7 * \brief Acess VFS Layer
9 * The Acess Virtual File System (VFS) provides abstraction of multiple
10 * physical filesystems, network storage and devices (both hardware and
11 * virtual) to the user.
13 * The core of the VFS is the concept of a \ref tVFS_Node "VFS Node".
14 * A VFS Node represents a "file" in the VFS tree, this can be any sort
15 * of file (an ordinary file, a directory, a symbolic link or a device)
16 * depending on the bits set in the \ref tVFS_Node.Flags Flags field.
17 * - For more information see "VFS Node Flags"
25 * \brief Thread list datatype for VFS_Select
27 typedef struct sVFS_SelectList tVFS_SelectList;
30 * \name tVFS_Node Flags
31 * \brief Flag values for tVFS_Node.Flags
34 //! \todo Is this still needed
35 #define VFS_FFLAG_READONLY 0x01 //!< Readonly File
37 * \brief Directory Flag
39 * This flag marks the tVFS_Node as describing a directory, and says
40 * that the tVFS_Node.FindDir, tVFS_Node.ReadDir, tVFS_Node.MkNod and
41 * tVFS_Node.Relink function pointers are valid.
42 * For a directory the tVFS_Node.Size field contains the number of files
43 * within the directory, or -1 for undetermined.
45 #define VFS_FFLAG_DIRECTORY 0x02
47 * \brief Symbolic Link Flag
49 * Marks a file as a symbolic link
51 #define VFS_FFLAG_SYMLINK 0x04
53 * \brief Set User ID Flag
55 * Allows an executable file to change it's executing user to the file's
57 * In the case of a directory, it means that all immediate children will
58 * inherit the UID of the parent.
60 #define VFS_FFLAG_SETUID 0x08
62 * \brief Set Group ID Flag
64 * Allows an executable file to change it's executing group to the file's
66 * In the case of a directory, it means that all immediate children will
67 * inherit the GID of the parent.
69 #define VFS_FFLAG_SETGID 0x10
72 * \brief "Don't do Write-Back" Flag
74 * Stops the VFS from calling tVFS_Node.Write on dirty pages when a region
75 * is unmapped. Nice for read-only files and memory-only files (or
76 * pseudo-readonly filesystems)
78 #define VFS_FFLAG_NOWRITEBACK
84 * \brief Represents a node (file or directory) in the VFS tree
86 * This structure provides the VFS with the functions required to read/write
87 * the file (or directory) that it represents.
89 typedef struct sVFS_Node
93 * \brief Fields used by the driver to identify what data this node
97 Uint64 Inode; //!< Inode ID (Essentially another ImplInt)
98 Uint ImplInt; //!< Implementation Usable Integer
99 void *ImplPtr; //!< Implementation Usable Pointer
106 * \brief Stores the misc information about the node
109 int ReferenceCount; //!< Number of times the node is used
111 Uint64 Size; //!< File Size
113 Uint32 Flags; //!< File Flags
116 * \brief Pointer to cached data (FS Specific)
117 * \note The Inode_* functions will free when the node is uncached
124 * \note Provided for the Filesystem driver's use
136 Sint64 ATime; //!< Last Accessed Time
137 Sint64 MTime; //!< Last Modified Time
138 Sint64 CTime; //!< Creation Time
144 * \name Access control
147 tUID UID; //!< ID of Owning User
148 tGID GID; //!< ID of Owning Group
150 int NumACLs; //!< Number of ACL entries
151 tVFS_ACL *ACLs; //!< Access Controll List pointer
157 * \name VFS_Select() fields
158 * \note Used by the VFS internals, drivers should use VFS_Mark*
162 tVFS_SelectList *ReadThreads; //!< Threads waiting to read
164 tVFS_SelectList *WriteThreads; //!< Threads waiting to write
166 tVFS_SelectList *ErrorThreads; //!< Threads waiting for an error
172 * \name VFS_MMap() fields
181 * \name Common Functions
182 * \brief Functions that are used no matter the value of .Flags
186 * \brief Reference the node
187 * \param Node Pointer to this node
189 void (*Reference)(struct sVFS_Node *Node);
191 * \brief Close (dereference) the node
192 * \param Node Pointer to this node
194 * Usually .Close is used to write any changes to the node back to
195 * the persistent storage.
