1 #![allow(dead_code)] 2 use core::{any::Any, fmt::Debug}; 3 4 use alloc::{ 5 collections::BTreeMap, 6 string::String, 7 sync::{Arc, Weak}, 8 vec::Vec, 9 }; 10 11 use crate::{ 12 filesystem::vfs::io::{device::LBA_SIZE, disk_info::Partition, SeekFrom}, 13 filesystem::vfs::{ 14 core::generate_inode_id, 15 file::{FileMode, FilePrivateData}, 16 FileSystem, FileType, IndexNode, InodeId, Metadata, PollStatus, 17 }, 18 kerror, 19 libs::{ 20 spinlock::{SpinLock, SpinLockGuard}, 21 vec_cursor::VecCursor, 22 }, 23 syscall::SystemError, 24 time::TimeSpec, 25 }; 26 27 use super::{ 28 bpb::{BiosParameterBlock, FATType}, 29 entry::{FATDir, FATDirEntry, FATDirIter, FATEntry}, 30 utils::RESERVED_CLUSTERS, 31 }; 32 33 /// FAT32文件系统的最大的文件大小 34 pub const MAX_FILE_SIZE: u64 = 0xffff_ffff; 35 36 /// @brief 表示当前簇和上一个簇的关系的结构体 37 /// 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。 38 #[derive(Debug, Clone, Copy, Default)] 39 pub struct Cluster { 40 pub cluster_num: u64, 41 pub parent_cluster: u64, 42 } 43 44 impl PartialOrd for Cluster { 45 /// @brief 根据当前簇号比较大小 46 fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> { 47 return self.cluster_num.partial_cmp(&other.cluster_num); 48 } 49 } 50 51 impl PartialEq for Cluster { 52 /// @brief 根据当前簇号比较是否相等 53 fn eq(&self, other: &Self) -> bool { 54 self.cluster_num == other.cluster_num 55 } 56 } 57 58 impl Eq for Cluster {} 59 60 #[derive(Debug)] 61 pub struct FATFileSystem { 62 /// 当前文件系统所在的分区 63 pub partition: Arc<Partition>, 64 /// 当前文件系统的BOPB 65 pub bpb: BiosParameterBlock, 66 /// 当前文件系统的第一个数据扇区（相对分区开始位置） 67 pub first_data_sector: u64, 68 /// 文件系统信息结构体 69 pub fs_info: Arc<LockedFATFsInfo>, 70 /// 文件系统的根inode 71 root_inode: Arc<LockedFATInode>, 72 } 73 74 /// FAT文件系统的Inode 75 #[derive(Debug)] 76 pub struct LockedFATInode(SpinLock<FATInode>); 77 78 #[derive(Debug)] 79 pub struct LockedFATFsInfo(SpinLock<FATFsInfo>); 80 81 impl LockedFATFsInfo { 82 #[inline] 83 pub fn new(fs_info: FATFsInfo) -> Self { 84 return Self(SpinLock::new(fs_info)); 85 } 86 } 87 88 #[derive(Debug)] 89 pub struct FATInode { 90 /// 指向父Inode的弱引用 91 parent: Weak<LockedFATInode>, 92 /// 指向自身的弱引用 93 self_ref: Weak<LockedFATInode>, 94 /// 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。 95 /// 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。 96 children: BTreeMap<String, Arc<LockedFATInode>>, 97 /// 当前inode的元数据 98 metadata: Metadata, 99 /// 指向inode所在的文件系统对象的指针 100 fs: Weak<FATFileSystem>, 101 102 /// 根据不同的Inode类型，创建不同的私有字段 103 inode_type: FATDirEntry, 104 } 105 106 impl FATInode { 107 /// @brief 更新当前inode的元数据 108 pub fn update_metadata(&mut self) { 109 // todo: 更新文件的访问时间等信息 110 match &self.inode_type { 111 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 112 self.metadata.size = f.size() as i64; 113 } 114 FATDirEntry::Dir(d) => { 115 self.metadata.size = d.size(&self.fs.upgrade().unwrap().clone()) as i64; 116 } 117 FATDirEntry::UnInit => { 118 kerror!("update_metadata: Uninitialized FATDirEntry: {:?}", self); 119 return; 120 } 121 }; 122 } 123 124 fn find(&mut self, name: &str) -> Result<Arc<LockedFATInode>, SystemError> { 125 match &self.inode_type { 126 FATDirEntry::Dir(d) => { 127 // 尝试在缓存区查找 128 if let Some(entry) = self.children.get(&name.to_uppercase()) { 129 return Ok(entry.clone()); 130 } 131 // 在缓存区找不到 132 // 在磁盘查找 133 let fat_entry: FATDirEntry = 134 d.find_entry(name, None, None, self.fs.upgrade().unwrap())?; 135 // kdebug!("find entry from disk ok, entry={fat_entry:?}"); 136 // 创建新的inode 137 let entry_inode: Arc<LockedFATInode> = LockedFATInode::new( 138 self.fs.upgrade().unwrap(), 139 self.self_ref.clone(), 140 fat_entry, 141 ); 142 // 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 143 self.children 144 .insert(name.to_uppercase(), entry_inode.clone()); 145 return Ok(entry_inode); 146 } 147 FATDirEntry::UnInit => { 148 panic!( 149 "Uninitialized FAT Inode, fs = {:?}, inode={self:?}", 150 self.fs 151 ) 152 } 153 _ => { 154 return Err(SystemError::ENOTDIR); 155 } 156 } 157 } 158 } 159 160 impl LockedFATInode { 161 pub fn new( 162 fs: Arc<FATFileSystem>, 163 parent: Weak<LockedFATInode>, 164 inode_type: FATDirEntry, 165 ) -> Arc<LockedFATInode> { 166 let file_type = if let FATDirEntry::Dir(_) = inode_type { 167 FileType::Dir 168 } else { 169 FileType::File 170 }; 171 172 let inode: Arc<LockedFATInode> = Arc::new(LockedFATInode(SpinLock::new(FATInode { 173 parent: parent, 174 self_ref: Weak::default(), 175 children: BTreeMap::new(), 176 fs: Arc::downgrade(&fs), 177 inode_type: inode_type, 178 metadata: Metadata { 179 dev_id: 0, 180 inode_id: generate_inode_id(), 181 size: 0, 182 blk_size: fs.bpb.bytes_per_sector as usize, 183 blocks: if let FATType::FAT32(_) = fs.bpb.fat_type { 184 fs.bpb.total_sectors_32 as usize 185 } else { 186 fs.bpb.total_sectors_16 as usize 187 }, 188 atime: TimeSpec::default(), 189 mtime: TimeSpec::default(), 190 ctime: TimeSpec::default(), 191 file_type: file_type, 192 mode: 0o777, 193 nlinks: 1, 194 uid: 0, 195 gid: 0, 196 raw_dev: 0, 197 }, 198 }))); 199 200 inode.0.lock().self_ref = Arc::downgrade(&inode); 201 202 inode.0.lock().update_metadata(); 203 204 return inode; 205 } 206 } 207 208 /// 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） 209 #[derive(Debug)] 210 pub struct FATFsInfo { 211 /// Lead Signature - must equal 0x41615252 212 lead_sig: u32, 213 /// Value must equal 0x61417272 214 struc_sig: u32, 215 /// 空闲簇数目 216 free_count: u32, 217 /// 第一个空闲簇的位置（不一定准确，仅供加速查找） 218 next_free: u32, 219 /// 0xAA550000 220 trail_sig: u32, 221 /// Dirty flag to flush to disk 222 dirty: bool, 223 /// FsInfo Structure 在磁盘上的字节偏移量 224 /// Not present for FAT12 and FAT16 225 offset: Option<u64>, 226 } 227 228 impl FileSystem for FATFileSystem { 229 fn root_inode(&self) -> Arc<dyn crate::filesystem::vfs::IndexNode> { 230 return self.root_inode.clone(); 231 } 232 233 fn info(&self) -> crate::filesystem::vfs::FsInfo { 234 todo!() 235 } 236 237 /// @brief 本函数用于实现动态转换。 