1 use core::intrinsics::unlikely; 2 use core::{any::Any, fmt::Debug}; 3 use system_error::SystemError; 4 5 use alloc::{ 6 collections::BTreeMap, 7 string::String, 8 sync::{Arc, Weak}, 9 vec::Vec, 10 }; 11 12 use crate::driver::base::device::device_number::DeviceNumber; 13 use crate::filesystem::vfs::SpecialNodeData; 14 use crate::ipc::pipe::LockedPipeInode; 15 use crate::{ 16 driver::base::block::{block_device::LBA_SIZE, disk_info::Partition, SeekFrom}, 17 filesystem::vfs::{ 18 core::generate_inode_id, 19 file::{FileMode, FilePrivateData}, 20 syscall::ModeType, 21 FileSystem, FileType, IndexNode, InodeId, Metadata, 22 }, 23 kerror, 24 libs::{ 25 spinlock::{SpinLock, SpinLockGuard}, 26 vec_cursor::VecCursor, 27 }, 28 time::TimeSpec, 29 }; 30 31 use super::entry::FATFile; 32 use super::{ 33 bpb::{BiosParameterBlock, FATType}, 34 entry::{FATDir, FATDirEntry, FATDirIter, FATEntry}, 35 utils::RESERVED_CLUSTERS, 36 }; 37 38 /// FAT32文件系统的最大的文件大小 39 pub const MAX_FILE_SIZE: u64 = 0xffff_ffff; 40 41 /// @brief 表示当前簇和上一个簇的关系的结构体 42 /// 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。 43 #[derive(Debug, Clone, Copy, Default)] 44 pub struct Cluster { 45 pub cluster_num: u64, 46 pub parent_cluster: u64, 47 } 48 49 impl PartialOrd for Cluster { 50 /// @brief 根据当前簇号比较大小 partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering>51 fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> { 52 return self.cluster_num.partial_cmp(&other.cluster_num); 53 } 54 } 55 56 impl PartialEq for Cluster { 57 /// @brief 根据当前簇号比较是否相等 eq(&self, other: &Self) -> bool58 fn eq(&self, other: &Self) -> bool { 59 self.cluster_num == other.cluster_num 60 } 61 } 62 63 impl Eq for Cluster {} 64 65 #[derive(Debug)] 66 pub struct FATFileSystem { 67 /// 当前文件系统所在的分区 68 pub partition: Arc<Partition>, 69 /// 当前文件系统的BOPB 70 pub bpb: BiosParameterBlock, 71 /// 当前文件系统的第一个数据扇区（相对分区开始位置） 72 pub first_data_sector: u64, 73 /// 文件系统信息结构体 74 pub fs_info: Arc<LockedFATFsInfo>, 75 /// 文件系统的根inode 76 root_inode: Arc<LockedFATInode>, 77 } 78 79 /// FAT文件系统的Inode 80 #[derive(Debug)] 81 pub struct LockedFATInode(SpinLock<FATInode>); 82 83 #[derive(Debug)] 84 pub struct LockedFATFsInfo(SpinLock<FATFsInfo>); 85 86 impl LockedFATFsInfo { 87 #[inline] new(fs_info: FATFsInfo) -> Self88 pub fn new(fs_info: FATFsInfo) -> Self { 89 return Self(SpinLock::new(fs_info)); 90 } 91 } 92 93 #[derive(Debug)] 94 pub struct FATInode { 95 /// 指向父Inode的弱引用 96 parent: Weak<LockedFATInode>, 97 /// 指向自身的弱引用 98 self_ref: Weak<LockedFATInode>, 99 /// 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。 100 /// 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。 101 children: BTreeMap<String, Arc<LockedFATInode>>, 102 /// 当前inode的元数据 103 metadata: Metadata, 104 /// 指向inode所在的文件系统对象的指针 105 fs: Weak<FATFileSystem>, 106 107 /// 根据不同的Inode类型，创建不同的私有字段 108 inode_type: FATDirEntry, 109 110 /// 若该节点是特殊文件节点，该字段则为真正的文件节点 111 special_node: Option<SpecialNodeData>, 112 } 113 114 impl FATInode { 115 /// @brief 更新当前inode的元数据 update_metadata(&mut self)116 pub fn update_metadata(&mut self) { 117 // todo: 更新文件的访问时间等信息 118 match &self.inode_type { 119 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 120 self.metadata.size = f.size() as i64; 121 } 122 FATDirEntry::Dir(d) => { 123 self.metadata.size = d.size(&self.fs.upgrade().unwrap().clone()) as i64; 124 } 125 FATDirEntry::UnInit => { 126 kerror!("update_metadata: Uninitialized FATDirEntry: {:?}", self); 127 return; 128 } 129 }; 130 } 131 find(&mut self, name: &str) -> Result<Arc<LockedFATInode>, SystemError>132 fn find(&mut self, name: &str) -> Result<Arc<LockedFATInode>, SystemError> { 133 match &self.inode_type { 134 FATDirEntry::Dir(d) => { 135 // 尝试在缓存区查找 136 if let Some(entry) = self.children.get(&name.to_uppercase()) { 137 return Ok(entry.clone()); 138 } 139 // 在缓存区找不到 140 // 在磁盘查找 141 let fat_entry: FATDirEntry = 142 d.find_entry(name, None, None, self.fs.upgrade().unwrap())?; 143 // kdebug!("find entry from disk ok, entry={fat_entry:?}"); 144 // 创建新的inode 145 let entry_inode: Arc<LockedFATInode> = LockedFATInode::new( 146 self.fs.upgrade().unwrap(), 147 self.self_ref.clone(), 148 fat_entry, 149 ); 150 // 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 151 self.children 152 .insert(name.to_uppercase(), entry_inode.clone()); 153 return Ok(entry_inode); 154 } 155 FATDirEntry::UnInit => { 156 panic!( 157 "Uninitialized FAT Inode, fs = {:?}, inode={self:?}", 158 self.fs 159 ) 160 } 161 _ => { 162 return Err(SystemError::ENOTDIR); 163 } 164 } 165 } 166 } 167 168 impl LockedFATInode { new( fs: Arc<FATFileSystem>, parent: Weak<LockedFATInode>, inode_type: FATDirEntry, ) -> Arc<LockedFATInode>169 pub fn new( 170 fs: Arc<FATFileSystem>, 171 parent: Weak<LockedFATInode>, 172 inode_type: FATDirEntry, 173 ) -> Arc<LockedFATInode> { 174 let file_type = if let FATDirEntry::Dir(_) = inode_type { 175 FileType::Dir 176 } else { 177 FileType::File 178 }; 179 180 let inode: Arc<LockedFATInode> = Arc::new(LockedFATInode(SpinLock::new(FATInode { 181 parent: parent, 182 self_ref: Weak::default(), 183 children: BTreeMap::new(), 184 fs: Arc::downgrade(&fs), 185 inode_type: inode_type, 186 metadata: Metadata { 187 dev_id: 0, 188 inode_id: generate_inode_id(), 189 size: 0, 190 blk_size: fs.bpb.bytes_per_sector as usize, 191 blocks: if let FATType::FAT32(_) = fs.bpb.fat_type { 192 fs.bpb.total_sectors_32 as usize 193 } else { 194 fs.bpb.total_sectors_16 as usize 195 }, 196 atime: TimeSpec::default(), 197 mtime: TimeSpec::default(), 198 ctime: TimeSpec::default(), 199 file_type: file_type, 200 mode: ModeType::from_bits_truncate(0o777), 201 nlinks: 1, 202 uid: 0, 203 gid: 0, 204 raw_dev: DeviceNumber::default(), 205 }, 206 special_node: None, 207 }))); 208 209 inode.0.lock().self_ref = Arc::downgrade(&inode); 210 211 inode.0.lock().update_metadata(); 212 213 return inode; 214 } 215 } 216 217 /// 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） 218 #[derive(Debug)] 219 pub struct FATFsInfo { 220 /// Lead Signature - must equal 0x41615252 221 lead_sig: u32, 222 /// Value must equal 0x61417272 223 struc_sig: u32, 224 /// 空闲簇数目 225 free_count: u32, 226 /// 第一个空闲簇的位置（不一定准确，仅供加速查找） 227 next_free: u32, 228 /// 0xAA550000 229 trail_sig: u32, 230 /// Dirty flag to flush to disk 231 dirty: bool, 232 /// FsInfo Structure 在磁盘上的字节偏移量 233 /// Not present for FAT12 and FAT16 234 offset: Option<u64>, 235 } 236 237 impl FileSystem for FATFileSystem { root_inode(&self) -> Arc<dyn crate::filesystem::vfs::IndexNode>238 fn root_inode(&self) -> Arc<dyn crate::filesystem::vfs::IndexNode> { 239 return self.root_inode.clone(); 240 } 241 info(&self) -> crate::filesystem::vfs::FsInfo242 fn info(&self) -> crate::filesystem::vfs::FsInfo { 243 todo!() 244 } 245 246 /// @brief 本函数用于实现动态转换。 