feat: implement ole columns

src/data.ts

@@ -41,6 +41,8 @@ export function readFieldValue(
             return readCurrency(buffer);
         case "memo":
             return readMemo(buffer, db);
+        case "ole":
+            return readOLE(buffer, db);
         default:
             return `Column type ${column.type} is currently not supported`;
     }
@@ -145,3 +147,49 @@ function readMemo(buffer: Buffer, db: Database): string {
         throw new Error(`Unknown memo type ${bitmask}`);
     }
 }
+
+/**
+ * @see https://github.com/brianb/mdbtools/blob/d6f5745d949f37db969d5f424e69b54f0da60b9b/src/libmdb/data.c#L626-L688
+ */
+function readOLE(buffer: Buffer, db: Database): Buffer {
+    const memoLength = buffer.readUIntLE(0, 3);
+
+    const bitmask = buffer.readUInt8(3);
+
+    if (bitmask & 0x80) {
+        // inline
+        return buffer.slice(12, 12 + memoLength);
+    } else if (bitmask & 0x40) {
+        // single page
+        const pageRow = buffer.readUInt32LE(4);
+        const rowBuffer = db.findPageRow(pageRow);
+        return rowBuffer.slice(0, memoLength);
+    } else if (bitmask === 0) {
+        // multi page
+        let pageRow = buffer.readInt32LE(4);
+
+        let memoDataBuffer = Buffer.alloc(0);
+        do {
+            const rowBuffer = db.findPageRow(pageRow);
+
+            if (memoDataBuffer.length + rowBuffer.length - 4 > memoLength) {
+                break;
+            }
+
+            if (rowBuffer.length === 0) {
+                break;
+            }
+
+            memoDataBuffer = Buffer.concat([
+                memoDataBuffer,
+                rowBuffer.slice(4, buffer.length),
+            ]);
+
+            pageRow = rowBuffer.readUInt32LE(0);
+        } while (pageRow !== 0);
+
+        return memoDataBuffer.slice(0, memoLength);
+    } else {
+        throw new Error(`Unknown memo type ${bitmask}`);
+    }
+}

test/ole.spec.ts

@@ -0,0 +1,17 @@
+import { readFileSync } from "fs";
+import MDBReader, { Table } from "../src";
+import { resolve } from "path";
+
+let table: Table;
+
+beforeEach(() => {
+    const path = resolve(__dirname, "data", "V2007", "ole.accdb");
+    const buffer = readFileSync(path);
+    const reader = new MDBReader(buffer);
+    table = reader.getTable("Table1");
+});
+
+it("reads ole data ", () => {
+    const rows = table.getData();
+    // TODO: check for correct values
+});