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      1 // Copyright 2014 PDFium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
      6 
      7 #include "core/fpdfapi/edit/cpdf_creator.h"
      8 
      9 #include <algorithm>
     10 
     11 #include "core/fpdfapi/edit/cpdf_encryptor.h"
     12 #include "core/fpdfapi/edit/cpdf_flateencoder.h"
     13 #include "core/fpdfapi/parser/cpdf_array.h"
     14 #include "core/fpdfapi/parser/cpdf_crypto_handler.h"
     15 #include "core/fpdfapi/parser/cpdf_document.h"
     16 #include "core/fpdfapi/parser/cpdf_number.h"
     17 #include "core/fpdfapi/parser/cpdf_parser.h"
     18 #include "core/fpdfapi/parser/cpdf_security_handler.h"
     19 #include "core/fpdfapi/parser/cpdf_string.h"
     20 #include "core/fpdfapi/parser/fpdf_parser_decode.h"
     21 #include "core/fxcrt/fx_extension.h"
     22 #include "core/fxcrt/fx_random.h"
     23 
     24 namespace {
     25 
     26 const size_t kArchiveBufferSize = 32768;
     27 
     28 class CFX_FileBufferArchive : public IFX_ArchiveStream {
     29  public:
     30   explicit CFX_FileBufferArchive(const RetainPtr<IFX_WriteStream>& archive);
     31   ~CFX_FileBufferArchive() override;
     32 
     33   bool WriteBlock(const void* pBuf, size_t size) override;
     34   bool WriteByte(uint8_t byte) override;
     35   bool WriteDWord(uint32_t i) override;
     36   bool WriteString(const ByteStringView& str) override;
     37 
     38   FX_FILESIZE CurrentOffset() const override { return offset_; }
     39 
     40  private:
     41   bool Flush();
     42 
     43   FX_FILESIZE offset_;
     44   size_t current_length_;
     45   std::vector<uint8_t> buffer_;
     46   RetainPtr<IFX_WriteStream> backing_file_;
     47 };
     48 
     49 CFX_FileBufferArchive::CFX_FileBufferArchive(
     50     const RetainPtr<IFX_WriteStream>& file)
     51     : offset_(0),
     52       current_length_(0),
     53       buffer_(kArchiveBufferSize),
     54       backing_file_(file) {
     55   ASSERT(file);
     56 }
     57 
     58 CFX_FileBufferArchive::~CFX_FileBufferArchive() {
     59   Flush();
     60 }
     61 
     62 bool CFX_FileBufferArchive::Flush() {
     63   size_t nRemaining = current_length_;
     64   current_length_ = 0;
     65   if (!backing_file_)
     66     return false;
     67   if (!nRemaining)
     68     return true;
     69   return backing_file_->WriteBlock(buffer_.data(), nRemaining);
     70 }
     71 
     72 bool CFX_FileBufferArchive::WriteBlock(const void* pBuf, size_t size) {
     73   ASSERT(pBuf && size > 0);
     74 
     75   const uint8_t* buffer = reinterpret_cast<const uint8_t*>(pBuf);
     76   size_t temp_size = size;
     77   while (temp_size) {
     78     size_t buf_size = std::min(kArchiveBufferSize - current_length_, temp_size);
     79     memcpy(buffer_.data() + current_length_, buffer, buf_size);
     80 
     81     current_length_ += buf_size;
     82     if (current_length_ == kArchiveBufferSize && !Flush())
     83       return false;
     84 
     85     temp_size -= buf_size;
     86     buffer += buf_size;
     87   }
     88 
     89   pdfium::base::CheckedNumeric<FX_FILESIZE> safe_offset = offset_;
     90   safe_offset += size;
     91   if (!safe_offset.IsValid())
     92     return false;
     93 
     94   offset_ = safe_offset.ValueOrDie();
     95   return true;
     96 }
     97 
     98 bool CFX_FileBufferArchive::WriteByte(uint8_t byte) {
