1 #![allow(dead_code)] 2 use core::intrinsics::unlikely; 3 use core::{any::Any, fmt::Debug}; 4 5 use alloc::{ 6 collections::BTreeMap, 7 string::String, 8 sync::{Arc, Weak}, 9 vec::Vec, 10 }; 11 12 use crate::filesystem::vfs::SpecialNodeData; 13 use crate::ipc::pipe::LockedPipeInode; 14 use crate::{ 15 driver::base::block::{block_device::LBA_SIZE, disk_info::Partition, SeekFrom}, 16 filesystem::vfs::{ 17 core::generate_inode_id, 18 file::{FileMode, FilePrivateData}, 19 syscall::ModeType, 20 FileSystem, FileType, IndexNode, InodeId, Metadata, 21 }, 22 kerror, 23 libs::{ 24 spinlock::{SpinLock, SpinLockGuard}, 25 vec_cursor::VecCursor, 26 }, 27 syscall::SystemError, 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 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 58 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] 88 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 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 } 131 132 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 { 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: 0, 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 { 238 fn root_inode(&self) -> Arc<dyn crate::filesystem::vfs::IndexNode> { 239 return self.root_inode.clone(); 240 } 241 242 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 248 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; 260 261 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: 0, 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] 351 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 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 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 511 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 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) 543 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 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 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 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 638 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） 660 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 667 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 683 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 700 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] 713 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] 721 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] 727 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] 733 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] 739 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 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 753 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 761 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] 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] 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 pub fn is_shut_bit_ok(&mut self) -> Result<bool, SystemError> { 788 match self.bpb.fat_type { 789 FATType::FAT32(_) => { 790 // 对于FAT32, error bit位于第一个扇区的第8字节。 791 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0800_0000; 792 return Ok(bit > 0); 793 } 794 FATType::FAT16(_) => { 795 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x8000; 796 return Ok(bit > 0); 797 } 798 _ => return Ok(true), 799 } 800 } 801 802 /// @brief 判断FAT文件系统的hard error bit是否正常。 803 /// 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 804 /// 卷上的某些扇区可能已损坏。 