247 /// 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 as_any_ref(&self) -> &dyn Any248 fn as_any_ref(&self) -> &dyn Any { 249 self 250 } 251 } 252 253 impl FATFileSystem { 254 /// FAT12允许的最大簇号 255 pub const FAT12_MAX_CLUSTER: u32 = 0xFF5; 256 /// FAT16允许的最大簇号 257 pub const FAT16_MAX_CLUSTER: u32 = 0xFFF5; 258 /// FAT32允许的最大簇号 259 pub const FAT32_MAX_CLUSTER: u32 = 0x0FFFFFF7; 260 new(partition: Arc<Partition>) -> Result<Arc<FATFileSystem>, SystemError>261 pub fn new(partition: Arc<Partition>) -> Result<Arc<FATFileSystem>, SystemError> { 262 let bpb = BiosParameterBlock::new(partition.clone())?; 263 264 // 从磁盘上读取FAT32文件系统的FsInfo结构体 265 let fs_info: FATFsInfo = match bpb.fat_type { 266 FATType::FAT32(bpb32) => { 267 let fs_info_in_disk_bytes_offset = partition.lba_start * LBA_SIZE as u64 268 + bpb32.fs_info as u64 * bpb.bytes_per_sector as u64; 269 FATFsInfo::new( 270 partition.clone(), 271 fs_info_in_disk_bytes_offset, 272 bpb.bytes_per_sector as usize, 273 )? 274 } 275 _ => FATFsInfo::default(), 276 }; 277 278 // 根目录项占用的扇区数（向上取整） 279 let root_dir_sectors: u64 = ((bpb.root_entries_cnt as u64 * 32) 280 + (bpb.bytes_per_sector as u64 - 1)) 281 / (bpb.bytes_per_sector as u64); 282 283 // FAT表大小（单位：扇区） 284 let fat_size = if bpb.fat_size_16 != 0 { 285 bpb.fat_size_16 as u64 286 } else { 287 match bpb.fat_type { 288 FATType::FAT32(x) => x.fat_size_32 as u64, 289 _ => { 290 kerror!("FAT12 and FAT16 volumes should have non-zero BPB_FATSz16"); 291 return Err(SystemError::EINVAL); 292 } 293 } 294 }; 295 296 let first_data_sector = 297 bpb.rsvd_sec_cnt as u64 + (bpb.num_fats as u64 * fat_size) + root_dir_sectors; 298 299 // 创建文件系统的根节点 300 let root_inode: Arc<LockedFATInode> = Arc::new(LockedFATInode(SpinLock::new(FATInode { 301 parent: Weak::default(), 302 self_ref: Weak::default(), 303 children: BTreeMap::new(), 304 fs: Weak::default(), 305 inode_type: FATDirEntry::UnInit, 306 metadata: Metadata { 307 dev_id: 0, 308 inode_id: generate_inode_id(), 309 size: 0, 310 blk_size: bpb.bytes_per_sector as usize, 311 blocks: if let FATType::FAT32(_) = bpb.fat_type { 312 bpb.total_sectors_32 as usize 313 } else { 314 bpb.total_sectors_16 as usize 315 }, 316 atime: TimeSpec::default(), 317 mtime: TimeSpec::default(), 318 ctime: TimeSpec::default(), 319 file_type: FileType::Dir, 320 mode: ModeType::from_bits_truncate(0o777), 321 nlinks: 1, 322 uid: 0, 323 gid: 0, 324 raw_dev: DeviceNumber::default(), 325 }, 326 special_node: None, 327 }))); 328 329 let result: Arc<FATFileSystem> = Arc::new(FATFileSystem { 330 partition: partition, 331 bpb, 332 first_data_sector, 333 fs_info: Arc::new(LockedFATFsInfo::new(fs_info)), 334 root_inode: root_inode, 335 }); 336 337 // 对root inode加锁，并继续完成初始化工作 338 let mut root_guard: SpinLockGuard<FATInode> = result.root_inode.0.lock(); 339 root_guard.inode_type = FATDirEntry::Dir(result.root_dir()); 340 root_guard.parent = Arc::downgrade(&result.root_inode); 341 root_guard.self_ref = Arc::downgrade(&result.root_inode); 342 root_guard.fs = Arc::downgrade(&result); 343 // 释放锁 344 drop(root_guard); 345 346 return Ok(result); 347 } 348 349 /// @brief 计算每个簇有多少个字节 350 #[inline] bytes_per_cluster(&self) -> u64351 pub fn bytes_per_cluster(&self) -> u64 { 352 return (self.bpb.bytes_per_sector as u64) * (self.bpb.sector_per_cluster as u64); 353 } 354 355 /// @brief 读取当前簇在FAT表中存储的信息 356 /// 357 /// @param cluster 当前簇 358 /// 359 /// @return Ok(FATEntry) 当前簇在FAT表中，存储的信息。（详情见FATEntry的注释） 360 /// @return Err(SystemError) 错误码 get_fat_entry(&self, cluster: Cluster) -> Result<FATEntry, SystemError>361 pub fn get_fat_entry(&self, cluster: Cluster) -> Result<FATEntry, SystemError> { 362 let current_cluster = cluster.cluster_num; 363 if current_cluster < 2 { 364 // 0号簇和1号簇是保留簇，不允许用户使用 365 return Err(SystemError::EINVAL); 366 } 367 368 let fat_type: FATType = self.bpb.fat_type; 369 // 获取FAT表的起始扇区（相对分区起始扇区的偏移量） 370 let fat_start_sector = self.fat_start_sector(); 371 let bytes_per_sec = self.bpb.bytes_per_sector as u64; 372 373 // cluster对应的FAT表项在分区内的字节偏移量 374 let fat_bytes_offset = 375 fat_type.get_fat_bytes_offset(cluster, fat_start_sector, bytes_per_sec); 376 377 // FAT表项所在的LBA地址 378 // let fat_ent_lba = self.get_lba_from_offset(self.bytes_to_sector(fat_bytes_offset)); 379 let fat_ent_lba = self.partition.lba_start + fat_bytes_offset / LBA_SIZE as u64; 380 381 // FAT表项在逻辑块内的字节偏移量 382 let blk_offset = self.get_in_block_offset(fat_bytes_offset); 383 384 let mut v = Vec::<u8>::new(); 385 v.resize(self.bpb.bytes_per_sector as usize, 0); 386 self.partition 387 .disk() 388 .read_at(fat_ent_lba as usize, 1 * self.lba_per_sector(), &mut v)?; 389 390 let mut cursor = VecCursor::new(v); 391 cursor.seek(SeekFrom::SeekSet(blk_offset as i64))?; 392 393 let res: FATEntry = match self.bpb.fat_type { 394 FATType::FAT12(_) => { 395 let mut entry = cursor.read_u16()?; 396 // 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。 397 if (current_cluster & 1) > 0 { 398 entry >>= 4; 399 } else { 400 entry &= 0x0fff; 401 } 402 403 if entry == 0 { 404 FATEntry::Unused 405 } else if entry == 0x0ff7 { 406 FATEntry::Bad 407 } else if entry >= 0x0ff8 { 408 FATEntry::EndOfChain 409 } else { 410 FATEntry::Next(Cluster { 411 cluster_num: entry as u64, 412 parent_cluster: current_cluster, 413 }) 414 } 415 } 416 FATType::FAT16(_) => { 417 let entry = cursor.read_u16()?; 418 419 if entry == 0 { 420 FATEntry::Unused 421 } else if entry == 0xfff7 { 422 FATEntry::Bad 423 } else if entry >= 0xfff8 { 424 FATEntry::EndOfChain 425 } else { 426 FATEntry::Next(Cluster { 427 cluster_num: entry as u64, 428 parent_cluster: current_cluster, 429 }) 430 } 431 } 432 FATType::FAT32(_) => { 433 let entry = cursor.read_u32()? & 0x0fffffff; 434 435 match entry { 436 _n if (current_cluster >= 0x0ffffff7 && current_cluster <= 0x0fffffff) => { 437 // 当前簇号不是一个能被获得的簇（可能是文件系统出错了） 438 kerror!("FAT32 get fat entry: current cluster number [{}] is not an allocatable cluster number.", current_cluster); 439 FATEntry::Bad 440 } 441 0 => FATEntry::Unused, 442 0x0ffffff7 => FATEntry::Bad, 443 0x0ffffff8..=0x0fffffff => FATEntry::EndOfChain, 444 _n => FATEntry::Next(Cluster { 445 cluster_num: entry as u64, 446 parent_cluster: current_cluster, 447 }), 448 } 449 } 450 }; 451 return Ok(res); 452 } 453 454 /// @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） 455 /// 456 /// @param cluster 当前簇 457 /// 458 /// @return Ok(u64) 当前簇在FAT表中，存储的信息。 