Add documentation for MIME type mapping

Author: szatyinadam

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -966,6 +966,15 @@ MINIO_USE_SSL = false
 
 And used by `[attachment]`, `[lfs]` and etc. as `STORAGE_TYPE`.
 
+## MIME type mapping (`download.mimetype.mapping`)
+
+Configuration for set the expected MIME type based on file extensions of downloadable files. Configuration presents in key-value pairs and file extensions starts with leading `.`.
+
+The following configuration set `Content-Type: application/javascript` header when downloading files with `.js` file extension.
+```ini
+.js=application/javascript
+```
+
 ## Other (`other`)
 
 - `SHOW_FOOTER_BRANDING`: **false**: Show Gitea branding in the footer.

modules/base/tool.go

@@ -332,11 +332,6 @@ func IsAudioFile(data []byte) bool {
 	return strings.Contains(DetectContentType(data), "audio/")
 }
 
-// IsZipFile detects if data is a zip format
-func IsZipFile(data []byte) bool {
-	return strings.Contains(DetectContentType(data), "application/zip")
-}
-
 // EntryIcon returns the octicon class for displaying files/directories
 func EntryIcon(entry *git.TreeEntry) string {
 	switch {

modules/base/tool_test.go

@@ -329,12 +329,6 @@ func TestIsAudioFile(t *testing.T) {
 	assert.False(t, IsAudioFile([]byte("plain text")))
 }
 
-func TestIsZipFile(t *testing.T) {
-	zip, _ := base64.StdEncoding.DecodeString("UEsDBAoAAAAAANG0d1IAAAAAAAAAAAAAAAAIABwAdGV4dC50eHRVVAkAA9pfWmDaX1pgdXgLAAEE9QEAAAQUAAAAUEsBAh4DCgAAAAAA0bR3UgAAAAAAAAAAAAAAAAgAGAAAAAAAAAAAAKSBAAAAAHRleHQudHh0VVQFAAPaX1pgdXgLAAEE9QEAAAQUAAAAUEsFBgAAAAABAAEATgAAAEIAAAAAAA==")
-	assert.True(t, IsZipFile(zip))
-	assert.False(t, IsZipFile([]byte("plain text")))
-}
-
 // TODO: Test EntryIcon
 
 func TestSetupGiteaRoot(t *testing.T) {

modules/setting/mime_type_map.go

@@ -4,6 +4,8 @@
 
 package setting
 
+import "strings"
+
 var (
 	// MimeTypeMap defines custom mime type mapping settings
 	MimeTypeMap = struct {
@@ -20,7 +22,7 @@ func newMimeTypeMap() {
 	keys := sec.Keys()
 	m := make(map[string]string, len(keys))
 	for _, key := range keys {
-		m[key.Name()] = key.Value()
+		m[strings.ToLower(key.Name())] = key.Value()
 	}
 	MimeTypeMap.Map = m
 	if len(keys) > 0 {

routers/repo/download.go

@@ -64,7 +64,8 @@ func ServeData(ctx *context.Context, name string, size int64, reader io.Reader)
 		ctx.Resp.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="%s"`, name))
 		ctx.Resp.Header().Set("Access-Control-Expose-Headers", "Content-Disposition")
 		if setting.MimeTypeMap.Enabled {
-			if mimetype, ok := setting.MimeTypeMap.Map[filepath.Ext(name)]; ok {
+			fileExtension := strings.ToLower(filepath.Ext(name))
+			if mimetype, ok := setting.MimeTypeMap.Map[fileExtension]; ok {
 				ctx.Resp.Header().Set("Content-Type", mimetype)
 			}
 		}