Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 800 insertions, 0 deletions

diff --git a/browser/components/migration/ESEDBReader.sys.mjs b/browser/components/migration/ESEDBReader.sys.mjs
new file mode 100644
index 0000000000..53cff13636
--- /dev/null
+++ b/browser/components/migration/ESEDBReader.sys.mjs
@@ -0,0 +1,800 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+import { ctypes } from "resource://gre/modules/ctypes.sys.mjs";
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+const lazy = {};
+XPCOMUtils.defineLazyGetter(lazy, "log", () => {
+  let { ConsoleAPI } = ChromeUtils.importESModule(
+    "resource://gre/modules/Console.sys.mjs"
+  );
+  let consoleOptions = {
+    maxLogLevelPref: "browser.esedbreader.loglevel",
+    prefix: "ESEDBReader",
+  };
+  return new ConsoleAPI(consoleOptions);
+});
+
+// We have a globally unique identifier for ESE instances. A new one
+// is used for each different database opened.
+let gESEInstanceCounter = 0;
+
+// We limit the length of strings that we read from databases.
+const MAX_STR_LENGTH = 64 * 1024;
+
+// Kernel-related types:
+export const KERNEL = {};
+
+KERNEL.FILETIME = new ctypes.StructType("FILETIME", [
+  { dwLowDateTime: ctypes.uint32_t },
+  { dwHighDateTime: ctypes.uint32_t },
+]);
+KERNEL.SYSTEMTIME = new ctypes.StructType("SYSTEMTIME", [
+  { wYear: ctypes.uint16_t },
+  { wMonth: ctypes.uint16_t },
+  { wDayOfWeek: ctypes.uint16_t },
+  { wDay: ctypes.uint16_t },
+  { wHour: ctypes.uint16_t },
+  { wMinute: ctypes.uint16_t },
+  { wSecond: ctypes.uint16_t },
+  { wMilliseconds: ctypes.uint16_t },
+]);
+
+// DB column types, cribbed from the ESE header
+export var COLUMN_TYPES = {
+  JET_coltypBit: 1 /* True, False, or NULL */,
+  JET_coltypUnsignedByte: 2 /* 1-byte integer, unsigned */,
+  JET_coltypShort: 3 /* 2-byte integer, signed */,
+  JET_coltypLong: 4 /* 4-byte integer, signed */,
+  JET_coltypCurrency: 5 /* 8 byte integer, signed */,
+  JET_coltypIEEESingle: 6 /* 4-byte IEEE single precision */,
+  JET_coltypIEEEDouble: 7 /* 8-byte IEEE double precision */,
+  JET_coltypDateTime: 8 /* Integral date, fractional time */,
+  JET_coltypBinary: 9 /* Binary data, < 255 bytes */,
+  JET_coltypText: 10 /* ANSI text, case insensitive, < 255 bytes */,
+  JET_coltypLongBinary: 11 /* Binary data, long value */,
+  JET_coltypLongText: 12 /* ANSI text, long value */,
+
+  JET_coltypUnsignedLong: 14 /* 4-byte unsigned integer */,
+  JET_coltypLongLong: 15 /* 8-byte signed integer */,
+  JET_coltypGUID: 16 /* 16-byte globally unique identifier */,
+};
+
+// Not very efficient, but only used for error messages
+function getColTypeName(numericValue) {
+  return (
+    Object.keys(COLUMN_TYPES).find(t => COLUMN_TYPES[t] == numericValue) ||
+    "unknown"
+  );
+}
+
+// All type constants and method wrappers go on this object:
+export const ESE = {};
+
+ESE.JET_ERR = ctypes.long;
+ESE.JET_PCWSTR = ctypes.char16_t.ptr;
+// The ESE header calls this JET_API_PTR, but because it isn't ever used as a
+// pointer, I opted for a different name.
+// Note that this is defined differently on 32 vs. 64-bit in the header.
