text: /**
   * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
   * All rights reserved.
   *
   * This source code is licensed under the BSD-style license found in the
   * LICENSE file in the root directory of this source tree. An additional grant
   * of patent rights can be found in the PATENTS file in the same directory.
   */
  
  
  /*
    Note : this file is part of zstd command line, which is not library.
    The license of ZSTD library is BSD.
    The license of this file is GPLv2.
  */
  
  
  /* *************************************
   *  Tuning options
   ***************************************/
  #ifndef ZSTD_LEGACY_SUPPORT
  /* LEGACY_SUPPORT :
   *  decompressor can decode older formats (starting from Zstd 0.1+) */
  #  define ZSTD_LEGACY_SUPPORT 1
  #endif
  
  
  /* *************************************
  *  Compiler Options
  ***************************************/
  #ifdef _MSC_VER   /* Visual */
  #  define _CRT_SECURE_NO_WARNINGS  /* removes Visual warning on strerror() */
  #  pragma warning(disable : 4204)  /* non-constant aggregate initializer */
  #endif
  #if defined(__MINGW32__) && !defined(_POSIX_SOURCE)
  #  define _POSIX_SOURCE 1          /* disable %llu warnings with MinGW on Windows */
  #endif
  
  /*-*************************************
  *  Includes
  ***************************************/
  #include "util.h"       /* Compiler options, UTIL_GetFileSize, _LARGEFILE64_SOURCE */
  #include <stdio.h>      /* fprintf, fopen, fread, _fileno, stdin, stdout */
  #include <stdlib.h>     /* malloc, free */
  #include <string.h>     /* strcmp, strlen */
  #include <time.h>       /* clock */
  #include <errno.h>      /* errno */
  
  #include "mem.h"
  #include "fileio.h"
  #define ZSTD_STATIC_LINKING_ONLY   /* ZSTD_magicNumber, ZSTD_frameHeaderSize_max */
  #include "zstd.h"
  
  #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT==1)
  #  include "zstd_legacy.h"    /* ZSTD_isLegacy */
  #endif
  
  
  /*-*************************************
  *  OS-specific Includes
  ***************************************/
  #if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
  #  include <fcntl.h>    /* _O_BINARY */
  #  include <io.h>       /* _setmode, _isatty */
  #  define SET_BINARY_MODE(file) { if (_setmode(_fileno(file), _O_BINARY) == -1) perror("Cannot set _O_BINARY"); }
  #else
  #  include <unistd.h>   /* isatty */
  #  define SET_BINARY_MODE(file)
  #endif
  
  
  /*-*************************************
  *  Constants
  ***************************************/
  #define KB *(1<<10)
  #define MB *(1<<20)
  #define GB *(1U<<30)
  
  #define _1BIT  0x01
  #define _2BITS 0x03
  #define _3BITS 0x07
  #define _4BITS 0x0F
  #define _6BITS 0x3F
  #define _8BITS 0xFF
  
  #define BLOCKSIZE      (128 KB)
  #define ROLLBUFFERSIZE (BLOCKSIZE*8*64)
  
  #define FIO_FRAMEHEADERSIZE  5        /* as a define, because needed to allocated table on stack */
  #define FSE_CHECKSUM_SEED    0
  
  #define CACHELINE 64
  
  #define MAX_DICT_SIZE (8 MB)   /* protection against large input (attack scenario) */
  
  #define FNSPACE 30
  
  
  /*-*************************************
  *  Macros
  ***************************************/
  #define DISPLAY(...)         fprintf(stderr, __VA_ARGS__)
  #define DISPLAYLEVEL(l, ...) if (g_displayLevel>=l) { DISPLAY(__VA_ARGS__); }
  static U32 g_displayLevel = 2;   /* 0 : no display;   1: errors;   2 : + result + interaction + warnings;   3 : + progression;   4 : + information */
  void FIO_setNotificationLevel(unsigned level) { g_displayLevel=level; }
  
  #define DISPLAYUPDATE(l, ...) if (g_displayLevel>=l) { \
              if ((clock() - g_time > refreshRate) || (g_displayLevel>=4)) \
              { g_time = clock(); DISPLAY(__VA_ARGS__); \
              if (g_displayLevel>=4) fflush(stdout); } }
  static const clock_t refreshRate = CLOCKS_PER_SEC * 15 / 100;
  static clock_t g_time = 0;
  
  #define MIN(a,b)    ((a) < (b) ? (a) : (b))
  
