#![allow(dead_code)] use core::{any::Any, fmt::Debug}; use alloc::{ collections::BTreeMap, string::String, sync::{Arc, Weak}, vec::Vec, }; use crate::{ filesystem::vfs::{ core::generate_inode_id, file::{FileMode, FilePrivateData}, FileSystem, FileType, IndexNode, InodeId, Metadata, PollStatus, }, include::bindings::bindings::{ EFAULT, EINVAL, EISDIR, ENOENT, ENOSPC, ENOTDIR, ENOTEMPTY, ENOTSUP, EPERM, EROFS, }, io::{device::LBA_SIZE, disk_info::Partition, SeekFrom}, kerror, libs::{ spinlock::{SpinLock, SpinLockGuard}, vec_cursor::VecCursor, }, time::TimeSpec, }; use super::{ bpb::{BiosParameterBlock, FATType}, entry::{FATDir, FATDirEntry, FATDirIter, FATEntry}, utils::RESERVED_CLUSTERS, }; /// FAT32文件系统的最大的文件大小 pub const MAX_FILE_SIZE: u64 = 0xffff_ffff; /// @brief 表示当前簇和上一个簇的关系的结构体 /// 定义这样一个结构体的原因是，FAT文件系统的文件中，前后两个簇具有关联关系。 #[derive(Debug, Clone, Copy, Default)] pub struct Cluster { pub cluster_num: u64, pub parent_cluster: u64, } impl PartialOrd for Cluster { /// @brief 根据当前簇号比较大小 fn partial_cmp(&self, other: &Self) -> Option { return self.cluster_num.partial_cmp(&other.cluster_num); } } impl PartialEq for Cluster { /// @brief 根据当前簇号比较是否相等 fn eq(&self, other: &Self) -> bool { self.cluster_num == other.cluster_num } } impl Eq for Cluster {} #[derive(Debug)] pub struct FATFileSystem { /// 当前文件系统所在的分区 pub partition: Arc, /// 当前文件系统的BOPB pub bpb: BiosParameterBlock, /// 当前文件系统的第一个数据扇区（相对分区开始位置） pub first_data_sector: u64, /// 文件系统信息结构体 pub fs_info: Arc, /// 文件系统的根inode root_inode: Arc, } /// FAT文件系统的Inode #[derive(Debug)] pub struct LockedFATInode(SpinLock); #[derive(Debug)] pub struct LockedFATFsInfo(SpinLock); impl LockedFATFsInfo { #[inline] pub fn new(fs_info: FATFsInfo) -> Self { return Self(SpinLock::new(fs_info)); } } #[derive(Debug)] pub struct FATInode { /// 指向父Inode的弱引用 parent: Weak, /// 指向自身的弱引用 self_ref: Weak, /// 子Inode的B树. 该数据结构用作缓存区。其中，它的key表示inode的名称。 /// 请注意，由于FAT的查询过程对大小写不敏感，因此我们选择让key全部是大写的，方便统一操作。 children: BTreeMap>, /// 当前inode的元数据 metadata: Metadata, /// 指向inode所在的文件系统对象的指针 fs: Weak, /// 根据不同的Inode类型，创建不同的私有字段 inode_type: FATDirEntry, } impl FATInode { /// @brief 更新当前inode的元数据 pub fn update_metadata(&mut self) { // todo: 更新文件的访问时间等信息 match &self.inode_type { FATDirEntry::File(f) | FATDirEntry::VolId(f) => { self.metadata.size = f.size() as i64; } FATDirEntry::Dir(d) => { self.metadata.size = d.size(&self.fs.upgrade().unwrap().clone()) as i64; } FATDirEntry::UnInit => { kerror!("update_metadata: Uninitialized FATDirEntry: {:?}", self); return; } }; } fn find(&mut self, name: &str) -> Result, i32> { match &self.inode_type { FATDirEntry::Dir(d) => { // 尝试在缓存区查找 if let Some(entry) = self.children.get(&name.to_uppercase()) { return Ok(entry.clone()); } // 在缓存区找不到 // 在磁盘查找 let fat_entry: FATDirEntry = d.find_entry(name, None, None, self.fs.upgrade().unwrap())?; // kdebug!("find entry from disk ok, entry={fat_entry:?}"); // 创建新的inode let entry_inode: Arc = LockedFATInode::new( self.fs.upgrade().unwrap(), self.self_ref.clone(), fat_entry, ); // 加入缓存区, 由于FAT文件系统的大小写不敏感问题，因此存入缓存区的key应当是全大写的 self.children .insert(name.to_uppercase(), entry_inode.clone()); return Ok(entry_inode); } FATDirEntry::UnInit => { panic!( "Uninitialized FAT Inode, fs = {:?}, inode={self:?}", self.fs ) } _ => { return Err(-(ENOTDIR as i32)); } } } } impl LockedFATInode { pub fn new( fs: Arc, parent: Weak, inode_type: FATDirEntry, ) -> Arc { let file_type = if let FATDirEntry::Dir(_) = inode_type { FileType::Dir } else { FileType::File }; let inode: Arc = Arc::new(LockedFATInode(SpinLock::new(FATInode { parent: parent, self_ref: Weak::default(), children: BTreeMap::new(), fs: Arc::downgrade(&fs), inode_type: inode_type, metadata: Metadata { dev_id: 0, inode_id: generate_inode_id(), size: 0, blk_size: fs.bpb.bytes_per_sector as usize, blocks: if let FATType::FAT32(_) = fs.bpb.fat_type { fs.bpb.total_sectors_32 as usize } else { fs.bpb.total_sectors_16 as usize }, atime: TimeSpec::default(), mtime: TimeSpec::default(), ctime: TimeSpec::default(), file_type: file_type, mode: 0o777, nlinks: 1, uid: 0, gid: 0, raw_dev: 0, }, }))); inode.0.lock().self_ref = Arc::downgrade(&inode); inode.0.lock().update_metadata(); return inode; } } /// FsInfo结构体（内存中的一份拷贝，当卸载卷或者sync的时候，把它写入磁盘） #[derive(Debug)] pub struct FATFsInfo { /// Lead Signature - must equal 0x41615252 lead_sig: u32, /// Value must equal 0x61417272 struc_sig: u32, /// 空闲簇数目 free_count: u32, /// 第一个空闲簇的位置（不一定准确，仅供加速查找） next_free: u32, /// 0xAA550000 trail_sig: u32, /// Dirty flag to flush to disk dirty: bool, /// FsInfo Structure 在磁盘上的字节偏移量 /// Not present for FAT12 and FAT16 offset: Option, } impl FileSystem for FATFileSystem { fn root_inode(&self) -> Arc { return self.root_inode.clone(); } fn info(&self) -> crate::filesystem::vfs::FsInfo { todo!() } /// @brief 本函数用于实现动态转换。 /// 具体的文件系统在实现本函数时，最简单的方式就是：直接返回self fn as_any_ref(&self) -> &dyn Any { self } } impl FATFileSystem { pub fn new(partition: Arc) -> Result, i32> { let bpb = BiosParameterBlock::new(partition.clone())?; // 从磁盘上读取FAT32文件系统的FsInfo结构体 let fs_info: FATFsInfo = match bpb.fat_type { FATType::FAT32(bpb32) => { let fs_info_in_disk_bytes_offset = partition.lba_start * LBA_SIZE as u64 + bpb32.fs_info as u64 * bpb.bytes_per_sector as u64; FATFsInfo::new( partition.clone(), fs_info_in_disk_bytes_offset, bpb.bytes_per_sector as usize, )? } _ => FATFsInfo::default(), }; // 根目录项占用的扇区数（向上取整） let root_dir_sectors: u64 = ((bpb.root_entries_cnt as u64 * 32) + (bpb.bytes_per_sector as u64 - 1)) / (bpb.bytes_per_sector as u64); // FAT表大小（单位：扇区） let fat_size = if bpb.fat_size_16 != 0 { bpb.fat_size_16 as u64 } else { match bpb.fat_type { FATType::FAT32(x) => x.fat_size_32 as u64, _ => { kerror!("FAT12 and FAT16 volumes should have non-zero BPB_FATSz16"); return Err(-(EINVAL as i32)); } } }; let first_data_sector = bpb.rsvd_sec_cnt as u64 + (bpb.num_fats as u64 * fat_size) + root_dir_sectors; // 创建文件系统的根节点 let root_inode: Arc = Arc::new(LockedFATInode(SpinLock::new(FATInode { parent: Weak::default(), self_ref: Weak::default(), children: BTreeMap::new(), fs: Weak::default(), inode_type: FATDirEntry::UnInit, metadata: Metadata { dev_id: 0, inode_id: generate_inode_id(), size: 0, blk_size: bpb.bytes_per_sector as usize, blocks: if let FATType::FAT32(_) = bpb.fat_type { bpb.total_sectors_32 as usize } else { bpb.total_sectors_16 as usize }, atime: TimeSpec::default(), mtime: TimeSpec::default(), ctime: TimeSpec::default(), file_type: FileType::Dir, mode: 0o777, nlinks: 1, uid: 0, gid: 0, raw_dev: 0, }, }))); let result: Arc = Arc::new(FATFileSystem { partition: partition, bpb, first_data_sector, fs_info: Arc::new(LockedFATFsInfo::new(fs_info)), root_inode: root_inode, }); // 对root inode加锁，并继续完成初始化工作 let mut root_guard: SpinLockGuard = result.root_inode.0.lock(); root_guard.inode_type = FATDirEntry::Dir(result.root_dir()); root_guard.parent = Arc::downgrade(&result.root_inode); root_guard.self_ref = Arc::downgrade(&result.root_inode); root_guard.fs = Arc::downgrade(&result); // 释放锁 drop(root_guard); return Ok(result); } /// @brief 计算每个簇有多少个字节 #[inline] pub fn bytes_per_cluster(&self) -> u64 { return (self.bpb.bytes_per_sector as u64) * (self.bpb.sector_per_cluster as u64); } /// @brief 读取当前簇在FAT表中存储的信息 /// /// @param cluster 当前簇 /// /// @return Ok(FATEntry) 当前簇在FAT表中，存储的信息。（详情见FATEntry的注释） /// @return Err(i32) 错误码 pub fn get_fat_entry(&self, cluster: Cluster) -> Result { let current_cluster = cluster.cluster_num; let fat_type: FATType = self.bpb.fat_type; // 获取FAT表的起始扇区（相对分区起始扇区的偏移量） let fat_start_sector = self.fat_start_sector(); let bytes_per_sec = self.bpb.bytes_per_sector as u64; // cluster对应的FAT表项在分区内的字节偏移量 let fat_bytes_offset = fat_type.get_fat_bytes_offset(cluster, fat_start_sector, bytes_per_sec); // FAT表项所在的LBA地址 // let fat_ent_lba = self.get_lba_from_offset(self.bytes_to_sector(fat_bytes_offset)); let fat_ent_lba = self.partition.lba_start + fat_bytes_offset / LBA_SIZE as u64; // FAT表项在逻辑块内的字节偏移量 let blk_offset = self.get_in_block_offset(fat_bytes_offset); let mut v = Vec::::new(); v.resize(self.bpb.bytes_per_sector as usize, 0); self.partition .disk() .read_at(fat_ent_lba as usize, 1 * self.lba_per_sector(), &mut v)?; let mut cursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(blk_offset as i64))?; let res: FATEntry = match self.bpb.fat_type { FATType::FAT12(_) => { let mut entry = cursor.read_u16()?; // 由于FAT12文件系统的FAT表，每个entry占用1.5字节，因此奇数的簇需要取高12位的值。 if (current_cluster & 1) > 0 { entry >>= 4; } else { entry &= 0x0fff; } if entry == 0 { FATEntry::Unused } else if entry == 0x0ff7 { FATEntry::Bad } else if entry >= 0x0ff8 { FATEntry::EndOfChain } else { FATEntry::Next(Cluster { cluster_num: entry as u64, parent_cluster: current_cluster, }) } } FATType::FAT16(_) => { let entry = cursor.read_u16()?; if entry == 0 { FATEntry::Unused } else if entry == 0xfff7 { FATEntry::Bad } else if entry >= 0xfff8 { FATEntry::EndOfChain } else { FATEntry::Next(Cluster { cluster_num: entry as u64, parent_cluster: current_cluster, }) } } FATType::FAT32(_) => { let entry = cursor.read_u32()? & 0x0fffffff; match entry { _n if (current_cluster >= 0x0ffffff7 && current_cluster <= 0x0fffffff) => { // 当前簇号不是一个能被获得的簇（可能是文件系统出错了） kerror!("FAT32 get fat entry: current cluster number [{}] is not an allocatable cluster number.", current_cluster); FATEntry::Bad } 0 => FATEntry::Unused, 0x0ffffff7 => FATEntry::Bad, 0x0ffffff8..=0x0fffffff => FATEntry::EndOfChain, _n => FATEntry::Next(Cluster { cluster_num: entry as u64, parent_cluster: current_cluster, }), } } }; return Ok(res); } /// @brief 读取当前簇在FAT表中存储的信息（直接返回读取到的值，而不加处理） /// /// @param cluster 当前簇 /// /// @return Ok(u64) 当前簇在FAT表中，存储的信息。 /// @return Err(i32) 错误码 pub fn get_fat_entry_raw(&self, cluster: Cluster) -> Result { let current_cluster = cluster.cluster_num; let fat_type: FATType = self.bpb.fat_type; // 获取FAT表的起始扇区（相对分区起始扇区的偏移量） let fat_start_sector = self.fat_start_sector(); let bytes_per_sec = self.bpb.bytes_per_sector as u64; // cluster对应的FAT表项在分区内的字节偏移量 let fat_bytes_offset = fat_type.get_fat_bytes_offset(cluster, fat_start_sector, bytes_per_sec); // FAT表项所在的LBA地址 let fat_ent_lba = self.get_lba_from_offset(self.bytes_to_sector(fat_bytes_offset)); // FAT表项在逻辑块内的字节偏移量 let blk_offset = self.get_in_block_offset(fat_bytes_offset); let mut v = Vec::::new(); v.resize(self.bpb.bytes_per_sector as usize, 0); self.partition .disk() .read_at(fat_ent_lba, 1 * self.lba_per_sector(), &mut v)?; let mut cursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(blk_offset as i64))?; let res = match self.bpb.fat_type { FATType::FAT12(_) => { let mut entry = cursor.read_u16()?; entry = if (current_cluster & 0x0001) > 0 { entry >> 4 } else { entry & 0x0fff }; entry as u64 } FATType::FAT16(_) => { let entry = (cursor.read_u16()?) as u64; entry } FATType::FAT32(_) => { let entry = cursor.read_u32()? & 0x0fff_ffff; entry as u64 } }; return Ok(res); } /// @brief 获取当前文件系统的root inode，在磁盘上的字节偏移量 pub fn root_dir_bytes_offset(&self) -> u64 { match self.bpb.fat_type { FATType::FAT32(s) => { let first_sec_cluster: u64 = (s.root_cluster as u64 - 2) * (self.bpb.sector_per_cluster as u64) + self.first_data_sector; return (self.get_lba_from_offset(first_sec_cluster) * LBA_SIZE) as u64; } _ => { let root_sec = (self.bpb.rsvd_sec_cnt as u64) + (self.bpb.num_fats as u64) * (self.bpb.fat_size_16 as u64); return (self.get_lba_from_offset(root_sec) * LBA_SIZE) as u64; } } } /// @brief 获取当前文件系统的根目录项区域的结束位置，在磁盘上的字节偏移量。 /// 请注意，当前函数只对FAT12/FAT16生效。对于FAT32,返回None pub fn root_dir_end_bytes_offset(&self) -> Option { match self.bpb.fat_type { FATType::FAT12(_) | FATType::FAT16(_) => { return Some( self.root_dir_bytes_offset() + (self.bpb.root_entries_cnt as u64) * 32, ); } _ => { return None; } } } /// @brief 获取簇在磁盘内的字节偏移量(相对磁盘起始位置。注意，不是分区内偏移量) pub fn cluster_bytes_offset(&self, cluster: Cluster) -> u64 { if cluster.cluster_num >= 2 { // 指定簇的第一个扇区号 let first_sec_of_cluster = (cluster.cluster_num - 2) * (self.bpb.sector_per_cluster as u64) + self.first_data_sector; return (self.get_lba_from_offset(first_sec_of_cluster) * LBA_SIZE) as u64; } else { return 0; } } /// @brief 获取一个空闲簇 /// /// @param prev_cluster 簇链的前一个簇。本函数将会把新获取的簇，连接到它的后面。 /// /// @return Ok(Cluster) 新获取的空闲簇 /// @return Err(i32) 错误码 pub fn allocate_cluster(&self, prev_cluster: Option) -> Result { let end_cluster: Cluster = self.max_cluster_number(); let start_cluster: Cluster = match self.bpb.fat_type { FATType::FAT32(_) => { let next_free: u64 = match self.fs_info.0.lock().next_free() { Some(x) => x, None => 0xffffffff, }; if next_free < end_cluster.cluster_num { Cluster::new(next_free) } else { Cluster::new(RESERVED_CLUSTERS as u64) } } _ => Cluster::new(RESERVED_CLUSTERS as u64), }; // 寻找一个空的簇 let free_cluster: Cluster = match self.get_free_cluster(start_cluster, end_cluster) { Ok(c) => c, Err(_) if start_cluster.cluster_num > RESERVED_CLUSTERS as u64 => { self.get_free_cluster(Cluster::new(RESERVED_CLUSTERS as u64), end_cluster)? } Err(e) => return Err(e), }; self.set_entry(free_cluster, FATEntry::EndOfChain)?; // 减少空闲簇计数 self.fs_info.0.lock().update_free_count_delta(-1); // 更新搜索空闲簇的参考量 self.fs_info .0 .lock() .update_next_free((free_cluster.cluster_num + 1) as u32); // 如果这个空闲簇不是簇链的第一个簇，那么把当前簇跟前一个簇连上。 if let Some(prev_cluster) = prev_cluster { // kdebug!("set entry, prev ={prev_cluster:?}, next = {free_cluster:?}"); self.set_entry(prev_cluster, FATEntry::Next(free_cluster))?; } // 清空新获取的这个簇 self.zero_cluster(free_cluster)?; return Ok(free_cluster); } /// @brief 释放簇链上的所有簇 /// /// @param start_cluster 簇链的第一个簇 pub fn deallocate_cluster_chain(&self, start_cluster: Cluster) -> Result<(), i32> { let clusters: Vec = self.clusters(start_cluster); for c in clusters { self.deallocate_cluster(c)?; } return Ok(()); } /// @brief 释放簇 /// /// @param 要释放的簇 pub fn deallocate_cluster(&self, cluster: Cluster) -> Result<(), i32> { let entry: FATEntry = self.get_fat_entry(cluster)?; // 如果不是坏簇 if entry != FATEntry::Bad { self.set_entry(cluster, FATEntry::Unused)?; self.fs_info.0.lock().update_free_count_delta(1); // 安全选项：清空被释放的簇 #[cfg(feature = "secure")] self.zero_cluster(cluster)?; return Ok(()); } else { // 不能释放坏簇 kerror!