blob: 2a3e07e843f9e5af4eda4276fd994f0f32c28033 [file] [log] [blame]
// Copyright 2016 The PDFium Authors
// 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_parser.h"
#include <ctype.h>
#include <stdint.h>
#include <algorithm>
#include <utility>
#include <vector>
#include "core/fpdfapi/parser/cpdf_array.h"
#include "core/fpdfapi/parser/cpdf_crypto_handler.h"
#include "core/fpdfapi/parser/cpdf_dictionary.h"
#include "core/fpdfapi/parser/cpdf_document.h"
#include "core/fpdfapi/parser/cpdf_linearized_header.h"
#include "core/fpdfapi/parser/cpdf_number.h"
#include "core/fpdfapi/parser/cpdf_object_stream.h"
#include "core/fpdfapi/parser/cpdf_read_validator.h"
#include "core/fpdfapi/parser/cpdf_reference.h"
#include "core/fpdfapi/parser/cpdf_security_handler.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/fpdfapi/parser/fpdf_parser_utility.h"
#include "core/fxcrt/autorestorer.h"
#include "core/fxcrt/data_vector.h"
#include "core/fxcrt/fx_extension.h"
#include "core/fxcrt/fx_safe_types.h"
#include "core/fxcrt/scoped_set_insertion.h"
#include "third_party/base/check.h"
#include "third_party/base/check_op.h"
#include "third_party/base/containers/contains.h"
#include "third_party/base/containers/span.h"
#include "third_party/base/notreached.h"
namespace {
// A limit on the size of the xref table. Theoretical limits are higher, but
// this may be large enough in practice. The max size should always be 1 more
// than the max object number.
constexpr int32_t kMaxXRefSize = CPDF_Parser::kMaxObjectNumber + 1;
// "%PDF-1.7\n"
constexpr FX_FILESIZE kPDFHeaderSize = 9;
// The required number of fields in a /W array in a cross-reference stream
// dictionary.
constexpr size_t kMinFieldCount = 3;
// V4 trailers are inline.
constexpr uint32_t kNoV4TrailerObjectNumber = 0;
struct CrossRefV5IndexEntry {
uint32_t start_obj_num;
uint32_t obj_count;
};
CPDF_Parser::ObjectType GetObjectTypeFromCrossRefStreamType(
uint32_t cross_ref_stream_type) {
switch (cross_ref_stream_type) {
case 0:
return CPDF_Parser::ObjectType::kFree;
case 1:
return CPDF_Parser::ObjectType::kNormal;
case 2:
return CPDF_Parser::ObjectType::kCompressed;
default:
return CPDF_Parser::ObjectType::kNull;
}
}
// Use the Get*XRefStreamEntry() functions below, instead of calling this
// directly.
uint32_t GetVarInt(pdfium::span<const uint8_t> input) {
uint32_t result = 0;
for (uint8_t c : input)
result = result * 256 + c;
return result;
}
// The following 3 functions retrieve variable length entries from
// cross-reference streams, as described in ISO 32000-1:2008 table 18. There are
// only 3 fields for any given entry.
uint32_t GetFirstXRefStreamEntry(pdfium::span<const uint8_t> entry_span,
pdfium::span<const uint32_t> field_widths) {
return GetVarInt(entry_span.first(field_widths[0]));
}
uint32_t GetSecondXRefStreamEntry(pdfium::span<const uint8_t> entry_span,
pdfium::span<const uint32_t> field_widths) {
return GetVarInt(entry_span.subspan(field_widths[0], field_widths[1]));
}
uint32_t GetThirdXRefStreamEntry(pdfium::span<const uint8_t> entry_span,
pdfium::span<const uint32_t> field_widths) {
return GetVarInt(
entry_span.subspan(field_widths[0] + field_widths[1], field_widths[2]));
}
std::vector<CrossRefV5IndexEntry> GetCrossRefV5Indices(const CPDF_Array* array,
uint32_t size) {
std::vector<CrossRefV5IndexEntry> indices;
if (array) {
for (size_t i = 0; i < array->size() / 2; i++) {
RetainPtr<const CPDF_Number> pStartNumObj = array->GetNumberAt(i * 2);
if (!pStartNumObj)
continue;
RetainPtr<const CPDF_Number> pCountObj = array->GetNumberAt(i * 2 + 1);
if (!pCountObj)
continue;
int nStartNum = pStartNumObj->GetInteger();
int nCount = pCountObj->GetInteger();
if (nStartNum < 0 || nCount <= 0)
continue;
indices.push_back(
{static_cast<uint32_t>(nStartNum), static_cast<uint32_t>(nCount)});
}
}
if (indices.empty())
indices.push_back({0, size});
return indices;
}
std::vector<uint32_t> GetFieldWidths(const CPDF_Array* array) {
std::vector<uint32_t> results;
if (!array)
return results;
CPDF_ArrayLocker locker(array);
for (const auto& obj : locker)
results.push_back(obj->GetInteger());
return results;
}
class ObjectsHolderStub final : public CPDF_Parser::ParsedObjectsHolder {
public:
ObjectsHolderStub() = default;
~ObjectsHolderStub() override = default;
bool TryInit() override { return true; }
};
} // namespace
CPDF_Parser::CPDF_Parser(ParsedObjectsHolder* holder)
: m_pObjectsHolder(holder),
m_CrossRefTable(std::make_unique<CPDF_CrossRefTable>()) {
if (!holder) {
m_pOwnedObjectsHolder = std::make_unique<ObjectsHolderStub>();
m_pObjectsHolder = m_pOwnedObjectsHolder.get();
}
}
CPDF_Parser::CPDF_Parser() : CPDF_Parser(nullptr) {}
CPDF_Parser::~CPDF_Parser() = default;
uint32_t CPDF_Parser::GetLastObjNum() const {
