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::{ 13 core::generate_inode_id, 14 file::{FileMode, FilePrivateData}, 15 FileSystem, FileType, IndexNode, InodeId, Metadata, PollStatus, 16 }, 17 io::{device::LBA_SIZE, disk_info::Partition, SeekFrom}, 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; 353 354 let fat_type: FATType = self.bpb.fat_type; 355 // 获取FAT表的起始扇区（相对分区起始扇区的偏移量） 356 let fat_start_sector = self.fat_start_sector(); 357 let bytes_per_sec = self.bpb.bytes_per_sector as u64; 358 359 // cluster对应的FAT表项在分区内的字节偏移量 360 let fat_bytes_offset = 361 fat_type.get_fat_bytes_offset(cluster, fat_start_sector, bytes_per_sec); 362 363 // FAT表项所在的LBA地址 364 // let fat_ent_lba = self.get_lba_from_offset(self.bytes_to_sector(fat_bytes_offset)); 365 let fat_ent_lba = self.partition.lba_start + fat_bytes_offset / LBA_SIZE as u64; 366 367 // FAT表项在逻辑块内的字节偏移量 368 let blk_offset = self.get_in_block_offset(fat_bytes_offset); 369 370 let mut v = Vec::<u8>::new(); 371 v.resize(self.bpb.bytes_per_sector as usize, 0); 372 self.partition 373 .disk() 374 .read_at(fat_ent_lba as usize, 1 * self.lba_per_sector(), &mut v)?; 375 376 let mut cursor = VecCursor::new(v); 377 cursor.seek(SeekFrom::SeekSet(blk_offset as i64))?; 378 379 let res: FATEntry = match self.bpb.fat_type { 380 FATType::FAT12(_) => { 381 let mut entry = cursor.read_u16()?; 382 // 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。 383 if (current_cluster & 1) > 0 { 384 entry >>= 4; 385 } else { 386 entry &= 0x0fff; 387 } 388 389 if entry == 0 { 390 FATEntry::Unused 391 } else if entry == 0x0ff7 { 392 FATEntry::Bad 393 } else if entry >= 0x0ff8 { 394 FATEntry::EndOfChain 395 } else { 396 FATEntry::Next(Cluster { 397 cluster_num: entry as u64, 398 parent_cluster: current_cluster, 399 }) 400 } 401 } 402 FATType::FAT16(_) => { 403 let entry = cursor.read_u16()?; 404 405 if entry == 0 { 406 FATEntry::Unused 407 } else if entry == 0xfff7 { 408 FATEntry::Bad 409 } else if entry >= 0xfff8 { 410 FATEntry::EndOfChain 411 } else { 412 FATEntry::Next(Cluster { 413 cluster_num: entry as u64, 414 parent_cluster: current_cluster, 415 }) 416 } 417 } 418 FATType::FAT32(_) => { 419 let entry = cursor.read_u32()? & 0x0fffffff; 420 421 match entry { 422 _n if (current_cluster >= 0x0ffffff7 && current_cluster <= 0x0fffffff) => { 423 // 当前簇号不是一个能被获得的簇（可能是文件系统出错了） 424 kerror!("FAT32 get fat entry: current cluster number [{}] is not an allocatable cluster number.", current_cluster); 425 FATEntry::Bad 426 } 427 0 => FATEntry::Unused, 428 0x0ffffff7 => FATEntry::Bad, 429 0x0ffffff8..=0x0fffffff => FATEntry::EndOfChain, 430 _n => FATEntry::Next(Cluster { 431 cluster_num: entry as u64, 432 parent_cluster: current_cluster, 433 }), 434 } 435 } 436 }; 437 return Ok(res); 438 } 439 440 /// @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） 441 /// 442 /// @param cluster 当前簇 443 /// 444 /// @return Ok(u64) 当前簇在FAT表中，存储的信息。 445 /// @return Err(SystemError) 错误码 446 pub fn get_fat_entry_raw(&self, cluster: Cluster) -> Result<u64, SystemError> { 447 let current_cluster = cluster.cluster_num; 448 449 let fat_type: FATType = self.bpb.fat_type; 450 // 获取FAT表的起始扇区（相对分区起始扇区的偏移量） 451 let fat_start_sector = self.fat_start_sector(); 452 let bytes_per_sec = self.bpb.bytes_per_sector as u64; 453 454 // cluster对应的FAT表项在分区内的字节偏移量 455 let fat_bytes_offset = 456 fat_type.get_fat_bytes_offset(cluster, fat_start_sector, bytes_per_sec); 457 458 // FAT表项所在的LBA地址 459 let fat_ent_lba = self.get_lba_from_offset(self.bytes_to_sector(fat_bytes_offset)); 460 461 // FAT表项在逻辑块内的字节偏移量 462 let blk_offset = self.get_in_block_offset(fat_bytes_offset); 463 464 let mut v = Vec::<u8>::new(); 465 v.resize(self.bpb.bytes_per_sector as usize, 0); 466 self.partition 467 .disk() 468 .read_at(fat_ent_lba, 1 * self.lba_per_sector(), &mut v)?; 469 470 let mut cursor = VecCursor::new(v); 471 cursor.seek(SeekFrom::SeekSet(blk_offset as i64))?; 472 473 let res = match self.bpb.fat_type { 474 FATType::FAT12(_) => { 475 let mut entry = cursor.read_u16()?; 476 entry = if (current_cluster & 0x0001) > 0 { 477 entry >> 4 478 } else { 479 entry & 0x0fff 480 }; 481 entry as u64 482 } 483 FATType::FAT16(_) => { 484 let entry = (cursor.read_u16()?) as u64; 485 entry 486 } 487 FATType::FAT32(_) => { 488 let entry = cursor.read_u32()? & 0x0fff_ffff; 489 entry as u64 490 } 491 }; 492 493 return Ok(res); 494 } 495 496 /// @brief 获取当前文件系统的root inode，在磁盘上的字节偏移量 497 pub fn root_dir_bytes_offset(&self) -> u64 { 498 match self.bpb.fat_type { 499 FATType::FAT32(s) => { 500 let first_sec_cluster: u64 = (s.root_cluster as u64 - 2) 501 * (self.bpb.sector_per_cluster as u64) 502 + self.first_data_sector; 503 return (self.get_lba_from_offset(first_sec_cluster) * LBA_SIZE) as u64; 504 } 505 _ => { 506 let root_sec = (self.bpb.rsvd_sec_cnt as u64) 507 + (self.bpb.num_fats as u64) * (self.bpb.fat_size_16 as u64); 508 return (self.get_lba_from_offset(root_sec) * LBA_SIZE) as u64; 509 } 510 } 511 } 512 513 /// @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。 