Merge pull request #670 from lz4/dev

v1.9.0

8 files changed, 418 insertions, 240 deletions

diff --git a/programs/Makefile b/programs/Makefile
index bd33d9b..92fd683 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -94,7 +94,7 @@ lz4.1: lz4.1.md $(LIBVER_SRC)
 man: lz4.1
 
 clean-man:
-	rm lz4.1
+	$(RM) lz4.1
 
 preview-man: clean-man man
 	man ./lz4.1
@@ -109,7 +109,7 @@ clean:
 #-----------------------------------------------------------------------------
 # make install is validated only for Linux, OSX, BSD, Hurd and Solaris targets
 #-----------------------------------------------------------------------------
-ifneq (,$(filter $(shell uname),Linux Darwin GNU/kFreeBSD GNU OpenBSD FreeBSD NetBSD DragonFly SunOS Haiku MidnightBSD))
+ifneq (,$(filter $(shell uname),Linux Darwin GNU/kFreeBSD GNU OpenBSD FreeBSD NetBSD DragonFly SunOS Haiku MidnightBSD MINGW32_NT-6.1 MINGW64_NT-6.1 MINGW32_NT-10.0 MINGW64_NT-10.0))
 
 unlz4: lz4
 	ln -s lz4$(EXT) unlz4$(EXT)
diff --git a/programs/README.md b/programs/README.md
index 2ad0449..c1995af 100644
--- a/programs/README.md
+++ b/programs/README.md
@@ -1,18 +1,26 @@
 Command Line Interface for LZ4 library
 ============================================
 
-Command Line Interface (CLI) can be created using the `make` command without any additional parameters.
-There are also multiple targets that create different variations of CLI:
+### Build
+The Command Line Interface (CLI) can be generated
+using the `make` command without any additional parameters.
+
+The `Makefile` script supports all [standard conventions](https://www.gnu.org/prep/standards/html_node/Makefile-Conventions.html),
+including standard targets (`all`, `install`, `clean`, etc.)
+and standard variables (`CC`, `CFLAGS`, `CPPFLAGS`, etc.).
+
+For advanced use cases, there are targets to different variations of the CLI:
 - `lz4` : default CLI, with a command line syntax close to gzip
 - `lz4c` : Same as `lz4` with additional support legacy lz4 commands (incompatible with gzip)
 - `lz4c32` : Same as `lz4c`, but forced to compile in 32-bits mode
 
+The CLI generates and decodes [LZ4-compressed frames](../doc/lz4_Frame_format.md).
+
 
 #### Aggregation of parameters
 CLI supports aggregation of parameters i.e. `-b1`, `-e18`, and `-i1` can be joined into `-b1e18i1`.
 
 
-
 #### Benchmark in Command Line Interface
 CLI includes in-memory compression benchmark module for lz4.
 The benchmark is conducted using a given filename.
@@ -38,7 +46,9 @@ Arguments :
  -9     : High compression
  -d     : decompression (default for .lz4 extension)
  -z     : force compression
+ -D FILE: use FILE as dictionary
  -f     : overwrite output without prompting
+ -k     : preserve source files(s)  (default)
 --rm    : remove source file(s) after successful de/compression
  -h/-H  : display help/long help and exit
 
