summaryrefslogtreecommitdiffstats
path: root/doc/filesystem/imfs.t
diff options
context:
space:
mode:
Diffstat (limited to 'doc/filesystem/imfs.t')
-rw-r--r--doc/filesystem/imfs.t2038
1 files changed, 2038 insertions, 0 deletions
diff --git a/doc/filesystem/imfs.t b/doc/filesystem/imfs.t
new file mode 100644
index 0000000000..c6dd6d2535
--- /dev/null
+++ b/doc/filesystem/imfs.t
@@ -0,0 +1,2038 @@
+@c COPYRIGHT (c) 1988-2002.
+@c On-Line Applications Research Corporation (OAR).
+@c All rights reserved.
+@c
+@c $Id$
+@c
+
+@chapter 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.
+
+@section IMFS Per Node Data Structure
+
+Each regular file, device, hard link, and directory is represented by a data
+structure called a @code{jnode}. The @code{jnode} is formally represented by the
+structure:
+
+@example
+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;
+@};
+@end example
+
+The key elements of this structure are listed below together with a brief
+explanation of their role in the filesystem.
+
+@table @b
+
+@item Node
+exists to allow the entire @code{jnode} structure to be included in a chain.
+
+@item Parent
+is a pointer to another @code{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.
+
+@item name
+is the name of this node within the filesystem hierarchical tree. Example: If
+the fully qualified pathname to the @code{jnode} was @code{/a/b/c}, the
+@code{jnode} name field would contain the null terminated string @code{"c"}.
+
+@item st_mode
+is the standard Unix access permissions for the file or directory.
+
+@item st_nlink
+is the number of hard links to this file. When a @code{jnode} is first created
+its link count is set to 1. A @code{jnode} and its associated resources
+cannot be deleted unless its link count is less than 1.
+
+@item st_ino
+is a unique node identification number
+
+@item st_uid
+is the user ID of the file's owner
+
+@item st_gid
+is the group ID of the file's owner
+
+@item st_atime
+is the time of the last access to this file
+
+@item st_mtime
+is the time of the last modification of this file
+
+@item st_ctime
+is the time of the last status change to the file
+
+@item type
+is the indication of node type must be one of the following states:
+
+@itemize @bullet
+@item IMFS_DIRECTORY
+@item IMFS_MEMORY_FILE
+@item IMFS_HARD_LINK
+@item IMFS_SYM_LINK
+@item IMFS_DEVICE
+@end itemize
+
+
+@item info
+is this contains a structure that is unique to file type (See IMFS_typs_union
+in imfs.h).
+
+@itemize @bullet
+
+@item IMFS_DIRECTORY
+
+An IMFS directory contains a dynamic chain structure that
+records all files and directories that are subordinate to the directory node.
+
+@item 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.
+
+@item 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.
+
+@item 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.
+
+@item 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.
+
+@end itemize
+
+@end table
+
+@section Miscellaneous IMFS Information
+
+@section 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.
+
+@subsection Node removal constraints for the IMFS
+
+The IMFS conforms to the general filesystem requirements for node
+removal. See @ref{File and Directory Removal Constraints}.
+
+@subsection IMFS General Housekeeping Notes
+
+The following is a list of odd housekeeping notes for the IMFS.
+
+@itemize @bullet
+
+@item 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.
+
+@item 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.
+
+@end itemize
+
+@section IMFS Operation Tables
+
+@subsection 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.
+
+@example
+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
+@};
+@end example
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_evalpath()
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_evalformake()
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_link()
+
+@subheading Corresponding Structure Element:
+
+link
+
+@subheading Arguments:
+
+
+@example
+rtems_filesystem_location_info_t *to_loc, /* IN */
+rtems_filesystem_location_info_t *parent_loc, /* IN */
+const char *token /* IN */
+@end example
+
+@subheading File:
+
+imfs_link.c
+
+@subheading 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:
+
+@itemize @bullet
+
+@item parent that was determined in the link() function in file link.c
+
+@item Type will be set to IMFS_HARD_LINK
+
+@item name will be set to the normalized name
+
+@item mode of the hard-link will be set to the mode of the target node
+
+@end itemize
+
+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.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_unlink()
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_node_type()
+
+@subheading Corresponding Structure Element:
+
+IMFS_node_type()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t *pathloc /* IN */
+@end example
+
+@subheading File:
+
+imfs_ntype.c
+
+@subheading 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:
+
+@itemize @bullet
+
+@item RTEMS_FILESYSTEM_DIRECTORY
+
+@item RTEMS_FILESYSTEM_DEVICE
+
+@item RTEMS_FILESYSTEM_HARD_LINK
+
+@item RTEMS_FILESYSTEM_MEMORY_FILE
+
+@end itemize
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_mknod()
+
+@subheading Corresponding Structure Element:
+
+IMFS_mknod()
+
+@subheading Arguments:
+
+@example
+const char *token, /* IN */
+mode_t mode, /* IN */
+dev_t dev, /* IN */
+rtems_filesystem_location_info_t *pathloc /* IN/OUT */
+@end example
+
+@subheading File:
+
+imfs_mknod.c
+
+@subheading 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 @code{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 @code{jnode} (ENOMEN).