514 /// 请注意，当前函数只对FAT12/FAT16生效。对于FAT32,返回None 515 pub fn root_dir_end_bytes_offset(&self) -> Option<u64> { 516 match self.bpb.fat_type { 517 FATType::FAT12(_) | FATType::FAT16(_) => { 518 return Some( 519 self.root_dir_bytes_offset() + (self.bpb.root_entries_cnt as u64) * 32, 520 ); 521 } 522 _ => { 523 return None; 524 } 525 } 526 } 527 528 /// @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) 529 pub fn cluster_bytes_offset(&self, cluster: Cluster) -> u64 { 530 if cluster.cluster_num >= 2 { 531 // 指定簇的第一个扇区号 532 let first_sec_of_cluster = (cluster.cluster_num - 2) 533 * (self.bpb.sector_per_cluster as u64) 534 + self.first_data_sector; 535 return (self.get_lba_from_offset(first_sec_of_cluster) * LBA_SIZE) as u64; 536 } else { 537 return 0; 538 } 539 } 540 541 /// @brief 获取一个空闲簇 542 /// 543 /// @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。 544 /// 545 /// @return Ok(Cluster) 新获取的空闲簇 546 /// @return Err(SystemError) 错误码 547 pub fn allocate_cluster(&self, prev_cluster: Option<Cluster>) -> Result<Cluster, SystemError> { 548 let end_cluster: Cluster = self.max_cluster_number(); 549 let start_cluster: Cluster = match self.bpb.fat_type { 550 FATType::FAT32(_) => { 551 let next_free: u64 = match self.fs_info.0.lock().next_free() { 552 Some(x) => x, 553 None => 0xffffffff, 554 }; 555 if next_free < end_cluster.cluster_num { 556 Cluster::new(next_free) 557 } else { 558 Cluster::new(RESERVED_CLUSTERS as u64) 559 } 560 } 561 _ => Cluster::new(RESERVED_CLUSTERS as u64), 562 }; 563 564 // 寻找一个空的簇 565 let free_cluster: Cluster = match self.get_free_cluster(start_cluster, end_cluster) { 566 Ok(c) => c, 567 Err(_) if start_cluster.cluster_num > RESERVED_CLUSTERS as u64 => { 568 self.get_free_cluster(Cluster::new(RESERVED_CLUSTERS as u64), end_cluster)? 569 } 570 Err(e) => return Err(e), 571 }; 572 573 self.set_entry(free_cluster, FATEntry::EndOfChain)?; 574 // 减少空闲簇计数 575 self.fs_info.0.lock().update_free_count_delta(-1); 576 // 更新搜索空闲簇的参考量 577 self.fs_info 578 .0 579 .lock() 580 .update_next_free((free_cluster.cluster_num + 1) as u32); 581 582 // 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。 583 if let Some(prev_cluster) = prev_cluster { 584 // kdebug!("set entry, prev ={prev_cluster:?}, next = {free_cluster:?}"); 585 self.set_entry(prev_cluster, FATEntry::Next(free_cluster))?; 586 } 587 // 清空新获取的这个簇 588 self.zero_cluster(free_cluster)?; 589 return Ok(free_cluster); 590 } 591 592 /// @brief 释放簇链上的所有簇 593 /// 594 /// @param start_cluster 簇链的第一个簇 595 pub fn deallocate_cluster_chain(&self, start_cluster: Cluster) -> Result<(), SystemError> { 596 let clusters: Vec<Cluster> = self.clusters(start_cluster); 597 for c in clusters { 598 self.deallocate_cluster(c)?; 599 } 600 return Ok(()); 601 } 602 603 /// @brief 释放簇 604 /// 605 /// @param 要释放的簇 606 pub fn deallocate_cluster(&self, cluster: Cluster) -> Result<(), SystemError> { 607 let entry: FATEntry = self.get_fat_entry(cluster)?; 608 // 如果不是坏簇 609 if entry != FATEntry::Bad { 610 self.set_entry(cluster, FATEntry::Unused)?; 611 self.fs_info.0.lock().update_free_count_delta(1); 612 // 安全选项：清空被释放的簇 613 #[cfg(feature = "secure")] 614 self.zero_cluster(cluster)?; 615 return Ok(()); 616 } else { 617 // 不能释放坏簇 618 kerror!("Bad clusters cannot be freed."); 619 return Err(SystemError::EFAULT); 620 } 621 } 622 623 /// @brief 获取文件系统的根目录项 624 pub fn root_dir(&self) -> FATDir { 625 match self.bpb.fat_type { 626 FATType::FAT32(s) => { 627 return FATDir { 628 first_cluster: Cluster::new(s.root_cluster as u64), 629 dir_name: String::from("/"), 630 root_offset: None, 631 short_dir_entry: None, 632 loc: None, 633 }; 634 } 635 _ => FATDir { 636 first_cluster: Cluster::new(0), 637 dir_name: String::from("/"), 638 root_offset: Some(self.root_dir_bytes_offset()), 639 short_dir_entry: None, 640 loc: None, 641 }, 642 } 643 } 644 645 /// @brief 获取FAT表的起始扇区（相对分区起始扇区的偏移量） 646 pub fn fat_start_sector(&self) -> u64 { 647 let active_fat = self.active_fat(); 648 let fat_size = self.fat_size(); 649 return self.bpb.rsvd_sec_cnt as u64 + active_fat * fat_size; 650 } 651 652 /// @brief 获取当前活动的FAT表 653 pub fn active_fat(&self) -> u64 { 654 if self.mirroring_enabled() { 655 return 0; 656 } else { 657 match self.bpb.fat_type { 658 FATType::FAT32(bpb32) => { 659 return (bpb32.ext_flags & 0x0f) as u64; 660 } 661 _ => { 662 return 0; 663 } 664 } 665 } 666 } 667 668 /// @brief 获取当前文件系统的每个FAT表的大小 669 pub fn fat_size(&self) -> u64 { 670 if self.bpb.fat_size_16 != 0 { 671 return self.bpb.fat_size_16 as u64; 672 } else { 673 match self.bpb.fat_type { 674 FATType::FAT32(bpb32) => { 675 return bpb32.fat_size_32 as u64; 676 } 677 678 _ => { 679 panic!