     99   return WriteBlock(&byte, 1);
    100 }
    101 
    102 bool CFX_FileBufferArchive::WriteDWord(uint32_t i) {
    103   char buf[32];
    104   FXSYS_itoa(i, buf, 10);
    105   return WriteBlock(buf, strlen(buf));
    106 }
    107 
    108 bool CFX_FileBufferArchive::WriteString(const ByteStringView& str) {
    109   return WriteBlock(str.raw_str(), str.GetLength());
    110 }
    111 
    112 std::vector<uint8_t> GenerateFileID(uint32_t dwSeed1, uint32_t dwSeed2) {
    113   std::vector<uint8_t> buffer(sizeof(uint32_t) * 4);
    114   uint32_t* pBuffer = reinterpret_cast<uint32_t*>(buffer.data());
    115   void* pContext = FX_Random_MT_Start(dwSeed1);
    116   for (int i = 0; i < 2; ++i)
    117     *pBuffer++ = FX_Random_MT_Generate(pContext);
    118 
    119   FX_Random_MT_Close(pContext);
    120   pContext = FX_Random_MT_Start(dwSeed2);
    121   for (int i = 0; i < 2; ++i)
    122     *pBuffer++ = FX_Random_MT_Generate(pContext);
    123 
    124   FX_Random_MT_Close(pContext);
    125   return buffer;
    126 }
    127 
    128 int32_t OutputIndex(IFX_ArchiveStream* archive, FX_FILESIZE offset) {
    129   if (!archive->WriteByte(static_cast<uint8_t>(offset >> 24)) ||
    130       !archive->WriteByte(static_cast<uint8_t>(offset >> 16)) ||
    131       !archive->WriteByte(static_cast<uint8_t>(offset >> 8)) ||
    132       !archive->WriteByte(static_cast<uint8_t>(offset)) ||
    133       !archive->WriteByte(0)) {
    134     return -1;
    135   }
    136   return 0;
    137 }
    138 
    139 }  // namespace
    140 
    141 CPDF_Creator::CPDF_Creator(CPDF_Document* pDoc,
    142                            const RetainPtr<IFX_WriteStream>& archive)
    143     : m_pDocument(pDoc),
    144       m_pParser(pDoc->GetParser()),
    145       m_bSecurityChanged(false),
    146       m_pEncryptDict(m_pParser ? m_pParser->GetEncryptDict() : nullptr),
    147       m_dwEncryptObjNum(0),
    148       m_pSecurityHandler(m_pParser ? m_pParser->GetSecurityHandler() : nullptr),
    149       m_pMetadata(nullptr),
    150       m_dwLastObjNum(m_pDocument->GetLastObjNum()),
    151       m_Archive(pdfium::MakeUnique<CFX_FileBufferArchive>(archive)),
    152       m_SavedOffset(0),
    153       m_iStage(-1),
    154       m_dwFlags(0),
    155       m_CurObjNum(0),
    156       m_XrefStart(0),
    157       m_pIDArray(nullptr),
    158       m_FileVersion(0) {}
    159 
    160 CPDF_Creator::~CPDF_Creator() {}
    161 
    162 bool CPDF_Creator::WriteStream(const CPDF_Object* pStream,
    163                                uint32_t objnum,
    164                                CPDF_CryptoHandler* pCrypto) {
    165   CPDF_FlateEncoder encoder(const_cast<CPDF_Stream*>(pStream->AsStream()),
    166                             pStream != m_pMetadata);
    167   CPDF_Encryptor encryptor(pCrypto, objnum, encoder.GetData(),
    168                            encoder.GetSize());
    169   if (static_cast<uint32_t>(encoder.GetDict()->GetIntegerFor("Length")) !=
    170       encryptor.GetSize()) {
    171     encoder.CloneDict();
    172     encoder.GetDict()->SetNewFor<CPDF_Number>(
    173         "Length", static_cast<int>(encryptor.GetSize()));
    174   }
    175 
    176   if (!WriteDirectObj(objnum, encoder.GetDict(), true) ||
    177       !m_Archive->WriteString("stream\r\n")) {
    178     return false;
    179   }
    180 
    181   // Allow for empty streams.