459 /// @return Err(SystemError) 错误码 get_fat_entry_raw(&self, cluster: Cluster) -> Result<u64, SystemError>460 pub fn get_fat_entry_raw(&self, cluster: Cluster) -> Result<u64, SystemError> { 461 let current_cluster = cluster.cluster_num; 462 463 let fat_type: FATType = self.bpb.fat_type; 464 // 获取FAT表的起始扇区（相对分区起始扇区的偏移量） 465 let fat_start_sector = self.fat_start_sector(); 466 let bytes_per_sec = self.bpb.bytes_per_sector as u64; 467 468 // cluster对应的FAT表项在分区内的字节偏移量 469 let fat_bytes_offset = 470 fat_type.get_fat_bytes_offset(cluster, fat_start_sector, bytes_per_sec); 471 472 // FAT表项所在的LBA地址 473 let fat_ent_lba = self.get_lba_from_offset(self.bytes_to_sector(fat_bytes_offset)); 474 475 // FAT表项在逻辑块内的字节偏移量 476 let blk_offset = self.get_in_block_offset(fat_bytes_offset); 477 478 let mut v = Vec::<u8>::new(); 479 v.resize(self.bpb.bytes_per_sector as usize, 0); 480 self.partition 481 .disk() 482 .read_at(fat_ent_lba, 1 * self.lba_per_sector(), &mut v)?; 483 484 let mut cursor = VecCursor::new(v); 485 cursor.seek(SeekFrom::SeekSet(blk_offset as i64))?; 486 487 let res = match self.bpb.fat_type { 488 FATType::FAT12(_) => { 489 let mut entry = cursor.read_u16()?; 490 entry = if (current_cluster & 0x0001) > 0 { 491 entry >> 4 492 } else { 493 entry & 0x0fff 494 }; 495 entry as u64 496 } 497 FATType::FAT16(_) => { 498 let entry = (cursor.read_u16()?) as u64; 499 entry 500 } 501 FATType::FAT32(_) => { 502 let entry = cursor.read_u32()? & 0x0fff_ffff; 503 entry as u64 504 } 505 }; 506 507 return Ok(res); 508 } 509 510 /// @brief 获取当前文件系统的root inode，在磁盘上的字节偏移量 root_dir_bytes_offset(&self) -> u64511 pub fn root_dir_bytes_offset(&self) -> u64 { 512 match self.bpb.fat_type { 513 FATType::FAT32(s) => { 514 let first_sec_cluster: u64 = (s.root_cluster as u64 - 2) 515 * (self.bpb.sector_per_cluster as u64) 516 + self.first_data_sector; 517 return (self.get_lba_from_offset(first_sec_cluster) * LBA_SIZE) as u64; 518 } 519 _ => { 520 let root_sec = (self.bpb.rsvd_sec_cnt as u64) 521 + (self.bpb.num_fats as u64) * (self.bpb.fat_size_16 as u64); 522 return (self.get_lba_from_offset(root_sec) * LBA_SIZE) as u64; 523 } 524 } 525 } 526 527 /// @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。 528 /// 请注意，当前函数只对FAT12/FAT16生效。对于FAT32,返回None root_dir_end_bytes_offset(&self) -> Option<u64>529 pub fn root_dir_end_bytes_offset(&self) -> Option<u64> { 530 match self.bpb.fat_type { 531 FATType::FAT12(_) | FATType::FAT16(_) => { 532 return Some( 533 self.root_dir_bytes_offset() + (self.bpb.root_entries_cnt as u64) * 32, 534 ); 535 } 536 _ => { 537 return None; 538 } 539 } 540 } 541 542 /// @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) cluster_bytes_offset(&self, cluster: Cluster) -> u64543 pub fn cluster_bytes_offset(&self, cluster: Cluster) -> u64 { 544 if cluster.cluster_num >= 2 { 545 // 指定簇的第一个扇区号 546 let first_sec_of_cluster = (cluster.cluster_num - 2) 547 * (self.bpb.sector_per_cluster as u64) 548 + self.first_data_sector; 549 return (self.get_lba_from_offset(first_sec_of_cluster) * LBA_SIZE) as u64; 550 } else { 551 return 0; 552 } 553 } 554 555 /// @brief 获取一个空闲簇 556 /// 557 /// @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。 558 /// 559 /// @return Ok(Cluster) 新获取的空闲簇 560 /// @return Err(SystemError) 错误码 allocate_cluster(&self, prev_cluster: Option<Cluster>) -> Result<Cluster, SystemError>561 pub fn allocate_cluster(&self, prev_cluster: Option<Cluster>) -> Result<Cluster, SystemError> { 562 let end_cluster: Cluster = self.max_cluster_number(); 563 let start_cluster: Cluster = match self.bpb.fat_type { 564 FATType::FAT32(_) => { 565 let next_free: u64 = match self.fs_info.0.lock().next_free() { 566 Some(x) => x, 567 None => 0xffffffff, 568 }; 569 if next_free < end_cluster.cluster_num { 570 Cluster::new(next_free) 571 } else { 572 Cluster::new(RESERVED_CLUSTERS as u64) 573 } 574 } 575 _ => Cluster::new(RESERVED_CLUSTERS as u64), 576 }; 577 578 // 寻找一个空的簇 579 let free_cluster: Cluster = match self.get_free_cluster(start_cluster, end_cluster) { 580 Ok(c) => c, 581 Err(_) if start_cluster.cluster_num > RESERVED_CLUSTERS as u64 => { 582 self.get_free_cluster(Cluster::new(RESERVED_CLUSTERS as u64), end_cluster)? 583 } 584 Err(e) => return Err(e), 585 }; 586 587 self.set_entry(free_cluster, FATEntry::EndOfChain)?; 588 // 减少空闲簇计数 589 self.fs_info.0.lock().update_free_count_delta(-1); 590 // 更新搜索空闲簇的参考量 591 self.fs_info 592 .0 593 .lock() 594 .update_next_free((free_cluster.cluster_num + 1) as u32); 595 596 // 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。 597 if let Some(prev_cluster) = prev_cluster { 598 // kdebug!("set entry, prev ={prev_cluster:?}, next = {free_cluster:?}"); 599 self.set_entry(prev_cluster, FATEntry::Next(free_cluster))?; 600 } 601 // 清空新获取的这个簇 602 self.zero_cluster(free_cluster)?; 603 return Ok(free_cluster); 604 } 605 606 /// @brief 释放簇链上的所有簇 607 /// 608 /// @param start_cluster 簇链的第一个簇 deallocate_cluster_chain(&self, start_cluster: Cluster) -> Result<(), SystemError>609 pub fn deallocate_cluster_chain(&self, start_cluster: Cluster) -> Result<(), SystemError> { 610 let clusters: Vec<Cluster> = self.clusters(start_cluster); 611 for c in clusters { 612 self.deallocate_cluster(c)?; 613 } 614 return Ok(()); 615 } 616 617 /// @brief 释放簇 618 /// 619 /// @param 要释放的簇 deallocate_cluster(&self, cluster: Cluster) -> Result<(), SystemError>620 pub fn deallocate_cluster(&self, cluster: Cluster) -> Result<(), SystemError> { 621 let entry: FATEntry = self.get_fat_entry(cluster)?; 622 // 如果不是坏簇 623 if entry != FATEntry::Bad { 624 self.set_entry(cluster, FATEntry::Unused)?; 625 self.fs_info.0.lock().update_free_count_delta(1); 626 // 安全选项：清空被释放的簇 627 #[cfg(feature = "secure")] 628 self.zero_cluster(cluster)?; 629 return Ok(()); 630 } else { 631 // 不能释放坏簇 632 kerror!("Bad clusters cannot be freed."); 633 return Err(SystemError::EFAULT); 634 } 635 } 636 637 /// @brief 获取文件系统的根目录项 root_dir(&self) -> FATDir638 pub fn root_dir(&self) -> FATDir { 639 match self.bpb.fat_type { 640 FATType::FAT32(s) => { 641 return FATDir { 642 first_cluster: Cluster::new(s.root_cluster as u64), 643 dir_name: String::from("/"), 644 root_offset: None, 645 short_dir_entry: None, 646 loc: None, 647 }; 648 } 649 _ => FATDir { 650 first_cluster: Cluster::new(0), 651 dir_name: String::from("/"), 652 root_offset: Some(self.root_dir_bytes_offset()), 653 short_dir_entry: None, 654 loc: None, 655 }, 656 } 657 } 658 659 /// @brief 获取FAT表的起始扇区（相对分区起始扇区的偏移量） fat_start_sector(&self) -> u64660 pub fn fat_start_sector(&self) -> u64 { 661 let active_fat = self.active_fat(); 662 let fat_size = self.fat_size(); 663 return self.bpb.rsvd_sec_cnt as u64 + active_fat * fat_size; 664 } 665 666 /// @brief 获取当前活动的FAT表 active_fat(&self) -> u64667 pub fn active_fat(&self) -> u64 { 668 if self.mirroring_enabled() { 669 return 0; 670 } else { 671 match self.bpb.fat_type { 672 FATType::FAT32(bpb32) => { 673 return (bpb32.ext_flags & 0x0f) as u64; 674 } 675 _ => { 676 return 0; 677 } 678 } 679 } 680 } 681 682 /// @brief 获取当前文件系统的每个FAT表的大小 fat_size(&self) -> u64683 pub fn fat_size(&self) -> u64 { 684 if self.bpb.fat_size_16 != 0 { 685 return self.bpb.fat_size_16 as u64; 686 } else { 687 match self.bpb.fat_type { 688 FATType::FAT32(bpb32) => { 689 return bpb32.fat_size_32 as u64; 690 } 691 692 _ => { 693 panic!