("FAT12 and FAT16 volumes should have non-zero BPB_FATSz16"); 680 } 681 } 682 } 683 } 684 685 /// @brief 判断当前文件系统是否启用了FAT表镜像 686 pub fn mirroring_enabled(&self) -> bool { 687 match self.bpb.fat_type { 688 FATType::FAT32(bpb32) => { 689 return (bpb32.ext_flags & 0x80) == 0; 690 } 691 _ => { 692 return false; 693 } 694 } 695 } 696 697 /// @brief 根据分区内的扇区偏移量，获得在磁盘上的LBA地址 698 #[inline] 699 pub fn get_lba_from_offset(&self, in_partition_sec_offset: u64) -> usize { 700 return (self.partition.lba_start 701 + in_partition_sec_offset * (self.bpb.bytes_per_sector as u64 / LBA_SIZE as u64)) 702 as usize; 703 } 704 705 /// @brief 获取每个扇区占用多少个LBA 706 #[inline] 707 pub fn lba_per_sector(&self) -> usize { 708 return self.bpb.bytes_per_sector as usize / LBA_SIZE; 709 } 710 711 /// @brief 将分区内字节偏移量转换为扇区偏移量 712 #[inline] 713 pub fn bytes_to_sector(&self, in_partition_bytes_offset: u64) -> u64 { 714 return in_partition_bytes_offset / (self.bpb.bytes_per_sector as u64); 715 } 716 717 /// @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 718 #[inline] 719 pub fn get_in_partition_bytes_offset(&self, disk_bytes_offset: u64) -> u64 { 720 return disk_bytes_offset - (self.partition.lba_start * LBA_SIZE as u64); 721 } 722 723 /// @brief 根据字节偏移量计算在逻辑块内的字节偏移量 724 #[inline] 725 pub fn get_in_block_offset(&self, bytes_offset: u64) -> u64 { 726 return bytes_offset % LBA_SIZE as u64; 727 } 728 729 /// @brief 获取在FAT表中，以start_cluster开头的FAT链的所有簇的信息 730 /// 731 /// @param start_cluster 整个FAT链的起始簇号 732 pub fn clusters(&self, start_cluster: Cluster) -> Vec<Cluster> { 733 return self.cluster_iter(start_cluster).collect(); 734 } 735 736 /// @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） 737 /// 738 /// @param start_cluster 整个FAT链的起始簇号 739 pub fn num_clusters_chain(&self, start_cluster: Cluster) -> u64 { 740 return self 741 .cluster_iter(start_cluster) 742 .fold(0, |size, _cluster| size + 1); 743 } 744 /// @brief 获取一个簇迭代器对象 745 /// 746 /// @param start_cluster 整个FAT链的起始簇号 747 fn cluster_iter(&self, start_cluster: Cluster) -> ClusterIter { 748 return ClusterIter { 749 current_cluster: Some(start_cluster), 750 fs: self, 751 }; 752 } 753 754 /// @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） 755 #[inline] 756 pub fn get_cluster_by_relative(&self, start_cluster: Cluster, n: usize) -> Option<Cluster> { 757 return self.cluster_iter(start_cluster).skip(n).next(); 758 } 759 760 /// @brief 获取整个簇链的最后一个簇 761 #[inline] 762 pub fn get_last_cluster(&self, start_cluster: Cluster) -> Option<Cluster> { 763 return self.cluster_iter(start_cluster).last(); 764 } 765 766 /// @brief 判断FAT文件系统的shut bit是否正常。 767 /// 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” 768 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 769 /// 770 /// @return Ok(true) 正常 771 /// @return Ok(false) 不正常 772 /// @return Err(SystemError) 在判断时发生错误 773 pub fn is_shut_bit_ok(&mut self) -> Result<bool, SystemError> { 774 match self.bpb.fat_type { 775 FATType::FAT32(_) => { 776 // 对于FAT32, error bit位于第一个扇区的第8字节。 777 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0800_0000; 778 return Ok(bit > 0); 779 } 780 FATType::FAT16(_) => { 781 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x8000; 782 return Ok(bit > 0); 783 } 784 _ => return Ok(true), 785 } 786 } 787 788 /// @brief 判断FAT文件系统的hard error bit是否正常。 789 /// 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 790 /// 卷上的某些扇区可能已损坏。 791 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 792 /// 793 /// @return Ok(true) 正常 794 /// @return Ok(false) 不正常 795 /// @return Err(SystemError) 在判断时发生错误 796 pub fn is_hard_error_bit_ok(&mut self) -> Result<bool, SystemError> { 797 match self.bpb.fat_type { 798 FATType::FAT32(_) => { 799 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x0400_0000; 800 return Ok(bit > 0); 801 } 802 FATType::FAT16(_) => { 803 let bit = self.get_fat_entry_raw(Cluster::new(1))? & 0x4000; 804 return Ok(bit > 0); 805 } 806 _ => return Ok(true), 807 } 808 } 809 810 /// @brief 设置文件系统的shut bit为正常状态 811 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 812 /// 813 /// @return Ok(()) 设置成功 814 /// @return Err(SystemError) 在设置过程中，出现错误 815 pub fn set_shut_bit_ok(&mut self) -> Result<(), SystemError> { 816 match self.bpb.fat_type { 817 FATType::FAT32(_) => { 818 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0800_0000; 819 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 820 821 return Ok(()); 822 } 823 824 