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-rw-r--r--src/net/http/fs.go970
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diff --git a/src/net/http/fs.go b/src/net/http/fs.go
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+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// HTTP file system request handler
+
+package http
+
+import (
+ "errors"
+ "fmt"
+ "io"
+ "io/fs"
+ "mime"
+ "mime/multipart"
+ "net/textproto"
+ "net/url"
+ "os"
+ "path"
+ "path/filepath"
+ "sort"
+ "strconv"
+ "strings"
+ "time"
+)
+
+// A Dir implements FileSystem using the native file system restricted to a
+// specific directory tree.
+//
+// While the FileSystem.Open method takes '/'-separated paths, a Dir's string
+// value is a filename on the native file system, not a URL, so it is separated
+// by filepath.Separator, which isn't necessarily '/'.
+//
+// Note that Dir could expose sensitive files and directories. Dir will follow
+// symlinks pointing out of the directory tree, which can be especially dangerous
+// if serving from a directory in which users are able to create arbitrary symlinks.
+// Dir will also allow access to files and directories starting with a period,
+// which could expose sensitive directories like .git or sensitive files like
+// .htpasswd. To exclude files with a leading period, remove the files/directories
+// from the server or create a custom FileSystem implementation.
+//
+// An empty Dir is treated as ".".
+type Dir string
+
+// mapDirOpenError maps the provided non-nil error from opening name
+// to a possibly better non-nil error. In particular, it turns OS-specific errors
+// about opening files in non-directories into fs.ErrNotExist. See Issue 18984.
+func mapDirOpenError(originalErr error, name string) error {
+ if os.IsNotExist(originalErr) || os.IsPermission(originalErr) {
+ return originalErr
+ }
+
+ parts := strings.Split(name, string(filepath.Separator))
+ for i := range parts {
+ if parts[i] == "" {
+ continue
+ }
+ fi, err := os.Stat(strings.Join(parts[:i+1], string(filepath.Separator)))
+ if err != nil {
+ return originalErr
+ }
+ if !fi.IsDir() {
+ return fs.ErrNotExist
+ }
+ }
+ return originalErr
+}
+
+// Open implements FileSystem using os.Open, opening files for reading rooted
+// and relative to the directory d.
+func (d Dir) Open(name string) (File, error) {
+ if filepath.Separator != '/' && strings.ContainsRune(name, filepath.Separator) {
+ return nil, errors.New("http: invalid character in file path")
+ }
+ dir := string(d)
+ if dir == "" {
+ dir = "."
+ }
+ fullName := filepath.Join(dir, filepath.FromSlash(path.Clean("/"+name)))
+ f, err := os.Open(fullName)
+ if err != nil {
+ return nil, mapDirOpenError(err, fullName)
+ }
+ return f, nil
+}
+
+// A FileSystem implements access to a collection of named files.
+// The elements in a file path are separated by slash ('/', U+002F)
+// characters, regardless of host operating system convention.
+// See the FileServer function to convert a FileSystem to a Handler.
+//
+// This interface predates the fs.FS interface, which can be used instead:
+// the FS adapter function converts an fs.FS to a FileSystem.
+type FileSystem interface {
+ Open(name string) (File, error)
+}
+
+// A File is returned by a FileSystem's Open method and can be
+// served by the FileServer implementation.
+//
+// The methods should behave the same as those on an *os.File.
+type File interface {
+ io.Closer
+ io.Reader
+ io.Seeker
+ Readdir(count int) ([]fs.FileInfo, error)
+ Stat() (fs.FileInfo, error)
+}
+
+type anyDirs interface {
+ len() int
+ name(i int) string
+ isDir(i int) bool
+}
+
+type fileInfoDirs []fs.FileInfo
+
+func (d fileInfoDirs) len() int { return len(d) }
+func (d fileInfoDirs) isDir(i int) bool { return d[i].IsDir() }
+func (d fileInfoDirs) name(i int) string { return d[i].Name() }
+
+type dirEntryDirs []fs.DirEntry
+
+func (d dirEntryDirs) len() int { return len(d) }
+func (d dirEntryDirs) isDir(i int) bool { return d[i].IsDir() }
+func (d dirEntryDirs) name(i int) string { return d[i].Name() }
+
+func dirList(w ResponseWriter, r *Request, f File) {
+ // Prefer to use ReadDir instead of Readdir,
+ // because the former doesn't require calling
+ // Stat on every entry of a directory on Unix.