+ESE.JET_API_ITEM =
+  ctypes.voidptr_t.size == 4 ? ctypes.unsigned_long : ctypes.uint64_t;
+ESE.JET_INSTANCE = ESE.JET_API_ITEM;
+ESE.JET_SESID = ESE.JET_API_ITEM;
+ESE.JET_TABLEID = ESE.JET_API_ITEM;
+ESE.JET_COLUMNID = ctypes.unsigned_long;
+ESE.JET_GRBIT = ctypes.unsigned_long;
+ESE.JET_COLTYP = ctypes.unsigned_long;
+ESE.JET_DBID = ctypes.unsigned_long;
+
+ESE.JET_COLUMNDEF = new ctypes.StructType("JET_COLUMNDEF", [
+  { cbStruct: ctypes.unsigned_long },
+  { columnid: ESE.JET_COLUMNID },
+  { coltyp: ESE.JET_COLTYP },
+  { wCountry: ctypes.unsigned_short }, // sepcifies the country/region for the column definition
+  { langid: ctypes.unsigned_short },
+  { cp: ctypes.unsigned_short },
+  { wCollate: ctypes.unsigned_short } /* Must be 0 */,
+  { cbMax: ctypes.unsigned_long },
+  { grbit: ESE.JET_GRBIT },
+]);
+
+// Track open databases
+let gOpenDBs = new Map();
+
+// Track open libraries
+export let gLibs = {};
+
+function convertESEError(errorCode) {
+  switch (errorCode) {
+    case -1213 /* JET_errPageSizeMismatch */:
+    case -1002 /* JET_errInvalidName*/:
+    case -1507 /* JET_errColumnNotFound */:
+      // The DB format has changed and we haven't updated this migration code:
+      return "The database format has changed, error code: " + errorCode;
+    case -1032 /* JET_errFileAccessDenied */:
+    case -1207 /* JET_errDatabaseLocked */:
+    case -1302 /* JET_errTableLocked */:
+      return "The database or table is locked, error code: " + errorCode;
+    case -1305 /* JET_errObjectNotFound */:
+      return "The table/object was not found.";
+    case -1809 /* JET_errPermissionDenied*/:
+    case -1907 /* JET_errAccessDenied */:
+      return "Access or permission denied, error code: " + errorCode;
+    case -1044 /* JET_errInvalidFilename */:
+      return "Invalid file name";
+    case -1811 /* JET_errFileNotFound */:
+      return "File not found";
+    case -550 /* JET_errDatabaseDirtyShutdown */:
+      return "Database in dirty shutdown state (without the requisite logs?)";
+    case -514 /* JET_errBadLogVersion */:
+      return "Database log version does not match the version of ESE in use.";
+    default:
+      return "Unknown error: " + errorCode;
+  }
+}
+
+function handleESEError(
+  method,
+  methodName,
+  shouldThrow = true,
+  errorLog = true
+) {
+  return function () {
+    let rv;
+    try {
+      rv = method.apply(null, arguments);
+    } catch (ex) {
+      lazy.log.error("Error calling into ctypes method", methodName, ex);
+      throw ex;
+    }
+    let resultCode = parseInt(rv.toString(10), 10);
+    if (resultCode < 0) {
+      if (errorLog) {
+        lazy.log.error("Got error " + resultCode + " calling " + methodName);
+      }
+      if (shouldThrow) {
+        throw new Error(convertESEError(rv));
+      }
+    } else if (resultCode > 0 && errorLog) {
+      lazy.log.warn("Got warning " + resultCode + " calling " + methodName);
+    }
+    return resultCode;
+  };
+}
+
+export function declareESEFunction(methodName, ...args) {
+  let declaration = ["Jet" + methodName, ctypes.winapi_abi, ESE.JET_ERR].concat(
+    args
+  );
+  let ctypeMethod = gLibs.ese.declare.apply(gLibs.ese, declaration);
+  ESE[methodName] = handleESEError(ctypeMethod, methodName);
+  ESE["FailSafe" + methodName] = handleESEError(ctypeMethod, methodName, false);
+  ESE["Manual" + methodName] = handleESEError(
+    ctypeMethod,
+    methodName,
+    false,
+    false
+  );
+}
+
+function declareESEFunctions() {
+  declareESEFunction(
+    "GetDatabaseFileInfoW",
+    ESE.JET_PCWSTR,
+    ctypes.voidptr_t,
+    ctypes.unsigned_long,
