rCore-Tutorial-v3/os/src/fs/inode.rs

use easy_fs::{
    EasyFileSystem,
    Inode,
};
use crate::drivers::BLOCK_DEVICE;
use alloc::sync::Arc;
use lazy_static::*;
use bitflags::*;
use alloc::vec::Vec;
use spin::Mutex;

pub struct OSInode {
    readable: bool,
    writable: bool,
    inner: Mutex<OSInodeInner>,
}

pub struct OSInodeInner {
    offset: usize,
    inode: Arc<Inode>,
}

impl OSInode {
    pub fn new(
        readable: bool,
        writable: bool,
        inode: Arc<Inode>,
    ) -> Self {
        Self {
            readable,
            writable,
            inner: Mutex::new(OSInodeInner {
                offset: 0,
                inode,
            }),
        }
    }
    pub fn read_all(&self) -> Vec<u8> {
        let mut inner = self.inner.lock();
        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))
    };
}

pub fn list_apps() {
    println!("/**** APPS ****");
    for app in ROOT_INODE.ls() {
        println!("{}", app);
    }
    println!("**************/")
}

bitflags! {
    pub struct OpenFlags: u32 {
        const RDONLY = 0;
        const WRONLY = 1 << 0;
        const RDWR = 1 << 1;
        const CREATE = 1 << 9;
        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)
        }
    }
}

pub fn open_file(name: &str, flags: OpenFlags) -> Option<Arc<OSInode>> {
    let (readable, writable) = flags.read_write();
    // TODO: do not support CREATE or TRUNC flags now
    ROOT_INODE.find(name)
        .map(|inode| {
            Arc::new(OSInode::new(
                readable,
                writable,
                inode
            ))
        })
}