Merge pull request #951 from lz4/lz4io

minor refactor of lz4io 

3 files changed, 205 insertions, 185 deletions

diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index 6e91e2d..4573317 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -108,7 +108,7 @@ LZ4FLIB_API const char* LZ4F_getErrorName(LZ4F_errorCode_t code);   /**< return
 
 /*-************************************
  *  Frame compression types
- **************************************/
+ ************************************* */
 /* #define LZ4F_ENABLE_OBSOLETE_ENUMS   // uncomment to enable obsolete enums */
 #ifdef LZ4F_ENABLE_OBSOLETE_ENUMS
 #  define LZ4F_OBSOLETE_ENUM(x) , LZ4F_DEPRECATE(x) = LZ4F_##x
@@ -118,7 +118,8 @@ LZ4FLIB_API const char* LZ4F_getErrorName(LZ4F_errorCode_t code);   /**< return
 
 /* The larger the block size, the (slightly) better the compression ratio,
  * though there are diminishing returns.
- * Larger blocks also increase memory usage on both compression and decompression sides. */
+ * Larger blocks also increase memory usage on both compression and decompression sides.
+ */
 typedef enum {
     LZ4F_default=0,
     LZ4F_max64KB=4,
diff --git a/programs/lz4io.c b/programs/lz4io.c
index 3ffc519..975f590 100644
--- a/programs/lz4io.c
+++ b/programs/lz4io.c
@@ -111,20 +111,20 @@ static clock_t g_time = 0;
 **************************************/
 
 struct LZ4IO_prefs_s {
-  int passThrough;
-  int overwrite;
-  int testMode;
-  int blockSizeId;
-  size_t blockSize;
-  int blockChecksum;
-  int streamChecksum;
-  int blockIndependence;
-  int sparseFileSupport;
-  int contentSizeFlag;
-  int useDictionary;
-  unsigned favorDecSpeed;
-  const char* dictionaryFilename;
-  int removeSrcFile;
+    int passThrough;
+    int overwrite;
+    int testMode;
+    int blockSizeId;
+    size_t blockSize;
+    int blockChecksum;
+    int streamChecksum;
+    int blockIndependence;
+    int sparseFileSupport;
+    int contentSizeFlag;
+    int useDictionary;
+    unsigned favorDecSpeed;
+    const char* dictionaryFilename;
+    int removeSrcFile;
 };
 
 /**************************************
@@ -325,6 +325,7 @@ static FILE* LZ4IO_openSrcFile(const char* srcFileName)
 }
 
 /** FIO_openDstFile() :
+ *  prefs is writable, because sparseFileSupport might be updated.
  *  condition : `dstFileName` must be non-NULL.
  * @result : FILE* to `dstFileName`, or NULL if it fails */
 static FILE* LZ4IO_openDstFile(LZ4IO_prefs_t* const prefs, const char* dstFileName)
@@ -333,18 +334,19 @@ static FILE* LZ4IO_openDstFile(LZ4IO_prefs_t* const prefs, const char* dstFileNa
     assert(dstFileName != NULL);
 
     if (!strcmp (dstFileName, stdoutmark)) {
-        DISPLAYLEVEL(4,"Using stdout for output\n");
+        DISPLAYLEVEL(4, "Using stdout for output \n");
         f = stdout;
         SET_BINARY_MODE(stdout);
         if (prefs->sparseFileSupport==1) {
             prefs->sparseFileSupport = 0;
-            DISPLAYLEVEL(4, "Sparse File Support is automatically disabled on stdout ; try --sparse \n");
+            DISPLAYLEVEL(4, "Sparse File Support automatically disabled on stdout ;"
+                            " to force-enable it, add --sparse command \n");
         }
     } else {
         if (!prefs->overwrite && strcmp (dstFileName, nulmark)) {  /* Check if destination file already exists */
-            f = fopen( dstFileName, "rb" );
-            if (f != NULL) {  /* dest exists, prompt for overwrite authorization */
-                fclose(f);
+            FILE* const testf = fopen( dstFileName, "rb" );
+            if (testf != NULL) {  /* dest exists, prompt for overwrite authorization */
+                fclose(testf);
                 if (g_displayLevel <= 1) {  /* No interaction possible */
                     DISPLAY("%s already exists; not overwritten  \n", dstFileName);
                     return NULL;
@@ -392,7 +394,9 @@ static int LZ4IO_LZ4_compress(const char* src, char* dst, int srcSize, int dstSi
 /* LZ4IO_compressFilename_Legacy :
  * This function is intentionally "hidden" (not published in .h)
  * It generates compressed streams using the old 'legacy' format */
-int LZ4IO_compressFilename_Legacy(LZ4IO_prefs_t* const prefs, const char* input_filename, const char* output_filename, int compressionlevel)
+int LZ4IO_compressFilename_Legacy(LZ4IO_prefs_t* const prefs,
+                                  const char* input_filename, const char* output_filename,
+                                  int compressionlevel)
 {
     typedef int (*compress_f)(const char* src, char* dst, int srcSize, int dstSize, int cLevel);
     compress_f const compressionFunction = (compressionlevel < 3) ? LZ4IO_LZ4_compress : LZ4_compress_HC;
@@ -424,23 +428,22 @@ int LZ4IO_compressFilename_Legacy(LZ4IO_prefs_t* const prefs, const char* input_
 
     /* Write Archive Header */
     LZ4IO_writeLE32(out_buff, LEGACY_MAGICNUMBER);
-    {   size_t const writeSize = fwrite(out_buff, 1, MAGICNUMBER_SIZE, foutput);
-        if (writeSize != MAGICNUMBER_SIZE)
-            EXM_THROW(22, "Write error : cannot write header");
-    }
+    if (fwrite(out_buff, 1, MAGICNUMBER_SIZE, foutput) != MAGICNUMBER_SIZE)
+        EXM_THROW(22, "Write error : cannot write header");
 