+    ctypes.unsigned_long
+  );
+
+  declareESEFunction(
+    "GetSystemParameterW",
+    ESE.JET_INSTANCE,
+    ESE.JET_SESID,
+    ctypes.unsigned_long,
+    ESE.JET_API_ITEM.ptr,
+    ESE.JET_PCWSTR,
+    ctypes.unsigned_long
+  );
+  declareESEFunction(
+    "SetSystemParameterW",
+    ESE.JET_INSTANCE.ptr,
+    ESE.JET_SESID,
+    ctypes.unsigned_long,
+    ESE.JET_API_ITEM,
+    ESE.JET_PCWSTR
+  );
+  declareESEFunction("CreateInstanceW", ESE.JET_INSTANCE.ptr, ESE.JET_PCWSTR);
+  declareESEFunction("Init", ESE.JET_INSTANCE.ptr);
+
+  declareESEFunction(
+    "BeginSessionW",
+    ESE.JET_INSTANCE,
+    ESE.JET_SESID.ptr,
+    ESE.JET_PCWSTR,
+    ESE.JET_PCWSTR
+  );
+  declareESEFunction(
+    "AttachDatabaseW",
+    ESE.JET_SESID,
+    ESE.JET_PCWSTR,
+    ESE.JET_GRBIT
+  );
+  declareESEFunction("DetachDatabaseW", ESE.JET_SESID, ESE.JET_PCWSTR);
+  declareESEFunction(
+    "OpenDatabaseW",
+    ESE.JET_SESID,
+    ESE.JET_PCWSTR,
+    ESE.JET_PCWSTR,
+    ESE.JET_DBID.ptr,
+    ESE.JET_GRBIT
+  );
+  declareESEFunction(
+    "OpenTableW",
+    ESE.JET_SESID,
+    ESE.JET_DBID,
+    ESE.JET_PCWSTR,
+    ctypes.voidptr_t,
+    ctypes.unsigned_long,
+    ESE.JET_GRBIT,
+    ESE.JET_TABLEID.ptr
+  );
+
+  declareESEFunction(
+    "GetColumnInfoW",
+    ESE.JET_SESID,
+    ESE.JET_DBID,
+    ESE.JET_PCWSTR,
+    ESE.JET_PCWSTR,
+    ctypes.voidptr_t,
+    ctypes.unsigned_long,
+    ctypes.unsigned_long
+  );
+
+  declareESEFunction(
+    "Move",
+    ESE.JET_SESID,
+    ESE.JET_TABLEID,
+    ctypes.long,
+    ESE.JET_GRBIT
+  );
+
+  declareESEFunction(
+    "RetrieveColumn",
+    ESE.JET_SESID,
+    ESE.JET_TABLEID,
+    ESE.JET_COLUMNID,
+    ctypes.voidptr_t,
+    ctypes.unsigned_long,
+    ctypes.unsigned_long.ptr,
+    ESE.JET_GRBIT,
+    ctypes.voidptr_t
+  );
+
+  declareESEFunction("CloseTable", ESE.JET_SESID, ESE.JET_TABLEID);
+  declareESEFunction(
+    "CloseDatabase",
+    ESE.JET_SESID,
+    ESE.JET_DBID,
+    ESE.JET_GRBIT
+  );
+
+  declareESEFunction("EndSession", ESE.JET_SESID, ESE.JET_GRBIT);
+
+  declareESEFunction("Term", ESE.JET_INSTANCE);
+}
+
+function unloadLibraries() {
+  lazy.log.debug("Unloading");
+  if (gOpenDBs.size) {
+    lazy.log.error("Shouldn't unload libraries before DBs are closed!");
+    for (let db of gOpenDBs.values()) {
+      db._close();
+    }
+  }
+  for (let k of Object.keys(ESE)) {
+    delete ESE[k];
+  }
+  gLibs.ese.close();
+  gLibs.kernel.close();
+  delete gLibs.ese;
+  delete gLibs.kernel;
+}
+
+export function loadLibraries() {
+  Services.obs.addObserver(unloadLibraries, "xpcom-shutdown");
+  gLibs.ese = ctypes.open("esent.dll");
+  gLibs.kernel = ctypes.open("kernel32.dll");
+  KERNEL.FileTimeToSystemTime = gLibs.kernel.declare(
+    "FileTimeToSystemTime",
+    ctypes.winapi_abi,
+    ctypes.int,
+    KERNEL.FILETIME.ptr,
+    KERNEL.SYSTEMTIME.ptr
+  );
+
+  declareESEFunctions();
+}
+
+function ESEDB(rootPath, dbPath, logPath) {
+  lazy.log.info("Created db");
+  this.rootPath = rootPath;
+  this.dbPath = dbPath;
+  this.logPath = logPath;
+  this._references = 0;
+  this._init();
+}
+
+ESEDB.prototype = {
+  rootPath: null,
+  dbPath: null,
+  logPath: null,
+  _opened: false,
+  _attached: false,
+  _sessionCreated: false,
+  _instanceCreated: false,
+  _dbId: null,
+  _sessionId: null,
+  _instanceId: null,
+
+  _init() {
+    if (!gLibs.ese) {
+      loadLibraries();
+    }
+    this.incrementReferenceCounter();
+    this._internalOpen();
+  },
+
+  _internalOpen() {
+    try {
+      let dbinfo = new ctypes.unsigned_long();
+      ESE.GetDatabaseFileInfoW(
+        this.dbPath,
+        dbinfo.address(),
