Index: node_modules/sqlite3/src/backup.cc
===================================================================
--- node_modules/sqlite3/src/backup.cc	(revision 81bc7da776d8cda42939ef4ab350c88d13b4941f)
+++ node_modules/sqlite3/src/backup.cc	(revision 81bc7da776d8cda42939ef4ab350c88d13b4941f)
@@ -0,0 +1,418 @@
+#include <cstring>
+#include <napi.h>
+#include "macros.h"
+#include "database.h"
+#include "backup.h"
+
+using namespace node_sqlite3;
+
+Napi::Object Backup::Init(Napi::Env env, Napi::Object exports) {
+    Napi::HandleScope scope(env);
+
+    // declare napi_default_method here as it is only available in Node v14.12.0+
+    auto napi_default_method = static_cast<napi_property_attributes>(napi_writable | napi_configurable);
+
+    auto t = DefineClass(env, "Backup", {
+        InstanceMethod("step", &Backup::Step, napi_default_method),
+        InstanceMethod("finish", &Backup::Finish, napi_default_method),
+        InstanceAccessor("idle", &Backup::IdleGetter, nullptr),
+        InstanceAccessor("completed", &Backup::CompletedGetter, nullptr),
+        InstanceAccessor("failed", &Backup::FailedGetter, nullptr),
+        InstanceAccessor("remaining", &Backup::RemainingGetter, nullptr),
+        InstanceAccessor("pageCount", &Backup::PageCountGetter, nullptr),
+        InstanceAccessor("retryErrors", &Backup::RetryErrorGetter, &Backup::RetryErrorSetter),
+    });
+
+    exports.Set("Backup", t);
+    return exports;
+}
+
+void Backup::Process() {
+    if (finished && !queue.empty()) {
+        return CleanQueue();
+    }
+
+    while (inited && !locked && !queue.empty()) {
+        auto call = std::move(queue.front());
+        queue.pop();
+
+        call->callback(call->baton);
+    }
+}
+
+void Backup::Schedule(Work_Callback callback, Baton* baton) {
+    if (finished) {
+        queue.emplace(new Call(callback, baton));
+        CleanQueue();
+    }
+    else if (!inited || locked || !queue.empty()) {
+        queue.emplace(new Call(callback, baton));
+    }
+    else {
+        callback(baton);
+    }
+}
+
+template <class T> void Backup::Error(T* baton) {
+    auto env = baton->backup->Env();
+    Napi::HandleScope scope(env);
+
+    Backup* backup = baton->backup;
+    // Fail hard on logic errors.
+    assert(backup->status != 0);
+    EXCEPTION(Napi::String::New(env, backup->message), backup->status, exception);
+
+    Napi::Function cb = baton->callback.Value();
+
+    if (!cb.IsEmpty() && cb.IsFunction()) {
+        Napi::Value argv[] = { exception };
+        TRY_CATCH_CALL(backup->Value(), cb, 1, argv);
+    }
+    else {
+        Napi::Value argv[] = { Napi::String::New(env, "error"), exception };
+        EMIT_EVENT(backup->Value(), 2, argv);
+    }
+}
+
+void Backup::CleanQueue() {
+    auto env = this->Env();
+    Napi::HandleScope scope(env);
+
+    if (inited && !queue.empty()) {
+        // This backup has already been initialized and is now finished.
+        // Fire error for all remaining items in the queue.
+        EXCEPTION(Napi::String::New(env, "Backup is already finished"), SQLITE_MISUSE, exception);
+        Napi::Value argv[] = { exception };
+        bool called = false;
+
+        // Clear out the queue so that this object can get GC'ed.
+        while (!queue.empty()) {
+            auto call = std::move(queue.front());
+            queue.pop();
+
+            std::unique_ptr<Baton> baton(call->baton);
+            Napi::Function cb = baton->callback.Value();
+
+            if (inited && !cb.IsEmpty() &&
+                cb.IsFunction()) {
+                TRY_CATCH_CALL(Value(), cb, 1, argv);
+                called = true;
+            }
+        }
+
+        // When we couldn't call a callback function, emit an error on the
+        // Backup object.
