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;
29 typedef struct sVFS_NodeType tVFS_NodeType;
32 * \name tVFS_Node Flags
33 * \brief Flag values for tVFS_Node.Flags
36 //! \todo Is this still needed
37 #define VFS_FFLAG_READONLY 0x01 //!< Readonly File
39 * \brief Directory Flag
41 * This flag marks the tVFS_Node as describing a directory, and says
42 * that the tVFS_Node.FindDir, tVFS_Node.ReadDir, tVFS_Node.MkNod and
43 * tVFS_Node.Relink function pointers are valid.
44 * For a directory the tVFS_Node.Size field contains the number of files
45 * within the directory, or -1 for undetermined.
47 #define VFS_FFLAG_DIRECTORY 0x02
49 * \brief Symbolic Link Flag
51 * Marks a file as a symbolic link
53 #define VFS_FFLAG_SYMLINK 0x04
55 * \brief Set User ID Flag
57 * Allows an executable file to change it's executing user to the file's
59 * In the case of a directory, it means that all immediate children will
60 * inherit the UID of the parent.
62 #define VFS_FFLAG_SETUID 0x08
64 * \brief Set Group ID Flag
66 * Allows an executable file to change it's executing group to the file's
68 * In the case of a directory, it means that all immediate children will
69 * inherit the GID of the parent.
71 #define VFS_FFLAG_SETGID 0x10
74 * \brief "Don't do Write-Back" Flag
76 * Stops the VFS from calling tVFS_Node.Write on dirty pages when a region
77 * is unmapped. Nice for read-only files and memory-only files (or
78 * pseudo-readonly filesystems)
80 #define VFS_FFLAG_NOWRITEBACK 0x1000
83 * \brief "Dirty Metadata" Flag
85 * Indicates that the node's metadata has been altered since the flag was last
86 * cleared. Tells the driver that it should update the inode at the next flush.
88 #define VFS_FFLAG_DIRTY 0x8000
94 * \brief Represents a node (file or directory) in the VFS tree
96 * This structure provides the VFS with the functions required to read/write
97 * the file (or directory) that it represents.
99 typedef struct sVFS_Node
102 * \brief Functions associated with the node
108 * \brief Fields used by the driver to identify what data this node
112 Uint64 Inode; //!< Inode ID - Must identify the node uniquely if tVFS_Driver.GetNodeFromINode is non-NULL
113 Uint ImplInt; //!< Implementation Usable Integer
114 void *ImplPtr; //!< Implementation Usable Pointer
121 * \brief Stores the misc information about the node
124 int ReferenceCount; //!< Number of times the node is used
126 Uint64 Size; //!< File Size
128 Uint32 Flags; //!< File Flags
131 * \brief Pointer to cached data (FS Specific)
132 * \note The Inode_* functions will free when the node is uncached
139 * \note Provided for the Filesystem driver's use
151 tTime ATime; //!< Last Accessed Time
152 tTime MTime; //!< Last Modified Time
153 tTime CTime; //!< Creation Time
159 * \name Access control
162 tUID UID; //!< ID of Owning User
163 tGID GID; //!< ID of Owning Group
165 int NumACLs; //!< Number of ACL entries
166 tVFS_ACL *ACLs; //!< Access Controll List pointer
172 * \name VFS_Select() fields
173 * \note Used by the VFS internals, drivers should use VFS_Mark*
177 tVFS_SelectList *ReadThreads; //!< Threads waiting to read
179 tVFS_SelectList *WriteThreads; //!< Threads waiting to write
181 tVFS_SelectList *ErrorThreads; //!< Threads waiting for an error
187 * \name VFS_MMap() fields
197 * \brief Functions for a specific node type
202 * \brief Debug name for the type
204 const char *TypeName;
207 * \name Common Functions
208 * \brief Functions that are used no matter the value of .Flags
212 * \brief Reference the node
213 * \param Node Pointer to this node
215 void (*Reference)(struct sVFS_Node *Node);
217 * \brief Close (dereference) the node
218 * \param Node Pointer to this node
220 * Usually .Close is used to write any changes to the node back to
221 * the persistent storage.