  
  /*-*************************************
  *  Local Parameters - Not thread safe
  ***************************************/
  static U32 g_overwrite = 0;
  void FIO_overwriteMode(void) { g_overwrite=1; }
  static U32 g_maxWLog = 23;
  void FIO_setMaxWLog(unsigned maxWLog) { g_maxWLog = maxWLog; }
  static U32 g_sparseFileSupport = 1;   /* 0 : no sparse allowed; 1: auto (file yes, stdout no); 2: force sparse */
  void FIO_setSparseWrite(unsigned sparse) { g_sparseFileSupport=sparse; }
  static U32 g_dictIDFlag = 1;
  void FIO_setDictIDFlag(unsigned dictIDFlag) { g_dictIDFlag = dictIDFlag; }
  static U32 g_checksumFlag = 1;
  void FIO_setChecksumFlag(unsigned checksumFlag) { g_checksumFlag = checksumFlag; }
  static U32 g_removeSrcFile = 0;
  void FIO_setRemoveSrcFile(unsigned flag) { g_removeSrcFile = (flag>0); }
  
  
  /*-*************************************
  *  Exceptions
  ***************************************/
  #ifndef DEBUG
  #  define DEBUG 0
  #endif
  #define DEBUGOUTPUT(...) if (DEBUG) DISPLAY(__VA_ARGS__);
  #define EXM_THROW(error, ...)                                             \
  {                                                                         \
      DEBUGOUTPUT("Error defined at %s, line %i : \n", __FILE__, __LINE__); \
      DISPLAYLEVEL(1, "Error %i : ", error);                                \
      DISPLAYLEVEL(1, __VA_ARGS__);                                         \
      DISPLAYLEVEL(1, "\n");                                                \
      exit(error);                                                          \
  }
  
  
  /*-*************************************
  *  Functions
  ***************************************/
  static FILE* FIO_openSrcFile(const char* srcFileName)
  {
      FILE* f;
  
      if (!strcmp (srcFileName, stdinmark)) {
          DISPLAYLEVEL(4,"Using stdin for input\n");
          f = stdin;
          SET_BINARY_MODE(stdin);
      } else {
          f = fopen(srcFileName, "rb");
          if ( f==NULL ) DISPLAYLEVEL(1, "zstd: %s: %s \n", srcFileName, strerror(errno));
      }
  
      return f;
  }
  
  /* `dstFileName must` be non-NULL */
  static FILE* FIO_openDstFile(const char* dstFileName)
  {
      FILE* f;
  
      if (!strcmp (dstFileName, stdoutmark)) {
          DISPLAYLEVEL(4,"Using stdout for output\n");
          f = stdout;
          SET_BINARY_MODE(stdout);
          if (g_sparseFileSupport==1) {
              g_sparseFileSupport = 0;
              DISPLAYLEVEL(4, "Sparse File Support is automatically disabled on stdout ; try --sparse \n");
          }
      } else {
          if (!g_overwrite && strcmp (dstFileName, nulmark)) {  /* Check if destination file already exists */
              f = fopen( dstFileName, "rb" );
              if (f != 0) {  /* dest file exists, prompt for overwrite authorization */
                  fclose(f);
                  if (g_displayLevel <= 1) {
                      /* No interaction possible */
                      DISPLAY("zstd: %s already exists; not overwritten  \n", dstFileName);
                      return NULL;
                  }
                  DISPLAY("zstd: %s already exists; do you wish to overwrite (y/N) ? ", dstFileName);
                  {   int ch = getchar();
                      if ((ch!='Y') && (ch!='y')) {
                          DISPLAY("    not overwritten  \n");
                          return NULL;
                      }
                      while ((ch!=EOF) && (ch!='\n')) ch = getchar();  /* flush rest of input line */
          }   }   }
          f = fopen( dstFileName, "wb" );
          if (f==NULL) DISPLAYLEVEL(1, "zstd: %s: %s\n", dstFileName, strerror(errno));
      }
  
      return f;
  }
  
  
  /*! FIO_loadFile() :
  *   creates a buffer, pointed by `*bufferPtr`,
  *   loads `filename` content into it,
  *   up to MAX_DICT_SIZE bytes.
  *   @return : loaded size
  */
  static size_t FIO_loadFile(void** bufferPtr, const char* fileName)
  {
      FILE* fileHandle;
      U64 fileSize;
  
      *bufferPtr = NULL;
      if (fileName == NULL) return 0;
  
