In-Memory File System Support

In-Memory File System Support. More...

Modules
	IMFS Device IO Handler

Files
file	deviceio.c
	IMFS Device Node Handlers.
file	imfs_chown.c
	IMFS Change Owner.
file	imfs_config.c
	IMFS Limits and Options.
file	imfs_creat.c
	Create an IMFS Node.
file	imfs_dir.c
file	imfs_dir_default.c
file	imfs_dir_minimal.c
file	imfs_eval.c
	Evaluation IMFS Node Support.
file	imfs_fchmod.c
	Change IMFS File Mode.
file	imfs_fifo.c
	FIFO Support.
file	imfs_fsunmount.c
	Unmount this Instance of IMFS.
file	imfs_handlers_device.c
	Device Operations Table.
file	imfs_initsupp.c
	IMFS Node Support.
file	imfs_linfile.c
file	imfs_link.c
	IMFS Create a New Link Node.
file	imfs_load_tar.c
	RTEMS Load Tarfs.
file	imfs_make_generic_node.c
	IMFS Make a Generic Node.
file	imfs_memfile.c
	IMFS Memory File Handlers.
file	imfs_mknod.c
	Create a IMFS Node.
file	imfs_mount.c
	Mount an IMFS.
file	imfs_node.c
	IMFS Node Support.
file	imfs_rename.c
	IMFS Rename.
file	imfs_rmnod.c
	IMFS Node Removal Handler.
file	imfs_stat.c
	IMFS Stat.
file	imfs_stat_file.c
file	imfs_symlink.c
	IMFS Create a New Symbolic Link Node.
file	imfs_unmount.c
	Unmount an IMFS.
file	imfs_utime.c
	Set IMFS File Access and Modification Times.

Data Structures
struct	IMFS_jnode_tt
struct	IMFS_directory_t
struct	IMFS_device_t
struct	IMFS_link_t
struct	IMFS_sym_link_t
struct	IMFS_filebase_t
struct	IMFS_memfile_t
struct	IMFS_linearfile_t
union	IMFS_file_t
struct	IMFS_fifo_t
struct	IMFS_generic_t
struct	IMFS_mknod_controls
struct	IMFS_fs_info_t
struct	IMFS_mount_data

Macros
#define	IMFS_MEMFILE_DEFAULT_BYTES_PER_BLOCK   128
#define	IMFS_MEMFILE_BYTES_PER_BLOCK   imfs_memfile_bytes_per_block
#define	IMFS_MEMFILE_BLOCK_SLOTS   (IMFS_MEMFILE_BYTES_PER_BLOCK / sizeof(void *))
#define	FIRST_INDIRECT   (0)
#define	LAST_INDIRECT   (IMFS_MEMFILE_BLOCK_SLOTS - 1)
#define	FIRST_DOUBLY_INDIRECT   (LAST_INDIRECT + 1)
#define	LAST_DOUBLY_INDIRECT
#define	FIRST_TRIPLY_INDIRECT   (LAST_DOUBLY_INDIRECT + 1)
#define	LAST_TRIPLY_INDIRECT
#define	IMFS_MEMFILE_MAXIMUM_SIZE   (LAST_TRIPLY_INDIRECT * IMFS_MEMFILE_BYTES_PER_BLOCK)
#define	IMFS_NAME_MAX   _POSIX_NAME_MAX
#define	IMFS_NODE_FLAG_NAME_ALLOCATED   0x1
#define	IMFS_assert(_x)
#define	IMFS_STAT_FMT_HARD_LINK   0

Typedefs
typedef struct IMFS_jnode_tt	IMFS_jnode_t
typedef uint8_t *	block_p
typedef block_p *	block_ptr

