1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159

use crate::config::DCACHE_SIZE;
use crate::error::CNFSError::{InvalidPath, PathNotFound};
use crate::error::CNFSResult;
use crate::sync::UPCell;
use crate::vfs::mnt::MNTPOINT_TABLE;
use crate::vfs::path::Path;
use alloc::collections::BTreeMap;
use alloc::string::{String, ToString};
use alloc::sync::Arc;
use alloc::vec::Vec;
use core::cell::{Ref, RefMut};
use lazy_static::lazy_static;
use crate::vfs::vinode::{VInode, VInodeRef, VInodeType};

pub struct Dentry
{
    pub path: Path,
    pub inode: VInodeRef,
    pub exist: UPCell<bool>,
}

impl Dentry
{
    pub fn new(path: Path, inode: VInodeRef) -> Self
    {
        Dentry { path, inode, exist: unsafe { UPCell::new(true) } }
    }

    pub fn inode(&self) -> Ref<'_, VInode>
    {
        self.inode.0.shared_access()
    }

    pub fn inode_mut(&self) -> RefMut<'_, VInode>
    {
        self.inode.0.exclusive_access()
    }
}

lazy_static! {
    pub static ref DCACHE: UPCell<BTreeMap<String, Vec<Arc<Dentry>>>> = unsafe{UPCell::new(BTreeMap::new())};
}

pub(crate) fn insert_dcache(dentry: Arc<Dentry>)
{
    let mut dcache = DCACHE.exclusive_access();
    while dcache.len() >= DCACHE_SIZE
    {
        dcache.pop_first();
    }
    let vec = dcache
        .entry(dentry.path[dentry.path.len() - 1].clone()).or_insert(Vec::new());
    if vec.iter().find(|x| { x.path == dentry.path }).is_none()
    {
        vec.push(dentry);
    }
}

pub(crate) fn remove_dcache(path: &Path)
{
    let mut dcache = DCACHE.exclusive_access();
    let cached = dcache.get_mut(path[path.len() - 1].as_str());
    if let Some(vec) = cached
    {
        vec.retain(|d| { d.path != *path });
    }
}

/// Look up a dentry from the given path
pub(crate) fn lookup_dentry(path: &Path) -> CNFSResult<Arc<Dentry>>
{
    if path.len() == 0 { return Err(InvalidPath.into()); }
    // first we look up the cache
    let dcache = DCACHE.shared_access();

    let mut curr = path.clone();
    let mut cached = dcache.get(curr[curr.len() - 1].as_str());
    let mut cached_dentry: Option<Arc<Dentry>> = None;
    'outer: loop
    {
        if let Some(mnt) = MNTPOINT_TABLE.shared_access().get(&curr)
        {
            cached_dentry = Some(Arc::new(Dentry::new(curr,
                                                      VInodeRef::new(mnt.fs.root_inode()))));
            break 'outer;
        } else if let Some(cached_vec) = cached
        {
            for c in cached_vec.iter()
            {
                if c.path == curr
                {
                    cached_dentry = Some(c.clone());
                    break 'outer;
                }
            }
            cached = None;
        } else if let Some(p) = curr.parent() {
            curr = p;
            cached = dcache.get(curr[curr.len() - 1].as_str());
        } else { break; }
    }
    drop(dcache);
    let mut search_parent: Option<Arc<Dentry>> = None;
    if cached_dentry.is_some() { search_parent = cached_dentry; } else {
        for mnt in MNTPOINT_TABLE.shared_access().iter()
        {
            if path.starts_with(mnt.0)
            {
                search_parent = Some(Arc::new(Dentry::new(mnt.0.clone(),
                                                          VInodeRef::new(mnt.1.fs.root_inode()))));
                insert_dcache(search_parent.clone().unwrap());
                break;
            }
        }
    }

    if search_parent.is_none() { return Err(PathNotFound); }
    let mut curr = search_parent.unwrap();
    loop {
        if *path == curr.path
        {
            return if *curr.exist.shared_access() { Ok(curr) } else { Err(PathNotFound) }
        }
        let name = path[curr.path.len()].to_string();
        match curr.clone().inode().lookup(name.as_str())
        {
            Ok(inode) => {
                curr = Arc::new(Dentry::new(path[..curr.path.len() + 1].into(),
                                            VInodeRef::new(inode)));
                insert_dcache(curr.clone());
            }
            Err(_) => { return Err(PathNotFound); }
        }
    }
}

pub type DentryType = VInodeType;

/// Create a dentry
pub(crate) fn create_dentry(path: &Path, inode_type: DentryType) -> CNFSResult<Arc<Dentry>>
{
    if path.len() == 0 { return Err(InvalidPath); }
    let i = lookup_dentry(&path.parent().unwrap())?.inode()
        .create(path[path.len() - 1].as_str(), inode_type)?;
    let dentry = Arc::new(Dentry::new(path.clone(),
                                      VInodeRef::new(i)));
    insert_dcache(dentry.clone());
    Ok(dentry)
}

/// Remove a dentry
pub(crate) fn remove_dentry(path: &Path) -> CNFSResult
{
    let dentry = lookup_dentry(&path)?;
    *dentry.exist.exclusive_access() = false;
    let parent_dentry = lookup_dentry(&path.parent().unwrap())?;
    remove_dcache(&path);
    parent_dentry.clone().inode().remove(path[path.len() - 1].as_str())
}