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authorChris Johns <chrisj@rtems.org>2016-10-29 05:09:35 +1100
committerChris Johns <chrisj@rtems.org>2016-10-29 05:09:35 +1100
commit23a5ce44981ae3c5d92885ac089b2be825d2550e (patch)
tree6510c434a004fb3dabfab5c290bd2f520dd5f45c /filesystem
parent2592441410608c414b5a4fa601f291010b985b04 (diff)
downloadrtems-docs-23a5ce44981ae3c5d92885ac089b2be825d2550e.tar.bz2
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-.. comment SPDX-License-Identifier: CC-BY-SA-4.0
-
-:orphan:
-
-
-
-.. COMMENT: %**end of header
-
-.. COMMENT: COPYRIGHT (c) 1989-2013.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-.. COMMENT: Master file for the Filesystem Design Guide
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-.. COMMENT: The following determines which set of the tables and figures we will use.
-
-.. COMMENT: We default to ASCII but if available TeX or HTML versions will
-
-.. COMMENT: be used instead.
-
-.. COMMENT: @clear use-html
-
-.. COMMENT: @clear use-tex
-
-.. COMMENT: The following variable says to use texinfo or html for the two column
-
-.. COMMENT: texinfo tables. For somethings the format does not look good in html.
-
-.. COMMENT: With our adjustment to the left column in TeX, it nearly always looks
-
-.. COMMENT: good printed.
-
-.. COMMENT: Custom whitespace adjustments. We could fiddle a bit more.
-
-.. COMMENT: Title Page Stuff
-
-.. COMMENT: I don't really like having a short title page. -joel
-
-.. COMMENT: @shorttitlepage RTEMS Filesystem Design Guide
-
-=============================
-RTEMS Filesystem Design Guide
-=============================
-
-.. COMMENT: COPYRIGHT (c) 1988-2015.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-.. COMMENT: The following puts a space somewhere on an otherwise empty page so we
-
-.. COMMENT: can force the copyright description onto a left hand page.
-
-COPYRIGHT © 1988 - 2015.
-
-On-Line Applications Research Corporation (OAR).
-
-The authors have used their best efforts in preparing
-this material. These efforts include the development, research,
-and testing of the theories and programs to determine their
-effectiveness. No warranty of any kind, expressed or implied,
-with regard to the software or the material contained in this
-document is provided. No liability arising out of the
-application or use of any product described in this document is
-assumed. The authors reserve the right to revise this material
-and to make changes from time to time in the content hereof
-without obligation to notify anyone of such revision or changes.
-
-The RTEMS Project is hosted at http://www.rtems.org. Any
-inquiries concerning RTEMS, its related support components, or its
-documentation should be directed to the Community Project hosted athttp://www.rtems.org.
-
-Any inquiries for commercial services including training, support, custom
-development, application development assistance should be directed tohttp://www.rtems.com.
-
-.. COMMENT: This prevents a black box from being printed on "overflow" lines.
-
-.. COMMENT: The alternative is to rework a sentence to avoid this problem.
-
-RTEMS Filesystem Design Guide
-#############################
-
-.. COMMENT: COPYRIGHT (c) 1989-2011.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-Preface
-#######
-
-This document describes the implementation of the RTEMS filesystem
-infrastructure. This infrastructure supports the following
-capabilities:
-
-- Mountable file systems
-
-- Hierarchical file system directory structure
-
-- POSIX compliant set of routines for the manipulation of files and directories
-
-- Individual file and directory support for the following:
- # Permissions for read, write and execute
- # User ID
- # Group ID
- # Access time
- # Modification time
- # Creation time
-
-- Hard links to files and directories
-
-- Symbolic links to files and directories
-
-This has been implemented to provide the framework for a UNIX-like
-file system support. POSIX file and directory functions have been
-implemented that allow a standard method of accessing file, device and
-directory information within file systems. The file system concept that
-has been implemented allows for expansion and adaptation of the file
-system to a variety of existing and future data storage devices. To this
-end, file system mount and unmount capabilities have been included in this
-RTEMS framework.
-
-This framework slightly alters the manner in which devices are handled
-under RTEMS from that of public release 4.0.0 and earlier. Devices that
-are defined under a given RTEMS configuration will now be registered as
-files in a mounted file system. Access to these device drivers and their
-associated devices may now be performed through the traditional file system
-open(), read(), write(), lseek(), fstat() and ioctl() functions in addition
-to the interface provided by the IO Manager in the RTEMS Classic API.
-
-An In-Memory File System (IMFS) is included which provides full POSIX
-filesystem functionality yet is RAM based. The IMFS maintains a
-node structure for each file, device, and directory in each mounted
-instantiation of its file system. The node structure is used to
-manage ownership, access rights, access time, modification time,
-and creation time. A union of structures within the IMFS nodal
-structure provide for manipulation of file data, device selection,
-or directory content as required by the nodal type. Manipulation of
-these properties is accomplished through the POSIX set of file and
-directory functions. In addition to being useful in its own right,
-the IMFS serves as a full featured example filesystem.
-
-The intended audience for this document is those persons implementing
-their own filesystem. Users of the filesystem may find information
-on the implementation useful. But the user interface to the filesystem
-is through the ISO/ANSI C Library and POSIX 1003.1b file and directory
-APIs.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-Pathname Evaluation
-###################
-
-This chapter describes the pathname evaluation process for the
-RTEMS Filesystem Infrastructure.
-.. code:: c
-
- XXX Include graphic of the path evaluation process
-
-Pathname Evaluation Handlers
-============================
-
-There are two pathname evaluation routines. The handler patheval()
-is called to find, verify privlages on and return information on a node
-that exists. The handler evalformake() is called to find, verify
-permissions, and return information on a node that is to become a parent.
-Additionally, evalformake() returns a pointer to the start of the name of
-the new node to be created.
-
-Pathname evaluation is specific to a filesystem.
-Each filesystem is required to provide both a patheval() and an evalformake()
-routine. Both of these routines gets a name to evaluate and a node indicating
-where to start the evaluation.
-
-Crossing a Mount Point During Path Evaluation
-=============================================
-
-If the filesystem supports the mount command, the evaluate routines
-must handle crossing the mountpoint. The evaluate routine should evaluate
-the name upto the first directory node where the new filesystem is mounted.
-The filesystem may process terminator characters prior to calling the
-evaluate routine for the new filesystem. A pointer to the portion of the
-name which has not been evaluated along with the root node of the new
-file system ( gotten from the mount table entry ) is passed to the correct
-mounted filesystem evaluate routine.
-
-The rtems_filesystem_location_info_t Structure
-==============================================
-
-The ``rtems_filesystem_location_info_t`` structure contains all information
-necessary for identification of a node.
-
-The generic rtems filesystem code defines two global
-rtems_filesystem_location_info_t structures, the``rtems_filesystem_root`` and the ``rtems_filesystem_current``.
-Both are initially defined to be the root node of the base filesystem.
-Once the chdir command is correctly used the ``rtems_filesystem_current``
-is set to the location specified by the command.
-
-The filesystem generic code peeks at the first character in the name to be
-evaluated. If this character is a valid seperator, the``rtems_filesystem_root`` is used as the node to start the evaluation
-with. Otherwise, the ``rtems_filesystem_current`` node is used as the
-node to start evaluating with. Therefore, a valid
-rtems_filesystem_location_info_t is given to the evaluate routine to start
-evaluation with. The evaluate routines are then responsible for making
-any changes necessary to this structure to correspond to the name being
-parsed.
-.. code:: c
-
- struct rtems_filesystem_location_info_tt {
- void \*node_access;
- rtems_filesystem_file_handlers_r \*handlers;
- rtems_filesystem_operations_table \*ops;
- rtems_filesystem_mount_table_entry_t \*mt_entry;
- };
-
-*node_access*
- This element is filesystem specific. A filesystem can define and store
- any information necessary to identify a node at this location. This element
- is normally filled in by the filesystem’s evaluate routine. For the
- filesystem’s root node, the filesystem’s initilization routine should
- fill this in, and it should remain valid until the instance of the
- filesystem is unmounted.
-
-*handlers*
- This element is defined as a set of routines that may change within a
- given filesystem based upon node type. For example a directory and a
- memory file may have to completely different read routines. This element
- is set to an initialization state defined by the mount table, and may
- be set to the desired state by the evaluation routines.
-
-*ops*
- This element is defined as a set of routines that remain static for the
- filesystem. This element identifies entry points into the filesystem
- to the generic code.
-
-*mt_entry*
- This element identifies the mount table entry for this instance of the
- filesystem.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-System Initialization
-#####################
-
-After the RTEMS initialization is performed, the application’s
-initialization will be performed. Part of initialization is a call to
-rtems_filesystem_initialize(). This routine will mount the ‘In Memory File
-System’ as the base filesystem. Mounting the base filesystem consists
-of the following:
-
-- Initialization of mount table chain control structure
-
-- Allocation of a ``jnode`` structure that will server as the root node
- of the ‘In Memory Filesystem’
-
-- Initialization of the allocated ``jnode`` with the appropriate OPS,
- directory handlers and pathconf limits and options.
-
-- Allocation of a memory region for filesystem specific global
- management variables
-
-- Creation of first mount table entry for the base filesystem
-
-- Initialization of the first mount table chain entry to indicate that
- the mount point is NULL and the mounted filesystem is the base file
- system
-
-After the base filesystem has been mounted, the following operations are
-performed under its directory structure:
-
-- Creation of the /dev directory
-
-- Registration of devices under /dev directory
-
-Base Filesystem
-===============
-
-RTEMS initially mounts a RAM based file system known as the base file system.
-The root directory of this file system tree serves as the logical root of the
-directory hierarchy (Figure 3). Under the root directory a ‘/dev’ directory
-is created under which all I/O device directories and files are registered as
-part of the file system hierarchy.
-.. code:: c
-
- Figure of the tree structure goes here.
-
-A RAM based file system draws its management resources from memory. File and
-directory nodes are simply allocated blocks of memory. Data associated with
-regular files is stored in collections of memory blocks. When the system is
-turned off or restarted all memory-based components of the file system are
-lost.
-
-The base file system serves as a starting point for the mounting of file
-systems that are resident on semi-permanent storage media. Examples of such
-media include non- volatile memory, flash memory and IDE hard disk drives
-(Figure 3). File systems of other types will be mounted onto mount points
-within the base file system or other file systems that are subordinate to the
-base file system. The framework set up under the base file system will allow
-for these new file system types and the unique data and functionality that is
-required to manage the future file systems.
-
-Base Filesystem Mounting
-------------------------
-
-At present, the first file system to be mounted is the ‘In Memory File
-System’. It is mounted using a standard MOUNT() command in which the mount
-point is NULL. This flags the mount as the first file system to be
-registered under the operating system and appropriate initialization of file
-system management information is performed (See figures 4 and 5). If a
-different file system type is desired as the base file system, alterations
-must be made to base_fs.c. This routine handles the mount of the base file
-system.
-
-.. code:: c
-
- Figure of the mount table chain goes here.
-
-Once the root of the base file system has been established and it has been
-recorded as the mount point of the base file system, devices are integrated
-into the base file system. For every device that is configured into the
-system (See ioman.c) a device registration process is performed. Device
-registration produces a unique dev_t handle that consists of a major and
-minor device number. In addition, the configuration information for each
-device contains a text string that represents the fully qualified pathname to
-that device’s place in the base file system’s hierarchy. A file system node
-is created for the device along the specified registration path.
