102 lines
2.7 KiB
Go
102 lines
2.7 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package dirfs provides a webdav.FileSystem that looks like a read-only
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// directory containing only subdirectories.
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package dirfs
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import (
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"slices"
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"strings"
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"time"
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"tailscale.com/tailfs/tailfsimpl/shared"
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"tailscale.com/tstime"
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)
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// Child is subdirectory of an FS.
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type Child struct {
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// Name is the name of the child
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Name string
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// Available is a function indicating whether or not the child is currently
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// available. Unavailable children are excluded from the FS's directory
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// listing. Available must be safe for concurrent use.
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Available func() bool
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}
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func (c *Child) isAvailable() bool {
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if c.Available == nil {
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return true
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}
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return c.Available()
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}
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// FS is a read-only webdav.FileSystem that is composed of multiple child
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// folders.
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//
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// When listing the contents of this FileSystem's root directory, children will
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// be ordered in the order they're given to the FS.
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//
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// Children in an FS cannot be added, removed or renamed via operations on the
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// webdav.FileSystem interface like filesystem.Mkdir or filesystem.OpenFile.
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//
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// Any attempts to perform operations on paths inside of children will result
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// in a panic, as these are not expected to be performed on this FS.
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//
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// An FS an optionally have a StaticRoot, which will insert a folder with that
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// StaticRoot into the tree, like this:
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//
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// -- <StaticRoot>
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// ----- <Child>
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// ----- <Child>
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type FS struct {
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// Children configures the full set of children of this FS.
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Children []*Child
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// Clock, if given, will cause this FS to use Clock.now() as the current
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// time.
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Clock tstime.Clock
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// StaticRoot, if given, will insert the given name as a static root into
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// every path.
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StaticRoot string
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}
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func (dfs *FS) findChild(name string) (int, *Child) {
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var child *Child
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i, found := slices.BinarySearchFunc(dfs.Children, name, func(child *Child, name string) int {
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return strings.Compare(child.Name, name)
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})
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if found {
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child = dfs.Children[i]
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}
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return i, child
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}
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// childFor returns the child for the given filename. If the filename refers to
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// a path inside of a child, this will panic.
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func (dfs *FS) childFor(name string) *Child {
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pathComponents := shared.CleanAndSplit(name)
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if len(pathComponents) != 1 {
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panic("dirfs does not permit reaching into child directories")
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}
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_, child := dfs.findChild(pathComponents[0])
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return child
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}
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func (dfs *FS) now() time.Time {
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if dfs.Clock != nil {
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return dfs.Clock.Now()
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}
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return time.Now()
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}
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func (dfs *FS) trimStaticRoot(name string) (string, bool) {
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before, after, found := strings.Cut(name, "/"+dfs.StaticRoot)
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if !found {
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return before, false
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}
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return after, shared.IsRoot(after)
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}
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