return m_CrossRefTable->objects_info().empty()
? 0
: m_CrossRefTable->objects_info().rbegin()->first;
}
bool CPDF_Parser::IsValidObjectNumber(uint32_t objnum) const {
return objnum <= GetLastObjNum();
}
FX_FILESIZE CPDF_Parser::GetObjectPositionOrZero(uint32_t objnum) const {
const auto* info = m_CrossRefTable->GetObjectInfo(objnum);
return (info && info->type == ObjectType::kNormal) ? info->pos : 0;
}
CPDF_Parser::ObjectType CPDF_Parser::GetObjectType(uint32_t objnum) const {
DCHECK(IsValidObjectNumber(objnum));
const auto* info = m_CrossRefTable->GetObjectInfo(objnum);
return info ? info->type : ObjectType::kFree;
}
bool CPDF_Parser::IsObjectFreeOrNull(uint32_t objnum) const {
switch (GetObjectType(objnum)) {
case ObjectType::kFree:
case ObjectType::kNull:
return true;
case ObjectType::kNormal:
case ObjectType::kCompressed:
return false;
}
NOTREACHED_NORETURN();
}
bool CPDF_Parser::IsObjectFree(uint32_t objnum) const {
return GetObjectType(objnum) == ObjectType::kFree;
}
bool CPDF_Parser::InitSyntaxParser(RetainPtr<CPDF_ReadValidator> validator) {
const absl::optional<FX_FILESIZE> header_offset = GetHeaderOffset(validator);
if (!header_offset.has_value())
return false;
if (validator->GetSize() < header_offset.value() + kPDFHeaderSize)
return false;
m_pSyntax = std::make_unique<CPDF_SyntaxParser>(std::move(validator),
header_offset.value());
return ParseFileVersion();
}
bool CPDF_Parser::ParseFileVersion() {
m_FileVersion = 0;
uint8_t ch;
if (!m_pSyntax->GetCharAt(5, ch))
return false;
if (isdigit(ch))
m_FileVersion = FXSYS_DecimalCharToInt(static_cast<wchar_t>(ch)) * 10;
if (!m_pSyntax->GetCharAt(7, ch))
return false;
if (isdigit(ch))
m_FileVersion += FXSYS_DecimalCharToInt(static_cast<wchar_t>(ch));
return true;
}
CPDF_Parser::Error CPDF_Parser::StartParse(
RetainPtr<IFX_SeekableReadStream> pFileAccess,
const ByteString& password) {
if (!InitSyntaxParser(pdfium::MakeRetain<CPDF_ReadValidator>(
std::move(pFileAccess), nullptr)))
return FORMAT_ERROR;
SetPassword(password);
return StartParseInternal();
}
CPDF_Parser::Error CPDF_Parser::StartParseInternal() {
DCHECK(!m_bHasParsed);
DCHECK(!m_bXRefTableRebuilt);
m_bHasParsed = true;
m_bXRefStream = false;
m_LastXRefOffset = ParseStartXRef();
if (m_LastXRefOffset >= kPDFHeaderSize) {
if (!LoadAllCrossRefV4(m_LastXRefOffset) &&
!LoadAllCrossRefV5(m_LastXRefOffset)) {
if (!RebuildCrossRef())
return FORMAT_ERROR;
m_bXRefTableRebuilt = true;
m_LastXRefOffset = 0;
}
} else {
if (!RebuildCrossRef())
return FORMAT_ERROR;
m_bXRefTableRebuilt = true;
}
Error eRet = SetEncryptHandler();
if (eRet != SUCCESS)
return eRet;
if (!GetRoot() || !m_pObjectsHolder->TryInit()) {
if (m_bXRefTableRebuilt)
return FORMAT_ERROR;
ReleaseEncryptHandler();
if (!RebuildCrossRef())
return FORMAT_ERROR;
eRet = SetEncryptHandler();
if (eRet != SUCCESS)
return eRet;
m_pObjectsHolder->TryInit();
if (!GetRoot())
return FORMAT_ERROR;
}
if (GetRootObjNum() == CPDF_Object::kInvalidObjNum) {
ReleaseEncryptHandler();
if (!RebuildCrossRef() || GetRootObjNum() == CPDF_Object::kInvalidObjNum)
return FORMAT_ERROR;
eRet = SetEncryptHandler();
if (eRet != SUCCESS)
return eRet;
}
if (m_pSecurityHandler && !m_pSecurityHandler->IsMetadataEncrypted()) {
RetainPtr<const CPDF_Reference> pMetadata =
ToReference(GetRoot()->GetObjectFor("Metadata"));
if (pMetadata)
m_MetadataObjnum = pMetadata->GetRefObjNum();
}
return SUCCESS;
}
FX_FILESIZE CPDF_Parser::ParseStartXRef() {
static constexpr char kStartXRefKeyword[] = "startxref";
m_pSyntax->SetPos(m_pSyntax->GetDocumentSize() - strlen(kStartXRefKeyword));
if (!m_pSyntax->BackwardsSearchToWord(kStartXRefKeyword, 4096))
return 0;
// Skip "startxref" keyword.
m_pSyntax->GetKeyword();
// Read XRef offset.
const CPDF_SyntaxParser::WordResult xref_offset_result =
m_pSyntax->GetNextWord();
if (!xref_offset_result.is_number || xref_offset_result.word.IsEmpty())
return 0;
const FX_SAFE_FILESIZE result = FXSYS_atoi64(xref_offset_result.word.c_str());
if (!result.IsValid() || result.ValueOrDie() >= m_pSyntax->GetDocumentSize())
return 0;
return result.ValueOrDie();
}
CPDF_Parser::Error CPDF_Parser::SetEncryptHandler() {
ReleaseEncryptHandler();
if (!GetTrailer())
return FORMAT_ERROR;
RetainPtr<const CPDF_Dictionary> pEncryptDict = GetEncryptDict();
if (!pEncryptDict)
return SUCCESS;
if (pEncryptDict->GetNameFor("Filter") != "Standard")
return HANDLER_ERROR;
auto pSecurityHandler = pdfium::MakeRetain<CPDF_SecurityHandler>();
if (!pSecurityHandler->OnInit(pEncryptDict, GetIDArray(), GetPassword()))
return PASSWORD_ERROR;
m_pSecurityHandler = std::move(pSecurityHandler);
return SUCCESS;
}
void CPDF_Parser::ReleaseEncryptHandler() {
m_pSecurityHandler.Reset();
}
// Ideally, all the cross reference entries should be verified.
