sots-engine/tests/shim_events/unit_tests.cpp

// P adapter tests: read a live-shaped Game::EventStorage out of raw bytes, seed the model from
// it, and write the counts back the way compare mode does.
//
// The fixture is a byte buffer laid out with the *real* offsets from the generated header
// (EventStorage 0x1c / TurnEvents 0x18 / PlayerEvent 0x74, MSVC-2010 std::string 0x1c), so these
// cases pin the nested turn-bucketed shape and the stride, not just the arithmetic. The shape is
// the one verify/results/saves/turn3-state.sav holds for player 1 and the one
// verify/state-checksum/state_checksum.py walks: EvNxID, then n x {EvTurn, m x PlayerEvent}.
#include "shim/hooks/event_inputs.h"

#include <cstdint>
#include <cstring>
#include <string>
#include <vector>

#include "check.h"
#include "game/events/research_events.h"
#include "generated/sots_addresses.h"

using namespace shim::hooks;
namespace A = sots::addr;

namespace {

// ---- a fake address space -----------------------------------------------------------------
//
// One arena; `probe` answers "is this range inside it?", which is the host stand-in for the
// shim's VirtualQuery. Everything the adapter reads must go through it.
std::vector<char>& arena() {
    static std::vector<char> a;
    return a;
}

bool probe(const void* p, std::size_t n) {
    if (!p) return false;
    if (n == 0) return true;
    const char* c = static_cast<const char*>(p);
    const char* lo = arena().data();
    const char* hi = lo + arena().size();
    return c >= lo && c + n <= hi && c + n >= c;
}

void put_word(std::size_t off, std::int32_t v) { std::memcpy(&arena()[off], &v, sizeof v); }

// A pointer *inside a game object* is four bytes, and in this fake address space a game address
// is simply an offset into the arena, biased so that 0 stays "null".
constexpr std::uint32_t kArenaBias = 0x40000000;
void put_addr(std::size_t off, std::size_t targetOff) {
    const std::uint32_t a = kArenaBias + static_cast<std::uint32_t>(targetOff);
    std::memcpy(&arena()[off], &a, sizeof a);
}
void put_addr_raw(std::size_t off, std::uint32_t a) { std::memcpy(&arena()[off], &a, sizeof a); }
void put_null(std::size_t off) { put_addr_raw(off, 0); }

const void* to_host(std::uint32_t a) {
    if (a < kArenaBias) return nullptr;  // not one of ours: the probe will reject it
    const std::size_t off = a - kArenaBias;
    if (off > arena().size()) return nullptr;
    return arena().data() + off;
}

// An MSVC 2010 std::string at `off`, short enough to live in the inline buffer (_Myres 15).
void put_short_string(std::size_t off, const std::string& s) {
    CHECK(s.size() < kStdStringInlineCap);
    std::memcpy(&arena()[off], s.data(), s.size());
    arena()[off + s.size()] = '\0';
    put_word(off + kStdStringOffSize, static_cast<std::int32_t>(s.size()));
    put_word(off + kStdStringOffRes, static_cast<std::int32_t>(kStdStringInlineCap - 1));
}

// The same string, but heap-allocated: _Myres >= 16 and the first word is the pointer. Every
// EvImg in a real save takes this form -- "EVENT_RESEARCH_OVERBUDGET" is 25 characters -- so it
// is the form that actually matters, and reading the inline buffer instead yields garbage.
void put_long_string(std::size_t off, std::size_t bufOff, const std::string& s) {
    std::memcpy(&arena()[bufOff], s.data(), s.size());
    arena()[bufOff + s.size()] = '\0';
    put_addr(off, bufOff);
    put_word(off + kStdStringOffSize, static_cast<std::int32_t>(s.size()));
    put_word(off + kStdStringOffRes, static_cast<std::int32_t>(s.size() + 8));
}

// Pick the form the real string would take.
void put_string(std::size_t off, std::size_t bufOff, const std::string& s) {
    if (s.size() < kStdStringInlineCap)
        put_short_string(off, s);
    else
        put_long_string(off, bufOff, s);
}

// ---- the fixture ----------------------------------------------------------------------------
//
// Layout inside the arena:
//   0x0000  EventStorage        (0x1c)
//   0x0100  TurnEvents[]        (0x18 each)
//   0x0400  PlayerEvent[] for bucket 1  (0x74 each)
//   0x1000  string heap
constexpr std::size_t kStorage = 0x0000;
constexpr std::size_t kBuckets = 0x0100;
constexpr std::size_t kEvents = 0x0400;
constexpr std::size_t kHeap = 0x1000;

