[feature] Stream files via reader (#404)

* serve files via reader rather than byte slice

* close readcloser when we're done with it

* cast reader to readcloser

internal/api/client/fileserver/servefile.go

@@ -19,7 +19,7 @@
 package fileserver
 
 import (
-	"bytes"
+	"io"
 	"net/http"
 
 	"github.com/gin-gonic/gin"
@@ -91,6 +91,15 @@ func (m *FileServer) ServeFile(c *gin.Context) {
 		return
 	}
 
+	defer func() {
+		// if the content is a ReadCloser, close it when we're done
+		if closer, ok := content.Content.(io.ReadCloser); ok {
+			if err := closer.Close(); err != nil {
+				l.Errorf("error closing readcloser: %s", err)
+			}
+		}
+	}()
+
 	// TODO: if the requester only accepts text/html we should try to serve them *something*.
 	// This is mostly needed because when sharing a link to a gts-hosted file on something like mastodon, the masto servers will
 	// attempt to look up the content to provide a preview of the link, and they ask for text/html.
@@ -100,5 +109,5 @@ func (m *FileServer) ServeFile(c *gin.Context) {
 		return
 	}
 
-	c.DataFromReader(http.StatusOK, content.ContentLength, format, bytes.NewReader(content.Content), nil)
+	c.DataFromReader(http.StatusOK, content.ContentLength, format, content.Content, nil)
 }

internal/api/model/content.go

@@ -18,14 +18,16 @@
 
 package model
 
+import "io"
+
 // Content wraps everything needed to serve a blob of content (some kind of media) through the API.
 type Content struct {
 	// MIME content type
 	ContentType string
 	// ContentLength in bytes
 	ContentLength int64
-	// Actual content blob
-	Content []byte
+	// Actual content
+	Content io.Reader
 }
 
 // GetContentRequestForm describes a piece of content desired by the caller of the fileserver API.