vfs.h File Reference

Virtual file system: device nodes, RAM files and directories, mounted filesystems, paths, and descriptors. More...

#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>

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Data Structures
struct	vfs_ops_t
	Device operations. More...
struct	vfs_node
	Named entry in the VFS namespace. More...
struct	vfs_stat_t
	File type and size reported by vfs_stat() and vfs_fstat(). More...
struct	vfs_fs_ops_t
	Operations a mounted filesystem provides; every one is required. More...

Macros
Limits
#define	VFS_SNAPSHOT_CAPACITY   32
	Maximum content size of a snapshot device, in bytes.
#define	VFS_PATH_CAPACITY   128
	Path buffer size including the terminator; paths hold at most 127 bytes.

Functions
Descriptor operations
int	vfs_open (const char *name, int flags)
	Open a node and allocate the lowest free descriptor.
int	vfs_close (int fd)
	Release a descriptor.
int	vfs_read (int fd, void *buf, unsigned len)
	Read from a descriptor.
int	vfs_write (int fd, const void *buf, unsigned len)
	Write to a descriptor.
int	vfs_ioctl (int fd, unsigned request, void *arg)
	Forward a control request to a device.
int	vfs_lseek (int fd, int offset, int whence)
	Move a descriptor's position.
vfs_node_t *	vfs_fd_node (int fd)
	Get the node behind an open descriptor.
int	vfs_stat (const char *path, vfs_stat_t *stat)
	Report the type and size of a path.
int	vfs_fstat (int fd, vfs_stat_t *stat)
	Report the type and size of an open descriptor.
Mounted filesystems
A mounted filesystem owns everything below its mount point. Paths passed to its operations are relative to the mount point and always start with / (the mount point itself is /). Operations return 0 or a byte count on success and -1 with errno set on failure, like the corresponding vfs_* functions. The VFS resolves . and .., rejects reads and writes the access mode forbids, zero-length transfers, and NULL buffers, and allocates the descriptor; the filesystem handles O_CREAT, O_EXCL, O_TRUNC, and O_APPEND. Descriptors on mounted files do not support vfs_ioctl() (ENOTTY).
int	vfs_mount (const char *path, const vfs_fs_ops_t *ops, void *fs)
	Attach a filesystem at a new mount point.

Nodes and drivers
typedef struct vfs_node	vfs_node_t
	VFS node; see struct vfs_node.
void	vfs_init (void)
	Obsolete initializer; currently does nothing.
void	vfs_register_node (vfs_node_t *node)
	Add a node to the namespace.
vfs_node_t *	vfs_find_node (const char *name)
	Look up a node by path.

Namespace operations
typedef int(*	vfs_directory_visitor_t) (const char *name, bool is_directory, void *context)
	Visitor called for each directory entry by vfs_list().
int	vfs_resolve_path (const char *base, const char *path, char result[VFS_PATH_CAPACITY])
	Resolve a path against an explicit base directory.
int	vfs_mkdir (const char *path)
	Create an empty directory.
int	vfs_rmdir (const char *path)
	Remove an empty directory created by vfs_mkdir().
int	vfs_unlink (const char *path)
	Remove a file: a RAM file, whose contents are freed, or a file on a mounted filesystem.
int	vfs_list (const char *path, vfs_directory_visitor_t visitor, void *context)
	Visit the direct children of a directory.

Detailed Description

Virtual file system: device nodes, RAM files and directories, mounted filesystems, paths, and descriptors.