238 /// 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 239 fn as_any_ref(&self) -> &dyn Any { 240 self 241 } 242 } 243 244 impl FATFileSystem { 245 /// FAT12允许的最大簇号 246 pub const FAT12_MAX_CLUSTER: u32 = 0xFF5; 247 /// FAT16允许的最大簇号 248 pub const FAT16_MAX_CLUSTER: u32 = 0xFFF5; 249 /// FAT32允许的最大簇号 250 pub const FAT32_MAX_CLUSTER: u32 = 0x0FFFFFF7; 251 252 pub fn new(partition: Arc<Partition>) -> Result<Arc<FATFileSystem>, SystemError> { 253 let bpb = BiosParameterBlock::new(partition.clone())?; 254 255 // 从磁盘上读取FAT32文件系统的FsInfo结构体 256 let fs_info: FATFsInfo = match bpb.fat_type { 257 FATType::FAT32(bpb32) => { 258 let fs_info_in_disk_bytes_offset = partition.lba_start * LBA_SIZE as u64 259 + bpb32.fs_info as u64 * bpb.bytes_per_sector as u64; 260 FATFsInfo::new( 261 partition.clone(), 262 fs_info_in_disk_bytes_offset, 263 bpb.bytes_per_sector as usize, 264 )? 265 } 266 _ => FATFsInfo::default(), 267 }; 268 269 // 根目录项占用的扇区数（向上取整） 270 let root_dir_sectors: u64 = ((bpb.root_entries_cnt as u64 * 32) 271 + (bpb.bytes_per_sector as u64 - 1)) 272 / (bpb.bytes_per_sector as u64); 273 274 // FAT表大小（单位：扇区） 275 let fat_size = if bpb.fat_size_16 != 0 { 276 bpb.fat_size_16 as u64 277 } else { 278 match bpb.fat_type { 279 FATType::FAT32(x) => x.fat_size_32 as u64, 280 _ => { 281 kerror!("FAT12 and FAT16 volumes should have non-zero BPB_FATSz16"); 282 return Err(SystemError::EINVAL); 283 } 284 } 285 }; 286 287 let first_data_sector = 288 bpb.rsvd_sec_cnt as u64 + (bpb.num_fats as u64 * fat_size) + root_dir_sectors; 289 290 // 创建文件系统的根节点 291 let root_inode: Arc<LockedFATInode> = Arc::new(LockedFATInode(SpinLock::new(FATInode { 292 parent: Weak::default(), 293 self_ref: Weak::default(), 294 children: BTreeMap::new(), 295 fs: Weak::default(), 296 inode_type: FATDirEntry::UnInit, 297 metadata: Metadata { 298 dev_id: 0, 299 inode_id: generate_inode_id(), 300 size: 0, 301 blk_size: bpb.bytes_per_sector as usize, 302 blocks: if let FATType::FAT32(_) = bpb.fat_type { 303 bpb.total_sectors_32 as usize 304 } else { 305 bpb.total_sectors_16 as usize 306 }, 307 atime: TimeSpec::default(), 308 mtime: TimeSpec::default(), 309 ctime: TimeSpec::default(), 310 file_type: FileType::Dir, 311 mode: 0o777, 312 nlinks: 1, 313 uid: 0, 314 gid: 0, 315 raw_dev: 0, 316 }, 317 }))); 318 319 let result: Arc<FATFileSystem> = Arc::new(FATFileSystem { 320 partition: partition, 321 bpb, 322 first_data_sector, 323 fs_info: Arc::new(LockedFATFsInfo::new(fs_info)), 324 root_inode: root_inode, 325 }); 326 327 // 对root inode加锁，并继续完成初始化工作 328 let mut root_guard: SpinLockGuard<FATInode> = result.root_inode.0.lock(); 329 root_guard.inode_type = FATDirEntry::Dir(result.root_dir()); 330 root_guard.parent = Arc::downgrade(&result.root_inode); 331 root_guard.self_ref = Arc::downgrade(&result.root_inode); 332 root_guard.fs = Arc::downgrade(&result); 333 // 释放锁 334 drop(root_guard); 335 336 return Ok(result); 337 } 338 339 /// @brief 计算每个簇有多少个字节 340 #[inline] 341 pub fn bytes_per_cluster(&self) -> u64 { 342 return (self.bpb.bytes_per_sector as u64) * (self.bpb.sector_per_cluster as u64); 343 } 344 345 /// @brief 读取当前簇在FAT表中存储的信息 346 /// 347 /// @param cluster 当前簇 348 /// 349 /// @return Ok(FATEntry) 当前簇在FAT表中，存储的信息。（详情见FATEntry的注释） 350 /// @return Err(SystemError) 错误码 351 pub fn get_fat_entry(&self, cluster: Cluster) -> Result<FATEntry, SystemError> { 352 let current_cluster = cluster.cluster_num; 353 if current_cluster < 2 { 354 // 0号簇和1号簇是保留簇，不允许用户使用 355 return Err(SystemError::EINVAL); 356 } 357 358 let fat_type: FATType = self.bpb.fat_type; 359 // 获取FAT表的起始扇区（相对分区起始扇区的偏移量） 360 let fat_start_sector = self.fat_start_sector(); 361 let bytes_per_sec = self.bpb.bytes_per_sector as u64; 362 363 // cluster对应的FAT表项在分区内的字节偏移量 364 let fat_bytes_offset = 365 fat_type.get_fat_bytes_offset(cluster, fat_start_sector, bytes_per_sec); 366 367 // FAT表项所在的LBA地址 368 // let fat_ent_lba = self.get_lba_from_offset(self.bytes_to_sector(fat_bytes_offset)); 369 let fat_ent_lba = self.partition.lba_start + fat_bytes_offset / LBA_SIZE as u64; 370 371 // FAT表项在逻辑块内的字节偏移量 372 let blk_offset = self.get_in_block_offset(fat_bytes_offset); 373 374 let mut v = Vec::<u8>::new(); 375 v.resize(self.bpb.bytes_per_sector as usize, 0); 376 self.partition 377 .disk() 378 .read_at(fat_ent_lba as usize, 1 * self.lba_per_sector(), &mut v)?; 379 380 let mut cursor = VecCursor::new(v); 381 cursor.seek(SeekFrom::SeekSet(blk_offset as i64))?; 382 383 let res: FATEntry = match self.bpb.fat_type { 384 FATType::FAT12(_) => { 385 let mut entry = cursor.read_u16()?; 386 // 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。 387 if (current_cluster & 1) > 0 { 388 entry >>= 4; 389 } else { 390 entry &= 0x0fff; 391 } 392 393 if entry == 0 { 394 FATEntry::Unused 395 } else if entry == 0x0ff7 { 396 FATEntry::Bad 397 } else if entry >= 0x0ff8 { 398 FATEntry::EndOfChain 399 } else { 400 FATEntry::Next(Cluster { 401 cluster_num: entry as u64, 402 parent_cluster: current_cluster, 403 }) 404 } 405 } 406 FATType::FAT16(_) => { 407 let entry = cursor.read_u16()?; 408 409 if entry == 0 { 410 FATEntry::Unused 411 } else if entry == 0xfff7 { 412 FATEntry::Bad 413 } else if entry >= 0xfff8 { 414 FATEntry::EndOfChain 415 } else { 416 FATEntry::Next(Cluster { 417 cluster_num: entry as u64, 418 parent_cluster: current_cluster, 419 }) 420 } 421 } 422 FATType::FAT32(_) => { 423 let entry = cursor.read_u32()? & 0x0fffffff; 424 425 match entry { 426 _n if (current_cluster >= 0x0ffffff7 && current_cluster <= 0x0fffffff) => { 427 // 当前簇号不是一个能被获得的簇（可能是文件系统出错了） 428 kerror!("FAT32 get fat entry: current cluster number [{}] is not an allocatable cluster number.", current_cluster); 429 FATEntry::Bad 430 } 431 0 => FATEntry::Unused, 432 0x0ffffff7 => FATEntry::Bad, 433 0x0ffffff8..=0x0fffffff => FATEntry::EndOfChain, 434 _n => FATEntry::Next(Cluster { 435 cluster_num: entry as u64, 436 parent_cluster: current_cluster, 437 }), 438 } 439 } 440 }; 441 return Ok(res); 442 } 443 444 /// @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） 445 /// 446 /// @param cluster 当前簇 447 /// 448 /// @return Ok(u64) 当前簇在FAT表中，存储的信息。 