// In reality, we rarely see well-formed cross references don't match
// with the objects. crbug/602650 showed a case where object numbers
// in the cross reference table are all off by one.
bool CPDF_Parser::VerifyCrossRefV4() {
for (const auto& it : m_CrossRefTable->objects_info()) {
if (it.second.pos <= 0)
continue;
// Find the first non-zero position.
FX_FILESIZE SavedPos = m_pSyntax->GetPos();
m_pSyntax->SetPos(it.second.pos);
CPDF_SyntaxParser::WordResult word_result = m_pSyntax->GetNextWord();
m_pSyntax->SetPos(SavedPos);
if (!word_result.is_number || word_result.word.IsEmpty() ||
FXSYS_atoui(word_result.word.c_str()) != it.first) {
// If the object number read doesn't match the one stored,
// something is wrong with the cross reference table.
return false;
}
break;
}
return true;
}
bool CPDF_Parser::LoadAllCrossRefV4(FX_FILESIZE xref_offset) {
if (!LoadCrossRefV4(xref_offset, true))
return false;
RetainPtr<CPDF_Dictionary> trailer = LoadTrailerV4();
if (!trailer)
return false;
m_CrossRefTable->SetTrailer(std::move(trailer), kNoV4TrailerObjectNumber);
const int32_t xrefsize = GetTrailer()->GetDirectIntegerFor("Size");
if (xrefsize > 0 && xrefsize <= kMaxXRefSize)
m_CrossRefTable->SetObjectMapSize(xrefsize);
FX_FILESIZE xref_stm = GetTrailer()->GetDirectIntegerFor("XRefStm");
std::vector<FX_FILESIZE> xref_stream_list{xref_stm};
std::vector<FX_FILESIZE> xref_list{xref_offset};
std::set<FX_FILESIZE> seen_xref_offset{xref_offset};
// When the trailer doesn't have Prev entry or Prev entry value is not
// numerical, GetDirectInteger() returns 0. Loading will end.
xref_offset = GetTrailer()->GetDirectIntegerFor("Prev");
while (xref_offset > 0) {
// Check for circular references.
if (pdfium::Contains(seen_xref_offset, xref_offset))
return false;
seen_xref_offset.insert(xref_offset);
xref_list.insert(xref_list.begin(), xref_offset);
// SLOW ...
LoadCrossRefV4(xref_offset, true);
RetainPtr<CPDF_Dictionary> pDict(LoadTrailerV4());
if (!pDict)
return false;
xref_offset = pDict->GetDirectIntegerFor("Prev");
xref_stm = pDict->GetIntegerFor("XRefStm");
xref_stream_list.insert(xref_stream_list.begin(), xref_stm);
// SLOW ...
m_CrossRefTable = CPDF_CrossRefTable::MergeUp(
std::make_unique<CPDF_CrossRefTable>(std::move(pDict),
kNoV4TrailerObjectNumber),
std::move(m_CrossRefTable));
}
// Traverse the xref data structures from oldest to newest. So entries from
// later iterations should overwrite existing entries.
for (size_t i = 0; i < xref_list.size(); ++i) {
if (xref_list[i] > 0 && !LoadCrossRefV4(xref_list[i], false))
return false;
if (xref_stream_list[i] > 0 &&
!LoadCrossRefV5(&xref_stream_list[i], /*is_main_xref=*/false,
/*overwrite_existing=*/true)) {
return false;
}
if (i == 0 && !VerifyCrossRefV4())
return false;
}
return true;
}
bool CPDF_Parser::LoadLinearizedAllCrossRefV4(FX_FILESIZE main_xref_offset) {
if (!LoadCrossRefV4(main_xref_offset, false))
return false;
RetainPtr<CPDF_Dictionary> main_trailer = LoadTrailerV4();
if (!main_trailer)
return false;
// GetTrailer() currently returns the first-page trailer.
if (GetTrailer()->GetDirectIntegerFor("Size") == 0)
return false;
// Read /XRefStm from the first-page trailer. No need to read /Prev for the
// first-page trailer, as the caller already did that and passed it in as
// |main_xref_offset|.
FX_FILESIZE xref_stm = GetTrailer()->GetDirectIntegerFor("XRefStm");
std::vector<FX_FILESIZE> xref_stream_list{xref_stm};
std::vector<FX_FILESIZE> xref_list{main_xref_offset};
std::set<FX_FILESIZE> seen_xref_offset{main_xref_offset};
// Merge the trailers.
m_CrossRefTable = CPDF_CrossRefTable::MergeUp(
std::make_unique<CPDF_CrossRefTable>(std::move(main_trailer),
kNoV4TrailerObjectNumber),
std::move(m_CrossRefTable));
// Now GetTrailer() returns the merged trailer, where /Prev is from the
// main-trailer.
FX_FILESIZE xref_offset = GetTrailer()->GetDirectIntegerFor("Prev");
while (xref_offset > 0) {
// Check for circular references.
if (pdfium::Contains(seen_xref_offset, xref_offset))
return false;
seen_xref_offset.insert(xref_offset);
xref_list.insert(xref_list.begin(), xref_offset);
// SLOW ...
