include/vfs.h File Reference

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Detailed Description

Acess VFS Layer.

The Acess Virtual File System (VFS) provides abstraction of multiple physical filesystems, network storage and devices (both hardware and virtual) to the user.

The core of the VFS is the concept of a VFS Node. A VFS Node represents a "file" in the VFS tree, this can be any sort of file (an ordinary file, a directory, a symbolic link or a device) depending on the bits set in the tVFS_Node::Flags Flags field.

• For more information see "VFS Node Flags"

Go to the source code of this file.

Data Structures
struct	tVFS_Node
	Represents a node (file or directory) in the VFS tree. More...
struct	tVFS_Driver
	VFS Driver (Filesystem) Definition. More...
Defines
#define	VFS_MAXSKIP   ((void*)1024)
	Maximum number of elements that can be skipped in one return.
#define	VFS_SKIP   ((void*)1)
	Skip a single entry in readdir.
#define	VFS_SKIPN(n)   ((void*)(n))
	Skip n entries in readdir.
tVFS_Node Flags
Flag values for tVFS_Node.Flags
#define	VFS_FFLAG_READONLY   0x01
#define	VFS_FFLAG_DIRECTORY   0x02
	Directory Flag.
#define	VFS_FFLAG_SYMLINK   0x04
	Symbolic Link Flag.
#define	VFS_FFLAG_SETUID   0x08
	Set User ID Flag.
#define	VFS_FFLAG_SETGID   0x10
	Set Group ID Flag.
Functions
int	VFS_AddDriver (tVFS_Driver *Info)
	Registers the driver with the DevFS layer.
tVFS_Driver *	VFS_GetFSByName (const char *Name)
tVFS_ACL *	VFS_UnixToAcessACL (Uint Mode, Uint Owner, Uint Group)
	Transforms Unix Permssions into Acess ACLs.
Node Cache
Functions to allow a node to be cached in memory by the VFS These functions store a node for the driver, to prevent it from having to re-generate the node on each call to FindDir. It also allows for fast cleanup when a filesystem is unmounted.
int	Inode_GetHandle (void)
	Gets a unique handle to the Node Cache.
tVFS_Node *	Inode_GetCache (int Handle, Uint64 Inode)
	Gets an inode from the node cache.
tVFS_Node *	Inode_CacheNode (int Handle, tVFS_Node *Node)
	Caches a node in the Node Cache.
void	Inode_UncacheNode (int Handle, Uint64 Inode)
	Dereferences (and removes if needed) a node from the cache.
void	Inode_ClearCache (int Handle)
	Clears the cache for a handle.
Variables
tVFS_Node	NULLNode
	NULL VFS Node (Ignored/Skipped).
Static ACLs
Simple ACLs to aid writing drivers
tVFS_ACL	gVFS_ACL_EveryoneRWX
	Everyone Read/Write/Execute.
tVFS_ACL	gVFS_ACL_EveryoneRW
	Everyone Read/Write.
tVFS_ACL	gVFS_ACL_EveryoneRX
	Everyone Read/Execute.
tVFS_ACL	gVFS_ACL_EveryoneRO
	Everyone Read only.

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Define Documentation

#define VFS_FFLAG_DIRECTORY   0x02

Directory Flag.

This flag marks the tVFS_Node as describing a directory, and says that the tVFS_Node.FindDir, tVFS_Node.ReadDir, tVFS_Node.MkNod and tVFS_Node.Relink function pointers are valid. For a directory the tVFS_Node.Size field contains the number of files within the directory, or -1 for undetermined.

#define VFS_FFLAG_READONLY   0x01

Todo:

Is this still needed

Readonly File

#define VFS_FFLAG_SETGID   0x10

Set Group ID Flag.

Allows an executable file to change it's executing group to the file's owning group. In the case of a directory, it means that all immediate children will inherit the GID of the parent.

#define VFS_FFLAG_SETUID   0x08

Set User ID Flag.

Allows an executable file to change it's executing user to the file's owner. In the case of a directory, it means that all immediate children will inherit the UID of the parent.

#define VFS_FFLAG_SYMLINK   0x04

Symbolic Link Flag.

Marks a file as a symbolic link

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Function Documentation

tVFS_Node * Inode_CacheNode	(	int	Handle,
		tVFS_Node *	Node
	)

Caches a node in the Node Cache.

Parameters:

	Handle	A handle returned by Inode_GetHandle()
	Node	A pointer to the node to be cached (a copy is taken)

Returns:

A pointer to the node in the node cache

void Inode_ClearCache

(

int

Handle

)

Clears the cache for a handle.

Parameters:

Handle

A handle returned by Inode_GetHandle()

tVFS_Node * Inode_GetCache	(	int	Handle,
		Uint64	Inode
	)

Gets an inode from the node cache.

Parameters:

	Handle	A handle returned by Inode_GetHandle()
	Inode	Value of the Inode field of the tVFS_Node you want

Returns:

A pointer to the cached node

int Inode_GetHandle

(

void

)

Gets a unique handle to the Node Cache.

Returns:

A unique handle for use for the rest of the Inode_* functions

int Inode_UncacheNode	(	int	Handle,
		Uint64	Inode
	)

Dereferences (and removes if needed) a node from the cache.

Parameters:

	Handle	A handle returned by Inode_GetHandle()
	Inode	Value of the Inode field of the tVFS_Node you want to remove

int VFS_AddDriver

(

tVFS_Driver *

Info

)

Registers the driver with the DevFS layer.

Parameters:

Info

Driver information structure

tVFS_ACL * VFS_UnixToAcessACL	(	Uint	Mode,
		Uint	Owner,
		Uint	Group
	)

Transforms Unix Permssions into Acess ACLs.

Parameters:

	Mode	Unix RWXrwxRWX mask
	Owner	UID of the file's owner
	Group	GID of the file's owning group

Returns:

An array of 3 Acess ACLs