197 void (*Close)(struct sVFS_Node *Node);
200 * \brief Send an IO Control
201 * \param Node Pointer to this node
202 * \param Id IOCtl call number
203 * \param Data Pointer to data to pass to the driver
204 * \return Implementation defined
206 int (*IOCtl)(struct sVFS_Node *Node, int Id, void *Data);
213 * \name Buffer Functions
214 * \brief Functions for accessing a buffer-type file (normal file or
220 * \brief Read from the file
221 * \param Node Pointer to this node
222 * \param Offset Byte offset in the file
223 * \param Length Number of bytes to read
224 * \param Buffer Destination for read data
225 * \return Number of bytes read
227 Uint64 (*Read)(struct sVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer);
229 * \brief Write to the file
230 * \param Node Pointer to this node
231 * \param Offset Byte offser in the file
232 * \param Length Number of bytes to write
233 * \param Buffer Source of written data
234 * \return Number of bytes read
236 Uint64 (*Write)(struct sVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer);
239 * \brief Map a region of a file into memory
240 * \param Node Pointer to this node
241 * \param Offset Start of the region (page aligned)
242 * \param Length Length of the region (page aligned)
243 * \param Dest Location to which to map
244 * \return Boolean Failure
245 * \note If NULL, the VFS implements it using .Read
247 int (*MMap)(struct sVFS_Node *Node, Uint64 Offset, int Length, void *Dest);
254 * \name Directory Functions
258 * \brief Find an directory entry by name
259 * \param Node Pointer to this node
260 * \param Name Name of the file wanted
261 * \return Pointer to the requested node or NULL if it cannot be found
262 * \note The node returned must be accessable until ::tVFS_Node.Close
263 * is called and ReferenceCount reaches zero.
265 struct sVFS_Node *(*FindDir)(struct sVFS_Node *Node, const char *Name);
268 * \brief Read from a directory
269 * \param Node Pointer to this node
270 * \param Pos Offset in the directory
271 * \return Pointer to the name of the item on the heap (will be freed
272 * by the caller). If the directory end has been reached, NULL
274 * If an item is required to be skipped either &::NULLNode,
275 * ::VFS_SKIP or ::VFS_SKIPN(0...1023) will be returned.
277 char *(*ReadDir)(struct sVFS_Node *Node, int Pos);
280 * \brief Create a node in a directory
281 * \param Node Pointer to this node
282 * \param Name Name of the new child
283 * \param Flags Flags to apply to the new child (directory or symlink)
284 * \return Zero on Success, non-zero on error (see errno.h)
286 int (*MkNod)(struct sVFS_Node *Node, const char *Name, Uint Flags);
289 * \brief Relink (Rename/Remove) a file/directory
290 * \param Node Pointer to this node
291 * \param OldName Name of the item to move/delete
292 * \param NewName New name (or NULL if unlinking is wanted)
293 * \return Zero on Success, non-zero on error (see errno.h)
295 int (*Relink)(struct sVFS_Node *Node, const char *OldName, const char *NewName);
298 * \brief Link a node to a name
299 * \param Node Pointer to this node (directory)
300 * \param Child Node to create a new link to
301 * \param NewName Name for the new link
302 * \return Zeron on success, non-zero on error (see errno.h)
304 int (*Link)(struct sVFS_Node *Node, struct sVFS_Node *Child, const char *NewName);
312 * \brief VFS Driver (Filesystem) Definition
314 typedef struct sVFS_Driver
316 //! \brief Unique Identifier for this filesystem type
318 //! \brief Flags applying to this driver
321 //! \brief Callback to mount a device
322 tVFS_Node *(*InitDevice)(const char *Device, const char **Options);
323 //! \brief Callback to unmount a device
324 void (*Unmount)(tVFS_Node *Node);
325 //! \brief Used internally (next driver in the chain)
326 struct sVFS_Driver *Next;
330 //! \brief Maximum number of elements that can be skipped in one return
331 #define VFS_MAXSKIP ((void*)1024)
332 //! \brief Skip a single entry in readdir
333 #define VFS_SKIP ((void*)1)
334 //! \brief Skip \a n entries in readdir
335 #define VFS_SKIPN(n) ((void*)(n))
337 extern tVFS_Node NULLNode; //!< NULL VFS Node (Ignored/Skipped)
340 * \brief Simple ACLs to aid writing drivers
343 extern tVFS_ACL gVFS_ACL_EveryoneRWX; //!< Everyone Read/Write/Execute
344 extern tVFS_ACL gVFS_ACL_EveryoneRW; //!< Everyone Read/Write
345 extern tVFS_ACL gVFS_ACL_EveryoneRX; //!< Everyone Read/Execute
346 extern tVFS_ACL gVFS_ACL_EveryoneRO; //!< Everyone Read only
353 * \fn int VFS_AddDriver(tVFS_Driver *Info)
354 * \brief Registers the driver with the DevFS layer
355 * \param Info Driver information structure
357 extern int VFS_AddDriver(tVFS_Driver *Info);
359 * \fn tVFS_Driver *VFS_GetFSByName(char *Name)
360 * \brief Get the information structure of a driver given its name
361 * \param Name Name of filesystem driver to find
363 extern tVFS_Driver *VFS_GetFSByName(const char *Name);
367 * \brief Prepare a node for use
369 extern void VFS_InitNode(tVFS_Node *Node);
372 * \brief Clean up a node, ready for deletion
373 * \note This should ALWAYS be called before a node is freed, as it
374 * cleans up VFS internal structures.
