cmd/swarm: fix error handling in 'swarm up' (#14557)

The error returned by client.Upload was previously being ignored due to becoming
out of scope outside the if statement. This has been fixed by instead defining a
function which returns the hash and error (rather than trying to set the hash in
each branch of the if statement).

cmd/swarm/upload.go

@@ -18,6 +18,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -87,24 +88,32 @@ func upload(ctx *cli.Context) {
 	if err != nil {
 		utils.Fatalf("Error opening file: %s", err)
 	}
-	var hash string
+
+	// define a function which either uploads a directory or single file
+	// based on the type of the file being uploaded
+	var doUpload func() (hash string, err error)
 	if stat.IsDir() {
+		doUpload = func() (string, error) {
 			if !recursive {
-			utils.Fatalf("Argument is a directory and recursive upload is disabled")
+				return "", errors.New("Argument is a directory and recursive upload is disabled")
 			}
-		hash, err = client.UploadDirectory(file, defaultPath, "")
-	} else {
-		if mimeType == "" {
-			mimeType = detectMimeType(file)
+			return client.UploadDirectory(file, defaultPath, "")
 		}
+	} else {
+		doUpload = func() (string, error) {
 			f, err := swarm.Open(file)
 			if err != nil {
-			utils.Fatalf("Error opening file: %s", err)
+				return "", fmt.Errorf("error opening file: %s", err)
 			}
 			defer f.Close()
+			if mimeType == "" {
+				mimeType = detectMimeType(file)
+			}
 			f.ContentType = mimeType
-		hash, err = client.Upload(f, "")
+			return client.Upload(f, "")
+		}
 	}
+	hash, err := doUpload()
 	if err != nil {
 		utils.Fatalf("Upload failed: %s", err)
 	}