805 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 806 /// 807 /// @return Ok(true) 正常 808 /// @return Ok(false) 不正常 809 /// @return Err(SystemError) 在判断时发生错误 810 pub fn is_hard_error_bit_ok(&mut self) -> Result<bool, SystemError> { 811 match self.bpb.fat_type { 812 FATType::FAT32(_) => { 813 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0400_0000; 814 return Ok(bit > 0); 815 } 816 FATType::FAT16(_) => { 817 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x4000; 818 return Ok(bit > 0); 819 } 820 _ => return Ok(true), 821 } 822 } 823 824 /// @brief 设置文件系统的shut bit为正常状态 825 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 826 /// 827 /// @return Ok(()) 设置成功 828 /// @return Err(SystemError) 在设置过程中，出现错误 829 pub fn set_shut_bit_ok(&mut self) -> Result<(), SystemError> { 830 match self.bpb.fat_type { 831 FATType::FAT32(_) => { 832 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0800_0000; 833 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 834 835 return Ok(()); 836 } 837 838 FATType::FAT16(_) => { 839 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x8000; 840 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 841 return Ok(()); 842 } 843 _ => return Ok(()), 844 } 845 } 846 847 /// @brief 设置文件系统的hard error bit为正常状态 848 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 849 /// 850 /// @return Ok(()) 设置成功 851 /// @return Err(SystemError) 在设置过程中，出现错误 852 pub fn set_hard_error_bit_ok(&mut self) -> Result<(), SystemError> { 853 match self.bpb.fat_type { 854 FATType::FAT32(_) => { 855 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0400_0000; 856 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 857 return Ok(()); 858 } 859 860 FATType::FAT16(_) => { 861 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x4000; 862 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 863 return Ok(()); 864 } 865 _ => return Ok(()), 866 } 867 } 868 869 /// @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 870 pub fn umount(&mut self) -> Result<(), SystemError> { 871 self.fs_info.0.lock().flush(&self.partition)?; 872 873 self.set_shut_bit_ok()?; 874 875 self.set_hard_error_bit_ok()?; 876 877 self.partition.disk().sync()?; 878 879 return Ok(()); 880 } 881 882 /// @brief 获取文件系统的最大簇号 883 pub fn max_cluster_number(&self) -> Cluster { 884 match self.bpb.fat_type { 885 FATType::FAT32(s) => { 886 // FAT32 887 888 // 数据扇区数量（总扇区数-保留扇区-FAT占用的扇区） 889 let data_sec: u64 = self.bpb.total_sectors_32 as u64 890 - (self.bpb.rsvd_sec_cnt as u64 891 + self.bpb.num_fats as u64 * s.fat_size_32 as u64); 892 893 // 数据区的簇数量 894 let total_clusters: u64 = data_sec / self.bpb.sector_per_cluster as u64; 895 896 // 返回最大的簇号 897 return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); 898 } 899 900 _ => { 901 // FAT12 / FAT16 902 let root_dir_sectors: u64 = (((self.bpb.root_entries_cnt as u64) * 32) 903 + self.bpb.bytes_per_sector as u64 904 - 1) 905 / self.bpb.bytes_per_sector as u64; 906 // 数据区扇区数 907 let data_sec: u64 = self.bpb.total_sectors_16 as u64 908 - (self.bpb.rsvd_sec_cnt as u64 909 + (self.bpb.num_fats as u64 * self.bpb.fat_size_16 as u64) 910 + root_dir_sectors); 911 let total_clusters = data_sec / self.bpb.sector_per_cluster as u64; 912 return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); 913 } 914 } 915 } 916 917 /// @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 918 /// 919 /// @param start_cluster 起始簇号 920 /// @param end_cluster 终止簇号（不包含） 921 /// 922 /// @return Ok(Cluster) 寻找到的空闲簇 923 /// @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. 924 pub fn get_free_cluster( 925 &self, 926 start_cluster: Cluster, 927 end_cluster: Cluster, 928 ) -> Result<Cluster, SystemError> { 929 let max_cluster: Cluster = self.max_cluster_number(); 930 let mut cluster: u64 = start_cluster.cluster_num; 931 932 let fat_type: FATType = self.bpb.fat_type; 933 let fat_start_sector: u64 = self.fat_start_sector(); 934 let bytes_per_sec: u64 = self.bpb.bytes_per_sector as u64; 935 936 match fat_type { 937 FATType::FAT12(_) => { 938 let part_bytes_offset: u64 = 939 fat_type.get_fat_bytes_offset(start_cluster, fat_start_sector, bytes_per_sec); 940 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 941 942 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 943 944 // 由于FAT12的FAT表不大于6K，因此直接读取6K 945 let num_lba = (6 * 1024) / LBA_SIZE; 946 let mut v: Vec<u8> = Vec::new(); 947 v.resize(num_lba * LBA_SIZE, 0); 948 self.partition.disk().read_at(lba, num_lba, &mut v)?; 949 950 let mut cursor: VecCursor = VecCursor::new(v); 951 