@c
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@c
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@c COPYRIGHT (c) 1988-2002.
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@c COPYRIGHT (c) 1988-2002.
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@c On-Line Applications Research Corporation (OAR).
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@c On-Line Applications Research Corporation (OAR).
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@c All rights reserved.
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@c All rights reserved.
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@c
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@c
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@c syscalls.t,v 1.7 2002/01/17 21:47:45 joel Exp
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@c syscalls.t,v 1.7 2002/01/17 21:47:45 joel Exp
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@c
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@c
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@chapter System Call Development Notes
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@chapter System Call Development Notes
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This set of routines represents the application's interface to files and directories
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This set of routines represents the application's interface to files and directories
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under the RTEMS filesystem. All routines are compliant with POSIX standards if a
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under the RTEMS filesystem. All routines are compliant with POSIX standards if a
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specific interface has been established. The list below represents the routines that have
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specific interface has been established. The list below represents the routines that have
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been included as part of the application's interface.
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been included as part of the application's interface.
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@enumerate
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@enumerate
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@item access()
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@item access()
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@item chdir()
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@item chdir()
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@item chmod()
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@item chmod()
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@item chown()
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@item chown()
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@item close()
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@item close()
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@item closedir()
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@item closedir()
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@item dup()
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@item dup()
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@item dup2()
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@item dup2()
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@item fchmod()
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@item fchmod()
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@item fcntl()
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@item fcntl()
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@item fdatasync()
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@item fdatasync()
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@item fpathconf()
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@item fpathconf()
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@item fstat()
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@item fstat()
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@item ioctl()
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@item ioctl()
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@item link()
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@item link()
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@item lseek()
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@item lseek()
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@item mkdir()
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@item mkdir()
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@item mkfifo()
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@item mkfifo()
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@item mknod()
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@item mknod()
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@item mount()
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@item mount()
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@item open()
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@item open()
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@item opendir()
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@item opendir()
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@item pathconf()
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@item pathconf()
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@item read()
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@item read()
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@item readdir()
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@item readdir()
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@item unmount()
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@item unmount()
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@end enumerate
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@end enumerate
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The sections that follow provide developmental information concerning each
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The sections that follow provide developmental information concerning each
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of these functions.
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of these functions.
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@c @page
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@c @page
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@section access
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@section access
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@subheading File:
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@subheading File:
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access.c
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access.c
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@subheading Processing:
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@subheading Processing:
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This routine is layered on the stat() function. It acquires the current
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This routine is layered on the stat() function. It acquires the current
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status information for the specified file and then determines if the
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status information for the specified file and then determines if the
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caller has the ability to access the file for read, write or execute
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caller has the ability to access the file for read, write or execute
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according to the mode argument to this function.
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according to the mode argument to this function.
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@subheading Development Comments:
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@subheading Development Comments:
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This routine is layered on top of the stat() function. As long as the
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This routine is layered on top of the stat() function. As long as the
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st_mode element in the returned structure follow the standard UNIX
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st_mode element in the returned structure follow the standard UNIX
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conventions, this function should support other filesystems without
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conventions, this function should support other filesystems without
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alteration.
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alteration.
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@c @page
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@c @page
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@section chdir
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@section chdir
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@subheading File:
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@subheading File:
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chdir.c
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chdir.c
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@subheading Processing:
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@subheading Processing:
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This routine will determine if the pathname that we are attempting to make
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This routine will determine if the pathname that we are attempting to make
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that current directory exists and is in fact a directory. If these
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that current directory exists and is in fact a directory. If these
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conditions are met the global indication of the current directory
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conditions are met the global indication of the current directory
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(rtems_filesystem_current) is set to the rtems_filesystem_location_info_t
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(rtems_filesystem_current) is set to the rtems_filesystem_location_info_t
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structure that is returned by the rtems_filesystem_evaluate_path()
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structure that is returned by the rtems_filesystem_evaluate_path()
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routine.
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routine.
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@subheading Development Comments:
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@subheading Development Comments:
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This routine is layered on the rtems_filesystem_evaluate_path() routine
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This routine is layered on the rtems_filesystem_evaluate_path() routine
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and the filesystem specific OP table function node_type().
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and the filesystem specific OP table function node_type().
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The routine node_type() must be a routine provided for each filesystem
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The routine node_type() must be a routine provided for each filesystem
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since it must access the filesystems node information to determine which
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since it must access the filesystems node information to determine which
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of the following types the node is:
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of the following types the node is:
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@itemize @bullet
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@itemize @bullet
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@item RTEMS_FILESYSTEM_DIRECTORY
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@item RTEMS_FILESYSTEM_DIRECTORY
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@item RTEMS_FILESYSTEM_DEVICE
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@item RTEMS_FILESYSTEM_DEVICE
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@item RTEMS_FILESYSTEM_HARD_LINK
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@item RTEMS_FILESYSTEM_HARD_LINK
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@item RTEMS_FILESYSTEM_MEMORY_FILE
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@item RTEMS_FILESYSTEM_MEMORY_FILE
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@end itemize
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@end itemize
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This acknowledges that the form of the node management information can
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This acknowledges that the form of the node management information can
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vary from one filesystem implementation to another.
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vary from one filesystem implementation to another.
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RTEMS has a special global structure that maintains the current directory
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RTEMS has a special global structure that maintains the current directory
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location. This global variable is of type rtems_filesystem_location_info_t
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location. This global variable is of type rtems_filesystem_location_info_t
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and is called rtems_filesystem_current. This structure is not always
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and is called rtems_filesystem_current. This structure is not always
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valid. In order to determine if the structure is valid, you must first
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valid. In order to determine if the structure is valid, you must first
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test the node_access element of this structure. If the pointer is NULL,
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test the node_access element of this structure. If the pointer is NULL,
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then the structure does not contain a valid indication of what the current
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then the structure does not contain a valid indication of what the current
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directory is.
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directory is.
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@c @page
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@c @page
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@section chmod
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@section chmod
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@subheading File:
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@subheading File:
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chmod.c
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chmod.c
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@subheading Processing:
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@subheading Processing:
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This routine is layered on the open(), fchmod() and close() functions. As
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This routine is layered on the open(), fchmod() and close() functions. As
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long as the standard interpretation of the mode_t value is maintained,
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long as the standard interpretation of the mode_t value is maintained,
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this routine should not need modification to support other filesystems.