// `images` is one EvImg per event in the *second* bucket; the first bucket is left empty.
void build(int nextId, const std::vector<int>& bucketTurns, const std::vector<std::string>& images,
           std::size_t whichBucketHasEvents) {
    arena().assign(0x2000, 0);
    put_word(kStorage + A::EventStorage_off_EvNxID, nextId);
    if (bucketTurns.empty()) {
        put_null(kStorage + A::EventStorage_off_Events);
        put_null(kStorage + A::EventStorage_off_Events + kGamePtrSize);
        put_null(kStorage + A::EventStorage_off_Events + 2 * kGamePtrSize);
        return;
    }
    const std::size_t bytes = bucketTurns.size() * A::TurnEvents_sizeof;
    put_addr(kStorage + A::EventStorage_off_Events, kBuckets);
    put_addr(kStorage + A::EventStorage_off_Events + kGamePtrSize, kBuckets + bytes);
    put_addr(kStorage + A::EventStorage_off_Events + 2 * kGamePtrSize, kBuckets + bytes);

    for (std::size_t i = 0; i < bucketTurns.size(); ++i) {
        const std::size_t b = kBuckets + i * A::TurnEvents_sizeof;
        put_word(b + A::TurnEvents_off_EvTurn, bucketTurns[i]);
        if (i != whichBucketHasEvents || images.empty()) {
            put_null(b + A::TurnEvents_off_Events);
            put_null(b + A::TurnEvents_off_Events + kGamePtrSize);
            put_null(b + A::TurnEvents_off_Events + 2 * kGamePtrSize);
            continue;
        }
        const std::size_t evBytes = images.size() * A::PlayerEvent_sizeof;
        put_addr(b + A::TurnEvents_off_Events, kEvents);
        put_addr(b + A::TurnEvents_off_Events + kGamePtrSize, kEvents + evBytes);
        put_addr(b + A::TurnEvents_off_Events + 2 * kGamePtrSize, kEvents + evBytes);
        for (std::size_t k = 0; k < images.size(); ++k) {
            const std::size_t img = kEvents + k * A::PlayerEvent_sizeof + A::PlayerEvent_off_EvImg;
            put_string(img, kHeap + k * 0x40, images[k]);
        }
    }
}

const void* storage() { return arena().data() + kStorage; }

// Read the turns vector's {first, last} back out of a scratch header, as 32-bit game addresses.
std::size_t scratch_turns_bytes(const std::vector<char>& scratch) {
    std::uint32_t first = 0, last = 0;
    std::memcpy(&first, scratch.data() + A::EventStorage_off_Events, sizeof first);
    std::memcpy(&last, scratch.data() + A::EventStorage_off_Events + kGamePtrSize, sizeof last);
    CHECK(last >= first);
    return last - first;
}
std::uint32_t scratch_turns_first(const std::vector<char>& scratch) {
    std::uint32_t first = 0;
    std::memcpy(&first, scratch.data() + A::EventStorage_off_Events, sizeof first);
    return first;
}
// The write-back runs on a scratch buffer, not on the arena, so it gets its own probe.
bool scratch_probe(const void* p, std::size_t n) { return p != nullptr && n <= 0x100; }

// ---- cases ------------------------------------------------------------------------------------

// turn3-state.sav, player 1: EvNxID 4, buckets for turns 2 and 3, the turn-3 bucket holding
// EVENT_SHIPS_BUILT and EVENT_RESEARCH_OVERBUDGET.
void test_scan_reads_the_real_save_shape() {
    build(4, {2, 3}, {"EVENT_SHIPS_BUILT", "EVENT_RESEARCH_OVERBUDGET"}, 1);
    const EventStorageScan s = ScanEventStorage(storage(), 3, &probe, &to_host);
    CHECK(s.ok);
    CHECK(!s.scanTruncated);
    CHECK_EQ(s.nextId, 4);
    CHECK_EQ(s.bucketTurns.size(), 2u);
    CHECK_EQ(s.bucketTurns[0], 2);
    CHECK_EQ(s.bucketTurns[1], 3);
    CHECK_EQ(s.turnsBytes, 2u * A::TurnEvents_sizeof);
    CHECK(s.turnBucketExists);
    CHECK_EQ(s.eventsInTurnBucket, 2u);
    // Only the research event counts towards the dedup risk; EVENT_SHIPS_BUILT can never be a
    // duplicate of anything the research path posts.
    CHECK_EQ(s.researchEventsInTurnBucket, 1u);
}

// The pre-call state of recap-b3-compare call 0: EvNxID 3 and no research event in the bucket
// yet -- so a count-only model is exact on that call.
void test_scan_reports_no_dedup_risk_before_the_post() {
    build(3, {2, 3}, {"EVENT_SHIPS_BUILT"}, 1);
    const EventStorageScan s = ScanEventStorage(storage(), 3, &probe, &to_host);
    CHECK_EQ(s.nextId, 3);
    CHECK_EQ(s.researchEventsInTurnBucket, 0u);
    CHECK_EQ(s.eventsInTurnBucket, 1u);
}