+ var dirs anyDirs
+ var err error
+ if d, ok := f.(fs.ReadDirFile); ok {
+ var list dirEntryDirs
+ list, err = d.ReadDir(-1)
+ dirs = list
+ } else {
+ var list fileInfoDirs
+ list, err = f.Readdir(-1)
+ dirs = list
+ }
+
+ if err != nil {
+ logf(r, "http: error reading directory: %v", err)
+ Error(w, "Error reading directory", StatusInternalServerError)
+ return
+ }
+ sort.Slice(dirs, func(i, j int) bool { return dirs.name(i) < dirs.name(j) })
+
+ w.Header().Set("Content-Type", "text/html; charset=utf-8")
+ fmt.Fprintf(w, "<pre>\n")
+ for i, n := 0, dirs.len(); i < n; i++ {
+ name := dirs.name(i)
+ if dirs.isDir(i) {
+ name += "/"
+ }
+ // name may contain '?' or '#', which must be escaped to remain
+ // part of the URL path, and not indicate the start of a query
+ // string or fragment.
+ url := url.URL{Path: name}
+ fmt.Fprintf(w, "<a href=\"%s\">%s</a>\n", url.String(), htmlReplacer.Replace(name))
+ }
+ fmt.Fprintf(w, "</pre>\n")
+}
+
+// ServeContent replies to the request using the content in the
+// provided ReadSeeker. The main benefit of ServeContent over io.Copy
+// is that it handles Range requests properly, sets the MIME type, and
+// handles If-Match, If-Unmodified-Since, If-None-Match, If-Modified-Since,
+// and If-Range requests.
+//
+// If the response's Content-Type header is not set, ServeContent
+// first tries to deduce the type from name's file extension and,
+// if that fails, falls back to reading the first block of the content
+// and passing it to DetectContentType.
+// The name is otherwise unused; in particular it can be empty and is
+// never sent in the response.
+//
+// If modtime is not the zero time or Unix epoch, ServeContent
+// includes it in a Last-Modified header in the response. If the
+// request includes an If-Modified-Since header, ServeContent uses
+// modtime to decide whether the content needs to be sent at all.
+//
+// The content's Seek method must work: ServeContent uses
+// a seek to the end of the content to determine its size.
+//
+// If the caller has set w's ETag header formatted per RFC 7232, section 2.3,
+// ServeContent uses it to handle requests using If-Match, If-None-Match, or If-Range.
+//
+// Note that *os.File implements the io.ReadSeeker interface.
+func ServeContent(w ResponseWriter, req *Request, name string, modtime time.Time, content io.ReadSeeker) {
+ sizeFunc := func() (int64, error) {
+ size, err := content.Seek(0, io.SeekEnd)
+ if err != nil {
+ return 0, errSeeker
+ }
+ _, err = content.Seek(0, io.SeekStart)
+ if err != nil {
+ return 0, errSeeker
+ }
+ return size, nil
+ }
+ serveContent(w, req, name, modtime, sizeFunc, content)
+}
+
+// errSeeker is returned by ServeContent's sizeFunc when the content
+// doesn't seek properly. The underlying Seeker's error text isn't
+// included in the sizeFunc reply so it's not sent over HTTP to end
+// users.
+var errSeeker = errors.New("seeker can't seek")
+
+// errNoOverlap is returned by serveContent's parseRange if first-byte-pos of
+// all of the byte-range-spec values is greater than the content size.
+var errNoOverlap = errors.New("invalid range: failed to overlap")
+
+// if name is empty, filename is unknown. (used for mime type, before sniffing)
+// if modtime.IsZero(), modtime is unknown.