     /* Main Loop */
     while (1) {
         int outSize;
         /* Read Block */
         size_t const inSize = fread(in_buff, (size_t)1, (size_t)LEGACY_BLOCKSIZE, finput);
-        assert(inSize <= LEGACY_BLOCKSIZE);
         if (inSize == 0) break;
+        assert(inSize <= LEGACY_BLOCKSIZE);
         filesize += inSize;
 
         /* Compress Block */
         outSize = compressionFunction(in_buff, out_buff+4, (int)inSize, outBuffSize, compressionlevel);
-        compressedfilesize += outSize+4;
+        assert(outSize >= 0);
+        compressedfilesize += (unsigned long long)outSize+4;
         DISPLAYUPDATE(2, "\rRead : %i MB  ==> %.2f%%   ",
                 (int)(filesize>>20), (double)compressedfilesize/filesize*100);
 
@@ -448,9 +451,8 @@ int LZ4IO_compressFilename_Legacy(LZ4IO_prefs_t* const prefs, const char* input_
         assert(outSize > 0);
         assert(outSize < outBuffSize);
         LZ4IO_writeLE32(out_buff, (unsigned)outSize);
-        {   size_t const writeSize = fwrite(out_buff, 1, outSize+4, foutput);
-            if (writeSize != (size_t)(outSize+4))
-                EXM_THROW(24, "Write error : cannot write compressed block");
+        if (fwrite(out_buff, 1, (size_t)outSize+4, foutput) != (size_t)(outSize+4)) {
+            EXM_THROW(24, "Write error : cannot write compressed block");
     }   }
     if (ferror(finput)) EXM_THROW(25, "Error while reading %s ", input_filename);
 
@@ -537,22 +539,20 @@ typedef struct {
     LZ4F_CDict* cdict;
 } cRess_t;
 
-static void* LZ4IO_createDict(LZ4IO_prefs_t* const prefs, size_t *dictSize) {
+static void* LZ4IO_createDict(size_t* dictSize, const char* const dictFilename)
+{
     size_t readSize;
     size_t dictEnd = 0;
     size_t dictLen = 0;
     size_t dictStart;
     size_t circularBufSize = LZ4_MAX_DICT_SIZE;
-    char* circularBuf;
-    char* dictBuf;
-    const char* dictFilename = prefs->dictionaryFilename;
+    char*  circularBuf = (char*)malloc(circularBufSize);
+    char*  dictBuf;
     FILE* dictFile;
 
+    if (!circularBuf) EXM_THROW(25, "Allocation error : not enough memory for circular buffer");
     if (!dictFilename) EXM_THROW(25, "Dictionary error : no filename provided");
 
-    circularBuf = (char *) malloc(circularBufSize);
-    if (!circularBuf) EXM_THROW(25, "Allocation error : not enough memory");
-
     dictFile = LZ4IO_openSrcFile(dictFilename);
     if (!dictFile) EXM_THROW(25, "Dictionary error : could not open dictionary file");
 
@@ -582,7 +582,7 @@ static void* LZ4IO_createDict(LZ4IO_prefs_t* const prefs, size_t *dictSize) {
         circularBuf = NULL;
     } else {
         /* Otherwise, we will alloc a new buffer and copy our dict into that. */
-        dictBuf = (char *) malloc(dictLen ? dictLen : 1);
+        dictBuf = (char *)malloc(dictLen ? dictLen : 1);
         if (!dictBuf) EXM_THROW(25, "Allocation error : not enough memory");
 
         memcpy(dictBuf, circularBuf + dictStart, circularBufSize - dictStart);
@@ -595,14 +595,13 @@ static void* LZ4IO_createDict(LZ4IO_prefs_t* const prefs, size_t *dictSize) {
     return dictBuf;
 }
 
-static LZ4F_CDict* LZ4IO_createCDict(LZ4IO_prefs_t* const prefs) {
+static LZ4F_CDict* LZ4IO_createCDict(const LZ4IO_prefs_t* const prefs)
+{
     size_t dictionarySize;
     void* dictionaryBuffer;
     LZ4F_CDict* cdict;
-    if (!prefs->useDictionary) {
-        return NULL;
-    }
-    dictionaryBuffer = LZ4IO_createDict(prefs, &dictionarySize);
+    if (!prefs->useDictionary) return NULL;
+    dictionaryBuffer = LZ4IO_createDict(&dictionarySize, prefs->dictionaryFilename);
     if (!dictionaryBuffer) EXM_THROW(25, "Dictionary error : could not create dictionary");
     cdict = LZ4F_createCDict(dictionaryBuffer, dictionarySize);
     free(dictionaryBuffer);
@@ -643,6 +642,7 @@ static void LZ4IO_freeCResources(cRess_t ress)
 
 /*
  * LZ4IO_compressFilename_extRess()
+ * io_prefs is mutable, as it may update sparseFileSupport
  * result : 0 : compression completed correctly
  *          1 : missing or pb opening srcFileName
  */
@@ -653,7 +653,6 @@ LZ4IO_compressFilename_extRess(LZ4IO_prefs_t* const io_prefs, cRess_t ress,
 {
     unsigned long long filesize = 0;
     unsigned long long compressedfilesize = 0;
-    FILE* srcFile;
     FILE* dstFile;
     void* const srcBuffer = ress.srcBuffer;
     void* const dstBuffer = ress.dstBuffer;
@@ -664,13 +663,12 @@ LZ4IO_compressFilename_extRess(LZ4IO_prefs_t* const io_prefs, cRess_t ress,
     LZ4F_preferences_t prefs;
 
     /* Init */
-    srcFile = LZ4IO_openSrcFile(srcFileName);
+    FILE* const srcFile = LZ4IO_openSrcFile(srcFileName);
     if (srcFile == NULL) return 1;
     dstFile = LZ4IO_openDstFile(io_prefs, dstFileName);
     if (dstFile == NULL) { fclose(srcFile); return 1; }
     memset(&prefs, 0, sizeof(prefs));
 