      DISPLAYLEVEL(4,"Loading %s as dictionary \n", fileName);
      fileHandle = fopen(fileName, "rb");
      if (fileHandle==0) EXM_THROW(31, "zstd: %s: %s", fileName, strerror(errno));
      fileSize = UTIL_getFileSize(fileName);
      if (fileSize > MAX_DICT_SIZE) {
          int seekResult;
          if (fileSize > 1 GB) EXM_THROW(32, "Dictionary file %s is too large", fileName);   /* avoid extreme cases */
          DISPLAYLEVEL(2,"Dictionary %s is too large : using last %u bytes only \n", fileName, (U32)MAX_DICT_SIZE);
          seekResult = fseek(fileHandle, (long int)(fileSize-MAX_DICT_SIZE), SEEK_SET);   /* use end of file */
          if (seekResult != 0) EXM_THROW(33, "zstd: %s: %s", fileName, strerror(errno));
          fileSize = MAX_DICT_SIZE;
      }
      *bufferPtr = malloc((size_t)fileSize);
      if (*bufferPtr==NULL) EXM_THROW(34, "zstd: %s", strerror(errno));
      { size_t const readSize = fread(*bufferPtr, 1, (size_t)fileSize, fileHandle);
        if (readSize!=fileSize) EXM_THROW(35, "Error reading dictionary file %s", fileName); }
      fclose(fileHandle);
      return (size_t)fileSize;
  }
  
  #ifndef ZSTD_NOCOMPRESS
  
  /*-**********************************************************************
  *  Compression
  ************************************************************************/
  typedef struct {
      void*  srcBuffer;
      size_t srcBufferSize;
      void*  dstBuffer;
      size_t dstBufferSize;
      void*  dictBuffer;
      size_t dictBufferSize;
      ZSTD_CStream* cctx;
      FILE* dstFile;
      FILE* srcFile;
  } cRess_t;
  
  static cRess_t FIO_createCResources(const char* dictFileName)
  {
      cRess_t ress;
      memset(&ress, 0, sizeof(ress));
  
      ress.cctx = ZSTD_createCStream();
      if (ress.cctx == NULL) EXM_THROW(30, "zstd: allocation error : can't create ZSTD_CStream");
      ress.srcBufferSize = ZSTD_CStreamInSize();
      ress.srcBuffer = malloc(ress.srcBufferSize);
      ress.dstBufferSize = ZSTD_CStreamOutSize();
      ress.dstBuffer = malloc(ress.dstBufferSize);
      if (!ress.srcBuffer || !ress.dstBuffer) EXM_THROW(31, "zstd: allocation error : not enough memory");
  
      /* dictionary */
      ress.dictBufferSize = FIO_loadFile(&(ress.dictBuffer), dictFileName);
  
      return ress;
  }
  
  static void FIO_freeCResources(cRess_t ress)
  {
      size_t errorCode;
      free(ress.srcBuffer);
      free(ress.dstBuffer);
      free(ress.dictBuffer);
      errorCode = ZSTD_freeCStream(ress.cctx);
      if (ZSTD_isError(errorCode)) EXM_THROW(38, "zstd: error : can't release ZSTD_CStream : %s", ZSTD_getErrorName(errorCode));
  }
  
  
  /*! FIO_compressFilename_internal() :
   *  same as FIO_compressFilename_extRess(), with `ress.desFile` already opened.
   *  @return : 0 : compression completed correctly,
   *            1 : missing or pb opening srcFileName
   */
  static int FIO_compressFilename_internal(cRess_t ress,
                                           const char* dstFileName, const char* srcFileName,
                                           int cLevel)
  {
      FILE* const srcFile = ress.srcFile;
      FILE* const dstFile = ress.dstFile;
      U64 readsize = 0;
      U64 compressedfilesize = 0;
      U64 const fileSize = UTIL_getFileSize(srcFileName);
  
      /* init */
      {   ZSTD_parameters params = ZSTD_getParams(cLevel, fileSize, ress.dictBufferSize);
          params.fParams.contentSizeFlag = 1;
          params.fParams.checksumFlag = g_checksumFlag;
          params.fParams.noDictIDFlag = !g_dictIDFlag;
          if ((g_maxWLog) && (params.cParams.windowLog > g_maxWLog)) {
              params.cParams.windowLog = g_maxWLog;
              params.cParams = ZSTD_adjustCParams(params.cParams, fileSize, ress.dictBufferSize);
          }
          {   size_t const errorCode = ZSTD_initCStream_advanced(ress.cctx, ress.dictBuffer, ress.dictBufferSize, params, fileSize);
              if (ZSTD_isError(errorCode)) EXM_THROW(21, "Error initializing compression : %s", ZSTD_getErrorName(errorCode));
      }   }
  