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this routine should not need modification to support other filesystems.
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@subheading Development Comments:
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@subheading Development Comments:
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The routine first determines if the selected file can be open with
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The routine first determines if the selected file can be open with
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read/write access. This is required to allow modification of the mode
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read/write access. This is required to allow modification of the mode
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associated with the selected path.
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associated with the selected path.
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The fchmod() function is used to actually change the mode of the path
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The fchmod() function is used to actually change the mode of the path
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using the integer file descriptor returned by the open() function.
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using the integer file descriptor returned by the open() function.
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After mode modification, the open file descriptor is closed.
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After mode modification, the open file descriptor is closed.
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@c @page
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@c @page
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@section chown
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@section chown
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@subheading File:
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@subheading File:
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chown.c
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chown.c
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@subheading Processing:
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@subheading Processing:
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This routine is layered on the rtems_filesystem_evaluate_path() and the
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This routine is layered on the rtems_filesystem_evaluate_path() and the
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file system specific chown() routine that is specified in the OPS table
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file system specific chown() routine that is specified in the OPS table
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for the file system.
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for the file system.
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@subheading Development Comments:
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@subheading Development Comments:
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rtems_filesystem_evaluate_path() is used to determine if the path
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rtems_filesystem_evaluate_path() is used to determine if the path
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specified actually exists. If it does a rtems_filesystem_location_info_t
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specified actually exists. If it does a rtems_filesystem_location_info_t
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structure will be obtained that allows the shell function to locate the
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structure will be obtained that allows the shell function to locate the
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OPS table that is to be used for this filesystem.
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OPS table that is to be used for this filesystem.
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It is possible that the chown() function that should be in the OPS table
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It is possible that the chown() function that should be in the OPS table
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is not defined. A test for a non-NULL OPS table chown() entry is performed
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is not defined. A test for a non-NULL OPS table chown() entry is performed
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before the function is called.
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before the function is called.
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If the chown() function is defined in the indicated OPS table, the
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If the chown() function is defined in the indicated OPS table, the
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function is called with the rtems_filesystem_location_info_t structure
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function is called with the rtems_filesystem_location_info_t structure
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returned from the path evaluation routine, the desired owner, and group
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returned from the path evaluation routine, the desired owner, and group
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information.
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information.
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@c @page
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@c @page
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@section close
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@section close
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@subheading File:
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@subheading File:
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close.c
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close.c
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@subheading Processing:
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@subheading Processing:
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This routine will allow for the closing of both network connections and
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This routine will allow for the closing of both network connections and
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file system devices. If the file descriptor is associated with a network
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file system devices. If the file descriptor is associated with a network
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device, the appropriate network function handler will be selected from a
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device, the appropriate network function handler will be selected from a
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table of previously registered network functions (rtems_libio_handlers)
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table of previously registered network functions (rtems_libio_handlers)
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and that function will be invoked.
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and that function will be invoked.
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If the file descriptor refers to an entry in the filesystem, the
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If the file descriptor refers to an entry in the filesystem, the
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appropriate handler will be selected using information that has been
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appropriate handler will be selected using information that has been
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placed in the file control block for the device (rtems_libio_t structure).
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placed in the file control block for the device (rtems_libio_t structure).
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@subheading Development Comments:
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@subheading Development Comments:
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rtems_file_descriptor_type examines some of the upper bits of the file
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rtems_file_descriptor_type examines some of the upper bits of the file
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descriptor index. If it finds that the upper bits are set in the file
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descriptor index. If it finds that the upper bits are set in the file
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descriptor index, the device referenced is a network device.
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descriptor index, the device referenced is a network device.
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Network device handlers are obtained from a special registration table
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Network device handlers are obtained from a special registration table
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(rtems_libio_handlers) that is set up during network initialization. The
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(rtems_libio_handlers) that is set up during network initialization. The
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network handler invoked and the status of the network handler will be
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network handler invoked and the status of the network handler will be
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returned to the calling process.
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returned to the calling process.
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If none of the upper bits are set in the file descriptor index, the file
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If none of the upper bits are set in the file descriptor index, the file
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descriptor refers to an element of the RTEMS filesystem.
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descriptor refers to an element of the RTEMS filesystem.
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The following sequence will be performed for any filesystem file
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The following sequence will be performed for any filesystem file
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descriptor:
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descriptor:
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@enumerate
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@enumerate
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@item Use the rtems_libio_iop() function to obtain the rtems_libio_t
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@item Use the rtems_libio_iop() function to obtain the rtems_libio_t
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structure for the file descriptor
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structure for the file descriptor
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@item Range check the file descriptor using rtems_libio_check_fd()
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@item Range check the file descriptor using rtems_libio_check_fd()
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@item Determine if there is actually a function in the selected handler
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@item Determine if there is actually a function in the selected handler
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table that processes the close() operation for the filesystem and node
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table that processes the close() operation for the filesystem and node
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type selected. This is generally done to avoid execution attempts on
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type selected. This is generally done to avoid execution attempts on
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functions that have not been implemented.
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functions that have not been implemented.
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@item If the function has been defined it is invoked with the file control
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@item If the function has been defined it is invoked with the file control
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block pointer as its argument.
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block pointer as its argument.
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@item The file control block that was associated with the open file
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@item The file control block that was associated with the open file
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descriptor is marked as free using rtems_libio_free().
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descriptor is marked as free using rtems_libio_free().
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@item The return code from the close handler is then passed back to the
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@item The return code from the close handler is then passed back to the
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calling program.
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calling program.
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@end enumerate
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@end enumerate
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@c @page
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@c @page
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@section closedir
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@section closedir
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@subheading File:
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@subheading File:
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closedir.c
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closedir.c
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@subheading Processing:
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@subheading Processing:
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The code was obtained from the BSD group. This routine must clean up the
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The code was obtained from the BSD group. This routine must clean up the
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memory resources that are required to track an open directory. The code is
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memory resources that are required to track an open directory. The code is
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layered on the close() function and standard memory free() functions. It
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layered on the close() function and standard memory free() functions. It
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should not require alterations to support other filesystems.
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should not require alterations to support other filesystems.