-
     /* Set compression parameters */
     prefs.autoFlush = 1;
     prefs.compressionLevel = compressionLevel;
@@ -694,41 +692,41 @@ LZ4IO_compressFilename_extRess(LZ4IO_prefs_t* const io_prefs, cRess_t ress,
     /* single-block file */
     if (readSize < blockSize) {
         /* Compress in single pass */
-        size_t cSize = LZ4F_compressFrame_usingCDict(ctx, dstBuffer, dstBufferSize, srcBuffer, readSize, ress.cdict, &prefs);
-        if (LZ4F_isError(cSize)) EXM_THROW(31, "Compression failed : %s", LZ4F_getErrorName(cSize));
+        size_t const cSize = LZ4F_compressFrame_usingCDict(ctx, dstBuffer, dstBufferSize, srcBuffer, readSize, ress.cdict, &prefs);
+        if (LZ4F_isError(cSize))
+            EXM_THROW(31, "Compression failed : %s", LZ4F_getErrorName(cSize));
         compressedfilesize = cSize;
         DISPLAYUPDATE(2, "\rRead : %u MB   ==> %.2f%%   ",
                       (unsigned)(filesize>>20), (double)compressedfilesize/(filesize+!filesize)*100);   /* avoid division by zero */
 
         /* Write Block */
-        {   size_t const sizeCheck = fwrite(dstBuffer, 1, cSize, dstFile);
-            if (sizeCheck!=cSize) EXM_THROW(32, "Write error : cannot write compressed block");
+        if (fwrite(dstBuffer, 1, cSize, dstFile) != cSize) {
+            EXM_THROW(32, "Write error : failed writing single-block compressed frame");
     }   }
 
     else
 
     /* multiple-blocks file */
     {
-        /* Write Archive Header */
-        size_t headerSize = LZ4F_compressBegin_usingCDict(ctx, dstBuffer, dstBufferSize, ress.cdict, &prefs);
+        /* Write Frame Header */
+        size_t const headerSize = LZ4F_compressBegin_usingCDict(ctx, dstBuffer, dstBufferSize, ress.cdict, &prefs);
         if (LZ4F_isError(headerSize)) EXM_THROW(33, "File header generation failed : %s", LZ4F_getErrorName(headerSize));
-        { size_t const sizeCheck = fwrite(dstBuffer, 1, headerSize, dstFile);
-          if (sizeCheck!=headerSize) EXM_THROW(34, "Write error : cannot write header"); }
+        if (fwrite(dstBuffer, 1, headerSize, dstFile) != headerSize)
+            EXM_THROW(34, "Write error : cannot write header");
         compressedfilesize += headerSize;
 
-        /* Main Loop */
+        /* Main Loop - one block at a time */
         while (readSize>0) {
-            size_t outSize;
-
-            /* Compress Block */
-            outSize = LZ4F_compressUpdate(ctx, dstBuffer, dstBufferSize, srcBuffer, readSize, NULL);
-            if (LZ4F_isError(outSize)) EXM_THROW(35, "Compression failed : %s", LZ4F_getErrorName(outSize));
+            size_t const outSize = LZ4F_compressUpdate(ctx, dstBuffer, dstBufferSize, srcBuffer, readSize, NULL);
+            if (LZ4F_isError(outSize))
+                EXM_THROW(35, "Compression failed : %s", LZ4F_getErrorName(outSize));
             compressedfilesize += outSize;
-            DISPLAYUPDATE(2, "\rRead : %u MB   ==> %.2f%%   ", (unsigned)(filesize>>20), (double)compressedfilesize/filesize*100);
+            DISPLAYUPDATE(2, "\rRead : %u MB   ==> %.2f%%   ",
+                        (unsigned)(filesize>>20), (double)compressedfilesize/filesize*100);
 
             /* Write Block */
-            { size_t const sizeCheck = fwrite(dstBuffer, 1, outSize, dstFile);
-              if (sizeCheck!=outSize) EXM_THROW(36, "Write error : cannot write compressed block"); }
+            if (fwrite(dstBuffer, 1, outSize, dstFile) != outSize)
+                EXM_THROW(36, "Write error : cannot write compressed block");
 
             /* Read next block */
             readSize  = fread(srcBuffer, (size_t)1, (size_t)blockSize, srcFile);
@@ -736,18 +734,18 @@ LZ4IO_compressFilename_extRess(LZ4IO_prefs_t* const io_prefs, cRess_t ress,
         }
         if (ferror(srcFile)) EXM_THROW(37, "Error reading %s ", srcFileName);
 
-        /* End of Stream mark */
-        headerSize = LZ4F_compressEnd(ctx, dstBuffer, dstBufferSize, NULL);
-        if (LZ4F_isError(headerSize)) EXM_THROW(38, "End of file generation failed : %s", LZ4F_getErrorName(headerSize));
-
-        { size_t const sizeCheck = fwrite(dstBuffer, 1, headerSize, dstFile);
-          if (sizeCheck!=headerSize) EXM_THROW(39, "Write error : cannot write end of stream"); }
-        compressedfilesize += headerSize;
-    }
+        /* End of Frame mark */
+        {   size_t const endSize = LZ4F_compressEnd(ctx, dstBuffer, dstBufferSize, NULL);
+            if (LZ4F_isError(endSize))
+                EXM_THROW(38, "End of frame error : %s", LZ4F_getErrorName(endSize));
+            if (fwrite(dstBuffer, 1, endSize, dstFile) != endSize)
+                EXM_THROW(39, "Write error : cannot write end of frame");
+            compressedfilesize += endSize;
+    }   }
 
     /* Release file handlers */
     fclose (srcFile);
-    if (strcmp(dstFileName,stdoutmark)) fclose (dstFile);   /* do not close stdout */
+    if (strcmp(dstFileName,stdoutmark)) fclose (dstFile);  /* do not close stdout */
 
