Regression test for large string joins.

test/cctest/test-strings.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 
 // Check that we can traverse very deep stacks of ConsStrings using
 // StringInputBuffer.  Check that Get(int) works on very deep stacks
 // of ConsStrings.  These operations may not be very fast, but they
 // should be possible without getting errors due to too deep recursion.
 
 #include <stdlib.h>
 
 #include "v8.h"
@@ skipping 569 matching lines @@
   CHECK(SlicedString::cast(*string)->parent()->IsSeqString());
   CHECK_EQ("bcdefghijklmnopqrstuvwxy", *(string->ToCString()));
 
   result = CompileRun(slice_from_slice);
   CHECK(result->IsString());
   string = v8::Utils::OpenHandle(v8::String::Cast(*result));
   CHECK(string->IsSlicedString());
   CHECK(SlicedString::cast(*string)->parent()->IsSeqString());
   CHECK_EQ("cdefghijklmnopqrstuvwx", *(string->ToCString()));
 }
+
+
+// string s is made of 2^17 = 131072 'c' characters.
+// a is an array starting with 'bad', followed by 2^14 times the string s.
+// That means the total length of the concatenated strings is 2^31 + 3.
+// So on 32bits systems summing the lengths of the strings (as smis) overflows
+// and wraps.
+static const char* join_causing_out_of_memory =
+    "var two_14 = Math.pow(2, 14);"
+    "var two_17 = Math.pow(2, 17);"
+    "var s = Array(two_17 + 1).join('c');"
+    "var a = ['bad'];"
+    "for (var i = 1; i <= two_14; i++) a.push(s);"
+    "a.join("");";
+
+
+TEST(AsciiArrayJoin) {
+  // Set heap limits.
+  static const int K = 1024;
+  v8::ResourceConstraints constraints;
+  constraints.set_max_young_space_size(256 * K);
+  constraints.set_max_old_space_size(4 * K * K);
+  v8::SetResourceConstraints(&constraints);
+
+  v8::HandleScope scope;
+  LocalContext context;
+  v8::V8::IgnoreOutOfMemoryException();
+  v8::Local<v8::Script> script =
+      v8::Script::Compile(v8::String::New(join_causing_out_of_memory));
+  v8::Local<v8::Value> result = script->Run();
+
+  // Check for out of memory state.
+  CHECK(result.IsEmpty());
+  CHECK(context->HasOutOfMemoryException());
+}