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// +build go1.16
package gemini
import (
"context"
"errors"
"fmt"
"io"
"io/fs"
"mime"
"net/url"
"path"
"sort"
"strings"
)
// FileServer returns a handler that serves Gemini requests with the contents
// of the provided file system.
//
// To use the operating system's file system implementation, use os.DirFS:
//
// gemini.FileServer(os.DirFS("/tmp"))
func FileServer(fsys fs.FS) Handler {
return fileServer{fsys}
}
type fileServer struct {
fs.FS
}
func (fsys fileServer) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
const indexPage = "/index.gmi"
url := path.Clean(r.URL.Path)
// Redirect .../index.gmi to .../
if strings.HasSuffix(url, indexPage) {
w.WriteHeader(StatusPermanentRedirect, strings.TrimSuffix(url, "index.gmi"))
return
}
name := url
if name == "/" {
name = "."
} else {
name = strings.TrimPrefix(name, "/")
}
f, err := fsys.Open(name)
if err != nil {
w.WriteHeader(toGeminiError(err))
return
}
defer f.Close()
stat, err := f.Stat()
if err != nil {
w.WriteHeader(toGeminiError(err))
return
}
// Redirect to canonical path
if len(r.URL.Path) != 0 {
if stat.IsDir() {
target := url
if target != "/" {
target += "/"
}
if len(r.URL.Path) != len(target) || r.URL.Path != target {
w.WriteHeader(StatusPermanentRedirect, target)
return
}
} else if r.URL.Path[len(r.URL.Path)-1] == '/' {
// Remove trailing slash
w.WriteHeader(StatusPermanentRedirect, url)
return
}
}
if stat.IsDir() {
// Use contents of index.gmi if present
name = path.Join(name, indexPage)
index, err := fsys.Open(name)
if err == nil {
defer index.Close()
f = index
} else {
// Failed to find index file
dirList(w, f)
return
}
}
// Detect mimetype from file extension
ext := path.Ext(name)
mimetype := mime.TypeByExtension(ext)
w.SetMediaType(mimetype)
io.Copy(w, f)
}
// ServeFile responds to the request with the contents of the named file
// or directory. If the provided name is constructed from user input, it
// should be sanitized before calling ServeFile.
func ServeFile(w ResponseWriter, fsys fs.FS, name string) {
const indexPage = "/index.gmi"
// Ensure name is relative
if name == "/" {
name = "."
} else {
name = strings.TrimLeft(name, "/")
}
f, err := fsys.Open(name)
if err != nil {
w.WriteHeader(toGeminiError(err))
return
}
defer f.Close()
stat, err := f.Stat()
if err != nil {
w.WriteHeader(toGeminiError(err))
return
}
if stat.IsDir() {
// Use contents of index file if present
name = path.Join(name, indexPage)
index, err := fsys.Open(name)
if err == nil {
defer index.Close()
f = index
} else {
// Failed to find index file
dirList(w, f)
return
}
}
// Detect mimetype from file extension
ext := path.Ext(name)
mimetype := mime.TypeByExtension(ext)
w.SetMediaType(mimetype)
io.Copy(w, f)
}
func dirList(w ResponseWriter, f fs.File) {
var entries []fs.DirEntry
var err error
d, ok := f.(fs.ReadDirFile)
if ok {
entries, err = d.ReadDir(-1)
}
if !ok || err != nil {
w.WriteHeader(StatusTemporaryFailure, "Error reading directory")
return
}
sort.Slice(entries, func(i, j int) bool {
return entries[i].Name() < entries[j].Name()
})
for _, entry := range entries {
name := entry.Name()
if entry.IsDir() {
name += "/"
}
link := LineLink{
Name: name,
URL: (&url.URL{Path: name}).EscapedPath(),
}
fmt.Fprintln(w, link.String())
}
}
func toGeminiError(err error) (status Status, meta string) {
if errors.Is(err, fs.ErrNotExist) {
return StatusNotFound, "Not found"
}
if errors.Is(err, fs.ErrPermission) {
return StatusNotFound, "Forbidden"
}
return StatusTemporaryFailure, "Internal server error"
}
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