     /* Copy owner, file permissions and modification time */
     {   stat_t statbuf;
@@ -861,7 +859,11 @@ static unsigned LZ4IO_readLE32 (const void* s)
 }
 
 
-static unsigned LZ4IO_fwriteSparse(LZ4IO_prefs_t* const prefs, FILE* file, const void* buffer, size_t bufferSize, unsigned storedSkips)
+static unsigned
+LZ4IO_fwriteSparse(FILE* file,
+                   const void* buffer, size_t bufferSize,
+                   int sparseFileSupport,
+                   unsigned storedSkips)
 {
     const size_t sizeT = sizeof(size_t);
     const size_t maskT = sizeT -1 ;
@@ -871,7 +873,7 @@ static unsigned LZ4IO_fwriteSparse(LZ4IO_prefs_t* const prefs, FILE* file, const
     const size_t* const bufferTEnd = bufferT + bufferSizeT;
     const size_t segmentSizeT = (32 KB) / sizeT;
 
-    if (!prefs->sparseFileSupport) {  /* normal write */
+    if (!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;
@@ -919,7 +921,7 @@ static unsigned LZ4IO_fwriteSparse(LZ4IO_prefs_t* const prefs, FILE* file, const
             int const seekResult = UTIL_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);
+            {   size_t const sizeCheck = fwrite(restPtr, 1, (size_t)(restEnd - restPtr), file);
                 if (sizeCheck != (size_t)(restEnd - restPtr)) EXM_THROW(75, "Write error : cannot write decoded end of block");
         }   }
     }
@@ -929,18 +931,18 @@ static unsigned LZ4IO_fwriteSparse(LZ4IO_prefs_t* const prefs, FILE* file, const
 
 static void LZ4IO_fwriteSparseEnd(FILE* file, unsigned storedSkips)
 {
-    if (storedSkips>0) {   /* implies g_sparseFileSupport>0 */
-        int const seekResult = UTIL_fseek(file, storedSkips-1, 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");
-    }   }
+    if (storedSkips>0) {   /* implies sparseFileSupport>0 */
+        const char lastZeroByte[1] = { 0 };
+        if (UTIL_fseek(file, storedSkips-1, SEEK_CUR) != 0)
+            EXM_THROW(69, "Final skip error (sparse file)\n");
+        if (fwrite(lastZeroByte, 1, 1, file) != 1)
+            EXM_THROW(69, "Write error : cannot write last zero\n");
+    }
 }
 
 
 static unsigned g_magicRead = 0;   /* out-parameter of LZ4IO_decodeLegacyStream() */
-static unsigned long long LZ4IO_decodeLegacyStream(LZ4IO_prefs_t* const prefs, FILE* finput, FILE* foutput)
+static unsigned long long LZ4IO_decodeLegacyStream(FILE* finput, FILE* foutput, const LZ4IO_prefs_t* prefs)
 {
     unsigned long long streamSize = 0;
     unsigned storedSkips = 0;
@@ -974,7 +976,7 @@ static unsigned long long LZ4IO_decodeLegacyStream(LZ4IO_prefs_t* const prefs, F
             if (decodeSize < 0) EXM_THROW(53, "Decoding Failed ! Corrupted input detected !");
             streamSize += (unsigned long long)decodeSize;
             /* Write Block */
-            storedSkips = LZ4IO_fwriteSparse(prefs, foutput, out_buff, (size_t)decodeSize, storedSkips); /* success or die */
+            storedSkips = LZ4IO_fwriteSparse(foutput, out_buff, (size_t)decodeSize, prefs->sparseFileSupport, storedSkips); /* success or die */
     }   }
     if (ferror(finput)) EXM_THROW(54, "Read error : ferror");
 
@@ -1000,19 +1002,20 @@ typedef struct {
     size_t dictBufferSize;
 } dRess_t;
 
-static void LZ4IO_loadDDict(LZ4IO_prefs_t* const prefs, dRess_t* ress) {
+static void LZ4IO_loadDDict(dRess_t* ress, const LZ4IO_prefs_t* const prefs)
+{
     if (!prefs->useDictionary) {
         ress->dictBuffer = NULL;
         ress->dictBufferSize = 0;
         return;
     }
 
-    ress->dictBuffer = LZ4IO_createDict(prefs, &ress->dictBufferSize);
+    ress->dictBuffer = LZ4IO_createDict(&ress->dictBufferSize, prefs->dictionaryFilename);
     if (!ress->dictBuffer) EXM_THROW(25, "Dictionary error : could not create dictionary");
 }
 
 static const size_t LZ4IO_dBufferSize = 64 KB;
-static dRess_t LZ4IO_createDResources(LZ4IO_prefs_t* const prefs)
+static dRess_t LZ4IO_createDResources(const LZ4IO_prefs_t* const prefs)
 {
     dRess_t ress;
 
@@ -1027,7 +1030,7 @@ static dRess_t LZ4IO_createDResources(LZ4IO_prefs_t* const prefs)
     ress.dstBuffer = malloc(ress.dstBufferSize);
     if (!ress.srcBuffer || !ress.dstBuffer) EXM_THROW(61, "Allocation error : not enough memory");
 
-    LZ4IO_loadDDict(prefs, &ress);
+    LZ4IO_loadDDict(&ress, prefs);
 
     ress.dstFile = NULL;
     return ress;
@@ -1043,7 +1046,10 @@ static void LZ4IO_freeDResources(dRess_t ress)
 }
 