LoadCrossRefV4(xref_offset, true);
RetainPtr<CPDF_Dictionary> pDict(LoadTrailerV4());
if (!pDict)
return false;
xref_offset = pDict->GetDirectIntegerFor("Prev");
xref_stm = pDict->GetIntegerFor("XRefStm");
xref_stream_list.insert(xref_stream_list.begin(), xref_stm);
// SLOW ...
m_CrossRefTable = CPDF_CrossRefTable::MergeUp(
std::make_unique<CPDF_CrossRefTable>(std::move(pDict),
kNoV4TrailerObjectNumber),
std::move(m_CrossRefTable));
}
if (xref_stream_list[0] > 0 &&
!LoadCrossRefV5(&xref_stream_list[0], /*is_main_xref=*/false,
/*overwrite_existing=*/true)) {
return false;
}
// Traverse the xref data structures from oldest to newest. So entries from
// later iterations should overwrite existing entries.
for (size_t i = 1; i < xref_list.size(); ++i) {
if (xref_list[i] > 0 && !LoadCrossRefV4(xref_list[i], false))
return false;
if (xref_stream_list[i] > 0 &&
!LoadCrossRefV5(&xref_stream_list[i], /*is_main_xref=*/false,
/*overwrite_existing=*/true)) {
return false;
}
}
return true;
}
bool CPDF_Parser::ParseAndAppendCrossRefSubsectionData(
uint32_t start_objnum,
uint32_t count,
std::vector<CrossRefObjData>* out_objects) {
if (!count)
return true;
// Each entry shall be exactly 20 byte.
// A sample entry looks like:
// "0000000000 00007 f\r\n"
static constexpr int32_t kEntrySize = 20;
if (!out_objects) {
FX_SAFE_FILESIZE pos = count;
pos *= kEntrySize;
pos += m_pSyntax->GetPos();
if (!pos.IsValid())
return false;
m_pSyntax->SetPos(pos.ValueOrDie());
return true;
}
const size_t start_obj_index = out_objects->size();
FX_SAFE_SIZE_T new_size = start_obj_index;
new_size += count;
if (!new_size.IsValid())
return false;
if (new_size.ValueOrDie() > kMaxXRefSize)
return false;
const size_t max_entries_in_file = m_pSyntax->GetDocumentSize() / kEntrySize;
if (new_size.ValueOrDie() > max_entries_in_file)
return false;
out_objects->resize(new_size.ValueOrDie());
DataVector<char> buf(1024 * kEntrySize + 1);
buf.back() = '\0';
uint32_t entries_to_read = count;
while (entries_to_read > 0) {
const uint32_t entries_in_block = std::min(entries_to_read, 1024u);
const uint32_t bytes_to_read = entries_in_block * kEntrySize;
auto block_span = pdfium::make_span(buf).first(bytes_to_read);
if (!m_pSyntax->ReadBlock(pdfium::as_writable_bytes(block_span)))
return false;
for (uint32_t i = 0; i < entries_in_block; i++) {
uint32_t iObjectIndex = count - entries_to_read + i;
CrossRefObjData& obj_data =
(*out_objects)[start_obj_index + iObjectIndex];
const uint32_t objnum = start_objnum + iObjectIndex;
obj_data.obj_num = objnum;
ObjectInfo& info = obj_data.info;
const char* pEntry = &buf[i * kEntrySize];
if (pEntry[17] == 'f') {
info.pos = 0;
info.type = ObjectType::kFree;
} else {
const FX_SAFE_FILESIZE offset = FXSYS_atoi64(pEntry);
if (!offset.IsValid())
return false;
if (offset.ValueOrDie() == 0) {
for (int32_t c = 0; c < 10; c++) {
if (!isdigit(pEntry[c]))
return false;
}
}
info.pos = offset.ValueOrDie();
// TODO(art-snake): The info.gennum is uint16_t, but version may be
// greated than max<uint16_t>. Needs solve this issue.
const int32_t version = FXSYS_atoi(pEntry + 11);
info.gennum = version;
info.type = ObjectType::kNormal;
}
}
entries_to_read -= entries_in_block;
}
return true;
}
bool CPDF_Parser::ParseCrossRefV4(std::vector<CrossRefObjData>* out_objects) {
if (out_objects)
out_objects->clear();
if (m_pSyntax->GetKeyword() != "xref")
return false;
std::vector<CrossRefObjData> result_objects;
while (true) {
FX_FILESIZE saved_pos = m_pSyntax->GetPos();
CPDF_SyntaxParser::WordResult word_result = m_pSyntax->GetNextWord();
const ByteString& word = word_result.word;
if (word.IsEmpty())
return false;
if (!word_result.is_number) {
m_pSyntax->SetPos(saved_pos);
break;
}
uint32_t start_objnum = FXSYS_atoui(word.c_str());
if (start_objnum >= kMaxObjectNumber)
return false;
uint32_t count = m_pSyntax->GetDirectNum();
m_pSyntax->ToNextWord();
if (!ParseAndAppendCrossRefSubsectionData(
start_objnum, count, out_objects ? &result_objects : nullptr)) {
return false;
}
}
if (out_objects)
*out_objects = std::move(result_objects);
return true;
}
bool CPDF_Parser::LoadCrossRefV4(FX_FILESIZE pos, bool bSkip) {
m_pSyntax->SetPos(pos);
std::vector<CrossRefObjData> objects;
if (!ParseCrossRefV4(bSkip ? nullptr : &objects))
return false;
MergeCrossRefObjectsData(objects);
return true;
}
void CPDF_Parser::MergeCrossRefObjectsData(
const std::vector<CrossRefObjData>& objects) {
for (const auto& obj : objects) {
switch (obj.info.type) {
case ObjectType::kFree:
if (obj.info.gennum > 0)
m_CrossRefTable->SetFree(obj.obj_num);
break;
case ObjectType::kNormal:
case ObjectType::kObjStream:
m_CrossRefTable->AddNormal(obj.obj_num, obj.info.gennum, obj.info.pos);
break;
case ObjectType::kCompressed:
m_CrossRefTable->AddCompressed(obj.obj_num, obj.info.archive.obj_num,
obj.info.archive.obj_index);
break;
}
}
}
bool CPDF_Parser::LoadAllCrossRefV5(FX_FILESIZE xref_offset) {
if (!LoadCrossRefV5(&xref_offset, /*is_main_xref=*/true,
/*overwrite_existing=*/false)) {
return false;
}
// Traverse the xref objects from newest to older. So entries from later
// iterations should not overwrite existing entries.