-
-.. code:: c
-
- Figure of the Mount Table Processing goes here.
-
-Note: Other file systems can be mounted but they are mounted onto points
-(directory mount points) in the base file system.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-Mounting and Unmounting Filesystems
-###################################
-
-Mount Points
-============
-
-The following is the list of the characteristics of a mount point:
-
-- The mount point must be a directory. It may have files and other
- directories under it. These files and directories will be hidden when the
- filesystem is mounted.
-
-- The task must have read/write/execute permissions to the mount point
- or the mount attempt will be rejected.
-
-- Only one filesystem can be mounted to a single mount point.
-
-- The Root of the mountable filesystem will be referenced by the name
- of the mount point after the mount is complete.
-
-Mount Table Chain
-=================
-
-The mount table chain is a dynamic list of structures that describe
-mounted filesystems a specific points in the filesystem hierarchy. It is
-initialized to an empty state during the base filesystem initialization.
-The mount operation will add entries to the mount table chain. The
-un-mount operation will remove entries from the mount table chain.
-
-Each entry in the mount table chain is of the following type:
-.. code:: c
-
- struct rtems_filesystem_mount_table_entry_tt
- {
- Chain_Node Node;
- rtems_filesystem_location_info_t mt_point_node;
- rtems_filesystem_location_info_t mt_fs_root;
- int options;
- void \*fs_info;
- rtems_filesystem_limits_and_options_t pathconf_limits_and_options;
- /*
- * When someone adds a mounted filesystem on a real device,
- * this will need to be used.
- *
- * The best option long term for this is probably an
- * open file descriptor.
- \*/
- char \*dev;
- };
-
-*Node*
- The Node is used to produce a linked list of mount table entry nodes.
-
-*mt_point_node*
- The mt_point_node contains all information necessary to access the
- directory where a filesystem is mounted onto. This element may contain
- memory that is allocated during a path evaluation of the filesystem
- containing the mountpoint directory. The generic code allows this
- memory to be returned by unmount when the filesystem identified by
- mt_fs_root is unmounted.
-
-*mt_fs_root*
- The mt_fs_root contains all information necessary to identify the root
- of the mounted filesystem. The user is never allowed access to this
- node by the generic code, but it is used to identify to the mounted
- filesystem where to start evaluation of pathnames at.
-
-*options*
- XXX
-
-*fs_info*
- The fs_info element is a location available for use by the mounted file
- system to identify unique things applicable to this instance of the file
- system. For example the IMFS uses this space to provide node
- identification that is unique for each instance (mounting) of the filesystem.
-
-*pathconf_limits_and_options*
- XXX
-
-*dev*
- This character string represents the device where the filesystem will reside.
-
-Adding entries to the chain during mount
-========================================
-
-When a filesystem is mounted, its presence and location in the file
-system hierarchy is recorded in a dynamic list structure known as a chain.
-A unique rtems_filesystem_mount_table_entry_tt structure is logged for
-each filesystem that is mounted. This includes the base filesystem.
-
-Removing entries from the chain during unmount
-==============================================
-
-When a filesystem is dismounted its entry in the mount table chain is
-extracted and the memory for this entry is freed.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-System Call Development Notes
-#############################
-
-This set of routines represents the application’s interface to files and directories
-under the RTEMS filesystem. All routines are compliant with POSIX standards if a
-specific interface has been established. The list below represents the routines that have
-been included as part of the application’s interface.
-
-# access()
-
-# chdir()
-
-# chmod()
-
-# chown()
-
-# close()
-
-# closedir()
-
-# dup()
-
-# dup2()
-
-# fchmod()
-
-# fcntl()
-
-# fdatasync()
-
-# fpathconf()
-
-# fstat()
-
-# ioctl()
-
-# link()
-
-# lseek()
-
-# mkdir()
-
-# mkfifo()
-
-# mknod()
-
-# mount()
-
-# open()
-
-# opendir()
-
-# pathconf()
-
-# read()
-
-# readdir()
-
-# unmount()
-
-The sections that follow provide developmental information concerning each
-of these functions.
-
-.. COMMENT: @page
-
-access
-======
-
-**File:**
-
-access.c
-
-**Processing:**
-
-This routine is layered on the stat() function. It acquires the current
-status information for the specified file and then determines if the
-caller has the ability to access the file for read, write or execute
-according to the mode argument to this function.
-
-**Development Comments:**
-
-This routine is layered on top of the stat() function. As long as the
-st_mode element in the returned structure follow the standard UNIX
-conventions, this function should support other filesystems without
-alteration.
-
-.. COMMENT: @page
-
-chdir
-=====
-
-**File:**
-
-chdir.c
-
-**Processing:**
-
-This routine will determine if the pathname that we are attempting to make
-that current directory exists and is in fact a directory. If these
-conditions are met the global indication of the current directory
-(rtems_filesystem_current) is set to the rtems_filesystem_location_info_t
-structure that is returned by the rtems_filesystem_evaluate_path()
-routine.
-
-**Development Comments:**
-
-This routine is layered on the rtems_filesystem_evaluate_path() routine
-and the filesystem specific OP table function node_type().
-
-The routine node_type() must be a routine provided for each filesystem
-since it must access the filesystems node information to determine which
-of the following types the node is:
-
-- RTEMS_FILESYSTEM_DIRECTORY
-
-- RTEMS_FILESYSTEM_DEVICE
-
-- RTEMS_FILESYSTEM_HARD_LINK
-
-- RTEMS_FILESYSTEM_MEMORY_FILE
-
-This acknowledges that the form of the node management information can
-vary from one filesystem implementation to another.
-
-RTEMS has a special global structure that maintains the current directory
-location. This global variable is of type rtems_filesystem_location_info_t
-and is called rtems_filesystem_current. This structure is not always
-valid. In order to determine if the structure is valid, you must first
-test the node_access element of this structure. If the pointer is NULL,
-then the structure does not contain a valid indication of what the current
-directory is.
-
-.. COMMENT: @page
-
-chmod
-=====
-
-**File:**
-
-chmod.c
-
-**Processing:**
-
-This routine is layered on the open(), fchmod() and close() functions. As
-long as the standard interpretation of the mode_t value is maintained,
-this routine should not need modification to support other filesystems.
-
-**Development Comments:**
-
-The routine first determines if the selected file can be open with
-read/write access. This is required to allow modification of the mode
-associated with the selected path.
-
-The fchmod() function is used to actually change the mode of the path
-using the integer file descriptor returned by the open() function.
-
-After mode modification, the open file descriptor is closed.
-
-.. COMMENT: @page
-
-chown
-=====
-
-**File:**
-
-chown.c
-
-**Processing:**
-
-This routine is layered on the rtems_filesystem_evaluate_path() and the
-file system specific chown() routine that is specified in the OPS table
-for the file system.
-
-**Development Comments:**
-
-rtems_filesystem_evaluate_path() is used to determine if the path
-specified actually exists. If it does a rtems_filesystem_location_info_t
-structure will be obtained that allows the shell function to locate the
-OPS table that is to be used for this filesystem.
-
-It is possible that the chown() function that should be in the OPS table
-is not defined. A test for a non-NULL OPS table chown() entry is performed
-before the function is called.
-
-If the chown() function is defined in the indicated OPS table, the
-function is called with the rtems_filesystem_location_info_t structure
-returned from the path evaluation routine, the desired owner, and group
-information.
-
-.. COMMENT: @page
-
-close
-=====
-
-**File:**
-
-close.c
-
-**Processing:**
-
-This routine will allow for the closing of both network connections and
-file system devices. If the file descriptor is associated with a network
-device, the appropriate network function handler will be selected from a
-table of previously registered network functions (rtems_libio_handlers)
-and that function will be invoked.
-
-If the file descriptor refers to an entry in the filesystem, the
-appropriate handler will be selected using information that has been
-placed in the file control block for the device (rtems_libio_t structure).
-
-**Development Comments:**
-
-rtems_file_descriptor_type examines some of the upper bits of the file
-descriptor index. If it finds that the upper bits are set in the file
-descriptor index, the device referenced is a network device.
-
-Network device handlers are obtained from a special registration table
-(rtems_libio_handlers) that is set up during network initialization. The
-network handler invoked and the status of the network handler will be
-returned to the calling process.
-
-If none of the upper bits are set in the file descriptor index, the file
-descriptor refers to an element of the RTEMS filesystem.
-
-The following sequence will be performed for any filesystem file
-descriptor:
-
-# Use the rtems_libio_iop() function to obtain the rtems_libio_t
- structure for the file descriptor
-
-# Range check the file descriptor using rtems_libio_check_fd()
-
-# Determine if there is actually a function in the selected handler
- table that processes the close() operation for the filesystem and node
- type selected. This is generally done to avoid execution attempts on
- functions that have not been implemented.
-
-# If the function has been defined it is invoked with the file control
- block pointer as its argument.
-
-# The file control block that was associated with the open file
- descriptor is marked as free using rtems_libio_free().
-
-# The return code from the close handler is then passed back to the
- calling program.
-
-.. COMMENT: @page
-
-closedir
-========
-
-**File:**
-
-closedir.c
-
-**Processing:**
-
-The code was obtained from the BSD group. This routine must clean up the
-memory resources that are required to track an open directory. The code is
-layered on the close() function and standard memory free() functions. It
-should not require alterations to support other filesystems.
-
-**Development Comments:**
-
-The routine alters the file descriptor and the index into the DIR
-structure to make it an invalid file descriptor. Apparently the memory
-that is about to be freed may still be referenced before it is
-reallocated.
-
-The dd_buf structure’s memory is reallocated before the control structure
-that contains the pointer to the dd_buf region.
-
-DIR control memory is reallocated.
-
-The close() function is used to free the file descriptor index.
-
-.. COMMENT: @page
-
-dup() Unimplemented
-========================
-
-**File:**
-
-dup.c
-
-**Processing:**
-
-**Development Comments:**
-
-.. COMMENT: @page
-
-dup2() Unimplemented
-=========================
-
-**File:**
-
-dup2.c
-
-**Processing:**
-
-**Development Comments:**
-
-.. COMMENT: @page
-
-fchmod
-======
-
-**File:**
-
-fchmod.c
-
-**Processing:**
-
-This routine will alter the permissions of a node in a filesystem. It is
-layered on the following functions and macros:
-
-- rtems_file_descriptor_type()
-
-- rtems_libio_iop()
-
-- rtems_libio_check_fd()
-
-- rtems_libio_check_permissions()
-
-- fchmod() function that is referenced by the handler table in the
- file control block associated with this file descriptor
-
-**Development Comments:**
-
-The routine will test to see if the file descriptor index is associated
-with a network connection. If it is, an error is returned from this
-routine.
-
-The file descriptor index is used to obtain the associated file control
-block.
-
-The file descriptor value is range checked.
-
-The file control block is examined to determine if it has write
-permissions to allow us to alter the mode of the file.
-
-A test is made to determine if the handler table that is referenced in the
-file control block contains an entry for the fchmod() handler function. If
-it does not, an error is returned to the calling routine.
-
-If the fchmod() handler function exists, it is called with the file
-control block and the desired mode as parameters.
-
-.. COMMENT: @page
-
-fcntl()
-=======
-
-**File:**
-
-fcntl.c
-
-**Processing:**
-
-This routine currently only interacts with the file control block. If the
-structure of the file control block and the associated meanings do not
-change, the partial implementation of fcntl() should remain unaltered for
-other filesystem implementations.