+// content must be seeked to the beginning of the file.
+// The sizeFunc is called at most once. Its error, if any, is sent in the HTTP response.
+func serveContent(w ResponseWriter, r *Request, name string, modtime time.Time, sizeFunc func() (int64, error), content io.ReadSeeker) {
+ setLastModified(w, modtime)
+ done, rangeReq := checkPreconditions(w, r, modtime)
+ if done {
+ return
+ }
+
+ code := StatusOK
+
+ // If Content-Type isn't set, use the file's extension to find it, but
+ // if the Content-Type is unset explicitly, do not sniff the type.
+ ctypes, haveType := w.Header()["Content-Type"]
+ var ctype string
+ if !haveType {
+ ctype = mime.TypeByExtension(filepath.Ext(name))
+ if ctype == "" {
+ // read a chunk to decide between utf-8 text and binary
+ var buf [sniffLen]byte
+ n, _ := io.ReadFull(content, buf[:])
+ ctype = DetectContentType(buf[:n])
+ _, err := content.Seek(0, io.SeekStart) // rewind to output whole file
+ if err != nil {
+ Error(w, "seeker can't seek", StatusInternalServerError)
+ return
+ }
+ }
+ w.Header().Set("Content-Type", ctype)
+ } else if len(ctypes) > 0 {
+ ctype = ctypes[0]
+ }
+
+ size, err := sizeFunc()
+ if err != nil {
+ Error(w, err.Error(), StatusInternalServerError)
+ return
+ }
+
+ // handle Content-Range header.
+ sendSize := size
+ var sendContent io.Reader = content
+ if size >= 0 {
+ ranges, err := parseRange(rangeReq, size)
+ if err != nil {
+ if err == errNoOverlap {
+ w.Header().Set("Content-Range", fmt.Sprintf("bytes */%d", size))
+ }
+ Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
+ return
+ }
+ if sumRangesSize(ranges) > size {
+ // The total number of bytes in all the ranges
+ // is larger than the size of the file by
+ // itself, so this is probably an attack, or a
+ // dumb client. Ignore the range request.
+ ranges = nil
+ }
+ switch {
+ case len(ranges) == 1:
+ // RFC 7233, Section 4.1:
+ // "If a single part is being transferred, the server
+ // generating the 206 response MUST generate a
+ // Content-Range header field, describing what range
+ // of the selected representation is enclosed, and a
+ // payload consisting of the range.
+ // ...
+ // A server MUST NOT generate a multipart response to
+ // a request for a single range, since a client that
+ // does not request multiple parts might not support
+ // multipart responses."
+ ra := ranges[0]
+ if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
+ Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
+ return
+ }
+ sendSize = ra.length
+ code = StatusPartialContent
+ w.Header().Set("Content-Range", ra.contentRange(size))
+ case len(ranges) > 1:
+ sendSize = rangesMIMESize(ranges, ctype, size)
+ code = StatusPartialContent
+
+ pr, pw := io.Pipe()
+ mw := multipart.NewWriter(pw)
+ w.Header().Set("Content-Type", "multipart/byteranges; boundary="+mw.Boundary())
+ sendContent = pr
+ defer pr.Close() // cause writing goroutine to fail and exit if CopyN doesn't finish.
+ go func() {
+ for _, ra := range ranges {
+ part, err := mw.CreatePart(ra.mimeHeader(ctype, size))
+ if err != nil {
+ pw.CloseWithError(err)
+ return
+ }
+ if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
+ pw.CloseWithError(err)
+ return
+ }
+ if _, err := io.CopyN(part, content, ra.length); err != nil {
+ pw.CloseWithError(err)
+ return
+ }
+ }
+ mw.Close()
+ pw.Close()
+ }()
+ }
+
+ w.Header().Set("Accept-Ranges", "bytes")
+ if w.Header().Get("Content-Encoding") == "" {
+ w.Header().Set("Content-Length", strconv.FormatInt(sendSize, 10))
+ }
+ }
+
+ w.WriteHeader(code)
+
+ if r.Method != "HEAD" {
+ io.CopyN(w, sendContent, sendSize)
+ }
+}
+
+// scanETag determines if a syntactically valid ETag is present at s. If so,
+// the ETag and remaining text after consuming ETag is returned. Otherwise,
+// it returns "", "".