std::set<FX_FILESIZE> seen_xref_offset;
while (xref_offset > 0) {
seen_xref_offset.insert(xref_offset);
if (!LoadCrossRefV5(&xref_offset, /*is_main_xref=*/false,
/*overwrite_existing=*/false)) {
return false;
}
// Check for circular references.
if (pdfium::Contains(seen_xref_offset, xref_offset))
return false;
}
m_ObjectStreamMap.clear();
m_bXRefStream = true;
return true;
}
bool CPDF_Parser::RebuildCrossRef() {
auto cross_ref_table = std::make_unique<CPDF_CrossRefTable>();
const uint32_t kBufferSize = 4096;
m_pSyntax->SetReadBufferSize(kBufferSize);
m_pSyntax->SetPos(0);
std::vector<std::pair<uint32_t, FX_FILESIZE>> numbers;
for (CPDF_SyntaxParser::WordResult result = m_pSyntax->GetNextWord();
!result.word.IsEmpty(); result = m_pSyntax->GetNextWord()) {
const ByteString& word = result.word;
if (result.is_number) {
numbers.emplace_back(FXSYS_atoui(word.c_str()),
m_pSyntax->GetPos() - word.GetLength());
if (numbers.size() > 2u)
numbers.erase(numbers.begin());
continue;
}
if (word == "(") {
m_pSyntax->ReadString();
} else if (word == "<") {
m_pSyntax->ReadHexString();
} else if (word == "trailer") {
RetainPtr<CPDF_Object> pTrailer = m_pSyntax->GetObjectBody(nullptr);
if (pTrailer) {
CPDF_Stream* stream_trailer = pTrailer->AsMutableStream();
// Grab the object number from `pTrailer` before potentially calling
// std::move(pTrailer) below.
const uint32_t trailer_object_number = pTrailer->GetObjNum();
RetainPtr<CPDF_Dictionary> trailer_dict =
stream_trailer ? stream_trailer->GetMutableDict()
: ToDictionary(std::move(pTrailer));
cross_ref_table = CPDF_CrossRefTable::MergeUp(
std::move(cross_ref_table),
std::make_unique<CPDF_CrossRefTable>(std::move(trailer_dict),
trailer_object_number));
}
} else if (word == "obj" && numbers.size() == 2u) {
const FX_FILESIZE obj_pos = numbers[0].second;
const uint32_t obj_num = numbers[0].first;
const uint32_t gen_num = numbers[1].first;
m_pSyntax->SetPos(obj_pos);
const RetainPtr<CPDF_Stream> pStream =
ToStream(m_pSyntax->GetIndirectObject(
nullptr, CPDF_SyntaxParser::ParseType::kStrict));
if (pStream && pStream->GetDict()->GetNameFor("Type") == "XRef") {
cross_ref_table = CPDF_CrossRefTable::MergeUp(
std::move(cross_ref_table),
std::make_unique<CPDF_CrossRefTable>(
ToDictionary(pStream->GetDict()->Clone()),
pStream->GetObjNum()));
}
if (obj_num < kMaxObjectNumber) {
cross_ref_table->AddNormal(obj_num, gen_num, obj_pos);
const auto object_stream =
CPDF_ObjectStream::Create(std::move(pStream));
if (object_stream) {
const auto& object_info = object_stream->object_info();
for (size_t i = 0; i < object_info.size(); ++i) {
const auto& info = object_info[i];
if (info.obj_num < kMaxObjectNumber)
cross_ref_table->AddCompressed(info.obj_num, obj_num, i);
}
}
}
}
numbers.clear();
}
m_CrossRefTable = CPDF_CrossRefTable::MergeUp(std::move(m_CrossRefTable),
std::move(cross_ref_table));
// Resore default buffer size.
m_pSyntax->SetReadBufferSize(CPDF_Stream::kFileBufSize);
return GetTrailer() && !m_CrossRefTable->objects_info().empty();
}
bool CPDF_Parser::LoadCrossRefV5(FX_FILESIZE* pos,
bool is_main_xref,
bool overwrite_existing) {
RetainPtr<const CPDF_Stream> pStream =
ToStream(ParseIndirectObjectAt(*pos, 0));
if (!pStream || !pStream->GetObjNum()) {
return false;
}
RetainPtr<const CPDF_Dictionary> pDict = pStream->GetDict();
int32_t prev = pDict->GetIntegerFor("Prev");
if (prev < 0)
return false;
int32_t size = pDict->GetIntegerFor("Size");
if (size < 0)
return false;
*pos = prev;
auto new_cross_ref_table = std::make_unique<CPDF_CrossRefTable>(
/*trailer=*/ToDictionary(pDict->Clone()),
/*trailer_object_number=*/pStream->GetObjNum());
if (is_main_xref) {
m_CrossRefTable = std::move(new_cross_ref_table);
m_CrossRefTable->SetObjectMapSize(size);
} else {
m_CrossRefTable = CPDF_CrossRefTable::MergeUp(
std::move(new_cross_ref_table), std::move(m_CrossRefTable));
}
std::vector<CrossRefV5IndexEntry> indices =
GetCrossRefV5Indices(pDict->GetArrayFor("Index").Get(), size);
std::vector<uint32_t> field_widths =
GetFieldWidths(pDict->GetArrayFor("W").Get());
if (field_widths.size() < kMinFieldCount)
return false;
FX_SAFE_UINT32 dwAccWidth;
for (uint32_t width : field_widths)
dwAccWidth += width;
if (!dwAccWidth.IsValid())
return false;
uint32_t total_width = dwAccWidth.ValueOrDie();
auto pAcc = pdfium::MakeRetain<CPDF_StreamAcc>(pStream);
pAcc->LoadAllDataFiltered();
pdfium::span<const uint8_t> data_span = pAcc->GetSpan();
uint32_t segindex = 0;
for (const auto& index : indices) {
FX_SAFE_UINT32 seg_end = segindex;
seg_end += index.obj_count;
seg_end *= total_width;
if (!seg_end.IsValid() || seg_end.ValueOrDie() > data_span.size())
continue;
pdfium::span<const uint8_t> seg_span = data_span.subspan(
segindex * total_width, index.obj_count * total_width);
FX_SAFE_UINT32 safe_new_size = index.start_obj_num;
safe_new_size += index.obj_count;
if (!safe_new_size.IsValid()) {
continue;
}
// Until SetObjectMapSize() below has been called by a prior loop iteration,
// `current_size` is based on the /Size value parsed in LoadCrossRefV5().