-
-**Development Comments:**
-
-The only commands that have been implemented are the F_GETFD and F_SETFD.
-The commands manipulate the LIBIO_FLAGS_CLOSE_ON_EXEC bit in the``flags`` element of the file control block associated with the file
-descriptor index.
-
-The current implementation of the function performs the sequence of
-operations below:
-
-# Test to see if we are trying to operate on a file descriptor
- associated with a network connection
-
-# Obtain the file control block that is associated with the file
- descriptor index
-
-# Perform a range check on the file descriptor index.
-
-.. COMMENT: @page
-
-fdatasync
-=========
-
-**File:**
-
-fdatasync.c
-
-**Processing:**
-
-This routine is a template in the in memory filesystem that will route us to the
-appropriate handler function to carry out the fdatasync() processing. In the in
-memory filesystem this function is not necessary. Its function in a disk based file
-system that employs a memory cache is to flush all memory based data buffers to
-disk. It is layered on the following functions and macros:
-
-- rtems_file_descriptor_type()
-
-- rtems_libio_iop()
-
-- rtems_libio_check_fd()
-
-- rtems_libio_check_permissions()
-
-- fdatasync() function that is referenced by the handler table in the
- file control block associated with this file descriptor
-
-**Development Comments:**
-
-The routine will test to see if the file descriptor index is associated
-with a network connection. If it is, an error is returned from this
-routine.
-
-The file descriptor index is used to obtain the associated file control
-block.
-
-The file descriptor value is range checked.
-
-The file control block is examined to determine if it has write
-permissions to the file.
-
-A test is made to determine if the handler table that is referenced in the
-file control block contains an entry for the fdatasync() handler function.
-If it does not an error is returned to the calling routine.
-
-If the fdatasync() handler function exists, it is called with the file
-control block as its parameter.
-
-.. COMMENT: @page
-
-fpathconf
-=========
-
-**File:**
-
-fpathconf.c
-
-**Processing:**
-
-This routine is layered on the following functions and macros:
-
-- rtems_file_descriptor_type()
-
-- rtems_libio_iop()
-
-- rtems_libio_check_fd()
-
-- rtems_libio_check_permissions()
-
-When a filesystem is mounted, a set of constants is specified for the
-filesystem. These constants are stored with the mount table entry for the
-filesystem. These constants appear in the POSIX standard and are listed
-below.
-
-- PCLINKMAX
-
-- PCMAXCANON
-
-- PCMAXINPUT
-
-- PCNAMEMAX
-
-- PCPATHMAX
-
-- PCPIPEBUF
-
-- PCCHOWNRESTRICTED
-
-- PCNOTRUNC
-
-- PCVDISABLE
-
-- PCASYNCIO
-
-- PCPRIOIO
-
-- PCSYNCIO
-
-This routine will find the mount table information associated the file
-control block for the specified file descriptor parameter. The mount table
-entry structure contains a set of filesystem specific constants that can
-be accessed by individual identifiers.
-
-**Development Comments:**
-
-The routine will test to see if the file descriptor index is associated
-with a network connection. If it is, an error is returned from this
-routine.
-
-The file descriptor index is used to obtain the associated file control
-block.
-
-The file descriptor value is range checked.
-
-The file control block is examined to determine if it has read permissions
-to the file.
-
-Pathinfo in the file control block is used to locate the mount table entry
-for the filesystem associated with the file descriptor.
-
-The mount table entry contains the pathconf_limits_and_options element.
-This element is a table of constants that is associated with the
-filesystem.
-
-The name argument is used to reference the desired constant from the
-pathconf_limits_and_options table.
-
-.. COMMENT: @page
-
-fstat
-=====
-
-**File:**
-
-fstat.c
-
-**Processing:**
-
-This routine will return information concerning a file or network
-connection. If the file descriptor is associated with a network
-connection, the current implementation of ``fstat()`` will return a
-mode set to ``S_IFSOCK``. In a later version, this routine will map the
-status of a network connection to an external handler routine.
-
-If the file descriptor is associated with a node under a filesystem, the
-fstat() routine will map to the fstat() function taken from the node
-handler table.
-
-**Development Comments:**
-
-This routine validates that the struct stat pointer is not NULL so that
-the return location is valid.
-
-The struct stat is then initialized to all zeros.
-
-rtems_file_descriptor_type() is then used to determine if the file
-descriptor is associated with a network connection. If it is, network
-status processing is performed. In the current implementation, the file
-descriptor type processing needs to be improved. It currently just drops
-into the normal processing for file system nodes.
-
-If the file descriptor is associated with a node under a filesystem, the
-following steps are performed:
-
-# Obtain the file control block that is associated with the file descriptor
- index.
-
-# Range check the file descriptor index.
-
-# Test to see if there is a non-NULL function pointer in the handler
- table for the fstat() function. If there is, invoke the function with the
- file control block and the pointer to the stat structure.
-
-.. COMMENT: @page
-
-ioctl
-=====
-
-**File:**
-
-ioctl.c
-
-**Processing:**
-
-Not defined in the POSIX 1003.1b standard but commonly supported in most
-UNIX and POSIX system. Ioctl() is a catchall for I/O operations. Routine
-is layered on external network handlers and filesystem specific handlers.
-The development of new filesystems should not alter the basic processing
-performed by this routine.
-
-**Development Comments:**
-
-The file descriptor is examined to determine if it is associated with a
-network device. If it is processing is mapped to an external network
-handler. The value returned by this handler is then returned to the
-calling program.
-
-File descriptors that are associated with a filesystem undergo the
-following processing:
-
-# The file descriptor index is used to obtain the associated file
- control block.
-
-# The file descriptor value is range checked.
-
-# A test is made to determine if the handler table that is referenced
- in the file control block contains an entry for the ioctl() handler
- function. If it does not, an error is returned to the calling routine.
-
-# If the ioctl() handler function exists, it is called with the file
- control block, the command and buffer as its parameters.
-
-# The return code from this function is then sent to the calling
- routine.
-
-.. COMMENT: @page
-
-link
-====
-
-**File:**
-
-link.c
-
-**Processing:**
-
-This routine will establish a hard link to a file, directory or a device.
-The target of the hard link must be in the same filesystem as the new link
-being created. A link to an existing link is also permitted but the
-existing link is evaluated before the new link is made. This implies that
-links to links are reduced to links to files, directories or devices
-before they are made.
-
-**Development Comments:**
-
-Calling parameters:
-const char \*existing
-const char \*new
-
-link() will determine if the target of the link actually exists using
-rtems_filesystem_evaluate_path()
-
-rtems_filesystem_get_start_loc() is used to determine where to start the
-path evaluation of the new name. This macro examines the first characters
-of the name to see if the name of the new link starts with a
-rtems_filesystem_is_separator. If it does the search starts from the root
-of the RTEMS filesystem; otherwise the search will start from the current
-directory.
-
-The OPS table evalformake() function for the parent’s filesystem is used
-to locate the node that will be the parent of the new link. It will also
-locate the start of the new path’s name. This name will be used to define
-a child under the parent directory.
-
-If the parent is found, the routine will determine if the hard link that
-we are trying to create will cross a filesystem boundary. This is not
-permitted for hard-links.
-
-If the hard-link does not cross a filesystem boundary, a check is
-performed to determine if the OPS table contains an entry for the link()
-function.
-
-If a link() function is defined, the OPS table link() function will be
-called to establish the actual link within the filesystem.
-
-The return code from the OPS table link() function is returned to the
-calling program.
-
-.. COMMENT: @page
-
-lseek
-=====
-
-**File:**
-
-lseek.c
-
-**Processing:**
-
-This routine is layered on both external handlers and filesystem / node
-type specific handlers. This routine should allow for the support of new
-filesystems without modification.
-
-**Development Comments:**
-
-This routine will determine if the file descriptor is associated with a
-network device. If it is lseek will map to an external network handler.
-The handler will be called with the file descriptor, offset and whence as
-its calling parameters. The return code from the external handler will be
-returned to the calling routine.
-
-If the file descriptor is not associated with a network connection, it is
-associated with a node in a filesystem. The following steps will be
-performed for filesystem nodes:
-
-# The file descriptor is used to obtain the file control block for the
- node.
-
-# The file descriptor is range checked.
-
-# The offset element of the file control block is altered as indicated
- by the offset and whence calling parameters
-
-# The handler table in the file control block is examined to determine
- if it contains an entry for the lseek() function. If it does not an error
- is returned to the calling program.
-
-# The lseek() function from the designated handler table is called
- with the file control block, offset and whence as calling arguments
-
-# The return code from the lseek() handler function is returned to the
- calling program
-
-.. COMMENT: @page
-
-mkdir
-=====
-
-**File:**
-
-mkdir.c
-
-**Processing:**
-
-This routine attempts to create a directory node under the filesystem. The
-routine is layered the mknod() function.
-
-**Development Comments:**
-
-See mknod() for developmental comments.
-
-.. COMMENT: @page
-
-mkfifo
-======
-
-**File:**
-
-mkfifo.c
-
-**Processing:**
-
-This routine attempts to create a FIFO node under the filesystem. The
-routine is layered the mknod() function.
-
-**Development Comments:**
-
-See mknod() for developmental comments
-
-.. COMMENT: @page
-
-mknod
-=====
-
-**File:**
-
-mknod.c
-
-**Processing:**
-
-This function will allow for the creation of the following types of nodes
-under the filesystem:
-
-- directories
-
-- regular files
-
-- character devices
-
-- block devices
-
-- fifos
-
-At the present time, an attempt to create a FIFO will result in an ENOTSUP
-error to the calling function. This routine is layered the filesystem
-specific routines evalformake and mknod. The introduction of a new
-filesystem must include its own evalformake and mknod function to support
-the generic mknod() function. Under this condition the generic mknod()
-function should accommodate other filesystem types without alteration.
-
-**Development Comments:**
-
-Test for nodal types - I thought that this test should look like the
-following code:
-.. code:: c
-
- if ( (mode & S_IFDIR) = = S_IFDIR) \||
- (mode & S_IFREG) = = S_IFREG) \||
- (mode & S_IFCHR) = = S_IFCHR) \||
- (mode & S_IFBLK) = = S_IFBLK) \||
- (mode & S_IFIFO) = = S_IFIFO))
- Set_errno_and_return_minus_one (EINVAL);
-
-Where:
-
-- S_IFREG (0100000) - Creation of a regular file
-
-- S_IFCHR (0020000) - Creation of a character device
-
-- S_IFBLK (0060000) - Creation of a block device
-
-- S_IFIFO (0010000) - Creation of a FIFO
-
-Determine if the pathname that we are trying to create starts at the root
-directory or is relative to the current directory using the
-rtems_filesystem_get_start_loc() function.
-
-Determine if the pathname leads to a valid directory that can be accessed
-for the creation of a node.
-
-If the pathname is a valid location to create a node, verify that a
-filesystem specific mknod() function exists.
-
-If the mknod() function exists, call the filesystem specific mknod()
-function. Pass the name, mode, device type and the location information
-associated with the directory under which the node will be created.
-
-.. COMMENT: @page
-
-mount
-=====
-
-**File:**
-
-mount.c
-
-Arguments (Not a standard POSIX call):
-
-rtems_filesystem_mount_table_entry_t \**mt_entry,
-
-If the mount operation is successful, this pointer to a pointer will be
-set to reference the mount table chain entry that has been allocated for
-this file system mount.