+        ctypes.unsigned_long.size,
+        17
+      );
+
+      let pageSize = ctypes.UInt64.lo(dbinfo.value);
+      ESE.SetSystemParameterW(
+        null,
+        0,
+        64 /* JET_paramDatabasePageSize*/,
+        pageSize,
+        null
+      );
+
+      this._instanceId = new ESE.JET_INSTANCE();
+      ESE.CreateInstanceW(
+        this._instanceId.address(),
+        "firefox-dbreader-" + gESEInstanceCounter++
+      );
+      this._instanceCreated = true;
+
+      ESE.SetSystemParameterW(
+        this._instanceId.address(),
+        0,
+        0 /* JET_paramSystemPath*/,
+        0,
+        this.rootPath
+      );
+      ESE.SetSystemParameterW(
+        this._instanceId.address(),
+        0,
+        1 /* JET_paramTempPath */,
+        0,
+        this.rootPath
+      );
+      ESE.SetSystemParameterW(
+        this._instanceId.address(),
+        0,
+        2 /* JET_paramLogFilePath*/,
+        0,
+        this.logPath
+      );
+
+      // Shouldn't try to call JetTerm if the following call fails.
+      this._instanceCreated = false;
+      ESE.Init(this._instanceId.address());
+      this._instanceCreated = true;
+      this._sessionId = new ESE.JET_SESID();
+      ESE.BeginSessionW(
+        this._instanceId,
+        this._sessionId.address(),
+        null,
+        null
+      );
+      this._sessionCreated = true;
+
+      const JET_bitDbReadOnly = 1;
+      ESE.AttachDatabaseW(this._sessionId, this.dbPath, JET_bitDbReadOnly);
+      this._attached = true;
+      this._dbId = new ESE.JET_DBID();
+      ESE.OpenDatabaseW(
+        this._sessionId,
+        this.dbPath,
+        null,
+        this._dbId.address(),
+        JET_bitDbReadOnly
+      );
+      this._opened = true;
+    } catch (ex) {
+      try {
+        this._close();
+      } catch (innerException) {
+        console.error(innerException);
+      }
+      // Make sure caller knows we failed.
+      throw ex;
+    }
+    gOpenDBs.set(this.dbPath, this);
+  },
+
+  checkForColumn(tableName, columnName) {
+    if (!this._opened) {
+      throw new Error("The database was closed!");
+    }
+
+    let columnInfo;
+    try {
+      columnInfo = this._getColumnInfo(tableName, [{ name: columnName }]);
+    } catch (ex) {
+      return null;
+    }
+    return columnInfo[0];
+  },
+
+  tableExists(tableName) {
+    if (!this._opened) {
+      throw new Error("The database was closed!");
+    }
+
+    let tableId = new ESE.JET_TABLEID();
+    let rv = ESE.ManualOpenTableW(
+      this._sessionId,
+      this._dbId,
+      tableName,
+      null,
+      0,
+      4 /* JET_bitTableReadOnly */,
+      tableId.address()
+    );
+    if (rv == -1305 /* JET_errObjectNotFound */) {
+      return false;
+    }
+    if (rv < 0) {
+      lazy.log.error("Got error " + rv + " calling OpenTableW");
+      throw new Error(convertESEError(rv));
+    }
+
+    if (rv > 0) {
+      lazy.log.error("Got warning " + rv + " calling OpenTableW");
+    }
+    ESE.FailSafeCloseTable(this._sessionId, tableId);
+    return true;
+  },
+
+  *tableItems(tableName, columns) {
+    if (!this._opened) {
+      throw new Error("The database was closed!");
+    }
+
+    let tableOpened = false;
+    let tableId;
+    try {
+      tableId = this._openTable(tableName);
+      tableOpened = true;
+
+      let columnInfo = this._getColumnInfo(tableName, columns);
+
+      let rv = ESE.ManualMove(
+        this._sessionId,
+        tableId,
+        -2147483648 /* JET_MoveFirst */,
+        0
+      );
+      if (rv == -1603 /* JET_errNoCurrentRecord */) {
+        // There are no rows in the table.