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@subheading Development Comments:
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@subheading Development Comments:
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The routine alters the file descriptor and the index into the DIR
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The routine alters the file descriptor and the index into the DIR
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structure to make it an invalid file descriptor. Apparently the memory
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structure to make it an invalid file descriptor. Apparently the memory
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that is about to be freed may still be referenced before it is
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that is about to be freed may still be referenced before it is
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reallocated.
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reallocated.
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The dd_buf structure's memory is reallocated before the control structure
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The dd_buf structure's memory is reallocated before the control structure
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that contains the pointer to the dd_buf region.
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that contains the pointer to the dd_buf region.
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DIR control memory is reallocated.
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DIR control memory is reallocated.
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The close() function is used to free the file descriptor index.
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The close() function is used to free the file descriptor index.
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@c @page
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@c @page
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@section dup() Unimplemented
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@section dup() Unimplemented
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@subheading File:
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@subheading File:
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dup.c
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dup.c
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@subheading Processing:
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@subheading Processing:
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@subheading Development Comments:
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@subheading Development Comments:
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@c @page
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@c @page
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@section dup2() Unimplemented
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@section dup2() Unimplemented
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@subheading File:
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@subheading File:
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dup2.c
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dup2.c
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@subheading Processing:
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@subheading Processing:
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@subheading Development Comments:
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@subheading Development Comments:
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@c @page
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@c @page
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@section fchmod
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@section fchmod
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@subheading File:
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@subheading File:
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fchmod.c
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fchmod.c
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@subheading Processing:
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@subheading Processing:
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This routine will alter the permissions of a node in a filesystem. It is
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This routine will alter the permissions of a node in a filesystem. It is
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layered on the following functions and macros:
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layered on the following functions and macros:
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@itemize @bullet
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@itemize @bullet
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@item rtems_file_descriptor_type()
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@item rtems_file_descriptor_type()
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@item rtems_libio_iop()
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@item rtems_libio_iop()
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@item rtems_libio_check_fd()
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@item rtems_libio_check_fd()
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@item rtems_libio_check_permissions()
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@item rtems_libio_check_permissions()
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@item fchmod() function that is referenced by the handler table in the
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@item fchmod() function that is referenced by the handler table in the
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file control block associated with this file descriptor
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file control block associated with this file descriptor
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@end itemize
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@end itemize
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@subheading Development Comments:
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@subheading Development Comments:
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The routine will test to see if the file descriptor index is associated
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The routine will test to see if the file descriptor index is associated
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with a network connection. If it is, an error is returned from this
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with a network connection. If it is, an error is returned from this
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routine.
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routine.
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The file descriptor index is used to obtain the associated file control
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The file descriptor index is used to obtain the associated file control
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block.
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block.
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The file descriptor value is range checked.
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The file descriptor value is range checked.
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The file control block is examined to determine if it has write
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The file control block is examined to determine if it has write
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permissions to allow us to alter the mode of the file.
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permissions to allow us to alter the mode of the file.
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A test is made to determine if the handler table that is referenced in the
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A test is made to determine if the handler table that is referenced in the
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file control block contains an entry for the fchmod() handler function. If
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file control block contains an entry for the fchmod() handler function. If
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it does not, an error is returned to the calling routine.
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it does not, an error is returned to the calling routine.
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If the fchmod() handler function exists, it is called with the file
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If the fchmod() handler function exists, it is called with the file
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control block and the desired mode as parameters.
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control block and the desired mode as parameters.
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@c @page
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@c @page
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@section fcntl()
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@section fcntl()
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@subheading File:
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@subheading File:
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fcntl.c
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fcntl.c
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@subheading Processing:
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@subheading Processing:
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This routine currently only interacts with the file control block. If the
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This routine currently only interacts with the file control block. If the
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structure of the file control block and the associated meanings do not
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structure of the file control block and the associated meanings do not
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change, the partial implementation of fcntl() should remain unaltered for
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change, the partial implementation of fcntl() should remain unaltered for
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other filesystem implementations.
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other filesystem implementations.
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@subheading Development Comments:
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@subheading Development Comments:
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The only commands that have been implemented are the F_GETFD and F_SETFD.
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The only commands that have been implemented are the F_GETFD and F_SETFD.
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The commands manipulate the LIBIO_FLAGS_CLOSE_ON_EXEC bit in the
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The commands manipulate the LIBIO_FLAGS_CLOSE_ON_EXEC bit in the
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@code{flags} element of the file control block associated with the file
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@code{flags} element of the file control block associated with the file
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descriptor index.
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descriptor index.
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The current implementation of the function performs the sequence of
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The current implementation of the function performs the sequence of
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operations below:
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operations below:
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@enumerate
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@enumerate
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|
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@item Test to see if we are trying to operate on a file descriptor
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@item Test to see if we are trying to operate on a file descriptor
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associated with a network connection
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associated with a network connection
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@item Obtain the file control block that is associated with the file
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@item Obtain the file control block that is associated with the file
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descriptor index
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descriptor index
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@item Perform a range check on the file descriptor index.
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@item Perform a range check on the file descriptor index.
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@end enumerate
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@end enumerate
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@c @page
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@c @page
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@section fdatasync
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@section fdatasync
|
|
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@subheading File:
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@subheading File:
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|
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fdatasync.c
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fdatasync.c
|
|
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@subheading Processing:
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@subheading Processing:
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|
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This routine is a template in the in memory filesystem that will route us to the
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This routine is a template in the in memory filesystem that will route us to the
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appropriate handler function to carry out the fdatasync() processing. In the in
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appropriate handler function to carry out the fdatasync() processing. In the in
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memory filesystem this function is not necessary. Its function in a disk based file
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memory filesystem this function is not necessary. Its function in a disk based file
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system that employs a memory cache is to flush all memory based data buffers to
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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:
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disk. It is layered on the following functions and macros:
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@itemize @bullet
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@itemize @bullet
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|
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@item rtems_file_descriptor_type()
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@item rtems_file_descriptor_type()
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|
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@item rtems_libio_iop()
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@item rtems_libio_iop()
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@item rtems_libio_check_fd()
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@item rtems_libio_check_fd()
|
|
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@item rtems_libio_check_permissions()
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@item rtems_libio_check_permissions()
|
|
|
@item fdatasync() function that is referenced by the handler table in the
|
@item fdatasync() function that is referenced by the handler table in the
|
file control block associated with this file descriptor
|
file control block associated with this file descriptor
|
|
|
@end itemize
|
@end itemize
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
The routine will test to see if the file descriptor index is associated
|
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
|
with a network connection. If it is, an error is returned from this
|
routine.