// PDFs may not always have the correct /Size. In this case, other PDF
// implementations ignore the incorrect size, and PDFium also ignores
// incorrect size in trailers for V4 xrefs.
const uint32_t current_size =
m_CrossRefTable->objects_info().empty() ? 0 : GetLastObjNum() + 1;
// So allow `new_size` to be greater than `current_size`, but avoid going
// over `kMaxXRefSize`. This works just fine because the loop below checks
// against `kMaxObjectNumber`, and the two "max" constants are in sync.
const uint32_t new_size =
std::min<uint32_t>(safe_new_size.ValueOrDie(), kMaxXRefSize);
if (new_size > current_size) {
m_CrossRefTable->SetObjectMapSize(new_size);
}
for (uint32_t i = 0; i < index.obj_count; ++i) {
const uint32_t obj_num = index.start_obj_num + i;
if (obj_num >= kMaxObjectNumber) {
break;
}
ProcessCrossRefV5Entry(seg_span.subspan(i * total_width, total_width),
field_widths, obj_num, overwrite_existing);
}
segindex += index.obj_count;
}
return true;
}
void CPDF_Parser::ProcessCrossRefV5Entry(
pdfium::span<const uint8_t> entry_span,
pdfium::span<const uint32_t> field_widths,
uint32_t obj_num,
bool overwrite_existing) {
DCHECK_GE(field_widths.size(), kMinFieldCount);
ObjectType type;
if (field_widths[0]) {
const uint32_t cross_ref_stream_obj_type =
GetFirstXRefStreamEntry(entry_span, field_widths);
type = GetObjectTypeFromCrossRefStreamType(cross_ref_stream_obj_type);
if (type == ObjectType::kNull)
return;
} else {
// Per ISO 32000-1:2008 table 17, use the default value of 1 for the xref
// stream entry when it is not specified. The `type` assignment is the
// equivalent to calling GetObjectTypeFromCrossRefStreamType(1).
type = ObjectType::kNormal;
}
const ObjectType existing_type = GetObjectType(obj_num);
if (existing_type == ObjectType::kNull) {
const uint32_t offset = GetSecondXRefStreamEntry(entry_span, field_widths);
if (pdfium::base::IsValueInRangeForNumericType<FX_FILESIZE>(offset))
m_CrossRefTable->AddNormal(obj_num, 0, offset);
return;
}
if (!overwrite_existing && existing_type != ObjectType::kFree) {
return;
}
if (type == ObjectType::kFree) {
m_CrossRefTable->SetFree(obj_num);
return;
}
if (type == ObjectType::kNormal) {
const uint32_t offset = GetSecondXRefStreamEntry(entry_span, field_widths);
if (pdfium::base::IsValueInRangeForNumericType<FX_FILESIZE>(offset))
m_CrossRefTable->AddNormal(obj_num, 0, offset);
return;
}
DCHECK_EQ(type, ObjectType::kCompressed);
const uint32_t archive_obj_num =
GetSecondXRefStreamEntry(entry_span, field_widths);
if (!IsValidObjectNumber(archive_obj_num)) {
return;
}
const uint32_t archive_obj_index =
GetThirdXRefStreamEntry(entry_span, field_widths);
m_CrossRefTable->AddCompressed(obj_num, archive_obj_num, archive_obj_index);
}
RetainPtr<const CPDF_Array> CPDF_Parser::GetIDArray() const {
return GetTrailer() ? GetTrailer()->GetArrayFor("ID") : nullptr;
}
RetainPtr<const CPDF_Dictionary> CPDF_Parser::GetRoot() const {
RetainPtr<CPDF_Object> obj =
m_pObjectsHolder->GetOrParseIndirectObject(GetRootObjNum());
return obj ? obj->GetDict() : nullptr;
}
RetainPtr<const CPDF_Dictionary> CPDF_Parser::GetEncryptDict() const {
if (!GetTrailer())
return nullptr;
RetainPtr<const CPDF_Object> pEncryptObj =
GetTrailer()->GetObjectFor("Encrypt");
if (!pEncryptObj)
return nullptr;
if (pEncryptObj->IsDictionary())
return pdfium::WrapRetain(pEncryptObj->AsDictionary());
if (pEncryptObj->IsReference()) {
return ToDictionary(m_pObjectsHolder->GetOrParseIndirectObject(
pEncryptObj->AsReference()->GetRefObjNum()));
}
return nullptr;
}
ByteString CPDF_Parser::GetEncodedPassword() const {
return GetSecurityHandler()->GetEncodedPassword(GetPassword().AsStringView());
}
const CPDF_Dictionary* CPDF_Parser::GetTrailer() const {
return m_CrossRefTable->trailer();
}
CPDF_Dictionary* CPDF_Parser::GetMutableTrailerForTesting() {
return m_CrossRefTable->GetMutableTrailerForTesting();
}
uint32_t CPDF_Parser::GetTrailerObjectNumber() const {
return m_CrossRefTable->trailer_object_number();
}
RetainPtr<CPDF_Dictionary> CPDF_Parser::GetCombinedTrailer() const {
return m_CrossRefTable->trailer()
? ToDictionary(m_CrossRefTable->trailer()->Clone())
: RetainPtr<CPDF_Dictionary>();
}
uint32_t CPDF_Parser::GetInfoObjNum() const {
RetainPtr<const CPDF_Reference> pRef =
ToReference(m_CrossRefTable->trailer()
? m_CrossRefTable->trailer()->GetObjectFor("Info")
: nullptr);
return pRef ? pRef->GetRefObjNum() : CPDF_Object::kInvalidObjNum;
}
uint32_t CPDF_Parser::GetRootObjNum() const {
RetainPtr<const CPDF_Reference> pRef =
ToReference(m_CrossRefTable->trailer()
? m_CrossRefTable->trailer()->GetObjectFor("Root")
: nullptr);
return pRef ? pRef->GetRefObjNum() : CPDF_Object::kInvalidObjNum;
}
RetainPtr<CPDF_Object> CPDF_Parser::ParseIndirectObject(uint32_t objnum) {
if (!IsValidObjectNumber(objnum))
return nullptr;
// Prevent circular parsing the same object.
