Merge pull request stephencelis#562 from stephencelis/issue-561

Issue 561

Author: jberkel

CHANGELOG.md

@@ -2,6 +2,7 @@
 ========================================
 
 * Fixed SQLCipher integration with read-only databases ([#559][])
+* Fixed null pointer when fetching an empty BLOB ([#561][])
 
 0.11.1 (06-12-2016), [diff][diff-0.11.1]
 ========================================
@@ -25,3 +26,4 @@
 [#546]: https://github.com/stephencelis/SQLite.swift/issues/546
 [#553]: https://github.com/stephencelis/SQLite.swift/pull/553
 [#559]: https://github.com/stephencelis/SQLite.swift/pull/559
+[#561]: https://github.com/stephencelis/SQLite.swift/issues/561

SQLite/Core/Statement.swift

@@ -244,7 +244,9 @@ public struct Cursor {
             let length = Int(sqlite3_column_bytes(handle, Int32(idx)))
             return Blob(bytes: pointer, length: length)
         } else {
-            fatalError("sqlite3_column_blob returned NULL")
+            // The return value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
+            // https://www.sqlite.org/c3ref/column_blob.html
+            return Blob(bytes: [])
         }
     }
 

SQLiteTests/StatementTests.swift

@@ -14,4 +14,13 @@ class StatementTests : SQLiteTestCase {
         let blob = statement.row[0] as Blob
         XCTAssertEqual("[email protected]", String(bytes: blob.bytes, encoding: .utf8)!)
     }
+
+    func test_zero_sized_blob_returns_null() {
+        let blobs = Table("blobs")
+        let blobColumn = Expression<Blob>("blob_column")
+        try! db.run(blobs.create { $0.column(blobColumn) })
+        try! db.run(blobs.insert(blobColumn <- Blob(bytes: [])))
+        let blobValue = try! db.scalar(blobs.select(blobColumn).limit(1, offset: 0))
+        XCTAssertEqual([], blobValue.bytes)
+    }
 }