|
routine.
|
|
|
The file descriptor index is used to obtain the associated file control
|
The file descriptor index is used to obtain the associated file control
|
block.
|
block.
|
|
|
The file descriptor value is range checked.
|
The file descriptor value is range checked.
|
|
|
The file control block is examined to determine if it has write
|
The file control block is examined to determine if it has write
|
permissions to the file.
|
permissions to the file.
|
|
|
A test is made to determine if the handler table that is referenced in the
|
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.
|
file control block contains an entry for the fdatasync() handler function.
|
If it does not an error is returned to the calling routine.
|
If it does not an error is returned to the calling routine.
|
|
|
If the fdatasync() handler function exists, it is called with the file
|
If the fdatasync() handler function exists, it is called with the file
|
control block as its parameter.
|
control block as its parameter.
|
|
|
@c @page
|
@c @page
|
@section fpathconf
|
@section fpathconf
|
|
|
@subheading File:
|
@subheading File:
|
|
|
fpathconf.c
|
fpathconf.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine is layered on the following functions and macros:
|
This routine is layered on the following functions and macros:
|
|
|
@itemize @bullet
|
@itemize @bullet
|
|
|
@item rtems_file_descriptor_type()
|
@item rtems_file_descriptor_type()
|
|
|
@item rtems_libio_iop()
|
@item rtems_libio_iop()
|
|
|
@item rtems_libio_check_fd()
|
@item rtems_libio_check_fd()
|
|
|
@item rtems_libio_check_permissions()
|
@item rtems_libio_check_permissions()
|
|
|
@end itemize
|
@end itemize
|
|
|
When a filesystem is mounted, a set of constants is specified for the
|
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 are stored with the mount table entry for the
|
filesystem. These constants appear in the POSIX standard and are listed
|
filesystem. These constants appear in the POSIX standard and are listed
|
below.
|
below.
|
|
|
@itemize @bullet
|
@itemize @bullet
|
|
|
@item PCLINKMAX
|
@item PCLINKMAX
|
|
|
@item PCMAXCANON
|
@item PCMAXCANON
|
|
|
@item PCMAXINPUT
|
@item PCMAXINPUT
|
|
|
@item PCNAMEMAX
|
@item PCNAMEMAX
|
|
|
@item PCPATHMAX
|
@item PCPATHMAX
|
|
|
@item PCPIPEBUF
|
@item PCPIPEBUF
|
|
|
@item PCCHOWNRESTRICTED
|
@item PCCHOWNRESTRICTED
|
|
|
@item PCNOTRUNC
|
@item PCNOTRUNC
|
|
|
@item PCVDISABLE
|
@item PCVDISABLE
|
|
|
@item PCASYNCIO
|
@item PCASYNCIO
|
|
|
@item PCPRIOIO
|
@item PCPRIOIO
|
|
|
@item PCSYNCIO
|
@item PCSYNCIO
|
|
|
|
|
@end itemize
|
@end itemize
|
|
|
This routine will find the mount table information associated the file
|
This routine will find the mount table information associated the file
|
control block for the specified file descriptor parameter. The mount table
|
control block for the specified file descriptor parameter. The mount table
|
entry structure contains a set of filesystem specific constants that can
|
entry structure contains a set of filesystem specific constants that can
|
be accessed by individual identifiers.
|
be accessed by individual identifiers.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
The routine will test to see if the file descriptor index is associated
|
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
|
with a network connection. If it is, an error is returned from this
|
routine.
|
routine.
|
|
|
The file descriptor index is used to obtain the associated file control
|
The file descriptor index is used to obtain the associated file control
|
block.
|
block.
|
|
|
The file descriptor value is range checked.
|
The file descriptor value is range checked.
|
|
|
The file control block is examined to determine if it has read permissions
|
The file control block is examined to determine if it has read permissions
|
to the file.
|
to the file.
|
|
|
Pathinfo in the file control block is used to locate the mount table entry
|
Pathinfo in the file control block is used to locate the mount table entry
|
for the filesystem associated with the file descriptor.
|
for the filesystem associated with the file descriptor.
|
|
|
The mount table entry contains the pathconf_limits_and_options element.
|
The mount table entry contains the pathconf_limits_and_options element.
|
This element is a table of constants that is associated with the
|
This element is a table of constants that is associated with the
|
filesystem.
|
filesystem.
|
|
|
The name argument is used to reference the desired constant from the
|
The name argument is used to reference the desired constant from the
|
pathconf_limits_and_options table.
|
pathconf_limits_and_options table.
|
|
|
|
|
@c @page
|
@c @page
|
@section fstat
|
@section fstat
|
|
|
@subheading File:
|
@subheading File:
|
|
|
fstat.c
|
fstat.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine will return information concerning a file or network
|
This routine will return information concerning a file or network
|
connection. If the file descriptor is associated with a network
|
connection. If the file descriptor is associated with a network
|
connection, the current implementation of @code{fstat()} will return a
|
connection, the current implementation of @code{fstat()} will return a
|
mode set to @code{S_IFSOCK}. In a later version, this routine will map the
|
mode set to @code{S_IFSOCK}. In a later version, this routine will map the
|
status of a network connection to an external handler routine.
|
status of a network connection to an external handler routine.
|
|
|
If the file descriptor is associated with a node under a filesystem, the
|
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
|
fstat() routine will map to the fstat() function taken from the node
|
handler table.
|
handler table.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
This routine validates that the struct stat pointer is not NULL so that
|
This routine validates that the struct stat pointer is not NULL so that
|
the return location is valid.
|
the return location is valid.
|
|
|
The struct stat is then initialized to all zeros.
|
The struct stat is then initialized to all zeros.
|
|
|
rtems_file_descriptor_type() is then used to determine if the file
|
rtems_file_descriptor_type() is then used to determine if the file
|
descriptor is associated with a network connection. If it is, network
|
descriptor is associated with a network connection. If it is, network
|
status processing is performed. In the current implementation, the file
|
status processing is performed. In the current implementation, the file
|
descriptor type processing needs to be improved. It currently just drops
|
descriptor type processing needs to be improved. It currently just drops
|
into the normal processing for file system nodes.
|
into the normal processing for file system nodes.
