TmpFS.cpp 9.3 KB

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  1. /*
  2. * Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
  3. *
  4. * SPDX-License-Identifier: BSD-2-Clause
  5. */
  6. #include <Kernel/FileSystem/TmpFS.h>
  7. #include <Kernel/Process.h>
  8. #include <Kernel/Thread.h>
  9. #include <LibC/limits.h>
  10. namespace Kernel {
  11. RefPtr<TmpFS> TmpFS::create()
  12. {
  13. return adopt_ref_if_nonnull(new (nothrow) TmpFS);
  14. }
  15. TmpFS::TmpFS()
  16. {
  17. }
  18. TmpFS::~TmpFS()
  19. {
  20. }
  21. bool TmpFS::initialize()
  22. {
  23. m_root_inode = TmpFSInode::create_root(*this);
  24. return !m_root_inode.is_null();
  25. }
  26. NonnullRefPtr<Inode> TmpFS::root_inode() const
  27. {
  28. VERIFY(!m_root_inode.is_null());
  29. return *m_root_inode;
  30. }
  31. void TmpFS::register_inode(TmpFSInode& inode)
  32. {
  33. Locker locker(m_lock);
  34. VERIFY(inode.identifier().fsid() == fsid());
  35. auto index = inode.identifier().index();
  36. m_inodes.set(index, inode);
  37. }
  38. void TmpFS::unregister_inode(InodeIdentifier identifier)
  39. {
  40. Locker locker(m_lock);
  41. VERIFY(identifier.fsid() == fsid());
  42. m_inodes.remove(identifier.index());
  43. }
  44. unsigned TmpFS::next_inode_index()
  45. {
  46. Locker locker(m_lock);
  47. return m_next_inode_index++;
  48. }
  49. RefPtr<Inode> TmpFS::get_inode(InodeIdentifier identifier) const
  50. {
  51. Locker locker(m_lock, Mutex::Mode::Shared);
  52. VERIFY(identifier.fsid() == fsid());
  53. auto it = m_inodes.find(identifier.index());
  54. if (it == m_inodes.end())
  55. return nullptr;
  56. return it->value;
  57. }
  58. TmpFSInode::TmpFSInode(TmpFS& fs, InodeMetadata metadata, InodeIdentifier parent)
  59. : Inode(fs, fs.next_inode_index())
  60. , m_metadata(metadata)
  61. , m_parent(parent)
  62. {
  63. m_metadata.inode = identifier();
  64. }
  65. TmpFSInode::~TmpFSInode()
  66. {
  67. }
  68. RefPtr<TmpFSInode> TmpFSInode::create(TmpFS& fs, InodeMetadata metadata, InodeIdentifier parent)
  69. {
  70. auto inode = adopt_ref_if_nonnull(new (nothrow) TmpFSInode(fs, metadata, parent));
  71. if (inode)
  72. fs.register_inode(*inode);
  73. return inode;
  74. }
  75. RefPtr<TmpFSInode> TmpFSInode::create_root(TmpFS& fs)
  76. {
  77. InodeMetadata metadata;
  78. auto now = kgettimeofday().to_truncated_seconds();
  79. metadata.atime = now;
  80. metadata.ctime = now;
  81. metadata.mtime = now;
  82. metadata.mode = S_IFDIR | S_ISVTX | 0777;
  83. return create(fs, metadata, { fs.fsid(), 1 });
  84. }
  85. InodeMetadata TmpFSInode::metadata() const
  86. {
  87. Locker locker(m_lock, Mutex::Mode::Shared);
  88. return m_metadata;
  89. }
  90. KResult TmpFSInode::traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
  91. {
  92. Locker locker(m_lock, Mutex::Mode::Shared);
  93. if (!is_directory())
  94. return ENOTDIR;
  95. callback({ ".", identifier(), 0 });
  96. callback({ "..", m_parent, 0 });
  97. for (auto& it : m_children) {
  98. auto& entry = it.value;
  99. callback({ entry.name, entry.inode->identifier(), 0 });
  100. }
  101. return KSuccess;
  102. }
  103. KResultOr<size_t> TmpFSInode::read_bytes(off_t offset, size_t size, UserOrKernelBuffer& buffer, FileDescription*) const
  104. {
