Unify some code

core/fpdfapi/parser/cpdf_linearized.cpp

+// Copyright 2016 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#include "core/fpdfapi/parser/cpdf_linearized.h"
+
+#include "core/fpdfapi/parser/cpdf_array.h"
+#include "core/fpdfapi/parser/cpdf_dictionary.h"
+#include "core/fpdfapi/parser/cpdf_number.h"
+#include "third_party/base/ptr_util.h"
+
+namespace {
+
+template <class T>
+bool IsValidNumericDictionaryValue(const CPDF_Dictionary* pDict,
+                                   const char* key,
+                                   T min_value,
+                                   bool must_exist = true) {
+  if (!pDict->KeyExist(key))
+    return !must_exist;
+  const CPDF_Number* pNum = ToNumber(pDict->GetObjectFor(key));
+  if (!pNum || !pNum->IsInteger())
+    return false;
+  const int raw_value = pNum->GetInteger();
+  if (!pdfium::base::IsValueInRangeForNumericType<T>(raw_value))
+    return false;
+  return static_cast<T>(raw_value) >= min_value;
+}
+
+}  // namespace
+
+// static
+std::unique_ptr<CPDF_Linearized> CPDF_Linearized::CreateForObject(
+    std::unique_ptr<CPDF_Object> pObj) {
+  auto pDict = ToDictionary(std::move(pObj));
+  if (!pDict || !pDict->KeyExist("Linearized") ||
+      !IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "L", 1) ||
+      !IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "P", 0, false) ||
+      !IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "T", 1) ||
+      !IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "N", 0) ||
+      !IsValidNumericDictionaryValue<FX_FILESIZE>(pDict.get(), "E", 1) ||
+      !IsValidNumericDictionaryValue<uint32_t>(pDict.get(), "O", 1))
+    return nullptr;
+  return pdfium::WrapUnique(new CPDF_Linearized(pDict.get()));
+}
+
+CPDF_Linearized::CPDF_Linearized(const CPDF_Dictionary* pDict) {
+  m_szFileSize = pDict->GetIntegerFor("L");
+  m_dwFirstPageNo = pDict->GetIntegerFor("P");
+  m_szLastXRefOffset = pDict->GetIntegerFor("T");
+  m_PageCount = pDict->GetIntegerFor("N");
+  m_szFirstPageEndOffset = pDict->GetIntegerFor("E");
+  m_FirstPageObjNum = pDict->GetIntegerFor("O");
+  const CPDF_Array* pHintStreamRange = pDict->GetArrayFor("H");
+  const size_t nHintStreamSize =
+      pHintStreamRange ? pHintStreamRange->GetCount() : 0;
+  if (nHintStreamSize == 2 || nHintStreamSize == 4) {
+    m_szHintStart = std::max(pHintStreamRange->GetIntegerAt(0), 0);
+    m_szHintLength = std::max(pHintStreamRange->GetIntegerAt(1), 0);
+  }
+}
+
+CPDF_Linearized::~CPDF_Linearized() {}
+
+bool CPDF_Linearized::HasHintTable() const {
+  return GetPageCount() > 1 && GetHintStart() > 0 && GetHintLength() > 0;
+}