Functions
int	IMFS_initialize (rtems_filesystem_mount_table_entry_t *mt_entry, const void *data)
int	IMFS_initialize_support (rtems_filesystem_mount_table_entry_t *mt_entry, const void *data)
void	IMFS_fsunmount (rtems_filesystem_mount_table_entry_t *mt_entry)
	Unmount this instance of IMFS.
int	rtems_tarfs_load (const char *mountpoint, uint8_t *tar_image, size_t tar_size)
	RTEMS load tarfs. More...
void	IMFS_node_destroy (IMFS_jnode_t *node)
	Destroy an IMFS node.
int	IMFS_node_clone (rtems_filesystem_location_info_t *loc)
	Clone an IMFS node.
void	IMFS_node_free (const rtems_filesystem_location_info_t *loc)
	Free an IMFS node.
int	IMFS_stat (const rtems_filesystem_location_info_t *loc, struct stat *buf)
	Perform a status processing for the IMFS. More...
int	IMFS_stat_file (const rtems_filesystem_location_info_t *loc, struct stat *buf)
void	IMFS_eval_path (rtems_filesystem_eval_path_context_t *ctx)
	IMFS evaluation node support.
int	IMFS_link (const rtems_filesystem_location_info_t *parentloc, const rtems_filesystem_location_info_t *targetloc, const char *name, size_t namelen)
	Create a new IMFS link node. More...
int	IMFS_chown (const rtems_filesystem_location_info_t *loc, uid_t owner, gid_t group)
	Change the owner of IMFS. More...
int	IMFS_mknod (const rtems_filesystem_location_info_t *parentloc, const char *name, size_t namelen, mode_t mode, dev_t dev)
	Create an IMFS node. More...
IMFS_jnode_t *	IMFS_initialize_node (IMFS_jnode_t *node, const IMFS_node_control *node_control, const char *name, size_t namelen, mode_t mode, void *arg)
IMFS_jnode_t *	IMFS_create_node (const rtems_filesystem_location_info_t *parentloc, const IMFS_node_control *node_control, size_t node_size, const char *name, size_t namelen, mode_t mode, void *arg)
	Create an IMFS node. More...
int	IMFS_mount (rtems_filesystem_mount_table_entry_t *mt_entry)
	Mount an IMFS.
int	IMFS_unmount (rtems_filesystem_mount_table_entry_t *mt_entry)
	Unmount an IMFS.
int	IMFS_utime (const rtems_filesystem_location_info_t *loc, time_t actime, time_t modtime)
	Set IMFS file access and modification times. More...
int	IMFS_fchmod (const rtems_filesystem_location_info_t *loc, mode_t mode)
	Change the IMFS file mode.
int	IMFS_symlink (const rtems_filesystem_location_info_t *parentloc, const char *name, size_t namelen, const char *target)
	Create a new IMFS symbolic link node. More...
ssize_t	IMFS_readlink (const rtems_filesystem_location_info_t *loc, char *buf, size_t bufsize)
	Put IMFS symbolic link into buffer. More...
int	IMFS_rename (const rtems_filesystem_location_info_t *oldparentloc, const rtems_filesystem_location_info_t *oldloc, const rtems_filesystem_location_info_t *newparentloc, const char *name, size_t namelen)
	Rename the IMFS. More...
int	IMFS_rmnod (const rtems_filesystem_location_info_t *parentloc, const rtems_filesystem_location_info_t *loc)
	IMFS node removal handler. More...

Variables
int	imfs_rq_memfile_bytes_per_block
int	imfs_memfile_bytes_per_block
const IMFS_mknod_control	IMFS_mknod_control_dir_default
const IMFS_mknod_control	IMFS_mknod_control_dir_minimal
const IMFS_mknod_control	IMFS_mknod_control_device
const IMFS_mknod_control	IMFS_mknod_control_memfile
const IMFS_node_control	IMFS_node_control_linfile
const IMFS_mknod_control	IMFS_mknod_control_fifo
const IMFS_mknod_control	IMFS_mknod_control_enosys
const rtems_filesystem_limits_and_options_t	IMFS_LIMITS_AND_OPTIONS