+        this._closeTable(tableId);
+        return;
+      }
+      if (rv != 0) {
+        throw new Error(convertESEError(rv));
+      }
+
+      do {
+        let rowContents = {};
+        for (let column of columnInfo) {
+          let [buffer, bufferSize] = this._getBufferForColumn(column);
+          // We handle errors manually so we accurately deal with NULL values.
+          let err = ESE.ManualRetrieveColumn(
+            this._sessionId,
+            tableId,
+            column.id,
+            buffer.address(),
+            bufferSize,
+            null,
+            0,
+            null
+          );
+          rowContents[column.name] = this._convertResult(column, buffer, err);
+        }
+        yield rowContents;
+      } while (
+        ESE.ManualMove(this._sessionId, tableId, 1 /* JET_MoveNext */, 0) === 0
+      );
+    } catch (ex) {
+      if (tableOpened) {
+        this._closeTable(tableId);
+      }
+      throw ex;
+    }
+    this._closeTable(tableId);
+  },
+
+  _openTable(tableName) {
+    let tableId = new ESE.JET_TABLEID();
+    ESE.OpenTableW(
+      this._sessionId,
+      this._dbId,
+      tableName,
+      null,
+      0,
+      4 /* JET_bitTableReadOnly */,
+      tableId.address()
+    );
+    return tableId;
+  },
+
+  _getBufferForColumn(column) {
+    let buffer;
+    if (column.type == "string") {
+      let wchar_tArray = ctypes.ArrayType(ctypes.char16_t);
+      // size on the column is in bytes, 2 bytes to a wchar, so:
+      let charCount = column.dbSize >> 1;
+      buffer = new wchar_tArray(charCount);
+    } else if (column.type == "boolean") {
+      buffer = new ctypes.uint8_t();
+    } else if (column.type == "date") {
+      buffer = new KERNEL.FILETIME();
+    } else if (column.type == "guid") {
+      let byteArray = ctypes.ArrayType(ctypes.uint8_t);
+      buffer = new byteArray(column.dbSize);
+    } else {
+      throw new Error("Unknown type " + column.type);
+    }
+    return [buffer, buffer.constructor.size];
+  },
+
+  _convertResult(column, buffer, err) {
+    if (err != 0) {
+      if (err == 1004) {
+        // Deal with null values:
+        buffer = null;
+      } else {
+        console.error(
+          "Unexpected JET error: ",
+          err,
+          "; retrieving value for column ",
+          column.name
+        );
+        throw new Error(convertESEError(err));
+      }
+    }
+    if (column.type == "string") {
+      return buffer ? buffer.readString() : "";
+    }
+    if (column.type == "boolean") {
+      return buffer ? buffer.value == 255 : false;
+    }
+    if (column.type == "guid") {
+      if (buffer.length != 16) {
+        console.error(
+          "Buffer size for guid field ",
+          column.id,
+          " should have been 16!"
+        );
+        return "";
+      }
+      let rv = "{";
+      for (let i = 0; i < 16; i++) {
+        if (i == 4 || i == 6 || i == 8 || i == 10) {
+          rv += "-";
+        }
+        let byteValue = buffer.addressOfElement(i).contents;
+        // Ensure there's a leading 0
+        rv += ("0" + byteValue.toString(16)).substr(-2);
+      }
+      return rv + "}";
+    }
+    if (column.type == "date") {
+      if (!buffer) {
+        return null;
+      }
+      let systemTime = new KERNEL.SYSTEMTIME();
+      let result = KERNEL.FileTimeToSystemTime(
+        buffer.address(),
+        systemTime.address()
+      );
+      if (result == 0) {
+        throw new Error(ctypes.winLastError);
+      }
+
+      // System time is in UTC, so we use Date.UTC to get milliseconds from epoch,
+      // then divide by 1000 to get seconds, and round down:
+      return new Date(
+        Date.UTC(
+          systemTime.wYear,
+          systemTime.wMonth - 1,
+          systemTime.wDay,
+          systemTime.wHour,
+          systemTime.wMinute,
+          systemTime.wSecond,
+          systemTime.wMilliseconds
+        )
+      );
+    }
+    return undefined;
+  },
+
+  _getColumnInfo(tableName, columns) {
+    let rv = [];
+    for (let column of columns) {
+      let columnInfoFromDB = new ESE.JET_COLUMNDEF();
+      ESE.GetColumnInfoW(
+        this._sessionId,
+        this._dbId,
+        tableName,
+        column.name,
+        columnInfoFromDB.address(),
+        ESE.JET_COLUMNDEF.size,
+        0 /* JET_ColInfo */
+      );
+      let dbType = parseInt(columnInfoFromDB.coltyp.toString(10), 10);
+      let dbSize = parseInt(columnInfoFromDB.cbMax.toString(10), 10);
+      if (column.type == "string") {
+        if (
+          dbType != COLUMN_TYPES.JET_coltypLongText &&
+          dbType != COLUMN_TYPES.JET_coltypText
+        ) {
+          throw new Error(
+            "Invalid column type for column " +
+              column.name +
+              "; expected text type, got type " +
+              getColTypeName(dbType)
+          );
+        }
+        if (dbSize > MAX_STR_LENGTH) {
+          throw new Error(
+            "Column " +
+              column.name +
+              " has more than 64k data in it. This API is not designed to handle data that large."
