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Data_encoding: catching more invalid encoding

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This commit is contained in:
Raphaël Proust 2018-05-23 13:17:23 +08:00 committed by Benjamin Canou
parent b0be5b630d
commit 00d596e9c2
1 changed files with 69 additions and 2 deletions
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71
src/lib_data_encoding/encoding.ml
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@ -177,10 +177,69 @@ let rec classify : type a. a t -> Kind.t = fun e ->
let make ?json_encoding encoding = { encoding ; json_encoding }
module Fixed = struct
let string n = make @@ String (`Fixed n)
let bytes n = make @@ Bytes (`Fixed n)
let string n =
if n <= 0 then
invalid_arg "Cannot create a string encoding fo negative or null fixed length."
else
make @@ String (`Fixed n)
let bytes n =
if n <= 0 then
invalid_arg "Cannot create a byte encoding fo negative or null fixed length."
else
make @@ Bytes (`Fixed n)
end
let rec is_zeroable: type t. t encoding -> bool = fun e ->
(* Whether an encoding can ever produce zero-byte of encoding. It is dnagerous
to place zero-size elements in a collection (list/array) because
they are indistinguishable from the abscence of elements. *)
match e.encoding with
(* trivially true *)
| Null -> true (* always true *)
| Empty -> true (* always true *)
| Ignore -> true (* always true *)
| Constant _ -> true (* always true *)
(* trivially false *)
| Bool -> false
| Int8 -> false
| Uint8 -> false
| Int16 -> false
| Uint16 -> false
| Int31 -> false
| Int32 -> false
| Int64 -> false
| Z -> false
| RangedInt _ -> false
| RangedFloat _ -> false
| Float -> false
| Bytes _ -> false
| String _ -> false
| String_enum _ -> false
(* true in some cases, but in practice always protected by Dynamic *)
| Array _ -> true (* 0-element array *)
| List _ -> true (* 0-element list *)
(* represented as whatever is inside: truth mostly propagates *)
| Obj (Req (_, e)) -> is_zeroable e (* represented as-is *)
| Obj (Opt (`Variable, _, _)) -> true (* optional field ommited *)
| Obj (Dft (_, e, _)) -> is_zeroable e (* represented as-is *)
| Obj _ -> false
| Objs (_, e1, e2) -> is_zeroable e1 && is_zeroable e2
| Tup e -> is_zeroable e
| Tups (_, e1, e2) -> is_zeroable e1 && is_zeroable e2
| Union (_, _, _) -> false (* includes a tag *)
(* other recursive cases: truth propagates *)
| Mu (`Dynamic, _, _) -> false (* size prefix *)
| Mu (`Variable, _, f) -> is_zeroable (f e)
| Conv { encoding } -> is_zeroable encoding
| Describe { encoding } -> is_zeroable encoding
| Def { encoding } -> is_zeroable encoding
| Splitted { encoding } -> is_zeroable encoding
| Check_size { encoding } -> is_zeroable encoding
(* Unscrutable: true by default *)
| Delayed f -> is_zeroable (f ())
(* Protected against zeroable *)
| Dynamic_size _ -> false (* always some data for size *)
module Variable = struct
let string = make @@ String `Variable
let bytes = make @@ Bytes `Variable
@ -191,11 +250,19 @@ module Variable = struct
"Cannot insert variable length element in %s. \
You should wrap the contents using Data_encoding.dynamic_size." name
| `Dynamic | `Fixed _ -> ()
let check_not_zeroable name e =
if is_zeroable e then
Printf.ksprintf invalid_arg
"Cannot insert potentially zero-sized element in %s." name
else
()
let array e =
check_not_variable "an array" e ;
check_not_zeroable "an array" e ;
make @@ Array e
let list e =
check_not_variable "a list" e ;
check_not_zeroable "a list" e ;
make @@ List e
end