Informal Introduction

From the logical point of view directories differ from regular files, however Unix
treates them in the same way. Generic file is used to specify the 'general' file
which may be either directory or regular file.

(0) CHARACTERISTICS

-type specified: genericfile

-features: deterministic, non-parameterized

-foreign types: directory, sequence, byte, global, mystring

(1) SYNTAX

ACCESS-PROGRAMS

(2) CANONICAL TRACES

canonical(T) T = _ ( s:<sequence> [T = CREATESEQ(*, s) ] d:<directory> [T = CREATEDIR(*, d) ])

AUXILIARY FUNCTIONS

interrorval: <int>

interrorval() = -1

errorval: <byte>

errorval() = -1

t_empty: <int>

t_empty() = -1

t_seq: <int>

t_seq() = 0

t_dir: <int>

t_dir() = 1

type: <genericfile> <int>

type(gf) =

Condition	Value
gf = _	t_empty()
s:<sequence> [gf = CREATESEQ(*, s) ]	t_seq()
d:<directory> [gf = CREATEDIR(*, d) ]	t_dir()

getseq: <genericfile> <sequence>

getseq(gf) =

Condition	Value
type(gf) t_seq()	sequence::_
type(gf) = t_seq()	s where s:<sequence> [gf = CREATESEQ(*, s) ]

getdir: <genericfile> <directory>

getdir(gf) =

Condition	Value
type(gf) t_dir()	directory::_
type(gf) = t_dir()	d where d:<directory> [gf = CREATEDIR(*, d) ]

get: <genericfile> × <int> <byte>

get(gf, pos) =

Condition	Value
type(gf) t_seq() (pos < 0 pos global::G_sequence_size())	errorval()
type(gf) = t_seq() (pos 0 pos < global::G_sequence_size())	sequence::get(getseq(gf), pos)

size: <genericfile> <int>

size(gf) =

Condition	Value
type(gf) t_seq()	interrorval()
type(gf) = t_seq()	sequence::size(getseq(gf))

exists: <genericfile> × <mystring> <bool>

exists(gf, name) =

Condition	Value
type(gf) t_dir()	false
type(gf) = t_dir()	directory::exists(getdir(gf), name)

getinodetableindex: <genericfile> × <mystring> <int>

getinodetableindex(gf, name) =

Condition	Value
type(gf) t_dir()	interrorval()
type(gf) = t_dir()	directory::getinodetableindex(getdir(gf), name)

isfull: <genericfile> <bool>

isfull(gf) =

Condition	Value
type(gf) t_dir()	false
type(gf) = t_dir()	directory::isfull(getdir(gf))

(3) SEMANTICS

Legality(CREATESEQ((n, T), s)) =

Condition	Value
type(T) t_seq() type(T) t_empty()	%illegal operation%
type(T) = t_seq() type(T) = t_empty()	%legal%

CREATESEQ((n, T) , s) = CREATESEQ(*, s)

Legality(CREATEDIR((n, T), d)) =

Condition	Value
type(T) t_seq() type(T) t_empty()	%illegal operation%
type(T) = t_seq() type(T) = t_empty()	%legal%

CREATEDIR((n, T) , d) = CREATEDIR(*, d)

Legality(RELEASE((n, T))) = %legal%

RELEASE((n, T) ) = _

Legality(TYPE(T)) = %legal%

TYPE(T) = type(T)

Legality(PUT((n, T), pos, b)) =

Condition	Value
type(T) t_seq() (pos < 0 pos global::G_sequence_size())	%type mismatch or invalid position%
type(T) = t_seq() (pos 0 pos < global::G_sequence_size())	%legal%

PUT((n, T) , pos, b) = CREATESEQ(*, sequence::PUT((*1,getseq(T)) , pos, b))

Legality(GET(T, pos, (n, b))) =

Condition	Value
type(T) t_seq() (pos < 0 pos global::G_sequence_size())	%type mismatch or invalid position%
type(T) = t_seq() (pos 0 pos < global::G_sequence_size())	%legal%

GET(T, pos, (n, b) ) = get(T, pos)

Legality(TRUNC((n, T), pos)) =

Condition	Value
type(T) t_seq() (pos < 0 pos global::G_sequence_size())	%type mismatch or invalid position%
type(T) = t_seq() (pos 0 pos < global::G_sequence_size())	%legal%

TRUNC((n, T) , pos) = CREATESEQ(*, sequence::TRUNC((*1,getseq(T)) , pos))

Legality(SIZE(T)) = %legal%

SIZE(T) = size(T)

Legality(CREATE((n, T), name, v)) =

Condition	Value
type(T) t_dir() (exists(T, name) (¬mystring::iscorrectfilename(name) (v < 0 length(T) = global::G_directory_size() )))	%type mismatch, invalid file name or i-node number%
type(T) = t_dir() ¬(exists(T, name) (mystring::iscorrectfilename(name) (v 0 length(T) < global::G_directory_size())))	%legal%

CREATE((n, T) , name, v) = CREATEDIR(*, directory::CREATE((*1,getdir(T)) , name, v))

Legality(REMOVE((n, T), name)) =

Condition	Value
type(T) t_dir() ¬exists(T, name)	%type mismatch or file doesn't exist%
type(T) = t_dir() exists(T, name)	%legal%

REMOVE((n, T) , name) = CREATEDIR(*, directory::REMOVE((*1,getdir(T)) , name))

Legality(GETINODETABLEINDEX(T, name)) = %legal%

GETINODETABLEINDEX(T, name) = getinodetableindex(T, name)

Legality(EXISTS(T, name)) =

Condition	Value
type(T) t_dir()	%type mismatch%
type(T) = t_dir()	%legal%

EXISTS(T, name) = exists(T, name)

Legality(ISFULL(T)) =

Condition	Value
type(T) t_dir()	%type mismatch%
type(T) = t_dir()	%legal%

ISFULL(T) = isfull(T)