VirtualFileSystem.cpp 18 KB

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  1. #include "VirtualFileSystem.h"
  2. #include "FileDescriptor.h"
  3. #include "FileSystem.h"
  4. #include <AK/FileSystemPath.h>
  5. #include <AK/StringBuilder.h>
  6. #include <AK/kmalloc.h>
  7. #include <AK/kstdio.h>
  8. #include <AK/ktime.h>
  9. #include "CharacterDevice.h"
  10. #include <LibC/errno_numbers.h>
  11. #include <Kernel/Process.h>
  12. //#define VFS_DEBUG
  13. static VFS* s_the;
  14. VFS& VFS::the()
  15. {
  16. ASSERT(s_the);
  17. return *s_the;
  18. }
  19. VFS::VFS()
  20. {
  21. #ifdef VFS_DEBUG
  22. kprintf("VFS: Constructing VFS\n");
  23. #endif
  24. s_the = this;
  25. }
  26. VFS::~VFS()
  27. {
  28. }
  29. InodeIdentifier VFS::root_inode_id() const
  30. {
  31. ASSERT(m_root_inode);
  32. return m_root_inode->identifier();
  33. }
  34. bool VFS::mount(RetainPtr<FS>&& file_system, const String& path)
  35. {
  36. ASSERT(file_system);
  37. int error;
  38. auto inode = resolve_path(path, root_inode_id(), error);
  39. if (!inode.is_valid()) {
  40. kprintf("VFS: mount can't resolve mount point '%s'\n", path.characters());
  41. return false;
  42. }
  43. kprintf("VFS: mounting %s{%p} at %s (inode: %u)\n", file_system->class_name(), file_system.ptr(), path.characters(), inode.index());
  44. // FIXME: check that this is not already a mount point
  45. auto mount = make<Mount>(inode, move(file_system));
  46. m_mounts.append(move(mount));
  47. return true;
  48. }
  49. bool VFS::mount_root(RetainPtr<FS>&& file_system)
  50. {
  51. if (m_root_inode) {
  52. kprintf("VFS: mount_root can't mount another root\n");
  53. return false;
  54. }
  55. auto mount = make<Mount>(InodeIdentifier(), move(file_system));
  56. auto root_inode_id = mount->guest().fs()->root_inode();
  57. auto root_inode = mount->guest().fs()->get_inode(root_inode_id);
  58. if (!root_inode->is_directory()) {
  59. kprintf("VFS: root inode (%02u:%08u) for / is not a directory :(\n", root_inode_id.fsid(), root_inode_id.index());
  60. return false;
  61. }
  62. m_root_inode = move(root_inode);
  63. kprintf("VFS: mounted root on %s{%p}\n",
  64. m_root_inode->fs().class_name(),
  65. &m_root_inode->fs());
  66. m_mounts.append(move(mount));
  67. return true;
  68. }
  69. auto VFS::find_mount_for_host(InodeIdentifier inode) -> Mount*
  70. {
  71. for (auto& mount : m_mounts) {
  72. if (mount->host() == inode)
  73. return mount.ptr();
  74. }
  75. return nullptr;
  76. }
  77. auto VFS::find_mount_for_guest(InodeIdentifier inode) -> Mount*
  78. {
  79. for (auto& mount : m_mounts) {
  80. if (mount->guest() == inode)
  81. return mount.ptr();
  82. }
  83. return nullptr;
  84. }
  85. bool VFS::is_vfs_root(InodeIdentifier inode) const
  86. {
  87. return inode == root_inode_id();
  88. }
  89. void VFS::traverse_directory_inode(Inode& dir_inode, Function<bool(const FS::DirectoryEntry&)> callback)
  90. {
  91. dir_inode.traverse_as_directory([&] (const FS::DirectoryEntry& entry) {
  92. InodeIdentifier resolved_inode;
  93. if (auto mount = find_mount_for_host(entry.inode))
  94. resolved_inode = mount->guest();
  95. else
  96. resolved_inode = entry.inode;
  97. if (dir_inode.identifier().is_root_inode() && !is_vfs_root(dir_inode.identifier()) && !strcmp(entry.name, "..")) {
  98. auto mount = find_mount_for_guest(entry.inode);
  99. ASSERT(mount);
  100. resolved_inode = mount->host();
  101. }
  102. callback(FS::DirectoryEntry(entry.name, entry.name_length, resolved_inode, entry.file_type));
  103. return true;
  104. });
  105. }
  106. RetainPtr<FileDescriptor> VFS::open(RetainPtr<Device>&& device, int& error, int options)
  107. {
  108. // FIXME: Respect options.