-
-rtems_filesystem_operations_table \*fs_ops,
-
-This is a pointer to a table of functions that are associated with the
-file system that we are about to mount. This is the mechanism to selected
-file system type without keeping a dynamic database of all possible file
-system types that are valid for the mount operation. Using this method, it
-is only necessary to configure the filesystems that we wish to use into
-the RTEMS build. Unused filesystems types will not be drawn into the
-build.
-
-char \*fsoptions,
-
-This argument points to a string that selects mounting for read only
-access or read/write access. Valid states are "RO" and "RW"
-
-char \*device,
-
-This argument is reserved for the name of a device that will be used to
-access the filesystem information. Current filesystem implementations are
-memory based and do not require a device to access filesystem information.
-
-char \*mount_point
-
-This is a pathname to a directory in a currently mounted filesystem that
-allows read, write and execute permissions. If successful, the node found
-by evaluating this name, is stored in the mt_entry.
-
-**Processing:**
-
-This routine will handle the mounting of a filesystem on a mount point. If
-the operation is successful, a pointer to the mount table chain entry
-associated with the mounted filesystem will be returned to the calling
-function. The specifics about the processing required at the mount point
-and within the filesystem being mounted is isolated in the filesystem
-specific mount() and fsmount_me() functions. This allows the generic
-mount() function to remain unaltered even if new filesystem types are
-introduced.
-
-**Development Comments:**
-
-This routine will use get_file_system_options() to determine if the mount
-options are valid ("RO" or "RW").
-
-It confirms that a filesystem ops-table has been selected.
-
-Space is allocated for a mount table entry and selective elements of the
-temporary mount table entry are initialized.
-
-If a mount point is specified: The mount point is examined to determine
-that it is a directory and also has the appropriate permissions to allow a
-filesystem to be mounted.
-
-The current mount table chain is searched to determine that there is not
-another filesystem mounted at the mount point we are trying to mount onto.
-
-If a mount function is defined in the ops table for the filesystem
-containing the mount point, it is called at this time.
-
-If no mount point is specified: Processing if performed to set up the
-mount table chain entry as the base filesystem.
-
-If the fsmount_me() function is specified for ops-table of the filesystem
-being mounted, that function is called to initialize for the new
-filesystem.
-
-On successful completion, the temporary mount table entry will be placed
-on the mount table chain to record the presence of the mounted filesystem.
-
-.. COMMENT: @page
-
-open
-====
-
-**File:**
-
-open.c
-
-**Processing:**
-
-This routine is layered on both RTEMS calls and filesystem specific
-implementations of the open() function. These functional interfaces should
-not change for new filesystems and therefore this code should be stable as
-new file systems are introduced.
-
-**Development Comments:**
-
-This routine will allocate a file control block for the file or device
-that we are about to open.
-
-It will then test to see if the pathname exists. If it does a
-rtems_filesystem_location_info_t data structure will be filled out. This
-structure contains information that associates node information,
-filesystem specific functions and mount table chain information with the
-pathname.
-
-If the create option has been it will attempt to create a node for a
-regular file along the specified path. If a file already exists along this
-path, an error will be generated; otherwise, a node will be allocated for
-the file under the filesystem that contains the pathname. When a new node
-is created, it is also evaluated so that an appropriate
-rtems_filesystem_location_info_t data structure can be filled out for the
-newly created node.
-
-If the file exists or the new file was created successfully, the file
-control block structure will be initialized with handler table
-information, node information and the rtems_filesystem_location_info_t
-data structure that describes the node and filesystem data in detail.
-
-If an open() function exists in the filesystem specific handlers table for
-the node that we are trying to open, it will be called at this time.
-
-If any error is detected in the process, cleanup is performed. It consists
-of freeing the file control block structure that was allocated at the
-beginning of the generic open() routine.
-
-On a successful open(), the index into the file descriptor table will be
-calculated and returned to the calling routine.
-
-.. COMMENT: @page
-
-opendir
-=======
-
-**File:**
-
-opendir.c
-
-**Processing:**
-
-This routine will attempt to open a directory for read access. It will
-setup a DIR control structure that will be used to access directory
-information. This routine is layered on the generic open() routine and
-filesystem specific directory processing routines.
-
-**Development Comments:**
-
-The BSD group provided this routine.
-
-.. COMMENT: @page
-
-pathconf
-========
-
-**File:**
-
-pathconf.c
-
-**Processing:**
-
-This routine will obtain the value of one of the path configuration
-parameters and return it to the calling routine. It is layered on the
-generic open() and fpathconf() functions. These interfaces should not
-change with the addition of new filesystem types.
-
-**Development Comments:**
-
-This routine will try to open the file indicated by path.
-
-If successful, the file descriptor will be used to access the pathconf
-value specified by ``name`` using the fpathconf() function.
-
-The file that was accessed is then closed.
-
-.. COMMENT: @page
-
-read
-====
-
-**File:**
-
-deviceio.c
-
-**Processing:**
-
-This routine is layered on a set of RTEMS calls and filesystem specific
-read operations. The functions are layered in such a way as to isolate
-them from change as new filesystems are introduced.
-
-**Development Comments:**
-
-This routine will examine the type of file descriptor it is sent.
-
-If the file descriptor is associated with a network device, the read
-function will be mapped to a special network handler. The return code from
-the network handler will then be sent as the return code from generic
-read() function.
-
-For file descriptors that are associated with the filesystem the following
-sequence will be performed:
-
-# Obtain the file control block associated with the file descriptor
-
-# Range check the file descriptor
-
-# Determine that the buffer pointer is not invalid
-
-# Check that the count is not zero
-
-# Check the file control block to see if we have permissions to read
-
-# If there is a read function in the handler table, invoke the handler
- table read() function
-
-# Use the return code from the handler table read function(number of
- bytes read) to increment the offset element of the file control block
-
-# Return the number of bytes read to the calling program
-
-.. COMMENT: @page
-
-readdir
-=======
-
-**File:**
-
-readdir.c
-
-**Processing:**
-
-This routine was acquired from the BSD group. It has not been altered from
-its original form.
-
-**Development Comments:**
-
-The routine calls a customized getdents() function that is provided by the
-user. This routine provides the filesystem specific aspects of reading a
-directory.
-
-It is layered on the read() function in the directory handler table. This
-function has been mapped to the Imfs_dir_read() function.
-
-.. COMMENT: @page
-
-unmount
-=======
-
-**File:**
-
-unmount.c
-
-**Processing:**
-
-This routine will attempt to dismount a mounted filesystem and then free
-all resources that were allocated for the management of that filesystem.
-
-**Development Comments:**
-
-- This routine will determine if there are any filesystems currently
- mounted under the filesystem that we are trying to dismount. This would
- prevent the dismount of the filesystem.
-
-- It will test to see if the current directory is in the filesystem
- that we are attempting to dismount. This would prevent the dismount of the
- filesystem.
-
-- It will scan all the currently open file descriptors to determine is
- there is an open file descriptor to a file in the filesystem that we are
- attempting to unmount().
-
-If the above preconditions are met then the following sequence is
-performed:
-
-# Call the filesystem specific unmount() function for the filesystem
- that contains the mount point. This routine should indicate that the mount
- point no longer has a filesystem mounted below it.
-
-# Call the filesystem specific fsunmount_me() function for the mounted
- filesystem that we are trying to unmount(). This routine should clean up
- any resources that are no longer needed for the management of the file
- system being un-mounted.
-
-# Extract the mount table entry for the filesystem that was just
- dismounted from the mount table chain.
-
-# Free the memory associated with the extracted mount table entry.
-
-.. COMMENT: @page
-
-eval
-====
-
-**File:**
-
-XXX
-
-**Processing:**
-
-XXX
-
-**Development Comments:**
-
-XXX
-
-.. COMMENT: @page
-
-getdentsc
-=========
-
-**File:**
-
-XXX
-
-**Processing:**
-
-XXX
-
-**Development Comments:**
-
-XXX
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-Filesystem Implementation Requirements
-######################################
-
-This chapter details the behavioral requirements that all filesystem
-implementations must adhere to.
-
-General
-=======
-
-The RTEMS filesystem framework was intended to be compliant with the
-POSIX Files and Directories interface standard. The following filesystem
-characteristics resulted in a functional switching layer.
-.. code:: c
-
- Figure of the Filesystem Functional Layering goes here.
- This figure includes networking and disk caching layering.
-
-# Application programs are presented with a standard set of POSIX
- compliant functions that allow them to interface with the files, devices
- and directories in the filesystem. The interfaces to these routines do
- not reflect the type of subordinate filesystem implementation in which
- the file will be found.
-
-# The filesystem framework developed under RTEMS allows for mounting
- filesystem of different types under the base filesystem.
-
-# The mechanics of locating file information may be quite different
- between filesystem types.
-
-# The process of locating a file may require crossing filesystem
- boundaries.
-
-# The transitions between filesystem and the processing required to
- access information in different filesystem is not visible at the level
- of the POSIX function call.
-
-# The POSIX interface standard provides file access by character
- pathname to the file in some functions and through an integer file
- descriptor in other functions.
-
-# The nature of the integer file descriptor and its associated
- processing is operating system and filesystem specific.
-
-# Directory and device information must be processed with some of the
- same routines that apply to files.
-
-# The form and content of directory and device information differs
- greatly from that of a regular file.
-
-# Files, directories and devices represent elements (nodes) of a tree
- hierarchy.
-
-# The rules for processing each of the node types that exist under the
- filesystem are node specific but are still not reflected in the POSIX
- interface routines.
-
-.. code:: c
-
- Figure of the Filesystem Functional Layering goes here.
- This figure focuses on the Base Filesystem and IMFS.
-
-.. code:: c
-
- Figure of the IMFS Memfile control blocks
-
-
-File and Directory Removal Constraints
-======================================
-
-The following POSIX constraints must be honored by all filesystems.
-
-- If a node is a directory with children it cannot be removed.
-
-- The root node of any filesystem, whether the base filesystem or a
- mounted filesystem, cannot be removed.
-
-- A node that is a directory that is acting as the mount point of a file
- system cannot be removed.
-
-- On filesystems supporting hard links, a link count is maintained.
- Prior to node removal, the node’s link count is decremented by one. The
- link count must be less than one to allow for removal of the node.
-
-API Layering
-============
-
-Mapping of Generic System Calls to Filesystem Specific Functions
-----------------------------------------------------------------
-
-The list of generic system calls includes the routines open(), read(),
-write(), close(), etc..
-
-The Files and Directories section of the POSIX Application Programs
-Interface specifies a set of functions with calling arguments that are
-used to gain access to the information in a filesystem. To the
-application program, these functions allow access to information in any
-mounted filesystem without explicit knowledge of the filesystem type or
-the filesystem mount configuration. The following are functions that are
-provided to the application:
-
-# access()
-
-# chdir()
-
-# chmod()
-
-# chown()
-
-# close()
-
-# closedir()
-
-# fchmod()
-
-# fcntl()
-
-# fdatasync()
-
-# fpathconf()
-
-# fstat()
-
-# fsync()
-
-# ftruncate()
-
-# link()
-
-# lseek()
-
-# mkdir()
-
-# mknod()
-
-# mount()
-
-# open()
-
-# opendir()
-
-# pathconf()
-
-# read()
-
-# readdir()
-
-# rewinddir()
-
-# rmdir()
-
-# rmnod()
-
-# scandir()
-
-# seekdir()
-
-# stat()
-
-# telldir()
-
-# umask()
-
-# unlink()
-
-# unmount()
-
-# utime()
-
-# write()
-
-The filesystem’s type as well as the node type within the filesystem
-determine the nature of the processing that must be performed for each of
-the functions above. The RTEMS filesystem provides a framework that
-allows new filesystem to be developed and integrated without alteration
-to the basic framework.
