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