Limit XFA FormCalc program translation size.

BUG=chromium:665087,chromium:718492

Change-Id: I09e93b4167ab2c0b3b53641243aa0cbeb5b98c4f
Reviewed-on: https://pdfium-review.googlesource.com/3114
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Nicolás Peña <npm@chromium.org>

1 files changed, 204 insertions, 119 deletions

diff --git a/xfa/fxfa/fm2js/xfa_expression.cpp b/xfa/fxfa/fm2js/xfa_expression.cpp
index c1e451eade..324038f7ed 100644
--- a/xfa/fxfa/fm2js/xfa_expression.cpp
+++ b/xfa/fxfa/fm2js/xfa_expression.cpp
@@ -18,6 +18,11 @@ const wchar_t RUNTIMEBLOCKTEMPARRAY[] =
 const wchar_t RUNTIMEBLOCKTEMPARRAYINDEX[] =
     L"foxit_xfa_formcalc_runtime_block_temp_array_index";
 
+const wchar_t kLessEqual[] = L" <= ";
+const wchar_t kGreaterEqual[] = L" >= ";
+const wchar_t kPlusEqual[] = L" += ";
+const wchar_t kMinusEqual[] = L" -= ";
+
 }  // namespace
 
 CXFA_FMExpression::CXFA_FMExpression(uint32_t line)
@@ -26,9 +31,13 @@ CXFA_FMExpression::CXFA_FMExpression(uint32_t line)
 CXFA_FMExpression::CXFA_FMExpression(uint32_t line, XFA_FM_EXPTYPE type)
     : m_type(type), m_line(line) {}
 
-void CXFA_FMExpression::ToJavaScript(CFX_WideTextBuf& javascript) {}
+bool CXFA_FMExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+  return true;
+}
 
-void CXFA_FMExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {}
+bool CXFA_FMExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+  return true;
+}
 
 CXFA_FMFunctionDefinition::CXFA_FMFunctionDefinition(
     uint32_t line,
@@ -44,10 +53,10 @@ CXFA_FMFunctionDefinition::CXFA_FMFunctionDefinition(
 
 CXFA_FMFunctionDefinition::~CXFA_FMFunctionDefinition() {}
 
-void CXFA_FMFunctionDefinition::ToJavaScript(CFX_WideTextBuf& javascript) {
+bool CXFA_FMFunctionDefinition::ToJavaScript(CFX_WideTextBuf& javascript) {
   if (m_isGlobal && m_pExpressions.empty()) {
     javascript << L"// comments only";
-    return;
+    return true;
   }
   if (m_isGlobal) {
     javascript << L"(\n";
@@ -78,10 +87,13 @@ void CXFA_FMFunctionDefinition::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << RUNTIMEFUNCTIONRETURNVALUE;
   javascript << L" = null;\n";
   for (const auto& expr : m_pExpressions) {
+    bool ret;
     if (expr == m_pExpressions.back())
-      expr->ToImpliedReturnJS(javascript);
+      ret = expr->ToImpliedReturnJS(javascript);
     else
-      expr->ToJavaScript(javascript);
+      ret = expr->ToJavaScript(javascript);
+    if (!ret || CFXA_IsTooBig(javascript))
+      return false;
   }
   javascript << L"return ";
   if (m_isGlobal) {
@@ -96,9 +108,12 @@ void CXFA_FMFunctionDefinition::ToJavaScript(CFX_WideTextBuf& javascript) {
   if (m_isGlobal) {
     javascript << L").call(this);\n";
   }
+  return true;
 }
 
-void CXFA_FMFunctionDefinition::ToImpliedReturnJS(CFX_WideTextBuf&) {}
+bool CXFA_FMFunctionDefinition::ToImpliedReturnJS(CFX_WideTextBuf&) {
+  return true;
+}
 
 CXFA_FMVarExpression::CXFA_FMVarExpression(
     uint32_t line,
@@ -110,7 +125,7 @@ CXFA_FMVarExpression::CXFA_FMVarExpression(
 