449 /// @return Err(SystemError) 错误码 450 pub fn get_fat_entry_raw(&self, cluster: Cluster) -> Result<u64, SystemError> { 451 let current_cluster = cluster.cluster_num; 452 453 let fat_type: FATType = self.bpb.fat_type; 454 // 获取FAT表的起始扇区（相对分区起始扇区的偏移量） 455 let fat_start_sector = self.fat_start_sector(); 456 let bytes_per_sec = self.bpb.bytes_per_sector as u64; 457 458 // cluster对应的FAT表项在分区内的字节偏移量 459 let fat_bytes_offset = 460 fat_type.get_fat_bytes_offset(cluster, fat_start_sector, bytes_per_sec); 461 462 // FAT表项所在的LBA地址 463 let fat_ent_lba = self.get_lba_from_offset(self.bytes_to_sector(fat_bytes_offset)); 464 465 // FAT表项在逻辑块内的字节偏移量 466 let blk_offset = self.get_in_block_offset(fat_bytes_offset); 467 468 let mut v = Vec::<u8>::new(); 469 v.resize(self.bpb.bytes_per_sector as usize, 0); 470 self.partition 471 .disk() 472 .read_at(fat_ent_lba, 1 * self.lba_per_sector(), &mut v)?; 473 474 let mut cursor = VecCursor::new(v); 475 cursor.seek(SeekFrom::SeekSet(blk_offset as i64))?; 476 477 let res = match self.bpb.fat_type { 478 FATType::FAT12(_) => { 479 let mut entry = cursor.read_u16()?; 480 entry = if (current_cluster & 0x0001) > 0 { 481 entry >> 4 482 } else { 483 entry & 0x0fff 484 }; 485 entry as u64 486 } 487 FATType::FAT16(_) => { 488 let entry = (cursor.read_u16()?) as u64; 489 entry 490 } 491 FATType::FAT32(_) => { 492 let entry = cursor.read_u32()? & 0x0fff_ffff; 493 entry as u64 494 } 495 }; 496 497 return Ok(res); 498 } 499 500 /// @brief 获取当前文件系统的root inode，在磁盘上的字节偏移量 501 pub fn root_dir_bytes_offset(&self) -> u64 { 502 match self.bpb.fat_type { 503 FATType::FAT32(s) => { 504 let first_sec_cluster: u64 = (s.root_cluster as u64 - 2) 505 * (self.bpb.sector_per_cluster as u64) 506 + self.first_data_sector; 507 return (self.get_lba_from_offset(first_sec_cluster) * LBA_SIZE) as u64; 508 } 509 _ => { 510 let root_sec = (self.bpb.rsvd_sec_cnt as u64) 511 + (self.bpb.num_fats as u64) * (self.bpb.fat_size_16 as u64); 512 return (self.get_lba_from_offset(root_sec) * LBA_SIZE) as u64; 513 } 514 } 515 } 516 517 /// @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。 518 /// 请注意，当前函数只对FAT12/FAT16生效。对于FAT32,返回None 519 pub fn root_dir_end_bytes_offset(&self) -> Option<u64> { 520 match self.bpb.fat_type { 521 FATType::FAT12(_) | FATType::FAT16(_) => { 522 return Some( 523 self.root_dir_bytes_offset() + (self.bpb.root_entries_cnt as u64) * 32, 524 ); 525 } 526 _ => { 527 return None; 528 } 529 } 530 } 531 532 /// @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) 533 pub fn cluster_bytes_offset(&self, cluster: Cluster) -> u64 { 534 if cluster.cluster_num >= 2 { 535 // 指定簇的第一个扇区号 536 let first_sec_of_cluster = (cluster.cluster_num - 2) 537 * (self.bpb.sector_per_cluster as u64) 538 + self.first_data_sector; 539 return (self.get_lba_from_offset(first_sec_of_cluster) * LBA_SIZE) as u64; 540 } else { 541 return 0; 542 } 543 } 544 545 /// @brief 获取一个空闲簇 546 /// 547 /// @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。 548 /// 549 /// @return Ok(Cluster) 新获取的空闲簇 550 /// @return Err(SystemError) 错误码 551 pub fn allocate_cluster(&self, prev_cluster: Option<Cluster>) -> Result<Cluster, SystemError> { 552 let end_cluster: Cluster = self.max_cluster_number(); 553 let start_cluster: Cluster = match self.bpb.fat_type { 554 FATType::FAT32(_) => { 555 let next_free: u64 = match self.fs_info.0.lock().next_free() { 556 Some(x) => x, 557 None => 0xffffffff, 558 }; 559 if next_free < end_cluster.cluster_num { 560 Cluster::new(next_free) 561 } else { 562 Cluster::new(RESERVED_CLUSTERS as u64) 563 } 564 } 565 _ => Cluster::new(RESERVED_CLUSTERS as u64), 566 }; 567 568 // 寻找一个空的簇 569 let free_cluster: Cluster = match self.get_free_cluster(start_cluster, end_cluster) { 570 Ok(c) => c, 571 Err(_) if start_cluster.cluster_num > RESERVED_CLUSTERS as u64 => { 572 self.get_free_cluster(Cluster::new(RESERVED_CLUSTERS as u64), end_cluster)? 573 } 574 Err(e) => return Err(e), 575 }; 576 577 self.set_entry(free_cluster, FATEntry::EndOfChain)?; 578 // 减少空闲簇计数 579 self.fs_info.0.lock().update_free_count_delta(-1); 580 // 更新搜索空闲簇的参考量 581 self.fs_info 582 .0 583 .lock() 584 .update_next_free((free_cluster.cluster_num + 1) as u32); 585 586 // 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。 587 if let Some(prev_cluster) = prev_cluster { 588 // kdebug!("set entry, prev ={prev_cluster:?}, next = {free_cluster:?}"); 589 self.set_entry(prev_cluster, FATEntry::Next(free_cluster))?; 590 } 591 // 清空新获取的这个簇 592 self.zero_cluster(free_cluster)?; 593 return Ok(free_cluster); 594 } 595 596 /// @brief 释放簇链上的所有簇 597 /// 598 /// @param start_cluster 簇链的第一个簇 599 pub fn deallocate_cluster_chain(&self, start_cluster: Cluster) -> Result<(), SystemError> { 600 let clusters: Vec<Cluster> = self.clusters(start_cluster); 601 for c in clusters { 602 self.deallocate_cluster(c)?; 603 } 604 return Ok(()); 605 } 606 607 /// @brief 释放簇 608 /// 609 /// @param 要释放的簇 610 pub fn deallocate_cluster(&self, cluster: Cluster) -> Result<(), SystemError> { 611 let entry: FATEntry = self.get_fat_entry(cluster)?; 612 // 如果不是坏簇 613 if entry != FATEntry::Bad { 614 self.set_entry(cluster, FATEntry::Unused)?; 615 self.fs_info.0.lock().update_free_count_delta(1); 616 // 安全选项：清空被释放的簇 617 #[cfg(feature = "secure")] 618 self.zero_cluster(cluster)?; 619 return Ok(()); 620 } else { 621 // 不能释放坏簇 622 kerror!("Bad clusters cannot be freed."); 623 return Err(SystemError::EFAULT); 624 } 625 } 626 627 /// @brief 获取文件系统的根目录项 628 pub fn root_dir(&self) -> FATDir { 629 match self.bpb.fat_type { 630 FATType::FAT32(s) => { 631 return FATDir { 632 first_cluster: Cluster::new(s.root_cluster as u64), 633 dir_name: String::from("/"), 634 root_offset: None, 635 short_dir_entry: None, 636 loc: None, 637 }; 638 } 639 _ => FATDir { 640 first_cluster: Cluster::new(0), 641 dir_name: String::from("/"), 642 root_offset: Some(self.root_dir_bytes_offset()), 643 short_dir_entry: None, 644 loc: None, 645 }, 646 } 647 } 648 649 /// @brief 获取FAT表的起始扇区（相对分区起始扇区的偏移量） 650 pub fn fat_start_sector(&self) -> u64 { 651 let active_fat = self.active_fat(); 652 let fat_size = self.fat_size(); 653 return self.bpb.rsvd_sec_cnt as u64 + active_fat * fat_size; 654 } 655 656 /// @brief 获取当前活动的FAT表 657 pub fn active_fat(&self) -> u64 { 658 if self.mirroring_enabled() { 659 return 0; 660 } else { 661 match self.bpb.fat_type { 662 FATType::FAT32(bpb32) => { 663 return (bpb32.ext_flags & 0x0f) as u64; 664 } 665 _ => { 666 return 0; 667 } 668 } 669 } 670 } 671 672 /// @brief 获取当前文件系统的每个FAT表的大小 673 pub fn fat_size(&self) -> u64 { 674 if self.bpb.fat_size_16 != 0 { 675 return self.bpb.fat_size_16 as u64; 676 } else { 677 match self.bpb.fat_type { 678 FATType::FAT32(bpb32) => { 679 return bpb32.fat_size_32 as u64; 680 } 681 682 _ => { 683 panic!