|
|
|
If the file descriptor is associated with a node under a filesystem, the
|
If the file descriptor is associated with a node under a filesystem, the
|
following steps are performed:
|
following steps are performed:
|
|
|
@enumerate
|
@enumerate
|
|
|
@item Obtain the file control block that is associated with the file descriptor
|
@item Obtain the file control block that is associated with the file descriptor
|
index.
|
index.
|
|
|
@item Range check the file descriptor index.
|
@item Range check the file descriptor index.
|
|
|
@item Test to see if there is a non-NULL function pointer in the handler
|
@item 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
|
table for the fstat() function. If there is, invoke the function with the
|
file control block and the pointer to the stat structure.
|
file control block and the pointer to the stat structure.
|
|
|
@end enumerate
|
@end enumerate
|
|
|
@c @page
|
@c @page
|
@section ioctl
|
@section ioctl
|
|
|
@subheading File:
|
@subheading File:
|
|
|
ioctl.c
|
ioctl.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
Not defined in the POSIX 1003.1b standard but commonly supported in most
|
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
|
UNIX and POSIX system. Ioctl() is a catchall for I/O operations. Routine
|
is layered on external network handlers and filesystem specific handlers.
|
is layered on external network handlers and filesystem specific handlers.
|
The development of new filesystems should not alter the basic processing
|
The development of new filesystems should not alter the basic processing
|
performed by this routine.
|
performed by this routine.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
|
|
The file descriptor is examined to determine if it is associated with a
|
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
|
network device. If it is processing is mapped to an external network
|
handler. The value returned by this handler is then returned to the
|
handler. The value returned by this handler is then returned to the
|
calling program.
|
calling program.
|
|
|
File descriptors that are associated with a filesystem undergo the
|
File descriptors that are associated with a filesystem undergo the
|
following processing:
|
following processing:
|
|
|
@enumerate
|
@enumerate
|
|
|
@item The file descriptor index is used to obtain the associated file
|
@item The file descriptor index is used to obtain the associated file
|
control block.
|
control block.
|
|
|
@item The file descriptor value is range checked.
|
@item The file descriptor value is range checked.
|
|
|
@item A test is made to determine if the handler table that is referenced
|
@item 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
|
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.
|
function. If it does not, an error is returned to the calling routine.
|
|
|
@item If the ioctl() handler function exists, it is called with the file
|
@item If the ioctl() handler function exists, it is called with the file
|
control block, the command and buffer as its parameters.
|
control block, the command and buffer as its parameters.
|
|
|
@item The return code from this function is then sent to the calling
|
@item The return code from this function is then sent to the calling
|
routine.
|
routine.
|
|
|
@end enumerate
|
@end enumerate
|
|
|
|
|
@c @page
|
@c @page
|
@section link
|
@section link
|
|
|
@subheading File:
|
@subheading File:
|
|
|
link.c
|
link.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine will establish a hard link to a file, directory or a device.
|
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
|
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
|
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
|
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
|
links to links are reduced to links to files, directories or devices
|
before they are made.
|
before they are made.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
Calling parameters:
|
Calling parameters:
|
const char *existing
|
const char *existing
|
const char *new
|
const char *new
|
|
|
link() will determine if the target of the link actually exists using
|
link() will determine if the target of the link actually exists using
|
rtems_filesystem_evaluate_path()
|
rtems_filesystem_evaluate_path()
|
|
|
rtems_filesystem_get_start_loc() is used to determine where to start the
|
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
|
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
|
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
|
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
|
of the RTEMS filesystem; otherwise the search will start from the current
|
directory.
|
directory.
|
|
|
The OPS table evalformake() function for the parent's filesystem is used
|
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
|
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
|
locate the start of the new path's name. This name will be used to define
|
a child under the parent directory.
|
a child under the parent directory.
|
|
|
If the parent is found, the routine will determine if the hard link that
|
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
|
we are trying to create will cross a filesystem boundary. This is not
|
permitted for hard-links.
|
permitted for hard-links.
|
|
|
If the hard-link does not cross a filesystem boundary, a check is
|
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()
|
performed to determine if the OPS table contains an entry for the link()
|
function.
|
function.
|
|
|
If a link() function is defined, the OPS table link() function will be
|
If a link() function is defined, the OPS table link() function will be
|
called to establish the actual link within the filesystem.
|
called to establish the actual link within the filesystem.
|
|
|
The return code from the OPS table link() function is returned to the
|
The return code from the OPS table link() function is returned to the
|
calling program.
|
calling program.
|
|
|
@c @page
|
@c @page
|
@section lseek
|
@section lseek
|
|
|
@subheading File:
|
@subheading File:
|
|
|
lseek.c
|
lseek.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine is layered on both external handlers and filesystem / node
|
This routine is layered on both external handlers and filesystem / node
|
type specific handlers. This routine should allow for the support of new
|
type specific handlers. This routine should allow for the support of new
|
filesystems without modification.
|
filesystems without modification.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
This routine will determine if the file descriptor is associated with a
|
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.
|
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
|
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
|
its calling parameters. The return code from the external handler will be
|
returned to the calling routine.
|
returned to the calling routine.
|
|
|
If the file descriptor is not associated with a network connection, it is
|
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
|
associated with a node in a filesystem. The following steps will be
|
performed for filesystem nodes:
|
performed for filesystem nodes:
|
|
|
@enumerate
|
@enumerate
|
|
|
@item The file descriptor is used to obtain the file control block for the
|
@item The file descriptor is used to obtain the file control block for the
|
node.
|
node.
|
|
|
@item The file descriptor is range checked.
|
@item The file descriptor is range checked.
|
|
|
@item The offset element of the file control block is altered as indicated
|
@item The offset element of the file control block is altered as indicated
|
by the offset and whence calling parameters
|
by the offset and whence calling parameters
|
|
|
@item The handler table in the file control block is examined to determine
|
@item 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
|
if it contains an entry for the lseek() function. If it does not an error
|
is returned to the calling program.
|
is returned to the calling program.