  109. (void) options;
  110. (void) error;
  111. return FileDescriptor::create(move(device));
  112. }
  113. bool VFS::utime(const String& path, int& error, Inode& base, time_t atime, time_t mtime)
  114. {
  115. auto descriptor = VFS::the().open(move(path), error, 0, 0, base);
  116. if (!descriptor)
  117. return false;
  118. auto& inode = *descriptor->inode();
  119. if (inode.fs().is_readonly()) {
  120. error = -EROFS;
  121. return false;
  122. }
  123. if (inode.metadata().uid != current->euid()) {
  124. error = -EACCES;
  125. return false;
  126. }
  127. error = inode.set_atime(atime);
  128. if (error)
  129. return false;
  130. error = inode.set_mtime(mtime);
  131. if (error)
  132. return false;
  133. return true;
  134. }
  135. bool VFS::stat(const String& path, int& error, int options, Inode& base, struct stat& statbuf)
  136. {
  137. auto inode_id = resolve_path(path, base.identifier(), error, options);
  138. if (!inode_id.is_valid())
  139. return false;
  140. error = FileDescriptor::create(get_inode(inode_id))->fstat(&statbuf);
  141. if (error)
  142. return false;
  143. return true;
  144. }
  145. RetainPtr<FileDescriptor> VFS::open(const String& path, int& error, int options, mode_t mode, Inode& base)
  146. {
  147. auto inode_id = resolve_path(path, base.identifier(), error, options);
  148. auto inode = get_inode(inode_id);
  149. if (options & O_CREAT) {
  150. if (!inode)
  151. return create(path, error, options, mode, base);
  152. else if (options & O_EXCL) {
  153. error = -EEXIST;
  154. return nullptr;
  155. }
  156. }
  157. if (!inode)
  158. return nullptr;
  159. auto metadata = inode->metadata();
  160. // NOTE: Read permission is a bit weird, since O_RDONLY == 0,
  161. // so we check if (NOT write_only OR read_and_write)
  162. if (!(options & O_WRONLY) || (options & O_RDWR)) {
  163. if (!metadata.may_read(*current)) {
  164. error = -EACCES;
  165. return nullptr;
  166. }
  167. }
  168. if ((options & O_WRONLY) || (options & O_RDWR)) {
  169. if (!metadata.may_write(*current)) {
  170. error = -EACCES;
  171. return nullptr;
  172. }
  173. }
  174. if (metadata.is_device()) {
  175. auto it = m_devices.find(encoded_device(metadata.major_device, metadata.minor_device));
  176. if (it == m_devices.end()) {
  177. kprintf("VFS::open: no such device %u,%u\n", metadata.major_device, metadata.minor_device);
  178. return nullptr;
  179. }
  180. auto descriptor = (*it).value->open(error, options);
  181. descriptor->set_original_inode(Badge<VFS>(), move(inode));
  182. return descriptor;
  183. }
  184. return FileDescriptor::create(move(inode));
  185. }
  186. RetainPtr<FileDescriptor> VFS::create(const String& path, int& error, int options, mode_t mode, Inode& base)
  187. {
  188. (void) options;
  189. error = -EWHYTHO;
  190. if (!is_socket(mode) && !is_fifo(mode) && !is_block_device(mode) && !is_character_device(mode)) {
  191. // Turn it into a regular file. (This feels rather hackish.)