("FAT12 and FAT16 volumes should have non-zero BPB_FATSz16"); 684 } 685 } 686 } 687 } 688 689 /// @brief 判断当前文件系统是否启用了FAT表镜像 690 pub fn mirroring_enabled(&self) -> bool { 691 match self.bpb.fat_type { 692 FATType::FAT32(bpb32) => { 693 return (bpb32.ext_flags & 0x80) == 0; 694 } 695 _ => { 696 return false; 697 } 698 } 699 } 700 701 /// @brief 根据分区内的扇区偏移量，获得在磁盘上的LBA地址 702 #[inline] 703 pub fn get_lba_from_offset(&self, in_partition_sec_offset: u64) -> usize { 704 return (self.partition.lba_start 705 + in_partition_sec_offset * (self.bpb.bytes_per_sector as u64 / LBA_SIZE as u64)) 706 as usize; 707 } 708 709 /// @brief 获取每个扇区占用多少个LBA 710 #[inline] 711 pub fn lba_per_sector(&self) -> usize { 712 return self.bpb.bytes_per_sector as usize / LBA_SIZE; 713 } 714 715 /// @brief 将分区内字节偏移量转换为扇区偏移量 716 #[inline] 717 pub fn bytes_to_sector(&self, in_partition_bytes_offset: u64) -> u64 { 718 return in_partition_bytes_offset / (self.bpb.bytes_per_sector as u64); 719 } 720 721 /// @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 722 #[inline] 723 pub fn get_in_partition_bytes_offset(&self, disk_bytes_offset: u64) -> u64 { 724 return disk_bytes_offset - (self.partition.lba_start * LBA_SIZE as u64); 725 } 726 727 /// @brief 根据字节偏移量计算在逻辑块内的字节偏移量 728 #[inline] 729 pub fn get_in_block_offset(&self, bytes_offset: u64) -> u64 { 730 return bytes_offset % LBA_SIZE as u64; 731 } 732 733 /// @brief 获取在FAT表中，以start_cluster开头的FAT链的所有簇的信息 734 /// 735 /// @param start_cluster 整个FAT链的起始簇号 736 pub fn clusters(&self, start_cluster: Cluster) -> Vec<Cluster> { 737 return self.cluster_iter(start_cluster).collect(); 738 } 739 740 /// @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） 741 /// 742 /// @param start_cluster 整个FAT链的起始簇号 743 pub fn num_clusters_chain(&self, start_cluster: Cluster) -> u64 { 744 return self 745 .cluster_iter(start_cluster) 746 .fold(0, |size, _cluster| size + 1); 747 } 748 /// @brief 获取一个簇迭代器对象 749 /// 750 /// @param start_cluster 整个FAT链的起始簇号 751 fn cluster_iter(&self, start_cluster: Cluster) -> ClusterIter { 752 return ClusterIter { 753 current_cluster: Some(start_cluster), 754 fs: self, 755 }; 756 } 757 758 /// @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） 759 #[inline] 760 pub fn get_cluster_by_relative(&self, start_cluster: Cluster, n: usize) -> Option<Cluster> { 761 return self.cluster_iter(start_cluster).skip(n).next(); 762 } 763 764 /// @brief 获取整个簇链的最后一个簇 765 #[inline] 766 pub fn get_last_cluster(&self, start_cluster: Cluster) -> Option<Cluster> { 767 return self.cluster_iter(start_cluster).last(); 768 } 769 770 /// @brief 判断FAT文件系统的shut bit是否正常。 771 /// 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” 772 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 773 /// 774 /// @return Ok(true) 正常 775 /// @return Ok(false) 不正常 776 /// @return Err(SystemError) 在判断时发生错误 777 pub fn is_shut_bit_ok(&mut self) -> Result<bool, SystemError> { 778 match self.bpb.fat_type { 779 FATType::FAT32(_) => { 780 // 对于FAT32, error bit位于第一个扇区的第8字节。 781 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0800_0000; 782 return Ok(bit > 0); 783 } 784 FATType::FAT16(_) => { 785 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x8000; 786 return Ok(bit > 0); 787 } 788 _ => return Ok(true), 789 } 790 } 791 792 /// @brief 判断FAT文件系统的hard error bit是否正常。 793 /// 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 794 /// 卷上的某些扇区可能已损坏。 795 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 796 /// 797 /// @return Ok(true) 正常 798 /// @return Ok(false) 不正常 799 /// @return Err(SystemError) 在判断时发生错误 800 pub fn is_hard_error_bit_ok(&mut self) -> Result<bool, SystemError> { 801 match self.bpb.fat_type { 802 FATType::FAT32(_) => { 803 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0400_0000; 804 return Ok(bit > 0); 805 } 806 FATType::FAT16(_) => { 807 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x4000; 808 return Ok(bit > 0); 809 } 810 _ => return Ok(true), 811 } 812 } 813 814 /// @brief 设置文件系统的shut bit为正常状态 815 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 816 /// 817 /// @return Ok(()) 设置成功 818 /// @return Err(SystemError) 在设置过程中，出现错误 819 pub fn set_shut_bit_ok(&mut self) -> Result<(), SystemError> { 820 match self.bpb.fat_type { 821 FATType::FAT32(_) => { 822 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0800_0000; 823 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 824 825 return Ok(()); 826 } 827 828 FATType::FAT16(_) => { 829 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x8000; 830 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 831 return Ok(()); 832 } 833 _ => return Ok(()), 834 } 835 } 836 837 /// @brief 设置文件系统的hard error bit为正常状态 838 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 839 /// 840 /// @return Ok(()) 设置成功 841 /// @return Err(SystemError) 在设置过程中，出现错误 842 pub fn set_hard_error_bit_ok(&mut self) -> Result<(), SystemError> { 843 match self.bpb.fat_type { 844 FATType::FAT32(_) => { 845 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0400_0000; 846 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 847 return Ok(()); 848 } 849 850 FATType::FAT16(_) => { 851 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x4000; 852 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 853 return Ok(()); 854 } 855 _ => return Ok(()), 856 } 857 } 858 859 /// @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 860 pub fn umount(&mut self) -> Result<(), SystemError> { 861 self.fs_info.0.lock().flush(&self.partition)?; 862 863 self.set_shut_bit_ok()?; 864 865 self.set_hard_error_bit_ok()?; 866 867 self.partition.disk().sync()?; 868 869 return Ok(()); 870 } 871 872 /// @brief 获取文件系统的最大簇号 873 