      /* Main compression loop */
      while (1) {
          /* Fill input Buffer */
          size_t const inSize = fread(ress.srcBuffer, (size_t)1, ress.srcBufferSize, srcFile);
          if (inSize==0) break;
          readsize += inSize;
          DISPLAYUPDATE(2, "\rRead : %u MB  ", (U32)(readsize>>20));
  
          /* Compress using buffered streaming */
          {   ZSTD_inBuffer  inBuff = { ress.srcBuffer, inSize, 0 };
              ZSTD_outBuffer outBuff= { ress.dstBuffer, ress.dstBufferSize, 0 };
              { size_t const result = ZSTD_compressStream(ress.cctx, &outBuff, &inBuff);
                if (ZSTD_isError(result)) EXM_THROW(23, "Compression error : %s ", ZSTD_getErrorName(result)); }
              if (inBuff.pos != inBuff.size)
                  /* inBuff should be entirely consumed since buffer sizes are recommended ones */
                  EXM_THROW(24, "Compression error : input block not fully consumed");
  
              /* Write cBlock */
              { size_t const sizeCheck = fwrite(ress.dstBuffer, 1, outBuff.pos, dstFile);
                if (sizeCheck!=outBuff.pos) EXM_THROW(25, "Write error : cannot write compressed block into %s", dstFileName); }
              compressedfilesize += outBuff.pos;
          }
          DISPLAYUPDATE(2, "\rRead : %u MB  ==> %.2f%%   ", (U32)(readsize>>20), (double)compressedfilesize/readsize*100);
      }
  
      /* End of Frame */
      {   ZSTD_outBuffer outBuff = { ress.dstBuffer, ress.dstBufferSize, 0 };
          size_t const result = ZSTD_endStream(ress.cctx, &outBuff);
          if (result!=0) EXM_THROW(26, "Compression error : cannot create frame end");
  
          { size_t const sizeCheck = fwrite(ress.dstBuffer, 1, outBuff.pos, dstFile);
            if (sizeCheck!=outBuff.pos) EXM_THROW(27, "Write error : cannot write frame end into %s", dstFileName); }
          compressedfilesize += outBuff.pos;
      }
  
      /* Status */
      DISPLAYLEVEL(2, "\r%79s\r", "");
      DISPLAYLEVEL(2,"%-20s :%6.2f%%   (%6llu => %6llu bytes, %s) \n", srcFileName,
          (double)compressedfilesize/(readsize+(!readsize) /* avoid div by zero */ )*100,
          (unsigned long long)readsize, (unsigned long long) compressedfilesize,
           dstFileName);
  
      return 0;
  }
  
  
  /*! FIO_compressFilename_srcFile() :
   *  note : ress.destFile already opened
   *  @return : 0 : compression completed correctly,
   *            1 : missing or pb opening srcFileName
   */
  static int FIO_compressFilename_srcFile(cRess_t ress,
                                          const char* dstFileName, const char* srcFileName,
                                          int cLevel)
  {
      int result;
  
      /* File check */
      if (UTIL_isDirectory(srcFileName)) {
          DISPLAYLEVEL(1, "zstd: %s is a directory -- ignored \n", srcFileName);
          return 1;
      }
      ress.srcFile = FIO_openSrcFile(srcFileName);
      if (!ress.srcFile) return 1;   /* srcFile could not be opened */
  
      result = FIO_compressFilename_internal(ress, dstFileName, srcFileName, cLevel);
  
      fclose(ress.srcFile);
      if ((g_removeSrcFile) && (!result)) { if (remove(srcFileName)) EXM_THROW(1, "zstd: %s: %s", srcFileName, strerror(errno)); }
      return result;
  }
  
  
  /*! FIO_compressFilename_dstFile() :
   *  @return : 0 : compression completed correctly,
   *            1 : pb
   */
  static int FIO_compressFilename_dstFile(cRess_t ress,
                                          const char* dstFileName, const char* srcFileName,
                                          int cLevel)
  {
      int result;
  
      ress.dstFile = FIO_openDstFile(dstFileName);
      if (ress.dstFile==0) return 1;
  
      result = FIO_compressFilename_srcFile(ress, dstFileName, srcFileName, cLevel);
  
      if (fclose(ress.dstFile)) { DISPLAYLEVEL(1, "zstd: %s: %s \n", dstFileName, strerror(errno)); result=1; }
      if (result!=0) { if (remove(dstFileName)) EXM_THROW(1, "zstd: %s: %s", dstFileName, strerror(errno)); }  /* remove operation artefact */
      return result;
  }
  
  
  int FIO_compressFilename(const char* dstFileName, const char* srcFileName,
                           const char* dictFileName, int compressionLevel)
  {
      clock_t const start = clock();
  
      cRess_t const ress = FIO_createCResources(dictFileName);
      int const result = FIO_compressFilename_dstFile(ress, dstFileName, srcFileName, compressionLevel);
  
      double const seconds = (double)(clock() - start) / CLOCKS_PER_SEC;
      DISPLAYLEVEL(4, "Completed in %.2f sec \n", seconds);
  