    182   if (encryptor.GetSize() > 0 &&
    183       !m_Archive->WriteBlock(encryptor.GetData(), encryptor.GetSize())) {
    184     return false;
    185   }
    186 
    187   return m_Archive->WriteString("\r\nendstream");
    188 }
    189 
    190 bool CPDF_Creator::WriteIndirectObj(uint32_t objnum, const CPDF_Object* pObj) {
    191   if (!m_Archive->WriteDWord(objnum) || !m_Archive->WriteString(" 0 obj\r\n"))
    192     return false;
    193 
    194   if (pObj->IsStream()) {
    195     CPDF_CryptoHandler* pHandler =
    196         pObj != m_pMetadata ? GetCryptoHandler() : nullptr;
    197     if (!WriteStream(pObj, objnum, pHandler))
    198       return false;
    199   } else if (!WriteDirectObj(objnum, pObj, true)) {
    200     return false;
    201   }
    202 
    203   return m_Archive->WriteString("\r\nendobj\r\n");
    204 }
    205 
    206 bool CPDF_Creator::WriteDirectObj(uint32_t objnum,
    207                                   const CPDF_Object* pObj,
    208                                   bool bEncrypt) {
    209   switch (pObj->GetType()) {
    210     case CPDF_Object::BOOLEAN:
    211     case CPDF_Object::NAME:
    212     case CPDF_Object::NULLOBJ:
    213     case CPDF_Object::NUMBER:
    214     case CPDF_Object::REFERENCE:
    215       if (!pObj->WriteTo(m_Archive.get()))
    216         return false;
    217       break;
    218 
    219     case CPDF_Object::STRING: {
    220       ByteString str = pObj->GetString();
    221       bool bHex = pObj->AsString()->IsHex();
    222       if (!GetCryptoHandler() || !bEncrypt) {
    223         if (!pObj->WriteTo(m_Archive.get()))
    224           return false;
    225         break;
    226       }
    227       CPDF_Encryptor encryptor(GetCryptoHandler(), objnum,
    228                                (uint8_t*)str.c_str(), str.GetLength());
    229       ByteString content = PDF_EncodeString(
    230           ByteString(encryptor.GetData(), encryptor.GetSize()), bHex);
    231       if (!m_Archive->WriteString(content.AsStringView()))
    232         return false;
    233       break;
    234     }
    235     case CPDF_Object::STREAM: {
    236       CPDF_FlateEncoder encoder(const_cast<CPDF_Stream*>(pObj->AsStream()),
    237                                 true);
    238       CPDF_Encryptor encryptor(GetCryptoHandler(), objnum, encoder.GetData(),
    239                                encoder.GetSize());
    240       if (static_cast<uint32_t>(encoder.GetDict()->GetIntegerFor("Length")) !=
    241           encryptor.GetSize()) {
    242         encoder.CloneDict();
    243         encoder.GetDict()->SetNewFor<CPDF_Number>(
    244             "Length", static_cast<int>(encryptor.GetSize()));
    245       }
    246       if (!WriteDirectObj(objnum, encoder.GetDict(), true) ||
    247           !m_Archive->WriteString("stream\r\n") ||
    248           !m_Archive->WriteBlock(encryptor.GetData(), encryptor.GetSize()) ||
    249           !m_Archive->WriteString("\r\nendstream")) {
    250         return false;
    251       }
    252 
    253       break;
    254     }
    255     case CPDF_Object::ARRAY: {
    256       if (!m_Archive->WriteString("["))
    257         return false;
    258 
    259       const CPDF_Array* p = pObj->AsArray();
    260       for (size_t i = 0; i < p->GetCount(); i++) {
    261         CPDF_Object* pElement = p->GetObjectAt(i);
    262         if (!pElement->IsInline()) {
    263           if (!m_Archive->WriteString(" ") ||
    264               !m_Archive->WriteDWord(pElement->GetObjNum()) ||
    265               !m_Archive->WriteString(" 0 R")) {
    266             return false;
    267           }
    268         } else if (!WriteDirectObj(objnum, pElement, true)) {
    269           return false;
    270         }
    271       }
    272       if (!m_Archive->WriteString("]"))
    273         return false;
    274       break;
    275     }
    276     case CPDF_Object::DICTIONARY: {
    277       if (!GetCryptoHandler() || pObj == m_pEncryptDict) {
    278         if (!pObj->WriteTo(m_Archive.get()))
    279           return false;
    280         break;
    281       }
    282 
    283       if (!m_Archive->WriteString("<<"))
    284         return false;
    285 
    286       const CPDF_Dictionary* p = pObj->AsDictionary();
    287       bool bSignDict = p->IsSignatureDict();
    288       for (const auto& it : *p) {
    289         bool bSignValue = false;