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 952 953 let mut packed_val: u16 = cursor.read_u16()?; 954 loop { 955 let val = if (cluster & 0x1) > 0 { 956 packed_val >> 4 957 } else { 958 packed_val & 0x0fff 959 }; 960 if val == 0 { 961 return Ok(Cluster::new(cluster as u64)); 962 } 963 964 cluster += 1; 965 966 // 磁盘无剩余空间，或者簇号达到给定的最大值 967 if cluster == end_cluster.cluster_num || cluster == max_cluster.cluster_num { 968 return Err(SystemError::ENOSPC); 969 } 970 971 packed_val = match cluster & 1 { 972 0 => cursor.read_u16()?, 973 _ => { 974 let next_byte = cursor.read_u8()? as u16; 975 (packed_val >> 8) | (next_byte << 8) 976 } 977 }; 978 } 979 } 980 FATType::FAT16(_) => { 981 // todo: 优化这里，减少读取磁盘的次数。 982 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { 983 let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( 984 Cluster::new(cluster), 985 fat_start_sector, 986 bytes_per_sec, 987 ); 988 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 989 990 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 991 992 let mut v: Vec<u8> = Vec::new(); 993 v.resize(self.lba_per_sector() * LBA_SIZE, 0); 994 self.partition 995 .disk() 996 .read_at(lba, self.lba_per_sector(), &mut v)?; 997 998 let mut cursor: VecCursor = VecCursor::new(v); 999 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1000 1001 let val = cursor.read_u16()?; 1002 // 找到空闲簇 1003 if val == 0 { 1004 return Ok(Cluster::new(val as u64)); 1005 } 1006 cluster += 1; 1007 } 1008 1009 // 磁盘无剩余空间，或者簇号达到给定的最大值 1010 return Err(SystemError::ENOSPC); 1011 } 1012 FATType::FAT32(_) => { 1013 // todo: 优化这里，减少读取磁盘的次数。 1014 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { 1015 let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( 1016 Cluster::new(cluster), 1017 fat_start_sector, 1018 bytes_per_sec, 1019 ); 1020 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 1021 1022 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 1023 1024 let mut v: Vec<u8> = Vec::new(); 1025 v.resize(self.lba_per_sector() * LBA_SIZE, 0); 1026 self.partition 1027 .disk() 1028 .read_at(lba, self.lba_per_sector(), &mut v)?; 1029 1030 let mut cursor: VecCursor = VecCursor::new(v); 1031 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1032 1033 let val = cursor.read_u32()? & 0x0fffffff; 1034 1035 if val == 0 { 1036 return Ok(Cluster::new(cluster)); 1037 } 1038 cluster += 1; 1039 } 1040 1041 // 磁盘无剩余空间，或者簇号达到给定的最大值 1042 return Err(SystemError::ENOSPC); 1043 } 1044 } 1045 } 1046 1047 /// @brief 在FAT表中，设置指定的簇的信息。 1048 /// 1049 /// @param cluster 目标簇 1050 /// @param fat_entry 这个簇在FAT表中，存储的信息（下一个簇的簇号） 1051 pub fn set_entry(&self, cluster: Cluster, fat_entry: FATEntry) -> Result<(), SystemError> { 1052 // fat表项在分区上的字节偏移量 1053 let fat_part_bytes_offset: u64 = self.bpb.fat_type.get_fat_bytes_offset( 1054 cluster, 1055 self.fat_start_sector(), 1056 self.bpb.bytes_per_sector as u64, 1057 ); 1058 1059 match self.bpb.fat_type { 1060 FATType::FAT12(_) => { 1061 // 计算要写入的值 1062 let raw_val: u16 = match fat_entry { 1063 FATEntry::Unused => 0, 1064 FATEntry::Bad => 0xff7, 1065 FATEntry::EndOfChain => 0xfff, 1066 FATEntry::Next(c) => c.cluster_num as u16, 1067 }; 1068 1069 let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); 1070 1071 let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); 1072 1073 let mut v: Vec<u8> = Vec::new(); 1074 v.resize(LBA_SIZE, 0); 1075 self.partition.disk().read_at(lba, 1, &mut v)?; 1076 1077 let mut cursor: VecCursor = VecCursor::new(v); 1078 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1079 1080 let old_val: u16 = cursor.read_u16()?; 1081 let new_val: u16 = if (cluster.cluster_num & 0x1) > 0 { 1082 (old_val & 0x000f) | (raw_val << 4) 1083 } else { 1084 (old_val & 0xf000) | raw_val 1085 }; 1086 1087 // 写回数据到磁盘上 1088 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1089 cursor.write_u16(new_val)?; 1090 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1091 return Ok(()); 1092 } 1093 FATType::FAT16(_) => { 1094 // 计算要写入的值 