 
-static unsigned long long LZ4IO_decompressLZ4F(LZ4IO_prefs_t* const prefs, dRess_t ress, FILE* srcFile, FILE* dstFile)
+static unsigned long long
+LZ4IO_decompressLZ4F(dRess_t ress,
+                     FILE* const srcFile, FILE* const dstFile,
+                     const LZ4IO_prefs_t* const prefs)
 {
     unsigned long long filesize = 0;
     LZ4F_errorCode_t nextToLoad;
@@ -1079,7 +1085,7 @@ static unsigned long long LZ4IO_decompressLZ4F(LZ4IO_prefs_t* const prefs, dRess
             /* Write Block */
             if (decodedBytes) {
                 if (!prefs->testMode)
-                    storedSkips = LZ4IO_fwriteSparse(prefs, dstFile, ress.dstBuffer, decodedBytes, storedSkips);
+                    storedSkips = LZ4IO_fwriteSparse(dstFile, ress.dstBuffer, decodedBytes, prefs->sparseFileSupport, storedSkips);
                 filesize += decodedBytes;
                 DISPLAYUPDATE(2, "\rDecompressed : %u MB  ", (unsigned)(filesize>>20));
             }
@@ -1097,22 +1103,30 @@ static unsigned long long LZ4IO_decompressLZ4F(LZ4IO_prefs_t* const prefs, dRess
 }
 
 
+/* LZ4IO_passThrough:
+ * just output the same content as input, no decoding.
+ * This is a capability of zcat, and by extension lz4cat
+ * MNstore : contain the first MAGICNUMBER_SIZE bytes already read from finput
+ */
 #define PTSIZE  (64 KB)
 #define PTSIZET (PTSIZE / sizeof(size_t))
-static unsigned long long LZ4IO_passThrough(LZ4IO_prefs_t* const prefs, FILE* finput, FILE* foutput, unsigned char MNstore[MAGICNUMBER_SIZE])
+static unsigned long long
+LZ4IO_passThrough(FILE* finput, FILE* foutput,
+                  unsigned char MNstore[MAGICNUMBER_SIZE],
+                  int sparseFileSupport)
 {
 	size_t buffer[PTSIZET];
     size_t readBytes = 1;
     unsigned long long total = MAGICNUMBER_SIZE;
     unsigned storedSkips = 0;
 
-    size_t const sizeCheck = fwrite(MNstore, 1, MAGICNUMBER_SIZE, foutput);
-    if (sizeCheck != MAGICNUMBER_SIZE) EXM_THROW(50, "Pass-through write error");
-
+    if (fwrite(MNstore, 1, MAGICNUMBER_SIZE, foutput) != MAGICNUMBER_SIZE) {
+        EXM_THROW(50, "Pass-through write error");
+    }
     while (readBytes) {
-        readBytes = fread(buffer, 1, PTSIZE, finput);
+        readBytes = fread(buffer, 1, sizeof(buffer), finput);
         total += readBytes;
-        storedSkips = LZ4IO_fwriteSparse(prefs, foutput, buffer, readBytes, storedSkips);
+        storedSkips = LZ4IO_fwriteSparse(foutput, buffer, readBytes, sparseFileSupport, storedSkips);
     }
     if (ferror(finput)) EXM_THROW(51, "Read Error");
 
@@ -1139,7 +1153,10 @@ static int fseek_u32(FILE *fp, unsigned offset, int where)
 }
 
 #define ENDOFSTREAM ((unsigned long long)-1)
-static unsigned long long selectDecoder(LZ4IO_prefs_t* const prefs, dRess_t ress, FILE* finput, FILE* foutput)
+static unsigned long long
+selectDecoder(dRess_t ress,
+              FILE* finput, FILE* foutput,
+              const LZ4IO_prefs_t* const prefs)
 {
     unsigned char MNstore[MAGICNUMBER_SIZE];
     unsigned magicNumber;
@@ -1165,10 +1182,10 @@ static unsigned long long selectDecoder(LZ4IO_prefs_t* const prefs, dRess_t ress
     switch(magicNumber)
     {
     case LZ4IO_MAGICNUMBER:
-        return LZ4IO_decompressLZ4F(prefs, ress, finput, foutput);
+        return LZ4IO_decompressLZ4F(ress, finput, foutput, prefs);
     case LEGACY_MAGICNUMBER:
         DISPLAYLEVEL(4, "Detected : Legacy format \n");
-        return LZ4IO_decodeLegacyStream(prefs, finput, foutput);
+        return LZ4IO_decodeLegacyStream(finput, foutput, prefs);
     case LZ4IO_SKIPPABLE0:
         DISPLAYLEVEL(4, "Skipping detected skippable area \n");
         {   size_t const nbReadBytes = fread(MNstore, 1, 4, finput);
@@ -1187,7 +1204,7 @@ static unsigned long long selectDecoder(LZ4IO_prefs_t* const prefs, dRess_t ress
             /* Wrong magic number at the beginning of 1st stream */
             if (!prefs->testMode && prefs->overwrite && prefs->passThrough) {
                 nbFrames = 0;
-                return LZ4IO_passThrough(prefs, finput, foutput, MNstore);
+                return LZ4IO_passThrough(finput, foutput, MNstore, prefs->sparseFileSupport);
             }
             EXM_THROW(44,"Unrecognized header : file cannot be decoded");
         }
@@ -1202,7 +1219,10 @@ static unsigned long long selectDecoder(LZ4IO_prefs_t* const prefs, dRess_t ress
 }
 
 
-static int LZ4IO_decompressSrcFile(LZ4IO_prefs_t* const prefs, dRess_t ress, const char* input_filename, const char* output_filename)
+static int
+LZ4IO_decompressSrcFile(dRess_t ress,
+                        const char* input_filename, const char* output_filename,
+                        const LZ4IO_prefs_t* const prefs)
 {
     FILE* const foutput = ress.dstFile;
     unsigned long long filesize = 0;
@@ -1210,11 +1230,12 @@ static int LZ4IO_decompressSrcFile(LZ4IO_prefs_t* const prefs, dRess_t ress, con
     /* Init */
     FILE* const finput = LZ4IO_openSrcFile(input_filename);
     if (finput==NULL) return 1;
+    assert(foutput != NULL);
 