|
|
|
@item The lseek() function from the designated handler table is called
|
@item The lseek() function from the designated handler table is called
|
with the file control block, offset and whence as calling arguments
|
with the file control block, offset and whence as calling arguments
|
|
|
@item The return code from the lseek() handler function is returned to the
|
@item The return code from the lseek() handler function is returned to the
|
calling program
|
calling program
|
|
|
@end enumerate
|
@end enumerate
|
|
|
|
|
@c @page
|
@c @page
|
@section mkdir
|
@section mkdir
|
|
|
@subheading File:
|
@subheading File:
|
|
|
mkdir.c
|
mkdir.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine attempts to create a directory node under the filesystem. The
|
This routine attempts to create a directory node under the filesystem. The
|
routine is layered the mknod() function.
|
routine is layered the mknod() function.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
See mknod() for developmental comments.
|
See mknod() for developmental comments.
|
|
|
@c @page
|
@c @page
|
@section mkfifo
|
@section mkfifo
|
|
|
@subheading File:
|
@subheading File:
|
|
|
mkfifo.c
|
mkfifo.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine attempts to create a FIFO node under the filesystem. The
|
This routine attempts to create a FIFO node under the filesystem. The
|
routine is layered the mknod() function.
|
routine is layered the mknod() function.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
See mknod() for developmental comments
|
See mknod() for developmental comments
|
|
|
@c @page
|
@c @page
|
@section mknod
|
@section mknod
|
|
|
@subheading File:
|
@subheading File:
|
|
|
mknod.c
|
mknod.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This function will allow for the creation of the following types of nodes
|
This function will allow for the creation of the following types of nodes
|
under the filesystem:
|
under the filesystem:
|
|
|
@itemize @bullet
|
@itemize @bullet
|
|
|
@item directories
|
@item directories
|
|
|
@item regular files
|
@item regular files
|
|
|
@item character devices
|
@item character devices
|
|
|
@item block devices
|
@item block devices
|
|
|
@item fifos
|
@item fifos
|
|
|
@end itemize
|
@end itemize
|
|
|
At the present time, an attempt to create a FIFO will result in an ENOTSUP
|
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
|
error to the calling function. This routine is layered the filesystem
|
specific routines evalformake and mknod. The introduction of a new
|
specific routines evalformake and mknod. The introduction of a new
|
filesystem must include its own evalformake and mknod function to support
|
filesystem must include its own evalformake and mknod function to support
|
the generic mknod() function. Under this condition the generic mknod()
|
the generic mknod() function. Under this condition the generic mknod()
|
function should accommodate other filesystem types without alteration.
|
function should accommodate other filesystem types without alteration.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
Test for nodal types - I thought that this test should look like the
|
Test for nodal types - I thought that this test should look like the
|
following code:
|
following code:
|
|
|
@example
|
@example
|
if ( (mode & S_IFDIR) = = S_IFDIR) ||
|
if ( (mode & S_IFDIR) = = S_IFDIR) ||
|
(mode & S_IFREG) = = S_IFREG) ||
|
(mode & S_IFREG) = = S_IFREG) ||
|
(mode & S_IFCHR) = = S_IFCHR) ||
|
(mode & S_IFCHR) = = S_IFCHR) ||
|
(mode & S_IFBLK) = = S_IFBLK) ||
|
(mode & S_IFBLK) = = S_IFBLK) ||
|
(mode & S_IFIFO) = = S_IFIFO))
|
(mode & S_IFIFO) = = S_IFIFO))
|
Set_errno_and_return_minus_one (EINVAL);
|
Set_errno_and_return_minus_one (EINVAL);
|
|
|
@end example
|
@end example
|
|
|
Where:
|
Where:
|
|
|
@itemize @bullet
|
@itemize @bullet
|
@item S_IFREG (0100000) - Creation of a regular file
|
@item S_IFREG (0100000) - Creation of a regular file
|
@item S_IFCHR (0020000) - Creation of a character device
|
@item S_IFCHR (0020000) - Creation of a character device
|
@item S_IFBLK (0060000) - Creation of a block device
|
@item S_IFBLK (0060000) - Creation of a block device
|
@item S_IFIFO (0010000) - Creation of a FIFO
|
@item S_IFIFO (0010000) - Creation of a FIFO
|
@end itemize
|
@end itemize
|
|
|
Determine if the pathname that we are trying to create starts at the root
|
Determine if the pathname that we are trying to create starts at the root
|
directory or is relative to the current directory using the
|
directory or is relative to the current directory using the
|
rtems_filesystem_get_start_loc() function.
|
rtems_filesystem_get_start_loc() function.
|
|
|
Determine if the pathname leads to a valid directory that can be accessed
|
Determine if the pathname leads to a valid directory that can be accessed
|
for the creation of a node.
|
for the creation of a node.
|
|
|
If the pathname is a valid location to create a node, verify that a
|
If the pathname is a valid location to create a node, verify that a
|
filesystem specific mknod() function exists.
|
filesystem specific mknod() function exists.
|
|
|
If the mknod() function exists, call the filesystem specific mknod()
|
If the mknod() function exists, call the filesystem specific mknod()
|
function. Pass the name, mode, device type and the location information
|
function. Pass the name, mode, device type and the location information
|
associated with the directory under which the node will be created.
|
associated with the directory under which the node will be created.
|
|
|
@c @page
|
@c @page
|
@section mount
|
@section mount
|
|
|
@subheading File:
|
@subheading File:
|
|
|
mount.c
|
mount.c
|
|
|
|
|
Arguments (Not a standard POSIX call):
|
Arguments (Not a standard POSIX call):
|
|
|
rtems_filesystem_mount_table_entry_t **mt_entry,
|
rtems_filesystem_mount_table_entry_t **mt_entry,
|
|
|
If the mount operation is successful, this pointer to a pointer will be
|
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
|
set to reference the mount table chain entry that has been allocated for
|
this file system mount.
|
this file system mount.
|
|
|
rtems_filesystem_operations_table *fs_ops,
|
rtems_filesystem_operations_table *fs_ops,
|
|
|
This is a pointer to a table of functions that are associated with the
|
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 that we are about to mount. This is the mechanism to selected
|
file system type without keeping a dynamic database of all possible file
|
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
|
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
|
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
|
the RTEMS build. Unused filesystems types will not be drawn into the
|
build.
|
build.
|
|
|
char *fsoptions,
|
char *fsoptions,
|
|
|
This argument points to a string that selects mounting for read only
|
This argument points to a string that selects mounting for read only
|
access or read/write access. Valid states are "RO" and "RW"
|
access or read/write access. Valid states are "RO" and "RW"
|
|
|
char *device,
|
char *device,
|
|
|
This argument is reserved for the name of a device that will be used to
|
This argument is reserved for the name of a device that will be used to
|
access the filesystem information. Current filesystem implementations are
|
access the filesystem information. Current filesystem implementations are
|
memory based and do not require a device to access filesystem information.
|
memory based and do not require a device to access filesystem information.
|
|
|
char *mount_point
|
char *mount_point
|
|
|
This is a pathname to a directory in a currently mounted filesystem that
|
This is a pathname to a directory in a currently mounted filesystem that
|
allows read, write and execute permissions. If successful, the node found
|
allows read, write and execute permissions. If successful, the node found
|
by evaluating this name, is stored in the mt_entry.
|
by evaluating this name, is stored in the mt_entry.