  105. Locker locker(m_lock, Mutex::Mode::Shared);
  106. VERIFY(!is_directory());
  107. VERIFY(offset >= 0);
  108. if (!m_content)
  109. return 0;
  110. if (offset >= m_metadata.size)
  111. return 0;
  112. if (static_cast<off_t>(size) > m_metadata.size - offset)
  113. size = m_metadata.size - offset;
  114. if (!buffer.write(m_content->data() + offset, size))
  115. return EFAULT;
  116. return size;
  117. }
  118. KResultOr<size_t> TmpFSInode::write_bytes(off_t offset, size_t size, const UserOrKernelBuffer& buffer, FileDescription*)
  119. {
  120. Locker locker(m_lock);
  121. VERIFY(!is_directory());
  122. VERIFY(offset >= 0);
  123. auto result = prepare_to_write_data();
  124. if (result.is_error())
  125. return result;
  126. off_t old_size = m_metadata.size;
  127. off_t new_size = m_metadata.size;
  128. if (static_cast<off_t>(offset + size) > new_size)
  129. new_size = offset + size;
  130. if (static_cast<u64>(new_size) > (NumericLimits<size_t>::max() / 2)) // on 32-bit, size_t might be 32 bits while off_t is 64 bits
  131. return ENOMEM; // we won't be able to resize to this capacity
  132. if (new_size > old_size) {
  133. if (m_content && static_cast<off_t>(m_content->capacity()) >= new_size) {
  134. m_content->set_size(new_size);
  135. } else {
  136. // Grow the content buffer 2x the new sizeto accommodate repeating write() calls.
  137. // Note that we're not actually committing physical memory to the buffer
  138. // until it's needed. We only grow VM here.
  139. // FIXME: Fix this so that no memcpy() is necessary, and we can just grow the
  140. // KBuffer and it will add physical pages as needed while keeping the
  141. // existing ones.
  142. auto tmp = KBuffer::try_create_with_size(new_size * 2);
  143. if (!tmp)
  144. return ENOMEM;
  145. tmp->set_size(new_size);
  146. if (m_content)
  147. memcpy(tmp->data(), m_content->data(), old_size);
  148. m_content = move(tmp);
  149. }
  150. m_metadata.size = new_size;
  151. set_metadata_dirty(true);
  152. set_metadata_dirty(false);
  153. }
  154. if (!buffer.read(m_content->data() + offset, size)) // TODO: partial reads?
  155. return EFAULT;
  156. did_modify_contents();
  157. return size;
  158. }
  159. RefPtr<Inode> TmpFSInode::lookup(StringView name)
  160. {
  161. Locker locker(m_lock, Mutex::Mode::Shared);
  162. VERIFY(is_directory());
  163. if (name == ".")
  164. return this;
  165. if (name == "..")
  166. return fs().get_inode(m_parent);
  167. auto it = m_children.find(name);
  168. if (it == m_children.end())
  169. return {};
  170. return fs().get_inode(it->value.inode->identifier());
  171. }
  172. KResultOr<size_t> TmpFSInode::directory_entry_count() const
  173. {
  174. Locker locker(m_lock, Mutex::Mode::Shared);
  175. VERIFY(is_directory());
  176. return 2 + m_children.size();
  177. }
  178. void TmpFSInode::notify_watchers()
  179. {
  180. set_metadata_dirty(true);
  181. set_metadata_dirty(false);
  182. }
  183. void TmpFSInode::flush_metadata()
  184. {
  185. // We don't really have any metadata that could become dirty.
  186. // The only reason we even call set_metadata_dirty() is
  187. // to let the watchers know we have updates. Once that is
  188. // switched to a different mechanism, we can stop ever marking
  189. // our metadata as dirty at all.