FATType::FAT16(_) => { 825 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x8000; 826 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 827 return Ok(()); 828 } 829 _ => return Ok(()), 830 } 831 } 832 833 /// @brief 设置文件系统的hard error bit为正常状态 834 /// 参考资料：https://thestarman.pcministry.com/DOS/DirtyShutdownFlag.html 835 /// 836 /// @return Ok(()) 设置成功 837 /// @return Err(SystemError) 在设置过程中，出现错误 838 pub fn set_hard_error_bit_ok(&mut self) -> Result<(), SystemError> { 839 match self.bpb.fat_type { 840 FATType::FAT32(_) => { 841 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x0400_0000; 842 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 843 return Ok(()); 844 } 845 846 FATType::FAT16(_) => { 847 let raw_entry = self.get_fat_entry_raw(Cluster::new(1))? | 0x4000; 848 self.set_entry(Cluster::new(1), FATEntry::Next(Cluster::new(raw_entry)))?; 849 return Ok(()); 850 } 851 _ => return Ok(()), 852 } 853 } 854 855 /// @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 856 pub fn umount(&mut self) -> Result<(), SystemError> { 857 self.fs_info.0.lock().flush(&self.partition)?; 858 859 self.set_shut_bit_ok()?; 860 861 self.set_hard_error_bit_ok()?; 862 863 self.partition.disk().sync()?; 864 865 return Ok(()); 866 } 867 868 /// @brief 获取文件系统的最大簇号 869 pub fn max_cluster_number(&self) -> Cluster { 870 match self.bpb.fat_type { 871 FATType::FAT32(s) => { 872 // FAT32 873 874 // 数据扇区数量（总扇区数-保留扇区-FAT占用的扇区） 875 let data_sec: u64 = self.bpb.total_sectors_32 as u64 876 - (self.bpb.rsvd_sec_cnt as u64 877 + self.bpb.num_fats as u64 * s.fat_size_32 as u64); 878 879 // 数据区的簇数量 880 let total_clusters: u64 = data_sec / self.bpb.sector_per_cluster as u64; 881 882 // 返回最大的簇号 883 return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); 884 } 885 886 _ => { 887 // FAT12 / FAT16 888 let root_dir_sectors: u64 = (((self.bpb.root_entries_cnt as u64) * 32) 889 + self.bpb.bytes_per_sector as u64 890 - 1) 891 / self.bpb.bytes_per_sector as u64; 892 // 数据区扇区数 893 let data_sec: u64 = self.bpb.total_sectors_16 as u64 894 - (self.bpb.rsvd_sec_cnt as u64 895 + (self.bpb.num_fats as u64 * self.bpb.fat_size_16 as u64) 896 + root_dir_sectors); 897 let total_clusters = data_sec / self.bpb.sector_per_cluster as u64; 898 return Cluster::new(total_clusters + RESERVED_CLUSTERS as u64 - 1); 899 } 900 } 901 } 902 903 /// @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 904 /// 905 /// @param start_cluster 起始簇号 906 /// @param end_cluster 终止簇号（不包含） 907 /// 908 /// @return Ok(Cluster) 寻找到的空闲簇 909 /// @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. 910 pub fn get_free_cluster( 911 &self, 912 start_cluster: Cluster, 913 end_cluster: Cluster, 914 ) -> Result<Cluster, SystemError> { 915 let max_cluster: Cluster = self.max_cluster_number(); 916 let mut cluster: u64 = start_cluster.cluster_num; 917 918 let fat_type: FATType = self.bpb.fat_type; 919 let fat_start_sector: u64 = self.fat_start_sector(); 920 let bytes_per_sec: u64 = self.bpb.bytes_per_sector as u64; 921 922 match fat_type { 923 FATType::FAT12(_) => { 924 let part_bytes_offset: u64 = 925 fat_type.get_fat_bytes_offset(start_cluster, fat_start_sector, bytes_per_sec); 926 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 927 928 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 929 930 // 由于FAT12的FAT表不大于6K，因此直接读取6K 931 let num_lba = (6 * 1024) / LBA_SIZE; 932 let mut v: Vec<u8> = Vec::new(); 933 v.resize(num_lba * LBA_SIZE, 0); 934 self.partition.disk().read_at(lba, num_lba, &mut v)?; 935 936 let mut cursor: VecCursor = VecCursor::new(v); 937 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 938 939 let mut packed_val: u16 = cursor.read_u16()?; 940 loop { 941 let val = if (cluster & 0x1) > 0 { 942 packed_val >> 4 943 } else { 944 packed_val & 0x0fff 945 }; 946 if val == 0 { 947 return Ok(Cluster::new(cluster as u64)); 948 } 949 950 cluster += 1; 951 952 // 磁盘无剩余空间，或者簇号达到给定的最大值 953 if cluster == end_cluster.cluster_num || cluster == max_cluster.cluster_num { 954 return Err(SystemError::ENOSPC); 955 } 956 957 packed_val = match cluster & 1 { 958 0 => cursor.read_u16()?, 959 _ => { 960 let next_byte = cursor.read_u8()? as u16; 961 (packed_val >> 8) | (next_byte << 8) 962 } 963 }; 964 } 965 } 966 FATType::FAT16(_) => { 967 // todo: 优化这里，减少读取磁盘的次数。 