  192. mode |= 0100000;
  193. }
  194. RetainPtr<Inode> parent_inode;
  195. auto existing_file = resolve_path_to_inode(path, base, error, &parent_inode);
  196. if (existing_file) {
  197. error = -EEXIST;
  198. return nullptr;
  199. }
  200. if (!parent_inode) {
  201. error = -ENOENT;
  202. return nullptr;
  203. }
  204. if (error != -ENOENT) {
  205. return nullptr;
  206. }
  207. if (!parent_inode->metadata().may_write(*current)) {
  208. error = -EACCES;
  209. return nullptr;
  210. }
  211. FileSystemPath p(path);
  212. dbgprintf("VFS::create_file: '%s' in %u:%u\n", p.basename().characters(), parent_inode->fsid(), parent_inode->index());
  213. auto new_file = parent_inode->fs().create_inode(parent_inode->identifier(), p.basename(), mode, 0, error);
  214. if (!new_file)
  215. return nullptr;
  216. error = 0;
  217. return FileDescriptor::create(move(new_file));
  218. }
  219. bool VFS::mkdir(const String& path, mode_t mode, Inode& base, int& error)
  220. {
  221. error = -EWHYTHO;
  222. RetainPtr<Inode> parent_inode;
  223. auto existing_dir = resolve_path_to_inode(path, base, error, &parent_inode);
  224. if (existing_dir) {
  225. error = -EEXIST;
  226. return false;
  227. }
  228. if (!parent_inode) {
  229. error = -ENOENT;
  230. return false;
  231. }
  232. if (error != -ENOENT) {
  233. return false;
  234. }
  235. if (!parent_inode->metadata().may_write(*current)) {
  236. error = -EACCES;
  237. return false;
  238. }
  239. FileSystemPath p(path);
  240. dbgprintf("VFS::mkdir: '%s' in %u:%u\n", p.basename().characters(), parent_inode->fsid(), parent_inode->index());
  241. auto new_dir = parent_inode->fs().create_directory(parent_inode->identifier(), p.basename(), mode, error);
  242. if (new_dir) {
  243. error = 0;
  244. return true;
  245. }
  246. return false;
  247. }
  248. bool VFS::chmod(const String& path, mode_t mode, Inode& base, int& error)
  249. {
  250. error = -EWHYTHO;
  251. auto inode = resolve_path_to_inode(path, base, error);
  252. if (!inode)
  253. return false;
  254. if (inode->fs().is_readonly()) {
  255. error = -EROFS;
  256. return false;
  257. }
  258. if (current->euid() != inode->metadata().uid) {
  259. error = -EPERM;
  260. return false;
  261. }
  262. // Only change the permission bits.
  263. mode = (inode->mode() & ~04777) | (mode & 04777);
  264. kprintf("VFS::chmod(): %u:%u mode %o\n", inode->fsid(), inode->index(), mode);
  265. if (!inode->chmod(mode, error))
  266. return false;
  267. error = 0;
  268. return true;
  269. }
  270. RetainPtr<Inode> VFS::resolve_path_to_inode(const String& path, Inode& base, int& error, RetainPtr<Inode>* parent_inode)
  271. {
  272. // FIXME: This won't work nicely across mount boundaries.
  273. FileSystemPath p(path);
  274. if (!p.is_valid()) {
  275. error = -EINVAL;
  276. return nullptr;
  277. }
  278. InodeIdentifier parent_id;
  279. auto inode_id = resolve_path(path, base.identifier(), error, 0, &parent_id);
  280. if (parent_inode && parent_id.is_valid())
  281. *parent_inode = get_inode(parent_id);
  282. if (!inode_id.is_valid()) {
  283. error = -ENOENT;
  284. return nullptr;
  285. }
  286. return get_inode(inode_id);
  287. }
  288. bool VFS::link(const String& old_path, const String& new_path, Inode& base, int& error)
  289. {
  290. auto old_inode = resolve_path_to_inode(old_path, base, error);
  291. if (!old_inode)
  292. return false;
  293. RetainPtr<Inode> parent_inode;
  294. auto new_inode = resolve_path_to_inode(new_path, base, error, &parent_inode);
  295. if (new_inode) {
  296. error = -EEXIST;
  297. return false;
  298. }
  299. if (!parent_inode) {
  300. error = -ENOENT;
  301. return false;
  302. }
  303. if (parent_inode->fsid() != old_inode->fsid()) {
  304. error = -EXDEV;
  305. return false;
  306. }
  307. if (parent_inode->fs().is_readonly()) {
  308. error = -EROFS;
  309. return false;
  310. }
  311. if (!parent_inode->add_child(old_inode->identifier(), FileSystemPath(old_path).basename(), 0, error))
  312. return false;
  313. error = 0;
  314. return true;
  315. }
  316. bool VFS::unlink(const String& path, Inode& base, int& error)
  317. {
  318. RetainPtr<Inode> parent_inode;
  319. auto inode = resolve_path_to_inode(path, base, error, &parent_inode);
  320. if (!inode)
  321. return false;
  322. if (inode->is_directory()) {
  323. error = -EISDIR;
  324. return false;
  325. }
  326. if (!parent_inode->metadata().may_write(*current)) {
  327. error = -EACCES;
  328. return false;
  329. }
  330. if (!parent_inode->remove_child(FileSystemPath(path).basename(), error))
  331. return false;
  332. error = 0;
  333. return true;
  334. }
  335. bool VFS::rmdir(const String& path, Inode& base, int& error)
  336. {
  337. error = -EWHYTHO;
  338. RetainPtr<Inode> parent_inode;
  339. auto inode = resolve_path_to_inode(path, base, error, &parent_inode);
  340. if (!inode)
  341. return false;
  342. if (inode->fs().is_readonly()) {
  343. error = -EROFS;
  344. return false;
  345. }
  346. // FIXME: We should return EINVAL if the last component of the path is "."