("Bad clusters cannot be freed."); return Err(-(EFAULT as i32)); } } /// @brief 获取文件系统的根目录项 pub fn root_dir(&self) -> FATDir { match self.bpb.fat_type { FATType::FAT32(s) => { return FATDir { first_cluster: Cluster::new(s.root_cluster as u64), dir_name: String::from("/"), root_offset: None, short_dir_entry: None, loc: None, }; } _ => FATDir { first_cluster: Cluster::new(0), dir_name: String::from("/"), root_offset: Some(self.root_dir_bytes_offset()), short_dir_entry: None, loc: None, }, } } /// @brief 获取FAT表的起始扇区（相对分区起始扇区的偏移量） pub fn fat_start_sector(&self) -> u64 { let active_fat = self.active_fat(); let fat_size = self.fat_size(); return self.bpb.rsvd_sec_cnt as u64 + active_fat * fat_size; } /// @brief 获取当前活动的FAT表 pub fn active_fat(&self) -> u64 { if self.mirroring_enabled() { return 0; } else { match self.bpb.fat_type { FATType::FAT32(bpb32) => { return (bpb32.ext_flags & 0x0f) as u64; } _ => { return 0; } } } } /// @brief 获取当前文件系统的每个FAT表的大小 pub fn fat_size(&self) -> u64 { if self.bpb.fat_size_16 != 0 { return self.bpb.fat_size_16 as u64; } else { match self.bpb.fat_type { FATType::FAT32(bpb32) => { return bpb32.fat_size_32 as u64; } _ => { panic!("FAT12 and FAT16 volumes should have non-zero BPB_FATSz16"); } } } } /// @brief 判断当前文件系统是否启用了FAT表镜像 pub fn mirroring_enabled(&self) -> bool { match self.bpb.fat_type { FATType::FAT32(bpb32) => { return (bpb32.ext_flags & 0x80) == 0; } _ => { return false; } } } /// @brief 根据分区内的扇区偏移量，获得在磁盘上的LBA地址 #[inline] pub fn get_lba_from_offset(&self, in_partition_sec_offset: u64) -> usize { return (self.partition.lba_start + in_partition_sec_offset * (self.bpb.bytes_per_sector as u64 / LBA_SIZE as u64)) as usize; } /// @brief 获取每个扇区占用多少个LBA #[inline] pub fn lba_per_sector(&self) -> usize { return self.bpb.bytes_per_sector as usize / LBA_SIZE; } /// @brief 将分区内字节偏移量转换为扇区偏移量 #[inline] pub fn bytes_to_sector(&self, in_partition_bytes_offset: u64) -> u64 { return in_partition_bytes_offset / (self.bpb.bytes_per_sector as u64); } /// @brief 根据磁盘上的字节偏移量，获取对应位置在分区内的字节偏移量 #[inline] pub fn get_in_partition_bytes_offset(&self, disk_bytes_offset: u64) -> u64 { return disk_bytes_offset - (self.partition.lba_start * LBA_SIZE as u64); } /// @brief 根据字节偏移量计算在逻辑块内的字节偏移量 #[inline] pub fn get_in_block_offset(&self, bytes_offset: u64) -> u64 { return bytes_offset % LBA_SIZE as u64; } /// @brief 获取在FAT表中，以start_cluster开头的FAT链的所有簇的信息 /// /// @param start_cluster 整个FAT链的起始簇号 pub fn clusters(&self, start_cluster: Cluster) -> Vec { return self.cluster_iter(start_cluster).collect(); } /// @brief 获取在FAT表中，以start_cluster开头的FAT链的长度（总计经过多少个簇） /// /// @param start_cluster 整个FAT链的起始簇号 pub fn num_clusters_chain(&self, start_cluster: Cluster) -> u64 { return self .cluster_iter(start_cluster) .fold(0, |size, _cluster| size + 1); } /// @brief 获取一个簇迭代器对象 /// /// @param start_cluster 整个FAT链的起始簇号 fn cluster_iter(&self, start_cluster: Cluster) -> ClusterIter { return ClusterIter { current_cluster: Some(start_cluster), fs: self, }; } /// @brief 获取从start_cluster开始的簇链中，第n个簇的信息。（请注意，下标从0开始） #[inline] pub fn get_cluster_by_relative(&self, start_cluster: Cluster, n: usize) -> Option { return self.cluster_iter(start_cluster).skip(n).next(); } /// @brief 获取整个簇链的最后一个簇 #[inline] pub fn get_last_cluster(&self, start_cluster: Cluster) -> Option { return self.cluster_iter(start_cluster).last(); } /// @brief 判断FAT文件系统的shut bit是否正常。 /// shut bit 表示文件系统是否正常卸载。如果这一位是1,则表示这个卷是“干净的” /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html /// /// @return Ok(true) 正常 /// @return Ok(false) 不正常 /// @return Err(i32) 在判断时发生错误 pub fn is_shut_bit_ok(&mut self) -> Result { match self.bpb.fat_type { FATType::FAT32(_) => { // 对于FAT32, error bit位于第一个扇区的第8字节。 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0800_0000; return Ok(bit > 0); } FATType::FAT16(_) => { let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x8000; return Ok(bit > 0); } _ => return Ok(true), } } /// @brief 判断FAT文件系统的hard error bit是否正常。 /// 如果此位为0，则文件系统驱动程序在上次安装卷时遇到磁盘 I/O 错误，这表明 /// 卷上的某些扇区可能已损坏。 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html /// /// @return Ok(true) 正常 /// @return Ok(false) 不正常 /// @return Err(i32) 在判断时发生错误 pub fn is_hard_error_bit_ok(&mut self) -> Result { match self.bpb.fat_type { FATType::FAT32(_) => { let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0400_0000; return Ok(bit > 0); } FATType::FAT16(_) => { let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x4000; return Ok(bit > 0); } _ => return Ok(true), } } /// @brief 设置文件系统的shut bit为正常状态 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html /// /// @return Ok(()) 设置成功 /// @return Err(i32) 在设置过程中，出现错误 pub fn set_shut_bit_ok(&mut self) -> Result<(), i32> { match self.bpb.fat_type { FATType::FAT32(_) => { let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0800_0000; self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; return Ok(()); } FATType::FAT16(_) => { let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x8000; self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; return Ok(()); } _ => return Ok(()), } } /// @brief 