    290         const ByteString& key = it.first;
    291         CPDF_Object* pValue = it.second.get();
    292         if (!m_Archive->WriteString("/") ||
    293             !m_Archive->WriteString(PDF_NameEncode(key).AsStringView())) {
    294           return false;
    295         }
    296 
    297         if (bSignDict && key == "Contents")
    298           bSignValue = true;
    299         if (!pValue->IsInline()) {
    300           if (!m_Archive->WriteString(" ") ||
    301               !m_Archive->WriteDWord(pValue->GetObjNum()) ||
    302               !m_Archive->WriteString(" 0 R ")) {
    303             return false;
    304           }
    305         } else if (!WriteDirectObj(objnum, pValue, !bSignValue)) {
    306           return false;
    307         }
    308       }
    309       if (!m_Archive->WriteString(">>"))
    310         return false;
    311       break;
    312     }
    313   }
    314   return true;
    315 }
    316 
    317 bool CPDF_Creator::WriteOldIndirectObject(uint32_t objnum) {
    318   if (m_pParser->IsObjectFreeOrNull(objnum))
    319     return true;
    320 
    321   m_ObjectOffsets[objnum] = m_Archive->CurrentOffset();
    322 
    323   bool bExistInMap = !!m_pDocument->GetIndirectObject(objnum);
    324   CPDF_Object* pObj = m_pDocument->GetOrParseIndirectObject(objnum);
    325   if (!pObj) {
    326     m_ObjectOffsets.erase(objnum);
    327     return true;
    328   }
    329   if (!WriteIndirectObj(pObj->GetObjNum(), pObj))
    330     return false;
    331   if (!bExistInMap)
    332     m_pDocument->DeleteIndirectObject(objnum);
    333   return true;
    334 }
    335 
    336 bool CPDF_Creator::WriteOldObjs() {
    337   uint32_t nLastObjNum = m_pParser->GetLastObjNum();
    338   if (!m_pParser->IsValidObjectNumber(nLastObjNum))
    339     return true;
    340 
    341   for (uint32_t objnum = m_CurObjNum; objnum <= nLastObjNum; ++objnum) {
    342     if (!WriteOldIndirectObject(objnum))
    343       return false;
    344   }
    345   return true;
    346 }
    347 
    348 bool CPDF_Creator::WriteNewObjs() {
    349   for (size_t i = m_CurObjNum; i < m_NewObjNumArray.size(); ++i) {
    350     uint32_t objnum = m_NewObjNumArray[i];
    351     CPDF_Object* pObj = m_pDocument->GetIndirectObject(objnum);
    352     if (!pObj)
    353       continue;
    354 
    355     m_ObjectOffsets[objnum] = m_Archive->CurrentOffset();
    356     if (!WriteIndirectObj(pObj->GetObjNum(), pObj))
    357       return false;
    358   }
    359   return true;
    360 }
    361 
    362 void CPDF_Creator::InitOldObjNumOffsets() {
    363   if (!m_pParser)
    364     return;
    365 
    366   uint32_t dwStart = 0;
    367   uint32_t dwEnd = m_pParser->GetLastObjNum();
    368   while (dwStart <= dwEnd) {
    369     while (dwStart <= dwEnd && m_pParser->IsObjectFreeOrNull(dwStart))
    370       dwStart++;
    371 
    372     if (dwStart > dwEnd)
    373       break;
    374 
    375     uint32_t j = dwStart;
    376     while (j <= dwEnd && !m_pParser->IsObjectFreeOrNull(j))
    377       j++;
    378 
    379     dwStart = j;
    380   }
    381 }
    382 
    383 void CPDF_Creator::InitNewObjNumOffsets() {
    384   for (const auto& pair : *m_pDocument) {
    385     const uint32_t objnum = pair.first;
    386     if (IsIncremental() ||
    387         pair.second->GetObjNum() == CPDF_Object::kInvalidObjNum) {
    388       continue;
    389     }
    390     if (m_pParser && m_pParser->IsValidObjectNumber(objnum) &&
    391         !m_pParser->IsObjectFree(objnum)) {
    392       continue;
    393     }
    394     m_NewObjNumArray.insert(std::lower_bound(m_NewObjNumArray.begin(),
    395                                              m_NewObjNumArray.end(), objnum),
    396                             objnum);
    397   }
    398 }
    399 
    400 int32_t CPDF_Creator::WriteDoc_Stage1() {
    401   ASSERT(m_iStage > -1 || m_iStage < 20);
    402   if (m_iStage == 0) {
    403     if (!m_pParser)
    404       m_dwFlags &= ~FPDFCREATE_INCREMENTAL;
    405     if (m_bSecurityChanged && IsOriginal())
    406       m_dwFlags &= ~FPDFCREATE_INCREMENTAL;
    407 
    408     const CPDF_Dictionary* pDict = m_pDocument->GetRoot();
    409     m_pMetadata = pDict ? pDict->GetDirectObjectFor("Metadata") : nullptr;
    410     m_iStage = 10;
    411   }
    412   if (m_iStage == 10) {
    413     if (!IsIncremental()) {
    414       if (!m_Archive->WriteString("%PDF-1."))