1095 let raw_val: u16 = match fat_entry { 1096 FATEntry::Unused => 0, 1097 FATEntry::Bad => 0xfff7, 1098 FATEntry::EndOfChain => 0xfdff, 1099 FATEntry::Next(c) => c.cluster_num as u16, 1100 }; 1101 1102 let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); 1103 1104 let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); 1105 1106 let mut v: Vec<u8> = Vec::new(); 1107 v.resize(LBA_SIZE, 0); 1108 self.partition.disk().read_at(lba, 1, &mut v)?; 1109 1110 let mut cursor: VecCursor = VecCursor::new(v); 1111 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1112 1113 cursor.write_u16(raw_val)?; 1114 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1115 1116 return Ok(()); 1117 } 1118 FATType::FAT32(_) => { 1119 let fat_size: u64 = self.fat_size(); 1120 let bound: u64 = if self.mirroring_enabled() { 1121 1 1122 } else { 1123 self.bpb.num_fats as u64 1124 }; 1125 // kdebug!("set entry, bound={bound}, fat_size={fat_size}"); 1126 for i in 0..bound { 1127 // 当前操作的FAT表在磁盘上的字节偏移量 1128 let f_offset: u64 = fat_part_bytes_offset + i * fat_size; 1129 let in_block_offset: u64 = self.get_in_block_offset(f_offset); 1130 let lba = self.get_lba_from_offset(self.bytes_to_sector(f_offset)); 1131 1132 // kdebug!("set entry, lba={lba}, in_block_offset={in_block_offset}"); 1133 let mut v: Vec<u8> = Vec::new(); 1134 v.resize(LBA_SIZE, 0); 1135 self.partition.disk().read_at(lba, 1, &mut v)?; 1136 1137 let mut cursor: VecCursor = VecCursor::new(v); 1138 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1139 1140 // FAT32的高4位保留 1141 let old_bits = cursor.read_u32()? & 0xf0000000; 1142 1143 if fat_entry == FATEntry::Unused 1144 && cluster.cluster_num >= 0x0ffffff7 1145 && cluster.cluster_num <= 0x0fffffff 1146 { 1147 kerror!( 1148 "FAT32: Reserved Cluster {:?} cannot be marked as free", 1149 cluster 1150 ); 1151 return Err(SystemError::EPERM); 1152 } 1153 1154 // 计算要写入的值 1155 let mut raw_val: u32 = match fat_entry { 1156 FATEntry::Unused => 0, 1157 FATEntry::Bad => 0x0FFFFFF7, 1158 FATEntry::EndOfChain => 0x0FFFFFFF, 1159 FATEntry::Next(c) => c.cluster_num as u32, 1160 }; 1161 1162 // 恢复保留位 1163 raw_val |= old_bits; 1164 1165 // kdebug!("sent entry, raw_val={raw_val}"); 1166 1167 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1168 cursor.write_u32(raw_val)?; 1169 1170 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1171 } 1172 1173 return Ok(()); 1174 } 1175 } 1176 } 1177 1178 /// @brief 清空指定的簇 1179 /// 1180 /// @param cluster 要被清空的簇 1181 pub fn zero_cluster(&self, cluster: Cluster) -> Result<(), SystemError> { 1182 // 准备数据，用于写入 1183 let zeros: Vec<u8> = vec![0u8; self.bytes_per_cluster() as usize]; 1184 let offset: usize = self.cluster_bytes_offset(cluster) as usize; 1185 self.partition 1186 .disk() 1187 .write_at_bytes(offset, zeros.len(), zeros.as_slice())?; 1188 return Ok(()); 1189 } 1190 } 1191 1192 impl Drop for FATFileSystem { 1193 fn drop(&mut self) { 1194 let r = self.umount(); 1195 if r.is_err() { 1196 kerror!( 1197 "Umount FAT filesystem failed: errno={:?}, FS detail:{self:?}", 1198 r.unwrap_err() 1199 ); 1200 } 1201 } 1202 } 1203 1204 impl FATFsInfo { 1205 const LEAD_SIG: u32 = 0x41615252; 1206 const STRUC_SIG: u32 = 0x61417272; 1207 const TRAIL_SIG: u32 = 0xAA550000; 1208 const FS_INFO_SIZE: u64 = 512; 1209 1210 /// @brief 从磁盘上读取FAT文件系统的FSInfo结构体 1211 /// 1212 /// @param partition 磁盘分区 1213 /// @param in_disk_fs_info_offset FSInfo扇区在磁盘内的字节偏移量（单位：字节） 1214 /// @param bytes_per_sec 每扇区字节数 1215 pub fn new( 1216 partition: Arc<Partition>, 1217 in_disk_fs_info_offset: u64, 1218 bytes_per_sec: usize, 1219 ) -> Result<Self, SystemError> { 1220 let mut v = Vec::<u8>::new(); 1221 v.resize(bytes_per_sec, 0); 1222 1223 // 计算fs_info扇区在磁盘上的字节偏移量，从磁盘读取数据 1224 partition 1225 .disk() 1226 .read_at(in_disk_fs_info_offset as usize / LBA_SIZE, 1, &mut v)?; 1227 let mut cursor = VecCursor::new(v); 1228 1229 let mut fsinfo = FATFsInfo::default(); 1230 1231 fsinfo.lead_sig = cursor.read_u32()?; 1232 cursor.seek(SeekFrom::SeekCurrent(480))?; 1233 fsinfo.struc_sig = cursor.read_u32()?; 1234 fsinfo.free_count = cursor.read_u32()?; 1235 fsinfo.next_free = cursor.read_u32()?; 1236 1237 cursor.seek(SeekFrom::SeekCurrent(12))?; 1238 1239 fsinfo.trail_sig = cursor.read_u32()?; 1240 fsinfo.dirty = false; 1241 fsinfo.offset = Some(in_disk_fs_info_offset); 1242 1243 if fsinfo.is_valid() { 1244 return Ok(fsinfo); 1245 } else { 1246 kerror!