Add mimetype mapping settings (#15133)

* Fix APK's Content-Type header

* Fix case sensitive comparison

* Add custom mime type mapping for downloadable files

* Add documentation for MIME type mapping

* Rename download.mimetype.mapping configuration to repository.mimetype_mapping

Co-authored-by: zeripath <art27@cantab.net>

modules/setting/mime_type_map.go

@@ -0,0 +1,31 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package setting
+
+import "strings"
+
+var (
+	// MimeTypeMap defines custom mime type mapping settings
+	MimeTypeMap = struct {
+		Enabled bool
+		Map     map[string]string
+	}{
+		Enabled: false,
+		Map:     map[string]string{},
+	}
+)
+
+func newMimeTypeMap() {
+	sec := Cfg.Section("repository.mimetype_mapping")
+	keys := sec.Keys()
+	m := make(map[string]string, len(keys))
+	for _, key := range keys {
+		m[strings.ToLower(key.Name())] = key.Value()
+	}
+	MimeTypeMap.Map = m
+	if len(keys) > 0 {
+		MimeTypeMap.Enabled = true
+	}
+}

modules/setting/setting.go

@@ -1177,4 +1177,5 @@ func NewServices() {
 	newTaskService()
 	NewQueueService()
 	newProject()
+	newMimeTypeMap()
 }