    415         return -1;
    416 
    417       int32_t version = 7;
    418       if (m_FileVersion)
    419         version = m_FileVersion;
    420       else if (m_pParser)
    421         version = m_pParser->GetFileVersion();
    422 
    423       if (!m_Archive->WriteDWord(version % 10) ||
    424           !m_Archive->WriteString("\r\n%\xA1\xB3\xC5\xD7\r\n")) {
    425         return -1;
    426       }
    427 
    428       InitOldObjNumOffsets();
    429       m_iStage = 20;
    430     } else {
    431       m_SavedOffset = m_pParser->GetFileAccess()->GetSize();
    432       m_iStage = 15;
    433     }
    434   }
    435   if (m_iStage == 15) {
    436     if (IsOriginal() && m_SavedOffset > 0) {
    437       RetainPtr<IFX_SeekableReadStream> pSrcFile = m_pParser->GetFileAccess();
    438       std::vector<uint8_t> buffer(4096);
    439       FX_FILESIZE src_size = m_SavedOffset;
    440       while (src_size) {
    441         uint32_t block_size = src_size > 4096 ? 4096 : src_size;
    442         if (!pSrcFile->ReadBlock(buffer.data(),
    443                                  m_Archive->CurrentOffset() - src_size,
    444                                  block_size)) {
    445           return -1;
    446         }
    447         if (!m_Archive->WriteBlock(buffer.data(), block_size))
    448           return -1;
    449 
    450         src_size -= block_size;
    451       }
    452     }
    453     if (IsOriginal() && m_pParser->GetLastXRefOffset() == 0) {
    454       InitOldObjNumOffsets();
    455 
    456       for (uint32_t num = 0; num <= m_pParser->GetLastObjNum(); ++num) {
    457         if (m_pParser->IsObjectFreeOrNull(num))
    458           continue;
    459 
    460         m_ObjectOffsets[num] = m_pParser->GetObjectPositionOrZero(num);
    461       }
    462     }
    463     m_iStage = 20;
    464   }
    465   InitNewObjNumOffsets();
    466   return m_iStage;
    467 }
    468 
    469 int32_t CPDF_Creator::WriteDoc_Stage2() {
    470   ASSERT(m_iStage >= 20 || m_iStage < 30);
    471   if (m_iStage == 20) {
    472     if (!IsIncremental() && m_pParser) {
    473       m_CurObjNum = 0;
    474       m_iStage = 21;
    475     } else {
    476       m_iStage = 25;
    477     }
    478   }
    479   if (m_iStage == 21) {
    480     if (!WriteOldObjs())
    481       return -1;
    482 
    483     m_iStage = 25;
    484   }
    485   if (m_iStage == 25) {
    486     m_CurObjNum = 0;
    487     m_iStage = 26;
    488   }
    489   if (m_iStage == 26) {
    490     if (!WriteNewObjs())
    491       return -1;
    492 
    493     m_iStage = 27;
    494   }
    495   if (m_iStage == 27) {
    496     if (m_pEncryptDict && m_pEncryptDict->IsInline()) {
    497       m_dwLastObjNum += 1;
    498       FX_FILESIZE saveOffset = m_Archive->CurrentOffset();
    499       if (!WriteIndirectObj(m_dwLastObjNum, m_pEncryptDict.Get()))
    500         return -1;
    501 
    502       m_ObjectOffsets[m_dwLastObjNum] = saveOffset;
    503       m_dwEncryptObjNum = m_dwLastObjNum;
    504       if (IsIncremental())
    505         m_NewObjNumArray.push_back(m_dwLastObjNum);
    506     }
    507     m_iStage = 80;
    508   }
    509   return m_iStage;
    510 }
    511 
    512 int32_t CPDF_Creator::WriteDoc_Stage3() {
    513   ASSERT(m_iStage >= 80 || m_iStage < 90);
    514 
    515   uint32_t dwLastObjNum = m_dwLastObjNum;
    516   if (m_iStage == 80) {
    517     m_XrefStart = m_Archive->CurrentOffset();
    518     if (!IsIncremental() || !m_pParser->IsXRefStream()) {
    519       if (!IsIncremental() || m_pParser->GetLastXRefOffset() == 0) {
    520         ByteString str;
    521         str = pdfium::ContainsKey(m_ObjectOffsets, 1)
    522                   ? "xref\r\n"
    523                   : "xref\r\n0 1\r\n0000000000 65535 f\r\n";
    524         if (!m_Archive->WriteString(str.AsStringView()))
    525           return -1;
    526 
    527         m_CurObjNum = 1;