  190. set_metadata_dirty(false);
  191. }
  192. KResult TmpFSInode::chmod(mode_t mode)
  193. {
  194. Locker locker(m_lock);
  195. m_metadata.mode = mode;
  196. notify_watchers();
  197. return KSuccess;
  198. }
  199. KResult TmpFSInode::chown(uid_t uid, gid_t gid)
  200. {
  201. Locker locker(m_lock);
  202. m_metadata.uid = uid;
  203. m_metadata.gid = gid;
  204. notify_watchers();
  205. return KSuccess;
  206. }
  207. KResultOr<NonnullRefPtr<Inode>> TmpFSInode::create_child(const String& name, mode_t mode, dev_t dev, uid_t uid, gid_t gid)
  208. {
  209. Locker locker(m_lock);
  210. // TODO: Support creating devices on TmpFS.
  211. if (dev != 0)
  212. return ENOTSUP;
  213. time_t now = kgettimeofday().to_truncated_seconds();
  214. InodeMetadata metadata;
  215. metadata.mode = mode;
  216. metadata.uid = uid;
  217. metadata.gid = gid;
  218. metadata.atime = now;
  219. metadata.ctime = now;
  220. metadata.mtime = now;
  221. auto child = TmpFSInode::create(fs(), metadata, identifier());
  222. if (!child)
  223. return ENOMEM;
  224. auto result = add_child(*child, name, mode);
  225. if (result.is_error())
  226. return result;
  227. return child.release_nonnull();
  228. }
  229. KResult TmpFSInode::add_child(Inode& child, const StringView& name, mode_t)
  230. {
  231. Locker locker(m_lock);
  232. VERIFY(is_directory());
  233. VERIFY(child.fsid() == fsid());
  234. if (name.length() > NAME_MAX)
  235. return ENAMETOOLONG;
  236. m_children.set(name, { name, static_cast<TmpFSInode&>(child) });
  237. did_add_child(child.identifier(), name);
  238. return KSuccess;
  239. }
  240. KResult TmpFSInode::remove_child(const StringView& name)
  241. {
  242. Locker locker(m_lock);
  243. VERIFY(is_directory());
  244. if (name == "." || name == "..")
  245. return KSuccess;
  246. auto it = m_children.find(name);
  247. if (it == m_children.end())
  248. return ENOENT;
  249. auto child_id = it->value.inode->identifier();
  250. it->value.inode->did_delete_self();
  251. m_children.remove(it);
  252. did_remove_child(child_id, name);
  253. return KSuccess;
  254. }
  255. KResult TmpFSInode::truncate(u64 size)
  256. {
  257. Locker locker(m_lock);
  258. VERIFY(!is_directory());
  259. if (size == 0)
  260. m_content.clear();
  261. else if (!m_content) {
  262. m_content = KBuffer::try_create_with_size(size);
  263. if (!m_content)
  264. return ENOMEM;
  265. } else if (static_cast<size_t>(size) < m_content->capacity()) {
  266. size_t prev_size = m_metadata.size;
  267. m_content->set_size(size);
  268. if (prev_size < static_cast<size_t>(size))
  269. memset(m_content->data() + prev_size, 0, size - prev_size);
  270. } else {
  271. size_t prev_size = m_metadata.size;
  272. auto tmp = KBuffer::try_create_with_size(size);
  273. if (!tmp)
  274. return ENOMEM;
  275. memcpy(tmp->data(), m_content->data(), prev_size);
  276. m_content = move(tmp);
  277. }
  278. m_metadata.size = size;
  279. notify_watchers();
  280. return KSuccess;
  281. }
  282. KResult TmpFSInode::set_atime(time_t time)
  283. {
  284. Locker locker(m_lock);
  285. m_metadata.atime = time;
  286. set_metadata_dirty(true);
  287. set_metadata_dirty(false);
  288. return KSuccess;
  289. }
  290. KResult TmpFSInode::set_ctime(time_t time)
  291. {
  292. Locker locker(m_lock);
  293. m_metadata.ctime = time;
  294. notify_watchers();
  295. return KSuccess;
  296. }
  297. KResult TmpFSInode::set_mtime(time_t t)
  298. {
  299. Locker locker(m_lock);
  300. m_metadata.mtime = t;
  301. notify_watchers();
  302. return KSuccess;
  303. }
  304. void TmpFSInode::one_ref_left()
  305. {
  306. // Destroy ourselves.
  307. fs().unregister_inode(identifier());
  308. }
  309. }