      FIO_freeCResources(ress);
      return result;
  }
  
  
  int FIO_compressMultipleFilenames(const char** inFileNamesTable, unsigned nbFiles,
                                    const char* suffix,
                                    const char* dictFileName, int compressionLevel)
  {
      int missed_files = 0;
      size_t dfnSize = FNSPACE;
      char*  dstFileName = (char*)malloc(FNSPACE);
      size_t const suffixSize = suffix ? strlen(suffix) : 0;
      cRess_t ress = FIO_createCResources(dictFileName);
  
      /* init */
      if (dstFileName==NULL) EXM_THROW(27, "FIO_compressMultipleFilenames : allocation error for dstFileName");
      if (suffix == NULL) EXM_THROW(28, "FIO_compressMultipleFilenames : dst unknown");  /* should never happen */
  
      /* loop on each file */
      if (!strcmp(suffix, stdoutmark)) {
          unsigned u;
          ress.dstFile = stdout;
          SET_BINARY_MODE(stdout);
          for (u=0; u<nbFiles; u++)
              missed_files += FIO_compressFilename_srcFile(ress, stdoutmark,
                                                           inFileNamesTable[u], compressionLevel);
          if (fclose(ress.dstFile)) EXM_THROW(29, "Write error : cannot properly close %s", stdoutmark);
      } else {
          unsigned u;
          for (u=0; u<nbFiles; u++) {
              size_t ifnSize = strlen(inFileNamesTable[u]);
              if (dfnSize <= ifnSize+suffixSize+1) { free(dstFileName); dfnSize = ifnSize + 20; dstFileName = (char*)malloc(dfnSize); }
              strcpy(dstFileName, inFileNamesTable[u]);
              strcat(dstFileName, suffix);
              missed_files += FIO_compressFilename_dstFile(ress, dstFileName,
                                                           inFileNamesTable[u], compressionLevel);
      }   }
  
      /* Close & Free */
      FIO_freeCResources(ress);
      free(dstFileName);
  
      return missed_files;
  }
  
  #endif /* #ifndef ZSTD_NOCOMPRESS */
  
  
  
  #ifndef ZSTD_NODECOMPRESS
  
  /* **************************************************************************
  *  Decompression
  ****************************************************************************/
  typedef struct {
      void*  srcBuffer;
      size_t srcBufferSize;
      void*  dstBuffer;
      size_t dstBufferSize;
      void*  dictBuffer;
      size_t dictBufferSize;
      ZSTD_DStream* dctx;
      FILE*  dstFile;
  } dRess_t;
  
  static dRess_t FIO_createDResources(const char* dictFileName)
  {
      dRess_t ress;
      memset(&ress, 0, sizeof(ress));
  
      /* Allocation */
      ress.dctx = ZSTD_createDStream();
      if (ress.dctx==NULL) EXM_THROW(60, "Can't create ZSTD_DStream");
      ress.srcBufferSize = ZSTD_DStreamInSize();
      ress.srcBuffer = malloc(ress.srcBufferSize);
      ress.dstBufferSize = ZSTD_DStreamOutSize();
      ress.dstBuffer = malloc(ress.dstBufferSize);
      if (!ress.srcBuffer || !ress.dstBuffer) EXM_THROW(61, "Allocation error : not enough memory");
  
      /* dictionary */
      ress.dictBufferSize = FIO_loadFile(&(ress.dictBuffer), dictFileName);
  
      return ress;
  }
  
  static void FIO_freeDResources(dRess_t ress)
  {
      size_t const errorCode = ZSTD_freeDStream(ress.dctx);
      if (ZSTD_isError(errorCode)) EXM_THROW(69, "Error : can't free ZSTD_DStream context resource : %s", ZSTD_getErrorName(errorCode));
      free(ress.srcBuffer);
      free(ress.dstBuffer);
      free(ress.dictBuffer);
  }
  