 CXFA_FMVarExpression::~CXFA_FMVarExpression() {}
 
-void CXFA_FMVarExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+bool CXFA_FMVarExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"var ";
   CFX_WideString tempName(m_wsName);
   if (m_wsName.GetAt(0) == L'!') {
@@ -119,7 +134,8 @@ void CXFA_FMVarExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << tempName;
   javascript << L" = ";
   if (m_pInit) {
-    m_pInit->ToJavaScript(javascript);
+    if (!m_pInit->ToJavaScript(javascript))
+      return false;
     javascript << tempName;
     javascript << L" = ";
     javascript << XFA_FM_EXPTypeToString(VARFILTER);
@@ -129,9 +145,10 @@ void CXFA_FMVarExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   } else {
     javascript << L"\"\";\n";
   }
+  return true;
 }
 
-void CXFA_FMVarExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+bool CXFA_FMVarExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << L"var ";
   CFX_WideString tempName(m_wsName);
   if (m_wsName.GetAt(0) == L'!') {
@@ -140,7 +157,8 @@ void CXFA_FMVarExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << tempName;
   javascript << L" = ";
   if (m_pInit) {
-    m_pInit->ToJavaScript(javascript);
+    if (!m_pInit->ToJavaScript(javascript))
+      return false;
     javascript << tempName;
     javascript << L" = ";
     javascript << XFA_FM_EXPTypeToString(VARFILTER);
@@ -154,6 +172,7 @@ void CXFA_FMVarExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << L" = ";
   javascript << tempName;
   javascript << L";\n";
+  return true;
 }
 
 CXFA_FMExpExpression::CXFA_FMExpExpression(
@@ -164,37 +183,38 @@ CXFA_FMExpExpression::CXFA_FMExpExpression(
 
 CXFA_FMExpExpression::~CXFA_FMExpExpression() {}
 
-void CXFA_FMExpExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
-  if (m_pExpression->GetOperatorToken() == TOKassign) {
-    m_pExpression->ToJavaScript(javascript);
-  } else {
-    m_pExpression->ToJavaScript(javascript);
+bool CXFA_FMExpExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+  bool ret = m_pExpression->ToJavaScript(javascript);
+  if (m_pExpression->GetOperatorToken() != TOKassign)
     javascript << L";\n";
-  }
+  return ret;
 }
 
-void CXFA_FMExpExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
-  if (m_pExpression->GetOperatorToken() == TOKassign) {
-    m_pExpression->ToImpliedReturnJS(javascript);
-  } else {
-    if (m_pExpression->GetOperatorToken() == TOKstar ||
-        m_pExpression->GetOperatorToken() == TOKdotstar ||
-        m_pExpression->GetOperatorToken() == TOKdotscream ||
-        m_pExpression->GetOperatorToken() == TOKdotdot ||
-        m_pExpression->GetOperatorToken() == TOKdot) {
-      javascript << RUNTIMEFUNCTIONRETURNVALUE;
-      javascript << L" = ";
-      javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
-      javascript << L"(";
-      m_pExpression->ToJavaScript(javascript);
-      javascript << L");\n";
-    } else {
-      javascript << RUNTIMEFUNCTIONRETURNVALUE;
-      javascript << L" = ";
-      m_pExpression->ToJavaScript(javascript);
-      javascript << L";\n";
-    }
+bool CXFA_FMExpExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+  if (m_pExpression->GetOperatorToken() == TOKassign)
+    return m_pExpression->ToImpliedReturnJS(javascript);
+
+  if (m_pExpression->GetOperatorToken() == TOKstar ||
+      m_pExpression->GetOperatorToken() == TOKdotstar ||
+      m_pExpression->GetOperatorToken() == TOKdotscream ||
+      m_pExpression->GetOperatorToken() == TOKdotdot ||
+      m_pExpression->GetOperatorToken() == TOKdot) {
+    javascript << RUNTIMEFUNCTIONRETURNVALUE;
+    javascript << L" = ";
+    javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
+    javascript << L"(";
+    if (!m_pExpression->ToJavaScript(javascript))
+      return false;
+    javascript << L");\n";
+    return true;
   }
+
+  javascript << RUNTIMEFUNCTIONRETURNVALUE;
+  javascript << L" = ";
+  if (!m_pExpression->ToJavaScript(javascript))
+    return false;
+  javascript << L";\n";
+  return true;
 }
 