     /* Loop over multiple streams */
     for ( ; ; ) {  /* endless loop, see break condition */
         unsigned long long const decodedSize =
-                        selectDecoder(prefs, ress, finput, foutput);
+                        selectDecoder(ress, finput, foutput, prefs);
         if (decodedSize == ENDOFSTREAM) break;
         filesize += decodedSize;
     }
@@ -1235,7 +1256,10 @@ static int LZ4IO_decompressSrcFile(LZ4IO_prefs_t* const prefs, dRess_t ress, con
 }
 
 
-static int LZ4IO_decompressDstFile(LZ4IO_prefs_t* const prefs, dRess_t ress, const char* input_filename, const char* output_filename)
+static int
+LZ4IO_decompressDstFile(LZ4IO_prefs_t* const prefs,
+                        dRess_t ress,
+                        const char* input_filename, const char* output_filename)
 {
     stat_t statbuf;
     int stat_result = 0;
@@ -1247,7 +1271,7 @@ static int LZ4IO_decompressDstFile(LZ4IO_prefs_t* const prefs, dRess_t ress, con
         stat_result = 1;
 
     ress.dstFile = foutput;
-    LZ4IO_decompressSrcFile(prefs, ress, input_filename, output_filename);
+    LZ4IO_decompressSrcFile(ress, input_filename, output_filename, prefs);
 
     fclose(foutput);
 
@@ -1298,7 +1322,7 @@ int LZ4IO_decompressMultipleFilenames(LZ4IO_prefs_t* const prefs,
         size_t const ifnSize = strlen(inFileNamesTable[i]);
         const char* const suffixPtr = inFileNamesTable[i] + ifnSize - suffixSize;
         if (!strcmp(suffix, stdoutmark)) {
-            missingFiles += LZ4IO_decompressSrcFile(prefs, ress, inFileNamesTable[i], stdoutmark);
+            missingFiles += LZ4IO_decompressSrcFile(ress, inFileNamesTable[i], stdoutmark, prefs);
             continue;
         }
         if (ofnSize <= ifnSize-suffixSize+1) {
@@ -1351,7 +1375,7 @@ typedef struct {
     unsigned short allContentSize;
 } LZ4IO_cFileInfo_t;
 
-#define LZ4IO_INIT_CFILEINFO   { NULL, 0ULL, 0, LZ4IO_INIT_FRAMEINFO, 1, 1, 1 }
+#define LZ4IO_INIT_CFILEINFO  { NULL, 0ULL, 0, LZ4IO_INIT_FRAMEINFO, 1, 1, 1 }
 
 typedef enum { LZ4IO_LZ4F_OK, LZ4IO_format_not_known, LZ4IO_not_a_file } LZ4IO_infoResult;
 
@@ -1363,9 +1387,11 @@ static const char * LZ4IO_frameTypeNames[] = {"LZ4Frame", "LegacyFrame", "Skippa
    returns 0 in case it can't succesfully skip block data.
    Assumes SEEK_CUR after frame header.
  */
-static unsigned long long LZ4IO_skipBlocksData(FILE* finput,
-        const LZ4F_blockChecksum_t blockChecksumFlag,
-        const LZ4F_contentChecksum_t contentChecksumFlag) {
+static unsigned long long
+LZ4IO_skipBlocksData(FILE* finput,
+               const LZ4F_blockChecksum_t blockChecksumFlag,
+               const LZ4F_contentChecksum_t contentChecksumFlag)
+{
     unsigned char blockInfo[LZ4F_BLOCK_HEADER_SIZE];
     unsigned long long totalBlocksSize = 0;
     for (;;) {
@@ -1374,8 +1400,7 @@ static unsigned long long LZ4IO_skipBlocksData(FILE* finput,
             return 0;
         }
         totalBlocksSize += LZ4F_BLOCK_HEADER_SIZE;
-        {
-            const unsigned long nextCBlockSize = LZ4IO_readLE32(&blockInfo) & 0x7FFFFFFFU;
+        {   const unsigned long nextCBlockSize = LZ4IO_readLE32(&blockInfo) & 0x7FFFFFFFU;
             const unsigned long nextBlock = nextCBlockSize + (blockChecksumFlag * LZ4F_BLOCK_CHECKSUM_SIZE);
             if (nextCBlockSize == 0) {
                 /* Reached EndMark */
@@ -1390,11 +1415,9 @@ static unsigned long long LZ4IO_skipBlocksData(FILE* finput,
             }
             totalBlocksSize += nextBlock;
             /* skip to the next block */
-            if (UTIL_fseek(finput, nextBlock, SEEK_CUR) != 0) {
-                return 0;
-            }
-        }
-    }
+            assert(nextBlock < LONG_MAX);
+            if (UTIL_fseek(finput, (long)nextBlock, SEEK_CUR) != 0) return 0;
+    }   }
     return totalBlocksSize;
 }
 
@@ -1405,7 +1428,8 @@ static unsigned long long LZ4IO_skipBlocksData(FILE* finput,
    This works as long as legacy block header size = magic number size.
    Assumes SEEK_CUR after frame header.
  */
-static unsigned long long LZ4IO_skipLegacyBlocksData(FILE* finput) {
+static unsigned long long LZ4IO_skipLegacyBlocksData(FILE* finput)
+{
     unsigned char blockInfo[LZIO_LEGACY_BLOCK_HEADER_SIZE];
     unsigned long long totalBlocksSize = 0;
     LZ4IO_STATIC_ASSERT(LZIO_LEGACY_BLOCK_HEADER_SIZE == MAGICNUMBER_SIZE);
@@ -1428,14 +1452,15 @@ static unsigned long long LZ4IO_skipLegacyBlocksData(FILE* finput) {
             /* skip to the next block */
             if (UTIL_fseek(finput, nextCBlockSize, SEEK_CUR) != 0) {
                 return 0;
-            }
-        }
-    }
+    }   }   }
     return totalBlocksSize;
 }
 
