make spartan.Client.RoundTrip match the API of other clients.

- Request.Meta is already used as an *io.LimitedReader in spartan
  servers, so by following this convention the RoundTrip method doesn't
  need anything more than the *Request.
- Make a new public method for setting the body on a spartan request.

1 files changed, 21 insertions, 0 deletions

diff --git a/spartan/request.go b/spartan/request.go
index a9b2815..c056af0 100644
--- a/spartan/request.go
+++ b/spartan/request.go
@@ -2,6 +2,7 @@ package spartan
 
 import (
 	"bufio"
+	"bytes"
 	"errors"
 	"io"
 	"net/url"
@@ -80,3 +81,23 @@ func GetRequestBody(request *sr.Request) io.Reader {
 	}
 	return nil
 }
+
+// SetRequestBody adds an io.Reader as a request body.
+//
+// It is for use in clients, preparing the request to be sent.
+//
+// This function will read the entire contents into memory unless
+// the reader is already an *io.LimitedReader.
+func SetRequestBody(request *sr.Request, body io.Reader) error {
+	if rdr, ok := body.(*io.LimitedReader); ok {
+		request.Meta = rdr
+		return nil
+	}
+
+	buf, err := io.ReadAll(body)
+	if err != nil {
+		return err
+	}
+	request.Meta = io.LimitReader(bytes.NewBuffer(buf), int64(len(buf)))
+	return nil
+}