-
-To provide the functional switching that is required, each of the POSIX
-file and directory functions have been implemented as a shell function.
-The shell function adheres to the POSIX interface standard. Within this
-functional shell, filesystem and node type information is accessed which
-is then used to invoke the appropriate filesystem and node type specific
-routine to process the POSIX function call.
-
-File/Device/Directory function access via file control block - rtems_libio_t structure
---------------------------------------------------------------------------------------
-
-The POSIX open() function returns an integer file descriptor that is used
-as a reference to file control block information for a specific file. The
-file control block contains information that is used to locate node, file
-system, mount table and functional handler information. The diagram in
-Figure 8 depicts the relationship between and among the following
-components.
-
-# File Descriptor Table
- This is an internal RTEMS structure that tracks all currently defined file
- descriptors in the system. The index that is returned by the file open()
- operation references a slot in this table. The slot contains a pointer to
- the file descriptor table entry for this file. The rtems_libio_t structure
- represents the file control block.
-
-# Allocation of entry in the File Descriptor Table
- Access to the file descriptor table is controlled through a semaphore that
- is implemented using the rtems_libio_allocate() function. This routine
- will grab a semaphore and then scan the file control blocks to determine
- which slot is free for use. The first free slot is marked as used and the
- index to this slot is returned as the file descriptor for the open()
- request. After the alterations have been made to the file control block
- table, the semaphore is released to allow further operations on the table.
-
-# Maximum number of entries in the file descriptor table is
- configurable through the src/exec/sapi/headers/confdefs.h file. If the
- CONFIGURE_LIBIO_MAXIMUM_FILE_DESCRIPTORS constant is defined its value
- will represent the maximum number of file descriptors that are allowed.
- If CONFIGURE_LIBIO_MAXIMUM_FILE_DESCRIPTORS is not specified a default
- value of 20 will be used as the maximum number of file descriptors
- allowed.
-
-# File control block - rtems_libio_t structure
-
- .. code:: c
-
- struct rtems_libio_tt {
- rtems_driver_name_t \*driver;
- off_t size;
- off_t offset;
- unsigned32 flags;
- rtems_filesystem_location_info_t pathinfo;
- Objects_Id sem;
- unsigned32 data0;
- void data1;
- void file_info;
- rtems_filesystem_file_handlers_r handlers;
- };
-
- A file control block can exist for regular files, devices and directories.
- The following fields are important for regular file and directory access:
-
- - Size - For a file this represents the number of bytes currently
- stored in a file. For a directory this field is not filled in.
-
- - Offset - For a file this is the byte file position index relative to
- the start of the file. For a directory this is the byte offset into a
- sequence of dirent structures.
-
- - Pathinfo - This is a structure that provides a pointer to node
- information, OPS table functions, Handler functions and the mount table
- entry associated with this node.
-
- - file_info - A pointer to node information that is used by Handler
- functions
-
- - handlers - A pointer to a table of handler functions that operate on
- a file, device or directory through a file descriptor index
-
-File/Directory function access via rtems_filesystem_location_info_t structure
------------------------------------------------------------------------------
-
-The rtems_filesystem_location_info_tt structure below provides sufficient
-information to process nodes under a mounted filesystem.
-
-.. code:: c
-
- struct rtems_filesystem_location_info_tt {
- void \*node_access;
- rtems_filesystem_file_handlers_r \*handlers;
- rtems_filesystem_operations_table \*ops;
- rtems_filesystem_mount_table_entry_t \*mt_entry;
- };
-
-It contains a void pointer to filesystem specific nodal structure,
-pointers to the OPS table for the filesystem that contains the node, the
-node type specific handlers for the node and a reference pointer to the
-mount table entry associated with the filesystem containing the node
-
-Operation Tables
-================
-
-Filesystem specific operations are invoked indirectly. The set of
-routines that implement the filesystem are configured into two tables.
-The Filesystem Handler Table has routines that are specific to a
-filesystem but remain constant regardless of the actual file type.
-The File Handler Table has routines that are both filesystem and file type
-specific.
-
-Filesystem Handler Table Functions
-----------------------------------
-
-OPS table functions are defined in a ``rtems_filesystem_operations_table``
-structure. It defines functions that are specific to a given filesystem.
-One table exists for each filesystem that is supported in the RTEMS
-configuration. The structure definition appears below and is followed by
-general developmental information on each of the functions contained in this
-function management structure.
-
-.. code:: c
-
- typedef struct {
- rtems_filesystem_evalpath_t evalpath;
- rtems_filesystem_evalmake_t evalformake;
- rtems_filesystem_link_t link;
- rtems_filesystem_unlink_t unlink;
- rtems_filesystem_node_type_t node_type;
- rtems_filesystem_mknod_t mknod;
- rtems_filesystem_rmnod_t rmnod;
- rtems_filesystem_chown_t chown;
- rtems_filesystem_freenode_t freenod;
- rtems_filesystem_mount_t mount;
- rtems_filesystem_fsmount_me_t fsmount_me;
- rtems_filesystem_unmount_t unmount;
- rtems_filesystem_fsunmount_me_t fsunmount_me;
- rtems_filesystem_utime_t utime;
- rtems_filesystem_evaluate_link_t eval_link;
- rtems_filesystem_symlink_t symlink;
- } rtems_filesystem_operations_table;
-
-.. COMMENT: @page
-
-evalpath Handler
-~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-evalpath
-
-**Arguments:**
-
-.. code:: c
-
- const char \*pathname, /* IN \*/
- int flags, /* IN \*/
- rtems_filesystem_location_info_t \*pathloc /* IN/OUT \*/
-
-**Description:**
-
-This routine is responsible for evaluating the pathname passed in
-based upon the flags and the valid ``rthems_filesystem_location_info_t``.
-Additionally, it must make any changes to pathloc necessary to identify
-the pathname node. This should include calling the evalpath for a mounted
-filesystem, if the given filesystem supports the mount command.
-
-This routine returns a 0 if the evaluation was successful.
-Otherwise, it returns a -1 and sets errno to the correct error.
-
-This routine is required and should NOT be set to NULL.
-
-.. COMMENT: @page
-
-evalformake Handler
-~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-evalformake
-
-**Arguments:**
-
-.. code:: c
-
- const char \*path, /* IN \*/
- rtems_filesystem_location_info_t \*pathloc, /* IN/OUT \*/
- const char \**name /* OUT \*/
-
-**Description:**
-
-This method is given a path to evaluate and a valid start location. It
-is responsible for finding the parent node for a requested make command,
-setting pathloc information to identify the parent node, and setting
-the name pointer to the first character of the name of the new node.
-Additionally, if the filesystem supports the mount command, this method
-should call the evalformake routine for the mounted filesystem.
-
-This routine returns a 0 if the evaluation was successful. Otherwise, it
-returns a -1 and sets errno to the correct error.
-
-This routine is required and should NOT be set to NULL. However, if
-the filesystem does not support user creation of a new node, it may
-set errno to ENOSYS and return -1.
-
-.. COMMENT: @page
-
-link Handler
-~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-link
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*to_loc, /* IN \*/
- rtems_filesystem_location_info_t \*parent_loc, /* IN \*/
- const char \*token /* IN \*/
-
-**Description:**
-
-This routine is used to create a hard-link.
-
-It will first examine the st_nlink count of the node that we are trying to.
-If the link count exceeds LINK_MAX an error will be returned.
-
-The name of the link will be normalized to remove extraneous separators from
-the end of the name.
-
-This routine is not required and may be set to NULL.
-
-.. COMMENT: @page
-
-unlink Handler
-~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-node_type Handler
-~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-node_type()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*pathloc /* IN \*/
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-mknod Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-mknod()
-
-**Arguments:**
-
-.. code:: c
-
- const char \*token, /* IN \*/
- mode_t mode, /* IN \*/
- dev_t dev, /* IN \*/
- rtems_filesystem_location_info_t \*pathloc /* IN/OUT \*/
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-rmnod Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-chown Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-chown()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*pathloc /* IN \*/
- uid_t owner /* IN \*/
- gid_t group /* IN \*/
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-freenod Handler
-~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-freenod()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*pathloc /* IN \*/
-
-**Description:**
-
-This routine is used by the generic code to allow memory to be allocated
-during the evaluate routines, and set free when the generic code is finished
-accessing a node. If the evaluate routines allocate memory to identify
-a node this routine should be utilized to free that memory.
-
-This routine is not required and may be set to NULL.
-
-.. COMMENT: @page
-
-mount Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-mount()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_mount_table_entry_t \*mt_entry
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-fsmount_me Handler
-~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_mount_table_entry_t \*mt_entry
-
-**Description:**
-
-This function is provided with a filesystem to take care of the internal
-filesystem management details associated with mounting that filesystem
-under the RTEMS environment.
-
-It is not responsible for the mounting details associated the filesystem
-containing the mount point.
-
-The rtems_filesystem_mount_table_entry_t structure contains the key elements
-below:
-
-rtems_filesystem_location_info_t \*mt_point_node,
-
-This structure contains information about the mount point. This
-allows us to find the ops-table and the handling functions
-associated with the filesystem containing the mount point.
-
-rtems_filesystem_location_info_t \*fs_root_node,
-
-This structure contains information about the root node in the file
-system to be mounted. It allows us to find the ops-table and the
-handling functions associated with the filesystem to be mounted.
-
-rtems_filesystem_options_t options,
-
-Read only or read/write access
-
-void \*fs_info,
-
-This points to an allocated block of memory the will be used to
-hold any filesystem specific information of a global nature. This
-allocated region if important because it allows us to mount the
-same filesystem type more than once under the RTEMS system.
-Each instance of the mounted filesystem has its own set of global
-management information that is separate from the global
-management information associated with the other instances of the
-mounted filesystem type.
-
-rtems_filesystem_limits_and_options_t pathconf_info,
-
-The table contains the following set of values associated with the
-mounted filesystem:
-
-- link_max
-
-- max_canon
-
-- max_input
-
-- name_max
-
-- path_max
-
-- pipe_buf
-
-- posix_async_io
-
-- posix_chown_restrictions
-
-- posix_no_trunc
-
-- posix_prio_io
-
-- posix_sync_io
-
-- posix_vdisable
-
-These values are accessed with the pathconf() and the fpathconf ()
-functions.
-
-const char \*dev
-
-The is intended to contain a string that identifies the device that contains
-the filesystem information. The filesystems that are currently implemented
-are memory based and don’t require a device specification.
-
-If the mt_point_node.node_access is NULL then we are mounting the base file
-system.
-
-The routine will create a directory node for the root of the IMFS file
-system.
-
-The node will have read, write and execute permissions for owner, group and
-others.
-
-The node’s name will be a null string.
-
-A filesystem information structure(fs_info) will be allocated and
-initialized for the IMFS filesystem. The fs_info pointer in the mount table
-entry will be set to point the filesystem information structure.
-
-The pathconf_info element of the mount table will be set to the appropriate
-table of path configuration constants (LIMITS_AND_OPTIONS).