-/* buffer : must be a valid memory area of at least 4 bytes */
-const char* LZ4IO_blockTypeID(int sizeID, int blockMode, char* buffer) {
+/* LZ4IO_blockTypeID:
+ * return human-readable block type, following command line convention
+ * buffer : must be a valid memory area of at least 4 bytes */
+const char* LZ4IO_blockTypeID(LZ4F_blockSizeID_t sizeID, LZ4F_blockMode_t blockMode, char buffer[4])
+{
     buffer[0] = 'B';
     assert(sizeID >= 4); assert(sizeID <= 7);
     buffer[1] = (char)(sizeID + '0');
@@ -1445,7 +1470,8 @@ const char* LZ4IO_blockTypeID(int sizeID, int blockMode, char* buffer) {
 }
 
 /* buffer : must be valid memory area of at least 10 bytes */
-static const char* LZ4IO_toHuman(long double size, char *buf) {
+static const char* LZ4IO_toHuman(long double size, char *buf)
+{
     const char units[] = {"\0KMGTPEZY"};
     size_t i = 0;
     for (; size >= 1024; i++) size /= 1024;
@@ -1454,14 +1480,15 @@ static const char* LZ4IO_toHuman(long double size, char *buf) {
 }
 
 /* Get filename without path prefix */
-static const char* LZ4IO_baseName(const char* input_filename) {
+static const char* LZ4IO_baseName(const char* input_filename)
+{
     const char* b = strrchr(input_filename, '/');
     if (!b) b = strrchr(input_filename, '\\');
     if (!b) return input_filename;
     return b + 1;
 }
 