if (pdfium::Contains(m_ParsingObjNums, objnum))
return nullptr;
ScopedSetInsertion<uint32_t> local_insert(&m_ParsingObjNums, objnum);
if (GetObjectType(objnum) == ObjectType::kNormal) {
FX_FILESIZE pos = GetObjectPositionOrZero(objnum);
if (pos <= 0)
return nullptr;
return ParseIndirectObjectAt(pos, objnum);
}
if (GetObjectType(objnum) != ObjectType::kCompressed)
return nullptr;
const ObjectInfo& info = *m_CrossRefTable->GetObjectInfo(objnum);
const CPDF_ObjectStream* pObjStream = GetObjectStream(info.archive.obj_num);
if (!pObjStream)
return nullptr;
return pObjStream->ParseObject(m_pObjectsHolder, objnum,
info.archive.obj_index);
}
const CPDF_ObjectStream* CPDF_Parser::GetObjectStream(uint32_t object_number) {
// Prevent circular parsing the same object.
if (pdfium::Contains(m_ParsingObjNums, object_number))
return nullptr;
auto it = m_ObjectStreamMap.find(object_number);
if (it != m_ObjectStreamMap.end())
return it->second.get();
const auto* info = m_CrossRefTable->GetObjectInfo(object_number);
if (!info || info->type != ObjectType::kObjStream)
return nullptr;
const FX_FILESIZE object_pos = info->pos;
if (object_pos <= 0)
return nullptr;
// Keep track of `object_number` before doing more parsing.
ScopedSetInsertion<uint32_t> local_insert(&m_ParsingObjNums, object_number);
RetainPtr<CPDF_Object> object =
ParseIndirectObjectAt(object_pos, object_number);
if (!object)
return nullptr;
std::unique_ptr<CPDF_ObjectStream> objs_stream =
CPDF_ObjectStream::Create(ToStream(object));
const CPDF_ObjectStream* result = objs_stream.get();
m_ObjectStreamMap[object_number] = std::move(objs_stream);
return result;
}
RetainPtr<CPDF_Object> CPDF_Parser::ParseIndirectObjectAt(FX_FILESIZE pos,
uint32_t objnum) {
const FX_FILESIZE saved_pos = m_pSyntax->GetPos();
m_pSyntax->SetPos(pos);
auto result = m_pSyntax->GetIndirectObject(
m_pObjectsHolder, CPDF_SyntaxParser::ParseType::kLoose);
m_pSyntax->SetPos(saved_pos);
if (result && objnum && result->GetObjNum() != objnum)
return nullptr;
const bool should_decrypt = m_pSecurityHandler &&
m_pSecurityHandler->GetCryptoHandler() &&
objnum != m_MetadataObjnum;
if (should_decrypt &&
!m_pSecurityHandler->GetCryptoHandler()->DecryptObjectTree(result)) {
return nullptr;
}
return result;
}
FX_FILESIZE CPDF_Parser::GetDocumentSize() const {
return m_pSyntax->GetDocumentSize();
}
uint32_t CPDF_Parser::GetFirstPageNo() const {
return m_pLinearized ? m_pLinearized->GetFirstPageNo() : 0;
}
void CPDF_Parser::SetLinearizedHeaderForTesting(
std::unique_ptr<CPDF_LinearizedHeader> pLinearized) {
m_pLinearized = std::move(pLinearized);
}
RetainPtr<CPDF_Dictionary> CPDF_Parser::LoadTrailerV4() {
if (m_pSyntax->GetKeyword() != "trailer")
return nullptr;
return ToDictionary(m_pSyntax->GetObjectBody(m_pObjectsHolder));
}
uint32_t CPDF_Parser::GetPermissions(bool get_owner_perms) const {
return m_pSecurityHandler
? m_pSecurityHandler->GetPermissions(get_owner_perms)
: 0xFFFFFFFF;
}
std::unique_ptr<CPDF_LinearizedHeader> CPDF_Parser::ParseLinearizedHeader() {
return CPDF_LinearizedHeader::Parse(m_pSyntax.get());
}
CPDF_Parser::Error CPDF_Parser::StartLinearizedParse(
RetainPtr<CPDF_ReadValidator> validator,
const ByteString& password) {
DCHECK(!m_bHasParsed);
DCHECK(!m_bXRefTableRebuilt);
SetPassword(password);
m_bXRefStream = false;
m_LastXRefOffset = 0;
if (!InitSyntaxParser(std::move(validator)))
return FORMAT_ERROR;
m_pLinearized = ParseLinearizedHeader();
if (!m_pLinearized)
return StartParseInternal();
m_bHasParsed = true;
m_LastXRefOffset = m_pLinearized->GetLastXRefOffset();
FX_FILESIZE dwFirstXRefOffset = m_LastXRefOffset;
bool bLoadV4 = LoadCrossRefV4(dwFirstXRefOffset, false);
if (!bLoadV4 && !LoadCrossRefV5(&dwFirstXRefOffset, /*is_main_xref=*/true,
/*overwrite_existing=*/false)) {
if (!RebuildCrossRef())
return FORMAT_ERROR;
m_bXRefTableRebuilt = true;
m_LastXRefOffset = 0;
}
if (bLoadV4) {
RetainPtr<CPDF_Dictionary> trailer = LoadTrailerV4();
if (!trailer)
return SUCCESS;
m_CrossRefTable->SetTrailer(std::move(trailer), kNoV4TrailerObjectNumber);
const int32_t xrefsize = GetTrailer()->GetDirectIntegerFor("Size");
if (xrefsize > 0) {
// Check if `xrefsize` is correct. If it is incorrect, give up and rebuild
// the xref table.