pub fn max_cluster_number(&self) -> Cluster { 874 match self.bpb.fat_type { 875 FATType::FAT32(s) => { 876 // FAT32 877 878 // 数据扇区数量（总扇区数-保留扇区-FAT占用的扇区） 879 let data_sec: u64 = self.bpb.total_sectors_32 as u64 880 - (self.bpb.rsvd_sec_cnt as u64 881 + self.bpb.num_fats as u64 * s.fat_size_32 as u64); 882 883 // 数据区的簇数量 884 let total_clusters: u64 = data_sec / self.bpb.sector_per_cluster as u64; 885 886 // 返回最大的簇号 887 return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); 888 } 889 890 _ => { 891 // FAT12 / FAT16 892 let root_dir_sectors: u64 = (((self.bpb.root_entries_cnt as u64) * 32) 893 + self.bpb.bytes_per_sector as u64 894 - 1) 895 / self.bpb.bytes_per_sector as u64; 896 // 数据区扇区数 897 let data_sec: u64 = self.bpb.total_sectors_16 as u64 898 - (self.bpb.rsvd_sec_cnt as u64 899 + (self.bpb.num_fats as u64 * self.bpb.fat_size_16 as u64) 900 + root_dir_sectors); 901 let total_clusters = data_sec / self.bpb.sector_per_cluster as u64; 902 return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); 903 } 904 } 905 } 906 907 /// @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 908 /// 909 /// @param start_cluster 起始簇号 910 /// @param end_cluster 终止簇号（不包含） 911 /// 912 /// @return Ok(Cluster) 寻找到的空闲簇 913 /// @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. 914 pub fn get_free_cluster( 915 &self, 916 start_cluster: Cluster, 917 end_cluster: Cluster, 918 ) -> Result<Cluster, SystemError> { 919 let max_cluster: Cluster = self.max_cluster_number(); 920 let mut cluster: u64 = start_cluster.cluster_num; 921 922 let fat_type: FATType = self.bpb.fat_type; 923 let fat_start_sector: u64 = self.fat_start_sector(); 924 let bytes_per_sec: u64 = self.bpb.bytes_per_sector as u64; 925 926 match fat_type { 927 FATType::FAT12(_) => { 928 let part_bytes_offset: u64 = 929 fat_type.get_fat_bytes_offset(start_cluster, fat_start_sector, bytes_per_sec); 930 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 931 932 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 933 934 // 由于FAT12的FAT表不大于6K，因此直接读取6K 935 let num_lba = (6 * 1024) / LBA_SIZE; 936 let mut v: Vec<u8> = Vec::new(); 937 v.resize(num_lba * LBA_SIZE, 0); 938 self.partition.disk().read_at(lba, num_lba, &mut v)?; 939 940 let mut cursor: VecCursor = VecCursor::new(v); 941 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 942 943 let mut packed_val: u16 = cursor.read_u16()?; 944 loop { 945 let val = if (cluster & 0x1) > 0 { 946 packed_val >> 4 947 } else { 948 packed_val & 0x0fff 949 }; 950 if val == 0 { 951 return Ok(Cluster::new(cluster as u64)); 952 } 953 954 cluster += 1; 955 956 // 磁盘无剩余空间，或者簇号达到给定的最大值 957 if cluster == end_cluster.cluster_num || cluster == max_cluster.cluster_num { 958 return Err(SystemError::ENOSPC); 959 } 960 961 packed_val = match cluster & 1 { 962 0 => cursor.read_u16()?, 963 _ => { 964 let next_byte = cursor.read_u8()? as u16; 965 (packed_val >> 8) | (next_byte << 8) 966 } 967 }; 968 } 969 } 970 FATType::FAT16(_) => { 971 // todo: 优化这里，减少读取磁盘的次数。 972 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { 973 let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( 974 Cluster::new(cluster), 975 fat_start_sector, 976 bytes_per_sec, 977 ); 978 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 979 980 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 981 982 let mut v: Vec<u8> = Vec::new(); 983 v.resize(self.lba_per_sector() * LBA_SIZE, 0); 984 self.partition 985 .disk() 986 .read_at(lba, self.lba_per_sector(), &mut v)?; 987 988 let mut cursor: VecCursor = VecCursor::new(v); 989 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 990 991 let val = cursor.read_u16()?; 992 // 找到空闲簇 993 if val == 0 { 994 return Ok(Cluster::new(val as u64)); 995 } 996 cluster += 1; 997 } 998 999 // 磁盘无剩余空间，或者簇号达到给定的最大值 1000 return Err(SystemError::ENOSPC); 1001 } 1002 FATType::FAT32(_) => { 1003 // todo: 优化这里，减少读取磁盘的次数。 1004 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { 1005 let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( 1006 Cluster::new(cluster), 1007 fat_start_sector, 1008 bytes_per_sec, 1009 ); 1010 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 1011 1012 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 1013 1014 let mut v: Vec<u8> = Vec::new(); 1015 v.resize(self.lba_per_sector() * LBA_SIZE, 0); 1016 self.partition 1017 .disk() 1018 .read_at(lba, self.lba_per_sector(), &mut v)?; 1019 1020 let mut cursor: VecCursor = VecCursor::new(v); 1021 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1022 1023 let val = cursor.read_u32()? & 0x0fffffff; 1024 1025 if val == 0 { 1026 return Ok(Cluster::new(cluster)); 1027 } 1028 cluster += 1; 1029 } 1030 1031 // 磁盘无剩余空间，或者簇号达到给定的最大值 1032 return Err(SystemError::ENOSPC); 1033 } 1034 } 1035 } 1036 1037 /// @brief 在FAT表中，设置指定的簇的信息。 1038 /// 1039 /// @param cluster 目标簇 1040 /// @param fat_entry 这个簇在FAT表中，存储的信息（下一个簇的簇号） 1041 pub fn set_entry(&self, cluster: Cluster, fat_entry: FATEntry) -> Result<(), SystemError> { 1042 // fat表项在分区上的字节偏移量 1043 let fat_part_bytes_offset: u64 = self.bpb.fat_type.get_fat_bytes_offset( 1044 cluster, 1045 self.fat_start_sector(), 1046 self.bpb.bytes_per_sector as u64, 1047 ); 1048 1049 match self.bpb.fat_type { 1050 FATType::FAT12(_) => { 1051 // 计算要写入的值 1052 let raw_val: u16 = match fat_entry { 1053 FATEntry::Unused => 0, 1054 FATEntry::Bad => 0xff7, 1055 FATEntry::EndOfChain => 0xfff, 1056 FATEntry::Next(c) => c.cluster_num as u16, 1057 }; 1058 1059 let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); 1060 1061 let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); 1062 1063 let mut v: Vec<u8> = Vec::new(); 1064 v.resize(LBA_SIZE, 0); 1065 self.partition.disk().read_at(lba, 1, &mut v)?; 1066 1067 let mut cursor: VecCursor = VecCursor::new(v); 1068 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1069 1070 let old_val: u16 = cursor.read_u16()?; 1071 let new_val: u16 = if (cluster.cluster_num & 0x1) > 0 { 1072 (old_val & 0x000f) | (raw_val << 4) 1073 } else { 1074 (old_val & 0xf000) | raw_val 1075 }; 1076 1077 // 写回数据到磁盘上 1078 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1079 cursor.write_u16(new_val)?; 