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_rmnod()
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_chown()
+
+@subheading Corresponding Structure Element:
+
+IMFS_chown()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t *pathloc /* IN */
+uid_t owner /* IN */
+gid_t group /* IN */
+@end example
+
+@subheading File:
+
+imfs_chown.c
+
+@subheading 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.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_freenod()
+
+@subheading Corresponding Structure Element:
+
+IMFS_freenod()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t *pathloc /* IN */
+@end example
+
+@subheading File:
+
+imfs_free.c
+
+@subheading 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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_freenodinfo()
+
+@subheading Corresponding Structure Element:
+
+IMFS_freenodinfo()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t *pathloc /* IN */
+@end example
+
+@subheading File:
+
+imfs_free.c
+
+@subheading Description:
+
+The In-Memory File System does not need to allocate memory during the
+evaluate routines. Therefore, this routine simply routines PASS.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_mount()
+
+@subheading Corresponding Structure Element:
+
+IMFS_mount()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_mount_table_entry_t *mt_entry
+@end example
+
+@subheading File:
+
+imfs_mount.c
+
+@subheading 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.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_fsmount_me()
+
+@subheading Corresponding Structure Element:
+
+IMFS_initialize()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_mount_table_entry_t *mt_entry
+@end example
+
+@subheading File:
+
+imfs_init.c
+
+@subheading 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:
+
+@itemize @bullet
+
+@item link_max
+
+@item max_canon
+
+@item max_input
+
+@item name_max
+
+@item path_max
+
+@item pipe_buf
+
+@item posix_async_io
+
+@item posix_chown_restrictions
+
+@item posix_no_trunc
+
+@item posix_prio_io
+
+@item posix_sync_io
+
+@item posix_vdisable
+
+@end itemize
+
+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:
+
+@itemize @bullet
+
+@item pointer to the allocated root node of the filesystem
+
+@item directory handlers for a directory node under the IMFS filesystem
+
+@item OPS table functions for the IMFS
+
+@end itemize
+
+A 0 will be returned to the calling routine if the process succeeded,
+otherwise a 1 will be returned.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_unmount()
+
+@subheading Corresponding Structure Element:
+
+IMFS_unmount()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_mount_table_entry_t *mt_entry
+@end example
+
+@subheading File:
+
+imfs_unmount.c
+
+@subheading 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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_fsunmount()
+
+@subheading Corresponding Structure Element:
+
+imfs_fsunmount()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_mount_table_entry_t *mt_entry
+@end example
+
+@subheading File:
+
+imfs_init.c
+
+@subheading 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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_utime()
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_eval_link()
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+@c
+@c
+@c
+@c @page
+@subsection 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.
+
+@example
+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
+@};
+@end example
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection memfile_open() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+memfile_open()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+const char *pathname,
+unsigned32 flag,
+unsigned32 mode
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading Description:
+
+Currently this function is a shell. No meaningful processing is performed and
+a success code is always returned.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection memfile_close() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+memfile_close()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading 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.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection memfile_read() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+memfile_read()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+void *buffer,
+unsigned32 count
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading Description:
+
+This routine will determine the @code{jnode} that is associated with this file.
+
+It will then call IMFS_memfile_read() with the @code{jnode}, file position index,
+buffer and transfer count as arguments.
+
+IMFS_memfile_read() will do the following:
+
+@itemize @bullet
+
+@item Verify that the @code{jnode} is associated with a memory file
+
+@item Verify that the destination of the read is valid
+
+@item Adjust the length of the read if it is too long
+
+@item Acquire data from the memory blocks associated with the file
+
+@item Update the access time for the data in the file
+
+@end itemize
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection memfile_write() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection memfile_ioctl() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+unsigned32 command,
+void *buffer
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading Description:
+
+The current code is a placeholder for future development. The routine returns
+a successful completion status.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection memfile_lseek() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+Memfile_lseek()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+off_t offset,
+int whence
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading 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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_stat() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+IMFS_stat()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t *loc,
+struct stat *buf
+@end example
+
+@subheading File:
+
+imfs_stat.c
+
+@subheading 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:
+
+@itemize @bullet
+
+@item st_mode
+
+@item st_nlink
+
+@item st_ino
+
+@item st_uid
+
+@item st_gid
+
+@item st_atime
+
+@item st_mtime
+
+@item st_ctime
+
+@end itemize
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_fchmod() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+IMFS_fchmod()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop
+mode_t mode
+@end example
+
+@subheading File:
+
+imfs_fchmod.c
+
+@subheading 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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection memfile_ftruncate() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+
+@subsubsection No pathconf() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+NULL
+
+@subheading Arguments:
+
+Not Implemented
+
+@subheading File:
+
+Not Implemented
+
+@subheading Description:
+
+Not Implemented
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No fsync() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_fdatasync() for Regular Files
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+@c
+@c
+@c
+@c @page
+@subsection 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.
