mirror of
https://github.com/zeromicro/go-zero.git
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93 lines
2.2 KiB
Go
93 lines
2.2 KiB
Go
package fileserver
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import (
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"net/http"
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pathpkg "path"
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"strings"
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"sync"
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)
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// Middleware returns a middleware that serves files from the given file system.
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func Middleware(path string, fs http.FileSystem) func(http.HandlerFunc) http.HandlerFunc {
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fileServer := http.FileServer(fs)
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pathWithoutTrailSlash := ensureNoTrailingSlash(path)
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canServe := createServeChecker(path, fs)
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return func(next http.HandlerFunc) http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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if canServe(r) {
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r.URL.Path = r.URL.Path[len(pathWithoutTrailSlash):]
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fileServer.ServeHTTP(w, r)
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} else {
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next(w, r)
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}
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}
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}
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}
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func createFileChecker(fs http.FileSystem) func(string) bool {
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var lock sync.RWMutex
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fileChecker := make(map[string]bool)
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return func(path string) bool {
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// Emulate http.Dir.Open’s path normalization for embed.FS.Open.
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// http.FileServer redirects any request ending in "/index.html"
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// to the same path without the final "index.html".
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// So the path here may be empty or end with a "/".
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// http.Dir.Open uses this logic to clean the path,
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// correctly handling those two cases.
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// embed.FS doesn’t perform this normalization, so we apply the same logic here.
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path = pathpkg.Clean("/" + path)[1:]
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if path == "" {
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path = "."
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}
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lock.RLock()
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exist, ok := fileChecker[path]
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lock.RUnlock()
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if ok {
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return exist
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}
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lock.Lock()
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defer lock.Unlock()
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file, err := fs.Open(path)
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exist = err == nil
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fileChecker[path] = exist
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if err != nil {
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return false
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}
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_ = file.Close()
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return true
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}
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}
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func createServeChecker(path string, fs http.FileSystem) func(r *http.Request) bool {
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pathWithTrailSlash := ensureTrailingSlash(path)
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fileChecker := createFileChecker(fs)
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return func(r *http.Request) bool {
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return r.Method == http.MethodGet &&
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strings.HasPrefix(r.URL.Path, pathWithTrailSlash) &&
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fileChecker(r.URL.Path[len(pathWithTrailSlash):])
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}
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}
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func ensureTrailingSlash(path string) string {
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if strings.HasSuffix(path, "/") {
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return path
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}
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return path + "/"
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}
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func ensureNoTrailingSlash(path string) string {
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if strings.HasSuffix(path, "/") {
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return path[:len(path)-1]
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}
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return path
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}
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