+func scanETag(s string) (etag string, remain string) {
+ s = textproto.TrimString(s)
+ start := 0
+ if strings.HasPrefix(s, "W/") {
+ start = 2
+ }
+ if len(s[start:]) < 2 || s[start] != '"' {
+ return "", ""
+ }
+ // ETag is either W/"text" or "text".
+ // See RFC 7232 2.3.
+ for i := start + 1; i < len(s); i++ {
+ c := s[i]
+ switch {
+ // Character values allowed in ETags.
+ case c == 0x21 || c >= 0x23 && c <= 0x7E || c >= 0x80:
+ case c == '"':
+ return s[:i+1], s[i+1:]
+ default:
+ return "", ""
+ }
+ }
+ return "", ""
+}
+
+// etagStrongMatch reports whether a and b match using strong ETag comparison.
+// Assumes a and b are valid ETags.
+func etagStrongMatch(a, b string) bool {
+ return a == b && a != "" && a[0] == '"'
+}
+
+// etagWeakMatch reports whether a and b match using weak ETag comparison.
+// Assumes a and b are valid ETags.
+func etagWeakMatch(a, b string) bool {
+ return strings.TrimPrefix(a, "W/") == strings.TrimPrefix(b, "W/")
+}
+
+// condResult is the result of an HTTP request precondition check.
+// See https://tools.ietf.org/html/rfc7232 section 3.
+type condResult int
+
+const (
+ condNone condResult = iota
+ condTrue
+ condFalse
+)
+
+func checkIfMatch(w ResponseWriter, r *Request) condResult {
+ im := r.Header.Get("If-Match")
+ if im == "" {
+ return condNone
+ }
+ for {
+ im = textproto.TrimString(im)
+ if len(im) == 0 {
+ break
+ }
+ if im[0] == ',' {
+ im = im[1:]
+ continue
+ }
+ if im[0] == '*' {
+ return condTrue
+ }
+ etag, remain := scanETag(im)
+ if etag == "" {
+ break
+ }
+ if etagStrongMatch(etag, w.Header().get("Etag")) {
+ return condTrue
+ }
+ im = remain
+ }
+
+ return condFalse
+}
+
+func checkIfUnmodifiedSince(r *Request, modtime time.Time) condResult {
+ ius := r.Header.Get("If-Unmodified-Since")
+ if ius == "" || isZeroTime(modtime) {
+ return condNone
+ }
+ t, err := ParseTime(ius)
+ if err != nil {
+ return condNone
+ }
+
+ // The Last-Modified header truncates sub-second precision so
+ // the modtime needs to be truncated too.
+ modtime = modtime.Truncate(time.Second)
+ if modtime.Before(t) || modtime.Equal(t) {
+ return condTrue
+ }
+ return condFalse
+}
+
+func checkIfNoneMatch(w ResponseWriter, r *Request) condResult {
+ inm := r.Header.get("If-None-Match")
+ if inm == "" {
+ return condNone
+ }
+ buf := inm
+ for {
+ buf = textproto.TrimString(buf)
+ if len(buf) == 0 {
+ break
+ }
+ if buf[0] == ',' {
+ buf = buf[1:]
+ continue
+ }
+ if buf[0] == '*' {
+ return condFalse
+ }
+ etag, remain := scanETag(buf)
+ if etag == "" {
+ break
+ }
+ if etagWeakMatch(etag, w.Header().get("Etag")) {
+ return condFalse
+ }
+ buf = remain
+ }
+ return condTrue
+}
+
+func checkIfModifiedSince(r *Request, modtime time.Time) condResult {
+ if r.Method != "GET" && r.Method != "HEAD" {
+ return condNone
+ }
+ ims := r.Header.Get("If-Modified-Since")
+ if ims == "" || isZeroTime(modtime) {
+ return condNone
+ }
+ t, err := ParseTime(ims)
+ if err != nil {
+ return condNone
+ }
+ // The Last-Modified header truncates sub-second precision so
+ // the modtime needs to be truncated too.