  
  /** FIO_fwriteSparse() :
  *   @return : storedSkips, to be provided to next call to FIO_fwriteSparse() of LZ4IO_fwriteSparseEnd() */
  static unsigned FIO_fwriteSparse(FILE* file, const void* buffer, size_t bufferSize, unsigned storedSkips)
  {
      const size_t* const bufferT = (const size_t*)buffer;   /* Buffer is supposed malloc'ed, hence aligned on size_t */
      size_t bufferSizeT = bufferSize / sizeof(size_t);
      const size_t* const bufferTEnd = bufferT + bufferSizeT;
      const size_t* ptrT = bufferT;
      static const size_t segmentSizeT = (32 KB) / sizeof(size_t);   /* 0-test re-attempted every 32 KB */
  
      if (!g_sparseFileSupport) {  /* normal write */
          size_t const sizeCheck = fwrite(buffer, 1, bufferSize, file);
          if (sizeCheck != bufferSize) EXM_THROW(70, "Write error : cannot write decoded block");
          return 0;
      }
  
      /* avoid int overflow */
      if (storedSkips > 1 GB) {
          int const seekResult = fseek(file, 1 GB, SEEK_CUR);
          if (seekResult != 0) EXM_THROW(71, "1 GB skip error (sparse file support)");
          storedSkips -= 1 GB;
      }
  
      while (ptrT < bufferTEnd) {
          size_t seg0SizeT = segmentSizeT;
          size_t nb0T;
  
          /* count leading zeros */
          if (seg0SizeT > bufferSizeT) seg0SizeT = bufferSizeT;
          bufferSizeT -= seg0SizeT;
          for (nb0T=0; (nb0T < seg0SizeT) && (ptrT[nb0T] == 0); nb0T++) ;
          storedSkips += (unsigned)(nb0T * sizeof(size_t));
  
          if (nb0T != seg0SizeT) {   /* not all 0s */
              int const seekResult = fseek(file, storedSkips, SEEK_CUR);
              if (seekResult) EXM_THROW(72, "Sparse skip error ; try --no-sparse");
              storedSkips = 0;
              seg0SizeT -= nb0T;
              ptrT += nb0T;
              {   size_t const sizeCheck = fwrite(ptrT, sizeof(size_t), seg0SizeT, file);
                  if (sizeCheck != seg0SizeT) EXM_THROW(73, "Write error : cannot write decoded block");
          }   }
          ptrT += seg0SizeT;
      }
  
      {   static size_t const maskT = sizeof(size_t)-1;
          if (bufferSize & maskT) {   /* size not multiple of sizeof(size_t) : implies end of block */
              const char* const restStart = (const char*)bufferTEnd;
              const char* restPtr = restStart;
              size_t restSize =  bufferSize & maskT;
              const char* const restEnd = restStart + restSize;
              for ( ; (restPtr < restEnd) && (*restPtr == 0); restPtr++) ;
              storedSkips += (unsigned) (restPtr - restStart);
              if (restPtr != restEnd) {
                  int seekResult = fseek(file, storedSkips, SEEK_CUR);
                  if (seekResult) EXM_THROW(74, "Sparse skip error ; try --no-sparse");
                  storedSkips = 0;
                  {   size_t const sizeCheck = fwrite(restPtr, 1, restEnd - restPtr, file);
                      if (sizeCheck != (size_t)(restEnd - restPtr)) EXM_THROW(75, "Write error : cannot write decoded end of block");
      }   }   }   }
  
      return storedSkips;
  }
  
  static void FIO_fwriteSparseEnd(FILE* file, unsigned storedSkips)
  {
      if (storedSkips-->0) {   /* implies g_sparseFileSupport>0 */
          int const seekResult = fseek(file, storedSkips, SEEK_CUR);
          if (seekResult != 0) EXM_THROW(69, "Final skip error (sparse file)\n");
          {   const char lastZeroByte[1] = { 0 };
              size_t const sizeCheck = fwrite(lastZeroByte, 1, 1, file);
              if (sizeCheck != 1) EXM_THROW(69, "Write error : cannot write last zero\n");
      }   }
  }
  
  /** FIO_decompressFrame() :
      @return : size of decoded frame
  */
  unsigned long long FIO_decompressFrame(dRess_t ress,
                                         FILE* foutput, FILE* finput, size_t alreadyLoaded)
  {
      U64 frameSize = 0;
      size_t readSize;
      U32 storedSkips = 0;
  
      ZSTD_initDStream_usingDict(ress.dctx, ress.dictBuffer, ress.dictBufferSize);
  
      /* Header loading (optional, saves one loop) */
      {   size_t const toLoad = 9 - alreadyLoaded;   /* assumption : 9 >= alreadyLoaded */
          size_t const loadedSize = fread(((char*)ress.srcBuffer) + alreadyLoaded, 1, toLoad, finput);
          readSize = alreadyLoaded + loadedSize;
      }
  