+          );
+        }
+      } else if (column.type == "boolean") {
+        if (dbType != COLUMN_TYPES.JET_coltypBit) {
+          throw new Error(
+            "Invalid column type for column " +
+              column.name +
+              "; expected bit type, got type " +
+              getColTypeName(dbType)
+          );
+        }
+      } else if (column.type == "date") {
+        if (dbType != COLUMN_TYPES.JET_coltypLongLong) {
+          throw new Error(
+            "Invalid column type for column " +
+              column.name +
+              "; expected long long type, got type " +
+              getColTypeName(dbType)
+          );
+        }
+      } else if (column.type == "guid") {
+        if (dbType != COLUMN_TYPES.JET_coltypGUID) {
+          throw new Error(
+            "Invalid column type for column " +
+              column.name +
+              "; expected guid type, got type " +
+              getColTypeName(dbType)
+          );
+        }
+      } else if (column.type) {
+        throw new Error(
+          "Unknown column type " +
+            column.type +
+            " requested for column " +
+            column.name +
+            ", don't know what to do."
+        );
+      }
+
+      rv.push({
+        name: column.name,
+        id: columnInfoFromDB.columnid,
+        type: column.type,
+        dbSize,
+        dbType,
+      });
+    }
+    return rv;
+  },
+
+  _closeTable(tableId) {
+    ESE.FailSafeCloseTable(this._sessionId, tableId);
+  },
+
+  _close() {
+    this._internalClose();
+    gOpenDBs.delete(this.dbPath);
+  },
+
+  _internalClose() {
+    if (this._opened) {
+      lazy.log.debug("close db");
+      ESE.FailSafeCloseDatabase(this._sessionId, this._dbId, 0);
+      lazy.log.debug("finished close db");
+      this._opened = false;
+    }
+    if (this._attached) {
+      lazy.log.debug("detach db");
+      ESE.FailSafeDetachDatabaseW(this._sessionId, this.dbPath);
+      this._attached = false;
+    }
+    if (this._sessionCreated) {
+      lazy.log.debug("end session");
+      ESE.FailSafeEndSession(this._sessionId, 0);
+      this._sessionCreated = false;
+    }
+    if (this._instanceCreated) {
+      lazy.log.debug("term");
+      ESE.FailSafeTerm(this._instanceId);
+      this._instanceCreated = false;
+    }
+  },
+
+  incrementReferenceCounter() {
+    this._references++;
+  },
+
+  decrementReferenceCounter() {
+    this._references--;
+    if (this._references <= 0) {
+      this._close();
+    }
+  },
+};
+
+export let ESEDBReader = {
+  openDB(rootDir, dbFile, logDir) {
+    let dbFilePath = dbFile.path;
+    if (gOpenDBs.has(dbFilePath)) {
+      let db = gOpenDBs.get(dbFilePath);
+      db.incrementReferenceCounter();
+      return db;
+    }
+    // ESE is really picky about the trailing slashes according to the docs,
+    // so we do as we're told and ensure those are there:
+    return new ESEDB(rootDir.path + "\\", dbFilePath, logDir.path + "\\");
+  },
+
+  async dbLocked(dbFile) {
+    const utils = Cc[
+      "@mozilla.org/profile/migrator/edgemigrationutils;1"
+    ].createInstance(Ci.nsIEdgeMigrationUtils);
+
+    const locked = await utils.isDbLocked(dbFile);
+
+    if (locked) {
+      console.error(`ESE DB at ${dbFile.path} is locked.`);
+    }
+
+    return locked;
+  },
+
+  closeDB(db) {
+    db.decrementReferenceCounter();
+  },
+
+  COLUMN_TYPES,
+};