Added information on the evaluate and evaluate for make routines.

Added details on how generic code starts the pathevaluation process.

1 files changed, 80 insertions, 15 deletions

diff --git a/doc/filesystem/patheval.t b/doc/filesystem/patheval.t
index b5108f08fb..de8c1bb01f 100644
--- a/doc/filesystem/patheval.t
+++ b/doc/filesystem/patheval.t
@@ -8,38 +8,103 @@
 
 @chapter Pathname Evaluation
 
+This chapter describes the pathname evaluation process for the 
+RTEMS Filesystem Infrastructure.
+
+@example
 XXX Include graphic of the path evaluation process with Jennifer's
-explanations
+XXX explanations
+@end example
 
-@itemize @bullet
+@section Pathname Evaluation Handlers
 
-@item There are two pathname evaluation routines.  The handler patheval()
+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.
 
-@item Pathname evaluation is specific to a filesystem
+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.  
+
+@section 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.
+
+
+@section The rtems_filesystem_location_info_t Structure
+
+The @code{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 
+@code{rtems_filesystem_root} and the @code{rtems_filesystem_current}.
+Both are initially defined to be the root node of the base filesystem.
+Once the chdir command is correctly used the @code{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 
+@code{rtems_filesystem_root} is used as the node to start the evaluation 
+with.  Otherwise, the @code{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.
+
+@example
+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;
+@};
+@end example
+
+@table @b
+
+@item 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.
+
+@item 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.
 
-@item Mechanics of crossing a mount point during the evaluation of a path
-name
+@item 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.
 
-@item Role of rtems_filesystem_location_info_t structure
+@item mt_entry
+This element identifies the mount table entry for this instance of the
+filesystem.
 
-@itemize @bullet
+@end table
 
-@item Finding filesystem node information
 
-@item Finding filesystem node handlers
 
-@item Finding filesystem node operations table
 
-@item Finding mount table entry for the filesystem that this node is part
-of 
 
-@end itemize
 
-@end itemize