1080 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1081 return Ok(()); 1082 } 1083 FATType::FAT16(_) => { 1084 // 计算要写入的值 1085 let raw_val: u16 = match fat_entry { 1086 FATEntry::Unused => 0, 1087 FATEntry::Bad => 0xfff7, 1088 FATEntry::EndOfChain => 0xfdff, 1089 FATEntry::Next(c) => c.cluster_num as u16, 1090 }; 1091 1092 let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); 1093 1094 let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); 1095 1096 let mut v: Vec<u8> = Vec::new(); 1097 v.resize(LBA_SIZE, 0); 1098 self.partition.disk().read_at(lba, 1, &mut v)?; 1099 1100 let mut cursor: VecCursor = VecCursor::new(v); 1101 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1102 1103 cursor.write_u16(raw_val)?; 1104 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1105 1106 return Ok(()); 1107 } 1108 FATType::FAT32(_) => { 1109 let fat_size: u64 = self.fat_size(); 1110 let bound: u64 = if self.mirroring_enabled() { 1111 1 1112 } else { 1113 self.bpb.num_fats as u64 1114 }; 1115 // kdebug!("set entry, bound={bound}, fat_size={fat_size}"); 1116 for i in 0..bound { 1117 // 当前操作的FAT表在磁盘上的字节偏移量 1118 let f_offset: u64 = fat_part_bytes_offset + i * fat_size; 1119 let in_block_offset: u64 = self.get_in_block_offset(f_offset); 1120 let lba = self.get_lba_from_offset(self.bytes_to_sector(f_offset)); 1121 1122 // kdebug!("set entry, lba={lba}, in_block_offset={in_block_offset}"); 1123 let mut v: Vec<u8> = Vec::new(); 1124 v.resize(LBA_SIZE, 0); 1125 self.partition.disk().read_at(lba, 1, &mut v)?; 1126 1127 let mut cursor: VecCursor = VecCursor::new(v); 1128 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1129 1130 // FAT32的高4位保留 1131 let old_bits = cursor.read_u32()? & 0xf0000000; 1132 1133 if fat_entry == FATEntry::Unused 1134 && cluster.cluster_num >= 0x0ffffff7 1135 && cluster.cluster_num <= 0x0fffffff 1136 { 1137 kerror!( 1138 "FAT32: Reserved Cluster {:?} cannot be marked as free", 1139 cluster 1140 ); 1141 return Err(SystemError::EPERM); 1142 } 1143 1144 // 计算要写入的值 1145 let mut raw_val: u32 = match fat_entry { 1146 FATEntry::Unused => 0, 1147 FATEntry::Bad => 0x0FFFFFF7, 1148 FATEntry::EndOfChain => 0x0FFFFFFF, 1149 FATEntry::Next(c) => c.cluster_num as u32, 1150 }; 1151 1152 // 恢复保留位 1153 raw_val |= old_bits; 1154 1155 // kdebug!("sent entry, raw_val={raw_val}"); 1156 1157 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1158 cursor.write_u32(raw_val)?; 1159 1160 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1161 } 1162 1163 return Ok(()); 1164 } 1165 } 1166 } 1167 1168 /// @brief 清空指定的簇 1169 /// 1170 /// @param cluster 要被清空的簇 1171 pub fn zero_cluster(&self, cluster: Cluster) -> Result<(), SystemError> { 1172 // 准备数据，用于写入 1173 let zeros: Vec<u8> = vec![0u8; self.bytes_per_cluster() as usize]; 1174 let offset: usize = self.cluster_bytes_offset(cluster) as usize; 1175 self.partition 1176 .disk() 1177 .device() 1178 .write_at(offset, zeros.len(), zeros.as_slice())?; 1179 return Ok(()); 1180 } 1181 } 1182 1183 impl Drop for FATFileSystem { 1184 fn drop(&mut self) { 1185 let r = self.umount(); 1186 if r.is_err() { 1187 kerror!( 1188 "Umount FAT filesystem failed: errno={:?}, FS detail:{self:?}", 1189 r.unwrap_err() 1190 ); 1191 } 1192 } 1193 } 1194 1195 impl FATFsInfo { 1196 const LEAD_SIG: u32 = 0x41615252; 1197 const STRUC_SIG: u32 = 0x61417272; 1198 const TRAIL_SIG: u32 = 0xAA550000; 1199 const FS_INFO_SIZE: u64 = 512; 1200 1201 /// @brief 从磁盘上读取FAT文件系统的FSInfo结构体 1202 /// 1203 /// @param partition 磁盘分区 1204 /// @param in_disk_fs_info_offset FSInfo扇区在磁盘内的字节偏移量（单位：字节） 1205 /// @param bytes_per_sec 每扇区字节数 1206 pub fn new( 1207 partition: Arc<Partition>, 1208 in_disk_fs_info_offset: u64, 1209 bytes_per_sec: usize, 1210 ) -> Result<Self, SystemError> { 1211 let mut v = Vec::<u8>::new(); 1212 v.resize(bytes_per_sec, 0); 1213 1214 // 计算fs_info扇区在磁盘上的字节偏移量，从磁盘读取数据 1215 partition 1216 .disk() 1217 .read_at(in_disk_fs_info_offset as usize / LBA_SIZE, 1, &mut v)?; 1218 let mut cursor = VecCursor::new(v); 1219 1220 let mut fsinfo = FATFsInfo::default(); 1221 1222 fsinfo.lead_sig = cursor.read_u32()?; 1223 cursor.seek(SeekFrom::SeekCurrent(480))?; 1224 fsinfo.struc_sig = cursor.read_u32()?; 1225 fsinfo.free_count = cursor.read_u32()?; 1226 fsinfo.next_free = cursor.read_u32()?; 1227 1228 cursor.seek(SeekFrom::SeekCurrent(12))?; 1229 1230 fsinfo.trail_sig = cursor.read_u32()?; 1231 fsinfo.dirty = false; 1232 fsinfo.offset = Some(in_disk_fs_info_offset); 1233 1234 if fsinfo.is_valid() { 1235 return Ok(fsinfo); 1236 } else { 1237 kerror!("Error occurred while parsing FATFsInfo."); 1238 return Err(SystemError::EINVAL); 1239 } 1240 } 1241 1242 /// @brief 判断是否为正确的FsInfo结构体 1243 fn is_valid(&self) -> bool { 1244 self.lead_sig == Self::LEAD_SIG 1245 && self.struc_sig == Self::STRUC_SIG 1246 && self.trail_sig == Self::TRAIL_SIG 1247 } 1248 1249 /// @brief 根据fsinfo的信息，计算当前总的空闲簇数量 1250 /// 1251 /// @param 当前文件系统的最大簇号 1252 pub fn count_free_cluster(&self, max_cluster: Cluster) -> Option<u64> { 1253 let count_clusters = max_cluster.cluster_num - RESERVED_CLUSTERS as u64 + 1; 1254 // 信息不合理，当前的FsInfo中存储的free count大于计算出来的值 1255 if self.free_count as u64 > count_clusters { 1256 return None; 1257 } else { 1258 match self.free_count { 1259 // free count字段不可用 1260 0xffffffff => return None, 1261 // 返回FsInfo中存储的数据 1262 n => return Some(n as u64), 1263 } 1264 } 1265 } 1266 1267 /// @brief 更新FsInfo中的“空闲簇统计信息“为new_count 1268 /// 1269 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 1270 pub fn update_free_count_abs(&mut self, new_count: u32) { 1271 self.free_count = new_count; 1272 } 1273 1274 /// @brief 更新FsInfo中的“空闲簇统计信息“，把它加上delta. 1275 /// 1276 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 1277 pub fn update_free_count_delta(&mut self, delta: i32) { 1278 self.free_count = (self.free_count as i32 + delta) as u32; 1279 } 1280 1281 /// @brief 更新FsInfo中的“第一个空闲簇统计信息“为next_free. 1282 /// 1283 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 1284 pub fn update_next_free(&mut self, next_free: u32) { 1285 // 这个值是参考量，不一定要准确，仅供加速查找 1286 self.next_free = next_free; 1287 } 1288 1289 /// @brief 获取fs info 记载的第一个空闲簇。