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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/parser/fpdf_parser_decode.h"
      8 
      9 #include <limits.h>
     10 
     11 #include <algorithm>
     12 #include <sstream>
     13 #include <utility>
     14 #include <vector>
     15 
     16 #include "core/fpdfapi/cpdf_modulemgr.h"
     17 #include "core/fpdfapi/parser/cpdf_array.h"
     18 #include "core/fpdfapi/parser/cpdf_dictionary.h"
     19 #include "core/fpdfapi/parser/fpdf_parser_utility.h"
     20 #include "core/fxcodec/codec/ccodec_faxmodule.h"
     21 #include "core/fxcodec/codec/ccodec_flatemodule.h"
     22 #include "core/fxcodec/codec/ccodec_scanlinedecoder.h"
     23 #include "core/fxcodec/fx_codec.h"
     24 #include "core/fxcrt/fx_extension.h"
     25 #include "third_party/base/numerics/safe_math.h"
     26 
     27 namespace {
     28 
     29 const uint32_t kMaxStreamSize = 20 * 1024 * 1024;
     30 
     31 uint16_t GetUnicodeFromBytes(const uint8_t* bytes, bool bBE) {
     32   return bBE ? (bytes[0] << 8 | bytes[1]) : (bytes[1] << 8 | bytes[0]);
     33 }
     34 
     35 bool CheckFlateDecodeParams(int Colors, int BitsPerComponent, int Columns) {
     36   if (Colors < 0 || BitsPerComponent < 0 || Columns < 0)
     37     return false;
     38 
     39   pdfium::base::CheckedNumeric<int> check = Columns;
     40   check *= Colors;
     41   check *= BitsPerComponent;
     42   if (!check.IsValid())
     43     return false;
     44 
     45   return check.ValueOrDie() <= INT_MAX - 7;
     46 }
     47 
     48 }  // namespace
     49 
     50 const uint16_t PDFDocEncoding[256] = {
     51     0x0000, 0x0001, 0x0002, 0x0003, 0x0004, 0x0005, 0x0006, 0x0007, 0x0008,
     52     0x0009, 0x000a, 0x000b, 0x000c, 0x000d, 0x000e, 0x000f, 0x0010, 0x0011,
     53     0x0012, 0x0013, 0x0014, 0x0015, 0x0016, 0x0017, 0x02d8, 0x02c7, 0x02c6,
     54     0x02d9, 0x02dd, 0x02db, 0x02da, 0x02dc, 0x0020, 0x0021, 0x0022, 0x0023,
     55     0x0024, 0x0025, 0x0026, 0x0027, 0x0028, 0x0029, 0x002a, 0x002b, 0x002c,
     56     0x002d, 0x002e, 0x002f, 0x0030, 0x0031, 0x0032, 0x0033, 0x0034, 0x0035,
     57     0x0036, 0x0037, 0x0038, 0x0039, 0x003a, 0x003b, 0x003c, 0x003d, 0x003e,
     58     0x003f, 0x0040, 0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047,
     59     0x0048, 0x0049, 0x004a, 0x004b, 0x004c, 0x004d, 0x004e, 0x004f, 0x0050,
     60     0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057, 0x0058, 0x0059,
     61     0x005a, 0x005b, 0x005c, 0x005d, 0x005e, 0x005f, 0x0060, 0x0061, 0x0062,
     62     0x0063, 0x0064, 0x0065, 0x0066, 0x0067, 0x0068, 0x0069, 0x006a, 0x006b,
     63     0x006c, 0x006d, 0x006e, 0x006f, 0x0070, 0x0071, 0x0072, 0x0073, 0x0074,
     64     0x0075, 0x0076, 0x0077, 0x0078, 0x0079, 0x007a, 0x007b, 0x007c, 0x007d,
     65     0x007e, 0x0000, 0x2022, 0x2020, 0x2021, 0x2026, 0x2014, 0x2013, 0x0192,
     66     0x2044, 0x2039, 0x203a, 0x2212, 0x2030, 0x201e, 0x201c, 0x201d, 0x2018,
     67     0x2019, 0x201a, 0x2122, 0xfb01, 0xfb02, 0x0141, 0x0152, 0x0160, 0x0178,
     68     0x017d, 0x0131, 0x0142, 0x0153, 0x0161, 0x017e, 0x0000, 0x20ac, 0x00a1,
     69     0x00a2, 0x00a3, 0x00a4, 0x00a5, 0x00a6, 0x00a7, 0x00a8, 0x00a9, 0x00aa,
     70     0x00ab, 0x00ac, 0x0000, 0x00ae, 0x00af, 0x00b0, 0x00b1, 0x00b2, 0x00b3,
     71     0x00b4, 0x00b5, 0x00b6, 0x00b7, 0x00b8, 0x00b9, 0x00ba, 0x00bb, 0x00bc,
     72     0x00bd, 0x00be, 0x00bf, 0x00c0, 0x00c1, 0x00c2, 0x00c3, 0x00c4, 0x00c5,