376 extern void VFS_CleanupNode(tVFS_Node *Node);
379 * \fn tVFS_ACL *VFS_UnixToAcessACL(Uint Mode, Uint Owner, Uint Group)
380 * \brief Transforms Unix Permssions into Acess ACLs
381 * \param Mode Unix RWXrwxRWX mask
382 * \param Owner UID of the file's owner
383 * \param Group GID of the file's owning group
384 * \return An array of 3 Acess ACLs
386 extern tVFS_ACL *VFS_UnixToAcessACL(Uint Mode, Uint Owner, Uint Group);
389 * \brief Flags fro \a TypeFlag of VFS_SelectNode
392 #define VFS_SELECT_READ 0x01
393 #define VFS_SELECT_WRITE 0x02
394 #define VFS_SELECT_ERROR 0x04
400 * \brief Wait for an event on a node
401 * \param Node Node to wait on
402 * \param Type Type of wait
403 * \param Timeout Time to wait (NULL for infinite wait)
404 * \param Name Name to show in debug output
405 * \return Number of nodes that actioned (0 or 1)
407 extern int VFS_SelectNode(tVFS_Node *Node, int Type, tTime *Timeout, const char *Name);
410 * \brief Change the full flag on a node
412 extern int VFS_MarkFull(tVFS_Node *Node, BOOL IsBufferFull);
413 extern int VFS_MarkAvaliable(tVFS_Node *Node, BOOL IsDataAvaliable);
414 extern int VFS_MarkError(tVFS_Node *Node, BOOL IsErrorState);
419 * \brief Functions to allow a node to be cached in memory by the VFS
421 * These functions store a node for the driver, to prevent it from having
422 * to re-generate the node on each call to FindDir. It also allows for
423 * fast cleanup when a filesystem is unmounted.
427 * \fn int Inode_GetHandle(void)
428 * \brief Gets a unique handle to the Node Cache
429 * \return A unique handle for use for the rest of the Inode_* functions
431 extern int Inode_GetHandle(void);
433 * \fn tVFS_Node *Inode_GetCache(int Handle, Uint64 Inode)
434 * \brief Gets an inode from the node cache
435 * \param Handle A handle returned by Inode_GetHandle()
436 * \param Inode Value of the Inode field of the ::tVFS_Node you want
437 * \return A pointer to the cached node
439 extern tVFS_Node *Inode_GetCache(int Handle, Uint64 Inode);
441 * \fn tVFS_Node *Inode_CacheNode(int Handle, tVFS_Node *Node)
442 * \brief Caches a node in the Node Cache
443 * \param Handle A handle returned by Inode_GetHandle()
444 * \param Node A pointer to the node to be cached (a copy is taken)
445 * \return A pointer to the node in the node cache
447 extern tVFS_Node *Inode_CacheNode(int Handle, tVFS_Node *Node);
449 * \fn int Inode_UncacheNode(int Handle, Uint64 Inode)
450 * \brief Dereferences (and removes if needed) a node from the cache
451 * \param Handle A handle returned by Inode_GetHandle()
452 * \param Inode Value of the Inode field of the ::tVFS_Node you want to remove
454 extern void Inode_UncacheNode(int Handle, Uint64 Inode);
456 * \fn void Inode_ClearCache(int Handle)
457 * \brief Clears the cache for a handle
458 * \param Handle A handle returned by Inode_GetHandle()
460 extern void Inode_ClearCache(int Handle);