Description

   The pathconf function allows an application to determine the
   characteristics of operations supported by the file system
   underlying the filenamed by path. Read, write, or execute
   permission of the named file is not required, but you must be
   able to search all directories in the path leading to the file.

   Symbolic values for the name argument are defined in the
   <unistd.h> header file, as follows:

   _PC_LINK_MAX    The maximum number of links to the file. If the
                   path argument refers to a directory, the value
                   returned applies to the directory itself.
   _PC_MAX_CANON   The maximum number of bytes in a canonical
                   input line. This is applicable only to terminal
                   devices.
   _PC_MAX_INPUT   The number of types allowed in an input queue.
                   This is applicable only to terminal devices.
   _PC_NAME_MAX    Maximum number of bytes in a filename (not
                   including a terminating null). The byte range
                   value is between 13 and 255. This is applicable
                   only to a directory file. The value returned
                   applies to filenames within the directory.
   _PC_PATH_MAX    Maximum number of bytes in a pathname (not
                   including a terminating null). The value is never
                   larger than 65,535. This is applicable only to a
                   directory file. The value returned is the maximum
                   length of a relative pathname when the specified
                   directory is the working directory.
   _PC_PIPE_BUF    Maximum number of bytes guaranteed to be written
                   atomically. This is applicable only to a FIFO.
                   The value returned applies to the referenced
                   object. If the path argument refers to a
                   directory, the value returned applies to any
                   FIFO that exists or can be created within the
                   directory.
   _PC_CHOWN_      This is applicable only to a directory file. The
   RESTRICTED      value returned applies to any files (other than
                   directories) that exist or can be created within
                   the directory.
   _PC_NO_TRUNC    Returns 1 if supplying a component name longer
                   than allowed by NAME_MAX causes an error. Returns
                   0 (zero) if long component names are truncated.
                   This is applicable only to a directory file.
   _PC_VDISABLE    This is always 0 (zero); no disabling character
                   is defined. This is applicable only to a terminal
                   device.