IMFS Memory File Handlers
This section contains the set of handlers used to process operations on IMFS memory file nodes. The memory files are created in memory using malloc'ed memory. Thus any data stored in one of these files is lost at system shutdown unless special arrangements to copy the data to some type of non-volailte storage are made by the application.
ssize_t	IMFS_memfile_write (IMFS_memfile_t *memfile, off_t start, const unsigned char *source, unsigned int length)

IMFS Device Node Handlers
This section contains the set of handlers used to map operations on IMFS device nodes onto calls to the RTEMS Classic API IO Manager.
int	device_open (rtems_libio_t *iop, const char *pathname, int oflag, mode_t mode)
int	device_close (rtems_libio_t *iop)
ssize_t	device_read (rtems_libio_t *iop, void *buffer, size_t count)
ssize_t	device_write (rtems_libio_t *iop, const void *buffer, size_t count)
int	device_ioctl (rtems_libio_t *iop, ioctl_command_t command, void *buffer)
int	device_ftruncate (rtems_libio_t *iop, off_t length)

Detailed Description

In-Memory File System Support.

Macro Definition Documentation

IMFS_MEMFILE_DEFAULT_BYTES_PER_BLOCK

#define IMFS_MEMFILE_DEFAULT_BYTES_PER_BLOCK   128

IMFS "memfile" information

The data structure for the in-memory "memfiles" is based on classic UNIX.

block_ptr is a pointer to a block of IMFS_MEMFILE_BYTES_PER_BLOCK in length which could be data or a table of pointers to blocks.

Setting IMFS_MEMFILE_BYTES_PER_BLOCK to different values has a significant impact on the maximum file size supported as well as the amount of memory wasted due to internal file fragmentation. The following is a list of maximum file sizes based on various settings

max_filesize with blocks of   16 is         1,328
max_filesize with blocks of   32 is        18,656
max_filesize with blocks of   64 is       279,488
max_filesize with blocks of  128 is     4,329,344
max_filesize with blocks of  256 is    68,173,568
max_filesize with blocks of  512 is 1,082,195,456

LAST_DOUBLY_INDIRECT

#define LAST_DOUBLY_INDIRECT

Value:

(LAST_INDIRECT + \
     (IMFS_MEMFILE_BLOCK_SLOTS * IMFS_MEMFILE_BLOCK_SLOTS))

LAST_TRIPLY_INDIRECT

#define LAST_TRIPLY_INDIRECT

Value:

(LAST_DOUBLY_INDIRECT +\
     (IMFS_MEMFILE_BLOCK_SLOTS * \
        IMFS_MEMFILE_BLOCK_SLOTS * IMFS_MEMFILE_BLOCK_SLOTS))

Function Documentation

IMFS_chown()

int IMFS_chown	(	const rtems_filesystem_location_info_t *	loc,
		uid_t	owner,
		gid_t	group
	)

Change the owner of IMFS.

This routine is the implementation of the chown() system call for the IMFS.

IMFS_create_node()

IMFS_jnode_t* IMFS_create_node	(	const rtems_filesystem_location_info_t *	parentloc,
		const IMFS_node_control *	node_control,
		size_t	node_size,
		const char *	name,
		size_t	namelen,
		mode_t	mode,
		void *	arg
	)

Create an IMFS node.

Create an IMFS filesystem node of an arbitrary type that is NOT the root directory node.

IMFS_link()

int IMFS_link	(	const rtems_filesystem_location_info_t *	parentloc,
		const rtems_filesystem_location_info_t *	targetloc,
		const char *	name,
		size_t	namelen
	)

Create a new IMFS link node.

The following rouine creates a new link node under parent with the name given in name. The link node is set to point to the node at to_loc.

IMFS_mknod()

int IMFS_mknod	(	const rtems_filesystem_location_info_t *	parentloc,
		const char *	name,
		size_t	namelen,
		mode_t	mode,
		dev_t	dev
	)

Create an IMFS node.

