RTEMS 4.9.5 On-Line Library

fpathconf

RTEMS Filesystem Design Guide

4.12: fpathconf

File:

fpathconf.c

Processing:

This routine is layered on the following functions and macros:

rtems_file_descriptor_type()
rtems_libio_iop()
rtems_libio_check_fd()
rtems_libio_check_permissions()

When a filesystem is mounted, a set of constants is specified for the filesystem. These constants are stored with the mount table entry for the filesystem. These constants appear in the POSIX standard and are listed below.

PCLINKMAX
PCMAXCANON
PCMAXINPUT
PCNAMEMAX
PCPATHMAX
PCPIPEBUF
PCCHOWNRESTRICTED
PCNOTRUNC
PCVDISABLE
PCASYNCIO
PCPRIOIO
PCSYNCIO

This routine will find the mount table information associated the file control block for the specified file descriptor parameter. The mount table entry structure contains a set of filesystem specific constants that can be accessed by individual identifiers.

Development Comments:

The routine will test to see if the file descriptor index is associated with a network connection. If it is, an error is returned from this routine.

The file descriptor index is used to obtain the associated file control block.

The file descriptor value is range checked.

The file control block is examined to determine if it has read permissions to the file.

Pathinfo in the file control block is used to locate the mount table entry for the filesystem associated with the file descriptor.

The mount table entry contains the pathconf_limits_and_options element. This element is a table of constants that is associated with the filesystem.

The name argument is used to reference the desired constant from the pathconf_limits_and_options table.

RTEMS Filesystem Design Guide