     73     0x00c6, 0x00c7, 0x00c8, 0x00c9, 0x00ca, 0x00cb, 0x00cc, 0x00cd, 0x00ce,
     74     0x00cf, 0x00d0, 0x00d1, 0x00d2, 0x00d3, 0x00d4, 0x00d5, 0x00d6, 0x00d7,
     75     0x00d8, 0x00d9, 0x00da, 0x00db, 0x00dc, 0x00dd, 0x00de, 0x00df, 0x00e0,
     76     0x00e1, 0x00e2, 0x00e3, 0x00e4, 0x00e5, 0x00e6, 0x00e7, 0x00e8, 0x00e9,
     77     0x00ea, 0x00eb, 0x00ec, 0x00ed, 0x00ee, 0x00ef, 0x00f0, 0x00f1, 0x00f2,
     78     0x00f3, 0x00f4, 0x00f5, 0x00f6, 0x00f7, 0x00f8, 0x00f9, 0x00fa, 0x00fb,
     79     0x00fc, 0x00fd, 0x00fe, 0x00ff};
     80 
     81 uint32_t A85Decode(const uint8_t* src_buf,
     82                    uint32_t src_size,
     83                    uint8_t** dest_buf,
     84                    uint32_t* dest_size) {
     85   *dest_size = 0;
     86   *dest_buf = nullptr;
     87   if (src_size == 0)
     88     return 0;
     89 
     90   // Count legal characters and zeros.
     91   uint32_t zcount = 0;
     92   uint32_t pos = 0;
     93   while (pos < src_size) {
     94     uint8_t ch = src_buf[pos];
     95     if (ch == 'z') {
     96       zcount++;
     97     } else if ((ch < '!' || ch > 'u') && !PDFCharIsLineEnding(ch) &&
     98                ch != ' ' && ch != '\t') {
     99       break;
    100     }
    101     pos++;
    102   }
    103   // No content to decode.
    104   if (pos == 0)
    105     return 0;
    106 
    107   // Count the space needed to contain non-zero characters. The encoding ratio
    108   // of Ascii85 is 4:5.
    109   uint32_t space_for_non_zeroes = (pos - zcount) / 5 * 4 + 4;
    110   if (zcount > (UINT_MAX - space_for_non_zeroes) / 4)
    111     return FX_INVALID_OFFSET;
    112 
    113   *dest_buf = FX_Alloc(uint8_t, zcount * 4 + space_for_non_zeroes);
    114   size_t state = 0;
    115   uint32_t res = 0;
    116   pos = 0;
    117   while (pos < src_size) {
    118     uint8_t ch = src_buf[pos++];
    119     if (PDFCharIsLineEnding(ch) || ch == ' ' || ch == '\t')
    120       continue;
    121 
    122     if (ch == 'z') {
    123       memset(*dest_buf + *dest_size, 0, 4);
    124       state = 0;
    125       res = 0;
    126       *dest_size += 4;
    127       continue;
    128     }
    129 
    130     // Check for the end or illegal character.
    131     if (ch < '!' || ch > 'u')
    132       break;
    133 
    134     res = res * 85 + ch - 33;
    135     if (state < 4) {
    136       ++state;
    137       continue;
    138     }
    139 
    140     for (size_t i = 0; i < 4; ++i) {
    141       (*dest_buf)[(*dest_size)++] = static_cast<uint8_t>(res >> (3 - i) * 8);
    142     }
    143     state = 0;
    144     res = 0;
    145   }
    146   // Handle partial group.
    147   if (state) {
    148     for (size_t i = state; i < 5; ++i)
    149       res = res * 85 + 84;
    150     for (size_t i = 0; i < state - 1; ++i)
    151       (*dest_buf)[(*dest_size)++] = static_cast<uint8_t>(res >> (3 - i) * 8);
    152   }
    153   if (pos < src_size && src_buf[pos] == '>')
    154     ++pos;
    155   return pos;
    156 }
    157 
    158 uint32_t HexDecode(const uint8_t* src_buf,
    159                    uint32_t src_size,
    160                    uint8_t** dest_buf,
    161                    uint32_t* dest_size) {
    162   *dest_size = 0;
    163   if (src_size == 0) {
    164     *dest_buf = nullptr;
    165     return 0;
    166   }
    167 
    168   uint32_t i = 0;
    169   // Find the end of data.