-
-The fs_root_node structure will be filled in with the following:
-
-- pointer to the allocated root node of the filesystem
-
-- directory handlers for a directory node under the IMFS filesystem
-
-- OPS table functions for the IMFS
-
-A 0 will be returned to the calling routine if the process succeeded,
-otherwise a 1 will be returned.
-
-.. COMMENT: @page
-
-unmount Handler
-~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-fsunmount_me Handler
-~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-imfs_fsunmount_me()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_mount_table_entry_t \*mt_entry
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-utime Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-eval_link Handler
-~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-symlink Handler
-~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-File Handler Table Functions
-----------------------------
-
-Handler table functions are defined in a ``rtems_filesystem_file_handlers_r``
-structure. It defines functions that are specific to a node type in a given
-filesystem. One table exists for each of the filesystem’s node types. The
-structure definition appears below. It is followed by general developmental
-information on each of the functions associated with regular files contained
-in this function management structure.
-.. code:: c
-
- typedef struct {
- rtems_filesystem_open_t open;
- rtems_filesystem_close_t close;
- rtems_filesystem_read_t read;
- rtems_filesystem_write_t write;
- rtems_filesystem_ioctl_t ioctl;
- rtems_filesystem_lseek_t lseek;
- rtems_filesystem_fstat_t fstat;
- rtems_filesystem_fchmod_t fchmod;
- rtems_filesystem_ftruncate_t ftruncate;
- rtems_filesystem_fpathconf_t fpathconf;
- rtems_filesystem_fsync_t fsync;
- rtems_filesystem_fdatasync_t fdatasync;
- rtems_filesystem_fcntl_t fcntl;
- } rtems_filesystem_file_handlers_r;
-
-.. COMMENT: @page
-
-open Handler
-~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-open()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- const char \*pathname,
- unsigned32 flag,
- unsigned32 mode
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-close Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-close()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: @page
-
-read Handler
-~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-read()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- void \*buffer,
- unsigned32 count
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: @page
-
-write Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: @page
-
-ioctl Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- unsigned32 command,
- void \*buffer
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: @page
-
-lseek Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-lseek()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- off_t offset,
- int whence
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: @page
-
-fstat Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-fstat()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*loc,
- struct stat \*buf
-
-**Description:**
-
-The following information is extracted from the filesystem
-specific node and placed in the ``stat`` structure:
-
-- st_mode
-
-- st_nlink
-
-- st_ino
-
-- st_uid
-
-- st_gid
-
-- st_atime
-
-- st_mtime
-
-- st_ctime
-
-**NOTES:**
-
-Both the ``stat()`` and ``lstat()`` services are
-implemented directly using the ``fstat()`` handler. The
-difference in behavior is determined by how the path is evaluated
-prior to this handler being called on a particular
-file entity.
-
-The ``fstat()`` system call is implemented directly
-on top of this filesystem handler.
-
-.. COMMENT: @page
-
-fchmod Handler
-~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-fchmod()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop
- mode_t mode
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: @page
-
-ftruncate Handler
-~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-fpathconf Handler
-~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: @page
-
-fsync Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: @page
-
-fdatasync Handler
-~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: @page
-
-fcntl Handler
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**Description:**
-
-XXX
-
-**NOTES:**
-
-XXX
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-In-Memory Filesystem
-####################
-
-This chapter describes the In-Memory FileSystem (IMFS). The IMFS is a
-full featured POSIX filesystem that keeps all information in memory.
-
-IMFS Per Node Data Structure
-============================
-
-Each regular file, device, hard link, and directory is represented by a data
-structure called a ``jnode``. The ``jnode`` is formally represented by the
-structure:
-.. code:: c
-
- struct IMFS_jnode_tt {
- Chain_Node Node; /* for chaining them together \*/
- IMFS_jnode_t \*Parent; /* Parent node \*/
- char name[NAME_MAX+1]; /* "basename" \*/
- mode_t st_mode; /* File mode \*/
- nlink_t st_nlink; /* Link count \*/
- ino_t st_ino; /* inode \*/
- uid_t st_uid; /* User ID of owner \*/
- gid_t st_gid; /* Group ID of owner \*/
- time_t st_atime; /* Time of last access \*/
- time_t st_mtime; /* Time of last modification \*/
- time_t st_ctime; /* Time of last status change \*/
- IMFS_jnode_types_t type; /* Type of this entry \*/
- IMFS_typs_union info;
- };
-
-The key elements of this structure are listed below together with a brief
-explanation of their role in the filesystem.
-
-*Node*
- exists to allow the entire ``jnode`` structure to be included in a chain.
-
-*Parent*
- is a pointer to another ``jnode`` structure that is the logical parent of the
- node in which it appears. This field may be NULL if the file associated with
- this node is deleted but there are open file descriptors on this file or
- there are still hard links to this node.
-
-*name*
- is the name of this node within the filesystem hierarchical tree. Example: If
- the fully qualified pathname to the ``jnode`` was ``/a/b/c``, the``jnode`` name field would contain the null terminated string ``"c"``.
-
-*st_mode*
- is the standard Unix access permissions for the file or directory.
-
-*st_nlink*
- is the number of hard links to this file. When a ``jnode`` is first created
- its link count is set to 1. A ``jnode`` and its associated resources
- cannot be deleted unless its link count is less than 1.
-
-*st_ino*
- is a unique node identification number
-
-*st_uid*
- is the user ID of the file’s owner
-
-*st_gid*
- is the group ID of the file’s owner
-
-*st_atime*
- is the time of the last access to this file
-
-*st_mtime*
- is the time of the last modification of this file
-
-*st_ctime*
- is the time of the last status change to the file
-
-*type*
- is the indication of node type must be one of the following states:
- - IMFS_DIRECTORY
- - IMFS_MEMORY_FILE
- - IMFS_HARD_LINK
- - IMFS_SYM_LINK
- - IMFS_DEVICE
-
-*info*
- is this contains a structure that is unique to file type (See IMFS_typs_union
- in imfs.h).
-
- - IMFS_DIRECTORY
-
- An IMFS directory contains a dynamic chain structure that
- records all files and directories that are subordinate to the directory node.
-
- - IMFS_MEMORY_FILE
-
- Under the in memory filesystem regular files hold data. Data is dynamically
- allocated to the file in 128 byte chunks of memory. The individual chunks of
- memory are tracked by arrays of pointers that record the address of the
- allocated chunk of memory. Single, double, and triple indirection pointers
- are used to record the locations of all segments of the file. The
- memory organization of an IMFS file are discussed elsewhere in this manual.
-
- - IMFS_HARD_LINK
-
- The IMFS filesystem supports the concept of hard links to other nodes in the
- IMFS filesystem. These hard links are actual pointers to other nodes in the
- same filesystem. This type of link cannot cross-filesystem boundaries.
-
- - IMFS_SYM_LINK
-
- The IMFS filesystem supports the concept of symbolic links to other nodes in
- any filesystem. A symbolic link consists of a pointer to a character string
- that represents the pathname to the target node. This type of link can
- cross-filesystem boundaries. Just as with most versions of UNIX supporting
- symbolic links, a symbolic link can point to a non-existent file.
-
- - IMFS_DEVICE
-
- All RTEMS devices now appear as files under the in memory filesystem. On
- system initialization, all devices are registered as nodes under the file
- system.
-
-Miscellaneous IMFS Information
-==============================
-
-Memory associated with the IMFS
-===============================
-
-A memory based filesystem draws its resources for files and directories
-from the memory resources of the system. When it is time to un-mount the
-filesystem, the memory resources that supported filesystem are set free.
-In order to free these resources, a recursive walk of the filesystems
-tree structure will be performed. As the leaf nodes under the filesystem
-are encountered their resources are freed. When directories are made empty
-by this process, their resources are freed.
-
-Node removal constraints for the IMFS
--------------------------------------
-
-The IMFS conforms to the general filesystem requirements for node
-removal. See `File and Directory Removal Constraints`_.
-
-IMFS General Housekeeping Notes
--------------------------------
-
-The following is a list of odd housekeeping notes for the IMFS.
-
-- If the global variable rtems_filesystem_current refers to the node that
- we are trying to remove, the node_access element of this structure must be
- set to NULL to invalidate it.
-
-- If the node was of IMFS_MEMORY_FILE type, free the memory associated
- with the memory file before freeing the node. Use the IMFS_memfile_remove()
- function.
-
-IMFS Operation Tables
-=====================
-
-IMFS Filesystem Handler Table Functions
----------------------------------------
-
-OPS table functions are defined in a rtems_filesystem_operations_table
-structure. It defines functions that are specific to a given filesystem.
-One table exists for each filesystem that is supported in the RTEMS
-configuration. The structure definition appears below and is followed by
-general developmental information on each of the functions contained in this
-function management structure.
-.. code:: c
-
- rtems_filesystem_operations_table IMFS_ops = {
- IMFS_eval_path,
- IMFS_evaluate_for_make,
- IMFS_link,
- IMFS_unlink,
- IMFS_node_type,
- IMFS_mknod,
- IMFS_rmnod,
- IMFS_chown,
- IMFS_freenodinfo,
- IMFS_mount,
- IMFS_initialize,
- IMFS_unmount,
- IMFS_fsunmount,
- IMFS_utime,
- IMFS_evaluate_link,
- IMFS_symlink,
- IMFS_readlink
- };
-
-.. COMMENT: @page
-
-IMFS_evalpath()
-~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-IMFS_evalformake()
-~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-IMFS_link()
-~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-link
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*to_loc, /* IN \*/
- rtems_filesystem_location_info_t \*parent_loc, /* IN \*/
- const char \*token /* IN \*/
-
-**File:**
-
-imfs_link.c
-
-**Description:**
-
-This routine is used in the IMFS filesystem to create a hard-link.
-
-It will first examine the st_nlink count of the node that we are trying to.
-If the link count exceeds LINK_MAX an error will be returned.
-
-The name of the link will be normalized to remove extraneous separators from
-the end of the name.
-
-IMFS_create_node will be used to create a filesystem node that will have the
-following characteristics:
-
-- parent that was determined in the link() function in file link.c
-
-- Type will be set to IMFS_HARD_LINK
-
-- name will be set to the normalized name
-
-- mode of the hard-link will be set to the mode of the target node
-
-If there was trouble allocating memory for the new node an error will be
-returned.
-
-The st_nlink count of the target node will be incremented to reflect the new
-link.
-
-The time fields of the link will be set to reflect the creation time of the
-hard-link.
-
-.. COMMENT: @page
-
-IMFS_unlink()
-~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-IMFS_node_type()
-~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_node_type()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*pathloc /* IN \*/
-
-**File:**
-
-imfs_ntype.c
-
-**Description:**
-
-This routine will locate the IMFS_jnode_t structure that holds ownership
-information for the selected node in the filesystem.
-
-This structure is pointed to by pathloc->node_access.
-
-The IMFS_jnode_t type element indicates one of the node types listed below:
-
-- RTEMS_FILESYSTEM_DIRECTORY
-
-- RTEMS_FILESYSTEM_DEVICE
-
-- RTEMS_FILESYSTEM_HARD_LINK
-
-- RTEMS_FILESYSTEM_MEMORY_FILE
-
-.. COMMENT: @page
-
-IMFS_mknod()
-~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_mknod()
-
-**Arguments:**
-
-.. code:: c
-
- const char \*token, /* IN \*/
- mode_t mode, /* IN \*/
- dev_t dev, /* IN \*/
- rtems_filesystem_location_info_t \*pathloc /* IN/OUT \*/
-
-**File:**
-
-imfs_mknod.c
-
-**Description:**
-
-This routine will examine the mode argument to determine is we are trying to
-create a directory, regular file and a device node. The creation of other
-node types is not permitted and will cause an assert.