  347. // FIXME: We should return ENOTEMPTY if the last component of the path is ".."
  348. if (!inode->is_directory()) {
  349. error = -ENOTDIR;
  350. return false;
  351. }
  352. if (!parent_inode->metadata().may_write(*current)) {
  353. error = -EACCES;
  354. return false;
  355. }
  356. if (inode->directory_entry_count() != 2) {
  357. error = -ENOTEMPTY;
  358. return false;
  359. }
  360. dbgprintf("VFS::rmdir: Removing inode %u:%u from parent %u:%u\n", inode->fsid(), inode->index(), parent_inode->fsid(), parent_inode->index());
  361. // To do:
  362. // - Remove '.' in target (--child.link_count)
  363. // - Remove '..' in target (--parent.link_count)
  364. // - Remove target from its parent (--parent.link_count)
  365. if (!inode->remove_child(".", error))
  366. return false;
  367. if (!inode->remove_child("..", error))
  368. return false;
  369. // FIXME: The reverse_lookup here can definitely be avoided.
  370. if (!parent_inode->remove_child(parent_inode->reverse_lookup(inode->identifier()), error))
  371. return false;
  372. error = 0;
  373. return true;
  374. }
  375. InodeIdentifier VFS::resolve_symbolic_link(InodeIdentifier base, Inode& symlink_inode, int& error)
  376. {
  377. auto symlink_contents = symlink_inode.read_entire();
  378. if (!symlink_contents)
  379. return { };
  380. auto linkee = String((const char*)symlink_contents.pointer(), symlink_contents.size());
  381. #ifdef VFS_DEBUG
  382. kprintf("linkee (%s)(%u) from %u:%u\n", linkee.characters(), linkee.length(), base.fsid(), base.index());
  383. #endif
  384. return resolve_path(linkee, base, error);
  385. }
  386. RetainPtr<Inode> VFS::get_inode(InodeIdentifier inode_id)
  387. {
  388. if (!inode_id.is_valid())
  389. return nullptr;
  390. return inode_id.fs()->get_inode(inode_id);
  391. }
  392. String VFS::absolute_path(InodeIdentifier inode_id)
  393. {
  394. auto inode = get_inode(inode_id);
  395. if (!inode)
  396. return { };
  397. return absolute_path(*inode);
  398. }
  399. String VFS::absolute_path(Inode& core_inode)
  400. {
  401. int error;
  402. Vector<InodeIdentifier> lineage;
  403. RetainPtr<Inode> inode = &core_inode;
  404. while (inode->identifier() != root_inode_id()) {
  405. if (auto* mount = find_mount_for_guest(inode->identifier()))
  406. lineage.append(mount->host());
  407. else
  408. lineage.append(inode->identifier());
  409. InodeIdentifier parent_id;
  410. if (inode->is_directory()) {
  411. parent_id = resolve_path("..", inode->identifier(), error);
  412. } else {
  413. parent_id = inode->parent()->identifier();
  414. }
  415. ASSERT(parent_id.is_valid());
  416. inode = get_inode(parent_id);
  417. }
  418. if (lineage.is_empty())
  419. return "/";
  420. lineage.append(root_inode_id());
  421. StringBuilder builder;
  422. for (size_t i = lineage.size() - 1; i >= 1; --i) {
  423. auto& child = lineage[i - 1];
  424. auto parent = lineage[i];
  425. if (auto* mount = find_mount_for_host(parent))
  426. parent = mount->guest();
  427. builder.append('/');
  428. auto parent_inode = get_inode(parent);
  429. builder.append(parent_inode->reverse_lookup(child));
  430. }
  431. return builder.to_string();
  432. }
  433. InodeIdentifier VFS::resolve_path(const String& path, InodeIdentifier base, int& error, int options, InodeIdentifier* parent_id)
  434. {
  435. if (path.is_empty()) {
  436. error = -EINVAL;
  437. return { };
  438. }
  439. auto parts = path.split('/');
  440. InodeIdentifier crumb_id;
  441. if (path[0] == '/')
  442. crumb_id = root_inode_id();
  443. else
  444. crumb_id = base.is_valid() ? base : root_inode_id();
