From 304eefb58759e56be3fb357c78204accd4fa98fc Mon Sep 17 00:00:00 2001
From: Artem Strygin <art-snake@yandex-team.ru>
Date: Tue, 29 Aug 2017 00:26:42 +0300
Subject: Implement CPDF_ObjectAvail.

This is non recursive replacement for CPDF_DataAvail::AreObjectsAvailable.

Also added tests.

Change-Id: I546289fc0963d2343253755850f55af8c0bd8e4c
Reviewed-on: https://pdfium-review.googlesource.com/11430
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Art Snake <art-snake@yandex-team.ru>
---
 core/fpdfapi/parser/cpdf_object_avail.cpp | 148 ++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 core/fpdfapi/parser/cpdf_object_avail.cpp

(limited to 'core/fpdfapi/parser/cpdf_object_avail.cpp')

diff --git a/core/fpdfapi/parser/cpdf_object_avail.cpp b/core/fpdfapi/parser/cpdf_object_avail.cpp
new file mode 100644
index 0000000000..35e7f45850
--- /dev/null
+++ b/core/fpdfapi/parser/cpdf_object_avail.cpp
@@ -0,0 +1,148 @@
+// Copyright 2017 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.
+
+#include "core/fpdfapi/parser/cpdf_object_avail.h"
+
+#include <utility>
+
+#include "core/fpdfapi/parser/cpdf_dictionary.h"
+#include "core/fpdfapi/parser/cpdf_indirect_object_holder.h"
+#include "core/fpdfapi/parser/cpdf_object_walker.h"
+#include "core/fpdfapi/parser/cpdf_read_validator.h"
+#include "core/fpdfapi/parser/cpdf_reference.h"
+
+CPDF_ObjectAvail::CPDF_ObjectAvail(CPDF_ReadValidator* validator,
+                                   CPDF_IndirectObjectHolder* holder,
+                                   const CPDF_Object* root)
+    : validator_(validator), holder_(holder), root_(root) {
+  ASSERT(validator_);
+  ASSERT(holder);
+  ASSERT(root_);
+  if (!root_->IsInline())
+    parsed_objnums_.insert(root_->GetObjNum());
+}
+
+CPDF_ObjectAvail::CPDF_ObjectAvail(CPDF_ReadValidator* validator,
+                                   CPDF_IndirectObjectHolder* holder,
+                                   uint32_t obj_num)
+    : validator_(validator),
+      holder_(holder),
+      root_(pdfium::MakeUnique<CPDF_Reference>(holder, obj_num)) {
+  ASSERT(validator_);
+  ASSERT(holder);
+}
+
+CPDF_ObjectAvail::~CPDF_ObjectAvail() {}
+
+CPDF_DataAvail::DocAvailStatus CPDF_ObjectAvail::CheckAvail() {
+  if (!LoadRootObject())
+    return CPDF_DataAvail::DocAvailStatus::DataNotAvailable;
+
+  if (CheckObjects()) {
+    CleanMemory();
+    return CPDF_DataAvail::DocAvailStatus::DataAvailable;
+  }
+  return CPDF_DataAvail::DocAvailStatus::DataNotAvailable;
+}
+
+bool CPDF_ObjectAvail::LoadRootObject() {
+  if (!non_parsed_objects_.empty())
+    return true;
+
+  while (root_ && root_->IsReference()) {
+    const uint32_t ref_obj_num = root_->AsReference()->GetRefObjNum();
+    if (HasObjectParsed(ref_obj_num)) {
+      root_ = nullptr;
+      return true;
+    }
+
+    const CPDF_ReadValidator::Session parse_session(validator_.Get());
+    const CPDF_Object* direct = holder_->GetOrParseIndirectObject(ref_obj_num);
+    if (validator_->has_read_problems())
+      return false;
+
+    parsed_objnums_.insert(ref_obj_num);
+    root_ = direct;
+  }
+  std::stack<uint32_t> non_parsed_objects_in_root;
+  if (AppendObjectSubRefs(root_.Get(), &non_parsed_objects_in_root)) {
+    non_parsed_objects_ = std::move(non_parsed_objects_in_root);
+    return true;
+  }
+  return false;
+}
+
+bool CPDF_ObjectAvail::CheckObjects() {
+  std::stack<uint32_t> objects_to_check = std::move(non_parsed_objects_);
+  std::set<uint32_t> checked_objects;
+  while (!objects_to_check.empty()) {
+    const uint32_t obj_num = objects_to_check.top();
+    objects_to_check.pop();
+
+    if (HasObjectParsed(obj_num))
+      continue;
+
+    if (!checked_objects.insert(obj_num).second)
+      continue;
+
+    const CPDF_ReadValidator::Session parse_session(validator_.Get());
+    const CPDF_Object* direct = holder_->GetOrParseIndirectObject(obj_num);
+    if (direct == root_.Get())
+      continue;
+
+    if (validator_->has_read_problems() ||
+        !AppendObjectSubRefs(direct, &objects_to_check)) {
+      non_parsed_objects_.push(obj_num);
+      continue;
+    }
+    parsed_objnums_.insert(obj_num);
+  }
+  return non_parsed_objects_.empty();
+}
+
+bool CPDF_ObjectAvail::AppendObjectSubRefs(const CPDF_Object* object,
+                                           std::stack<uint32_t>* refs) const {
+  ASSERT(refs);
+  if (!object)
+    return true;
+
+  CPDF_ObjectWalker walker(object);
+  while (const CPDF_Object* obj = walker.GetNext()) {
+    const CPDF_ReadValidator::Session parse_session(validator_.Get());
+
+    // Skip if this object if it's an inlined root, the parent object or
+    // explicitily excluded.
+    const bool skip = (walker.GetParent() && obj == root_.Get()) ||
+                      walker.dictionary_key() == "Parent" ||
+                      (obj != root_.Get() && ExcludeObject(obj));
+
+    // We need to parse the object before we can do the exclusion check.
+    // This is because the exclusion check may check against a referenced
+    // field of the object which we need to make sure is loaded.
+    if (validator_->has_read_problems())
+      return false;
+
+    if (skip) {
+      walker.SkipWalkIntoCurrentObject();
+      continue;
+    }
+
+    if (obj->IsReference())
+      refs->push(obj->AsReference()->GetRefObjNum());
+  }
+  return true;
+}
+
+void CPDF_ObjectAvail::CleanMemory() {
+  root_.Reset();
+  parsed_objnums_.clear();
+}
+
+bool CPDF_ObjectAvail::ExcludeObject(const CPDF_Object* object) const {
+  return false;
+}
+
+bool CPDF_ObjectAvail::HasObjectParsed(uint32_t obj_num) const {
+  return parsed_objnums_.count(obj_num) > 0;
+}
-- 
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