223 void (*Close)(struct sVFS_Node *Node);
226 * \brief Send an IO Control
227 * \param Node Pointer to this node
228 * \param Id IOCtl call number
229 * \param Data Pointer to data to pass to the driver
230 * \return Implementation defined
232 int (*IOCtl)(struct sVFS_Node *Node, int Id, void *Data);
239 * \name Buffer Functions
240 * \brief Functions for accessing a buffer-type file (normal file or
246 * \brief Read from the file
247 * \param Node Pointer to this node
248 * \param Offset Byte offset in the file
249 * \param Length Number of bytes to read
250 * \param Buffer Destination for read data
251 * \return Number of bytes read
253 size_t (*Read)(struct sVFS_Node *Node, off_t Offset, size_t Length, void *Buffer);
255 * \brief Write to the file
256 * \param Node Pointer to this node
257 * \param Offset Byte offser in the file
258 * \param Length Number of bytes to write
259 * \param Buffer Source of written data
260 * \return Number of bytes read
262 size_t (*Write)(struct sVFS_Node *Node, off_t Offset, size_t Length, const void *Buffer);
265 * \brief Map a region of a file into memory
266 * \param Node Pointer to this node
267 * \param Offset Start of the region (page aligned)
268 * \param Length Length of the region (page aligned)
269 * \param Dest Location to which to map
270 * \return Boolean Failure
271 * \note If NULL, the VFS implements it using .Read
273 int (*MMap)(struct sVFS_Node *Node, off_t Offset, int Length, void *Dest);
280 * \name Directory Functions
284 * \brief Find an directory entry by name
285 * \param Node Pointer to this node
286 * \param Name Name of the file wanted
287 * \return Pointer to the requested node or NULL if it cannot be found
288 * \note The node returned must be accessable until ::tVFS_Node.Close
289 * is called and ReferenceCount reaches zero.
291 struct sVFS_Node *(*FindDir)(struct sVFS_Node *Node, const char *Name);
294 * \brief Read from a directory
295 * \param Node Pointer to this node
296 * \param Pos Offset in the directory
297 * \return Pointer to the name of the item on the heap (will be freed
298 * by the caller). If the directory end has been reached, NULL
300 * If an item is required to be skipped either &::NULLNode,
301 * ::VFS_SKIP or ::VFS_SKIPN(0...1023) will be returned.
303 char *(*ReadDir)(struct sVFS_Node *Node, int Pos);
306 * \brief Create a node in a directory
307 * \param Node Pointer to this node
308 * \param Name Name of the new child
309 * \param Flags Flags to apply to the new child (directory or symlink)
310 * \return Zero on Success, non-zero on error (see errno.h)
312 int (*MkNod)(struct sVFS_Node *Node, const char *Name, Uint Flags);
315 * \brief Relink (Rename/Remove) a file/directory
316 * \param Node Pointer to this node
317 * \param OldName Name of the item to move/delete
318 * \return Zero on Success, non-zero on error (see errno.h)
320 int (*Unlink)(struct sVFS_Node *Node, const char *OldName);
323 * \brief Link a node to a name
324 * \param Node Pointer to this node (directory)
325 * \param NewName Name for the new link
326 * \param Child Node to create a new link to
327 * \retur Zeron on success, non-zero on error (see errno.h)
329 int (*Link)(struct sVFS_Node *Node, const char *NewName, struct sVFS_Node *Child);
337 * \brief VFS Driver (Filesystem) Definition
339 typedef struct sVFS_Driver
342 * \brief Unique Identifier for this filesystem type
346 * \brief Flags applying to this driver
351 * \brief Detect if a volume is accessible using this driver
352 * \return Boolean success (with higher numbers being higher priority)
354 * E.g. FAT would return 1 as it's the lowest common denominator while ext2 might return 2,
355 * because it can be embedded in a FAT volume (and is a more fully featured filesystem).
357 int (*Detect)(int FD);
360 * \brief Callback to mount a device
362 tVFS_Node *(*InitDevice)(const char *Device, const char **Options);
364 * \brief Callback to unmount a device
366 void (*Unmount)(tVFS_Node *Node);
368 * \brief Retrieve a VFS node from an inode
370 tVFS_Node *(*GetNodeFromINode)(tVFS_Node *RootNode, Uint64 InodeValue);
372 * \brief Used internally (next driver in the chain)
374 struct sVFS_Driver *Next;
378 //! \brief Maximum number of elements that can be skipped in one return
379 #define VFS_MAXSKIP ((void*)1024)
380 //! \brief Skip a single entry in readdir
381 #define VFS_SKIP ((void*)1)
382 //! \brief Skip \a n entries in readdir
383 #define VFS_SKIPN(n) ((void*)(n))
385 extern tVFS_Node NULLNode; //!< NULL VFS Node (Ignored/Skipped)
388 * \brief Simple ACLs to aid writing drivers
391 extern tVFS_ACL gVFS_ACL_EveryoneRWX; //!< Everyone Read/Write/Execute
392 extern tVFS_ACL gVFS_ACL_EveryoneRW; //!< Everyone Read/Write
393 extern tVFS_ACL gVFS_ACL_EveryoneRX; //!< Everyone Read/Execute
394 extern tVFS_ACL gVFS_ACL_EveryoneRO; //!< Everyone Read only
401 * \fn int VFS_AddDriver(tVFS_Driver *Info)
402 * \brief Registers the driver with the DevFS layer
403 * \param Info Driver information structure
405 extern int VFS_AddDriver(tVFS_Driver *Info);
407 * \brief Get the information structure of a driver given its name
408 * \param Name Name of filesystem driver to find
410 extern tVFS_Driver *VFS_GetFSByName(const char *Name);
414 * \brief Prepare a node for use
416 extern void VFS_InitNode(tVFS_Node *Node);
419 * \brief Clean up a node, ready for deletion
420 * \note This should ALWAYS be called before a node is freed, as it
421 * cleans up VFS internal structures.