// A player who has never seen an event: EvNxID 0 and {null,null,null}. Two of the four players
// in the reference save look exactly like this.
void test_scan_of_an_empty_storage() {
    build(0, {}, {}, 0);
    const EventStorageScan s = ScanEventStorage(storage(), 3, &probe, &to_host);
    CHECK(s.ok);
    CHECK_EQ(s.nextId, 0);
    CHECK_EQ(s.bucketTurns.size(), 0u);
    CHECK_EQ(s.turnsBytes, 0u);
    CHECK(!s.turnBucketExists);
}

// The heap form of std::string must read the same as the inline form.
void test_scan_reads_heap_strings() {
    build(4, {3}, {"EVENT_RESEARCH_UNDERBUDGET"}, 0);
    const EventStorageScan s = ScanEventStorage(storage(), 3, &probe, &to_host);
    CHECK(s.ok);
    CHECK_EQ(s.researchEventsInTurnBucket, 1u);
}

// A header that is not a vector must not be believed, and must not walk off the arena.
void test_scan_rejects_a_bad_header() {
    build(4, {3}, {}, 0);
    // last < first
    put_addr(kStorage + A::EventStorage_off_Events, kBuckets + A::TurnEvents_sizeof);
    put_addr(kStorage + A::EventStorage_off_Events + kGamePtrSize, kBuckets);
    CHECK(!ScanEventStorage(storage(), 3, &probe, &to_host).ok);

    // a span that is not a whole number of TurnEvents
    build(4, {3}, {}, 0);
    put_addr(kStorage + A::EventStorage_off_Events + kGamePtrSize, kBuckets + 7);
    CHECK(!ScanEventStorage(storage(), 3, &probe, &to_host).ok);

    // a span far larger than the arena
    build(4, {3}, {}, 0);
    put_addr(kStorage + A::EventStorage_off_Events + kGamePtrSize,
             kBuckets + (kMaxTurnBuckets + 1) * A::TurnEvents_sizeof);
    const EventStorageScan s = ScanEventStorage(storage(), 3, &probe, &to_host);
    CHECK(!s.ok);
}

// ---- seed + post + write back: the whole compare-mode path -----------------------------------

// recap-b3-compare call 0, end to end. THE case: EvNxID 3 -> 4 with one over-budget post, and
// `turns` unchanged because the turn-3 bucket already existed.
void test_overbudget_call_reaches_next_id_4() {
    build(3, {2, 3}, {"EVENT_SHIPS_BUILT"}, 1);
    const EventStorageScan s = ScanEventStorage(storage(), 3, &probe, &to_host);
    CHECK_EQ(s.researchEventsInTurnBucket, 0u);  // count-only is exact here

    sots::events::EventStorage log = SeedFromScan(s);
    CHECK_EQ(log.nextId(), 3);
    CHECK_EQ(log.turns().size(), 2u);

    std::vector<sots::events::ResearchPassOutcome> out(1);
    out[0].techName = "144";
    out[0].overbudgetEvent = true;
    const sots::events::ResearchPassResult r =
        sots::events::PostResearchPassEvents(log, sots::events::KeylessEventText(), out, nullptr, 3);
    CHECK_EQ(r.nextId, 4);

    // The scratch copy the region diff reads is a byte copy of the header.
    std::vector<char> scratch(A::EventStorage_sizeof);
    std::memcpy(scratch.data(), storage(), scratch.size());
    WriteBackCounts(scratch.data(), log, &scratch_probe);

    std::int32_t nextId = 0;
    std::memcpy(&nextId, scratch.data() + A::EventStorage_off_EvNxID, 4);
    CHECK_EQ(nextId, 4);
    CHECK_EQ(scratch_turns_bytes(scratch), 2u * A::TurnEvents_sizeof);
}

// The same pass on a turn with no bucket yet: `turns` must grow by one, which is what the
// region's turns_bytes reports.
void test_write_back_grows_turns_when_a_bucket_is_created() {
    build(3, {2}, {}, 0);
    const EventStorageScan s = ScanEventStorage(storage(), 9, &probe, &to_host);
    CHECK(!s.turnBucketExists);
    sots::events::EventStorage log = SeedFromScan(s);
    std::vector<sots::events::ResearchPassOutcome> out(1);
    out[0].techName = "144";
    out[0].overbudgetEvent = true;
    sots::events::PostResearchPassEvents(log, sots::events::KeylessEventText(), out, nullptr, 9);
    CHECK_EQ(log.turns().size(), 2u);

    std::vector<char> scratch(A::EventStorage_sizeof);
    std::memcpy(scratch.data(), storage(), scratch.size());
    WriteBackCounts(scratch.data(), log, &scratch_probe);
    CHECK_EQ(scratch_turns_bytes(scratch), 2u * A::TurnEvents_sizeof);
}