("Error occurred while parsing FATFsInfo."); 1247 return Err(SystemError::EINVAL); 1248 } 1249 } 1250 1251 /// @brief 判断是否为正确的FsInfo结构体 1252 fn is_valid(&self) -> bool { 1253 self.lead_sig == Self::LEAD_SIG 1254 && self.struc_sig == Self::STRUC_SIG 1255 && self.trail_sig == Self::TRAIL_SIG 1256 } 1257 1258 /// @brief 根据fsinfo的信息，计算当前总的空闲簇数量 1259 /// 1260 /// @param 当前文件系统的最大簇号 1261 pub fn count_free_cluster(&self, max_cluster: Cluster) -> Option<u64> { 1262 let count_clusters = max_cluster.cluster_num - RESERVED_CLUSTERS as u64 + 1; 1263 // 信息不合理，当前的FsInfo中存储的free count大于计算出来的值 1264 if self.free_count as u64 > count_clusters { 1265 return None; 1266 } else { 1267 match self.free_count { 1268 // free count字段不可用 1269 0xffffffff => return None, 1270 // 返回FsInfo中存储的数据 1271 n => return Some(n as u64), 1272 } 1273 } 1274 } 1275 1276 /// @brief 更新FsInfo中的“空闲簇统计信息“为new_count 1277 /// 1278 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 1279 pub fn update_free_count_abs(&mut self, new_count: u32) { 1280 self.free_count = new_count; 1281 } 1282 1283 /// @brief 更新FsInfo中的“空闲簇统计信息“，把它加上delta. 1284 /// 1285 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 1286 pub fn update_free_count_delta(&mut self, delta: i32) { 1287 self.free_count = (self.free_count as i32 + delta) as u32; 1288 } 1289 1290 /// @brief 更新FsInfo中的“第一个空闲簇统计信息“为next_free. 1291 /// 1292 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 1293 pub fn update_next_free(&mut self, next_free: u32) { 1294 // 这个值是参考量，不一定要准确，仅供加速查找 1295 self.next_free = next_free; 1296 } 1297 1298 /// @brief 获取fs info 记载的第一个空闲簇。（不一定准确，仅供参考） 1299 pub fn next_free(&self) -> Option<u64> { 1300 match self.next_free { 1301 0xffffffff => return None, 1302 0 | 1 => return None, 1303 n => return Some(n as u64), 1304 }; 1305 } 1306 1307 /// @brief 把fs info刷入磁盘 1308 /// 1309 /// @param partition fs info所在的分区 1310 pub fn flush(&self, partition: &Arc<Partition>) -> Result<(), SystemError> { 1311 if let Some(off) = self.offset { 1312 let in_block_offset = off % LBA_SIZE as u64; 1313 1314 let lba = off as usize / LBA_SIZE; 1315 1316 let mut v: Vec<u8> = Vec::new(); 1317 v.resize(LBA_SIZE, 0); 1318 partition.disk().read_at(lba, 1, &mut v)?; 1319 1320 let mut cursor: VecCursor = VecCursor::new(v); 1321 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1322 1323 cursor.write_u32(self.lead_sig)?; 1324 cursor.seek(SeekFrom::SeekCurrent(480))?; 1325 cursor.write_u32(self.struc_sig)?; 1326 cursor.write_u32(self.free_count)?; 1327 cursor.write_u32(self.next_free)?; 1328 cursor.seek(SeekFrom::SeekCurrent(12))?; 1329 cursor.write_u32(self.trail_sig)?; 1330 1331 partition.disk().write_at(lba, 1, cursor.as_slice())?; 1332 } 1333 return Ok(()); 1334 } 1335 1336 /// @brief 读取磁盘上的Fs Info扇区，将里面的内容更新到结构体中 1337 /// 1338 /// @param partition fs info所在的分区 1339 pub fn update(&mut self, partition: Arc<Partition>) -> Result<(), SystemError> { 1340 if let Some(off) = self.offset { 1341 let in_block_offset = off % LBA_SIZE as u64; 1342 1343 let lba = off as usize / LBA_SIZE; 1344 1345 let mut v: Vec<u8> = Vec::new(); 1346 v.resize(LBA_SIZE, 0); 1347 partition.disk().read_at(lba, 1, &mut v)?; 1348 let mut cursor: VecCursor = VecCursor::new(v); 1349 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1350 self.lead_sig = cursor.read_u32()?; 1351 1352 cursor.seek(SeekFrom::SeekCurrent(480))?; 1353 self.struc_sig = cursor.read_u32()?; 1354 self.free_count = cursor.read_u32()?; 1355 self.next_free = cursor.read_u32()?; 1356 cursor.seek(SeekFrom::SeekCurrent(12))?; 1357 self.trail_sig = cursor.read_u32()?; 1358 } 1359 return Ok(()); 1360 } 1361 } 1362 1363 impl IndexNode for LockedFATInode { 1364 fn read_at( 1365 &self, 1366 offset: usize, 1367 len: usize, 1368 buf: &mut [u8], 1369 _data: &mut FilePrivateData, 1370 ) -> Result<usize, SystemError> { 1371 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1372 match &guard.inode_type { 1373 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 1374 let r = f.read( 1375 &guard.fs.upgrade().unwrap(), 1376 &mut buf[0..len], 1377 offset as u64, 1378 ); 1379 guard.update_metadata(); 1380 return r; 1381 } 1382 FATDirEntry::Dir(_) => { 1383 return Err(SystemError::EISDIR); 1384 } 1385 FATDirEntry::UnInit => { 1386 kerror!("FATFS: param: Inode_type uninitialized."); 1387 return Err(SystemError::EROFS); 1388 } 1389 } 1390 } 1391 1392 fn write_at( 1393 &self, 1394 offset: usize, 1395 len: usize, 1396 buf: &[u8], 1397 _data: &mut FilePrivateData, 1398 ) -> Result<usize, SystemError> { 1399 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1400 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1401 1402 match &mut guard.inode_type { 1403 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 1404 let r = f.write(fs, &buf[0..len], offset as u64); 1405 guard.update_metadata(); 1406 return r; 1407 } 1408 FATDirEntry::Dir(_) => { 1409 return Err(SystemError::EISDIR); 1410 } 1411 FATDirEntry::UnInit => { 1412 kerror!("FATFS: param: Inode_type uninitialized."); 1413 return Err(SystemError::EROFS); 1414 } 1415 } 1416 } 1417 1418 fn create( 1419 &self, 1420 name: &str, 1421 file_type: FileType, 1422 _mode: ModeType, 1423 ) -> Result<Arc<dyn IndexNode>, SystemError> { 1424 // 由于FAT32不支持文件权限的功能，因此忽略mode参数 1425 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1426 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1427 1428 match &mut guard.inode_type { 1429 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1430 return Err(SystemError::ENOTDIR); 1431 } 1432 FATDirEntry::Dir(d) => match file_type { 1433 FileType::File => { 1434 d.create_file(name, fs)?; 1435 return Ok(guard.find(name)?); 1436 } 1437 FileType::Dir => { 1438 d.create_dir(name, fs)?; 1439 return Ok(guard.find(name)?); 1440 } 1441 1442 FileType::SymLink => return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP), 1443 _ => return Err(SystemError::EINVAL), 1444 }, 1445 FATDirEntry::UnInit => { 1446 kerror!("FATFS: param: Inode_type uninitialized."); 1447 return Err(SystemError::EROFS); 1448 } 1449 } 1450 } 1451 1452 fn fs(&self) -> Arc<dyn FileSystem> { 1453 return self.0.lock().fs.upgrade().unwrap(); 1454 } 1455 1456 fn as_any_ref(&self) -> &dyn core::any::Any { 1457 return self; 1458 } 1459 1460 fn metadata(&self) -> Result<Metadata, SystemError> { 1461 return Ok(self.0.lock().metadata.clone()); 1462 } 1463 fn resize(&self, len: usize) -> Result<(), SystemError> { 1464 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1465 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1466 let old_size = guard.metadata.size as usize; 1467 1468 match &mut guard.inode_type { 1469 FATDirEntry::File(file) | FATDirEntry::VolId(file) => { 1470 // 如果新的长度和旧的长度相同，那么就直接返回 1471 if len == old_size { 1472 return Ok(()); 1473 } else if len > old_size { 1474 // 如果新的长度比旧的长度大，那么就在文件末尾添加空白 1475 let mut buf: Vec<u8> = Vec::new(); 1476 let mut remain_size = len - old_size; 1477 let buf_size = remain_size; 1478 // let buf_size = core::cmp::min(remain_size, 512 * 1024); 1479 buf.resize(buf_size, 0); 1480 1481 let mut offset = old_size; 1482 while remain_size > 0 { 1483 let write_size = core::cmp::min(remain_size, buf_size); 1484 file.write(fs, &buf[0..write_size], offset as u64)?; 1485 remain_size -= write_size; 1486 offset += write_size; 1487 } 1488 } else { 1489 file.truncate(fs, len as u64)?; 1490 } 1491 guard.update_metadata(); 1492 return Ok(()); 1493 } 1494 FATDirEntry::Dir(_) => return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP), 1495 FATDirEntry::UnInit => { 1496 kerror!