423 extern void VFS_CleanupNode(tVFS_Node *Node);
426 * \fn tVFS_ACL *VFS_UnixToAcessACL(Uint Mode, Uint Owner, Uint Group)
427 * \brief Transforms Unix Permssions into Acess ACLs
428 * \param Mode Unix RWXrwxRWX mask
429 * \param Owner UID of the file's owner
430 * \param Group GID of the file's owning group
431 * \return An array of 3 Acess ACLs
433 extern tVFS_ACL *VFS_UnixToAcessACL(Uint Mode, Uint Owner, Uint Group);
436 * \brief Flags fro \a TypeFlag of VFS_SelectNode
439 #define VFS_SELECT_READ 0x01
440 #define VFS_SELECT_WRITE 0x02
441 #define VFS_SELECT_ERROR 0x04
447 * \brief Wait for an event on a node
448 * \param Node Node to wait on
449 * \param Type Type of wait
450 * \param Timeout Time to wait (NULL for infinite wait)
451 * \param Name Name to show in debug output
452 * \return Number of nodes that actioned (0 or 1)
454 extern int VFS_SelectNode(tVFS_Node *Node, int Type, tTime *Timeout, const char *Name);
457 * \brief Change the full flag on a node
459 extern int VFS_MarkFull(tVFS_Node *Node, BOOL IsBufferFull);
461 * \brief Alter the space avaliable flag on a node
463 extern int VFS_MarkAvaliable(tVFS_Node *Node, BOOL IsDataAvaliable);
465 * \brief Alter the error flags on a node
467 extern int VFS_MarkError(tVFS_Node *Node, BOOL IsErrorState);
472 * \brief Functions to allow a node to be cached in memory by the VFS
474 * These functions store a node for the driver, to prevent it from having
475 * to re-generate the node on each call to FindDir. It also allows for
476 * fast cleanup when a filesystem is unmounted.
480 * \fn int Inode_GetHandle(void)
481 * \brief Gets a unique handle to the Node Cache
482 * \return A unique handle for use for the rest of the Inode_* functions
484 extern int Inode_GetHandle(void);
486 * \fn tVFS_Node *Inode_GetCache(int Handle, Uint64 Inode)
487 * \brief Gets an inode from the node cache
488 * \param Handle A handle returned by Inode_GetHandle()
489 * \param Inode Value of the Inode field of the ::tVFS_Node you want
490 * \return A pointer to the cached node
492 extern tVFS_Node *Inode_GetCache(int Handle, Uint64 Inode);
494 * \fn tVFS_Node *Inode_CacheNode(int Handle, tVFS_Node *Node)
495 * \brief Caches a node in the Node Cache
496 * \param Handle A handle returned by Inode_GetHandle()
497 * \param Node A pointer to the node to be cached (a copy is taken)
498 * \return A pointer to the node in the node cache
500 extern tVFS_Node *Inode_CacheNode(int Handle, tVFS_Node *Node);
502 * \fn int Inode_UncacheNode(int Handle, Uint64 Inode)
503 * \brief Dereferences (and removes if needed) a node from the cache
504 * \param Handle A handle returned by Inode_GetHandle()
505 * \param Inode Value of the Inode field of the ::tVFS_Node you want to remove
506 * \return -1: Error (not present), 0: Not freed, 1: Freed
508 extern int Inode_UncacheNode(int Handle, Uint64 Inode);
510 * \fn void Inode_ClearCache(int Handle)
511 * \brief Clears the cache for a handle
512 * \param Handle A handle returned by Inode_GetHandle()
514 extern void Inode_ClearCache(int Handle);