// A previously empty storage: the header has no pointers to extend, so the write-back has to
// synthesise a base or the span would read 0 where the original allocated one bucket.
void test_write_back_on_a_previously_empty_storage() {
    build(0, {}, {}, 0);
    const EventStorageScan s = ScanEventStorage(storage(), 3, &probe, &to_host);
    sots::events::EventStorage log = SeedFromScan(s);
    CHECK_EQ(log.nextId(), 0);
    std::vector<sots::events::ResearchPassOutcome> out(1);
    out[0].techName = "144";
    out[0].overbudgetEvent = true;
    sots::events::PostResearchPassEvents(log, sots::events::KeylessEventText(), out, nullptr, 3);

    std::vector<char> scratch(A::EventStorage_sizeof);
    std::memcpy(scratch.data(), storage(), scratch.size());
    WriteBackCounts(scratch.data(), log, &scratch_probe);
    std::int32_t nextId = 0;
    std::memcpy(&nextId, scratch.data() + A::EventStorage_off_EvNxID, 4);
    CHECK_EQ(nextId, 2);  // 0 -> promoted to 1 by the post -> post-incremented
    CHECK_EQ(scratch_turns_first(scratch), kSyntheticTurnsBase);
    CHECK_EQ(scratch_turns_bytes(scratch), 1u * A::TurnEvents_sizeof);
}

// A zero-spend call must leave the header byte-identical: no id, no bucket.
void test_write_back_is_a_no_op_when_nothing_posted() {
    build(3, {2, 3}, {"EVENT_SHIPS_BUILT"}, 1);
    const EventStorageScan s = ScanEventStorage(storage(), 3, &probe, &to_host);
    sots::events::EventStorage log = SeedFromScan(s);
    std::vector<sots::events::ResearchPassOutcome> out(2);
    out[0].techName = "90";
    out[1].techName = "9";
    sots::events::PostResearchPassEvents(log, sots::events::KeylessEventText(), out, nullptr, 3);

    std::vector<char> before(A::EventStorage_sizeof), scratch(A::EventStorage_sizeof);
    std::memcpy(before.data(), storage(), before.size());
    std::memcpy(scratch.data(), storage(), scratch.size());
    WriteBackCounts(scratch.data(), log, &scratch_probe);
    CHECK(std::memcmp(before.data(), scratch.data(), before.size()) == 0);
}

// Both std::string forms read the same, and a misread is reported rather than guessed at.
void test_read_std_string_forms_and_bounds() {
    arena().assign(0x200, 0);
    std::string out = "untouched";
    put_short_string(0, "EVENT_X");
    CHECK(ReadStdStringMapped(arena().data(), &probe, &to_host, out));
    CHECK(out == "EVENT_X");

    // The heap form -- what every real EvImg uses.
    arena().assign(0x200, 0);
    put_long_string(0, 0x80, "EVENT_RESEARCH_OVERBUDGET");
    out = "untouched";
    CHECK(ReadStdStringMapped(arena().data(), &probe, &to_host, out));
    CHECK(out == "EVENT_RESEARCH_OVERBUDGET");

    // A length past the sanity cap.
    put_word(kStdStringOffSize, 0x2000);
    out = "untouched";
    CHECK(!ReadStdStringMapped(arena().data(), &probe, &to_host, out));
    CHECK(out == "untouched");

    // _Myres < _Mysize is impossible in a well-formed string.
    arena().assign(0x200, 0);
    put_long_string(0, 0x80, "EVENT_RESEARCH_OVERBUDGET");
    put_word(kStdStringOffRes, 4);
    CHECK(!ReadStdStringMapped(arena().data(), &probe, &to_host, out));

    // A heap string whose buffer address is not in the arena at all.
    arena().assign(0x200, 0);
    put_addr_raw(0, 0xdead0000);
    put_word(kStdStringOffSize, 8);
    put_word(kStdStringOffRes, 31);
    CHECK(!ReadStdStringMapped(arena().data(), &probe, &to_host, out));
}

}  // namespace

int main() {
    test_scan_reads_the_real_save_shape();
    test_scan_reports_no_dedup_risk_before_the_post();
    test_scan_of_an_empty_storage();
    test_scan_reads_heap_strings();
    test_scan_rejects_a_bad_header();
    test_overbudget_call_reaches_next_id_4();
    test_write_back_grows_turns_when_a_bucket_is_created();
    test_write_back_on_a_previously_empty_storage();
    test_write_back_is_a_no_op_when_nothing_posted();
    test_read_std_string_forms_and_bounds();
    return simtest::finish("shim_events");
}