设置文件系统的hard error bit为正常状态 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html /// /// @return Ok(()) 设置成功 /// @return Err(i32) 在设置过程中，出现错误 pub fn set_hard_error_bit_ok(&mut self) -> Result<(), i32> { match self.bpb.fat_type { FATType::FAT32(_) => { let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0400_0000; self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; return Ok(()); } FATType::FAT16(_) => { let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x4000; self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; return Ok(()); } _ => return Ok(()), } } /// @brief 执行文件系统卸载前的一些准备工作：设置好对应的标志位，并把缓存中的数据刷入磁盘 pub fn umount(&mut self) -> Result<(), i32> { self.fs_info.0.lock().flush(&self.partition)?; self.set_shut_bit_ok()?; self.set_hard_error_bit_ok()?; self.partition.disk().sync()?; return Ok(()); } /// @brief 获取文件系统的最大簇号 pub fn max_cluster_number(&self) -> Cluster { match self.bpb.fat_type { FATType::FAT32(s) => { // FAT32 // 数据扇区数量（总扇区数-保留扇区-FAT占用的扇区） let data_sec: u64 = self.bpb.total_sectors_32 as u64 - (self.bpb.rsvd_sec_cnt as u64 + self.bpb.num_fats as u64 * s.fat_size_32 as u64); // 数据区的簇数量 let total_clusters: u64 = data_sec / self.bpb.sector_per_cluster as u64; // 返回最大的簇号 return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); } _ => { // FAT12 / FAT16 let root_dir_sectors: u64 = (((self.bpb.root_entries_cnt as u64) * 32) + self.bpb.bytes_per_sector as u64 - 1) / self.bpb.bytes_per_sector as u64; // 数据区扇区数 let data_sec: u64 = self.bpb.total_sectors_16 as u64 - (self.bpb.rsvd_sec_cnt as u64 + (self.bpb.num_fats as u64 * self.bpb.fat_size_16 as u64) + root_dir_sectors); let total_clusters = data_sec / self.bpb.sector_per_cluster as u64; return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); } } } /// @brief 在文件系统中寻找一个簇号在给定的范围（左闭右开区间）内的空闲簇 /// /// @param start_cluster 起始簇号 /// @param end_cluster 终止簇号（不包含） /// /// @return Ok(Cluster) 寻找到的空闲簇 /// @return Err(i32) 错误码。如果磁盘无剩余空间，或者簇号达到给定的最大值，则返回-ENOSPC. pub fn get_free_cluster( &self, start_cluster: Cluster, end_cluster: Cluster, ) -> Result { let max_cluster: Cluster = self.max_cluster_number(); let mut cluster: u64 = start_cluster.cluster_num; let fat_type: FATType = self.bpb.fat_type; let fat_start_sector: u64 = self.fat_start_sector(); let bytes_per_sec: u64 = self.bpb.bytes_per_sector as u64; match fat_type { FATType::FAT12(_) => { let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset(start_cluster, fat_start_sector, bytes_per_sec); let in_block_offset = self.get_in_block_offset(part_bytes_offset); let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); // 由于FAT12的FAT表不大于6K，因此直接读取6K let num_lba = (6 * 1024) / LBA_SIZE; let mut v: Vec = Vec::new(); v.resize(num_lba * LBA_SIZE, 0); self.partition.disk().read_at(lba, num_lba, &mut v)?; let mut cursor: VecCursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; let mut packed_val: u16 = cursor.read_u16()?; loop { let val = if (cluster & 0x1) > 0 { packed_val >> 4 } else { packed_val & 0x0fff }; if val == 0 { return Ok(Cluster::new(cluster as u64)); } cluster += 1; // 磁盘无剩余空间，或者簇号达到给定的最大值 if cluster == end_cluster.cluster_num || cluster == max_cluster.cluster_num { return Err(-(ENOSPC as i32)); } packed_val = match cluster & 1 { 0 => cursor.read_u16()?, _ => { let next_byte = cursor.read_u8()? as u16; (packed_val >> 8) | (next_byte << 8) } }; } } FATType::FAT16(_) => { // todo: 优化这里，减少读取磁盘的次数。 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( Cluster::new(cluster), fat_start_sector, bytes_per_sec, ); let in_block_offset = self.get_in_block_offset(part_bytes_offset); let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); let mut v: Vec = Vec::new(); v.resize(self.lba_per_sector() * LBA_SIZE, 0); self.partition .disk() .read_at(lba, self.lba_per_sector(), &mut v)?; let mut cursor: VecCursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; let val = cursor.read_u16()?; // 找到空闲簇 if val == 0 { return Ok(Cluster::new(val as u64)); } cluster += 1; } // 磁盘无剩余空间，或者簇号达到给定的最大值 return Err(-(ENOSPC as i32)); } FATType::FAT32(_) => { // todo: 优化这里，减少读取磁盘的次数。 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( Cluster::new(cluster), fat_start_sector, bytes_per_sec, ); let in_block_offset = self.get_in_block_offset(part_bytes_offset); let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); let mut v: Vec = Vec::new(); v.resize(self.lba_per_sector() * LBA_SIZE, 0); self.partition .disk() .read_at(lba, self.lba_per_sector(), &mut v)?; let mut cursor: VecCursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; let val = cursor.read_u32()? & 0x0fffffff; if val == 0 { return Ok(Cluster::new(cluster)); } cluster += 1; } // 磁盘无剩余空间，或者簇号达到给定的最大值 return Err(-(ENOSPC as i32)); } } } /// @brief 在FAT表中，设置指定的簇的信息。 /// /// @param cluster 目标簇 /// @param fat_entry 这个簇在FAT表中，存储的信息（下一个簇的簇号） pub fn set_entry(&self, cluster: Cluster, fat_entry: FATEntry) -> Result<(), i32> { // fat表项在分区上的字节偏移量 let fat_part_bytes_offset: u64 = self.bpb.fat_type.get_fat_bytes_offset( cluster, self.fat_start_sector(), self.bpb.bytes_per_sector as u64, ); match self.bpb.fat_type { FATType::FAT12(_) => { // 计算要写入的值 let raw_val: u16 = match fat_entry { FATEntry::Unused => 0, FATEntry::Bad => 0xff7, FATEntry::EndOfChain => 0xfff, FATEntry::Next(c) => c.cluster_num as u16, }; let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); let mut v: Vec = Vec::new(); v.resize(LBA_SIZE, 0); self.partition.disk().read_at(lba, 1, &mut v)?; let mut cursor: VecCursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; let old_val: u16 = cursor.read_u16()?; let new_val: u16 = if (cluster.cluster_num & 0x1) > 0 { (old_val & 0x000f) | (raw_val << 4) } else { (old_val & 0xf000) | raw_val }; // 写回数据到磁盘上 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; cursor.write_u16(new_val)?; self.partition.disk().write_at(lba, 1, cursor.as_slice())?; return Ok(()); } FATType::FAT16(_) => { // 计算要写入的值 let raw_val: u16 = match fat_entry { FATEntry::Unused => 0, FATEntry::Bad => 0xfff7, FATEntry::EndOfChain => 0xfdff, FATEntry::Next(c) => c.cluster_num as u16, }; let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); let mut v: Vec = Vec::new(); v.resize(LBA_SIZE, 0); self.partition.disk().read_at(lba, 1, &mut v)?; let mut cursor: VecCursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; cursor.write_u16(raw_val)?; self.partition.disk().write_at(lba, 1, cursor.as_slice())?; return Ok(()); } FATType::FAT32(_) => { let fat_size: u64 = self.fat_size(); let bound: u64 = if self.mirroring_enabled() { 1 } else { self.bpb.num_fats as u64 }; // kdebug!("set entry, bound={bound}, fat_size={fat_size}"); for i in 0..bound { // 当前操作的FAT表在磁盘上的字节偏移量 let f_offset: u64 = fat_part_bytes_offset + i * fat_size; let in_block_offset: u64 = self.get_in_block_offset(f_offset); let lba = self.get_lba_from_offset(self.bytes_to_sector(f_offset)); // kdebug!("set entry, lba={lba}, in_block_offset={in_block_offset}"); let mut v: Vec = Vec::new(); v.resize(LBA_SIZE, 0); self.partition.disk().read_at(lba, 1, &mut v)?; let mut cursor: VecCursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; // FAT32的高4位保留 let old_bits = cursor.read_u32()? & 0xf0000000; if fat_entry == FATEntry::Unused && cluster.cluster_num >= 0x0ffffff7 && cluster.cluster_num <= 0x0fffffff { kerror!( "FAT32: Reserved Cluster {:?} cannot be marked as free", cluster ); return Err(-(EPERM as i32)); } // 计算要写入的值 let mut raw_val: u32 = match fat_entry { FATEntry::Unused => 0, FATEntry::Bad => 0x0FFFFFF7, FATEntry::EndOfChain => 0x0FFFFFFF, FATEntry::Next(c) => c.cluster_num as u32, }; // 恢复保留位 raw_val |= old_bits; // kdebug!("sent entry, raw_val={raw_val}"); cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; cursor.write_u32(raw_val)?; self.partition.disk().write_at(lba, 1, cursor.as_slice())?; } return Ok(()); } } } /// @brief 清空指定的簇 /// /// @param cluster 要被清空的簇 pub fn zero_cluster(&self, cluster: Cluster) -> Result<(), i32> { // 准备数据，用于写入 let zeros: Vec = vec![0u8; self.bytes_per_cluster() as usize]; let offset: usize = self.cluster_bytes_offset(cluster) as usize; self.partition .disk() .device() .write_at(offset, zeros.len(), zeros.as_slice())?; return Ok(()); } } impl Drop for FATFileSystem { fn drop(&mut self) { let r = self.umount(); if r.is_err() { kerror!( "Umount FAT filesystem failed: errno={}, FS detail:{self:?}", r.unwrap_err() ); } } } impl FATFsInfo { const LEAD_SIG: u32 = 0x41615252; const STRUC_SIG: u32 = 0x61417272; const TRAIL_SIG: u32 = 0xAA550000; const FS_INFO_SIZE: u64 = 512; /// @brief 从磁盘上读取FAT文件系统的FSInfo结构体 /// /// @param partition 磁盘分区 /// @param in_disk_fs_info_offset FSInfo扇区在磁盘内的字节偏移量（单位：字节） /// @param bytes_per_sec 每扇区字节数 pub fn new( partition: Arc, in_disk_fs_info_offset: u64, bytes_per_sec: usize, ) -> Result { let mut v = Vec::::new(); v.resize(bytes_per_sec, 0); // 计算fs_info扇区在磁盘上的字节偏移量，从磁盘读取数据 partition .disk() .read_at(in_disk_fs_info_offset as usize / LBA_SIZE, 1, &mut v)?; let mut cursor = VecCursor::new(v); let mut fsinfo = FATFsInfo::default(); fsinfo.lead_sig = cursor.read_u32()?; cursor.seek(SeekFrom::SeekCurrent(480))?; fsinfo.struc_sig = cursor.read_u32()?; fsinfo.free_count = cursor.read_u32()?; fsinfo.next_free = cursor.read_u32()?; cursor.seek(SeekFrom::SeekCurrent(12))?; fsinfo.trail_sig = cursor.read_u32()?; fsinfo.dirty = false; fsinfo.offset = Some(in_disk_fs_info_offset); if fsinfo.is_valid() { return Ok(fsinfo); } else { kerror!