968 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { 969 let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( 970 Cluster::new(cluster), 971 fat_start_sector, 972 bytes_per_sec, 973 ); 974 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 975 976 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 977 978 let mut v: Vec<u8> = Vec::new(); 979 v.resize(self.lba_per_sector() * LBA_SIZE, 0); 980 self.partition 981 .disk() 982 .read_at(lba, self.lba_per_sector(), &mut v)?; 983 984 let mut cursor: VecCursor = VecCursor::new(v); 985 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 986 987 let val = cursor.read_u16()?; 988 // 找到空闲簇 989 if val == 0 { 990 return Ok(Cluster::new(val as u64)); 991 } 992 cluster += 1; 993 } 994 995 // 磁盘无剩余空间，或者簇号达到给定的最大值 996 return Err(SystemError::ENOSPC); 997 } 998 FATType::FAT32(_) => { 999 // todo: 优化这里，减少读取磁盘的次数。 1000 while cluster < end_cluster.cluster_num && cluster < max_cluster.cluster_num { 1001 let part_bytes_offset: u64 = fat_type.get_fat_bytes_offset( 1002 Cluster::new(cluster), 1003 fat_start_sector, 1004 bytes_per_sec, 1005 ); 1006 let in_block_offset = self.get_in_block_offset(part_bytes_offset); 1007 1008 let lba = self.get_lba_from_offset(self.bytes_to_sector(part_bytes_offset)); 1009 1010 let mut v: Vec<u8> = Vec::new(); 1011 v.resize(self.lba_per_sector() * LBA_SIZE, 0); 1012 self.partition 1013 .disk() 1014 .read_at(lba, self.lba_per_sector(), &mut v)?; 1015 1016 let mut cursor: VecCursor = VecCursor::new(v); 1017 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1018 1019 let val = cursor.read_u32()? & 0x0fffffff; 1020 1021 if val == 0 { 1022 return Ok(Cluster::new(cluster)); 1023 } 1024 cluster += 1; 1025 } 1026 1027 // 磁盘无剩余空间，或者簇号达到给定的最大值 1028 return Err(SystemError::ENOSPC); 1029 } 1030 } 1031 } 1032 1033 /// @brief 在FAT表中，设置指定的簇的信息。 1034 /// 1035 /// @param cluster 目标簇 1036 /// @param fat_entry 这个簇在FAT表中，存储的信息（下一个簇的簇号） 1037 pub fn set_entry(&self, cluster: Cluster, fat_entry: FATEntry) -> Result<(), SystemError> { 1038 // fat表项在分区上的字节偏移量 1039 let fat_part_bytes_offset: u64 = self.bpb.fat_type.get_fat_bytes_offset( 1040 cluster, 1041 self.fat_start_sector(), 1042 self.bpb.bytes_per_sector as u64, 1043 ); 1044 1045 match self.bpb.fat_type { 1046 FATType::FAT12(_) => { 1047 // 计算要写入的值 1048 let raw_val: u16 = match fat_entry { 1049 FATEntry::Unused => 0, 1050 FATEntry::Bad => 0xff7, 1051 FATEntry::EndOfChain => 0xfff, 1052 FATEntry::Next(c) => c.cluster_num as u16, 1053 }; 1054 1055 let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); 1056 1057 let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); 1058 1059 let mut v: Vec<u8> = Vec::new(); 1060 v.resize(LBA_SIZE, 0); 1061 self.partition.disk().read_at(lba, 1, &mut v)?; 1062 1063 let mut cursor: VecCursor = VecCursor::new(v); 1064 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1065 1066 let old_val: u16 = cursor.read_u16()?; 1067 let new_val: u16 = if (cluster.cluster_num & 0x1) > 0 { 1068 (old_val & 0x000f) | (raw_val << 4) 1069 } else { 1070 (old_val & 0xf000) | raw_val 1071 }; 1072 1073 // 写回数据到磁盘上 1074 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1075 cursor.write_u16(new_val)?; 1076 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1077 return Ok(()); 1078 } 1079 FATType::FAT16(_) => { 1080 // 计算要写入的值 1081 let raw_val: u16 = match fat_entry { 1082 FATEntry::Unused => 0, 1083 FATEntry::Bad => 0xfff7, 1084 FATEntry::EndOfChain => 0xfdff, 1085 FATEntry::Next(c) => c.cluster_num as u16, 1086 }; 1087 1088 let in_block_offset = self.get_in_block_offset(fat_part_bytes_offset); 1089 1090 let lba = self.get_lba_from_offset(self.bytes_to_sector(fat_part_bytes_offset)); 1091 1092 let mut v: Vec<u8> = Vec::new(); 1093 v.resize(LBA_SIZE, 0); 1094 self.partition.disk().read_at(lba, 1, &mut v)?; 1095 1096 let mut cursor: VecCursor = VecCursor::new(v); 1097 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1098 1099 cursor.write_u16(raw_val)?; 1100 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1101 1102 return Ok(()); 1103 } 1104 FATType::FAT32(_) => { 1105 let fat_size: u64 = self.fat_size(); 1106 let bound: u64 = if self.mirroring_enabled() { 1107 1 1108 } else { 1109 self.bpb.num_fats as u64 1110 }; 1111 // kdebug!("set entry, bound={bound}, fat_size={fat_size}"); 1112 for i in 0..bound { 1113 // 当前操作的FAT表在磁盘上的字节偏移量 1114 let f_offset: u64 = fat_part_bytes_offset + i * fat_size; 1115 let in_block_offset: u64 = self.get_in_block_offset(f_offset); 1116 let lba = self.get_lba_from_offset(self.bytes_to_sector(f_offset)); 1117 1118 // kdebug!("set entry, lba={lba}, in_block_offset={in_block_offset}"); 1119 let mut v: Vec<u8> = Vec::new(); 1120 v.resize(LBA_SIZE, 0); 1121 self.partition.disk().read_at(lba, 1, &mut v)?; 1122 1123 let mut cursor: VecCursor = VecCursor::new(v); 1124 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1125 1126 // FAT32的高4位保留 1127 let old_bits = cursor.read_u32()? & 0xf0000000; 1128 1129 if fat_entry == FATEntry::Unused 1130 && cluster.cluster_num >= 0x0ffffff7 1131 && cluster.cluster_num <= 0x0fffffff 1132 { 1133 kerror!( 1134 "FAT32: Reserved Cluster {:?