+ modtime = modtime.Truncate(time.Second)
+ if modtime.Before(t) || modtime.Equal(t) {
+ return condFalse
+ }
+ return condTrue
+}
+
+func checkIfRange(w ResponseWriter, r *Request, modtime time.Time) condResult {
+ if r.Method != "GET" && r.Method != "HEAD" {
+ return condNone
+ }
+ ir := r.Header.get("If-Range")
+ if ir == "" {
+ return condNone
+ }
+ etag, _ := scanETag(ir)
+ if etag != "" {
+ if etagStrongMatch(etag, w.Header().Get("Etag")) {
+ return condTrue
+ } else {
+ return condFalse
+ }
+ }
+ // The If-Range value is typically the ETag value, but it may also be
+ // the modtime date. See golang.org/issue/8367.
+ if modtime.IsZero() {
+ return condFalse
+ }
+ t, err := ParseTime(ir)
+ if err != nil {
+ return condFalse
+ }
+ if t.Unix() == modtime.Unix() {
+ return condTrue
+ }
+ return condFalse
+}
+
+var unixEpochTime = time.Unix(0, 0)
+
+// isZeroTime reports whether t is obviously unspecified (either zero or Unix()=0).
+func isZeroTime(t time.Time) bool {
+ return t.IsZero() || t.Equal(unixEpochTime)
+}
+
+func setLastModified(w ResponseWriter, modtime time.Time) {
+ if !isZeroTime(modtime) {
+ w.Header().Set("Last-Modified", modtime.UTC().Format(TimeFormat))
+ }
+}
+
+func writeNotModified(w ResponseWriter) {
+ // RFC 7232 section 4.1:
+ // a sender SHOULD NOT generate representation metadata other than the
+ // above listed fields unless said metadata exists for the purpose of
+ // guiding cache updates (e.g., Last-Modified might be useful if the
+ // response does not have an ETag field).
+ h := w.Header()
+ delete(h, "Content-Type")
+ delete(h, "Content-Length")
+ if h.Get("Etag") != "" {
+ delete(h, "Last-Modified")
+ }
+ w.WriteHeader(StatusNotModified)
+}
+
+// checkPreconditions evaluates request preconditions and reports whether a precondition
+// resulted in sending StatusNotModified or StatusPreconditionFailed.
+func checkPreconditions(w ResponseWriter, r *Request, modtime time.Time) (done bool, rangeHeader string) {
+ // This function carefully follows RFC 7232 section 6.
+ ch := checkIfMatch(w, r)
+ if ch == condNone {
+ ch = checkIfUnmodifiedSince(r, modtime)
+ }
+ if ch == condFalse {
+ w.WriteHeader(StatusPreconditionFailed)
+ return true, ""
+ }
+ switch checkIfNoneMatch(w, r) {
+ case condFalse:
+ if r.Method == "GET" || r.Method == "HEAD" {
+ writeNotModified(w)
+ return true, ""
+ } else {
+ w.WriteHeader(StatusPreconditionFailed)
+ return true, ""
+ }
+ case condNone:
+ if checkIfModifiedSince(r, modtime) == condFalse {
+ writeNotModified(w)
+ return true, ""
+ }
+ }
+
+ rangeHeader = r.Header.get("Range")
+ if rangeHeader != "" && checkIfRange(w, r, modtime) == condFalse {
+ rangeHeader = ""
+ }
+ return false, rangeHeader
+}
+
+// name is '/'-separated, not filepath.Separator.