    528         m_iStage = 81;
    529       } else {
    530         if (!m_Archive->WriteString("xref\r\n"))
    531           return -1;
    532 
    533         m_CurObjNum = 0;
    534         m_iStage = 82;
    535       }
    536     } else {
    537       m_iStage = 90;
    538     }
    539   }
    540   if (m_iStage == 81) {
    541     ByteString str;
    542     uint32_t i = m_CurObjNum;
    543     uint32_t j;
    544     while (i <= dwLastObjNum) {
    545       while (i <= dwLastObjNum && !pdfium::ContainsKey(m_ObjectOffsets, i))
    546         i++;
    547 
    548       if (i > dwLastObjNum)
    549         break;
    550 
    551       j = i;
    552       while (j <= dwLastObjNum && pdfium::ContainsKey(m_ObjectOffsets, j))
    553         j++;
    554 
    555       if (i == 1)
    556         str = ByteString::Format("0 %d\r\n0000000000 65535 f\r\n", j);
    557       else
    558         str = ByteString::Format("%d %d\r\n", i, j - i);
    559 
    560       if (!m_Archive->WriteBlock(str.c_str(), str.GetLength()))
    561         return -1;
    562 
    563       while (i < j) {
    564         str = ByteString::Format("%010d 00000 n\r\n", m_ObjectOffsets[i++]);
    565         if (!m_Archive->WriteBlock(str.c_str(), str.GetLength()))
    566           return -1;
    567       }
    568       if (i > dwLastObjNum)
    569         break;
    570     }
    571     m_iStage = 90;
    572   }
    573   if (m_iStage == 82) {
    574     ByteString str;
    575     uint32_t iCount = pdfium::CollectionSize<uint32_t>(m_NewObjNumArray);
    576     uint32_t i = m_CurObjNum;
    577     while (i < iCount) {
    578       size_t j = i;
    579       uint32_t objnum = m_NewObjNumArray[i];
    580       while (j < iCount) {
    581         if (++j == iCount)
    582           break;
    583         uint32_t dwCurrent = m_NewObjNumArray[j];
    584         if (dwCurrent - objnum > 1)
    585           break;
    586         objnum = dwCurrent;
    587       }
    588       objnum = m_NewObjNumArray[i];
    589       if (objnum == 1)
    590         str = ByteString::Format("0 %d\r\n0000000000 65535 f\r\n", j - i + 1);
    591       else
    592         str = ByteString::Format("%d %d\r\n", objnum, j - i);
    593 
    594       if (!m_Archive->WriteBlock(str.c_str(), str.GetLength()))
    595         return -1;
    596 
    597       while (i < j) {
    598         objnum = m_NewObjNumArray[i++];
    599         str = ByteString::Format("%010d 00000 n\r\n", m_ObjectOffsets[objnum]);
    600         if (!m_Archive->WriteBlock(str.c_str(), str.GetLength()))
    601           return -1;
    602       }
    603     }
    604     m_iStage = 90;
    605   }
    606   return m_iStage;
    607 }
    608 
    609 int32_t CPDF_Creator::WriteDoc_Stage4() {
    610   ASSERT(m_iStage >= 90);
    611 
    612   bool bXRefStream = IsIncremental() && m_pParser->IsXRefStream();
    613   if (!bXRefStream) {
    614     if (!m_Archive->WriteString("trailer\r\n<<"))
    615       return -1;
    616   } else {
    617     if (!m_Archive->WriteDWord(m_pDocument->GetLastObjNum() + 1) ||
    618         !m_Archive->WriteString(" 0 obj <<")) {
    619       return -1;
    620     }
    621   }
    622 
    623   if (m_pParser) {
    624     std::unique_ptr<CPDF_Dictionary> p = m_pParser->GetCombinedTrailer();
    625     for (const auto& it : *p) {
    626       const ByteString& key = it.first;
    627       CPDF_Object* pValue = it.second.get();
    628       if (key == "Encrypt" || key == "Size" || key == "Filter" ||
    629           key == "Index" || key == "Length" || key == "Prev" || key == "W" ||
    630           key == "XRefStm" || key == "ID") {
    631         continue;
    632       }
    633       if (!m_Archive->WriteString(("/")) ||
    634           !m_Archive->WriteString(PDF_NameEncode(key).AsStringView())) {
    635         return -1;
    636       }
    637       if (!pValue->IsInline()) {