+        if (!called) {
+            Napi::Value info[] = { Napi::String::New(env, "error"), exception };
+            EMIT_EVENT(Value(), 2, info);
+        }
+    }
+    else while (!queue.empty()) {
+        // Just delete all items in the queue; we already fired an event when
+        // initializing the backup failed.
+        auto call = std::move(queue.front());
+        queue.pop();
+
+        // We don't call the actual callback, so we have to make sure that
+        // the baton gets destroyed.
+        delete call->baton;
+    }
+}
+
+Backup::Backup(const Napi::CallbackInfo& info) : Napi::ObjectWrap<Backup>(info) {
+    auto env = info.Env();
+    if (!info.IsConstructCall()) {
+        Napi::TypeError::New(env, "Use the new operator to create new Backup objects").ThrowAsJavaScriptException();
+        return;
+    }
+
+    auto length = info.Length();
+
+    if (length <= 0 || !Database::HasInstance(info[0])) {
+        Napi::TypeError::New(env, "Database object expected").ThrowAsJavaScriptException();
+        return;
+    }
+    else if (length <= 1 || !info[1].IsString()) {
+        Napi::TypeError::New(env, "Filename expected").ThrowAsJavaScriptException();
+        return;
+    }
+    else if (length <= 2 || !info[2].IsString()) {
+        Napi::TypeError::New(env, "Source database name expected").ThrowAsJavaScriptException();
+        return;
+    }
+    else if (length <= 3 || !info[3].IsString()) {
+        Napi::TypeError::New(env, "Destination database name expected").ThrowAsJavaScriptException();
+        return;
+    }
+    else if (length <= 4 || !info[4].IsBoolean()) {
+        Napi::TypeError::New(env, "Direction flag expected").ThrowAsJavaScriptException();
+        return;
+    }
+    else if (length > 5 && !info[5].IsUndefined() && !info[5].IsFunction()) {
+        Napi::TypeError::New(env, "Callback expected").ThrowAsJavaScriptException();
+        return;
+    }
+
+    this->db = Napi::ObjectWrap<Database>::Unwrap(info[0].As<Napi::Object>());
+    this->db->Ref();
+
+    auto filename = info[1].As<Napi::String>();
+    auto sourceName = info[2].As<Napi::String>();
+    auto destName = info[3].As<Napi::String>();
+    auto filenameIsDest = info[4].As<Napi::Boolean>();
+
+    info.This().As<Napi::Object>().DefineProperty(Napi::PropertyDescriptor::Value("filename", filename));
+    info.This().As<Napi::Object>().DefineProperty(Napi::PropertyDescriptor::Value("sourceName", sourceName));
+    info.This().As<Napi::Object>().DefineProperty(Napi::PropertyDescriptor::Value("destName", destName));
+    info.This().As<Napi::Object>().DefineProperty(Napi::PropertyDescriptor::Value("filenameIsDest", filenameIsDest));
+
+    auto* baton = new InitializeBaton(this->db, info[5].As<Napi::Function>(), this);
+    baton->filename = filename.Utf8Value();
+    baton->sourceName = sourceName.Utf8Value();
+    baton->destName = destName.Utf8Value();
+    baton->filenameIsDest = filenameIsDest.Value();
+
+    this->db->Schedule(Work_BeginInitialize, baton);
+}
+
+void Backup::Work_BeginInitialize(Database::Baton* baton) {
+    assert(baton->db->open);
+    baton->db->pending++;
+    auto env = baton->db->Env();
+    CREATE_WORK("sqlite3.Backup.Initialize", Work_Initialize, Work_AfterInitialize);
+}
+
+void Backup::Work_Initialize(napi_env e, void* data) {
+    BACKUP_INIT(InitializeBaton);
+
+    // In case stepping fails, we use a mutex to make sure we get the associated
+    // error message.
