fuchsia_fatfs/
node.rs

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1// Copyright 2020 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use crate::directory::FatDirectory;
6use crate::file::FatFile;
7use crate::filesystem::{FatFilesystem, FatFilesystemInner};
8use std::ops::Deref;
9use std::sync::{Arc, Weak};
10use zx::Status;
11
12pub trait Node {
13    /// Attach this FatNode to the given FatDirectory, with the given name.
14    fn attach(
15        &self,
16        parent: Arc<FatDirectory>,
17        name: &str,
18        fs: &FatFilesystemInner,
19    ) -> Result<(), Status>;
20
21    /// Detach this FatNode from its parent.
22    fn detach<'a>(&self, fs: &'a FatFilesystemInner);
23
24    /// Takes an open count and opens the underlying node if not already open.
25    fn open_ref<'a>(&'a self, fs: &'a FatFilesystemInner) -> Result<(), Status>;
26
27    /// Releases an open count.
28    fn close_ref(&self, fs: &FatFilesystemInner);
29
30    /// Close the underlying node and all of its children, regardless of the number of open
31    /// connections.
32    fn shut_down(&self, fs: &FatFilesystemInner) -> Result<(), Status>;
33
34    /// Flushes the directory entry for this node.
35    fn flush_dir_entry(&self, fs: &FatFilesystemInner) -> Result<(), Status>;
36
37    /// Called when the node has been successfully deleted.
38    fn did_delete(&self);
39}
40
41#[derive(Clone, Debug)]
42/// This enum is used to represent values which could be either a FatDirectory
43/// or a FatFile. This holds a strong reference to the contained file/directory.
44pub enum FatNode {
45    Dir(Arc<FatDirectory>),
46    File(Arc<FatFile>),
47}
48
49impl FatNode {
50    /// Downgrade this FatNode into a WeakFatNode.
51    pub fn downgrade(&self) -> WeakFatNode {
52        match self {
53            FatNode::Dir(a) => WeakFatNode::Dir(Arc::downgrade(a)),
54            FatNode::File(b) => WeakFatNode::File(Arc::downgrade(b)),
55        }
56    }
57
58    pub fn as_node(&self) -> &(dyn Node + 'static) {
59        match self {
60            FatNode::Dir(ref a) => a.as_ref() as &dyn Node,
61            FatNode::File(ref b) => b.as_ref() as &dyn Node,
62        }
63    }
64}
65
66impl<'a> Deref for FatNode {
67    type Target = dyn Node;
68
69    fn deref(&self) -> &Self::Target {
70        self.as_node()
71    }
72}
73
74/// The same as FatNode, but using a weak reference.
75#[derive(Debug)]
76pub enum WeakFatNode {
77    Dir(Weak<FatDirectory>),
78    File(Weak<FatFile>),
79}
80
81impl WeakFatNode {
82    /// Try and upgrade this WeakFatNode to a FatNode. Returns None
83    /// if the referenced object has been destroyed.
84    pub fn upgrade(&self) -> Option<FatNode> {
85        match self {
86            WeakFatNode::Dir(a) => a.upgrade().map(|val| FatNode::Dir(val)),
87            WeakFatNode::File(b) => b.upgrade().map(|val| FatNode::File(val)),
88        }
89    }
90}
91
92/// RAII class that will close nodes when dropped.  This should be created whilst the filesystem
93/// lock is not held since when it drops, it takes the filesystem lock.  This class is useful
94/// for instances where temporary open counts are required.
95pub struct Closer<'a> {
96    filesystem: &'a FatFilesystem,
97    nodes: std::vec::Vec<FatNode>,
98}
99
100impl<'a> Closer<'a> {
101    pub fn new(filesystem: &'a FatFilesystem) -> Self {
102        Closer { filesystem, nodes: Vec::new() }
103    }
104
105    pub fn add(&mut self, node: FatNode) -> FatNode {
106        self.nodes.push(node.clone());
107        node
108    }
109}
110
111impl Drop for Closer<'_> {
112    fn drop(&mut self) {
113        let lock = self.filesystem.lock();
114        self.nodes.drain(..).for_each(|n: FatNode| n.close_ref(&lock));
115    }
116}
fuchsia_fatfs/node.rs

fuchsia_fatfs/
node.rs