 CXFA_FMBlockExpression::CXFA_FMBlockExpression(
@@ -205,22 +225,29 @@ CXFA_FMBlockExpression::CXFA_FMBlockExpression(
 
 CXFA_FMBlockExpression::~CXFA_FMBlockExpression() {}
 
-void CXFA_FMBlockExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+bool CXFA_FMBlockExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"{\n";
-  for (const auto& expr : m_ExpressionList)
-    expr->ToJavaScript(javascript);
+  for (const auto& expr : m_ExpressionList) {
+    if (!expr->ToJavaScript(javascript) || CFXA_IsTooBig(javascript))
+      return false;
+  }
   javascript << L"}\n";
+  return true;
 }
 
-void CXFA_FMBlockExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+bool CXFA_FMBlockExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << L"{\n";
   for (const auto& expr : m_ExpressionList) {
+    bool ret;
     if (expr == m_ExpressionList.back())
-      expr->ToImpliedReturnJS(javascript);
+      ret = expr->ToImpliedReturnJS(javascript);
     else
-      expr->ToJavaScript(javascript);
+      ret = expr->ToJavaScript(javascript);
+    if (!ret || CFXA_IsTooBig(javascript))
+      return false;
   }
   javascript << L"}\n";
+  return true;
 }
 
 CXFA_FMDoExpression::CXFA_FMDoExpression(
@@ -230,12 +257,12 @@ CXFA_FMDoExpression::CXFA_FMDoExpression(
 
 CXFA_FMDoExpression::~CXFA_FMDoExpression() {}
 
-void CXFA_FMDoExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
-  m_pList->ToJavaScript(javascript);
+bool CXFA_FMDoExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+  return m_pList->ToJavaScript(javascript);
 }
 
-void CXFA_FMDoExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
-  m_pList->ToImpliedReturnJS(javascript);
+bool CXFA_FMDoExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+  return m_pList->ToImpliedReturnJS(javascript);
 }
 
 CXFA_FMIfExpression::CXFA_FMIfExpression(
@@ -250,63 +277,88 @@ CXFA_FMIfExpression::CXFA_FMIfExpression(
 
 CXFA_FMIfExpression::~CXFA_FMIfExpression() {}
 
-void CXFA_FMIfExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+bool CXFA_FMIfExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"if (";
   if (m_pExpression) {
     javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
     javascript << L"(";
-    m_pExpression->ToJavaScript(javascript);
+    if (!m_pExpression->ToJavaScript(javascript))
+      return false;
     javascript << L")";
   }
   javascript << L")\n";
+  if (CFXA_IsTooBig(javascript))
+    return false;
+
   if (m_pIfExpression) {
-    m_pIfExpression->ToJavaScript(javascript);
+    if (!m_pIfExpression->ToJavaScript(javascript))
+      return false;
+    if (CFXA_IsTooBig(javascript))
+      return false;
   }
+
   if (m_pElseExpression) {
     if (m_pElseExpression->GetExpType() == XFA_FM_EXPTYPE_IF) {
       javascript << L"else\n";
       javascript << L"{\n";
-      m_pElseExpression->ToJavaScript(javascript);
+      if (!m_pElseExpression->ToJavaScript(javascript))
+        return false;
       javascript << L"}\n";
     } else {
       javascript << L"else\n";
-      m_pElseExpression->ToJavaScript(javascript);
+      if (!m_pElseExpression->ToJavaScript(javascript))
+        return false;
     }
   }
+  return !CFXA_IsTooBig(javascript);
 }
 
