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Module Base

module Base: sig .. end
Abstraction of the base of an addressable memory zone, together with the validity of the zone.
type cstring =
| CSString of string
| CSWstring of Escape.wstring (*
This type abstracts over the two kinds of constant strings present in strings. It is used in a few modules below Base.
*) 
type variable_validity = private {
   mutable weak : bool; (*
Indicate that the variable is weak, i.e. that it may represent multiple memory locations
*)
   mutable min_alloc : Abstract_interp.Int.t; (*
First bit guaranteed to be valid; can be -1
*)
   mutable max_alloc : Abstract_interp.Int.t; (*
Last possibly valid bit
*)
   max_allocable : Abstract_interp.Int.t; (*
Maximum valid bit after size increase
*)
}
Validity for variables that might change size.
type base = private
| Var of Cil_types.varinfo * validity (*
Base for a standard C variable.
*)
| CLogic_Var of Cil_types.logic_var * Cil_types.typ * validity (*
Base for a logic variable that has a C type.
*)
| Null (*
Base for an addresse like (int* )0x123
*)
| String of int * cstring (*
contents of the constant string
*)
| Allocated of Cil_types.varinfo * validity (*
Base for a variable dynamically allocated via malloc/calloc/realloc
*) 
type validity =
| Empty (*
For 0-sized bases
*)
| Known of Abstract_interp.Int.t * Abstract_interp.Int.t (*
Valid between those two bits
*)
| Unknown of Abstract_interp.Int.t * Abstract_interp.Int.t option * Abstract_interp.Int.t (*
Unknown(b,k,e) indicates: If k is None, potentially valid between b and e If k is Some k, then b <= k <= e, and the base is
  • valid between b and k;
  • potentially valid between k+1 and e: Accesses on potentially valid parts will succeed, but will also raise an alarm.

*)
| Variable of variable_validity (*
Variable(min_alloc, max_alloc) means:
  • all offsets between 0 and min_alloc are valid; min_alloc can be -1, in which case no offsets are guaranteed to be valid.
  • offsets between min_alloc+1 and max_alloc are potentially valid;
  • offsets above max_alloc+1 are invalid.

*)
| Invalid (*
Valid nowhere. Typically used for the NULL base, or for function pointers.
*) 
module Base: sig .. end
include Datatype.S_with_collections
module Hptset: Hptset.S 
  with type elt = t
  and type 'a shape = 'a Hptmap.Shape(Base).t
module SetLattice: Lattice_type.Lattice_Hashconsed_Set  with module O = Hptset
module Validity: Datatype.S  with type t = validity
val pretty_addr : Format.formatter -> t -> unit
pretty_addr fmt base pretty-prints the name of base on fmt, with a leading ampersand if it is a variable
val typeof : t -> Cil_types.typ option
Type of the memory block that starts from the given base. Useful to give to the function Bit_utils.pretty_bits, typically.

Validity


val pretty_validity : Format.formatter -> validity -> unit
val validity : t -> validity
val validity_from_size : Abstract_interp.Int.t -> validity
validity_from_size size returns Empty if size is zero, or Known (0, size-1) if size > 0. size must not be negative.
Since Aluminium-20160501
val validity_from_type : Cil_types.varinfo -> validity
type range_validity =
| Invalid_range
| Valid_range of Int_Intervals_sig.itv option 
val valid_range : validity -> range_validity
valid_range v returns Invalid_range if v is Invalid, Valid_range None if v is Empty, or Valid_range (Some (mn, mx)) otherwise, where mn and mx are the minimum and maximum (possibly) valid bounds of v.
val is_weak_validity : validity -> bool
is_weak_validity v returns true iff v is a Weak validity.
val create_variable_validity : weak:bool ->
       min_alloc:Abstract_interp.Int.t ->
       max_alloc:Abstract_interp.Int.t -> variable_validity
val update_variable_validity : variable_validity ->
       weak:bool ->
       min_alloc:Abstract_interp.Int.t -> max_alloc:Abstract_interp.Int.t -> unit
Update the corresponding fields of the variable validity. Bases already weak cannot be made 'strong' through this function, and the validity bounds can only grow.

Finding bases


val of_varinfo : Cil_types.varinfo -> t
val of_string_exp : Cil_types.exp -> t
val of_c_logic_var : Cil_types.logic_var -> t
Must only be called on logic variables that have a C type

Origin of the variable underlying a base


exception Not_a_C_variable
val to_varinfo : t -> Cil_types.varinfo
Raises Not_a_C_variable otherwise.
Returns the variable's varinfo if the base corresponds to a C variable (in particular, not a logic variable).
val is_formal_or_local : t -> Cil_types.fundec -> bool
val is_any_formal_or_local : t -> bool
val is_any_local : t -> bool
val is_global : t -> bool
val is_formal_of_prototype : t -> Cil_types.varinfo -> bool
val is_local : t -> Cil_types.fundec -> bool
val is_formal : t -> Cil_types.fundec -> bool
val is_block_local : t -> Cil_types.block -> bool
val is_function : t -> bool

NULL base


val null : t
val is_null : t -> bool
val null_set : Hptset.t
Set containing only the base Base.null.
val min_valid_absolute_address : unit -> Abstract_interp.Int.t
val max_valid_absolute_address : unit -> Abstract_interp.Int.t
Bounds for option absolute-valid-range

Size of a base


val bits_sizeof : t -> Int_Base.t
exception Not_valid_offset
val is_valid_offset : for_writing:bool -> Abstract_interp.Int.t -> t -> Ival.t -> unit
is_valid_offset ~for_writing size b offset checks that offset (expressed in bits) plus size bits is valid in b. It does nothing in this case, and raises Not_valid_offset if the offset may be invalid.

Misc


val is_read_only : t -> bool
Is the base valid as a read/write location, or only for reading. The const attribute is not currently taken into account.
val is_weak : t -> bool
Is the given base a weak one (in the sens that its validity is Weak). Only possible for Allocated bases.
val id : t -> int
val is_aligned_by : t -> Abstract_interp.Int.t -> bool

Registering bases

This is only useful to create an initial memory state for analysis, and is never needed for normal users.
val register_allocated_var : Cil_types.varinfo -> validity -> t
Allocated variables are variables not present in the source of the program, but instead created through dynamic allocation. Their field vsource is set to false.
val register_memory_var : Cil_types.varinfo -> validity -> t
Memory variables are variables not present in the source of the program. They are created only to fill the contents of another variable. Their field vsource is set to false.