+func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirect bool) {
+ const indexPage = "/index.html"
+
+ // redirect .../index.html to .../
+ // can't use Redirect() because that would make the path absolute,
+ // which would be a problem running under StripPrefix
+ if strings.HasSuffix(r.URL.Path, indexPage) {
+ localRedirect(w, r, "./")
+ return
+ }
+
+ f, err := fs.Open(name)
+ if err != nil {
+ msg, code := toHTTPError(err)
+ Error(w, msg, code)
+ return
+ }
+ defer f.Close()
+
+ d, err := f.Stat()
+ if err != nil {
+ msg, code := toHTTPError(err)
+ Error(w, msg, code)
+ return
+ }
+
+ if redirect {
+ // redirect to canonical path: / at end of directory url
+ // r.URL.Path always begins with /
+ url := r.URL.Path
+ if d.IsDir() {
+ if url[len(url)-1] != '/' {
+ localRedirect(w, r, path.Base(url)+"/")
+ return
+ }
+ } else {
+ if url[len(url)-1] == '/' {
+ localRedirect(w, r, "../"+path.Base(url))
+ return
+ }
+ }
+ }
+
+ if d.IsDir() {
+ url := r.URL.Path
+ // redirect if the directory name doesn't end in a slash
+ if url == "" || url[len(url)-1] != '/' {
+ localRedirect(w, r, path.Base(url)+"/")
+ return
+ }
+
+ // use contents of index.html for directory, if present
+ index := strings.TrimSuffix(name, "/") + indexPage
+ ff, err := fs.Open(index)
+ if err == nil {
+ defer ff.Close()
+ dd, err := ff.Stat()
+ if err == nil {
+ name = index
+ d = dd
+ f = ff
+ }
+ }
+ }
+
+ // Still a directory? (we didn't find an index.html file)
+ if d.IsDir() {
+ if checkIfModifiedSince(r, d.ModTime()) == condFalse {
+ writeNotModified(w)
+ return
+ }
+ setLastModified(w, d.ModTime())
+ dirList(w, r, f)
+ return
+ }
+
+ // serveContent will check modification time
+ sizeFunc := func() (int64, error) { return d.Size(), nil }
+ serveContent(w, r, d.Name(), d.ModTime(), sizeFunc, f)
+}
+
+// toHTTPError returns a non-specific HTTP error message and status code
+// for a given non-nil error value. It's important that toHTTPError does not
+// actually return err.Error(), since msg and httpStatus are returned to users,
+// and historically Go's ServeContent always returned just "404 Not Found" for
+// all errors. We don't want to start leaking information in error messages.
+func toHTTPError(err error) (msg string, httpStatus int) {
+ if os.IsNotExist(err) {
+ return "404 page not found", StatusNotFound
+ }
+ if os.IsPermission(err) {
+ return "403 Forbidden", StatusForbidden
+ }
+ // Default:
+ return "500 Internal Server Error", StatusInternalServerError
+}
+
+// localRedirect gives a Moved Permanently response.
+// It does not convert relative paths to absolute paths like Redirect does.
+func localRedirect(w ResponseWriter, r *Request, newPath string) {
+ if q := r.URL.RawQuery; q != "" {
+ newPath += "?" + q
+ }
+ w.Header().Set("Location", newPath)
+ w.WriteHeader(StatusMovedPermanently)
+}
+
+// ServeFile replies to the request with the contents of the named
+// file or directory.
+//
+// If the provided file or directory name is a relative path, it is
+// interpreted relative to the current directory and may ascend to
+// parent directories. If the provided name is constructed from user
+// input, it should be sanitized before calling ServeFile.
+//
+// As a precaution, ServeFile will reject requests where r.URL.Path
+// contains a ".." path element; this protects against callers who
+// might unsafely use filepath.Join on r.URL.Path without sanitizing
+// it and then use that filepath.Join result as the name argument.
+//
+// As another special case, ServeFile redirects any request where r.URL.Path
+// ends in "/index.html" to the same path, without the final
+// "index.html". To avoid such redirects either modify the path or
+// use ServeContent.
+//
+// Outside of those two special cases, ServeFile does not use
+// r.URL.Path for selecting the file or directory to serve; only the
+// file or directory provided in the name argument is used.