("FATFS: param: Inode_type uninitialized."); 1497 return Err(SystemError::EROFS); 1498 } 1499 } 1500 } 1501 1502 fn truncate(&self, len: usize) -> Result<(), SystemError> { 1503 let guard: SpinLockGuard<FATInode> = self.0.lock(); 1504 let old_size = guard.metadata.size as usize; 1505 if len < old_size { 1506 drop(guard); 1507 self.resize(len) 1508 } else { 1509 Ok(()) 1510 } 1511 } 1512 1513 fn list(&self) -> Result<Vec<String>, SystemError> { 1514 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1515 let fatent: &FATDirEntry = &guard.inode_type; 1516 match fatent { 1517 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1518 return Err(SystemError::ENOTDIR); 1519 } 1520 FATDirEntry::Dir(dir) => { 1521 // 获取当前目录下的所有目录项 1522 let mut ret: Vec<String> = Vec::new(); 1523 let dir_iter: FATDirIter = dir.to_iter(guard.fs.upgrade().unwrap()); 1524 for ent in dir_iter { 1525 ret.push(ent.name()); 1526 1527 // ====== 生成inode缓存，存入B树 1528 let name: String = ent.name(); 1529 // kdebug!("name={name}"); 1530 1531 if guard.children.contains_key(&name.to_uppercase()) == false 1532 && name != "." 1533 && name != ".." 1534 { 1535 // 创建新的inode 1536 let entry_inode: Arc<LockedFATInode> = LockedFATInode::new( 1537 guard.fs.upgrade().unwrap(), 1538 guard.self_ref.clone(), 1539 ent, 1540 ); 1541 // 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 1542 guard 1543 .children 1544 .insert(name.to_uppercase(), entry_inode.clone()); 1545 } 1546 } 1547 return Ok(ret); 1548 } 1549 FATDirEntry::UnInit => { 1550 kerror!("FATFS: param: Inode_type uninitialized."); 1551 return Err(SystemError::EROFS); 1552 } 1553 } 1554 } 1555 1556 fn find(&self, name: &str) -> Result<Arc<dyn IndexNode>, SystemError> { 1557 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1558 let target = guard.find(name)?; 1559 return Ok(target); 1560 } 1561 1562 fn open(&self, _data: &mut FilePrivateData, _mode: &FileMode) -> Result<(), SystemError> { 1563 return Ok(()); 1564 } 1565 1566 fn close(&self, _data: &mut FilePrivateData) -> Result<(), SystemError> { 1567 return Ok(()); 1568 } 1569 1570 fn unlink(&self, name: &str) -> Result<(), SystemError> { 1571 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1572 let target: Arc<LockedFATInode> = guard.find(name)?; 1573 // 对目标inode上锁，以防更改 1574 let target_guard: SpinLockGuard<FATInode> = target.0.lock(); 1575 // 先从缓存删除 1576 let nod = guard.children.remove(&name.to_uppercase()); 1577 1578 // 若删除缓存中为管道的文件，则不需要再到磁盘删除 1579 if let Some(_) = nod { 1580 let file_type = target_guard.metadata.file_type; 1581 if file_type == FileType::Pipe { 1582 return Ok(()); 1583 } 1584 } 1585 1586 let dir = match &guard.inode_type { 1587 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1588 return Err(SystemError::ENOTDIR); 1589 } 1590 FATDirEntry::Dir(d) => d, 1591 FATDirEntry::UnInit => { 1592 kerror!("FATFS: param: Inode_type uninitialized."); 1593 return Err(SystemError::EROFS); 1594 } 1595 }; 1596 // 检查文件是否存在 1597 dir.check_existence(name, Some(false), guard.fs.upgrade().unwrap())?; 1598 1599 // 再从磁盘删除 1600 let r = dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); 1601 drop(target_guard); 1602 return r; 1603 } 1604 1605 fn rmdir(&self, name: &str) -> Result<(), SystemError> { 1606 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1607 let target: Arc<LockedFATInode> = guard.find(name)?; 1608 // 对目标inode上锁，以防更改 1609 let target_guard: SpinLockGuard<FATInode> = target.0.lock(); 1610 // 先从缓存删除 1611 guard.children.remove(&name.to_uppercase()); 1612 1613 let dir = match &guard.inode_type { 1614 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1615 return Err(SystemError::ENOTDIR); 1616 } 1617 FATDirEntry::Dir(d) => d, 1618 FATDirEntry::UnInit => { 1619 kerror!