("Error occurred while parsing FATFsInfo."); return Err(-(EINVAL as i32)); } } /// @brief 判断是否为正确的FsInfo结构体 fn is_valid(&self) -> bool { self.lead_sig == Self::LEAD_SIG && self.struc_sig == Self::STRUC_SIG && self.trail_sig == Self::TRAIL_SIG } /// @brief 根据fsinfo的信息，计算当前总的空闲簇数量 /// /// @param 当前文件系统的最大簇号 pub fn count_free_cluster(&self, max_cluster: Cluster) -> Option { let count_clusters = max_cluster.cluster_num - RESERVED_CLUSTERS as u64 + 1; // 信息不合理，当前的FsInfo中存储的free count大于计算出来的值 if self.free_count as u64 > count_clusters { return None; } else { match self.free_count { // free count字段不可用 0xffffffff => return None, // 返回FsInfo中存储的数据 n => return Some(n as u64), } } } /// @brief 更新FsInfo中的“空闲簇统计信息“为new_count /// /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 pub fn update_free_count_abs(&mut self, new_count: u32) { self.free_count = new_count; } /// @brief 更新FsInfo中的“空闲簇统计信息“，把它加上delta. /// /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 pub fn update_free_count_delta(&mut self, delta: i32) { self.free_count = (self.free_count as i32 + delta) as u32; } /// @brief 更新FsInfo中的“第一个空闲簇统计信息“为next_free. /// /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 pub fn update_next_free(&mut self, next_free: u32) { // 这个值是参考量，不一定要准确，仅供加速查找 self.next_free = next_free; } /// @brief 获取fs info 记载的第一个空闲簇。（不一定准确，仅供参考） pub fn next_free(&self) -> Option { match self.next_free { 0xffffffff => return None, 0 | 1 => return None, n => return Some(n as u64), }; } /// @brief 把fs info刷入磁盘 /// /// @param partition fs info所在的分区 pub fn flush(&self, partition: &Arc) -> Result<(), i32> { if let Some(off) = self.offset { let in_block_offset = off % LBA_SIZE as u64; let lba = off as usize / LBA_SIZE; let mut v: Vec = Vec::new(); v.resize(LBA_SIZE, 0); partition.disk().read_at(lba, 1, &mut v)?; let mut cursor: VecCursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; cursor.write_u32(self.lead_sig)?; cursor.seek(SeekFrom::SeekCurrent(480))?; cursor.write_u32(self.struc_sig)?; cursor.write_u32(self.free_count)?; cursor.write_u32(self.next_free)?; cursor.seek(SeekFrom::SeekCurrent(12))?; cursor.write_u32(self.trail_sig)?; partition.disk().write_at(lba, 1, cursor.as_slice())?; } return Ok(()); } /// @brief 读取磁盘上的Fs Info扇区，将里面的内容更新到结构体中 /// /// @param partition fs info所在的分区 pub fn update(&mut self, partition: Arc) -> Result<(), i32> { if let Some(off) = self.offset { let in_block_offset = off % LBA_SIZE as u64; let lba = off as usize / LBA_SIZE; let mut v: Vec = Vec::new(); v.resize(LBA_SIZE, 0); partition.disk().read_at(lba, 1, &mut v)?; let mut cursor: VecCursor = VecCursor::new(v); cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; self.lead_sig = cursor.read_u32()?; cursor.seek(SeekFrom::SeekCurrent(480))?; self.struc_sig = cursor.read_u32()?; self.free_count = cursor.read_u32()?; self.next_free = cursor.read_u32()?; cursor.seek(SeekFrom::SeekCurrent(12))?; self.trail_sig = cursor.read_u32()?; } return Ok(()); } } impl IndexNode for LockedFATInode { fn read_at( &self, offset: usize, len: usize, buf: &mut [u8], _data: &mut FilePrivateData, ) -> Result { let mut guard: SpinLockGuard = self.0.lock(); match &guard.inode_type { FATDirEntry::File(f) | FATDirEntry::VolId(f) => { let r = f.read( &guard.fs.upgrade().unwrap(), &mut buf[0..len], offset as u64, ); guard.update_metadata(); return r; } FATDirEntry::Dir(_) => { return Err(-(EISDIR as i32)); } FATDirEntry::UnInit => { kerror!("FATFS: param: Inode_type uninitialized."); return Err(-(EROFS as i32)); } } } fn write_at( &self, offset: usize, len: usize, buf: &[u8], _data: &mut FilePrivateData, ) -> Result { let mut guard: SpinLockGuard = self.0.lock(); let fs: &Arc = &guard.fs.upgrade().unwrap(); match &mut guard.inode_type { FATDirEntry::File(f) | FATDirEntry::VolId(f) => { let r = f.write(fs, &buf[0..len], offset as u64); guard.update_metadata(); return r; } FATDirEntry::Dir(_) => { return Err(-(EISDIR as i32)); } FATDirEntry::UnInit => { kerror!("FATFS: param: Inode_type uninitialized."); return Err(-(EROFS as i32)); } } } fn poll(&self) -> Result { // 加锁 let inode: SpinLockGuard = self.0.lock(); // 检查当前inode是否为一个文件夹，如果是的话，就返回错误 if inode.metadata.file_type == FileType::Dir { return Err(-(EISDIR as i32)); } return Ok(PollStatus { flags: PollStatus::READ_MASK | PollStatus::WRITE_MASK, }); } fn create( &self, name: &str, file_type: FileType, _mode: u32, ) -> Result, i32> { // 由于FAT32不支持文件权限的功能，因此忽略mode参数 let mut guard: SpinLockGuard = self.0.lock(); let fs: &Arc = &guard.fs.upgrade().unwrap(); match &mut guard.inode_type { FATDirEntry::File(_) | FATDirEntry::VolId(_) => { return Err(-(ENOTDIR as i32)); } FATDirEntry::Dir(d) => match file_type { FileType::File => { d.create_file(name, fs)?; return Ok(guard.find(name)?); } FileType::Dir => { d.create_dir(name, fs)?; return Ok(guard.find(name)?); } FileType::SymLink => return Err(-(ENOTSUP as i32)), _ => return Err(-(EINVAL as i32)), }, FATDirEntry::UnInit => { kerror!