-void CXFA_FMIfExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+bool CXFA_FMIfExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << RUNTIMEFUNCTIONRETURNVALUE;
   javascript << L" = 0;\n";
   javascript << L"if (";
   if (m_pExpression) {
     javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
     javascript << L"(";
-    m_pExpression->ToJavaScript(javascript);
+    if (!m_pExpression->ToJavaScript(javascript))
+      return false;
     javascript << L")";
   }
   javascript << L")\n";
+  if (CFXA_IsTooBig(javascript))
+    return false;
+
   if (m_pIfExpression) {
-    m_pIfExpression->ToImpliedReturnJS(javascript);
+    if (!m_pIfExpression->ToImpliedReturnJS(javascript))
+      return false;
+    if (CFXA_IsTooBig(javascript))
+      return false;
   }
   if (m_pElseExpression) {
     if (m_pElseExpression->GetExpType() == XFA_FM_EXPTYPE_IF) {
       javascript << L"else\n";
       javascript << L"{\n";
-      m_pElseExpression->ToImpliedReturnJS(javascript);
+      if (!m_pElseExpression->ToImpliedReturnJS(javascript))
+        return false;
       javascript << L"}\n";
     } else {
       javascript << L"else\n";
-      m_pElseExpression->ToImpliedReturnJS(javascript);
+      if (!m_pElseExpression->ToImpliedReturnJS(javascript))
+        return false;
     }
   }
+  return !CFXA_IsTooBig(javascript);
 }
 
 CXFA_FMLoopExpression::~CXFA_FMLoopExpression() {}
 
-void CXFA_FMLoopExpression::ToJavaScript(CFX_WideTextBuf& javascript) {}
+bool CXFA_FMLoopExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+  return true;
+}
 
-void CXFA_FMLoopExpression::ToImpliedReturnJS(CFX_WideTextBuf&) {}
+bool CXFA_FMLoopExpression::ToImpliedReturnJS(CFX_WideTextBuf&) {
+  return true;
+}
 
 CXFA_FMWhileExpression::CXFA_FMWhileExpression(
     uint32_t line,
@@ -318,20 +370,32 @@ CXFA_FMWhileExpression::CXFA_FMWhileExpression(
 
 CXFA_FMWhileExpression::~CXFA_FMWhileExpression() {}
 
-void CXFA_FMWhileExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+bool CXFA_FMWhileExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"while (";
-  m_pCondition->ToJavaScript(javascript);
+  if (!m_pCondition->ToJavaScript(javascript))
+    return false;
   javascript << L")\n";
-  m_pExpression->ToJavaScript(javascript);
+  if (CFXA_IsTooBig(javascript))
+    return false;
+
+  if (!m_pExpression->ToJavaScript(javascript))
+    return false;
+  return !CFXA_IsTooBig(javascript);
 }
 
-void CXFA_FMWhileExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+bool CXFA_FMWhileExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << RUNTIMEFUNCTIONRETURNVALUE;
   javascript << L" = 0;\n";
   javascript << L"while (";
-  m_pCondition->ToJavaScript(javascript);
+  if (!m_pCondition->ToJavaScript(javascript))
+    return false;
   javascript << L")\n";
-  m_pExpression->ToImpliedReturnJS(javascript);
+  if (CFXA_IsTooBig(javascript))
+    return false;
+
+  if (!m_pExpression->ToImpliedReturnJS(javascript))
+    return false;
+  return !CFXA_IsTooBig(javascript);
 }
 
 CXFA_FMBreakExpression::CXFA_FMBreakExpression(uint32_t line)
@@ -339,16 +403,18 @@ CXFA_FMBreakExpression::CXFA_FMBreakExpression(uint32_t line)
 
 CXFA_FMBreakExpression::~CXFA_FMBreakExpression() {}
 
-void CXFA_FMBreakExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+bool CXFA_FMBreakExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << RUNTIMEFUNCTIONRETURNVALUE;
   javascript << L" = 0;\n";
   javascript << L"break;\n";
+  return true;
 }
 
-void CXFA_FMBreakExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+bool CXFA_FMBreakExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << RUNTIMEFUNCTIONRETURNVALUE;
   javascript << L" = 0;\n";
   javascript << L"break;\n";
+  return true;
 }
 
 CXFA_FMContinueExpression::CXFA_FMContinueExpression(uint32_t line)
@@ -356,16 +422,18 @@ CXFA_FMContinueExpression::CXFA_FMContinueExpression(uint32_t line)
 