（不一定准确，仅供参考） 1290 pub fn next_free(&self) -> Option<u64> { 1291 match self.next_free { 1292 0xffffffff => return None, 1293 0 | 1 => return None, 1294 n => return Some(n as u64), 1295 }; 1296 } 1297 1298 /// @brief 把fs info刷入磁盘 1299 /// 1300 /// @param partition fs info所在的分区 1301 pub fn flush(&self, partition: &Arc<Partition>) -> Result<(), SystemError> { 1302 if let Some(off) = self.offset { 1303 let in_block_offset = off % LBA_SIZE as u64; 1304 1305 let lba = off as usize / LBA_SIZE; 1306 1307 let mut v: Vec<u8> = Vec::new(); 1308 v.resize(LBA_SIZE, 0); 1309 partition.disk().read_at(lba, 1, &mut v)?; 1310 1311 let mut cursor: VecCursor = VecCursor::new(v); 1312 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1313 1314 cursor.write_u32(self.lead_sig)?; 1315 cursor.seek(SeekFrom::SeekCurrent(480))?; 1316 cursor.write_u32(self.struc_sig)?; 1317 cursor.write_u32(self.free_count)?; 1318 cursor.write_u32(self.next_free)?; 1319 cursor.seek(SeekFrom::SeekCurrent(12))?; 1320 cursor.write_u32(self.trail_sig)?; 1321 1322 partition.disk().write_at(lba, 1, cursor.as_slice())?; 1323 } 1324 return Ok(()); 1325 } 1326 1327 /// @brief 读取磁盘上的Fs Info扇区，将里面的内容更新到结构体中 1328 /// 1329 /// @param partition fs info所在的分区 1330 pub fn update(&mut self, partition: Arc<Partition>) -> Result<(), SystemError> { 1331 if let Some(off) = self.offset { 1332 let in_block_offset = off % LBA_SIZE as u64; 1333 1334 let lba = off as usize / LBA_SIZE; 1335 1336 let mut v: Vec<u8> = Vec::new(); 1337 v.resize(LBA_SIZE, 0); 1338 partition.disk().read_at(lba, 1, &mut v)?; 1339 let mut cursor: VecCursor = VecCursor::new(v); 1340 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1341 self.lead_sig = cursor.read_u32()?; 1342 1343 cursor.seek(SeekFrom::SeekCurrent(480))?; 1344 self.struc_sig = cursor.read_u32()?; 1345 self.free_count = cursor.read_u32()?; 1346 self.next_free = cursor.read_u32()?; 1347 cursor.seek(SeekFrom::SeekCurrent(12))?; 1348 self.trail_sig = cursor.read_u32()?; 1349 } 1350 return Ok(()); 1351 } 1352 } 1353 1354 impl IndexNode for LockedFATInode { 1355 fn read_at( 1356 &self, 1357 offset: usize, 1358 len: usize, 1359 buf: &mut [u8], 1360 _data: &mut FilePrivateData, 1361 ) -> Result<usize, SystemError> { 1362 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1363 match &guard.inode_type { 1364 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 1365 let r = f.read( 1366 &guard.fs.upgrade().unwrap(), 1367 &mut buf[0..len], 1368 offset as u64, 1369 ); 1370 guard.update_metadata(); 1371 return r; 1372 } 1373 FATDirEntry::Dir(_) => { 1374 return Err(SystemError::EISDIR); 1375 } 1376 FATDirEntry::UnInit => { 1377 kerror!("FATFS: param: Inode_type uninitialized."); 1378 return Err(SystemError::EROFS); 1379 } 1380 } 1381 } 1382 1383 fn write_at( 1384 &self, 1385 offset: usize, 1386 len: usize, 1387 buf: &[u8], 1388 _data: &mut FilePrivateData, 1389 ) -> Result<usize, SystemError> { 1390 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1391 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1392 1393 match &mut guard.inode_type { 1394 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 1395 let r = f.write(fs, &buf[0..len], offset as u64); 1396 guard.update_metadata(); 1397 return r; 1398 } 1399 FATDirEntry::Dir(_) => { 1400 return Err(SystemError::EISDIR); 1401 } 1402 FATDirEntry::UnInit => { 1403 kerror!("FATFS: param: Inode_type uninitialized."); 1404 return Err(SystemError::EROFS); 1405 } 1406 } 1407 } 1408 1409 fn poll(&self) -> Result<PollStatus, SystemError> { 1410 // 加锁 1411 let inode: SpinLockGuard<FATInode> = self.0.lock(); 1412 1413 // 检查当前inode是否为一个文件夹，如果是的话，就返回错误 1414 if inode.metadata.file_type == FileType::Dir { 1415 return Err(SystemError::EISDIR); 1416 } 1417 1418 return Ok(PollStatus::READ | PollStatus::WRITE); 1419 } 1420 1421 fn create( 1422 &self, 1423 name: &str, 1424 file_type: FileType, 1425 _mode: u32, 1426 ) -> Result<Arc<dyn IndexNode>, SystemError> { 1427 // 由于FAT32不支持文件权限的功能，因此忽略mode参数 1428 1429 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1430 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1431 1432 match &mut guard.inode_type { 1433 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1434 return Err(SystemError::ENOTDIR); 1435 } 1436 FATDirEntry::Dir(d) => match file_type { 1437 FileType::File => { 1438 d.create_file(name, fs)?; 1439 return Ok(guard.find(name)?); 1440 } 1441 FileType::Dir => { 1442 d.create_dir(name, fs)?; 1443 return Ok(guard.find(name)?); 1444 } 1445 1446 FileType::SymLink => return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP), 1447 _ => return Err(SystemError::EINVAL), 1448 }, 1449 FATDirEntry::UnInit => { 1450 kerror!("FATFS: param: Inode_type uninitialized."); 1451 return Err(SystemError::EROFS); 1452 } 1453 } 1454 } 1455 1456 fn fs(&self) -> Arc<dyn FileSystem> { 1457 return self.0.lock().fs.upgrade().unwrap(); 1458 } 1459 1460 fn as_any_ref(&self) -> &dyn core::any::Any { 1461 return self; 1462 } 1463 1464 fn metadata(&self) -> Result<Metadata, SystemError> { 1465 return Ok(self.0.lock().metadata.clone()); 1466 } 1467 fn resize(&self, len: usize) -> Result<(), SystemError> { 1468 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1469 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1470 let old_size = guard.metadata.size as usize; 1471 1472 match &mut guard.inode_type { 1473 FATDirEntry::File(file) | FATDirEntry::VolId(file) => { 1474 // 如果新的长度和旧的长度相同，那么就直接返回 1475 if len == old_size { 1476 return Ok(()); 1477 } else if len > old_size { 1478 // 如果新的长度比旧的长度大，那么就在文件末尾添加空白 1479 let mut buf: Vec<u8> = Vec::new(); 1480 let mut remain_size = len - old_size; 1481 let buf_size = remain_size; 1482 // let buf_size = core::cmp::min(remain_size, 512 * 1024); 1483 buf.resize(buf_size, 0); 1484 1485 let mut offset = old_size; 1486 while remain_size > 0 { 1487 let write_size = core::cmp::min(remain_size, buf_size); 1488 file.write(fs, &buf[0..write_size], offset as u64)?; 1489 remain_size -= write_size; 1490 offset += write_size; 1491 } 1492 } else { 1493 file.truncate(fs, len as u64)?; 1494 } 1495 guard.update_metadata(); 1496 return Ok(()); 1497 } 1498 FATDirEntry::Dir(_) => return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP), 1499 FATDirEntry::UnInit => { 1500 kerror!