-/* Report frame/s information in verbose mode.
+/* Report frame/s information (--list) in verbose mode (-v).
  * Will populate file info with fileName and frameSummary where applicable.
  * - TODO :
  *  + report nb of blocks, hence max. possible decompressed size (when not reported in header)
@@ -1480,11 +1507,12 @@ LZ4IO_getCompressedFileInfo(LZ4IO_cFileInfo_t* cfinfo, const char* input_filenam
         LZ4IO_frameInfo_t frameInfo = LZ4IO_INIT_FRAMEINFO;
         unsigned magicNumber;
         /* Get MagicNumber */
-        size_t nbReadBytes = fread(buffer, 1, MAGICNUMBER_SIZE, finput);
-        if (nbReadBytes == 0) { break; } /* EOF */
-        result = LZ4IO_format_not_known;  /* default result (error) */
-        if (nbReadBytes != MAGICNUMBER_SIZE)
-            EXM_THROW(40, "Unrecognized header : Magic Number unreadable");
+        {   size_t const nbReadBytes = fread(buffer, 1, MAGICNUMBER_SIZE, finput);
+            if (nbReadBytes == 0) { break; } /* EOF */
+            result = LZ4IO_format_not_known;  /* default result (error) */
+            if (nbReadBytes != MAGICNUMBER_SIZE) {
+                EXM_THROW(40, "Unrecognized header : Magic Number unreadable");
+        }   }
         magicNumber = LZ4IO_readLE32(buffer);   /* Little Endian format */
         if (LZ4IO_isSkippableMagicNumber(magicNumber))
             magicNumber = LZ4IO_SKIPPABLE0;   /* fold skippable magic numbers */
@@ -1497,56 +1525,49 @@ LZ4IO_getCompressedFileInfo(LZ4IO_cFileInfo_t* cfinfo, const char* input_filenam
                 if (!readBytes || ferror(finput)) EXM_THROW(71, "Error reading %s", input_filename);
             }
             {   size_t hSize = LZ4F_headerSize(&buffer, LZ4F_HEADER_SIZE_MIN);
-                if (!LZ4F_isError(hSize)) {
-                    if (hSize > (LZ4F_HEADER_SIZE_MIN + MAGICNUMBER_SIZE)) {
-                        /* We've already read LZ4F_HEADER_SIZE_MIN so read any extra until hSize*/
-                        const size_t readBytes = fread(buffer + LZ4F_HEADER_SIZE_MIN, 1, hSize - LZ4F_HEADER_SIZE_MIN, finput);
-                        if (!readBytes || ferror(finput)) EXM_THROW(72, "Error reading %s", input_filename);
-                    }
-                    /* Create decompression context */
-                    {   LZ4F_dctx* dctx;
-                        unsigned isError = LZ4F_isError(LZ4F_createDecompressionContext(&dctx, LZ4F_VERSION));
-                        if (!isError) {
-                            isError = LZ4F_isError(LZ4F_getFrameInfo(dctx, &frameInfo.lz4FrameInfo, buffer, &hSize));
-                            LZ4F_freeDecompressionContext(dctx);
-                            if (!isError) {
-                                if ((cfinfo->frameSummary.lz4FrameInfo.blockSizeID != frameInfo.lz4FrameInfo.blockSizeID ||
-                                        cfinfo->frameSummary.lz4FrameInfo.blockMode != frameInfo.lz4FrameInfo.blockMode)
-                                        && cfinfo->frameCount != 0)
-                                    cfinfo->eqBlockTypes = 0;
-                                {   const unsigned long long totalBlocksSize = LZ4IO_skipBlocksData(finput,
-                                            frameInfo.lz4FrameInfo.blockChecksumFlag,
-                                            frameInfo.lz4FrameInfo.contentChecksumFlag);
-                                    if (totalBlocksSize) {
-                                        char bTypeBuffer[5];
-                                        LZ4IO_blockTypeID(frameInfo.lz4FrameInfo.blockSizeID, frameInfo.lz4FrameInfo.blockMode, bTypeBuffer);
-                                        DISPLAYLEVEL(3, "    %6llu %14s %5s %8s",
-                                                     cfinfo->frameCount + 1,
-                                                     LZ4IO_frameTypeNames[frameInfo.frameType],
-                                                     bTypeBuffer,
-                                                     frameInfo.lz4FrameInfo.contentChecksumFlag ? "XXH32" : "-");
-                                        if (frameInfo.lz4FrameInfo.contentSize) {
-                                            {   double const ratio = (double)(totalBlocksSize + hSize) / frameInfo.lz4FrameInfo.contentSize * 100;
-                                                DISPLAYLEVEL(3, " %20llu %20llu %9.2f%%\n",
-                                                             totalBlocksSize + hSize,
-                                                             frameInfo.lz4FrameInfo.contentSize,
-                                                             ratio);
-                                            }
-                                            /* Now we've consumed frameInfo we can use it to store the total contentSize */
-                                            frameInfo.lz4FrameInfo.contentSize += cfinfo->frameSummary.lz4FrameInfo.contentSize;
-                                        }
-                                        else {
-                                            DISPLAYLEVEL(3, " %20llu %20s %9s \n", totalBlocksSize + hSize, "-", "-");
-                                            cfinfo->allContentSize = 0;
-                                        }
-                                        result = LZ4IO_LZ4F_OK;
+                if (LZ4F_isError(hSize)) break;
+                if (hSize > (LZ4F_HEADER_SIZE_MIN + MAGICNUMBER_SIZE)) {
+                    /* We've already read LZ4F_HEADER_SIZE_MIN so read any extra until hSize*/
+                    const size_t readBytes = fread(buffer + LZ4F_HEADER_SIZE_MIN, 1, hSize - LZ4F_HEADER_SIZE_MIN, finput);
+                    if (!readBytes || ferror(finput)) EXM_THROW(72, "Error reading %s", input_filename);
+                }
+                /* Create decompression context */
+                {   LZ4F_dctx* dctx;
+                    if ( LZ4F_isError(LZ4F_createDecompressionContext(&dctx, LZ4F_VERSION)) ) break;
+                    {   unsigned const frameInfoError = LZ4F_isError(LZ4F_getFrameInfo(dctx, &frameInfo.lz4FrameInfo, buffer, &hSize));
+                        LZ4F_freeDecompressionContext(dctx);
+                        if (frameInfoError) break;
+                        if ((cfinfo->frameSummary.lz4FrameInfo.blockSizeID != frameInfo.lz4FrameInfo.blockSizeID ||
+                                cfinfo->frameSummary.lz4FrameInfo.blockMode != frameInfo.lz4FrameInfo.blockMode)
+                                && cfinfo->frameCount != 0)
+                            cfinfo->eqBlockTypes = 0;
+                        {   const unsigned long long totalBlocksSize = LZ4IO_skipBlocksData(finput,
+                                    frameInfo.lz4FrameInfo.blockChecksumFlag,
+                                    frameInfo.lz4FrameInfo.contentChecksumFlag);
+                            if (totalBlocksSize) {
+                                char bTypeBuffer[5];
+                                LZ4IO_blockTypeID(frameInfo.lz4FrameInfo.blockSizeID, frameInfo.lz4FrameInfo.blockMode, bTypeBuffer);
+                                DISPLAYLEVEL(3, "    %6llu %14s %5s %8s",
+                                             cfinfo->frameCount + 1,
+                                             LZ4IO_frameTypeNames[frameInfo.frameType],
+                                             bTypeBuffer,
+                                             frameInfo.lz4FrameInfo.contentChecksumFlag ? "XXH32" : "-");
+                                if (frameInfo.lz4FrameInfo.contentSize) {
+                                    {   double const ratio = (double)(totalBlocksSize + hSize) / frameInfo.lz4FrameInfo.contentSize * 100;
+                                        DISPLAYLEVEL(3, " %20llu %20llu %9.2f%%\n",
+                                                     totalBlocksSize + hSize,
+                                                     frameInfo.lz4FrameInfo.contentSize,
+                                                     ratio);
                                     }
+                                    /* Now we've consumed frameInfo we can use it to store the total contentSize */
+                                    frameInfo.lz4FrameInfo.contentSize += cfinfo->frameSummary.lz4FrameInfo.contentSize;
                                 }
-                            }
-                        }
-                    }
-                }
-            }
+                                else {
+                                    DISPLAYLEVEL(3, " %20llu %20s %9s \n", totalBlocksSize + hSize, "-", "-");
+                                    cfinfo->allContentSize = 0;
+                                }
+                                result = LZ4IO_LZ4F_OK;
+            }   }   }   }   }
             break;
         case LEGACY_MAGICNUMBER:
             frameInfo.frameType = legacyFrame;
@@ -1569,7 +1590,7 @@ LZ4IO_getCompressedFileInfo(LZ4IO_cFileInfo_t* cfinfo, const char* input_filenam
             if (cfinfo->frameSummary.frameType != skippableFrame && cfinfo->frameCount != 0) cfinfo->eqFrameTypes = 0;
             cfinfo->eqBlockTypes = 0;
             cfinfo->allContentSize = 0;
-            {   nbReadBytes = fread(buffer, 1, 4, finput);
+            {   size_t const nbReadBytes = fread(buffer, 1, 4, finput);
                 if (nbReadBytes != 4)
                     EXM_THROW(42, "Stream error : skippable size unreadable");
             }
@@ -1594,12 +1615,10 @@ LZ4IO_getCompressedFileInfo(LZ4IO_cFileInfo_t* cfinfo, const char* input_filenam
             }
         break;
         }
-        if (result != LZ4IO_LZ4F_OK) {
-            break;
-        }
+        if (result != LZ4IO_LZ4F_OK) break;
         cfinfo->frameSummary = frameInfo;
         cfinfo->frameCount++;
-    }
+    }  /* while (!feof(finput)) */
     fclose(finput);
     return result;
 }
diff --git a/tests/Makefile b/tests/Makefile
index 476849e..6eee132 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -420,7 +420,7 @@ test-lz4-hugefile: lz4 datagen
 
 test-lz4-testmode: lz4 datagen
 	@echo "\n ---- bench mode ----"
-	$(LZ4) -bi1
+	$(LZ4) -bi0
 	@echo "\n ---- test mode ----"
 	! $(DATAGEN) | $(LZ4) -t
 	! $(DATAGEN) | $(LZ4) -tf