("FAT12 and FAT16 volumes should have non-zero BPB_FATSz16"); 694 } 695 } 696 } 697 } 698 699 /// @brief 判断当前文件系统是否启用了FAT表镜像 mirroring_enabled(&self) -> bool700 pub fn mirroring_enabled(&self) -> bool { 701 match self.bpb.fat_type { 702 FATType::FAT32(bpb32) => { 703 return (bpb32.ext_flags & 0x80) == 0; 704 } 705 _ => { 706 return false; 707 } 708 } 709 } 710 711 /// @brief 根据分区内的扇区偏移量，获得在磁盘上的LBA地址 712 #[inline] get_lba_from_offset(&self, in_partition_sec_offset: u64) -> usize713 pub fn get_lba_from_offset(&self, in_partition_sec_offset: u64) -> usize { 714 return (self.partition.lba_start 715 + in_partition_sec_offset * (self.bpb.bytes_per_sector as u64 / LBA_SIZE as u64)) 716 as usize; 717 } 718 719 /// @brief 获取每个扇区占用多少个LBA 720 #[inline] lba_per_sector(&self) -> usize721 pub fn lba_per_sector(&self) -> usize { 722 return self.bpb.bytes_per_sector as usize / LBA_SIZE; 723 } 724 725 /// @brief 将分区内字节偏移量转换为扇区偏移量 726 #[inline] bytes_to_sector(&self, in_partition_bytes_offset: u64) -> u64727 pub fn bytes_to_sector(&self, in_partition_bytes_offset: u64) -> u64 { 728 return in_partition_bytes_offset / (self.bpb.bytes_per_sector as u64); 729 } 730 731 /// @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 732 #[inline] get_in_partition_bytes_offset(&self, disk_bytes_offset: u64) -> u64733 pub fn get_in_partition_bytes_offset(&self, disk_bytes_offset: u64) -> u64 { 734 return disk_bytes_offset - (self.partition.lba_start * LBA_SIZE as u64); 735 } 736 737 /// @brief 根据字节偏移量计算在逻辑块内的字节偏移量 738 #[inline] get_in_block_offset(&self, bytes_offset: u64) -> u64739 pub fn get_in_block_offset(&self, bytes_offset: u64) -> u64 { 740 return bytes_offset % LBA_SIZE as u64; 741 } 742 743 /// @brief 获取在FAT表中，以start_cluster开头的FAT链的所有簇的信息 744 /// 745 /// @param start_cluster 整个FAT链的起始簇号 clusters(&self, start_cluster: Cluster) -> Vec<Cluster>746 pub fn clusters(&self, start_cluster: Cluster) -> Vec<Cluster> { 747 return self.cluster_iter(start_cluster).collect(); 748 } 749 750 /// @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） 751 /// 752 /// @param start_cluster 整个FAT链的起始簇号 num_clusters_chain(&self, start_cluster: Cluster) -> u64753 pub fn num_clusters_chain(&self, start_cluster: Cluster) -> u64 { 754 return self 755 .cluster_iter(start_cluster) 756 .fold(0, |size, _cluster| size + 1); 757 } 758 /// @brief 获取一个簇迭代器对象 759 /// 760 /// @param start_cluster 整个FAT链的起始簇号 cluster_iter(&self, start_cluster: Cluster) -> ClusterIter761 fn cluster_iter(&self, start_cluster: Cluster) -> ClusterIter { 762 return ClusterIter { 763 current_cluster: Some(start_cluster), 764 fs: self, 765 }; 766 } 767 768 /// @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） 769 #[inline] get_cluster_by_relative(&self, start_cluster: Cluster, n: usize) -> Option<Cluster>770 pub fn get_cluster_by_relative(&self, start_cluster: Cluster, n: usize) -> Option<Cluster> { 771 return self.cluster_iter(start_cluster).skip(n).next(); 772 } 773 774 /// @brief 获取整个簇链的最后一个簇 775 #[inline] get_last_cluster(&self, start_cluster: Cluster) -> Option<Cluster>776 pub fn get_last_cluster(&self, start_cluster: Cluster) -> Option<Cluster> { 777 return self.cluster_iter(start_cluster).last(); 778 } 779 780 /// @brief 判断FAT文件系统的shut bit是否正常。 781 /// 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” 782 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 783 /// 784 /// @return Ok(true) 正常 785 /// @return Ok(false) 不正常 786 /// @return Err(SystemError) 在判断时发生错误 787 #[allow(dead_code)] is_shut_bit_ok(&mut self) -> Result<bool, SystemError>788 pub fn is_shut_bit_ok(&mut self) -> Result<bool, SystemError> { 789 match self.bpb.fat_type { 790 FATType::FAT32(_) => { 791 // 对于FAT32, error bit位于第一个扇区的第8字节。 792 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0800_0000; 793 return Ok(bit > 0); 794 } 795 FATType::FAT16(_) => { 796 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x8000; 797 return Ok(bit > 0); 798 } 799 _ => return Ok(true), 800 } 801 } 802 803 /// @brief 判断FAT文件系统的hard error bit是否正常。 804 /// 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 805 /// 卷上的某些扇区可能已损坏。 806 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 807 /// 808 /// @return Ok(true) 正常 809 /// @return Ok(false) 不正常 810 /// @return Err(SystemError) 在判断时发生错误 is_hard_error_bit_ok(&mut self) -> Result<bool, SystemError>811 pub fn is_hard_error_bit_ok(&mut self) -> Result<bool, SystemError> { 812 match self.bpb.fat_type { 813 FATType::FAT32(_) => { 814 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0400_0000; 815 return Ok(bit > 0); 816 } 817 FATType::FAT16(_) => { 818 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x4000; 819 return Ok(bit > 0); 820 } 821 _ => return Ok(true), 822 } 823 } 824 825 /// @brief 设置文件系统的shut bit为正常状态 826 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 827 /// 828 /// @return Ok(()) 设置成功 829 /// @return Err(SystemError) 在设置过程中，出现错误 set_shut_bit_ok(&mut self) -> Result<(), SystemError>830 pub fn set_shut_bit_ok(&mut self) -> Result<(), SystemError> { 831 match self.bpb.fat_type { 832 FATType::FAT32(_) => { 833 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0800_0000; 834 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 835 836 return Ok(()); 837 } 838 839 FATType::FAT16(_) => { 840 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x8000; 841 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 842 return Ok(()); 843 } 844 _ => return Ok(()), 845 } 846 } 847 848 /// @brief 设置文件系统的hard error bit为正常状态 849 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 850 /// 851 /// @return Ok(()) 设置成功 852 /// @return Err(SystemError) 在设置过程中，出现错误 set_hard_error_bit_ok(&mut self) -> Result<(), SystemError>853 pub fn set_hard_error_bit_ok(&mut self) -> Result<(), SystemError> { 854 match self.bpb.fat_type { 855 FATType::FAT32(_) => { 856 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0400_0000; 857 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 858 return Ok(()); 859 } 860 861 FATType::FAT16(_) => { 862 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x4000; 863 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 864 return Ok(()); 865 } 866 _ => return Ok(()), 867 } 868 } 869 870 /// @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 umount(&mut self) -> Result<(), SystemError>871 pub fn umount(&mut self) -> Result<(), SystemError> { 872 self.fs_info.0.lock().flush(&self.partition)?; 873 874 self.set_shut_bit_ok()?; 875 876 self.set_hard_error_bit_ok()?; 877 878 self.partition.disk().sync()?; 879 880 return Ok(()); 881 } 882 883 /// @brief 获取文件系统的最大簇号 max_cluster_number(&self) -> Cluster884 pub fn max_cluster_number(&self) -> Cluster { 885 match self.bpb.fat_type { 886 FATType::FAT32(s) => { 887 // FAT32 888 889 // 数据扇区数量（总扇区数-保留扇区-FAT占用的扇区） 890 let data_sec: u64 = self.bpb.total_sectors_32 as u64 891 - (self.bpb.rsvd_sec_cnt as u64 892 + self.bpb.num_fats as u64 * s.fat_size_32 as u64); 893 894 // 数据区的簇数量 895 let total_clusters: u64 = data_sec / self.bpb.sector_per_cluster as u64; 896 897 // 返回最大的簇号 898 return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); 899 } 900 901 _ => { 902 // FAT12 / FAT16 903 let root_dir_sectors: u64 = (((self.bpb.root_entries_cnt as u64) * 32) 904 + self.bpb.bytes_per_sector as u64 905 - 1) 906 / self.bpb.bytes_per_sector as u64; 907 // 数据区扇区数 908 let data_sec: u64 = self.bpb.total_sectors_16 as u64 909 - (self.bpb.rsvd_sec_cnt as u64 910 + (self.bpb.num_fats as u64 * self.bpb.fat_size_16 as u64) 911 + root_dir_sectors); 912 let total_clusters = data_sec / self.bpb.sector_per_cluster as u64; 913 return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); 914 } 915 } 916 } 917 918 /// @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 919 /// 920 /// @param start_cluster 起始簇号 921 /// @param end_cluster 终止簇号（不包含） 922 /// 923 /// @return Ok(Cluster) 寻找到的空闲簇 924 /// @return Err(SystemError) 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. get_free_cluster( &self, start_cluster: Cluster, end_cluster: Cluster, ) -> Result<Cluster, SystemError>925 pub fn get_free_cluster( 926 &self, 927 start_cluster: Cluster, 928 end_cluster: Cluster, 929 ) -> Result<Cluster, SystemError> { 930 let max_cluster: Cluster = self.max_cluster_number(); 931 let mut cluster: u64 = start_cluster.cluster_num; 932 933 let fat_type: FATType = self.bpb.fat_type; 934 let fat_start_sector: u64 = self.fat_start_sector(); 935 let bytes_per_sec: u64 = self.bpb.bytes_per_sector as u64; 936 937 match fat_type { 938 FATType::FAT12(_) => { 939 let part_bytes_offset: u64 = 940 fat_type.get_fat_bytes_offset(start_cluster, fat_start_sector, bytes_per_sec); 941 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 942 943 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 944 945 // 由于FAT12的FAT表不大于6K，因此直接读取6K 946 let num_lba = (6 * 1024) / LBA_SIZE; 947 let mut v: Vec<u8> = Vec::new(); 948 v.resize(num_lba * LBA_SIZE, 0); 949 self.partition.disk().read_at(lba, num_lba, &mut v)?; 950 951 let mut cursor: VecCursor = VecCursor::new(v); 952 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 953 954 let mut packed_val: u16 = cursor.read_u16()?; 955 loop { 956 let val = if (cluster & 0x1) > 0 { 957 packed_val >> 4 958 } else { 959 packed_val & 0x0fff 960 }; 961 if val == 0 { 962 return Ok(Cluster::new(cluster as u64)); 963 } 964 965 cluster += 1; 966 967 // 磁盘无剩余空间，或者簇号达到给定的最大值 968 if cluster == end_cluster.cluster_num || cluster == max_cluster.cluster_num { 969 return Err(SystemError::ENOSPC); 970 } 971 972 packed_val = match cluster & 1 { 973 0 => cursor.read_u16()?, 974 _ => { 975 let next_byte = cursor.read_u8()? as u16; 976 (packed_val >> 8) | (next_byte << 8) 977 } 978 }; 979 } 980 } 981 FATType::FAT16(_) => { 982 // todo: 优化这里，减少读取磁盘的次数。 983 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { 984 let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( 985 Cluster::new(cluster), 986 fat_start_sector, 987 bytes_per_sec, 988 ); 989 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 990 991 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 992 993 let mut v: Vec<u8> = Vec::new(); 994 v.resize(self.lba_per_sector() * LBA_SIZE, 0); 995 self.partition 996 .disk() 997 .read_at(lba, self.lba_per_sector(), &mut v)?; 998 999 let mut cursor: VecCursor = VecCursor::new(v); 1000 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1001 1002 let val = cursor.read_u16()?; 1003 // 找到空闲簇 1004 if val == 0 { 1005 return Ok(Cluster::new(val as u64)); 1006 } 1007 cluster += 1; 1008 } 1009 1010 // 磁盘无剩余空间，或者簇号达到给定的最大值 1011 return Err(SystemError::ENOSPC); 1012 } 1013 FATType::FAT32(_) => { 1014 // todo: 优化这里，减少读取磁盘的次数。 1015 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { 1016 let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( 1017 Cluster::new(cluster), 1018 fat_start_sector, 1019 bytes_per_sec, 1020 ); 1021 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 1022 1023 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 1024 1025 let mut v: Vec<u8> = Vec::new(); 1026 v.resize(self.lba_per_sector() * LBA_SIZE, 0); 1027 self.partition 1028 .disk() 1029 .read_at(lba, self.lba_per_sector(), &mut v)?; 1030 1031 let mut cursor: VecCursor = VecCursor::new(v); 1032 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1033 1034 let val = cursor.read_u32()? & 0x0fffffff; 1035 1036 if val == 0 { 1037 return Ok(Cluster::new(cluster)); 1038 } 1039 cluster += 1; 1040 } 1041 1042 // 磁盘无剩余空间，或者簇号达到给定的最大值 1043 return Err(SystemError::ENOSPC); 1044 } 1045 } 1046 } 1047 1048 /// @brief 在FAT表中，设置指定的簇的信息。 1049 /// 1050 /// @param cluster 目标簇 1051 /// @param fat_entry 这个簇在FAT表中，存储的信息（下一个簇的簇号） set_entry(&self, cluster: Cluster, fat_entry: FATEntry) -> Result<(), SystemError>1052 pub fn set_entry(&self, cluster: Cluster, fat_entry: FATEntry) -> Result<(), SystemError> { 1053 // fat表项在分区上的字节偏移量 1054 let fat_part_bytes_offset: u64 = self.bpb.fat_type.get_fat_bytes_offset( 1055 cluster, 1056 self.fat_start_sector(), 1057 self.bpb.bytes_per_sector as u64, 1058 ); 1059 1060 match self.bpb.fat_type { 1061 FATType::FAT12(_) => { 1062 // 计算要写入的值 1063 let raw_val: u16 = match fat_entry { 1064 FATEntry::Unused => 0, 1065 FATEntry::Bad => 0xff7, 1066 FATEntry::EndOfChain => 0xfff, 1067 FATEntry::Next(c) => c.cluster_num as u16, 1068 }; 1069 1070 let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); 1071 1072 let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); 1073 1074 let mut v: Vec<u8> = Vec::new(); 1075 v.resize(LBA_SIZE, 0); 1076 self.partition.disk().read_at(lba, 1, &mut v)?; 1077 1078 let mut cursor: VecCursor = VecCursor::new(v); 1079 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1080 1081 let old_val: u16 = cursor.read_u16()?; 1082 let new_val: u16 = if (cluster.cluster_num & 0x1) > 0 { 1083 (old_val & 0x000f) | (raw_val << 4) 1084 } else { 1085 (old_val & 0xf000) | raw_val 1086 }; 1087 1088 // 写回数据到磁盘上 1089 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1090 cursor.write_u16(new_val)?; 1091 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1092 return Ok(()); 1093 } 1094 FATType::FAT16(_) => { 1095 // 计算要写入的值 1096 let raw_val: u16 = match fat_entry { 1097 FATEntry::Unused => 0, 1098 FATEntry::Bad => 0xfff7, 1099 FATEntry::EndOfChain => 0xfdff, 1100 FATEntry::Next(c) => c.cluster_num as u16, 1101 }; 1102 1103 let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); 1104 1105 let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); 1106 1107 let mut v: Vec<u8> = Vec::new(); 1108 v.resize(LBA_SIZE, 0); 1109 self.partition.disk().read_at(lba, 1, &mut v)?; 1110 1111 let mut cursor: VecCursor = VecCursor::new(v); 1112 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1113 1114 cursor.write_u16(raw_val)?; 1115 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1116 1117 return Ok(()); 1118 } 1119 FATType::FAT32(_) => { 1120 let fat_size: u64 = self.fat_size(); 1121 let bound: u64 = if self.mirroring_enabled() { 1122 1 1123 } else { 1124 self.bpb.num_fats as u64 1125 }; 1126 // kdebug!