a function that can take an input request type and clone the request
+// for use in a subsequent retry attempt.
+func RequestCloner(v interface{}) interface{} {
+	return v.(*Request).Clone()
+}