} cannot be marked as free", 1135 cluster 1136 ); 1137 return Err(SystemError::EPERM); 1138 } 1139 1140 // 计算要写入的值 1141 let mut raw_val: u32 = match fat_entry { 1142 FATEntry::Unused => 0, 1143 FATEntry::Bad => 0x0FFFFFF7, 1144 FATEntry::EndOfChain => 0x0FFFFFFF, 1145 FATEntry::Next(c) => c.cluster_num as u32, 1146 }; 1147 1148 // 恢复保留位 1149 raw_val |= old_bits; 1150 1151 // kdebug!("sent entry, raw_val={raw_val}"); 1152 1153 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1154 cursor.write_u32(raw_val)?; 1155 1156 self.partition.disk().write_at(lba, 1, cursor.as_slice())?; 1157 } 1158 1159 return Ok(()); 1160 } 1161 } 1162 } 1163 1164 /// @brief 清空指定的簇 1165 /// 1166 /// @param cluster 要被清空的簇 1167 pub fn zero_cluster(&self, cluster: Cluster) -> Result<(), SystemError> { 1168 // 准备数据，用于写入 1169 let zeros: Vec<u8> = vec![0u8; self.bytes_per_cluster() as usize]; 1170 let offset: usize = self.cluster_bytes_offset(cluster) as usize; 1171 self.partition 1172 .disk() 1173 .device() 1174 .write_at(offset, zeros.len(), zeros.as_slice())?; 1175 return Ok(()); 1176 } 1177 } 1178 1179 impl Drop for FATFileSystem { 1180 fn drop(&mut self) { 1181 let r = self.umount(); 1182 if r.is_err() { 1183 kerror!( 1184 "Umount FAT filesystem failed: errno={:?}, FS detail:{self:?}", 1185 r.unwrap_err() 1186 ); 1187 } 1188 } 1189 } 1190 1191 impl FATFsInfo { 1192 const LEAD_SIG: u32 = 0x41615252; 1193 const STRUC_SIG: u32 = 0x61417272; 1194 const TRAIL_SIG: u32 = 0xAA550000; 1195 const FS_INFO_SIZE: u64 = 512; 1196 1197 /// @brief 从磁盘上读取FAT文件系统的FSInfo结构体 1198 /// 1199 /// @param partition 磁盘分区 1200 /// @param in_disk_fs_info_offset FSInfo扇区在磁盘内的字节偏移量（单位：字节） 1201 /// @param bytes_per_sec 每扇区字节数 1202 pub fn new( 1203 partition: Arc<Partition>, 1204 in_disk_fs_info_offset: u64, 1205 bytes_per_sec: usize, 1206 ) -> Result<Self, SystemError> { 1207 let mut v = Vec::<u8>::new(); 1208 v.resize(bytes_per_sec, 0); 1209 1210 // 计算fs_info扇区在磁盘上的字节偏移量，从磁盘读取数据 1211 partition 1212 .disk() 1213 .read_at(in_disk_fs_info_offset as usize / LBA_SIZE, 1, &mut v)?; 1214 let mut cursor = VecCursor::new(v); 1215 1216 let mut fsinfo = FATFsInfo::default(); 1217 1218 fsinfo.lead_sig = cursor.read_u32()?; 1219 cursor.seek(SeekFrom::SeekCurrent(480))?; 1220 fsinfo.struc_sig = cursor.read_u32()?; 1221 fsinfo.free_count = cursor.read_u32()?; 1222 fsinfo.next_free = cursor.read_u32()?; 1223 1224 cursor.seek(SeekFrom::SeekCurrent(12))?; 1225 1226 fsinfo.trail_sig = cursor.read_u32()?; 1227 fsinfo.dirty = false; 1228 fsinfo.offset = Some(in_disk_fs_info_offset); 1229 1230 if fsinfo.is_valid() { 1231 return Ok(fsinfo); 1232 } else { 1233 kerror!("Error occurred while parsing FATFsInfo."); 1234 return Err(SystemError::EINVAL); 1235 } 1236 } 1237 1238 /// @brief 判断是否为正确的FsInfo结构体 1239 fn is_valid(&self) -> bool { 1240 self.lead_sig == Self::LEAD_SIG 1241 && self.struc_sig == Self::STRUC_SIG 1242 && self.trail_sig == Self::TRAIL_SIG 1243 } 1244 1245 /// @brief 根据fsinfo的信息，计算当前总的空闲簇数量 1246 /// 1247 /// @param 当前文件系统的最大簇号 1248 pub fn count_free_cluster(&self, max_cluster: Cluster) -> Option<u64> { 1249 let count_clusters = max_cluster.cluster_num - RESERVED_CLUSTERS as u64 + 1; 1250 // 信息不合理，当前的FsInfo中存储的free count大于计算出来的值 1251 if self.free_count as u64 > count_clusters { 1252 return None; 1253 } else { 1254 match self.free_count { 1255 // free count字段不可用 1256 0xffffffff => return None, 1257 // 返回FsInfo中存储的数据 1258 n => return Some(n as u64), 1259 } 1260 } 1261 } 1262 1263 /// @brief 更新FsInfo中的“空闲簇统计信息“为new_count 1264 /// 1265 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 1266 pub fn update_free_count_abs(&mut self, new_count: u32) { 1267 self.free_count = new_count; 1268 } 1269 1270 /// @brief 更新FsInfo中的“空闲簇统计信息“，把它加上delta. 1271 /// 1272 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 1273 pub fn update_free_count_delta(&mut self, delta: i32) { 1274 self.free_count = (self.free_count as i32 + delta) as u32; 1275 } 1276 1277 /// @brief 更新FsInfo中的“第一个空闲簇统计信息“为next_free. 1278 /// 1279 /// 请注意，除非手动调用`flush()`，否则本函数不会将数据刷入磁盘 1280 pub fn update_next_free(&mut self, next_free: u32) { 1281 // 这个值是参考量，不一定要准确，仅供加速查找 1282 self.next_free = next_free; 1283 } 1284 1285 /// @brief 获取fs info 记载的第一个空闲簇。