("set entry, bound={bound}, fat_size={fat_size}"); 1127 for i in 0..bound { 1128 // 当前操作的FAT表在磁盘上的字节偏移量 1129 let f_offset: u64 = fat_part_bytes_offset + i * fat_size; 1130 let in_block_offset: u64 = self.get_in_block_offset(f_offset); 1131 let lba = self.get_lba_from_offset(self.bytes_to_sector(f_offset)); 1132 1133 // kdebug!("set entry, lba={lba}, in_block_offset={in_block_offset}"); 1134 let mut v: Vec<u8> = Vec::new(); 1135 v.resize(LBA_SIZE, 0); 1136 self.partition.disk().read_at(lba, 1, &mut v)?; 1137 1138 let mut cursor: VecCursor = VecCursor::new(v); 1139 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1140 1141 // FAT32的高4位保留 1142 let old_bits = cursor.read_u32()? & 0xf0000000; 1143 1144 if fat_entry == FATEntry::Unused 1145 && cluster.cluster_num >= 0x0ffffff7 1146 && cluster.cluster_num <= 0x0fffffff 1147 { 1148 kerror!( 1149 "FAT32: Reserved Cluster {:?} cannot be marked as free", 1150 cluster 1151 ); 1152 return Err(SystemError::EPERM); 1153 } 1154 1155 // 计算要写入的值 1156 let mut raw_val: u32 = match fat_entry { 1157 FATEntry::Unused => 0, 1158 FATEntry::Bad => 0x0FFFFFF7, 1159 FATEntry::EndOfChain => 0x0FFFFFFF, 1160 FATEntry::Next(c) => c.cluster_num as u32, 1161 }; 1162 1163 // 恢复保留位 1164 raw_val |= old_bits; 1165 1166 // kdebug!("sent entry, raw_val={raw_val}"); 1167 1168 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1169 cursor.write_u32(raw_val)?; 1170 1171 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1172 } 1173 1174 return Ok(()); 1175 } 1176 } 1177 } 1178 1179 /// @brief 清空指定的簇 1180 /// 1181 /// @param cluster 要被清空的簇 zero_cluster(&self, cluster: Cluster) -> Result<(), SystemError>1182 pub fn zero_cluster(&self, cluster: Cluster) -> Result<(), SystemError> { 1183 // 准备数据，用于写入 1184 let zeros: Vec<u8> = vec![0u8; self.bytes_per_cluster() as usize]; 1185 let offset: usize = self.cluster_bytes_offset(cluster) as usize; 1186 self.partition 1187 .disk() 1188 .write_at_bytes(offset, zeros.len(), zeros.as_slice())?; 1189 return Ok(()); 1190 } 1191 } 1192 1193 impl Drop for FATFileSystem { drop(&mut self)1194 fn drop(&mut self) { 1195 let r = self.umount(); 1196 if r.is_err() { 1197 kerror!( 1198 "Umount FAT filesystem failed: errno={:?}, FS detail:{self:?}", 1199 r.as_ref().unwrap_err() 1200 ); 1201 } 1202 } 1203 } 1204 1205 impl FATFsInfo { 1206 const LEAD_SIG: u32 = 0x41615252; 1207 const STRUC_SIG: u32 = 0x61417272; 1208 const TRAIL_SIG: u32 = 0xAA550000; 1209 #[allow(dead_code)] 1210 const FS_INFO_SIZE: u64 = 512; 1211 1212 /// @brief 从磁盘上读取FAT文件系统的FSInfo结构体 1213 /// 1214 /// @param partition 磁盘分区 1215 /// @param in_disk_fs_info_offset FSInfo扇区在磁盘内的字节偏移量（单位：字节） 1216 /// @param bytes_per_sec 每扇区字节数 new( partition: Arc<Partition>, in_disk_fs_info_offset: u64, bytes_per_sec: usize, ) -> Result<Self, SystemError>1217 pub fn new( 1218 partition: Arc<Partition>, 1219 in_disk_fs_info_offset: u64, 1220 bytes_per_sec: usize, 1221 ) -> Result<Self, SystemError> { 1222 let mut v = Vec::<u8>::new(); 1223 v.resize(bytes_per_sec, 0); 1224 1225 // 计算fs_info扇区在磁盘上的字节偏移量，从磁盘读取数据 1226 partition 1227 .disk() 1228 .read_at(in_disk_fs_info_offset as usize / LBA_SIZE, 1, &mut v)?; 1229 let mut cursor = VecCursor::new(v); 1230 1231 let mut fsinfo = FATFsInfo::default(); 1232 1233 fsinfo.lead_sig = cursor.read_u32()?; 1234 cursor.seek(SeekFrom::SeekCurrent(480))?; 1235 fsinfo.struc_sig = cursor.read_u32()?; 1236 fsinfo.free_count = cursor.read_u32()?; 1237 fsinfo.next_free = cursor.read_u32()?; 1238 1239 cursor.seek(SeekFrom::SeekCurrent(12))?; 1240 1241 fsinfo.trail_sig = cursor.read_u32()?; 1242 fsinfo.dirty = false; 1243 fsinfo.offset = Some(in_disk_fs_info_offset); 1244 1245 if fsinfo.is_valid() { 1246 return Ok(fsinfo); 1247 } else { 1248 kerror!("Error occurred while parsing FATFsInfo."); 1249 return Err(SystemError::EINVAL); 1250 } 1251 } 1252 1253 /// @brief 判断是否为正确的FsInfo结构体 is_valid(&self) -> bool1254 fn is_valid(&self) -> bool { 1255 self.lead_sig == Self::LEAD_SIG 1256 && self.struc_sig == Self::STRUC_SIG 1257 && self.trail_sig == Self::TRAIL_SIG 1258 } 1259 1260 /// @brief 根据fsinfo的信息，计算当前总的空闲簇数量 1261 /// 1262 /// @param 当前文件系统的最大簇号 count_free_cluster(&self, max_cluster: Cluster) -> Option<u64>1263 pub fn count_free_cluster(&self, max_cluster: Cluster) -> Option<u64> { 1264 let count_clusters = max_cluster.cluster_num - RESERVED_CLUSTERS as u64 + 1; 1265 // 信息不合理，当前的FsInfo中存储的free count大于计算出来的值 1266 if self.free_count as u64 > count_clusters { 1267 return None; 1268 } else { 1269 match self.free_count { 1270 // free count字段不可用 1271 0xffffffff => return None, 1272 // 返回FsInfo中存储的数据 1273 n => return Some(n as u64), 1274 } 1275 } 1276 } 1277 1278 /// @brief 更新FsInfo中的“空闲簇统计信息“为new_count 1279 /// 1280 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 update_free_count_abs(&mut self, new_count: u32)1281 pub fn update_free_count_abs(&mut self, new_count: u32) { 1282 self.free_count = new_count; 1283 } 1284 1285 /// @brief 更新FsInfo中的“空闲簇统计信息“，把它加上delta. 1286 /// 1287 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 update_free_count_delta(&mut self, delta: i32)1288 pub fn update_free_count_delta(&mut self, delta: i32) { 1289 self.free_count = (self.free_count as i32 + delta) as u32; 1290 } 1291 1292 /// @brief 更新FsInfo中的“第一个空闲簇统计信息“为next_free. 1293 /// 1294 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 update_next_free(&mut self, next_free: u32)1295 pub fn update_next_free(&mut self, next_free: u32) { 1296 // 这个值是参考量，不一定要准确，仅供加速查找 1297 self.next_free = next_free; 1298 } 1299 1300 /// @brief 获取fs info 记载的第一个空闲簇。（不一定准确，仅供参考） next_free(&self) -> Option<u64>1301 pub fn next_free(&self) -> Option<u64> { 1302 match self.next_free { 1303 0xffffffff => return None, 1304 0 | 1 => return None, 1305 n => return Some(n as u64), 1306 }; 1307 } 1308 1309 /// @brief 把fs info刷入磁盘 1310 /// 1311 /// @param partition fs info所在的分区 flush(&self, partition: &Arc<Partition>) -> Result<(), SystemError>1312 pub fn flush(&self, partition: &Arc<Partition>) -> Result<(), SystemError> { 1313 if let Some(off) = self.offset { 1314 let in_block_offset = off % LBA_SIZE as u64; 1315 1316 let lba = off as usize / LBA_SIZE; 1317 1318 let mut v: Vec<u8> = Vec::new(); 1319 v.resize(LBA_SIZE, 0); 1320 partition.disk().read_at(lba, 1, &mut v)?; 1321 1322 let mut cursor: VecCursor = VecCursor::new(v); 1323 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1324 1325 cursor.write_u32(self.lead_sig)?; 1326 cursor.seek(SeekFrom::SeekCurrent(480))?; 1327 cursor.write_u32(self.struc_sig)?; 1328 cursor.write_u32(self.free_count)?; 1329 cursor.write_u32(self.next_free)?; 1330 cursor.seek(SeekFrom::SeekCurrent(12))?; 1331 cursor.write_u32(self.trail_sig)?; 1332 1333 partition.disk().write_at(lba, 1, cursor.as_slice())?; 1334 } 1335 return Ok(()); 1336 } 1337 1338 /// @brief 读取磁盘上的Fs Info扇区，将里面的内容更新到结构体中 1339 /// 1340 /// @param partition fs info所在的分区 update(&mut self, partition: Arc<Partition>) -> Result<(), SystemError>1341 pub fn update(&mut self, partition: Arc<Partition>) -> Result<(), SystemError> { 1342 if let Some(off) = self.offset { 1343 let in_block_offset = off % LBA_SIZE as u64; 1344 1345 let lba = off as usize / LBA_SIZE; 1346 1347 let mut v: Vec<u8> = Vec::new(); 1348 v.resize(LBA_SIZE, 0); 1349 partition.disk().read_at(lba, 1, &mut v)?; 1350 let mut cursor: VecCursor = VecCursor::new(v); 1351 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1352 self.lead_sig = cursor.read_u32()?; 1353 1354 cursor.seek(SeekFrom::SeekCurrent(480))?; 1355 self.struc_sig = cursor.read_u32()?; 1356 self.free_count = cursor.read_u32()?; 1357 self.next_free = cursor.read_u32()?; 1358 cursor.seek(SeekFrom::SeekCurrent(12))?; 1359 self.trail_sig = cursor.read_u32()?; 1360 } 1361 return Ok(()); 1362 } 1363 } 1364 1365 impl IndexNode for LockedFATInode { read_at( &self, offset: usize, len: usize, buf: &mut [u8], _data: &mut FilePrivateData, ) -> Result<usize, SystemError>1366 fn read_at( 1367 &self, 1368 offset: usize, 1369 len: usize, 1370 buf: &mut [u8], 1371 _data: &mut FilePrivateData, 1372 ) -> Result<usize, SystemError> { 1373 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1374 match &guard.inode_type { 1375 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 1376 let r = f.read( 1377 &guard.fs.upgrade().unwrap(), 1378 &mut buf[0..len], 1379 offset as u64, 1380 ); 1381 guard.update_metadata(); 1382 return r; 1383 } 1384 FATDirEntry::Dir(_) => { 1385 return Err(SystemError::EISDIR); 1386 } 1387 FATDirEntry::UnInit => { 1388 kerror!("FATFS: param: Inode_type uninitialized."); 1389 return Err(SystemError::EROFS); 1390 } 1391 } 1392 } 1393 write_at( &self, offset: usize, len: usize, buf: &[u8], _data: &mut FilePrivateData, ) -> Result<usize, SystemError>1394 fn write_at( 1395 &self, 1396 offset: usize, 1397 len: usize, 1398 buf: &[u8], 1399 _data: &mut FilePrivateData, 1400 ) -> Result<usize, SystemError> { 1401 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1402 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1403 1404 match &mut guard.inode_type { 1405 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 1406 let r = f.write(fs, &buf[0..len], offset as u64); 1407 guard.update_metadata(); 1408 return r; 1409 } 1410 FATDirEntry::Dir(_) => { 1411 return Err(SystemError::EISDIR); 1412 } 1413 FATDirEntry::UnInit => { 1414 kerror!("FATFS: param: Inode_type uninitialized."); 1415 return Err(SystemError::EROFS); 1416 } 1417 } 1418 } 1419 create( &self, name: &str, file_type: FileType, _mode: ModeType, ) -> Result<Arc<dyn IndexNode>, SystemError>1420 fn create( 1421 &self, 1422 name: &str, 1423 file_type: FileType, 1424 _mode: ModeType, 1425 ) -> Result<Arc<dyn IndexNode>, SystemError> { 1426 // 由于FAT32不支持文件权限的功能，因此忽略mode参数 1427 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1428 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1429 1430 match &mut guard.inode_type { 1431 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1432 return Err(SystemError::ENOTDIR); 1433 } 1434 FATDirEntry::Dir(d) => match file_type { 1435 FileType::File => { 1436 d.create_file(name, fs)?; 1437 return Ok(guard.find(name)?); 1438 } 1439 FileType::Dir => { 1440 d.create_dir(name, fs)?; 1441 return Ok(guard.find(name)?); 1442 } 1443 1444 FileType::SymLink => return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP), 1445 _ => return Err(SystemError::EINVAL), 1446 }, 1447 FATDirEntry::UnInit => { 1448 kerror!("FATFS: param: Inode_type uninitialized."); 1449 return Err(SystemError::EROFS); 1450 } 1451 } 1452 } 1453 fs(&self) -> Arc<dyn FileSystem>1454 fn fs(&self) -> Arc<dyn FileSystem> { 1455 return self.0.lock().fs.upgrade().unwrap(); 1456 } 1457 as_any_ref(&self) -> &dyn core::any::Any1458 fn as_any_ref(&self) -> &dyn core::any::Any { 1459 return self; 1460 } 1461 metadata(&self) -> Result<Metadata, SystemError>1462 fn metadata(&self) -> Result<Metadata, SystemError> { 1463 return Ok(self.0.lock().metadata.clone()); 1464 } resize(&self, len: usize) -> Result<(), SystemError>1465 fn resize(&self, len: usize) -> Result<(), SystemError> { 1466 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1467 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1468 let old_size = guard.metadata.size as usize; 1469 1470 match &mut guard.inode_type { 1471 FATDirEntry::File(file) | FATDirEntry::VolId(file) => { 1472 // 如果新的长度和旧的长度相同，那么就直接返回 1473 if len == old_size { 1474 return Ok(()); 1475 } else if len > old_size { 1476 // 如果新的长度比旧的长度大，那么就在文件末尾添加空白 1477 let mut buf: Vec<u8> = Vec::new(); 1478 let mut remain_size = len - old_size; 1479 let buf_size = remain_size; 1480 // let buf_size = core::cmp::min(remain_size, 512 * 1024); 1481 buf.resize(buf_size, 0); 1482 1483 let mut offset = old_size; 1484 while remain_size > 0 { 1485 let write_size = core::cmp::min(remain_size, buf_size); 1486 file.write(fs, &buf[0..write_size], offset as u64)?; 1487 remain_size -= write_size; 1488 offset += write_size; 1489 } 1490 } else { 1491 file.truncate(fs, len as u64)?; 1492 } 1493 guard.update_metadata(); 1494 return Ok(()); 1495 } 1496 FATDirEntry::Dir(_) => return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP), 1497 FATDirEntry::UnInit => { 1498 kerror!("FATFS: param: Inode_type uninitialized."); 1499 return Err(SystemError::EROFS); 1500 } 1501 } 1502 } 1503 truncate(&self, len: usize) -> Result<(), SystemError>1504 fn truncate(&self, len: usize) -> Result<(), SystemError> { 1505 let guard: SpinLockGuard<FATInode> = self.0.lock(); 1506 let old_size = guard.metadata.size as usize; 1507 if len < old_size { 1508 drop(guard); 1509 self.resize(len) 1510 } else { 1511 Ok(()) 1512 } 1513 } 1514 list(&self) -> Result<Vec<String>, SystemError>1515 fn list(&self) -> Result<Vec<String>, SystemError> { 1516 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1517 let fatent: &FATDirEntry = &guard.inode_type; 1518 match fatent { 1519 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1520 return Err(SystemError::ENOTDIR); 1521 } 1522 FATDirEntry::Dir(dir) => { 1523 // 获取当前目录下的所有目录项 1524 let mut ret: Vec<String> = Vec::new(); 1525 let dir_iter: FATDirIter = dir.to_iter(guard.fs.upgrade().unwrap()); 1526 for ent in dir_iter { 1527 ret.push(ent.name()); 1528 1529 // ====== 生成inode缓存，存入B树 1530 let name: String = ent.name(); 1531 // kdebug!("name={name}"); 1532 1533 if guard.children.contains_key(&name.to_uppercase()) == false 1534 && name != "." 1535 && name != ".." 1536 { 1537 // 创建新的inode 1538 let entry_inode: Arc<LockedFATInode> = LockedFATInode::new( 1539 guard.fs.upgrade().unwrap(), 1540 guard.self_ref.clone(), 1541 ent, 1542 ); 1543 // 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 1544 guard 1545 .children 1546 .insert(name.to_uppercase(), entry_inode.clone()); 1547 } 1548 } 1549 return Ok(ret); 1550 } 1551 FATDirEntry::UnInit => { 1552 kerror!