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine will handle the mounting of a filesystem on a mount point. If
|
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
|
the operation is successful, a pointer to the mount table chain entry
|
associated with the mounted filesystem will be returned to the calling
|
associated with the mounted filesystem will be returned to the calling
|
function. The specifics about the processing required at the mount point
|
function. The specifics about the processing required at the mount point
|
and within the filesystem being mounted is isolated in the filesystem
|
and within the filesystem being mounted is isolated in the filesystem
|
specific mount() and fsmount_me() functions. This allows the generic
|
specific mount() and fsmount_me() functions. This allows the generic
|
mount() function to remain unaltered even if new filesystem types are
|
mount() function to remain unaltered even if new filesystem types are
|
introduced.
|
introduced.
|
|
|
|
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
This routine will use get_file_system_options() to determine if the mount
|
This routine will use get_file_system_options() to determine if the mount
|
options are valid ("RO" or "RW").
|
options are valid ("RO" or "RW").
|
|
|
It confirms that a filesystem ops-table has been selected.
|
It confirms that a filesystem ops-table has been selected.
|
|
|
Space is allocated for a mount table entry and selective elements of the
|
Space is allocated for a mount table entry and selective elements of the
|
temporary mount table entry are initialized.
|
temporary mount table entry are initialized.
|
|
|
If a mount point is specified: The mount point is examined to determine
|
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
|
that it is a directory and also has the appropriate permissions to allow a
|
filesystem to be mounted.
|
filesystem to be mounted.
|
|
|
The current mount table chain is searched to determine that there is not
|
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.
|
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
|
If a mount function is defined in the ops table for the filesystem
|
containing the mount point, it is called at this time.
|
containing the mount point, it is called at this time.
|
|
|
If no mount point is specified: Processing if performed to set up the
|
If no mount point is specified: Processing if performed to set up the
|
mount table chain entry as the base filesystem.
|
mount table chain entry as the base filesystem.
|
|
|
If the fsmount_me() function is specified for ops-table of the 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
|
being mounted, that function is called to initialize for the new
|
filesystem.
|
filesystem.
|
|
|
On successful completion, the temporary mount table entry will be placed
|
On successful completion, the temporary mount table entry will be placed
|
on the mount table chain to record the presence of the mounted filesystem.
|
on the mount table chain to record the presence of the mounted filesystem.
|
|
|
@c @page
|
@c @page
|
@section open
|
@section open
|
|
|
@subheading File:
|
@subheading File:
|
|
|
open.c
|
open.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine is layered on both RTEMS calls and filesystem specific
|
This routine is layered on both RTEMS calls and filesystem specific
|
implementations of the open() function. These functional interfaces should
|
implementations of the open() function. These functional interfaces should
|
not change for new filesystems and therefore this code should be stable as
|
not change for new filesystems and therefore this code should be stable as
|
new file systems are introduced.
|
new file systems are introduced.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
This routine will allocate a file control block for the file or device
|
This routine will allocate a file control block for the file or device
|
that we are about to open.
|
that we are about to open.
|
|
|
It will then test to see if the pathname exists. If it does a
|
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
|
rtems_filesystem_location_info_t data structure will be filled out. This
|
structure contains information that associates node information,
|
structure contains information that associates node information,
|
filesystem specific functions and mount table chain information with the
|
filesystem specific functions and mount table chain information with the
|
pathname.
|
pathname.
|
|
|
If the create option has been it will attempt to create a node for a
|
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
|
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
|
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
|
the file under the filesystem that contains the pathname. When a new node
|
is created, it is also evaluated so that an appropriate
|
is created, it is also evaluated so that an appropriate
|
rtems_filesystem_location_info_t data structure can be filled out for the
|
rtems_filesystem_location_info_t data structure can be filled out for the
|
newly created node.
|
newly created node.
|
|
|
If the file exists or the new file was created successfully, the file
|
If the file exists or the new file was created successfully, the file
|
control block structure will be initialized with handler table
|
control block structure will be initialized with handler table
|
information, node information and the rtems_filesystem_location_info_t
|
information, node information and the rtems_filesystem_location_info_t
|
data structure that describes the node and filesystem data in detail.
|
data structure that describes the node and filesystem data in detail.
|
|
|
If an open() function exists in the filesystem specific handlers table for
|
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.
|
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
|
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
|
of freeing the file control block structure that was allocated at the
|
beginning of the generic open() routine.
|
beginning of the generic open() routine.
|
|
|
On a successful open(), the index into the file descriptor table will be
|
On a successful open(), the index into the file descriptor table will be
|
calculated and returned to the calling routine.
|
calculated and returned to the calling routine.
|
|
|
@c @page
|
@c @page
|
@section opendir
|
@section opendir
|
|
|
@subheading File:
|
@subheading File:
|
|
|
opendir.c
|
opendir.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine will attempt to open a directory for read access. It will
|
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
|
setup a DIR control structure that will be used to access directory
|
information. This routine is layered on the generic open() routine and
|
information. This routine is layered on the generic open() routine and
|
filesystem specific directory processing routines.
|
filesystem specific directory processing routines.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
The BSD group provided this routine.
|
The BSD group provided this routine.
|
|
|
@c @page
|
@c @page
|
@section pathconf
|
@section pathconf
|
|
|
@subheading File:
|
@subheading File:
|
|
|
pathconf.c
|
pathconf.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine will obtain the value of one of the path configuration
|
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
|
parameters and return it to the calling routine. It is layered on the
|
generic open() and fpathconf() functions. These interfaces should not
|
generic open() and fpathconf() functions. These interfaces should not
|
change with the addition of new filesystem types.