    170   while (i < src_size && src_buf[i] != '>')
    171     ++i;
    172 
    173   *dest_buf = FX_Alloc(uint8_t, i / 2 + 1);
    174   bool bFirst = true;
    175   for (i = 0; i < src_size; ++i) {
    176     uint8_t ch = src_buf[i];
    177     if (PDFCharIsLineEnding(ch) || ch == ' ' || ch == '\t')
    178       continue;
    179 
    180     if (ch == '>') {
    181       ++i;
    182       break;
    183     }
    184     if (!std::isxdigit(ch))
    185       continue;
    186 
    187     int digit = FXSYS_HexCharToInt(ch);
    188     if (bFirst)
    189       (*dest_buf)[*dest_size] = digit * 16;
    190     else
    191       (*dest_buf)[(*dest_size)++] += digit;
    192     bFirst = !bFirst;
    193   }
    194   if (!bFirst)
    195     ++(*dest_size);
    196   return i;
    197 }
    198 
    199 uint32_t RunLengthDecode(const uint8_t* src_buf,
    200                          uint32_t src_size,
    201                          uint8_t** dest_buf,
    202                          uint32_t* dest_size) {
    203   uint32_t i = 0;
    204   *dest_size = 0;
    205   while (i < src_size) {
    206     if (src_buf[i] == 128)
    207       break;
    208 
    209     uint32_t old = *dest_size;
    210     if (src_buf[i] < 128) {
    211       *dest_size += src_buf[i] + 1;
    212       if (*dest_size < old)
    213         return FX_INVALID_OFFSET;
    214       i += src_buf[i] + 2;
    215     } else {
    216       *dest_size += 257 - src_buf[i];
    217       if (*dest_size < old)
    218         return FX_INVALID_OFFSET;
    219       i += 2;
    220     }
    221   }
    222   if (*dest_size >= kMaxStreamSize)
    223     return FX_INVALID_OFFSET;
    224 
    225   *dest_buf = FX_Alloc(uint8_t, *dest_size);
    226   i = 0;
    227   int dest_count = 0;
    228   while (i < src_size) {
    229     if (src_buf[i] == 128)
    230       break;
    231 
    232     if (src_buf[i] < 128) {
    233       uint32_t copy_len = src_buf[i] + 1;
    234       uint32_t buf_left = src_size - i - 1;
    235       if (buf_left < copy_len) {
    236         uint32_t delta = copy_len - buf_left;
    237         copy_len = buf_left;
    238         memset(*dest_buf + dest_count + copy_len, '\0', delta);
    239       }
    240       memcpy(*dest_buf + dest_count, src_buf + i + 1, copy_len);
    241       dest_count += src_buf[i] + 1;
    242       i += src_buf[i] + 2;
    243     } else {
    244       int fill = 0;
    245       if (i < src_size - 1)
    246         fill = src_buf[i + 1];
    247       memset(*dest_buf + dest_count, fill, 257 - src_buf[i]);
    248       dest_count += 257 - src_buf[i];
    249       i += 2;
    250     }
    251   }
    252   return std::min(i + 1, src_size);
    253 }
    254 
    255 std::unique_ptr<CCodec_ScanlineDecoder> FPDFAPI_CreateFaxDecoder(
    256     const uint8_t* src_buf,
    257     uint32_t src_size,
    258     int width,
    259     int height,
    260     const CPDF_Dictionary* pParams) {
    261   int K = 0;
    262   bool EndOfLine = false;
    263   bool ByteAlign = false;
    264   bool BlackIs1 = false;
    265   int Columns = 1728;
    266   int Rows = 0;
    267   if (pParams) {
    268     K = pParams->GetIntegerFor("K");
    269     EndOfLine = !!pParams->GetIntegerFor("EndOfLine");
    270     ByteAlign = !!pParams->GetIntegerFor("EncodedByteAlign");
    271     BlackIs1 = !!pParams->GetIntegerFor("BlackIs1");
    272     Columns = pParams->GetIntegerFor("Columns", 1728);
    273     Rows = pParams->GetIntegerFor("Rows");
    274     if (Rows > USHRT_MAX)
    275       Rows = 0;
    276   }
    277   return CPDF_ModuleMgr::Get()->GetFaxModule()->CreateDecoder(
    278       src_buf, src_size, width, height, K, EndOfLine, ByteAlign, BlackIs1,
    279       Columns, Rows);
    280 }
    281 
    282 std::unique_ptr<CCodec_ScanlineDecoder> FPDFAPI_CreateFlateDecoder(
    283     const uint8_t* src_buf,
    284     uint32_t src_size,