+    auto* mtx = sqlite3_db_mutex(baton->db->_handle);
+    sqlite3_mutex_enter(mtx);
+
+    backup->status = sqlite3_open(baton->filename.c_str(), &backup->_otherDb);
+
+    if (backup->status == SQLITE_OK) {
+        backup->_handle = sqlite3_backup_init(
+            baton->filenameIsDest ? backup->_otherDb : backup->db->_handle,
+            baton->destName.c_str(),
+            baton->filenameIsDest ? backup->db->_handle : backup->_otherDb,
+            baton->sourceName.c_str());
+    }
+    backup->_destDb = baton->filenameIsDest ? backup->_otherDb : backup->db->_handle;
+
+    if (backup->status != SQLITE_OK) {
+        backup->message = std::string(sqlite3_errmsg(backup->_destDb));
+        sqlite3_close(backup->_otherDb);
+        backup->_otherDb = NULL;
+        backup->_destDb = NULL;
+    }
+
+    sqlite3_mutex_leave(mtx);
+}
+
+void Backup::Work_AfterInitialize(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<InitializeBaton> baton(static_cast<InitializeBaton*>(data));
+    auto* backup = baton->backup;
+
+    auto env = backup->Env();
+    Napi::HandleScope scope(env);
+
+    if (backup->status != SQLITE_OK) {
+        Error(baton.get());
+        backup->FinishAll();
+    }
+    else {
+        backup->inited = true;
+        Napi::Function cb = baton->callback.Value();
+        if (!cb.IsEmpty() && cb.IsFunction()) {
+            Napi::Value argv[] = { env.Null() };
+            TRY_CATCH_CALL(backup->Value(), cb, 1, argv);
+        }
+    }
+    BACKUP_END();
+}
+
+Napi::Value Backup::Step(const Napi::CallbackInfo& info) {
+    auto* backup = this;
+    auto env = backup->Env();
+
+    REQUIRE_ARGUMENT_INTEGER(0, pages);
+    OPTIONAL_ARGUMENT_FUNCTION(1, callback);
+
+    auto* baton = new StepBaton(backup, callback, pages);
+    backup->GetRetryErrors(baton->retryErrorsSet);
+    backup->Schedule(Work_BeginStep, baton);
+    return info.This();
+}
+
+void Backup::Work_BeginStep(Baton* baton) {
+    BACKUP_BEGIN(Step);
+}
+
+void Backup::Work_Step(napi_env e, void* data) {
+    BACKUP_INIT(StepBaton);
+    if (backup->_handle) {
+        backup->status = sqlite3_backup_step(backup->_handle, baton->pages);
+        backup->remaining = sqlite3_backup_remaining(backup->_handle);
+        backup->pageCount = sqlite3_backup_pagecount(backup->_handle);
+    }
+    if (backup->status != SQLITE_OK) {
+        // Text of message is a little awkward to get, since the error is not associated
+        // with a db connection.
+#if SQLITE_VERSION_NUMBER >= 3007015
+        // sqlite3_errstr is a relatively new method
+        backup->message = std::string(sqlite3_errstr(backup->status));
+#else
+        backup->message = "Sqlite error";
+#endif
+        if (baton->retryErrorsSet.size() > 0) {
+            if (baton->retryErrorsSet.find(backup->status) == baton->retryErrorsSet.end()) {
+                backup->FinishSqlite();
+            }
+        }
+    }
+}
+
+void Backup::Work_AfterStep(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<StepBaton> baton(static_cast<StepBaton*>(data));
+    auto* backup = baton->backup;
+
+    auto env = backup->Env();
+    Napi::HandleScope scope(env);
+
+    if (backup->status == SQLITE_DONE) {
+        backup->completed = true;
+    } else if (!backup->_handle) {
+        backup->failed = true;
+    }
+
+    if (backup->status != SQLITE_OK && backup->status != SQLITE_DONE) {
+        Error(baton.get());
+    }
+    else {
+        // Fire callbacks.