+func ServeFile(w ResponseWriter, r *Request, name string) {
+ if containsDotDot(r.URL.Path) {
+ // Too many programs use r.URL.Path to construct the argument to
+ // serveFile. Reject the request under the assumption that happened
+ // here and ".." may not be wanted.
+ // Note that name might not contain "..", for example if code (still
+ // incorrectly) used filepath.Join(myDir, r.URL.Path).
+ Error(w, "invalid URL path", StatusBadRequest)
+ return
+ }
+ dir, file := filepath.Split(name)
+ serveFile(w, r, Dir(dir), file, false)
+}
+
+func containsDotDot(v string) bool {
+ if !strings.Contains(v, "..") {
+ return false
+ }
+ for _, ent := range strings.FieldsFunc(v, isSlashRune) {
+ if ent == ".." {
+ return true
+ }
+ }
+ return false
+}
+
+func isSlashRune(r rune) bool { return r == '/' || r == '\\' }
+
+type fileHandler struct {
+ root FileSystem
+}
+
+type ioFS struct {
+ fsys fs.FS
+}
+
+type ioFile struct {
+ file fs.File
+}
+
+func (f ioFS) Open(name string) (File, error) {
+ if name == "/" {
+ name = "."
+ } else {
+ name = strings.TrimPrefix(name, "/")
+ }
+ file, err := f.fsys.Open(name)
+ if err != nil {
+ return nil, err
+ }
+ return ioFile{file}, nil
+}
+
+func (f ioFile) Close() error { return f.file.Close() }
+func (f ioFile) Read(b []byte) (int, error) { return f.file.Read(b) }
+func (f ioFile) Stat() (fs.FileInfo, error) { return f.file.Stat() }
+
+var errMissingSeek = errors.New("io.File missing Seek method")
+var errMissingReadDir = errors.New("io.File directory missing ReadDir method")
+
+func (f ioFile) Seek(offset int64, whence int) (int64, error) {
+ s, ok := f.file.(io.Seeker)
+ if !ok {
+ return 0, errMissingSeek
+ }
+ return s.Seek(offset, whence)
+}
+
+func (f ioFile) ReadDir(count int) ([]fs.DirEntry, error) {
+ d, ok := f.file.(fs.ReadDirFile)
+ if !ok {
+ return nil, errMissingReadDir
+ }
+ return d.ReadDir(count)
+}
+
+func (f ioFile) Readdir(count int) ([]fs.FileInfo, error) {
+ d, ok := f.file.(fs.ReadDirFile)
+ if !ok {
+ return nil, errMissingReadDir
+ }
+ var list []fs.FileInfo
+ for {
+ dirs, err := d.ReadDir(count - len(list))
+ for _, dir := range dirs {
+ info, err := dir.Info()
+ if err != nil {
+ // Pretend it doesn't exist, like (*os.File).Readdir does.
+ continue
+ }
+ list = append(list, info)
+ }
+ if err != nil {
+ return list, err
+ }
+ if count < 0 || len(list) >= count {
+ break
+ }
+ }
+ return list, nil
+}
+
+// FS converts fsys to a FileSystem implementation,
+// for use with FileServer and NewFileTransport.
+func FS(fsys fs.FS) FileSystem {
+ return ioFS{fsys}
+}
+
+// FileServer returns a handler that serves HTTP requests
+// with the contents of the file system rooted at root.
+//
+// As a special case, the returned file server redirects any request
+// ending in "/index.html" to the same path, without the final
+// "index.html".
+//
+// To use the operating system's file system implementation,
+// use http.Dir:
+//
+// http.Handle("/", http.FileServer(http.Dir("/tmp")))
+//
+// To use an fs.FS implementation, use http.FS to convert it:
+//
+// http.Handle("/", http.FileServer(http.FS(fsys)))
+//
+func FileServer(root FileSystem) Handler {
+ return &fileHandler{root}
+}
+
+func (f *fileHandler) ServeHTTP(w ResponseWriter, r *Request) {
+ upath := r.URL.Path
+ if !strings.HasPrefix(upath, "/") {
+ upath = "/" + upath
+ r.URL.Path = upath
+ }
+ serveFile(w, r, f.root, path.Clean(upath), true)
+}
+
+// httpRange specifies the byte range to be sent to the client.