    638         if (!m_Archive->WriteString(" ") ||
    639             !m_Archive->WriteDWord(pValue->GetObjNum()) ||
    640             !m_Archive->WriteString(" 0 R ")) {
    641           return -1;
    642         }
    643       } else if (!pValue->WriteTo(m_Archive.get())) {
    644         return -1;
    645       }
    646     }
    647   } else {
    648     if (!m_Archive->WriteString("\r\n/Root ") ||
    649         !m_Archive->WriteDWord(m_pDocument->GetRoot()->GetObjNum()) ||
    650         !m_Archive->WriteString(" 0 R\r\n")) {
    651       return -1;
    652     }
    653     if (m_pDocument->GetInfo()) {
    654       if (!m_Archive->WriteString("/Info ") ||
    655           !m_Archive->WriteDWord(m_pDocument->GetInfo()->GetObjNum()) ||
    656           !m_Archive->WriteString(" 0 R\r\n")) {
    657         return -1;
    658       }
    659     }
    660   }
    661   if (m_pEncryptDict) {
    662     if (!m_Archive->WriteString("/Encrypt"))
    663       return -1;
    664 
    665     uint32_t dwObjNum = m_pEncryptDict->GetObjNum();
    666     if (dwObjNum == 0)
    667       dwObjNum = m_pDocument->GetLastObjNum() + 1;
    668     if (!m_Archive->WriteString(" ") || !m_Archive->WriteDWord(dwObjNum) ||
    669         !m_Archive->WriteString(" 0 R ")) {
    670       return -1;
    671     }
    672   }
    673 
    674   if (!m_Archive->WriteString("/Size ") ||
    675       !m_Archive->WriteDWord(m_dwLastObjNum + (bXRefStream ? 2 : 1))) {
    676     return -1;
    677   }
    678   if (IsIncremental()) {
    679     FX_FILESIZE prev = m_pParser->GetLastXRefOffset();
    680     if (prev) {
    681       if (!m_Archive->WriteString("/Prev "))
    682         return -1;
    683 
    684       char offset_buf[20];
    685       memset(offset_buf, 0, sizeof(offset_buf));
    686       FXSYS_i64toa(prev, offset_buf, 10);
    687       if (!m_Archive->WriteBlock(offset_buf, strlen(offset_buf)))
    688         return -1;
    689     }
    690   }
    691   if (m_pIDArray) {
    692     if (!m_Archive->WriteString(("/ID")) ||
    693         !m_pIDArray->WriteTo(m_Archive.get())) {
    694       return -1;
    695     }
    696   }
    697   if (!bXRefStream) {
    698     if (!m_Archive->WriteString(">>"))
    699       return -1;
    700   } else {
    701     if (!m_Archive->WriteString("/W[0 4 1]/Index["))
    702       return -1;
    703     if (IsIncremental() && m_pParser && m_pParser->GetLastXRefOffset() == 0) {
    704       uint32_t i = 0;
    705       for (i = 0; i < m_dwLastObjNum; i++) {
    706         if (!pdfium::ContainsKey(m_ObjectOffsets, i))
    707           continue;
    708         if (!m_Archive->WriteDWord(i) || !m_Archive->WriteString(" 1 "))
    709           return -1;
    710       }
    711       if (!m_Archive->WriteString("]/Length ") ||
    712           !m_Archive->WriteDWord(m_dwLastObjNum * 5) ||
    713           !m_Archive->WriteString(">>stream\r\n")) {
    714         return -1;
    715       }
    716       for (i = 0; i < m_dwLastObjNum; i++) {
    717         auto it = m_ObjectOffsets.find(i);
    718         if (it == m_ObjectOffsets.end())
    719           continue;
    720         OutputIndex(m_Archive.get(), it->second);
    721       }
    722     } else {
    723       size_t count = m_NewObjNumArray.size();
    724       size_t i = 0;
    725       for (i = 0; i < count; i++) {
    726         if (!m_Archive->WriteDWord(m_NewObjNumArray[i]) ||
    727             !m_Archive->WriteString(" 1 ")) {
    728           return -1;
    729         }
    730       }
    731       if (!m_Archive->WriteString("]/Length ") ||
    732           !m_Archive->WriteDWord(count * 5) ||
    733           !m_Archive->WriteString(">>stream\r\n")) {
    734         return -1;
    735       }
    736       for (i = 0; i < count; ++i)
    737         OutputIndex(m_Archive.get(), m_ObjectOffsets[m_NewObjNumArray[i]]);
    738     }
    739     if (!m_Archive->WriteString("\r\nendstream"))
