Migrate Sirupsen to sirupsen.

vendor/github.com/docker/distribution/registry/storage/io.go

@@ -0,0 +1,71 @@
+package storage
+
+import (
+	"errors"
+	"io"
+	"io/ioutil"
+
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/registry/storage/driver"
+)
+
+const (
+	maxBlobGetSize = 4 << 20
+)
+
+func getContent(ctx context.Context, driver driver.StorageDriver, p string) ([]byte, error) {
+	r, err := driver.Reader(ctx, p, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	return readAllLimited(r, maxBlobGetSize)
+}
+
+func readAllLimited(r io.Reader, limit int64) ([]byte, error) {
+	r = limitReader(r, limit)
+	return ioutil.ReadAll(r)
+}
+
+// limitReader returns a new reader limited to n bytes. Unlike io.LimitReader,
+// this returns an error when the limit reached.
+func limitReader(r io.Reader, n int64) io.Reader {
+	return &limitedReader{r: r, n: n}
+}
+
+// limitedReader implements a reader that errors when the limit is reached.
+//
+// Partially cribbed from net/http.MaxBytesReader.
+type limitedReader struct {
+	r   io.Reader // underlying reader
+	n   int64     // max bytes remaining
+	err error     // sticky error
+}
+
+func (l *limitedReader) Read(p []byte) (n int, err error) {
+	if l.err != nil {
+		return 0, l.err
+	}
+	if len(p) == 0 {
+		return 0, nil
+	}
+	// If they asked for a 32KB byte read but only 5 bytes are
+	// remaining, no need to read 32KB. 6 bytes will answer the
+	// question of the whether we hit the limit or go past it.
+	if int64(len(p)) > l.n+1 {
+		p = p[:l.n+1]
+	}
+	n, err = l.r.Read(p)
+
+	if int64(n) <= l.n {
+		l.n -= int64(n)
+		l.err = err
+		return n, err
+	}
+
+	n = int(l.n)
+	l.n = 0
+
+	l.err = errors.New("storage: read exceeds limit")
+	return n, l.err
+}