| // Copyright 2019 The Chromium OS Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef SMBFS_INODE_MAP_H_ |
| #define SMBFS_INODE_MAP_H_ |
| |
| #include <stdint.h> |
| #include <sys/types.h> |
| |
| #include <memory> |
| #include <string> |
| #include <unordered_map> |
| |
| #include <base/files/file_path.h> |
| #include <base/macros.h> |
| |
| namespace smbfs { |
| |
| // Class that synthesizes inode numbers for file paths, and keeps a reference |
| // count for each inode. Inode numbers are never re-used by new paths. |
| class InodeMap { |
| public: |
| explicit InodeMap(ino_t root_inode); |
| ~InodeMap(); |
| |
| // Return an inode for |path| without incrementing the refcount. If |path| |
| // does not have a corresponding inode, create a weak inode with a refcount of |
| // 0. The weak inode will not exist for the purpose of any other function |
| // except GetWeakInode() and IncInodeRef(). Namely, GetPath(inode) will return |
| // the empty path, and PathExists(path) will return false. Future calls to |
| // GetWeakInode() or IncInodeRef() will return the same inode until the inode |
| // is forgotten by calling Forget(). |path| must be an absolute path, and not |
| // contain any relative components (i.e. '.' and '..'). |
| ino_t GetWeakInode(const base::FilePath& path); |
| |
| // Increment the inode refcount for |path| by 1 and return the inode number. |
| // If the inode for |path| is weak (see above), return the same inode and set |
| // its refcount to 1. If |path| does not have a corresponding inode, create a |
| // new one with a refcount of 1. |path| must be an absolute path, and not |
| // contain any relative components (i.e. '.' and '..'). |
| ino_t IncInodeRef(const base::FilePath& path); |
| |
| // Return the path corresponding to the file |inode|. If the inode does not |
| // exist, return the empty path. |
| base::FilePath GetPath(ino_t inode) const; |
| |
| // Return whether or not an inode exists for |path|. |
| bool PathExists(const base::FilePath& path) const; |
| |
| // Update the path corresponding to the file |inode|. The inode must exist and |
| // must not be |root_inode|, and |new_path| must be an absolute path and not |
| // contain any relative components (i.e. '.' and '..'). |
| void UpdatePath(ino_t inode, const base::FilePath& new_path); |
| |
| // Forget |forget_count| reference to |inode|. If the refcount falls to 0, |
| // remove the inode. |forget_count| cannot be greater than the current |
| // refcount of |inode|. Returns true if the inode was removed. |
| bool Forget(ino_t inode, uint64_t forget_count); |
| |
| private: |
| struct Entry; |
| |
| // Returns the Entry for |path|. If no existing entry exists, a new one is |
| // created with a refcount of 0. |
| Entry* GetEntryByPath(const base::FilePath& path); |
| |
| const ino_t root_inode_; |
| ino_t seq_num_; |
| std::unordered_map<ino_t, std::unique_ptr<Entry>> inodes_; |
| std::unordered_map<std::string, Entry*> files_; |
| |
| DISALLOW_IMPLICIT_CONSTRUCTORS(InodeMap); |
| }; |
| |
| } // namespace smbfs |
| |
| #endif // SMBFS_INODE_MAP_H_ |