Merge pull request #46 from mapbox/null-tile

Detect null or non-buffer tile

lib/mbtiles.js

@@ -154,6 +154,10 @@ MBTiles.prototype.getTile = function(z, x, y, callback) {
             return callback(new Error('Tile does not exist'));
         } else if (err) {
             return callback(err);
+        } else if (!row.tile_data || !Buffer.isBuffer(row.tile_data)) {
+            var err = new Error('Tile is invalid');
+            err.code = 'EINVALIDTILE';
+            return callback(err);
         } else {
             var headers = tiletype.headers(row.tile_data);
             headers['Last-Modified'] = new Date(mbtiles._stat.mtime).toUTCString();

test/read.test.js

@@ -10,7 +10,8 @@ var fixtures = {
     plain_3: __dirname + '/fixtures/plain_3.mbtiles',
     plain_4: __dirname + '/fixtures/plain_4.mbtiles',
     non_existent: __dirname + '/fixtures/non_existent.mbtiles',
-    corrupt: __dirname + '/fixtures/corrupt.mbtiles'
+    corrupt: __dirname + '/fixtures/corrupt.mbtiles',
+    corrupt_null_tile: __dirname + '/fixtures/corrupt_null_tile.mbtiles'
 };
 
 function yieldsError(assert, error, msg, callback) {
@@ -140,3 +141,6 @@ fs.readdirSync(__dirname + '/fixtures/grids/').forEach(function(file) {
     });
 });
 
+tape('corrupt null tile', function(assert) {
+    loaded.corrupt_null_tile.getTile(1, 0, 1, yieldsError(assert, 'error', 'Tile is invalid', assert.end));
+});