@@ -51,17 +61,20 @@ Advanced arguments :
  -m     : multiple input files (implies automatic output filenames)
  -r     : operate recursively on directories (sets also -m)
  -l     : compress using Legacy format (Linux kernel compression)
- -B#    : Block size [4-7] (default : 7)
+ -B#    : cut file into blocks of size # bytes [32+]
+                     or predefined block size [4-7] (default: 7)
  -BD    : Block dependency (improve compression ratio)
+ -BX    : enable block checksum (default:disabled)
 --no-frame-crc : disable stream checksum (default:enabled)
 --content-size : compressed frame includes original size (default:not present)
 --[no-]sparse  : sparse mode (default:enabled on file, disabled on stdout)
+--favor-decSpeed: compressed files decompress faster, but are less compressed
+--fast[=#]: switch to ultra fast compression level (default: 1)
+
 Benchmark arguments :
  -b#    : benchmark file(s), using # compression level (default : 1)
  -e#    : test all compression levels from -bX to # (default : 1)
- -i#    : minimum evaluation time in seconds (default : 3s)
- -B#    : cut file into independent blocks of size # bytes [32+]
-                      or predefined block size [4-7] (default: 7)
+ -i#    : minimum evaluation time in seconds (default : 3s)```
 ```
 
 #### License
diff --git a/programs/lz4.1 b/programs/lz4.1
index f35e29d..1576e45 100644
--- a/programs/lz4.1
+++ b/programs/lz4.1
@@ -1,5 +1,5 @@
 .
-.TH "LZ4" "1" "September 2018" "lz4 1.8.3" "User Commands"
+.TH "LZ4" "1" "April 2019" "lz4 1.9.0" "User Commands"
 .
 .SH "NAME"
 \fBlz4\fR \- lz4, unlz4, lz4cat \- Compress or decompress \.lz4 files
@@ -118,6 +118,14 @@ Benchmark mode, using \fB#\fR compression level\.
 Compression level, with # being any value from 1 to 12\. Higher values trade compression speed for compression ratio\. Values above 12 are considered the same as 12\. Recommended values are 1 for fast compression (default), and 9 for high compression\. Speed/compression trade\-off will vary depending on data to compress\. Decompression speed remains fast at all settings\.
 .
 .TP
+\fB\-\-fast[=#]\fR
+Switch to ultra\-fast compression levels\. The higher the value, the faster the compression speed, at the cost of some compression ratio\. If \fB=#\fR is not present, it defaults to \fB1\fR\. This setting overrides compression level if one was set previously\. Similarly, if a compression level is set after \fB\-\-fast\fR, it overrides it\.
+.
+.TP
+\fB\-\-favor\-decSpeed\fR
+Generate compressed data optimized for decompression speed\. Compressed data will be larger as a consequence (typically by ~0\.5%), while decompression speed will be improved by 5\-20%, depending on use cases\. This option only works in combination with very high compression levels (>=10)\.
+.
+.TP
 \fB\-D dictionaryName\fR
 Compress, decompress or benchmark using dictionary \fIdictionaryName\fR\. Compression and decompression must use the same dictionary to be compatible\. Using a different dictionary during decompression will either abort due to decompression error, or generate a checksum error\.
 .
@@ -151,12 +159,12 @@ Block size [4\-7](default : 7)
 \fB\-B4\fR= 64KB ; \fB\-B5\fR= 256KB ; \fB\-B6\fR= 1MB ; \fB\-B7\fR= 4MB
 .
 .TP
-\fB\-BD\fR
-Block Dependency (improves compression ratio on small blocks)
+\fB\-BI\fR
+Produce independent blocks (default)
 .
 .TP
-\fB\-\-fast[=#]\fR
-switch to ultra\-fast compression levels\. If \fB=#\fR is not present, it defaults to \fB1\fR\. The higher the value, the faster the compression speed, at the cost of some compression ratio\. This setting overwrites compression level if one was set previously\. Similarly, if a compression level is set after \fB\-\-fast\fR, it overrides it\.
+\fB\-BD\fR
+Blocks depend on predecessors (improves compression ratio, more noticeable on small blocks)
 .
 .TP
 \fB\-\-[no\-]frame\-crc\fR
diff --git a/programs/lz4.1.md b/programs/lz4.1.md
index 12b8e29..10449a0 100644
--- a/programs/lz4.1.md
+++ b/programs/lz4.1.md
@@ -126,12 +126,18 @@ only the latest one will be applied.
   Decompression speed remains fast at all settings.
 
 * `--fast[=#]`:
-  switch to ultra-fast compression levels.
+  Switch to ultra-fast compression levels.
   The higher the value, the faster the compression speed, at the cost of some compression ratio.
   If `=#` is not present, it defaults to `1`.
   This setting overrides compression level if one was set previously.
   Similarly, if a compression level is set after `--fast`, it overrides it.
 
+* `--favor-decSpeed`:
+  Generate compressed data optimized for decompression speed.
+  Compressed data will be larger as a consequence (typically by ~0.5%),
+  while decompression speed will be improved by 5-20%, depending on use cases.
+  This option only works in combination with very high compression levels (>=10).
+
 * `-D dictionaryName`:
   Compress, decompress or benchmark using dictionary _dictionaryName_.
