154 lines
4.7 KiB
Go
154 lines
4.7 KiB
Go
// Copyright 2015 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package fuse
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import (
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"fmt"
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"log"
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"runtime"
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"strings"
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"golang.org/x/net/context"
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)
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// Optional configuration accepted by Mount.
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type MountConfig struct {
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// The context from which every op read from the connetion by the sever
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// should inherit. If nil, context.Background() will be used.
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OpContext context.Context
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// If non-empty, the name of the file system as displayed by e.g. `mount`.
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// This is important because the `umount` command requires root privileges if
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// it doesn't agree with /etc/fstab.
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FSName string
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// Mount the file system in read-only mode. File modes will appear as normal,
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// but opening a file for writing and metadata operations like chmod,
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// chtimes, etc. will fail.
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ReadOnly bool
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// A logger to use for logging errors. All errors are logged, with the
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// exception of a few blacklisted errors that are expected. If nil, no error
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// logging is performed.
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ErrorLogger *log.Logger
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// A logger to use for logging debug information. If nil, no debug logging is
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// performed.
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DebugLogger *log.Logger
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// OS X only.
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//
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// Normally on OS X we mount with the novncache option
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// (cf. http://goo.gl/1pTjuk), which disables entry caching in the kernel.
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// This is because osxfuse does not honor the entry expiration values we
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// return to it, instead caching potentially forever (cf.
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// http://goo.gl/8yR0Ie), and it is probably better to fail to cache than to
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// cache for too long, since the latter is more likely to hide consistency
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// bugs that are difficult to detect and diagnose.
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//
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// This field disables the use of novncache, restoring entry caching. Beware:
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// the value of ChildInodeEntry.EntryExpiration is ignored by the kernel, and
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// entries will be cached for an arbitrarily long time.
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EnableVnodeCaching bool
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// Additional key=value options to pass unadulterated to the underlying mount
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// command. See `man 8 mount`, the fuse documentation, etc. for
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// system-specific information.
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//
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// For expert use only! May invalidate other guarantees made in the
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// documentation for this package.
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Options map[string]string
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}
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// Create a map containing all of the key=value mount options to be given to
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// the mount helper.
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func (c *MountConfig) toMap() (opts map[string]string) {
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isDarwin := runtime.GOOS == "darwin"
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opts = make(map[string]string)
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// Enable permissions checking in the kernel. See the comments on
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// InodeAttributes.Mode.
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opts["default_permissions"] = ""
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// HACK(jacobsa): Work around what appears to be a bug in systemd v219, as
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// shipped in Ubuntu 15.04, where it automatically unmounts any file system
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// that doesn't set an explicit name.
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//
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// When Ubuntu contains systemd v220, this workaround should be removed and
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// the systemd bug reopened if the problem persists.
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//
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// Cf. https://github.com/bazil/fuse/issues/89
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// Cf. https://bugs.freedesktop.org/show_bug.cgi?id=90907
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fsname := c.FSName
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if runtime.GOOS == "linux" && fsname == "" {
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fsname = "some_fuse_file_system"
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}
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// Special file system name?
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if fsname != "" {
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opts["fsname"] = fsname
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}
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// Read only?
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if c.ReadOnly {
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opts["ro"] = ""
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}
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// OS X: set novncache when appropriate.
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if isDarwin && !c.EnableVnodeCaching {
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opts["novncache"] = ""
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}
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// OS X: disable the use of "Apple Double" (._foo and .DS_Store) files, which
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// just add noise to debug output and can have significant cost on
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// network-based file systems.
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//
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// Cf. https://github.com/osxfuse/osxfuse/wiki/Mount-options
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if isDarwin {
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opts["noappledouble"] = ""
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}
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// Last but not least: other user-supplied options.
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for k, v := range c.Options {
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opts[k] = v
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}
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return
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}
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func escapeOptionsKey(s string) (res string) {
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res = s
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res = strings.Replace(res, `\`, `\\`, -1)
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res = strings.Replace(res, `,`, `\,`, -1)
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return
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}
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// Create an options string suitable for passing to the mount helper.
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func (c *MountConfig) toOptionsString() string {
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var components []string
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for k, v := range c.toMap() {
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k = escapeOptionsKey(k)
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component := k
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if v != "" {
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component = fmt.Sprintf("%s=%s", k, v)
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}
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components = append(components, component)
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}
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return strings.Join(components, ",")
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}
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