    285     int width,
    286     int height,
    287     int nComps,
    288     int bpc,
    289     const CPDF_Dictionary* pParams) {
    290   int predictor = 0;
    291   int Colors = 0;
    292   int BitsPerComponent = 0;
    293   int Columns = 0;
    294   if (pParams) {
    295     predictor = pParams->GetIntegerFor("Predictor");
    296     Colors = pParams->GetIntegerFor("Colors", 1);
    297     BitsPerComponent = pParams->GetIntegerFor("BitsPerComponent", 8);
    298     Columns = pParams->GetIntegerFor("Columns", 1);
    299     if (!CheckFlateDecodeParams(Colors, BitsPerComponent, Columns))
    300       return nullptr;
    301   }
    302   return CPDF_ModuleMgr::Get()->GetFlateModule()->CreateDecoder(
    303       src_buf, src_size, width, height, nComps, bpc, predictor, Colors,
    304       BitsPerComponent, Columns);
    305 }
    306 
    307 uint32_t FPDFAPI_FlateOrLZWDecode(bool bLZW,
    308                                   const uint8_t* src_buf,
    309                                   uint32_t src_size,
    310                                   CPDF_Dictionary* pParams,
    311                                   uint32_t estimated_size,
    312                                   uint8_t** dest_buf,
    313                                   uint32_t* dest_size) {
    314   int predictor = 0;
    315   int Colors = 0;
    316   int BitsPerComponent = 0;
    317   int Columns = 0;
    318   bool bEarlyChange = true;
    319   if (pParams) {
    320     predictor = pParams->GetIntegerFor("Predictor");
    321     bEarlyChange = !!pParams->GetIntegerFor("EarlyChange", 1);
    322     Colors = pParams->GetIntegerFor("Colors", 1);
    323     BitsPerComponent = pParams->GetIntegerFor("BitsPerComponent", 8);
    324     Columns = pParams->GetIntegerFor("Columns", 1);
    325     if (!CheckFlateDecodeParams(Colors, BitsPerComponent, Columns))
    326       return FX_INVALID_OFFSET;
    327   }
    328   return CPDF_ModuleMgr::Get()->GetFlateModule()->FlateOrLZWDecode(
    329       bLZW, src_buf, src_size, bEarlyChange, predictor, Colors,
    330       BitsPerComponent, Columns, estimated_size, dest_buf, dest_size);
    331 }
    332 
    333 bool PDF_DataDecode(const uint8_t* src_buf,
    334                     uint32_t src_size,
    335                     const CPDF_Dictionary* pDict,
    336                     uint32_t last_estimated_size,
    337                     bool bImageAcc,
    338                     uint8_t** dest_buf,
    339                     uint32_t* dest_size,
    340                     ByteString* ImageEncoding,
    341                     CPDF_Dictionary** pImageParms) {
    342   CPDF_Object* pDecoder = pDict ? pDict->GetDirectObjectFor("Filter") : nullptr;
    343   if (!pDecoder || (!pDecoder->IsArray() && !pDecoder->IsName()))
    344     return false;
    345 
    346   CPDF_Object* pParams =
    347       pDict ? pDict->GetDirectObjectFor("DecodeParms") : nullptr;
    348 
    349   std::vector<std::pair<ByteString, CPDF_Object*>> DecoderArray;
    350   if (CPDF_Array* pDecoders = pDecoder->AsArray()) {
    351     CPDF_Array* pParamsArray = ToArray(pParams);
    352     for (size_t i = 0; i < pDecoders->GetCount(); ++i) {
    353       DecoderArray.push_back(
    354           {pDecoders->GetStringAt(i),
    355            pParamsArray ? pParamsArray->GetDictAt(i) : nullptr});
    356     }
    357   } else {
    358     DecoderArray.push_back(
    359         {pDecoder->GetString(), pParams ? pParams->GetDict() : nullptr});
    360   }
    361   uint8_t* last_buf = const_cast<uint8_t*>(src_buf);
    362   uint32_t last_size = src_size;
    363   size_t nSize = DecoderArray.size();
    364   for (size_t i = 0; i < nSize; ++i) {
    365     int estimated_size = i == nSize - 1 ? last_estimated_size : 0;
    366     ByteString decoder = DecoderArray[i].first;
    367     CPDF_Dictionary* pParam = ToDictionary(DecoderArray[i].second);
