Merge pull request #11 from drone-plugins/checksum-fix

Copy the target file first and fix checksum checks

plugin.go

@@ -107,39 +107,45 @@ func (p Plugin) Exec() error {
 
 	defer target.Close()
 
-	if p.Config.MD5 != "" {
-		h := md5.New()
-
-		if _, err := io.Copy(h, resp.Body); err != nil {
-			return errors.Wrap(err, "failed to compare checksum")
-		}
-
-		check := fmt.Sprintf("%x", h.Sum(nil))
-
-		if p.Config.MD5 != check {
-			return fmt.Errorf("checksum doesn't match, got %s and expected %s", check, p.Config.MD5)
-		}
-	}
-
-	if p.Config.SHA256 != "" {
-		h := sha256.New()
-
-		if _, err := io.Copy(h, resp.Body); err != nil {
-			return errors.Wrap(err, "failed to compare checksum")
-		}
-
-		check := fmt.Sprintf("%x", h.Sum(nil))
-
-		if p.Config.SHA256 != check {
-			return fmt.Errorf("checksum doesn't match, got %s and expected %s", check, p.Config.SHA256)
-		}
-	}
-
 	_, err = io.Copy(target, resp.Body)
 
 	if err != nil {
 		return errors.Wrap(err, "copying destination failed")
 	}
 
+	if p.Config.MD5 != "" {
+		h := md5.New()
+		target.Seek(0, 0)
+
+		if _, err := io.Copy(h, target); err != nil {
+			defer os.Remove(target.Name())
+			return errors.Wrap(err, "failed to compare checksum")
+		}
+
+		check := fmt.Sprintf("%x", h.Sum(nil))
+
+		if p.Config.MD5 != check {
+			defer os.Remove(target.Name())
+			return fmt.Errorf("checksum doesn't match, got %s and expected %s", check, p.Config.MD5)
+		}
+	}
+
+	if p.Config.SHA256 != "" {
+		h := sha256.New()
+		target.Seek(0, 0)
+
+		if _, err := io.Copy(h, target); err != nil {
+			defer os.Remove(target.Name())
+			return errors.Wrap(err, "failed to compare checksum")
+		}
+
+		check := fmt.Sprintf("%x", h.Sum(nil))
+
+		if p.Config.SHA256 != check {
+			defer os.Remove(target.Name())
+			return fmt.Errorf("checksum doesn't match, got %s and expected %s", check, p.Config.SHA256)
+		}
+	}
+
 	return nil
 }