 CXFA_FMContinueExpression::~CXFA_FMContinueExpression() {}
 
-void CXFA_FMContinueExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+bool CXFA_FMContinueExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << RUNTIMEFUNCTIONRETURNVALUE;
   javascript << L" = 0;\n";
   javascript << L"continue;\n";
+  return true;
 }
 
-void CXFA_FMContinueExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+bool CXFA_FMContinueExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << RUNTIMEFUNCTIONRETURNVALUE;
   javascript << L" = 0;\n";
   javascript << L"continue;\n";
+  return true;
 }
 
 CXFA_FMForExpression::CXFA_FMForExpression(
@@ -380,13 +448,13 @@ CXFA_FMForExpression::CXFA_FMForExpression(
       m_wsVariant(wsVariant),
       m_pAssignment(std::move(pAssignment)),
       m_pAccessor(std::move(pAccessor)),
-      m_iDirection(iDirection),
+      m_bDirection(iDirection == 1),
       m_pStep(std::move(pStep)),
       m_pList(std::move(pList)) {}
 
 CXFA_FMForExpression::~CXFA_FMForExpression() {}
 
-void CXFA_FMForExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+bool CXFA_FMForExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"{\nvar ";
   CFX_WideString tempVariant;
   if (m_wsVariant.GetAt(0) == L'!') {
@@ -402,40 +470,43 @@ void CXFA_FMForExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L" = ";
   javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
   javascript << L"(";
-  m_pAssignment->ToJavaScript(javascript);
+  if (!m_pAssignment->ToJavaScript(javascript))
+    return false;
   javascript << L"); ";
   javascript << tempVariant;
-  if (m_iDirection == 1) {
-    javascript << L" <= ";
-    javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
-    javascript << L"(";
-    m_pAccessor->ToJavaScript(javascript);
-    javascript << L"); ";
-    javascript << tempVariant;
-    javascript << L" += ";
-  } else {
-    javascript << L" >= ";
-    javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
-    javascript << L"(";
-    m_pAccessor->ToJavaScript(javascript);
-    javascript << L"); ";
-    javascript << tempVariant;
-    javascript << L" -= ";
-  }
+  if (CFXA_IsTooBig(javascript))
+    return false;
+
+  javascript << (m_bDirection ? kLessEqual : kGreaterEqual);
+  javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
+  javascript << L"(";
+  if (!m_pAccessor->ToJavaScript(javascript))
+    return false;
+  javascript << L"); ";
+  javascript << tempVariant;
+  javascript << (m_bDirection ? kPlusEqual : kMinusEqual);
+  if (CFXA_IsTooBig(javascript))
+    return false;
+
   if (m_pStep) {
     javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
     javascript << L"(";
-    m_pStep->ToJavaScript(javascript);
+    if (!m_pStep->ToJavaScript(javascript))
+      return false;
     javascript << L")";
+    if (CFXA_IsTooBig(javascript))
+      return false;
   } else {
     javascript << L"1";
   }
   javascript << L")\n";
-  m_pList->ToJavaScript(javascript);
+  if (!m_pList->ToJavaScript(javascript))
+    return false;
   javascript << L"}\n";
+  return !CFXA_IsTooBig(javascript);
 }
 
