Support binding an empty ByteArray to a BLOB

If you try to bind an empty ByteArray it will crash because
ByteArray.refTo(0) cannot find an element at index 0. The solution is to
explicitly handle when the ByteArray is empty and to make an empty BLOB.

Author: conradev

sqliter-driver/src/nativeCommonMain/kotlin/co/touchlab/sqliter/interop/ActualSqliteStatement.kt

@@ -25,10 +25,10 @@ internal class ActualSqliteStatement(private val db: SqliteDatabase, private val
 
     override fun columnGetBlob(columnIndex: Int): ByteArray {
         val blobSize = sqlite3_column_bytes(stmtPointer, columnIndex)
-        val blob = sqlite3_column_blob(stmtPointer, columnIndex)
+        if (blobSize == 0) return byteArrayOf()
 
-        if (blobSize < 0 || blob == null)
-            throw sqlException(db.logger, db.config, "Byte array size/type issue col $columnIndex")
+        val blob = sqlite3_column_blob(stmtPointer, columnIndex)
+            ?: throw sqlException(db.logger, db.config, "Byte array size/type issue col $columnIndex")
 
         return blob.readBytes(blobSize)
     }
@@ -123,7 +123,8 @@ internal class ActualSqliteStatement(private val db: SqliteDatabase, private val
     }
 
     override fun bindBlob(index: Int, value: ByteArray) = opResult(db) {
-        sqlite3_bind_blob(stmtPointer, index, value.refTo(0), value.size, SQLITE_TRANSIENT)
+        if (value.isNotEmpty()) sqlite3_bind_blob(stmtPointer, index, value.refTo(0), value.size, SQLITE_TRANSIENT)
+        else sqlite3_bind_zeroblob(stmtPointer, index, 0)
     }
 
     private inline fun opResult(db: SqliteDatabase, block: () -> Int) {

sqliter-driver/src/nativeCommonTest/kotlin/co/touchlab/sqliter/NativeStatementTest.kt

@@ -218,33 +218,33 @@ class NativeStatementTest : BaseDatabaseTest(){
         }
     }
 
-    val TWO_COL_WITH_BLOB = "CREATE TABLE test (num INTEGER NOT NULL, " +
-            "blb BLOB NOT NULL)"
+    val THREE_COL_WITH_BLOB = "CREATE TABLE test (num INTEGER NOT NULL, " +
+            "blb BLOB NOT NULL, null_blb BLOB)"
 
-//    @Test
-    // Need to review what other drivers do here. It's not acting as expected
-    // https://github.com/touchlab/SQLiter/issues/62
+    @Test
     fun bindEmptyBlob() {
-        basicTestDb(TWO_COL_WITH_BLOB) {
+        basicTestDb(THREE_COL_WITH_BLOB) {
             it.withConnection {
-                it.withStatement("insert into test(num, blb)values(?,?)") {
+                it.withStatement("insert into test(num, blb, null_blb)values(?,?,?)") {
                     bindLong(1, 22)
-                    bindBlob(2, ByteArray(0){it.toByte()})
+                    bindBlob(2, byteArrayOf())
+                    bindBlob(3, null)
                     executeInsert()
                 }
 
-                it.withStatement("select blb from test") {
+                it.withStatement("select blb, null_blb from test") {
                     val query = query()
                     query.next()
                     assertEquals(query.getBytes(query.columnNames["blb"]!!).size, 0)
+                    assertEquals(query.getBytesOrNull(query.columnNames["null_blb"]!!), null)
                 }
             }
         }
     }
 
     @Test
     fun bindBlob() {
-        basicTestDb(TWO_COL_WITH_BLOB) {
+        basicTestDb(THREE_COL_WITH_BLOB) {
             it.withConnection {
                 it.withTransaction {
                     it.withStatement("insert into test(num, blb)values(?,?)") {