|
change with the addition of new filesystem types.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
This routine will try to open the file indicated by path.
|
This routine will try to open the file indicated by path.
|
|
|
If successful, the file descriptor will be used to access the pathconf
|
If successful, the file descriptor will be used to access the pathconf
|
value specified by @code{name} using the fpathconf() function.
|
value specified by @code{name} using the fpathconf() function.
|
|
|
The file that was accessed is then closed.
|
The file that was accessed is then closed.
|
|
|
@c @page
|
@c @page
|
@section read
|
@section read
|
|
|
@subheading File:
|
@subheading File:
|
|
|
deviceio.c
|
deviceio.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine is layered on a set of RTEMS calls and filesystem specific
|
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
|
read operations. The functions are layered in such a way as to isolate
|
them from change as new filesystems are introduced.
|
them from change as new filesystems are introduced.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
This routine will examine the type of file descriptor it is sent.
|
This routine will examine the type of file descriptor it is sent.
|
|
|
If the file descriptor is associated with a network device, the read
|
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
|
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
|
the network handler will then be sent as the return code from generic
|
read() function.
|
read() function.
|
|
|
For file descriptors that are associated with the filesystem the following
|
For file descriptors that are associated with the filesystem the following
|
sequence will be performed:
|
sequence will be performed:
|
|
|
@enumerate
|
@enumerate
|
|
|
@item Obtain the file control block associated with the file descriptor
|
@item Obtain the file control block associated with the file descriptor
|
|
|
@item Range check the file descriptor
|
@item Range check the file descriptor
|
|
|
@item Determine that the buffer pointer is not invalid
|
@item Determine that the buffer pointer is not invalid
|
|
|
@item Check that the count is not zero
|
@item Check that the count is not zero
|
|
|
@item Check the file control block to see if we have permissions to read
|
@item Check the file control block to see if we have permissions to read
|
|
|
@item If there is a read function in the handler table, invoke the handler
|
@item If there is a read function in the handler table, invoke the handler
|
table read() function
|
table read() function
|
|
|
@item Use the return code from the handler table read function(number of
|
@item Use the return code from the handler table read function(number of
|
bytes read) to increment the offset element of the file control block
|
bytes read) to increment the offset element of the file control block
|
|
|
@item Return the number of bytes read to the calling program
|
@item Return the number of bytes read to the calling program
|
|
|
@end enumerate
|
@end enumerate
|
|
|
@c @page
|
@c @page
|
@section readdir
|
@section readdir
|
|
|
@subheading File:
|
@subheading File:
|
|
|
readdir.c
|
readdir.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine was acquired from the BSD group. It has not been altered from
|
This routine was acquired from the BSD group. It has not been altered from
|
its original form.
|
its original form.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
The routine calls a customized getdents() function that is provided by the
|
The routine calls a customized getdents() function that is provided by the
|
user. This routine provides the filesystem specific aspects of reading a
|
user. This routine provides the filesystem specific aspects of reading a
|
directory.
|
directory.
|
|
|
It is layered on the read() function in the directory handler table. This
|
It is layered on the read() function in the directory handler table. This
|
function has been mapped to the Imfs_dir_read() function.
|
function has been mapped to the Imfs_dir_read() function.
|
|
|
@c @page
|
@c @page
|
@section unmount
|
@section unmount
|
|
|
@subheading File:
|
@subheading File:
|
|
|
unmount.c
|
unmount.c
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
This routine will attempt to dismount a mounted filesystem and then free
|
This routine will attempt to dismount a mounted filesystem and then free
|
all resources that were allocated for the management of that filesystem.
|
all resources that were allocated for the management of that filesystem.
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
@itemize @bullet
|
@itemize @bullet
|
|
|
@item This routine will determine if there are any filesystems currently
|
@item This routine will determine if there are any filesystems currently
|
mounted under the filesystem that we are trying to dismount. This would
|
mounted under the filesystem that we are trying to dismount. This would
|
prevent the dismount of the filesystem.
|
prevent the dismount of the filesystem.
|
|
|
@item It will test to see if the current directory is in the filesystem
|
@item 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
|
that we are attempting to dismount. This would prevent the dismount of the
|
filesystem.
|
filesystem.
|
|
|
@item It will scan all the currently open file descriptors to determine is
|
@item 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
|
there is an open file descriptor to a file in the filesystem that we are
|
attempting to unmount().
|
attempting to unmount().
|
|
|
@end itemize
|
@end itemize
|
|
|
If the above preconditions are met then the following sequence is
|
If the above preconditions are met then the following sequence is
|
performed:
|
performed:
|
|
|
@enumerate
|
@enumerate
|
|
|
@item Call the filesystem specific unmount() function for the filesystem
|
@item Call the filesystem specific unmount() function for the filesystem
|
that contains the mount point. This routine should indicate that the mount
|
that contains the mount point. This routine should indicate that the mount
|
point no longer has a filesystem mounted below it.
|
point no longer has a filesystem mounted below it.
|
|
|
@item Call the filesystem specific fsunmount_me() function for the mounted
|
@item Call the filesystem specific fsunmount_me() function for the mounted
|
filesystem that we are trying to unmount(). This routine should clean up
|
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
|
any resources that are no longer needed for the management of the file
|
system being un-mounted.
|
system being un-mounted.
|
|
|
@item Extract the mount table entry for the filesystem that was just
|
@item Extract the mount table entry for the filesystem that was just
|
dismounted from the mount table chain.
|
dismounted from the mount table chain.
|
|
|
@item Free the memory associated with the extracted mount table entry.
|
@item Free the memory associated with the extracted mount table entry.
|
|
|
@end enumerate
|
@end enumerate
|
|
|
@c @page
|
@c @page
|
@section eval
|
@section eval
|
|
|
@subheading File:
|
@subheading File:
|
|
|
XXX
|
XXX
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
XXX
|
XXX
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
XXX
|
XXX
|
|
|
@c @page
|
@c @page
|
@section getdentsc
|
@section getdentsc
|
|
|
@subheading File:
|
@subheading File:
|
|
|
XXX
|
XXX
|
|
|
@subheading Processing:
|
@subheading Processing:
|
|
|
XXX
|
XXX
|
|
|
@subheading Development Comments:
|
@subheading Development Comments:
|
|
|
XXX
|
XXX
|
|
|
|
|
