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// Copyright 2018 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_stream.h"
#include <utility>
#include "core/fpdfapi/parser/cpdf_dictionary.h"
#include "core/fpdfapi/parser/cpdf_number.h"
#include "core/fpdfapi/parser/cpdf_parser.h"
#include "core/fpdfapi/parser/cpdf_reference.h"
#include "core/fpdfapi/parser/cpdf_stream.h"
#include "core/fpdfapi/parser/cpdf_stream_acc.h"
#include "core/fpdfapi/parser/cpdf_syntax_parser.h"
#include "core/fxcrt/cfx_memorystream.h"
#include "third_party/base/stl_util.h"
// static
bool CPDF_ObjectStream::IsObjectsStreamObject(const CPDF_Object* object) {
const CPDF_Stream* stream = ToStream(object);
if (!stream)
return false;
const CPDF_Dictionary* stream_dict = stream->GetDict();
if (!stream_dict)
return false;
if (stream_dict->GetStringFor("Type") != "ObjStm")
return false;
const CPDF_Number* number_of_objects =
ToNumber(stream_dict->GetObjectFor("N"));
if (!number_of_objects || !number_of_objects->IsInteger() ||
number_of_objects->GetInteger() < 0 ||
number_of_objects->GetInteger() >=
static_cast<int>(CPDF_Parser::kMaxObjectNumber)) {
return false;
}
const CPDF_Number* first_object_offset =
ToNumber(stream_dict->GetObjectFor("First"));
if (!first_object_offset || !first_object_offset->IsInteger() ||
first_object_offset->GetInteger() < 0) {
return false;
}
return true;
}
// static
std::unique_ptr<CPDF_ObjectStream> CPDF_ObjectStream::Create(
const CPDF_Stream* stream) {
if (!IsObjectsStreamObject(stream))
return nullptr;
// The ctor of CPDF_ObjectStream is protected. Use WrapUnique instead
// MakeUnique.
return pdfium::WrapUnique(new CPDF_ObjectStream(stream));
}
CPDF_ObjectStream::CPDF_ObjectStream(const CPDF_Stream* obj_stream)
: obj_num_(obj_stream->GetObjNum()),
first_object_offset_(obj_stream->GetDict()->GetIntegerFor("First")) {
ASSERT(IsObjectsStreamObject(obj_stream));
if (const auto* extends_ref =
ToReference(obj_stream->GetDict()->GetObjectFor("Extends"))) {
extends_obj_num_ = extends_ref->GetRefObjNum();
}
Init(obj_stream);
}
CPDF_ObjectStream::~CPDF_ObjectStream() = default;
bool CPDF_ObjectStream::HasObject(uint32_t obj_number) const {
return pdfium::ContainsKey(objects_offsets_, obj_number);
}
std::unique_ptr<CPDF_Object> CPDF_ObjectStream::ParseObject(
CPDF_IndirectObjectHolder* pObjList,
uint32_t obj_number) const {
const auto it = objects_offsets_.find(obj_number);
if (it == objects_offsets_.end())
return nullptr;
std::unique_ptr<CPDF_Object> result =
ParseObjectAtOffset(pObjList, it->second);
if (!result)
return nullptr;
result->SetObjNum(obj_number);
return result;
}
void CPDF_ObjectStream::Init(const CPDF_Stream* stream) {
{
auto stream_acc = pdfium::MakeRetain<CPDF_StreamAcc>(stream);
stream_acc->LoadAllDataFiltered();
const uint32_t data_size = stream_acc->GetSize();
data_stream_ = pdfium::MakeRetain<CFX_MemoryStream>(
stream_acc->DetachData(), data_size);
}
CPDF_SyntaxParser syntax(data_stream_);
const int object_count = stream->GetDict()->GetIntegerFor("N");
for (int32_t i = object_count; i > 0; --i) {
if (syntax.GetPos() >= data_stream_->GetSize())
break;
const uint32_t obj_num = syntax.GetDirectNum();
const uint32_t obj_offset = syntax.GetDirectNum();
if (!obj_num)
continue;
objects_offsets_[obj_num] = obj_offset;
}
}
std::unique_ptr<CPDF_Object> CPDF_ObjectStream::ParseObjectAtOffset(
CPDF_IndirectObjectHolder* pObjList,
uint32_t object_offset) const {
FX_SAFE_FILESIZE offset_in_stream = first_object_offset_;
offset_in_stream += object_offset;
if (!offset_in_stream.IsValid())
return nullptr;
if (offset_in_stream.ValueOrDie() >= data_stream_->GetSize())
return nullptr;
CPDF_SyntaxParser syntax(data_stream_);
syntax.SetPos(offset_in_stream.ValueOrDie());
return syntax.GetObjectBody(pObjList);
}
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