("FATFS: param: Inode_type uninitialized."); 1553 return Err(SystemError::EROFS); 1554 } 1555 } 1556 } 1557 find(&self, name: &str) -> Result<Arc<dyn IndexNode>, SystemError>1558 fn find(&self, name: &str) -> Result<Arc<dyn IndexNode>, SystemError> { 1559 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1560 let target = guard.find(name)?; 1561 return Ok(target); 1562 } 1563 open(&self, _data: &mut FilePrivateData, _mode: &FileMode) -> Result<(), SystemError>1564 fn open(&self, _data: &mut FilePrivateData, _mode: &FileMode) -> Result<(), SystemError> { 1565 return Ok(()); 1566 } 1567 close(&self, _data: &mut FilePrivateData) -> Result<(), SystemError>1568 fn close(&self, _data: &mut FilePrivateData) -> Result<(), SystemError> { 1569 return Ok(()); 1570 } 1571 unlink(&self, name: &str) -> Result<(), SystemError>1572 fn unlink(&self, name: &str) -> Result<(), SystemError> { 1573 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1574 let target: Arc<LockedFATInode> = guard.find(name)?; 1575 // 对目标inode上锁，以防更改 1576 let target_guard: SpinLockGuard<FATInode> = target.0.lock(); 1577 // 先从缓存删除 1578 let nod = guard.children.remove(&name.to_uppercase()); 1579 1580 // 若删除缓存中为管道的文件，则不需要再到磁盘删除 1581 if let Some(_) = nod { 1582 let file_type = target_guard.metadata.file_type; 1583 if file_type == FileType::Pipe { 1584 return Ok(()); 1585 } 1586 } 1587 1588 let dir = match &guard.inode_type { 1589 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1590 return Err(SystemError::ENOTDIR); 1591 } 1592 FATDirEntry::Dir(d) => d, 1593 FATDirEntry::UnInit => { 1594 kerror!("FATFS: param: Inode_type uninitialized."); 1595 return Err(SystemError::EROFS); 1596 } 1597 }; 1598 // 检查文件是否存在 1599 dir.check_existence(name, Some(false), guard.fs.upgrade().unwrap())?; 1600 1601 // 再从磁盘删除 1602 let r = dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); 1603 drop(target_guard); 1604 return r; 1605 } 1606 rmdir(&self, name: &str) -> Result<(), SystemError>1607 fn rmdir(&self, name: &str) -> Result<(), SystemError> { 1608 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1609 let target: Arc<LockedFATInode> = guard.find(name)?; 1610 // 对目标inode上锁，以防更改 1611 let target_guard: SpinLockGuard<FATInode> = target.0.lock(); 1612 // 先从缓存删除 1613 guard.children.remove(&name.to_uppercase()); 1614 1615 let dir = match &guard.inode_type { 1616 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1617 return Err(SystemError::ENOTDIR); 1618 } 1619 FATDirEntry::Dir(d) => d, 1620 FATDirEntry::UnInit => { 1621 kerror!("FATFS: param: Inode_type uninitialized."); 1622 return Err(SystemError::EROFS); 1623 } 1624 }; 1625 // 检查文件夹是否存在 1626 dir.check_existence(name, Some(true), guard.fs.upgrade().unwrap())?; 1627 1628 // 再从磁盘删除 1629 let r: Result<(), SystemError> = 1630 dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); 1631 if r.is_ok() { 1632 return r; 1633 } else { 1634 let r = r.unwrap_err(); 1635 if r == SystemError::ENOTEMPTY { 1636 // 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 1637 guard.children.insert(name.to_uppercase(), target.clone()); 1638 drop(target_guard); 1639 } 1640 return Err(r); 1641 } 1642 } 1643 get_entry_name(&self, ino: InodeId) -> Result<String, SystemError>1644 fn get_entry_name(&self, ino: InodeId) -> Result<String, SystemError> { 1645 let guard: SpinLockGuard<FATInode> = self.0.lock(); 1646 if guard.metadata.file_type != FileType::Dir { 1647 return Err(SystemError::ENOTDIR); 1648 } 1649 match ino.into() { 1650 0 => { 1651 return Ok(String::from(".")); 1652 } 1653 1 => { 1654 return Ok(String::from("..")); 1655 } 1656 ino => { 1657 // 暴力遍历所有的children，判断inode id是否相同 1658 // TODO: 优化这里，这个地方性能很差！ 1659 let mut key: Vec<String> = guard 1660 .children 1661 .keys() 1662 .filter(|k| { 1663 guard 1664 .children 1665 .get(*k) 1666 .unwrap() 1667 .metadata() 1668 .unwrap() 1669 .inode_id 1670 .into() 1671 == ino 1672 }) 1673 .cloned() 1674 .collect(); 1675 1676 match key.len() { 1677 0=>{return Err(SystemError::ENOENT);} 1678 1=>{return Ok(key.remove(0));} 1679 _ => 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) 1680 } 1681 } 1682 } 1683 } 1684 mknod( &self, filename: &str, mode: ModeType, _dev_t: DeviceNumber, ) -> Result<Arc<dyn IndexNode>, SystemError>1685 fn mknod( 1686 &self, 1687 filename: &str, 1688 mode: ModeType, 1689 _dev_t: DeviceNumber, 1690 ) -> Result<Arc<dyn IndexNode>, SystemError> { 1691 let mut inode = self.0.lock(); 1692 if inode.metadata.file_type != FileType::Dir { 1693 return Err(SystemError::ENOTDIR); 1694 } 1695 1696 // 判断需要创建的类型 1697 if unlikely(mode.contains(ModeType::S_IFREG)) { 1698 // 普通文件 1699 return Ok(self.create(filename, FileType::File, mode)?); 1700 } 1701 1702 let nod = LockedFATInode::new( 1703 inode.fs.upgrade().unwrap(), 1704 inode.self_ref.clone(), 1705 FATDirEntry::File(FATFile::default()), 1706 ); 1707 1708 if mode.contains(ModeType::S_IFIFO) { 1709 nod.0.lock().metadata.file_type = FileType::Pipe; 1710 // 创建pipe文件 1711 let pipe_inode = LockedPipeInode::new(); 1712 // 设置special_node 1713 nod.0.lock().special_node = Some(SpecialNodeData::Pipe(pipe_inode)); 1714 } else if mode.contains(ModeType::S_IFBLK) { 1715 nod.0.lock().metadata.file_type = FileType::BlockDevice; 1716 unimplemented!() 1717 } else if mode.contains(ModeType::S_IFCHR) { 1718 nod.0.lock().metadata.file_type = FileType::CharDevice; 1719 unimplemented!() 1720 } else { 1721 return Err(SystemError::EINVAL); 1722 } 1723 1724 inode 1725 .children 1726 .insert(String::from(filename).to_uppercase(), nod.clone()); 1727 Ok(nod) 1728 } 1729 special_node(&self) -> Option<SpecialNodeData>1730 fn special_node(&self) -> Option<SpecialNodeData> { 1731 self.0.lock().special_node.clone() 1732 } 1733 } 1734 1735 impl Default for FATFsInfo { default() -> Self1736 fn default() -> Self { 1737 return FATFsInfo { 1738 lead_sig: FATFsInfo::LEAD_SIG, 1739 struc_sig: FATFsInfo::STRUC_SIG, 1740 free_count: 0xFFFFFFFF, 1741 next_free: RESERVED_CLUSTERS, 1742 trail_sig: FATFsInfo::TRAIL_SIG, 1743 dirty: false, 1744 offset: None, 1745 }; 1746 } 1747 } 1748 1749 impl Cluster { new(cluster: u64) -> Self1750 pub fn new(cluster: u64) -> Self { 1751 return Cluster { 1752 cluster_num: cluster, 1753 parent_cluster: 0, 1754 }; 1755 } 1756 } 1757 1758 /// @brief 用于迭代FAT表的内容的簇迭代器对象 1759 #[derive(Debug)] 1760 struct ClusterIter<'a> { 1761 /// 迭代器的next要返回的簇 1762 current_cluster: Option<Cluster>, 1763 /// 属于的文件系统 1764 fs: &'a FATFileSystem, 1765 } 1766 1767 impl<'a> Iterator for ClusterIter<'a> { 1768 type Item = Cluster; 1769 next(&mut self) -> Option<Self::Item>1770 fn next(&mut self) -> Option<Self::Item> { 1771 // 当前要返回的簇 1772 let ret: Option<Cluster> = self.current_cluster; 1773 1774 // 获得下一个要返回簇 1775 let new: Option<Cluster> = match self.current_cluster { 1776 Some(c) => { 1777 let entry: Option<FATEntry> = self.fs.get_fat_entry(c).ok(); 1778 match entry { 1779 Some(FATEntry::Next(c)) => Some(c), 1780 _ => None, 1781 } 1782 } 1783 _ => None, 1784 }; 1785 1786 self.current_cluster = new; 1787 return ret; 1788 } 1789 } 1790