selinux/new_policy/
traits.rs

1// Copyright 2026 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use super::NewPolicy;
6use super::error::{ParseError, SerializeError, ValidateError};
7use super::parser::PolicyCursor;
8
9/// Trait for types that can be parsed from a [`PolicyCursor`].
10pub trait Parse: Sized {
11    fn parse(cursor: &mut PolicyCursor<'_>) -> Result<Self, ParseError>;
12}
13
14/// Trait for types that can be serialized into a byte vector.
15pub trait Serialize {
16    fn serialize(&self, writer: &mut Vec<u8>) -> Result<(), SerializeError>;
17}
18
19/// Trait for types that can be validated against the parsed policy.
20pub trait Validate {
21    fn validate(&self, policy: &NewPolicy) -> Result<(), ValidateError>;
22}
23
24/// Trait for strongly-typed policy identifiers.
25///
26/// Types implementing [`PolicyId`] can be parsed from and serialized to `u32` values
27/// in the binary policy database, but are represented as strongly-typed integers
28/// (often wrapping `NonZeroU16` or `NonZeroU32`) in the logical domain model.
29pub trait PolicyId: Copy + Clone + std::fmt::Debug + Eq + std::hash::Hash + PartialEq {
30    /// Returns the raw `u32` value of the ID.
31    fn as_u32(&self) -> u32;
32
33    /// Constructs an instance of [`Self`] from a raw `u32` value, returning [`None`]
34    /// if the value is invalid (e.g. zero for a non-optional ID, or out of range).
35    fn from_u32(value: u32) -> Option<Self>;
36}
37
38// Blanket implementations for all strongly-typed IDs
39impl<T> Parse for T
40where
41    T: PolicyId,
42{
43    fn parse(cursor: &mut PolicyCursor<'_>) -> Result<Self, ParseError> {
44        let value = u32::parse(cursor)?;
45        T::from_u32(value).ok_or(ParseError::InvalidId { value })
46    }
47}
48
49impl<T> Serialize for T
50where
51    T: PolicyId,
52{
53    fn serialize(&self, writer: &mut Vec<u8>) -> Result<(), SerializeError> {
54        self.as_u32().serialize(writer)
55    }
56}
57
58/// Trait for policy elements with a byte slice name.
59pub trait HasName {
60    fn name(&self) -> &[u8];
61}
62
63/// Trait for policy elements that have a strongly-typed policy identifier.
64pub trait HasPolicyId {
65    type Id: PolicyId;
66    fn id(&self) -> Self::Id;
67}
68
69impl Validate for Box<[u8]> {
70    fn validate(&self, _policy: &NewPolicy) -> Result<(), ValidateError> {
71        Ok(())
72    }
73}
74
75impl<T: Validate> Validate for Box<T> {
76    fn validate(&self, policy: &NewPolicy) -> Result<(), ValidateError> {
77        (**self).validate(policy)
78    }
79}
80
81impl Validate for bool {
82    fn validate(&self, _policy: &NewPolicy) -> Result<(), ValidateError> {
83        Ok(())
84    }
85}
86
87impl<T: Validate> Validate for Option<T> {
88    fn validate(&self, policy: &NewPolicy) -> Result<(), ValidateError> {
89        if let Some(value) = self {
90            value.validate(policy)?;
91        }
92        Ok(())
93    }
94}
selinux/new_policy/traits.rs

selinux/new_policy/
traits.rs