("FATFS: param: Inode_type uninitialized."); return Err(-(EROFS as i32)); } } } fn fs(&self) -> Arc { return self.0.lock().fs.upgrade().unwrap(); } fn as_any_ref(&self) -> &dyn core::any::Any { return self; } fn metadata(&self) -> Result { return Ok(self.0.lock().metadata.clone()); } fn list(&self) -> Result, i32> { let mut guard: SpinLockGuard = self.0.lock(); let fatent: &FATDirEntry = &guard.inode_type; match fatent { FATDirEntry::File(_) | FATDirEntry::VolId(_) => { return Err(-(ENOTDIR as i32)); } FATDirEntry::Dir(dir) => { // 获取当前目录下的所有目录项 let mut ret: Vec = Vec::new(); let dir_iter: FATDirIter = dir.to_iter(guard.fs.upgrade().unwrap()); for ent in dir_iter { ret.push(ent.name()); // ====== 生成inode缓存，存入B树 let name: String = ent.name(); // kdebug!("name={name}"); if guard.children.contains_key(&name.to_uppercase()) == false && name != "." && name != ".." { // 创建新的inode let entry_inode: Arc = LockedFATInode::new( guard.fs.upgrade().unwrap(), guard.self_ref.clone(), ent, ); // 加入缓存区, 由于FAT文件系统的大小写不敏感问题，因此存入缓存区的key应当是全大写的 guard .children .insert(name.to_uppercase(), entry_inode.clone()); } } return Ok(ret); } FATDirEntry::UnInit => { kerror!("FATFS: param: Inode_type uninitialized."); return Err(-(EROFS as i32)); } } } fn find(&self, name: &str) -> Result, i32> { let mut guard: SpinLockGuard = self.0.lock(); let target = guard.find(name)?; return Ok(target); } fn open(&self, _data: &mut FilePrivateData, _mode: &FileMode) -> Result<(), i32> { return Ok(()); } fn close(&self, _data: &mut FilePrivateData) -> Result<(), i32> { return Ok(()); } fn unlink(&self, name: &str) -> Result<(), i32> { let mut guard: SpinLockGuard = self.0.lock(); let target: Arc = guard.find(name)?; // 对目标inode上锁，以防更改 let target_guard: SpinLockGuard = target.0.lock(); // 先从缓存删除 guard.children.remove(&name.to_uppercase()); let dir = match &guard.inode_type { FATDirEntry::File(_) | FATDirEntry::VolId(_) => { return Err(-(ENOTDIR as i32)); } FATDirEntry::Dir(d) => d, FATDirEntry::UnInit => { kerror!("FATFS: param: Inode_type uninitialized."); return Err(-(EROFS as i32)); } }; // 检查文件是否存在 dir.check_existence(name, Some(false), guard.fs.upgrade().unwrap())?; // 再从磁盘删除 let r = dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); drop(target_guard); return r; } fn rmdir(&self, name: &str) -> Result<(), i32> { let mut guard: SpinLockGuard = self.0.lock(); let target: Arc = guard.find(name)?; // 对目标inode上锁，以防更改 let target_guard: SpinLockGuard = target.0.lock(); // 先从缓存删除 guard.children.remove(&name.to_uppercase()); let dir = match &guard.inode_type { FATDirEntry::File(_) | FATDirEntry::VolId(_) => { return Err(-(ENOTDIR as i32)); } FATDirEntry::Dir(d) => d, FATDirEntry::UnInit => { kerror!("FATFS: param: Inode_type uninitialized."); return Err(-(EROFS as i32)); } }; // 检查文件夹是否存在 dir.check_existence(name, Some(true), guard.fs.upgrade().unwrap())?; // 再从磁盘删除 let r: Result<(), i32> = dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); if r.is_ok() { return r; } else { let r = r.unwrap_err(); if r == -(ENOTEMPTY as i32) { // 如果要删除的是目录，且不为空，则删除动作未发生，重新加入缓存 guard.children.insert(name.to_uppercase(), target.clone()); drop(target_guard); } return Err(r); } } fn get_entry_name(&self, ino: InodeId) -> Result { let guard: SpinLockGuard = self.0.lock(); if guard.metadata.file_type != FileType::Dir { return Err(-(ENOTDIR as i32)); } match ino { 0 => { return Ok(String::from(".")); } 1 => { return Ok(String::from("..")); } ino => { // 暴力遍历所有的children，判断inode id是否相同 // TODO: 优化这里，这个地方性能很差！ let mut key: Vec = guard .children .keys() .filter(|k| guard.children.get(*k).unwrap().metadata().unwrap().inode_id == ino) .cloned() .collect(); match key.len() { 0=>{return Err(-(ENOENT as i32));} 1=>{return Ok(key.remove(0));} _ => panic!("FatFS get_entry_name: key.len()={key_len}>1, current inode_id={inode_id}, to find={to_find}", key_len=key.len(), inode_id = guard.metadata.inode_id, to_find=ino) } } } } } impl Default for FATFsInfo { fn default() -> Self { return FATFsInfo { lead_sig: FATFsInfo::LEAD_SIG, struc_sig: FATFsInfo::STRUC_SIG, free_count: 0xFFFFFFFF, next_free: RESERVED_CLUSTERS, trail_sig: FATFsInfo::TRAIL_SIG, dirty: false, offset: None, }; } } impl Cluster { pub fn new(cluster: u64) -> Self { return Cluster { cluster_num: cluster, parent_cluster: 0, }; } } /// @brief 用于迭代FAT表的内容的簇迭代器对象 #[derive(Debug)] struct ClusterIter<'a> { /// 迭代器的next要返回的簇 current_cluster: Option, /// 属于的文件系统 fs: &'a FATFileSystem, } impl<'a> Iterator for ClusterIter<'a> { type Item = Cluster; fn next(&mut self) -> Option { // 当前要返回的簇 let ret: Option = self.current_cluster; // 获得下一个要返回簇 let new: Option = match self.current_cluster { Some(c) => { let entry: Option = self.fs.get_fat_entry(c).ok(); match entry { Some(FATEntry::Next(c)) => Some(c), _ => None, } } _ => None, }; self.current_cluster = new; return ret; } }