add support for embedding templates and other static resources

This feature is disabled by default and can be enabled using the
"bundle" build tag

Fixes #823

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

internal/util/resources_embedded.go

@@ -0,0 +1,57 @@
+// Copyright (C) 2019-2022  Nicola Murino
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, version 3.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+//go:build bundle
+// +build bundle
+
+package util
+
+import (
+	"html/template"
+
+	"github.com/drakkan/sftpgo/v2/internal/bundle"
+	"github.com/drakkan/sftpgo/v2/internal/logger"
+)
+
+// FindSharedDataPath searches for the specified directory name in searchDir
+// and in system-wide shared data directories.
+// If name is an absolute path it is returned unmodified.
+func FindSharedDataPath(name, _ string) string {
+	return name
+}
+
+// LoadTemplate parses the given template paths.
+// It behaves like template.Must but it writes a log before exiting.
+// You can optionally provide a base template (e.g. to define some custom functions)
+func LoadTemplate(base *template.Template, paths ...string) *template.Template {
+	var t *template.Template
+	var err error
+
+	templateFs := bundle.GetTemplatesFs()
+	if base != nil {
+		base, err = base.Clone()
+		if err == nil {
+			t, err = base.ParseFS(templateFs, paths...)
+		}
+	} else {
+		t, err = template.ParseFS(templateFs, paths...)
+	}
+
+	if err != nil {
+		logger.ErrorToConsole("error loading required template: %v", err)
+		logger.Error(logSender, "", "error loading required template: %v", err)
+		panic(err)
+	}
+	return t
+}