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

//! `Arc<Inode>` -> `OSInodeInner`: In order to open files concurrently
//! we need to wrap `Inode` into `Arc`,but `Mutex` in `Inode` prevents
//! file systems from being accessed simultaneously
//!
//! `UPSafeCell<OSInodeInner>` -> `OSInode`: for static `ROOT_INODE`,we
//! need to wrap `OSInodeInner` into `UPSafeCell`
use super::File;
use crate::drivers::BLOCK_DEVICE;
use crate::mm::UserBuffer;
use crate::sync::UPSafeCell;
use alloc::sync::Arc;
use alloc::vec::Vec;
use bitflags::*;
use easy_fs::{EasyFileSystem, Inode};
use lazy_static::*;

/// inode in memory
/// A wrapper around a filesystem inode
/// to implement File trait atop
pub struct OSInode {
    readable: bool,
    writable: bool,
    inner: UPSafeCell<OSInodeInner>,
}
/// The OS inode inner in 'UPSafeCell'
pub struct OSInodeInner {
    offset: usize,
    inode: Arc<Inode>,
}

impl OSInode {
    /// create a new inode in memory
    pub fn new(readable: bool, writable: bool, inode: Arc<Inode>) -> Self {
        Self {
            readable,
            writable,
            inner: unsafe { UPSafeCell::new(OSInodeInner { offset: 0, inode }) },
        }
    }
    /// read all data from the inode
    pub fn read_all(&self) -> Vec<u8> {
        let mut inner = self.inner.exclusive_access();
        let mut buffer = [0u8; 512];
        let mut v: Vec<u8> = Vec::new();
        loop {
            let len = inner.inode.read_at(inner.offset, &mut buffer);
            if len == 0 {
                break;
            }
            inner.offset += len;
            v.extend_from_slice(&buffer[..len]);
        }
        v
    }
}

lazy_static! {
    pub static ref ROOT_INODE: Arc<Inode> = {
        let efs = EasyFileSystem::open(BLOCK_DEVICE.clone());
        Arc::new(EasyFileSystem::root_inode(&efs))
    };
}

/// List all apps in the root directory
pub fn list_apps() {
    println!("/**** APPS ****");
    for app in ROOT_INODE.ls() {
        println!("{}", app);
    }
    println!("**************/");
}

bitflags! {
    ///  The flags argument to the open() system call is constructed by ORing together zero or more of the following values:
    pub struct OpenFlags: u32 {
        /// readyonly
        const RDONLY = 0;
        /// writeonly
        const WRONLY = 1 << 0;
        /// read and write
        const RDWR = 1 << 1;
        /// create new file
        const CREATE = 1 << 9;
        /// truncate file size to 0
        const TRUNC = 1 << 10;
    }
}

impl OpenFlags {
    /// Do not check validity for simplicity
    /// Return (readable, writable)
    pub fn read_write(&self) -> (bool, bool) {
        if self.is_empty() {
            (true, false)
        } else if self.contains(Self::WRONLY) {
            (false, true)
        } else {
            (true, true)
        }
    }
}

/// Open a file
pub fn open_file(name: &str, flags: OpenFlags) -> Option<Arc<OSInode>> {
    let (readable, writable) = flags.read_write();
    if flags.contains(OpenFlags::CREATE) {
        if let Some(inode) = ROOT_INODE.find(name) {
            // clear size
            inode.clear();
            Some(Arc::new(OSInode::new(readable, writable, inode)))
        } else {
            // create file
            ROOT_INODE
                .create(name)
                .map(|inode| Arc::new(OSInode::new(readable, writable, inode)))
        }
    } else {
        ROOT_INODE.find(name).map(|inode| {
            if flags.contains(OpenFlags::TRUNC) {
                inode.clear();
            }
            Arc::new(OSInode::new(readable, writable, inode))
        })
    }
}

impl File for OSInode {
    fn readable(&self) -> bool {
        self.readable
    }
    fn writable(&self) -> bool {
        self.writable
    }
    fn read(&self, mut buf: UserBuffer) -> usize {
        let mut inner = self.inner.exclusive_access();
        let mut total_read_size = 0usize;
        for slice in buf.buffers.iter_mut() {
            let read_size = inner.inode.read_at(inner.offset, *slice);
            if read_size == 0 {
                break;
            }
            inner.offset += read_size;
            total_read_size += read_size;
        }
        total_read_size
    }
    fn write(&self, buf: UserBuffer) -> usize {
        let mut inner = self.inner.exclusive_access();
        let mut total_write_size = 0usize;
        for slice in buf.buffers.iter() {
            let write_size = inner.inode.write_at(inner.offset, *slice);
            assert_eq!(write_size, slice.len());
            inner.offset += write_size;
            total_write_size += write_size;
        }
        total_write_size
    }
}