Routine to create a node in the IMFS file system.

IMFS_readlink()

ssize_t IMFS_readlink	(	const rtems_filesystem_location_info_t *	loc,
		char *	buf,
		size_t	bufsize
	)

Put IMFS symbolic link into buffer.

The following rouine puts the symbolic links destination name into buff.

IMFS_rename()

int IMFS_rename	(	const rtems_filesystem_location_info_t *	oldparentloc,
		const rtems_filesystem_location_info_t *	oldloc,
		const rtems_filesystem_location_info_t *	newparentloc,
		const char *	name,
		size_t	namelen
	)

Rename the IMFS.

The following rouine creates a new link node under parent with the name given in name and removes the old.

IMFS_rmnod()

int IMFS_rmnod	(	const rtems_filesystem_location_info_t *	parentloc,
		const rtems_filesystem_location_info_t *	loc
	)

IMFS node removal handler.

This file contains the handler used to remove a node when a file type does not require special actions.

IMFS_stat()

int IMFS_stat	(	const rtems_filesystem_location_info_t *	loc,
		struct stat *	buf
	)

Perform a status processing for the IMFS.

This routine provides a stat for the IMFS file system.

IMFS_symlink()

int IMFS_symlink	(	const rtems_filesystem_location_info_t *	parentloc,
		const char *	name,
		size_t	namelen,
		const char *	target
	)

Create a new IMFS symbolic link node.

The following rouine creates a new symbolic link node under parent with the name given in name. The node is set to point to the node at to_loc.

IMFS_utime()

int IMFS_utime	(	const rtems_filesystem_location_info_t *	loc,
		time_t	actime,
		time_t	modtime
	)

Set IMFS file access and modification times.

This routine is the implementation of the utime() system call for the IMFS.

rtems_tarfs_load()

int rtems_tarfs_load	(	const char *	mountpoint,
		uint8_t *	tar_image,
		size_t	tar_size
	)

RTEMS load tarfs.

This file implements the "mount" procedure for tar-based IMFS extensions. The TAR is not actually mounted under the IMFS. Directories from the TAR file are created as usual in the IMFS. File entries are created as IMFS_LINEAR_FILE nodes with their nods pointing to addresses in the TAR image.

Here we create the mountpoint directory and load the tarfs at that node. Once the IMFS has been mounted, we work through the tar image and perform as follows:

• For directories, simply call mkdir(). The IMFS creates nodes as needed.
• For files, we make our own calls to IMFS eval_for_make and create_node.

TAR file format:

Offset   Length                 Contents
  0    100  bytes  File name ('\0' terminated, 99 maxmum length)
100      8  bytes  File mode (in octal ascii)
108      8  bytes  User ID (in octal ascii)
116      8  bytes  Group ID (in octal ascii)
124     12  bytes  File size (s) (in octal ascii)
136     12  bytes  Modify time (in octal ascii)
148      8  bytes  Header checksum (in octal ascii)
156      1  bytes  Link flag
157    100  bytes  Linkname ('\0' terminated, 99 maxmum length)
257      8  bytes  Magic PAX ("ustar\0" + 2 bytes padding)
257      8  bytes  Magic GNU tar ("ustar  \0")
265     32  bytes  User name ('\0' terminated, 31 maxmum length)
297     32  bytes  Group name ('\0' terminated, 31 maxmum length)
329      8  bytes  Major device ID (in octal ascii)
337      8  bytes  Minor device ID (in octal ascii)
345    167  bytes  Padding
512   (s+p) bytes  File contents (s+p) := (((s) + 511) & ~511),
                   round up to 512 bytes

Checksum:

int   i, sum;
char *header = tar_header_pointer;

sum = 0;
for (i = 0; i < 512; i++)
    sum += 0xFF & header[i];