("FATFS: param: Inode_type uninitialized."); 1620 return Err(SystemError::EROFS); 1621 } 1622 }; 1623 // 检查文件夹是否存在 1624 dir.check_existence(name, Some(true), guard.fs.upgrade().unwrap())?; 1625 1626 // 再从磁盘删除 1627 let r: Result<(), SystemError> = 1628 dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); 1629 if r.is_ok() { 1630 return r; 1631 } else { 1632 let r = r.unwrap_err(); 1633 if r == SystemError::ENOTEMPTY { 1634 // 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 1635 guard.children.insert(name.to_uppercase(), target.clone()); 1636 drop(target_guard); 1637 } 1638 return Err(r); 1639 } 1640 } 1641 1642 fn get_entry_name(&self, ino: InodeId) -> Result<String, SystemError> { 1643 let guard: SpinLockGuard<FATInode> = self.0.lock(); 1644 if guard.metadata.file_type != FileType::Dir { 1645 return Err(SystemError::ENOTDIR); 1646 } 1647 match ino.into() { 1648 0 => { 1649 return Ok(String::from(".")); 1650 } 1651 1 => { 1652 return Ok(String::from("..")); 1653 } 1654 ino => { 1655 // 暴力遍历所有的children，判断inode id是否相同 1656 // TODO: 优化这里，这个地方性能很差！ 1657 let mut key: Vec<String> = guard 1658 .children 1659 .keys() 1660 .filter(|k| { 1661 guard 1662 .children 1663 .get(*k) 1664 .unwrap() 1665 .metadata() 1666 .unwrap() 1667 .inode_id 1668 .into() 1669 == ino 1670 }) 1671 .cloned() 1672 .collect(); 1673 1674 match key.len() { 1675 0=>{return Err(SystemError::ENOENT);} 1676 1=>{return Ok(key.remove(0));} 1677 _ => 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) 1678 } 1679 } 1680 } 1681 } 1682 1683 fn mknod( 1684 &self, 1685 filename: &str, 1686 mode: ModeType, 1687 _dev_t: crate::driver::base::device::DeviceNumber, 1688 ) -> Result<Arc<dyn IndexNode>, SystemError> { 1689 let mut inode = self.0.lock(); 1690 if inode.metadata.file_type != FileType::Dir { 1691 return Err(SystemError::ENOTDIR); 1692 } 1693 1694 // 判断需要创建的类型 1695 if unlikely(mode.contains(ModeType::S_IFREG)) { 1696 // 普通文件 1697 return Ok(self.create(filename, FileType::File, mode)?); 1698 } 1699 1700 let nod = LockedFATInode::new( 1701 inode.fs.upgrade().unwrap(), 1702 inode.self_ref.clone(), 1703 FATDirEntry::File(FATFile::default()), 1704 ); 1705 1706 if mode.contains(ModeType::S_IFIFO) { 1707 nod.0.lock().metadata.file_type = FileType::Pipe; 1708 // 创建pipe文件 1709 let pipe_inode = LockedPipeInode::new(); 1710 // 设置special_node 1711 nod.0.lock().special_node = Some(SpecialNodeData::Pipe(pipe_inode)); 1712 } else if mode.contains(ModeType::S_IFBLK) { 1713 nod.0.lock().metadata.file_type = FileType::BlockDevice; 1714 unimplemented!() 1715 } else if mode.contains(ModeType::S_IFCHR) { 1716 nod.0.lock().metadata.file_type = FileType::CharDevice; 1717 unimplemented!() 1718 } else { 1719 return Err(SystemError::EINVAL); 1720 } 1721 1722 inode 1723 .children 1724 .insert(String::from(filename).to_uppercase(), nod.clone()); 1725 Ok(nod) 1726 } 1727 1728 fn special_node(&self) -> Option<SpecialNodeData> { 1729 self.0.lock().special_node.clone() 1730 } 1731 } 1732 1733 impl Default for FATFsInfo { 1734 fn default() -> Self { 1735 return FATFsInfo { 1736 lead_sig: FATFsInfo::LEAD_SIG, 1737 struc_sig: FATFsInfo::STRUC_SIG, 1738 free_count: 0xFFFFFFFF, 1739 next_free: RESERVED_CLUSTERS, 1740 trail_sig: FATFsInfo::TRAIL_SIG, 1741 dirty: false, 1742 offset: None, 1743 }; 1744 } 1745 } 1746 1747 impl Cluster { 1748 pub fn new(cluster: u64) -> Self { 1749 return Cluster { 1750 cluster_num: cluster, 1751 parent_cluster: 0, 1752 }; 1753 } 1754 } 1755 1756 /// @brief 用于迭代FAT表的内容的簇迭代器对象 1757 #[derive(Debug)] 1758 struct ClusterIter<'a> { 1759 /// 迭代器的next要返回的簇 1760 current_cluster: Option<Cluster>, 1761 /// 属于的文件系统 1762 fs: &'a FATFileSystem, 1763 } 1764 1765 impl<'a> Iterator for ClusterIter<'a> { 1766 type Item = Cluster; 1767 1768 fn next(&mut self) -> Option<Self::Item> { 1769 // 当前要返回的簇 1770 let ret: Option<Cluster> = self.current_cluster; 1771 1772 // 获得下一个要返回簇 1773 let new: Option<Cluster> = match self.current_cluster { 1774 Some(c) => { 1775 let entry: Option<FATEntry> = self.fs.get_fat_entry(c).ok(); 1776 match entry { 1777 Some(FATEntry::Next(c)) => Some(c), 1778 _ => None, 1779 } 1780 } 1781 _ => None, 1782 }; 1783 1784 self.current_cluster = new; 1785 return ret; 1786 } 1787 } 1788