    368     uint8_t* new_buf = nullptr;
    369     uint32_t new_size = 0xFFFFFFFF;
    370     uint32_t offset = FX_INVALID_OFFSET;
    371     if (decoder == "Crypt")
    372       continue;
    373     if (decoder == "FlateDecode" || decoder == "Fl") {
    374       if (bImageAcc && i == nSize - 1) {
    375         *ImageEncoding = "FlateDecode";
    376         *dest_buf = last_buf;
    377         *dest_size = last_size;
    378         *pImageParms = pParam;
    379         return true;
    380       }
    381       offset = FPDFAPI_FlateOrLZWDecode(false, last_buf, last_size, pParam,
    382                                         estimated_size, &new_buf, &new_size);
    383     } else if (decoder == "LZWDecode" || decoder == "LZW") {
    384       offset = FPDFAPI_FlateOrLZWDecode(true, last_buf, last_size, pParam,
    385                                         estimated_size, &new_buf, &new_size);
    386     } else if (decoder == "ASCII85Decode" || decoder == "A85") {
    387       offset = A85Decode(last_buf, last_size, &new_buf, &new_size);
    388     } else if (decoder == "ASCIIHexDecode" || decoder == "AHx") {
    389       offset = HexDecode(last_buf, last_size, &new_buf, &new_size);
    390     } else if (decoder == "RunLengthDecode" || decoder == "RL") {
    391       if (bImageAcc && i == nSize - 1) {
    392         *ImageEncoding = "RunLengthDecode";
    393         *dest_buf = last_buf;
    394         *dest_size = last_size;
    395         *pImageParms = pParam;
    396         return true;
    397       }
    398       offset = RunLengthDecode(last_buf, last_size, &new_buf, &new_size);
    399     } else {
    400       // If we get here, assume it's an image decoder.
    401       if (decoder == "DCT")
    402         decoder = "DCTDecode";
    403       else if (decoder == "CCF")
    404         decoder = "CCITTFaxDecode";
    405       *ImageEncoding = decoder;
    406       *pImageParms = pParam;
    407       *dest_buf = last_buf;
    408       *dest_size = last_size;
    409       return true;
    410     }
    411     if (last_buf != src_buf)
    412       FX_Free(last_buf);
    413     if (offset == FX_INVALID_OFFSET) {
    414       FX_Free(new_buf);
    415       return false;
    416     }
    417     last_buf = new_buf;
    418     last_size = new_size;
    419   }
    420   ImageEncoding->clear();
    421   *pImageParms = nullptr;
    422   *dest_buf = last_buf;
    423   *dest_size = last_size;
    424   return true;
    425 }
    426 
    427 WideString PDF_DecodeText(const uint8_t* src_data, uint32_t src_len) {
    428   WideString result;
    429   if (src_len >= 2 && ((src_data[0] == 0xfe && src_data[1] == 0xff) ||
    430                        (src_data[0] == 0xff && src_data[1] == 0xfe))) {
    431     uint32_t max_chars = (src_len - 2) / 2;
    432     if (!max_chars)
    433       return result;
    434 
    435     bool bBE = src_data[0] == 0xfe || (src_data[0] == 0xff && !src_data[2]);
    436     wchar_t* dest_buf = result.GetBuffer(max_chars);
    437     const uint8_t* uni_str = src_data + 2;
    438     int dest_pos = 0;
    439     for (uint32_t i = 0; i < max_chars * 2; i += 2) {
    440       uint16_t unicode = GetUnicodeFromBytes(uni_str + i, bBE);
    441       if (unicode != 0x1b) {
    442         dest_buf[dest_pos++] = unicode;
    443         continue;
    444       }
    445 
    446       i += 2;
    447       while (i < max_chars * 2) {
    448         uint16_t unicode2 = GetUnicodeFromBytes(uni_str + i, bBE);
    449         i += 2;
    450         if (unicode2 == 0x1b)
    451           break;
    452       }
    453     }
    454     result.ReleaseBuffer(dest_pos);
    455   } else {
    456     wchar_t* dest_buf = result.GetBuffer(src_len);
    457     for (uint32_t i = 0; i < src_len; ++i)
    458       dest_buf[i] = PDFDocEncoding[src_data[i]];
    459     result.ReleaseBuffer(src_len);