("FATFS: param: Inode_type uninitialized."); 1501 return Err(SystemError::EROFS); 1502 } 1503 } 1504 } 1505 1506 fn list(&self) -> Result<Vec<String>, SystemError> { 1507 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1508 let fatent: &FATDirEntry = &guard.inode_type; 1509 match fatent { 1510 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1511 return Err(SystemError::ENOTDIR); 1512 } 1513 FATDirEntry::Dir(dir) => { 1514 // 获取当前目录下的所有目录项 1515 let mut ret: Vec<String> = Vec::new(); 1516 let dir_iter: FATDirIter = dir.to_iter(guard.fs.upgrade().unwrap()); 1517 for ent in dir_iter { 1518 ret.push(ent.name()); 1519 1520 // ====== 生成inode缓存，存入B树 1521 let name: String = ent.name(); 1522 // kdebug!("name={name}"); 1523 1524 if guard.children.contains_key(&name.to_uppercase()) == false 1525 && name != "." 1526 && name != ".." 1527 { 1528 // 创建新的inode 1529 let entry_inode: Arc<LockedFATInode> = LockedFATInode::new( 1530 guard.fs.upgrade().unwrap(), 1531 guard.self_ref.clone(), 1532 ent, 1533 ); 1534 // 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 1535 guard 1536 .children 1537 .insert(name.to_uppercase(), entry_inode.clone()); 1538 } 1539 } 1540 return Ok(ret); 1541 } 1542 FATDirEntry::UnInit => { 1543 kerror!("FATFS: param: Inode_type uninitialized."); 1544 return Err(SystemError::EROFS); 1545 } 1546 } 1547 } 1548 1549 fn find(&self, name: &str) -> Result<Arc<dyn IndexNode>, SystemError> { 1550 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1551 let target = guard.find(name)?; 1552 return Ok(target); 1553 } 1554 1555 fn open(&self, _data: &mut FilePrivateData, _mode: &FileMode) -> Result<(), SystemError> { 1556 return Ok(()); 1557 } 1558 1559 fn close(&self, _data: &mut FilePrivateData) -> Result<(), SystemError> { 1560 return Ok(()); 1561 } 1562 1563 fn unlink(&self, name: &str) -> Result<(), SystemError> { 1564 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1565 let target: Arc<LockedFATInode> = guard.find(name)?; 1566 // 对目标inode上锁，以防更改 1567 let target_guard: SpinLockGuard<FATInode> = target.0.lock(); 1568 // 先从缓存删除 1569 guard.children.remove(&name.to_uppercase()); 1570 1571 let dir = match &guard.inode_type { 1572 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1573 return Err(SystemError::ENOTDIR); 1574 } 1575 FATDirEntry::Dir(d) => d, 1576 FATDirEntry::UnInit => { 1577 kerror!("FATFS: param: Inode_type uninitialized."); 1578 return Err(SystemError::EROFS); 1579 } 1580 }; 1581 // 检查文件是否存在 1582 dir.check_existence(name, Some(false), guard.fs.upgrade().unwrap())?; 1583 1584 // 再从磁盘删除 1585 let r = dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); 1586 drop(target_guard); 1587 return r; 1588 } 1589 1590 fn rmdir(&self, name: &str) -> Result<(), SystemError> { 1591 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1592 let target: Arc<LockedFATInode> = guard.find(name)?; 1593 // 对目标inode上锁，以防更改 1594 let target_guard: SpinLockGuard<FATInode> = target.0.lock(); 1595 // 先从缓存删除 1596 guard.children.remove(&name.to_uppercase()); 1597 1598 let dir = match &guard.inode_type { 1599 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1600 return Err(SystemError::ENOTDIR); 1601 } 1602 FATDirEntry::Dir(d) => d, 1603 FATDirEntry::UnInit => { 1604 kerror!("FATFS: param: Inode_type uninitialized."); 1605 return Err(SystemError::EROFS); 1606 } 1607 }; 1608 // 检查文件夹是否存在 1609 dir.check_existence(name, Some(true), guard.fs.upgrade().unwrap())?; 1610 1611 // 再从磁盘删除 1612 let r: Result<(), SystemError> = 1613 dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); 1614 if r.is_ok() { 1615 return r; 1616 } else { 1617 let r = r.unwrap_err(); 1618 if r == SystemError::ENOTEMPTY { 1619 // 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 1620 guard.children.insert(name.to_uppercase(), target.clone()); 1621 drop(target_guard); 1622 } 1623 return Err(r); 1624 } 1625 } 1626 1627 fn get_entry_name(&self, ino: InodeId) -> Result<String, SystemError> { 1628 let guard: SpinLockGuard<FATInode> = self.0.lock(); 1629 if guard.metadata.file_type != FileType::Dir { 1630 return Err(SystemError::ENOTDIR); 1631 } 1632 match ino { 1633 0 => { 1634 return Ok(String::from(".")); 1635 } 1636 1 => { 1637 return Ok(String::from("..")); 1638 } 1639 ino => { 1640 // 暴力遍历所有的children，判断inode id是否相同 1641 // TODO: 优化这里，这个地方性能很差！ 1642 let mut key: Vec<String> = guard 1643 .children 1644 .keys() 1645 .filter(|k| guard.children.get(*k).unwrap().metadata().unwrap().inode_id == ino) 1646 .cloned() 1647 .collect(); 1648 1649 match key.len() { 1650 0=>{return Err(SystemError::ENOENT);} 1651 1=>{return Ok(key.remove(0));} 1652 _ => 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) 1653 } 1654 } 1655 } 1656 } 1657 } 1658 1659 impl Default for FATFsInfo { 1660 fn default() -> Self { 1661 return FATFsInfo { 1662 lead_sig: FATFsInfo::LEAD_SIG, 1663 struc_sig: FATFsInfo::STRUC_SIG, 1664 free_count: 0xFFFFFFFF, 1665 next_free: RESERVED_CLUSTERS, 1666 trail_sig: FATFsInfo::TRAIL_SIG, 1667 dirty: false, 1668 offset: None, 1669 }; 1670 } 1671 } 1672 1673 impl Cluster { 1674 pub fn new(cluster: u64) -> Self { 1675 return Cluster { 1676 cluster_num: cluster, 1677 parent_cluster: 0, 1678 }; 1679 } 1680 } 1681 1682 /// @brief 用于迭代FAT表的内容的簇迭代器对象 1683 #[derive(Debug)] 1684 struct ClusterIter<'a> { 1685 /// 迭代器的next要返回的簇 1686 current_cluster: Option<Cluster>, 1687 /// 属于的文件系统 1688 fs: &'a FATFileSystem, 1689 } 1690 1691 impl<'a> Iterator for ClusterIter<'a> { 1692 type Item = Cluster; 1693 1694 fn next(&mut self) -> Option<Self::Item> { 1695 // 当前要返回的簇 1696 let ret: Option<Cluster> = self.current_cluster; 1697 1698 // 获得下一个要返回簇 1699 let new: Option<Cluster> = match self.current_cluster { 1700 Some(c) => { 1701 let entry: Option<FATEntry> = self.fs.get_fat_entry(c).ok(); 1702 match entry { 1703 Some(FATEntry::Next(c)) => Some(c), 1704 _ => None, 1705 } 1706 } 1707 _ => None, 1708 }; 1709 1710 self.current_cluster = new; 1711 return ret; 1712 } 1713 } 1714