      /* Main decompression Loop */
      while (1) {
          ZSTD_inBuffer  inBuff = { ress.srcBuffer, readSize, 0 };
          ZSTD_outBuffer outBuff= { ress.dstBuffer, ress.dstBufferSize, 0 };
          size_t const toRead = ZSTD_decompressStream(ress.dctx, &outBuff, &inBuff );
          if (ZSTD_isError(toRead)) EXM_THROW(36, "Decoding error : %s", ZSTD_getErrorName(toRead));
  
          /* Write block */
          storedSkips = FIO_fwriteSparse(foutput, ress.dstBuffer, outBuff.pos, storedSkips);
          frameSize += outBuff.pos;
          DISPLAYUPDATE(2, "\rDecoded : %u MB...     ", (U32)(frameSize>>20) );
  
          if (toRead == 0) break;   /* end of frame */
          if (inBuff.size != inBuff.pos) EXM_THROW(37, "Decoding error : should consume entire input");
  
          /* Fill input buffer */
          if (toRead > ress.srcBufferSize) EXM_THROW(38, "too large block");
          readSize = fread(ress.srcBuffer, 1, toRead, finput);
          if (readSize == 0) EXM_THROW(39, "Read error : premature end");
      }
  
      FIO_fwriteSparseEnd(foutput, storedSkips);
  
      return frameSize;
  }
  
  
  /** FIO_passThrough() : just copy input into output, for compatibility with gzip -df mode
      @return : 0 (no error) */
  static unsigned FIO_passThrough(FILE* foutput, FILE* finput, void* buffer, size_t bufferSize)
  {
      size_t const blockSize = MIN (64 KB, bufferSize);
      size_t readFromInput = 1;
      unsigned storedSkips = 0;
  
      /* assumption : first 4 bytes already loaded (magic number detection), and stored within buffer */
      { size_t const sizeCheck = fwrite(buffer, 1, 4, foutput);
        if (sizeCheck != 4) EXM_THROW(50, "Pass-through write error"); }
  
      while (readFromInput) {
          readFromInput = fread(buffer, 1, blockSize, finput);
          storedSkips = FIO_fwriteSparse(foutput, buffer, readFromInput, storedSkips);
      }
  
      FIO_fwriteSparseEnd(foutput, storedSkips);
      return 0;
  }
  
  
  /** FIO_decompressSrcFile() :
      Decompression `srcFileName` into `ress.dstFile`
      @return : 0 : OK
                1 : operation not started
  */
  static int FIO_decompressSrcFile(dRess_t ress, const char* srcFileName)
  {
      unsigned long long filesize = 0;
      FILE* const dstFile = ress.dstFile;
      FILE* srcFile;
      unsigned readSomething = 0;
  
      if (UTIL_isDirectory(srcFileName)) {
          DISPLAYLEVEL(1, "zstd: %s is a directory -- ignored \n", srcFileName);
          return 1;
      }
      srcFile = FIO_openSrcFile(srcFileName);
      if (srcFile==0) return 1;
  
      /* for each frame */
      for ( ; ; ) {
          /* check magic number -> version */
          size_t const toRead = 4;
          size_t const sizeCheck = fread(ress.srcBuffer, (size_t)1, toRead, srcFile);
          if (sizeCheck==0) {
              if (readSomething==0) { DISPLAY("zstd: %s: unexpected end of file \n", srcFileName); fclose(srcFile); return 1; }  /* srcFileName is empty */
              break;   /* no more input */
          }
          readSomething = 1;
          if (sizeCheck != toRead) { DISPLAY("zstd: %s: unknown header \n", srcFileName); fclose(srcFile); return 1; }  /* srcFileName is empty */
          {   U32 const magic = MEM_readLE32(ress.srcBuffer);
              if (((magic & 0xFFFFFFF0U) != ZSTD_MAGIC_SKIPPABLE_START) & (magic != ZSTD_MAGICNUMBER)
  #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
                    & (!ZSTD_isLegacy(ress.srcBuffer, toRead))
  #endif
                  ) {
                  if ((g_overwrite) && !strcmp (srcFileName, stdinmark)) {  /* pass-through mode */
                      unsigned const result = FIO_passThrough(dstFile, srcFile, ress.srcBuffer, ress.srcBufferSize);
                      if (fclose(srcFile)) EXM_THROW(32, "zstd: %s close error", srcFileName);  /* error should never happen */
                      return result;
                  } else {
                      DISPLAYLEVEL(1, "zstd: %s: not in zstd format \n", srcFileName);
                      fclose(srcFile);
                      return 1;
          }   }   }
          filesize += FIO_decompressFrame(ress, dstFile, srcFile, toRead);
      }
  