const uint32_t expected_last_obj_num = xrefsize - 1;
if (GetLastObjNum() != expected_last_obj_num && !RebuildCrossRef()) {
return FORMAT_ERROR;
}
}
}
Error eRet = SetEncryptHandler();
if (eRet != SUCCESS)
return eRet;
if (!GetRoot() || !m_pObjectsHolder->TryInit()) {
if (m_bXRefTableRebuilt)
return FORMAT_ERROR;
ReleaseEncryptHandler();
if (!RebuildCrossRef())
return FORMAT_ERROR;
eRet = SetEncryptHandler();
if (eRet != SUCCESS)
return eRet;
m_pObjectsHolder->TryInit();
if (!GetRoot())
return FORMAT_ERROR;
}
if (GetRootObjNum() == CPDF_Object::kInvalidObjNum) {
ReleaseEncryptHandler();
if (!RebuildCrossRef() || GetRootObjNum() == CPDF_Object::kInvalidObjNum)
return FORMAT_ERROR;
eRet = SetEncryptHandler();
if (eRet != SUCCESS)
return eRet;
}
if (m_pSecurityHandler && m_pSecurityHandler->IsMetadataEncrypted()) {
RetainPtr<const CPDF_Reference> pMetadata =
ToReference(GetRoot()->GetObjectFor("Metadata"));
if (pMetadata)
m_MetadataObjnum = pMetadata->GetRefObjNum();
}
return SUCCESS;
}
bool CPDF_Parser::LoadLinearizedAllCrossRefV5(FX_FILESIZE main_xref_offset) {
FX_FILESIZE xref_offset = main_xref_offset;
if (!LoadCrossRefV5(&xref_offset, /*is_main_xref=*/false,
/*overwrite_existing=*/false)) {
return false;
}
// Traverse the xref objects from newest to older. So entries from later
// iterations should not overwrite existing entries.
std::set<FX_FILESIZE> seen_xref_offset;
while (xref_offset) {
seen_xref_offset.insert(xref_offset);
if (!LoadCrossRefV5(&xref_offset, /*is_main_xref=*/false,
/*overwrite_existing=*/false)) {
return false;
}
// Check for circular references.
if (pdfium::Contains(seen_xref_offset, xref_offset))
return false;
}
m_ObjectStreamMap.clear();
m_bXRefStream = true;
return true;
}
CPDF_Parser::Error CPDF_Parser::LoadLinearizedMainXRefTable() {
const FX_SAFE_FILESIZE prev = GetTrailer()->GetIntegerFor("Prev");
const FX_FILESIZE main_xref_offset = prev.ValueOrDefault(-1);
if (main_xref_offset < 0)
return FORMAT_ERROR;
if (main_xref_offset == 0)
return SUCCESS;
const AutoRestorer<uint32_t> save_metadata_objnum(&m_MetadataObjnum);
m_MetadataObjnum = 0;
m_ObjectStreamMap.clear();
if (!LoadLinearizedAllCrossRefV4(main_xref_offset) &&
!LoadLinearizedAllCrossRefV5(main_xref_offset)) {
m_LastXRefOffset = 0;
return FORMAT_ERROR;
}
return SUCCESS;
}
void CPDF_Parser::SetSyntaxParserForTesting(
std::unique_ptr<CPDF_SyntaxParser> parser) {
m_pSyntax = std::move(parser);
}
std::vector<unsigned int> CPDF_Parser::GetTrailerEnds() {
std::vector<unsigned int> trailer_ends;
m_pSyntax->SetTrailerEnds(&trailer_ends);
// Traverse the document.
m_pSyntax->SetPos(0);
while (true) {
CPDF_SyntaxParser::WordResult word_result = m_pSyntax->GetNextWord();
if (word_result.is_number) {
// The object number was read. Read the generation number.
word_result = m_pSyntax->GetNextWord();
if (!word_result.is_number)
break;
word_result = m_pSyntax->GetNextWord();
if (word_result.word != "obj")
break;
m_pSyntax->GetObjectBody(nullptr);
word_result = m_pSyntax->GetNextWord();
if (word_result.word != "endobj")
break;
} else if (word_result.word == "trailer") {
m_pSyntax->GetObjectBody(nullptr);
} else if (word_result.word == "startxref") {
m_pSyntax->GetNextWord();
} else if (word_result.word == "xref") {
while (true) {
word_result = m_pSyntax->GetNextWord();
if (word_result.word.IsEmpty() || word_result.word == "startxref")
break;
}
m_pSyntax->GetNextWord();
} else {
break;
}
}
// Stop recording trailer ends.
m_pSyntax->SetTrailerEnds(nullptr);
return trailer_ends;
}
bool CPDF_Parser::WriteToArchive(IFX_ArchiveStream* archive,
FX_FILESIZE src_size) {
static constexpr FX_FILESIZE kBufferSize = 4096;
DataVector<uint8_t> buffer(kBufferSize);
m_pSyntax->SetPos(0);
while (src_size) {
const uint32_t block_size =
static_cast<uint32_t>(std::min(kBufferSize, src_size));
auto block_span = pdfium::make_span(buffer).first(block_size);
if (!m_pSyntax->ReadBlock(block_span))
return false;
if (!archive->WriteBlock(pdfium::make_span(buffer).first(block_size)))
return false;
src_size -= block_size;
}
return true;
}