-void CXFA_FMForExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+bool CXFA_FMForExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << RUNTIMEFUNCTIONRETURNVALUE;
   javascript << L" = 0;\n";
   javascript << L"{\nvar ";
@@ -453,37 +524,41 @@ void CXFA_FMForExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << L" = ";
   javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
   javascript << L"(";
-  m_pAssignment->ToJavaScript(javascript);
+  if (!m_pAssignment->ToJavaScript(javascript))
+    return false;
   javascript << L"); ";
   javascript << tempVariant;
-  if (m_iDirection == 1) {
-    javascript << L" <= ";
-    javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
-    javascript << L"(";
-    m_pAccessor->ToJavaScript(javascript);
-    javascript << L"); ";
-    javascript << tempVariant;
-    javascript << L" += ";
-  } else {
-    javascript << L" >= ";
-    javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
-    javascript << L"(";
-    m_pAccessor->ToJavaScript(javascript);
-    javascript << L"); ";
-    javascript << tempVariant;
-    javascript << L" -= ";
-  }
+  if (CFXA_IsTooBig(javascript))
+    return false;
+
+  javascript << (m_bDirection ? kLessEqual : kGreaterEqual);
+  javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
+  javascript << L"(";
+  if (!m_pAccessor->ToJavaScript(javascript))
+    return false;
+  javascript << L"); ";
+  javascript << tempVariant;
+  javascript << L" += ";
+  javascript << (m_bDirection ? kPlusEqual : kMinusEqual);
+  if (CFXA_IsTooBig(javascript))
+    return false;
+
   if (m_pStep) {
     javascript << XFA_FM_EXPTypeToString(GETFMVALUE);
     javascript << L"(";
-    m_pStep->ToJavaScript(javascript);
+    if (!m_pStep->ToJavaScript(javascript))
+      return false;
     javascript << L")";
+    if (CFXA_IsTooBig(javascript))
+      return false;
   } else {
     javascript << L"1";
   }
   javascript << L")\n";
-  m_pList->ToImpliedReturnJS(javascript);
+  if (!m_pList->ToImpliedReturnJS(javascript))
+    return false;
   javascript << L"}\n";
+  return !CFXA_IsTooBig(javascript);
 }
 
 CXFA_FMForeachExpression::CXFA_FMForeachExpression(
@@ -498,7 +573,7 @@ CXFA_FMForeachExpression::CXFA_FMForeachExpression(
 
 CXFA_FMForeachExpression::~CXFA_FMForeachExpression() {}
 
-void CXFA_FMForeachExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
+bool CXFA_FMForeachExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"{\n";
   javascript << L"var ";
   if (m_wsIdentifier.GetAt(0) == L'!') {
@@ -516,9 +591,12 @@ void CXFA_FMForeachExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"(";
 
   for (const auto& expr : m_pAccessors) {
-    expr->ToJavaScript(javascript);
+    if (!expr->ToJavaScript(javascript))
+      return false;
     if (expr != m_pAccessors.back())
       javascript << L", ";
+    if (CFXA_IsTooBig(javascript))
+      return false;
   }
   javascript << L");\n";
   javascript << L"var ";
@@ -541,12 +619,14 @@ void CXFA_FMForeachExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"[";
   javascript << RUNTIMEBLOCKTEMPARRAYINDEX;
   javascript << L"++];\n";
-  m_pList->ToJavaScript(javascript);
+  if (!m_pList->ToJavaScript(javascript))
+    return false;
   javascript << L"}\n";
   javascript << L"}\n";
+  return !CFXA_IsTooBig(javascript);
 }
 
-void CXFA_FMForeachExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
+bool CXFA_FMForeachExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << RUNTIMEFUNCTIONRETURNVALUE;
   javascript << L" = 0;\n";
   javascript << L"{\n";
@@ -565,9 +645,12 @@ void CXFA_FMForeachExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << XFA_FM_EXPTypeToString(CONCATFMOBJECT);
   javascript << L"(";
   for (const auto& expr : m_pAccessors) {
-    expr->ToJavaScript(javascript);
+    if (!expr->ToJavaScript(javascript))
+      return false;
     if (expr != m_pAccessors.back())
       javascript << L", ";
+    if (CFXA_IsTooBig(javascript))
+      return false;
   }
   javascript << L");\n";
   javascript << L"var ";
@@ -590,7 +673,9 @@ void CXFA_FMForeachExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << L"[";
   javascript << RUNTIMEBLOCKTEMPARRAYINDEX;
   javascript << L"++];\n";
-  m_pList->ToImpliedReturnJS(javascript);
+  if (!m_pList->ToImpliedReturnJS(javascript))
+    return false;
   javascript << L"}\n";
   javascript << L"}\n";
+  return !CFXA_IsTooBig(javascript);
 }