  445. if (parent_id)
  446. *parent_id = crumb_id;
  447. for (unsigned i = 0; i < parts.size(); ++i) {
  448. bool inode_was_root_at_head_of_loop = crumb_id.is_root_inode();
  449. auto& part = parts[i];
  450. if (part.is_empty())
  451. break;
  452. auto crumb_inode = get_inode(crumb_id);
  453. if (!crumb_inode) {
  454. #ifdef VFS_DEBUG
  455. kprintf("invalid metadata\n");
  456. #endif
  457. error = -EIO;
  458. return { };
  459. }
  460. auto metadata = crumb_inode->metadata();
  461. if (!metadata.is_directory()) {
  462. #ifdef VFS_DEBUG
  463. kprintf("parent of <%s> not directory, it's inode %u:%u / %u:%u, mode: %u, size: %u\n", part.characters(), crumb_id.fsid(), crumb_id.index(), metadata.inode.fsid(), metadata.inode.index(), metadata.mode, metadata.size);
  464. #endif
  465. error = -ENOTDIR;
  466. return { };
  467. }
  468. if (!metadata.may_execute(*current)) {
  469. error = -EACCES;
  470. return { };
  471. }
  472. auto parent = crumb_id;
  473. crumb_id = crumb_inode->lookup(part);
  474. if (!crumb_id.is_valid()) {
  475. #ifdef VFS_DEBUG
  476. kprintf("child <%s>(%u) not found in directory, %02u:%08u\n", part.characters(), part.length(), parent.fsid(), parent.index());
  477. #endif
  478. error = -ENOENT;
  479. return { };
  480. }
  481. #ifdef VFS_DEBUG
  482. kprintf("<%s> %u:%u\n", part.characters(), crumb_id.fsid(), crumb_id.index());
  483. #endif
  484. if (auto mount = find_mount_for_host(crumb_id)) {
  485. #ifdef VFS_DEBUG
  486. kprintf(" -- is host\n");
  487. #endif
  488. crumb_id = mount->guest();
  489. }
  490. if (inode_was_root_at_head_of_loop && crumb_id.is_root_inode() && !is_vfs_root(crumb_id) && part == "..") {
  491. #ifdef VFS_DEBUG
  492. kprintf(" -- is guest\n");
  493. #endif
  494. auto mount = find_mount_for_guest(crumb_id);
  495. auto dir_inode = get_inode(mount->host());
  496. ASSERT(dir_inode);
  497. crumb_id = dir_inode->lookup("..");
  498. }
  499. crumb_inode = get_inode(crumb_id);
  500. ASSERT(crumb_inode);
  501. metadata = crumb_inode->metadata();
  502. if (metadata.is_directory()) {
  503. if (i != parts.size() - 1) {
  504. if (parent_id)
  505. *parent_id = crumb_id;
  506. }
  507. }
  508. if (metadata.is_symlink()) {
  509. if (i == parts.size() - 1) {
  510. if (options & O_NOFOLLOW) {
  511. error = -ELOOP;
  512. return { };
  513. }
  514. if (options & O_NOFOLLOW_NOERROR)
  515. return crumb_id;
  516. }
  517. crumb_id = resolve_symbolic_link(parent, *crumb_inode, error);
  518. if (!crumb_id.is_valid()) {
  519. kprintf("Symbolic link resolution failed :(\n");
  520. return { };
  521. }
  522. }
  523. }
  524. return crumb_id;
  525. }
  526. VFS::Mount::Mount(InodeIdentifier host, RetainPtr<FS>&& guest_fs)
  527. : m_host(host)
  528. , m_guest(guest_fs->root_inode())
  529. , m_guest_fs(move(guest_fs))
  530. {
  531. }
  532. void VFS::register_device(Device& device)
  533. {
  534. m_devices.set(encoded_device(device.major(), device.minor()), &device);
  535. }
  536. void VFS::unregister_device(Device& device)
  537. {
  538. m_devices.remove(encoded_device(device.major(), device.minor()));
  539. }
  540. Device* VFS::get_device(unsigned major, unsigned minor)
  541. {
  542. auto it = m_devices.find(encoded_device(major, minor));
  543. if (it == m_devices.end())
  544. return nullptr;
  545. return (*it).value;
  546. }
  547. void VFS::for_each_mount(Function<void(const Mount&)> callback) const
  548. {
  549. for (auto& mount : m_mounts) {
  550. callback(*mount);
  551. }
  552. }
  553. void VFS::sync()
  554. {
  555. FS::sync();
  556. }