+
+@example
+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
+@};
+@end example
+
+
+@c
+@c
+@c
+@c @page
+@subsubsection IMFS_dir_open() for Directories
+
+@subheading Corresponding Structure Element:
+
+imfs_dir_open()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+const char *pathname,
+unsigned32 flag,
+unsigned32 mode
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading Description:
+
+This routine will look into the file control block to find the @code{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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_dir_close() for Directories
+
+@subheading Corresponding Structure Element:
+
+imfs_dir_close()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading Description:
+
+This routine is a dummy for directories under the base filesystem. It
+immediately returns a success status.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_dir_read() for Directories
+
+@subheading Corresponding Structure Element:
+
+imfs_dir_read
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+void *buffer,
+unsigned32 count
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading 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.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No write() for Directories
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No ioctl() for Directories
+
+@subheading Corresponding Structure Element:
+
+ioctl
+
+@subheading Arguments:
+
+
+@subheading File:
+
+Not supported
+
+@subheading Description:
+
+XXX
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_dir_lseek() for Directories
+
+@subheading Corresponding Structure Element:
+
+imfs_dir_lseek()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+off_t offset,
+int whence
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading 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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_dir_fstat() for Directories
+
+@subheading Corresponding Structure Element:
+
+imfs_dir_fstat()
+
+@subheading Arguments:
+
+
+@example
+rtems_filesystem_location_info_t *loc,
+struct stat *buf
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading 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:
+
+@itemize @bullet
+@item st_ino
+@item st_mode
+@item st_nlink
+@item st_uid
+@item st_gid
+@item st_atime
+@item st_mtime
+@item st_ctime
+@end itemize
+
+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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_fchmod() for Directories
+
+@subheading Corresponding Structure Element:
+
+IMFS_fchmod()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop
+mode_t mode
+@end example
+
+@subheading File:
+
+imfs_fchmod.c
+
+@subheading 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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No ftruncate() for Directories
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No fpathconf() for Directories
+
+@subheading Corresponding Structure Element:
+
+fpathconf
+
+@subheading Arguments:
+
+Not Implemented
+
+@subheading File:
+
+Not Implemented
+
+@subheading Description:
+
+Not Implemented
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No fsync() for Directories
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_fdatasync() for Directories
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+@c
+@c
+@c
+@c @page
+@subsection 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.
+
+@example
+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;
+@end example
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection device_open() for Devices
+
+@subheading Corresponding Structure Element:
+
+device_open()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+const char *pathname,
+unsigned32 flag,
+unsigned32 mode
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading 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 @code{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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection device_close() for Devices
+
+@subheading Corresponding Structure Element:
+
+device_close()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading 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.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection device_read() for Devices
+
+@subheading Corresponding Structure Element:
+
+device_read()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+void *buffer,
+unsigned32 count
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading 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:
+
+@itemize @bullet
+@item file control block
+
+@item file position index
+
+@item buffer pointer where the data read is to be placed
+
+@item count indicating the number of bytes that the program wishes to read
+from the device
+
+@item flags from the file control block
+
+@end itemize
+
+On return from the rtems_io_read() the number of bytes that were actually
+read will be returned to the calling program.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection device_write() for Devices
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection device_ioctl() for Devices
+
+@subheading Corresponding Structure Element:
+
+ioctl
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+unsigned32 command,
+void *buffer
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading 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.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection device_lseek() for Devices
+
+@subheading Corresponding Structure Element:
+
+device_lseek()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop,
+off_t offset,
+int whence
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading Description:
+
+At the present time this is a placeholder function. It always returns a
+successful status.
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_stat() for Devices
+
+@subheading Corresponding Structure Element:
+
+IMFS_stat()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t *loc,
+struct stat *buf
+@end example
+
+@subheading File:
+
+imfs_stat.c
+
+@subheading 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:
+
+@itemize @bullet
+
+@item st_mode
+
+@item st_nlink
+
+@item st_ino
+
+@item st_uid
+
+@item st_gid
+
+@item st_atime
+
+@item st_mtime
+
+@item st_ctime
+
+@end itemize
+
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection IMFS_fchmod() for Devices
+
+@subheading Corresponding Structure Element:
+
+IMFS_fchmod()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t *iop
+mode_t mode
+@end example
+
+@subheading File:
+
+imfs_fchmod.c
+
+@subheading 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.
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No ftruncate() for Devices
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No fpathconf() for Devices
+
+@subheading Corresponding Structure Element:
+
+fpathconf
+
+@subheading Arguments:
+
+Not Implemented
+
+@subheading File:
+
+Not Implemented
+
+@subheading Description:
+
+Not Implemented
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No fsync() for Devices
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
+
+@c
+@c
+@c
+@c @page
+
+@subsubsection No fdatasync() for Devices
+
+Not Implemented
+
+@subheading Corresponding Structure Element:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Description:
+
+XXX
+
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-05 04:14:38 +0000