    460   }
    461   return result;
    462 }
    463 
    464 WideString PDF_DecodeText(const ByteString& bstr) {
    465   return PDF_DecodeText(reinterpret_cast<const uint8_t*>(bstr.c_str()),
    466                         bstr.GetLength());
    467 }
    468 
    469 ByteString PDF_EncodeText(const wchar_t* pString, int len) {
    470   if (len == -1)
    471     len = wcslen(pString);
    472 
    473   ByteString result;
    474   char* dest_buf1 = result.GetBuffer(len);
    475   int i;
    476   for (i = 0; i < len; ++i) {
    477     int code;
    478     for (code = 0; code < 256; ++code) {
    479       if (PDFDocEncoding[code] == pString[i])
    480         break;
    481     }
    482 
    483     if (code == 256)
    484       break;
    485 
    486     dest_buf1[i] = code;
    487   }
    488   result.ReleaseBuffer(i);
    489   if (i == len)
    490     return result;
    491 
    492   if (len > INT_MAX / 2 - 1) {
    493     result.ReleaseBuffer(0);
    494     return result;
    495   }
    496 
    497   int encLen = len * 2 + 2;
    498 
    499   uint8_t* dest_buf2 = reinterpret_cast<uint8_t*>(result.GetBuffer(encLen));
    500   dest_buf2[0] = 0xfe;
    501   dest_buf2[1] = 0xff;
    502   dest_buf2 += 2;
    503   for (int j = 0; j < len; ++j) {
    504     *dest_buf2++ = pString[j] >> 8;
    505     *dest_buf2++ = static_cast<uint8_t>(pString[j]);
    506   }
    507   result.ReleaseBuffer(encLen);
    508   return result;
    509 }
    510 
    511 ByteString PDF_EncodeText(const WideString& str) {
    512   return PDF_EncodeText(str.c_str(), str.GetLength());
    513 }
    514 
    515 ByteString PDF_EncodeString(const ByteString& src, bool bHex) {
    516   std::ostringstream result;
    517   int srclen = src.GetLength();
    518   if (bHex) {
    519     result << '<';
    520     for (int i = 0; i < srclen; ++i) {
    521       char buf[2];
    522       FXSYS_IntToTwoHexChars(src[i], buf);
    523       result << buf[0];
    524       result << buf[1];
    525     }
    526     result << '>';
    527     return ByteString(result);
    528   }
    529   result << '(';
    530   for (int i = 0; i < srclen; ++i) {
    531     uint8_t ch = src[i];
    532     if (ch == 0x0a) {
    533       result << "\\n";
    534       continue;
    535     }
    536     if (ch == 0x0d) {
    537       result << "\\r";
    538       continue;
    539     }
    540     if (ch == ')' || ch == '\\' || ch == '(')
    541       result << '\\';
    542     result << static_cast<char>(ch);
    543   }
    544   result << ')';
    545   return ByteString(result);
    546 }
    547 
    548 bool FlateEncode(const uint8_t* src_buf,
    549                  uint32_t src_size,
    550                  uint8_t** dest_buf,
    551                  uint32_t* dest_size) {
    552   CCodec_ModuleMgr* pEncoders = CPDF_ModuleMgr::Get()->GetCodecModule();
    553   return pEncoders->GetFlateModule()->Encode(src_buf, src_size, dest_buf,
    554                                              dest_size);
    555 }
    556 
    557 bool PngEncode(const uint8_t* src_buf,
    558                uint32_t src_size,
    559                uint8_t** dest_buf,
    560                uint32_t* dest_size) {
    561   CCodec_ModuleMgr* pEncoders = CPDF_ModuleMgr::Get()->GetCodecModule();
    562   return pEncoders->GetFlateModule()->PngEncode(src_buf, src_size, dest_buf,
    563                                                 dest_size);
    564 }
    565 
    566 uint32_t FlateDecode(const uint8_t* src_buf,
    567                      uint32_t src_size,
    568                      uint8_t** dest_buf,
    569                      uint32_t* dest_size) {
    570   CCodec_ModuleMgr* pEncoders = CPDF_ModuleMgr::Get()->GetCodecModule();
    571   return pEncoders->GetFlateModule()->FlateOrLZWDecode(
    572       false, src_buf, src_size, false, 0, 0, 0, 0, 0, dest_buf, dest_size);
    573 }
    574