（不一定准确，仅供参考） 1286 pub fn next_free(&self) -> Option<u64> { 1287 match self.next_free { 1288 0xffffffff => return None, 1289 0 | 1 => return None, 1290 n => return Some(n as u64), 1291 }; 1292 } 1293 1294 /// @brief 把fs info刷入磁盘 1295 /// 1296 /// @param partition fs info所在的分区 1297 pub fn flush(&self, partition: &Arc<Partition>) -> Result<(), SystemError> { 1298 if let Some(off) = self.offset { 1299 let in_block_offset = off % LBA_SIZE as u64; 1300 1301 let lba = off as usize / LBA_SIZE; 1302 1303 let mut v: Vec<u8> = Vec::new(); 1304 v.resize(LBA_SIZE, 0); 1305 partition.disk().read_at(lba, 1, &mut v)?; 1306 1307 let mut cursor: VecCursor = VecCursor::new(v); 1308 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1309 1310 cursor.write_u32(self.lead_sig)?; 1311 cursor.seek(SeekFrom::SeekCurrent(480))?; 1312 cursor.write_u32(self.struc_sig)?; 1313 cursor.write_u32(self.free_count)?; 1314 cursor.write_u32(self.next_free)?; 1315 cursor.seek(SeekFrom::SeekCurrent(12))?; 1316 cursor.write_u32(self.trail_sig)?; 1317 1318 partition.disk().write_at(lba, 1, cursor.as_slice())?; 1319 } 1320 return Ok(()); 1321 } 1322 1323 /// @brief 读取磁盘上的Fs Info扇区，将里面的内容更新到结构体中 1324 /// 1325 /// @param partition fs info所在的分区 1326 pub fn update(&mut self, partition: Arc<Partition>) -> Result<(), SystemError> { 1327 if let Some(off) = self.offset { 1328 let in_block_offset = off % LBA_SIZE as u64; 1329 1330 let lba = off as usize / LBA_SIZE; 1331 1332 let mut v: Vec<u8> = Vec::new(); 1333 v.resize(LBA_SIZE, 0); 1334 partition.disk().read_at(lba, 1, &mut v)?; 1335 let mut cursor: VecCursor = VecCursor::new(v); 1336 cursor.seek(SeekFrom::SeekSet(in_block_offset as i64))?; 1337 self.lead_sig = cursor.read_u32()?; 1338 1339 cursor.seek(SeekFrom::SeekCurrent(480))?; 1340 self.struc_sig = cursor.read_u32()?; 1341 self.free_count = cursor.read_u32()?; 1342 self.next_free = cursor.read_u32()?; 1343 cursor.seek(SeekFrom::SeekCurrent(12))?; 1344 self.trail_sig = cursor.read_u32()?; 1345 } 1346 return Ok(()); 1347 } 1348 } 1349 1350 impl IndexNode for LockedFATInode { 1351 fn read_at( 1352 &self, 1353 offset: usize, 1354 len: usize, 1355 buf: &mut [u8], 1356 _data: &mut FilePrivateData, 1357 ) -> Result<usize, SystemError> { 1358 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1359 match &guard.inode_type { 1360 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 1361 let r = f.read( 1362 &guard.fs.upgrade().unwrap(), 1363 &mut buf[0..len], 1364 offset as u64, 1365 ); 1366 guard.update_metadata(); 1367 return r; 1368 } 1369 FATDirEntry::Dir(_) => { 1370 return Err(SystemError::EISDIR); 1371 } 1372 FATDirEntry::UnInit => { 1373 kerror!("FATFS: param: Inode_type uninitialized."); 1374 return Err(SystemError::EROFS); 1375 } 1376 } 1377 } 1378 1379 fn write_at( 1380 &self, 1381 offset: usize, 1382 len: usize, 1383 buf: &[u8], 1384 _data: &mut FilePrivateData, 1385 ) -> Result<usize, SystemError> { 1386 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1387 let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap(); 1388 1389 match &mut guard.inode_type { 1390 FATDirEntry::File(f) | FATDirEntry::VolId(f) => { 1391 let r = f.write(fs, &buf[0..len], offset as u64); 1392 guard.update_metadata(); 1393 return r; 1394 } 1395 FATDirEntry::Dir(_) => { 1396 return Err(SystemError::EISDIR); 1397 } 1398 FATDirEntry::UnInit => { 1399 kerror!("FATFS: param: Inode_type uninitialized."); 1400 return Err(SystemError::EROFS); 1401 } 1402 } 1403 } 1404 1405 fn poll(&self) -> Result<PollStatus, SystemError> { 1406 // 加锁 1407 let inode: SpinLockGuard<FATInode> = self.0.lock(); 1408 1409 // 检查当前inode是否为一个文件夹，如果是的话，就返回错误 1410 if inode.metadata.file_type == FileType::Dir { 1411 return Err(SystemError::EISDIR); 1412 } 1413 1414 return Ok(PollStatus::READ | PollStatus::WRITE); 1415 } 1416 1417 fn create( 1418 &self, 1419 name: &str, 1420 file_type: FileType, 1421 _mode: u32, 1422 ) -> Result<Arc<dyn IndexNode>, SystemError> { 1423 // 由于FAT32不支持文件权限的功能，因此忽略mode参数 1424 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 1464 fn list(&self) -> Result<Vec<String>, SystemError> { 1465 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1466 let fatent: &FATDirEntry = &guard.inode_type; 1467 match fatent { 1468 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1469 return Err(SystemError::ENOTDIR); 1470 } 1471 FATDirEntry::Dir(dir) => { 1472 // 获取当前目录下的所有目录项 1473 let mut ret: Vec<String> = Vec::new(); 1474 let dir_iter: FATDirIter = dir.to_iter(guard.fs.upgrade().unwrap()); 1475 for ent in dir_iter { 1476 ret.push(ent.name()); 1477 1478 // ====== 生成inode缓存，存入B树 1479 let name: String = ent.name(); 1480 // kdebug!("name={name}"); 1481 1482 if guard.children.contains_key(&name.to_uppercase()) == false 1483 && name != "." 1484 && name != ".." 1485 { 1486 // 创建新的inode 1487 let entry_inode: Arc<LockedFATInode> = LockedFATInode::new( 1488 guard.fs.upgrade().unwrap(), 1489 guard.self_ref.clone(), 1490 ent, 1491 ); 1492 // 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 1493 guard 1494 .children 1495 .insert(name.to_uppercase(), entry_inode.clone()); 1496 } 1497 } 1498 return Ok(ret); 1499 } 1500 FATDirEntry::UnInit => { 1501 kerror!