18947: Refactor keep-web as arvados-server command.

[arvados.git] / services / keep-web / webdav.go

diff --git a/services/keep-web/webdav.go b/services/keep-web/webdav.go
index 87d9c47f1430e9a8c028ff35c0eb2b16e6772d82..501c355a7388a53fe3b40fc3f082c63768665620 100644 (file)
--- a/services/keep-web/webdav.go
+++ b/services/keep-web/webdav.go
@@ -2,18 +2,21 @@
 //
 // SPDX-License-Identifier: AGPL-3.0
 
-package main
+package keepweb
 
 import (
        "crypto/rand"
        "errors"
        "fmt"
+       "io"
        prand "math/rand"
        "os"
+       "path"
+       "strings"
        "sync/atomic"
        "time"
 
-       "git.curoverse.com/arvados.git/sdk/go/arvados"
+       "git.arvados.org/arvados.git/sdk/go/arvados"
 
        "golang.org/x/net/context"
        "golang.org/x/net/webdav"
@@ -27,49 +30,116 @@ var (
 
 // webdavFS implements a webdav.FileSystem by wrapping an
 // arvados.CollectionFilesystem.
+//
+// Collections don't preserve empty directories, so Mkdir is
+// effectively a no-op, and we need to make parent dirs spring into
+// existence automatically so sequences like "mkcol foo; put foo/bar"
+// work as expected.
 type webdavFS struct {
-       collfs arvados.CollectionFileSystem
-       update func() error
+       collfs  arvados.FileSystem
+       writing bool
+       // webdav PROPFIND reads the first few bytes of each file
+       // whose filename extension isn't recognized, which is
+       // prohibitively expensive: we end up fetching multiple 64MiB
+       // blocks. Avoid this by returning EOF on all reads when
+       // handling a PROPFIND.
+       alwaysReadEOF bool
+}
+
+func (fs *webdavFS) makeparents(name string) {
+       if !fs.writing {
+               return
+       }
+       dir, _ := path.Split(name)
+       if dir == "" || dir == "/" {
+               return
+       }
+       dir = dir[:len(dir)-1]
+       fs.makeparents(dir)
+       fs.collfs.Mkdir(dir, 0755)
 }
 
 func (fs *webdavFS) Mkdir(ctx context.Context, name string, perm os.FileMode) error {
+       if !fs.writing {
+               return errReadOnly
+       }
+       name = strings.TrimRight(name, "/")
+       fs.makeparents(name)
        return fs.collfs.Mkdir(name, 0755)
 }
 
 func (fs *webdavFS) OpenFile(ctx context.Context, name string, flag int, perm os.FileMode) (f webdav.File, err error) {
-       writing := flag&(os.O_WRONLY|os.O_RDWR) != 0
-       if writing && fs.update == nil {
-               return nil, errReadOnly
+       writing := flag&(os.O_WRONLY|os.O_RDWR|os.O_TRUNC) != 0
+       if writing {
+               fs.makeparents(name)
        }
        f, err = fs.collfs.OpenFile(name, flag, perm)
-       if writing && err == nil {
-               f = writingFile{File: f, update: fs.update}
+       if !fs.writing {
+               // webdav module returns 404 on all OpenFile errors,
+               // but returns 405 Method Not Allowed if OpenFile()
+               // succeeds but Write() or Close() fails. We'd rather
+               // have 405. writeFailer ensures Close() fails if the
+               // file is opened for writing *or* Write() is called.
+               var err error
+               if writing {
+                       err = errReadOnly
+               }
+               f = writeFailer{File: f, err: err}
+       }
+       if fs.alwaysReadEOF {
+               f = readEOF{File: f}
        }
        return
 }
 
 func (fs *webdavFS) RemoveAll(ctx context.Context, name string) error {
-       return errReadOnly
+       return fs.collfs.RemoveAll(name)
 }
 
 func (fs *webdavFS) Rename(ctx context.Context, oldName, newName string) error {
-       return errReadOnly
+       if !fs.writing {
+               return errReadOnly
+       }
+       if strings.HasSuffix(oldName, "/") {
+               // WebDAV "MOVE foo/ bar/" means rename foo to bar.
+               oldName = oldName[:len(oldName)-1]
+               newName = strings.TrimSuffix(newName, "/")
+       }
+       fs.makeparents(newName)
+       return fs.collfs.Rename(oldName, newName)
 }
 
 func (fs *webdavFS) Stat(ctx context.Context, name string) (os.FileInfo, error) {
+       if fs.writing {
+               fs.makeparents(name)
+       }
        return fs.collfs.Stat(name)
 }
 
-type writingFile struct {
+type writeFailer struct {
        webdav.File
-       update func() error
+       err error
+}
+
+func (wf writeFailer) Write([]byte) (int, error) {
+       wf.err = errReadOnly
+       return 0, wf.err
 }
 
-func (f writingFile) Close() error {
-       if err := f.File.Close(); err != nil || f.update == nil {
-               return err
+func (wf writeFailer) Close() error {
+       err := wf.File.Close()
+       if err != nil {
+               wf.err = err
        }
-       return f.update()
+       return wf.err
+}
+
+type readEOF struct {
+       webdav.File
+}
+
+func (readEOF) Read(p []byte) (int, error) {
+       return 0, io.EOF
 }
 
 // noLockSystem implements webdav.LockSystem by returning success for