-
-Memory space will be allocated for a ``jnode`` and the node will be set up
-according to the nodal type that was specified. The IMFS_create_node()
-function performs the allocation and setup of the node.
-
-The only problem that is currently reported is the lack of memory when we
-attempt to allocate space for the ``jnode`` (ENOMEN).
-
-.. COMMENT: @page
-
-IMFS_rmnod()
-~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-IMFS_chown()
-~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_chown()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*pathloc /* IN \*/
- uid_t owner /* IN \*/
- gid_t group /* IN \*/
-
-**File:**
-
-imfs_chown.c
-
-**Description:**
-
-This routine will locate the IMFS_jnode_t structure that holds ownership
-information for the selected node in the filesystem.
-
-This structure is pointed to by pathloc->node_access.
-
-The st_uid and st_gid fields of the node are then modified. Since this is a
-memory based filesystem, no further action is required to alter the
-ownership of the IMFS_jnode_t structure.
-
-.. COMMENT: @page
-
-IMFS_freenod()
-~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_freenod()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*pathloc /* IN \*/
-
-**File:**
-
-imfs_free.c
-
-**Description:**
-
-This method is a private function to the IMFS. It is called by IMFS routines
-to free nodes that have been allocated. Examples of where this routine
-may be called from are unlink and rmnod.
-
-Note: This routine should not be confused with the filesystem callback
-freenod. The IMFS allocates memory until the node no longer exists.
-
-.. COMMENT: @page
-
-IMFS_freenodinfo()
-~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_freenodinfo()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*pathloc /* IN \*/
-
-**File:**
-
-imfs_free.c
-
-**Description:**
-
-The In-Memory File System does not need to allocate memory during the
-evaluate routines. Therefore, this routine simply routines PASS.
-
-.. COMMENT: @page
-
-IMFS_mount()
-~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_mount()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_mount_table_entry_t \*mt_entry
-
-**File:**
-
-imfs_mount.c
-
-**Description:**
-
-This routine provides the filesystem specific processing required to mount a
-filesystem for the system that contains the mount point. It will determine
-if the point that we are trying to mount onto is a node of IMFS_DIRECTORY
-type.
-
-If it is the node’s info element is altered so that the info.directory.mt_fs
-element points to the mount table chain entry that is associated with the
-mounted filesystem at this point. The info.directory.mt_fs element can be
-examined to determine if a filesystem is mounted at a directory. If it is
-NULL, the directory does not serve as a mount point. A non-NULL entry
-indicates that the directory does serve as a mount point and the value of
-info.directory.mt_fs can be used to locate the mount table chain entry that
-describes the filesystem mounted at this point.
-
-.. COMMENT: @page
-
-IMFS_fsmount_me()
-~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_initialize()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_mount_table_entry_t \*mt_entry
-
-**File:**
-
-imfs_init.c
-
-**Description:**
-
-This function is provided with a filesystem to take care of the internal
-filesystem management details associated with mounting that filesystem
-under the RTEMS environment.
-
-It is not responsible for the mounting details associated the filesystem
-containing the mount point.
-
-The rtems_filesystem_mount_table_entry_t structure contains the key elements
-below:
-
-rtems_filesystem_location_info_t \*mt_point_node,
-
-This structure contains information about the mount point. This
-allows us to find the ops-table and the handling functions
-associated with the filesystem containing the mount point.
-
-rtems_filesystem_location_info_t \*fs_root_node,
-
-This structure contains information about the root node in the file
-system to be mounted. It allows us to find the ops-table and the
-handling functions associated with the filesystem to be mounted.
-
-rtems_filesystem_options_t options,
-
-Read only or read/write access
-
-void \*fs_info,
-
-This points to an allocated block of memory the will be used to
-hold any filesystem specific information of a global nature. This
-allocated region if important because it allows us to mount the
-same filesystem type more than once under the RTEMS system.
-Each instance of the mounted filesystem has its own set of global
-management information that is separate from the global
-management information associated with the other instances of the
-mounted filesystem type.
-
-rtems_filesystem_limits_and_options_t pathconf_info,
-
-The table contains the following set of values associated with the
-mounted filesystem:
-
-- link_max
-
-- max_canon
-
-- max_input
-
-- name_max
-
-- path_max
-
-- pipe_buf
-
-- posix_async_io
-
-- posix_chown_restrictions
-
-- posix_no_trunc
-
-- posix_prio_io
-
-- posix_sync_io
-
-- posix_vdisable
-
-These values are accessed with the pathconf() and the fpathconf ()
-functions.
-
-const char \*dev
-
-The is intended to contain a string that identifies the device that contains
-the filesystem information. The filesystems that are currently implemented
-are memory based and don’t require a device specification.
-
-If the mt_point_node.node_access is NULL then we are mounting the base file
-system.
-
-The routine will create a directory node for the root of the IMFS file
-system.
-
-The node will have read, write and execute permissions for owner, group and
-others.
-
-The node’s name will be a null string.
-
-A filesystem information structure(fs_info) will be allocated and
-initialized for the IMFS filesystem. The fs_info pointer in the mount table
-entry will be set to point the filesystem information structure.
-
-The pathconf_info element of the mount table will be set to the appropriate
-table of path configuration constants ( IMFS_LIMITS_AND_OPTIONS ).
-
-The fs_root_node structure will be filled in with the following:
-
-- pointer to the allocated root node of the filesystem
-
-- directory handlers for a directory node under the IMFS filesystem
-
-- OPS table functions for the IMFS
-
-A 0 will be returned to the calling routine if the process succeeded,
-otherwise a 1 will be returned.
-
-.. COMMENT: @page
-
-IMFS_unmount()
-~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_unmount()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_mount_table_entry_t \*mt_entry
-
-**File:**
-
-imfs_unmount.c
-
-**Description:**
-
-This routine allows the IMFS to unmount a filesystem that has been
-mounted onto a IMFS directory.
-
-The mount entry mount point node access is verified to be a mounted
-directory. It’s mt_fs is set to NULL. This identifies to future
-calles into the IMFS that this directory node is no longer a mount
-point. Additionally, it will allow any directories that were hidden
-by the mounted system to again become visible.
-
-.. COMMENT: @page
-
-IMFS_fsunmount()
-~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-imfs_fsunmount()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_mount_table_entry_t \*mt_entry
-
-**File:**
-
-imfs_init.c
-
-**Description:**
-
-This method unmounts this instance of the IMFS file system. It is the
-counterpart to the IMFS_initialize routine. It is called by the generic
-code under the fsunmount_me callback.
-
-All method loops finding the first encountered node with no children and
-removing the node from the tree, thus returning allocated resources. This
-is done until all allocated nodes are returned.
-
-.. COMMENT: @page
-
-IMFS_utime()
-~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-IMFS_eval_link()
-~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-Regular File Handler Table Functions
-------------------------------------
-
-Handler table functions are defined in a rtems_filesystem_file_handlers_r
-structure. It defines functions that are specific to a node type in a given
-filesystem. One table exists for each of the filesystem’s node types. The
-structure definition appears below. It is followed by general developmental
-information on each of the functions associated with regular files contained
-in this function management structure.
-.. code:: c
-
- rtems_filesystem_file_handlers_r IMFS_memfile_handlers = {
- memfile_open,
- memfile_close,
- memfile_read,
- memfile_write,
- memfile_ioctl,
- memfile_lseek,
- IMFS_stat,
- IMFS_fchmod,
- memfile_ftruncate,
- NULL, /* fpathconf \*/
- NULL, /* fsync \*/
- IMFS_fdatasync,
- IMFS_fcntl
- };
-
-.. COMMENT: @page
-
-memfile_open() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-memfile_open()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- const char \*pathname,
- unsigned32 flag,
- unsigned32 mode
-
-**File:**
-
-memfile.c
-
-**Description:**
-
-Currently this function is a shell. No meaningful processing is performed and
-a success code is always returned.
-
-.. COMMENT: @page
-
-memfile_close() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-memfile_close()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop
-
-**File:**
-
-memfile.c
-
-**Description:**
-
-This routine is a dummy for regular files under the base filesystem. It
-performs a capture of the IMFS_jnode_t pointer from the file control block
-and then immediately returns a success status.
-
-.. COMMENT: @page
-
-memfile_read() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-memfile_read()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- void \*buffer,
- unsigned32 count
-
-**File:**
-
-memfile.c
-
-**Description:**
-
-This routine will determine the ``jnode`` that is associated with this file.
-
-It will then call IMFS_memfile_read() with the ``jnode``, file position index,
-buffer and transfer count as arguments.
-
-IMFS_memfile_read() will do the following:
-
-- Verify that the ``jnode`` is associated with a memory file
-
-- Verify that the destination of the read is valid
-
-- Adjust the length of the read if it is too long
-
-- Acquire data from the memory blocks associated with the file
-
-- Update the access time for the data in the file
-
-.. COMMENT: @page
-
-memfile_write() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-memfile_ioctl() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- unsigned32 command,
- void \*buffer
-
-**File:**
-
-memfile.c
-
-**Description:**
-
-The current code is a placeholder for future development. The routine returns
-a successful completion status.
-
-.. COMMENT: @page
-
-memfile_lseek() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-Memfile_lseek()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- off_t offset,
- int whence
-
-**File:**
-
-memfile.c
-
-**Description:**
-
-This routine make sure that the memory based file is sufficiently large to
-allow for the new file position index.
-
-The IMFS_memfile_extend() function is used to evaluate the current size of
-the memory file and allocate additional memory blocks if required by the new
-file position index. A success code is always returned from this routine.
-
-.. COMMENT: @page
-
-IMFS_stat() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_stat()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*loc,
- struct stat \*buf
-
-**File:**
-
-imfs_stat.c
-
-**Description:**
-
-This routine actually performs status processing for both devices and regular
-files.
-
-The IMFS_jnode_t structure is referenced to determine the type of node under
-the filesystem.
-
-If the node is associated with a device, node information is extracted and
-transformed to set the st_dev element of the stat structure.
-
-If the node is a regular file, the size of the regular file is extracted from
-the node.
-
-This routine rejects other node types.
-
-The following information is extracted from the node and placed in the stat
-structure:
-
-- st_mode
-
-- st_nlink
-
-- st_ino
-
-- st_uid
-
-- st_gid
-
-- st_atime
-
-- st_mtime
-
-- st_ctime
-
-.. COMMENT: @page
-
-IMFS_fchmod() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_fchmod()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop
- mode_t mode
-
-**File:**
-
-imfs_fchmod.c
-
-**Description:**
-
-This routine will obtain the pointer to the IMFS_jnode_t structure from the
-information currently in the file control block.
-
-Based on configuration the routine will acquire the user ID from a call to
-getuid() or from the IMFS_jnode_t structure.
-
-It then checks to see if we have the ownership rights to alter the mode of
-the file. If the caller does not, an error code is returned.
-
-An additional test is performed to verify that the caller is not trying to
-alter the nature of the node. If the caller is attempting to alter more than
-the permissions associated with user group and other, an error is returned.
-
-If all the preconditions are met, the user, group and other fields are set
-based on the mode calling parameter.