      /* Final Status */
      DISPLAYLEVEL(2, "\r%79s\r", "");
      DISPLAYLEVEL(2, "%-20s: %llu bytes \n", srcFileName, filesize);
  
      /* Close */
      if (fclose(srcFile)) EXM_THROW(33, "zstd: %s close error", srcFileName);  /* error should never happen */
      if (g_removeSrcFile) { if (remove(srcFileName)) EXM_THROW(34, "zstd: %s: %s", srcFileName, strerror(errno)); };
      return 0;
  }
  
  
  /** FIO_decompressFile_extRess() :
      decompress `srcFileName` into `dstFileName`
      @return : 0 : OK
                1 : operation aborted (src not available, dst already taken, etc.)
  */
  static int FIO_decompressDstFile(dRess_t ress,
                                        const char* dstFileName, const char* srcFileName)
  {
      int result;
      ress.dstFile = FIO_openDstFile(dstFileName);
      if (ress.dstFile==0) return 1;
  
      result = FIO_decompressSrcFile(ress, srcFileName);
  
      if (fclose(ress.dstFile)) EXM_THROW(38, "Write error : cannot properly close %s", dstFileName);
      if (result != 0) if (remove(dstFileName)) result=1;   /* don't do anything if remove fails */
      return result;
  }
  
  
  int FIO_decompressFilename(const char* dstFileName, const char* srcFileName,
                             const char* dictFileName)
  {
      int missingFiles = 0;
      dRess_t ress = FIO_createDResources(dictFileName);
  
      missingFiles += FIO_decompressDstFile(ress, dstFileName, srcFileName);
  
      FIO_freeDResources(ress);
      return missingFiles;
  }
  
  
  #define MAXSUFFIXSIZE 8
  int FIO_decompressMultipleFilenames(const char** srcNamesTable, unsigned nbFiles,
                                      const char* suffix,
                                      const char* dictFileName)
  {
      int skippedFiles = 0;
      int missingFiles = 0;
      dRess_t ress = FIO_createDResources(dictFileName);
  
      if (suffix==NULL) EXM_THROW(70, "zstd: decompression: unknown dst");   /* should never happen */
  
      if (!strcmp(suffix, stdoutmark) || !strcmp(suffix, nulmark)) {
          unsigned u;
          ress.dstFile = FIO_openDstFile(suffix);
          if (ress.dstFile == 0) EXM_THROW(71, "cannot open %s", suffix);
          for (u=0; u<nbFiles; u++)
              missingFiles += FIO_decompressSrcFile(ress, srcNamesTable[u]);
          if (fclose(ress.dstFile)) EXM_THROW(72, "Write error : cannot properly close %s", stdoutmark);
      } else {
          size_t const suffixSize = strlen(suffix);
          size_t dfnSize = FNSPACE;
          unsigned u;
          char* dstFileName = (char*)malloc(FNSPACE);
          if (dstFileName==NULL) EXM_THROW(73, "not enough memory for dstFileName");
          for (u=0; u<nbFiles; u++) {   /* create dstFileName */
              const char* const srcFileName = srcNamesTable[u];
              size_t const sfnSize = strlen(srcFileName);
              const char* const suffixPtr = srcFileName + sfnSize - suffixSize;
              if (dfnSize+suffixSize <= sfnSize+1) {
                  free(dstFileName);
                  dfnSize = sfnSize + 20;
                  dstFileName = (char*)malloc(dfnSize);
                  if (dstFileName==NULL) EXM_THROW(74, "not enough memory for dstFileName");
              }
              if (sfnSize <= suffixSize || strcmp(suffixPtr, suffix) != 0) {
                  DISPLAYLEVEL(1, "zstd: %s: unknown suffix (%4s expected) -- ignored \n", srcFileName, suffix);
                  skippedFiles++;
                  continue;
              }
              memcpy(dstFileName, srcFileName, sfnSize - suffixSize);
              dstFileName[sfnSize-suffixSize] = '\0';
  
              missingFiles += FIO_decompressDstFile(ress, dstFileName, srcFileName);
          }
          free(dstFileName);
      }
  
      FIO_freeDResources(ress);
      return missingFiles + skippedFiles;
  }
  
  #endif /* #ifndef ZSTD_NODECOMPRESS */
  