+        Napi::Function cb = baton->callback.Value();
+        if (!cb.IsEmpty() && cb.IsFunction()) {
+            Napi::Value argv[] = { env.Null(), Napi::Boolean::New(env, backup->status == SQLITE_DONE) };
+            TRY_CATCH_CALL(backup->Value(), cb, 2, argv);
+        }
+    }
+
+    BACKUP_END();
+}
+
+Napi::Value Backup::Finish(const Napi::CallbackInfo& info) {
+    auto* backup = this;
+    auto env = backup->Env();
+
+    OPTIONAL_ARGUMENT_FUNCTION(0, callback);
+
+    auto* baton = new Baton(backup, callback);
+    backup->Schedule(Work_BeginFinish, baton);
+    return info.This();
+}
+
+void Backup::Work_BeginFinish(Baton* baton) {
+    BACKUP_BEGIN(Finish);
+}
+
+void Backup::Work_Finish(napi_env e, void* data) {
+    BACKUP_INIT(Baton);
+    backup->FinishSqlite();
+}
+
+void Backup::Work_AfterFinish(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<Baton> baton(static_cast<Baton*>(data));
+    auto* backup = baton->backup;
+
+    auto env = backup->Env();
+    Napi::HandleScope scope(env);
+
+    backup->FinishAll();
+
+    // Fire callback in case there was one.
+    Napi::Function cb = baton->callback.Value();
+    if (!cb.IsEmpty() && cb.IsFunction()) {
+        TRY_CATCH_CALL(backup->Value(), cb, 0, NULL);
+    }
+
+    BACKUP_END();
+}
+
+void Backup::FinishAll() {
+    assert(!finished);
+    if (!completed && !failed) {
+        failed = true;
+    }
+    finished = true;
+    CleanQueue();
+    FinishSqlite();
+    db->Unref();
+}
+
+void Backup::FinishSqlite() {
+    if (_handle) {
+        sqlite3_backup_finish(_handle);
+        _handle = NULL;
+    }
+    if (_otherDb) {
+        sqlite3_close(_otherDb);
+        _otherDb = NULL;
+    }
+    _destDb = NULL;
+}
+
+Napi::Value Backup::IdleGetter(const Napi::CallbackInfo& info) {
+    auto* backup = this;
+    bool idle = backup->inited && !backup->locked && backup->queue.empty();
+    return Napi::Boolean::New(this->Env(), idle);
+}
+
+Napi::Value Backup::CompletedGetter(const Napi::CallbackInfo& info) {
+    auto* backup = this;
+    return Napi::Boolean::New(this->Env(), backup->completed);
+}
+
+Napi::Value Backup::FailedGetter(const Napi::CallbackInfo& info) {
+    auto* backup = this;
+    return Napi::Boolean::New(this->Env(), backup->failed);
+}
+
+Napi::Value Backup::RemainingGetter(const Napi::CallbackInfo& info) {
+    auto* backup = this;
+    return Napi::Number::New(this->Env(), backup->remaining);
+}
+
+Napi::Value Backup::PageCountGetter(const Napi::CallbackInfo& info) {
+    auto* backup = this;
+    return Napi::Number::New(this->Env(), backup->pageCount);
+}
+
+Napi::Value Backup::RetryErrorGetter(const Napi::CallbackInfo& info) {
+    auto* backup = this;
+    return backup->retryErrors.Value();
+}
+
+void Backup::RetryErrorSetter(const Napi::CallbackInfo& info, const Napi::Value& value) {
+    auto* backup = this;
+    auto env = backup->Env();
+    if (!value.IsArray()) {
+        Napi::Error::New(env, "retryErrors must be an array").ThrowAsJavaScriptException();
+        return;
+    }
+    Napi::Array array = value.As<Napi::Array>();
+    backup->retryErrors.Reset(array, 1);
+}
+
+void Backup::GetRetryErrors(std::set<int>& retryErrorsSet) {
+    retryErrorsSet.clear();
+    Napi::Array array = retryErrors.Value();
+    auto length = array.Length();
+    for (size_t i = 0; i < length; i++) {
+        Napi::Value code = (array).Get(static_cast<uint32_t>(i));
+        if (code.IsNumber()) {
+            retryErrorsSet.insert(code.As<Napi::Number>().Int32Value());
+        }
+    }
+}