micro/util/structfs/structfs.go

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package structfs
import (
"fmt"
"io"
"net/http"
"os"
"reflect"
"strings"
"time"
)
// FileServer creates new file server from the struct iface with specific tag and specific modtime
func FileServer(iface interface{}, tag string, modtime time.Time) http.Handler {
if modtime.IsZero() {
modtime = time.Now()
}
return &fs{iface: iface, tag: tag, modtime: modtime}
}
func (fs *fs) ServeHTTP(w http.ResponseWriter, r *http.Request) {
upath := r.URL.Path
if !strings.HasPrefix(upath, "/") {
upath = "/" + upath
r.URL.Path = upath
}
f, err := fs.Open(r.URL.Path)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
w.Write([]byte(err.Error()))
return
}
w.Header().Set("Content-Type", "application/octet-stream")
http.ServeContent(w, r, r.URL.Path, fs.modtime, f)
}
type fs struct {
iface interface{}
tag string
modtime time.Time
}
type file struct {
name string
offset int64
data []byte
modtime time.Time
}
type fileInfo struct {
name string
size int64
modtime time.Time
}
func (fi *fileInfo) Sys() interface{} {
return nil
}
func (fi *fileInfo) Size() int64 {
return fi.size
}
func (fi *fileInfo) Name() string {
return fi.name
}
func (fi *fileInfo) Mode() os.FileMode {
if strings.HasSuffix(fi.name, "/") {
return os.FileMode(0755) | os.ModeDir
}
return os.FileMode(0644)
}
func (fi *fileInfo) IsDir() bool {
// disables additional open /index.html
return false
}
func (fi *fileInfo) ModTime() time.Time {
return fi.modtime
}
func (f *file) Close() error {
return nil
}
func (f *file) Read(b []byte) (int, error) {
var err error
var n int
if f.offset >= int64(len(f.data)) {
return 0, io.EOF
}
if len(f.data) > 0 {
n = copy(b, f.data[f.offset:])
}
if n < len(b) {
err = io.EOF
}
f.offset += int64(n)
return n, err
}
func (f *file) Readdir(count int) ([]os.FileInfo, error) {
return nil, nil
}
func (f *file) Seek(offset int64, whence int) (int64, error) {
// log.Printf("seek %d %d %s\n", offset, whence, f.name)
switch whence {
case os.SEEK_SET:
f.offset = offset
case os.SEEK_CUR:
f.offset += offset
case os.SEEK_END:
f.offset = int64(len(f.data)) + offset
}
return f.offset, nil
}
func (f *file) Stat() (os.FileInfo, error) {
return &fileInfo{name: f.name, size: int64(len(f.data)), modtime: f.modtime}, nil
}
func (fs *fs) Open(path string) (http.File, error) {
return newFile(path, fs.iface, fs.tag, fs.modtime)
}
func newFile(name string, iface interface{}, tag string, modtime time.Time) (*file, error) {
var err error
f := &file{name: name, modtime: modtime}
f.data, err = structItem(name, iface, tag)
if err != nil {
return nil, err
}
return f, nil
}
func structItem(path string, iface interface{}, tag string) ([]byte, error) {
var buf []byte
var err error
var curiface interface{}
if path == "/" {
return getNames(iface, tag)
}
idx := strings.Index(path[1:], "/")
switch {
case idx > 0:
curiface, err = getStruct(path[1:idx+1], iface, tag)
if err != nil {
return nil, err
}
buf, err = structItem(path[idx+1:], curiface, tag)
case idx == 0:
return getNames(iface, tag)
case idx < 0:
return getValue(path[1:], iface, tag)
}
return buf, err
}
func getNames(iface interface{}, tag string) ([]byte, error) {
var lines []string
s := reflectValue(iface)
typeOf := s.Type()
for i := 0; i < s.NumField(); i++ {
value := typeOf.Field(i).Tag.Get(tag)
if value != "" {
lines = append(lines, value)
}
}
if len(lines) > 0 {
return []byte(strings.Join(lines, "\n")), nil
}
return nil, fmt.Errorf("failed to find names")
}
func getStruct(name string, iface interface{}, tag string) (interface{}, error) {
s := reflectValue(iface)
typeOf := s.Type()
for i := 0; i < s.NumField(); i++ {
if typeOf.Field(i).Tag.Get(tag) == name {
return s.Field(i).Interface(), nil
}
}
return nil, fmt.Errorf("failed to find iface %T with name %s", iface, name)
}
func getValue(name string, iface interface{}, tag string) ([]byte, error) {
s := reflectValue(iface)
typeOf := s.Type()
switch typeOf.Kind() {
case reflect.Map:
return []byte(fmt.Sprintf("%v", s.MapIndex(reflect.ValueOf(name)).Interface())), nil
default:
for i := 0; i < s.NumField(); i++ {
if typeOf.Field(i).Tag.Get(tag) != name {
continue
}
ifs := s.Field(i).Interface()
switch s.Field(i).Kind() {
case reflect.Slice:
var lines []string
for k := 0; k < s.Field(i).Len(); k++ {
lines = append(lines, fmt.Sprintf("%v", s.Field(i).Index(k)))
}
return []byte(strings.Join(lines, "\n")), nil
default:
return []byte(fmt.Sprintf("%v", ifs)), nil
}
}
}
return nil, fmt.Errorf("failed to find %s in interface %T", name, iface)
}
func hasValidType(obj interface{}, types []reflect.Kind) bool {
for _, t := range types {
if reflect.TypeOf(obj).Kind() == t {
return true
}
}
return false
}
func reflectValue(obj interface{}) reflect.Value {
var val reflect.Value
if reflect.TypeOf(obj).Kind() == reflect.Ptr {
val = reflect.ValueOf(obj).Elem()
} else {
val = reflect.ValueOf(obj)
}
return val
}