    740       return -1;
    741   }
    742 
    743   if (!m_Archive->WriteString("\r\nstartxref\r\n"))
    744     return -1;
    745 
    746   char offset_buf[20];
    747   memset(offset_buf, 0, sizeof(offset_buf));
    748   FXSYS_i64toa(m_XrefStart, offset_buf, 10);
    749   if (!m_Archive->WriteBlock(offset_buf, strlen(offset_buf)) ||
    750       !m_Archive->WriteString("\r\n%%EOF\r\n")) {
    751     return -1;
    752   }
    753 
    754   m_iStage = 100;
    755   return m_iStage;
    756 }
    757 
    758 bool CPDF_Creator::Create(uint32_t flags) {
    759   m_dwFlags = flags;
    760   m_iStage = 0;
    761   m_dwLastObjNum = m_pDocument->GetLastObjNum();
    762   m_ObjectOffsets.clear();
    763   m_NewObjNumArray.clear();
    764 
    765   InitID();
    766   return Continue() > -1;
    767 }
    768 
    769 void CPDF_Creator::InitID() {
    770   const CPDF_Array* pOldIDArray = m_pParser ? m_pParser->GetIDArray() : nullptr;
    771 
    772   bool idArrayPreExisting = !!m_pIDArray;
    773   if (!idArrayPreExisting) {
    774     m_pIDArray = pdfium::MakeUnique<CPDF_Array>();
    775     CPDF_Object* pID1 = pOldIDArray ? pOldIDArray->GetObjectAt(0) : nullptr;
    776     if (pID1) {
    777       m_pIDArray->Add(pID1->Clone());
    778     } else {
    779       std::vector<uint8_t> buffer =
    780           GenerateFileID((uint32_t)(uintptr_t)this, m_dwLastObjNum);
    781       ByteString bsBuffer(buffer.data(), buffer.size());
    782       m_pIDArray->AddNew<CPDF_String>(bsBuffer, true);
    783     }
    784   }
    785 
    786   if (pOldIDArray) {
    787     CPDF_Object* pID2 = pOldIDArray->GetObjectAt(1);
    788     if (IsIncremental() && m_pEncryptDict && pID2) {
    789       m_pIDArray->Add(pID2->Clone());
    790       return;
    791     }
    792     std::vector<uint8_t> buffer =
    793         GenerateFileID((uint32_t)(uintptr_t)this, m_dwLastObjNum);
    794     ByteString bsBuffer(buffer.data(), buffer.size());
    795     m_pIDArray->AddNew<CPDF_String>(bsBuffer, true);
    796     return;
    797   }
    798 
    799   m_pIDArray->Add(m_pIDArray->GetObjectAt(0)->Clone());
    800   if (m_pEncryptDict && !pOldIDArray && m_pParser && !idArrayPreExisting) {
    801     if (m_pEncryptDict->GetStringFor("Filter") == "Standard") {
    802       ByteString user_pass = m_pParser->GetPassword();
    803       m_pSecurityHandler = pdfium::MakeUnique<CPDF_SecurityHandler>();
    804       m_pSecurityHandler->OnCreate(m_pEncryptDict.Get(), m_pIDArray.get(),
    805                                    user_pass);
    806       m_bSecurityChanged = true;
    807     }
    808   }
    809 }
    810 
    811 int32_t CPDF_Creator::Continue() {
    812   if (m_iStage < 0)
    813     return m_iStage;
    814 
    815   int32_t iRet = 0;
    816   while (m_iStage < 100) {
    817     if (m_iStage < 20)
    818       iRet = WriteDoc_Stage1();
    819     else if (m_iStage < 30)
    820       iRet = WriteDoc_Stage2();
    821     else if (m_iStage < 90)
    822       iRet = WriteDoc_Stage3();
    823     else
    824       iRet = WriteDoc_Stage4();
    825 
    826     if (iRet < m_iStage)
    827       break;
    828   }
    829 
    830   if (iRet < 1 || m_iStage == 100) {
    831     m_iStage = -1;
    832     return iRet > 99 ? 0 : (iRet < 1 ? -1 : iRet);
    833   }
    834   return m_iStage;
    835 }
    836 
    837 bool CPDF_Creator::SetFileVersion(int32_t fileVersion) {
    838   if (fileVersion < 10 || fileVersion > 17)
    839     return false;
    840   m_FileVersion = fileVersion;
    841   return true;
    842 }
    843 
    844 void CPDF_Creator::RemoveSecurity() {
    845   m_pSecurityHandler.Reset();
    846   m_bSecurityChanged = true;
    847   m_pEncryptDict = nullptr;
    848 }
    849 
    850 CPDF_CryptoHandler* CPDF_Creator::GetCryptoHandler() {
    851   return m_pSecurityHandler ? m_pSecurityHandler->GetCryptoHandler() : nullptr;
    852 }
    853