+type httpRange struct {
+ start, length int64
+}
+
+func (r httpRange) contentRange(size int64) string {
+ return fmt.Sprintf("bytes %d-%d/%d", r.start, r.start+r.length-1, size)
+}
+
+func (r httpRange) mimeHeader(contentType string, size int64) textproto.MIMEHeader {
+ return textproto.MIMEHeader{
+ "Content-Range": {r.contentRange(size)},
+ "Content-Type": {contentType},
+ }
+}
+
+// parseRange parses a Range header string as per RFC 7233.
+// errNoOverlap is returned if none of the ranges overlap.
+func parseRange(s string, size int64) ([]httpRange, error) {
+ if s == "" {
+ return nil, nil // header not present
+ }
+ const b = "bytes="
+ if !strings.HasPrefix(s, b) {
+ return nil, errors.New("invalid range")
+ }
+ var ranges []httpRange
+ noOverlap := false
+ for _, ra := range strings.Split(s[len(b):], ",") {
+ ra = textproto.TrimString(ra)
+ if ra == "" {
+ continue
+ }
+ i := strings.Index(ra, "-")
+ if i < 0 {
+ return nil, errors.New("invalid range")
+ }
+ start, end := textproto.TrimString(ra[:i]), textproto.TrimString(ra[i+1:])
+ var r httpRange
+ if start == "" {
+ // If no start is specified, end specifies the
+ // range start relative to the end of the file,
+ // and we are dealing with <suffix-length>
+ // which has to be a non-negative integer as per
+ // RFC 7233 Section 2.1 "Byte-Ranges".
+ if end == "" || end[0] == '-' {
+ return nil, errors.New("invalid range")
+ }
+ i, err := strconv.ParseInt(end, 10, 64)
+ if i < 0 || err != nil {
+ return nil, errors.New("invalid range")
+ }
+ if i > size {
+ i = size
+ }
+ r.start = size - i
+ r.length = size - r.start
+ } else {
+ i, err := strconv.ParseInt(start, 10, 64)
+ if err != nil || i < 0 {
+ return nil, errors.New("invalid range")
+ }
+ if i >= size {
+ // If the range begins after the size of the content,
+ // then it does not overlap.
+ noOverlap = true
+ continue
+ }
+ r.start = i
+ if end == "" {
+ // If no end is specified, range extends to end of the file.
+ r.length = size - r.start
+ } else {
+ i, err := strconv.ParseInt(end, 10, 64)
+ if err != nil || r.start > i {
+ return nil, errors.New("invalid range")
+ }
+ if i >= size {
+ i = size - 1
+ }
+ r.length = i - r.start + 1
+ }
+ }
+ ranges = append(ranges, r)
+ }
+ if noOverlap && len(ranges) == 0 {
+ // The specified ranges did not overlap with the content.
+ return nil, errNoOverlap
+ }
+ return ranges, nil
+}
+
+// countingWriter counts how many bytes have been written to it.
+type countingWriter int64
+
+func (w *countingWriter) Write(p []byte) (n int, err error) {
+ *w += countingWriter(len(p))
+ return len(p), nil
+}
+
+// rangesMIMESize returns the number of bytes it takes to encode the
+// provided ranges as a multipart response.
+func rangesMIMESize(ranges []httpRange, contentType string, contentSize int64) (encSize int64) {
+ var w countingWriter
+ mw := multipart.NewWriter(&w)
+ for _, ra := range ranges {
+ mw.CreatePart(ra.mimeHeader(contentType, contentSize))
+ encSize += ra.length
+ }
+ mw.Close()
+ encSize += int64(w)
+ return
+}
+
+func sumRangesSize(ranges []httpRange) (size int64) {
+ for _, ra := range ranges {
+ size += ra.length
+ }
+ return
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-15 16:13:11 +0000