("FATFS: param: Inode_type uninitialized."); 1502 return Err(SystemError::EROFS); 1503 } 1504 } 1505 } 1506 1507 fn find(&self, name: &str) -> Result<Arc<dyn IndexNode>, SystemError> { 1508 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1509 let target = guard.find(name)?; 1510 return Ok(target); 1511 } 1512 1513 fn open(&self, _data: &mut FilePrivateData, _mode: &FileMode) -> Result<(), SystemError> { 1514 return Ok(()); 1515 } 1516 1517 fn close(&self, _data: &mut FilePrivateData) -> Result<(), SystemError> { 1518 return Ok(()); 1519 } 1520 1521 fn unlink(&self, name: &str) -> Result<(), SystemError> { 1522 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1523 let target: Arc<LockedFATInode> = guard.find(name)?; 1524 // 对目标inode上锁，以防更改 1525 let target_guard: SpinLockGuard<FATInode> = target.0.lock(); 1526 // 先从缓存删除 1527 guard.children.remove(&name.to_uppercase()); 1528 1529 let dir = match &guard.inode_type { 1530 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1531 return Err(SystemError::ENOTDIR); 1532 } 1533 FATDirEntry::Dir(d) => d, 1534 FATDirEntry::UnInit => { 1535 kerror!("FATFS: param: Inode_type uninitialized."); 1536 return Err(SystemError::EROFS); 1537 } 1538 }; 1539 // 检查文件是否存在 1540 dir.check_existence(name, Some(false), guard.fs.upgrade().unwrap())?; 1541 1542 // 再从磁盘删除 1543 let r = dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); 1544 drop(target_guard); 1545 return r; 1546 } 1547 1548 fn rmdir(&self, name: &str) -> Result<(), SystemError> { 1549 let mut guard: SpinLockGuard<FATInode> = self.0.lock(); 1550 let target: Arc<LockedFATInode> = guard.find(name)?; 1551 // 对目标inode上锁，以防更改 1552 let target_guard: SpinLockGuard<FATInode> = target.0.lock(); 1553 // 先从缓存删除 1554 guard.children.remove(&name.to_uppercase()); 1555 1556 let dir = match &guard.inode_type { 1557 FATDirEntry::File(_) | FATDirEntry::VolId(_) => { 1558 return Err(SystemError::ENOTDIR); 1559 } 1560 FATDirEntry::Dir(d) => d, 1561 FATDirEntry::UnInit => { 1562 kerror!("FATFS: param: Inode_type uninitialized."); 1563 return Err(SystemError::EROFS); 1564 } 1565 }; 1566 // 检查文件夹是否存在 1567 dir.check_existence(name, Some(true), guard.fs.upgrade().unwrap())?; 1568 1569 // 再从磁盘删除 1570 let r: Result<(), SystemError> = 1571 dir.remove(guard.fs.upgrade().unwrap().clone(), name, true); 1572 if r.is_ok() { 1573 return r; 1574 } else { 1575 let r = r.unwrap_err(); 1576 if r == SystemError::ENOTEMPTY { 1577 // 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 1578 guard.children.insert(name.to_uppercase(), target.clone()); 1579 drop(target_guard); 1580 } 1581 return Err(r); 1582 } 1583 } 1584 1585 fn get_entry_name(&self, ino: InodeId) -> Result<String, SystemError> { 1586 let guard: SpinLockGuard<FATInode> = self.0.lock(); 1587 if guard.metadata.file_type != FileType::Dir { 1588 return Err(SystemError::ENOTDIR); 1589 } 1590 match ino { 1591 0 => { 1592 return Ok(String::from(".")); 1593 } 1594 1 => { 1595 return Ok(String::from("..")); 1596 } 1597 ino => { 1598 // 暴力遍历所有的children，判断inode id是否相同 1599 // TODO: 优化这里，这个地方性能很差！ 1600 let mut key: Vec<String> = guard 1601 .children 1602 .keys() 1603 .filter(|k| guard.children.get(*k).unwrap().metadata().unwrap().inode_id == ino) 1604 .cloned() 1605 .collect(); 1606 1607 match key.len() { 1608 0=>{return Err(SystemError::ENOENT);} 1609 1=>{return Ok(key.remove(0));} 1610 _ => 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) 1611 } 1612 } 1613 } 1614 } 1615 } 1616 1617 impl Default for FATFsInfo { 1618 fn default() -> Self { 1619 return FATFsInfo { 1620 lead_sig: FATFsInfo::LEAD_SIG, 1621 struc_sig: FATFsInfo::STRUC_SIG, 1622 free_count: 0xFFFFFFFF, 1623 next_free: RESERVED_CLUSTERS, 1624 trail_sig: FATFsInfo::TRAIL_SIG, 1625 dirty: false, 1626 offset: None, 1627 }; 1628 } 1629 } 1630 1631 impl Cluster { 1632 pub fn new(cluster: u64) -> Self { 1633 return Cluster { 1634 cluster_num: cluster, 1635 parent_cluster: 0, 1636 }; 1637 } 1638 } 1639 1640 /// @brief 用于迭代FAT表的内容的簇迭代器对象 1641 #[derive(Debug)] 1642 struct ClusterIter<'a> { 1643 /// 迭代器的next要返回的簇 1644 current_cluster: Option<Cluster>, 1645 /// 属于的文件系统 1646 fs: &'a FATFileSystem, 1647 } 1648 1649 impl<'a> Iterator for ClusterIter<'a> { 1650 type Item = Cluster; 1651 1652 fn next(&mut self) -> Option<Self::Item> { 1653 // 当前要返回的簇 1654 let ret: Option<Cluster> = self.current_cluster; 1655 1656 // 获得下一个要返回簇 1657 let new: Option<Cluster> = match self.current_cluster { 1658 Some(c) => { 1659 let entry: Option<FATEntry> = self.fs.get_fat_entry(c).ok(); 1660 match entry { 1661 Some(FATEntry::Next(c)) => Some(c), 1662 _ => None, 1663 } 1664 } 1665 _ => None, 1666 }; 1667 1668 self.current_cluster = new; 1669 return ret; 1670 } 1671 } 1672