-
-.. COMMENT: @page
-
-memfile_ftruncate() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-No pathconf() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-NULL
-
-**Arguments:**
-
-Not Implemented
-
-**File:**
-
-Not Implemented
-
-**Description:**
-
-Not Implemented
-
-.. COMMENT: @page
-
-No fsync() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-IMFS_fdatasync() for Regular Files
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-Directory Handler Table Functions
----------------------------------
-
-Handler table functions are defined in a rtems_filesystem_file_handlers_r
-structure. It defines functions that are specific to a node type in a given
-filesystem. One table exists for each of the filesystem’s node types. The
-structure definition appears below. It is followed by general developmental
-information on each of the functions associated with directories contained in
-this function management structure.
-.. code:: c
-
- rtems_filesystem_file_handlers_r IMFS_directory_handlers = {
- IMFS_dir_open,
- IMFS_dir_close,
- IMFS_dir_read,
- NULL, /* write \*/
- NULL, /* ioctl \*/
- IMFS_dir_lseek,
- IMFS_dir_fstat,
- IMFS_fchmod,
- NULL, /* ftruncate \*/
- NULL, /* fpathconf \*/
- NULL, /* fsync \*/
- IMFS_fdatasync,
- IMFS_fcntl
- };
-
-.. COMMENT: @page
-
-IMFS_dir_open() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-imfs_dir_open()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- const char \*pathname,
- unsigned32 flag,
- unsigned32 mode
-
-**File:**
-
-imfs_directory.c
-
-**Description:**
-
-This routine will look into the file control block to find the ``jnode`` that
-is associated with the directory.
-
-The routine will verify that the node is a directory. If its not a directory
-an error code will be returned.
-
-If it is a directory, the offset in the file control block will be set to 0.
-This allows us to start reading at the beginning of the directory.
-
-.. COMMENT: @page
-
-IMFS_dir_close() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-imfs_dir_close()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop
-
-**File:**
-
-imfs_directory.c
-
-**Description:**
-
-This routine is a dummy for directories under the base filesystem. It
-immediately returns a success status.
-
-.. COMMENT: @page
-
-IMFS_dir_read() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-imfs_dir_read
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- void \*buffer,
- unsigned32 count
-
-**File:**
-
-imfs_directory.c
-
-**Description:**
-
-This routine will read a fixed number of directory entries from the current
-directory offset. The number of directory bytes read will be returned from
-this routine.
-
-.. COMMENT: @page
-
-No write() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-No ioctl() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-ioctl
-
-**Arguments:**
-
-**File:**
-
-Not supported
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-IMFS_dir_lseek() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-imfs_dir_lseek()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- off_t offset,
- int whence
-
-**File:**
-
-imfs_directory.c
-
-**Description:**
-
-This routine alters the offset in the file control block.
-
-No test is performed on the number of children under the current open
-directory. The imfs_dir_read() function protects against reads beyond the
-current size to the directory by returning a 0 bytes transfered to the
-calling programs whenever the file position index exceeds the last entry in
-the open directory.
-
-.. COMMENT: @page
-
-IMFS_dir_fstat() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-imfs_dir_fstat()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*loc,
- struct stat \*buf
-
-**File:**
-
-imfs_directory.c
-
-**Description:**
-
-The node access information in the rtems_filesystem_location_info_t structure
-is used to locate the appropriate IMFS_jnode_t structure. The following
-information is taken from the IMFS_jnode_t structure and placed in the stat
-structure:
-
-- st_ino
-
-- st_mode
-
-- st_nlink
-
-- st_uid
-
-- st_gid
-
-- st_atime
-
-- st_mtime
-
-- st_ctime
-
-The st_size field is obtained by running through the chain of directory
-entries and summing the sizes of the dirent structures associated with each
-of the children of the directory.
-
-.. COMMENT: @page
-
-IMFS_fchmod() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_fchmod()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop
- mode_t mode
-
-**File:**
-
-imfs_fchmod.c
-
-**Description:**
-
-This routine will obtain the pointer to the IMFS_jnode_t structure from the
-information currently in the file control block.
-
-Based on configuration the routine will acquire the user ID from a call to
-getuid() or from the IMFS_jnode_t structure.
-
-It then checks to see if we have the ownership rights to alter the mode of
-the file. If the caller does not, an error code is returned.
-
-An additional test is performed to verify that the caller is not trying to
-alter the nature of the node. If the caller is attempting to alter more than
-the permissions associated with user group and other, an error is returned.
-
-If all the preconditions are met, the user, group and other fields are set
-based on the mode calling parameter.
-
-.. COMMENT: @page
-
-No ftruncate() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-No fpathconf() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-fpathconf
-
-**Arguments:**
-
-Not Implemented
-
-**File:**
-
-Not Implemented
-
-**Description:**
-
-Not Implemented
-
-.. COMMENT: @page
-
-No fsync() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-IMFS_fdatasync() for Directories
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-Device Handler Table Functions
-------------------------------
-
-Handler table functions are defined in a rtems_filesystem_file_handlers_r
-structure. It defines functions that are specific to a node type in a given
-filesystem. One table exists for each of the filesystem’s node types. The
-structure definition appears below. It is followed by general developmental
-information on each of the functions associated with devices contained in
-this function management structure.
-.. code:: c
-
- typedef struct {
- rtems_filesystem_open_t open;
- rtems_filesystem_close_t close;
- rtems_filesystem_read_t read;
- rtems_filesystem_write_t write;
- rtems_filesystem_ioctl_t ioctl;
- rtems_filesystem_lseek_t lseek;
- rtems_filesystem_fstat_t fstat;
- rtems_filesystem_fchmod_t fchmod;
- rtems_filesystem_ftruncate_t ftruncate;
- rtems_filesystem_fpathconf_t fpathconf;
- rtems_filesystem_fsync_t fsync;
- rtems_filesystem_fdatasync_t fdatasync;
- } rtems_filesystem_file_handlers_r;
-
-.. COMMENT: @page
-
-device_open() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-device_open()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- const char \*pathname,
- unsigned32 flag,
- unsigned32 mode
-
-**File:**
-
-deviceio.c
-
-**Description:**
-
-This routine will use the file control block to locate the node structure for
-the device.
-
-It will extract the major and minor device numbers from the ``jnode``.
-
-The major and minor device numbers will be used to make a rtems_io_open()
-function call to open the device driver. An argument list is sent to the
-driver that contains the file control block, flags and mode information.
-
-.. COMMENT: @page
-
-device_close() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-device_close()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop
-
-**File:**
-
-deviceio.c
-
-**Description:**
-
-This routine extracts the major and minor device driver numbers from the
-IMFS_jnode_t that is referenced in the file control block.
-
-It also forms an argument list that contains the file control block.
-
-A rtems_io_close() function call is made to close the device specified by the
-major and minor device numbers.
-
-.. COMMENT: @page
-
-device_read() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-device_read()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- void \*buffer,
- unsigned32 count
-
-**File:**
-
-deviceio.c
-
-**Description:**
-
-This routine will extract the major and minor numbers for the device from the -
-jnode- associated with the file descriptor.
-
-A rtems_io_read() call will be made to the device driver associated with the file
-descriptor. The major and minor device number will be sent as arguments as well
-as an argument list consisting of:
-
-- file control block
-
-- file position index
-
-- buffer pointer where the data read is to be placed
-
-- count indicating the number of bytes that the program wishes to read
- from the device
-
-- flags from the file control block
-
-On return from the rtems_io_read() the number of bytes that were actually
-read will be returned to the calling program.
-
-.. COMMENT: @page
-
-device_write() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-device_ioctl() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-ioctl
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- unsigned32 command,
- void \*buffer
-
-**File:**
-
-deviceio.c
-
-**Description:**
-
-This handler will obtain status information about a device.
-
-The form of status is device dependent.
-
-The rtems_io_control() function uses the major and minor number of the device
-to obtain the status information.
-
-rtems_io_control() requires an rtems_libio_ioctl_args_t argument list which
-contains the file control block, device specific command and a buffer pointer
-to return the device status information.
-
-The device specific command should indicate the nature of the information
-that is desired from the device.
-
-After the rtems_io_control() is processed, the buffer should contain the
-requested device information.
-
-If the device information is not obtained properly a -1 will be returned to
-the calling program, otherwise the ioctl_return value is returned.
-
-.. COMMENT: @page
-
-device_lseek() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-device_lseek()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop,
- off_t offset,
- int whence
-
-**File:**
-
-deviceio.c
-
-**Description:**
-
-At the present time this is a placeholder function. It always returns a
-successful status.
-
-.. COMMENT: @page
-
-IMFS_stat() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_stat()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_filesystem_location_info_t \*loc,
- struct stat \*buf
-
-**File:**
-
-imfs_stat.c
-
-**Description:**
-
-This routine actually performs status processing for both devices and regular files.
-
-The IMFS_jnode_t structure is referenced to determine the type of node under the
-filesystem.
-
-If the node is associated with a device, node information is extracted and
-transformed to set the st_dev element of the stat structure.
-
-If the node is a regular file, the size of the regular file is extracted from the node.
-
-This routine rejects other node types.
-
-The following information is extracted from the node and placed in the stat
-structure:
-
-- st_mode
-
-- st_nlink
-
-- st_ino
-
-- st_uid
-
-- st_gid
-
-- st_atime
-
-- st_mtime
-
-- st_ctime
-
-.. COMMENT: @page
-
-IMFS_fchmod() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-IMFS_fchmod()
-
-**Arguments:**
-
-.. code:: c
-
- rtems_libio_t \*iop
- mode_t mode
-
-**File:**
-
-imfs_fchmod.c
-
-**Description:**
-
-This routine will obtain the pointer to the IMFS_jnode_t structure from the
-information currently in the file control block.
-
-Based on configuration the routine will acquire the user ID from a call to
-getuid() or from the IMFS_jnode_t structure.
-
-It then checks to see if we have the ownership rights to alter the mode of
-the file. If the caller does not, an error code is returned.
-
-An additional test is performed to verify that the caller is not trying to
-alter the nature of the node. If the caller is attempting to alter more than
-the permissions associated with user group and other, an error is returned.
-
-If all the preconditions are met, the user, group and other fields are set
-based on the mode calling parameter.
-
-.. COMMENT: @page
-
-No ftruncate() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-No fpathconf() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-fpathconf
-
-**Arguments:**
-
-Not Implemented
-
-**File:**
-
-Not Implemented
-
-**Description:**
-
-Not Implemented
-
-.. COMMENT: @page
-
-No fsync() for Devices
-~~~~~~~~~~~~~~~~~~~~~~
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: @page
-
-No fdatasync() for Devices
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Not Implemented
-
-**Corresponding Structure Element:**
-
-XXX
-
-**Arguments:**
-
-XXX
-
-**File:**
-
-XXX
-
-**Description:**
-
-XXX
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-Miniature In-Memory Filesystem
-##############################
-
-This chapter describes the Miniature In-Memory FileSystem (miniIMFS).
-The miniIMFS is a reduced feature version of the IMFS designed to
-provide minimal functionality and have a low memory footprint.
-
-This chapter should be written after the IMFS chapter is completed
-and describe the implementation of the mini-IMFS.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-Trivial FTP Client Filesystem
-#############################
-
-This chapter describes the Trivial FTP (TFTP) Client Filesystem.
-
-This chapter should be written after the IMFS chapter is completed
-and describe the implementation of the TFTP.
-
-Command and Variable Index
-##########################
-
-There are currently no Command and Variable Index entries.
-
-.. COMMENT: @printindex fn
-
-Concept Index
-#############
-
-There are currently no Concept Index entries.
-
-.. COMMENT: @printindex cp