   Compression and decompression must use the same dictionary to be compatible.
@@ -166,8 +172,11 @@ only the latest one will be applied.
   Block size \[4-7\](default : 7)<br/>
   `-B4`= 64KB ; `-B5`= 256KB ; `-B6`= 1MB ; `-B7`= 4MB
 
+* `-BI`:
+  Produce independent blocks (default)
+
 * `-BD`:
-  Block Dependency (improves compression ratio on small blocks)
+  Blocks depend on predecessors (improves compression ratio, more noticeable on small blocks)
 
 * `--[no-]frame-crc`:
   Select frame checksum (default:enabled)
diff --git a/programs/lz4cli.c b/programs/lz4cli.c
index 26a8089..8bd7042 100644
--- a/programs/lz4cli.c
+++ b/programs/lz4cli.c
@@ -92,7 +92,7 @@ static unsigned displayLevel = 2;   /* 0 : no display ; 1: errors only ; 2 : dow
 ***************************************/
 #define DEFAULT_COMPRESSOR   LZ4IO_compressFilename
 #define DEFAULT_DECOMPRESSOR LZ4IO_decompressFilename
-int LZ4IO_compressFilename_Legacy(const char* input_filename, const char* output_filename, int compressionlevel);   /* hidden function */
+int LZ4IO_compressFilename_Legacy(LZ4IO_prefs_t* const prefs, const char* input_filename, const char* output_filename, int compressionlevel);   /* hidden function */
 
 
 /*-***************************
@@ -134,20 +134,20 @@ static int usage_advanced(const char* exeName)
     DISPLAY( " -r     : operate recursively on directories (sets also -m) \n");
 #endif
     DISPLAY( " -l     : compress using Legacy format (Linux kernel compression)\n");
-    DISPLAY( " -B#    : Block size [4-7] (default : 7) \n");
-    DISPLAY( " -BD    : Block dependency (improve compression ratio) \n");
+    DISPLAY( " -B#    : cut file into blocks of size # bytes [32+] \n");
+    DISPLAY( "                     or predefined block size [4-7] (default: 7) \n");
+    DISPLAY( " -BI    : Block Independence (default) \n");
+    DISPLAY( " -BD    : Block dependency (improves compression ratio) \n");
     DISPLAY( " -BX    : enable block checksum (default:disabled) \n");
     DISPLAY( "--no-frame-crc : disable stream checksum (default:enabled) \n");
     DISPLAY( "--content-size : compressed frame includes original size (default:not present)\n");
     DISPLAY( "--[no-]sparse  : sparse mode (default:enabled on file, disabled on stdout)\n");
     DISPLAY( "--favor-decSpeed: compressed files decompress faster, but are less compressed \n");
-    DISPLAY( "--fast[=#]: switch to ultra fast compression level (default: %u)\n", 1);
+    DISPLAY( "--fast[=#]: switch to ultra fast compression level (default: %i)\n", 1);
     DISPLAY( "Benchmark arguments : \n");
     DISPLAY( " -b#    : benchmark file(s), using # compression level (default : 1) \n");
     DISPLAY( " -e#    : test all compression levels from -bX to # (default : 1)\n");
     DISPLAY( " -i#    : minimum evaluation time in seconds (default : 3s) \n");
-    DISPLAY( " -B#    : cut file into independent blocks of size # bytes [32+] \n");
-    DISPLAY( "                     or predefined block size [4-7] (default: 7) \n");
     if (g_lz4c_legacy_commands) {
         DISPLAY( "Legacy arguments : \n");
         DISPLAY( " -c0    : fast compression \n");
@@ -251,16 +251,16 @@ static int exeNameMatch(const char* exeName, const char* test)
 }
 
 /*! readU32FromChar() :
-    @return : unsigned integer value read from input in `char` format
-    allows and interprets K, KB, KiB, M, MB and MiB suffix.
-    Will also modify `*stringPtr`, advancing it to position where it stopped reading.
-    Note : function result can overflow if digit string > MAX_UINT */
+ * @return : unsigned integer value read from input in `char` format
+ *  allows and interprets K, KB, KiB, M, MB and MiB suffix.
+ *  Will also modify `*stringPtr`, advancing it to position where it stopped reading.
+ *  Note : function result can overflow if digit string > MAX_UINT */
 static unsigned readU32FromChar(const char** stringPtr)
 {
     unsigned result = 0;
     while ((**stringPtr >='0') && (**stringPtr <='9')) {
         result *= 10;
-        result += **stringPtr - '0';
+        result += (unsigned)(**stringPtr - '0');
         (*stringPtr)++ ;
     }
     if ((**stringPtr=='K') || (**stringPtr=='M')) {
@@ -278,7 +278,7 @@ static unsigned readU32FromChar(const char** stringPtr)
  *  If yes, @return 1 and advances *stringPtr to the position which immediately follows longCommand.
  * @return 0 and doesn't modify *stringPtr otherwise.
  */
-static unsigned longCommandWArg(const char** stringPtr, const char* longCommand)
+static int longCommandWArg(const char** stringPtr, const char* longCommand)
 {
     size_t const comSize = strlen(longCommand);
     int const result = !strncmp(*stringPtr, longCommand, comSize);
@@ -288,6 +288,19 @@ static unsigned longCommandWArg(const char** stringPtr, const char* longCommand)
 
 typedef enum { om_auto, om_compress, om_decompress, om_test, om_bench } operationMode_e;
 
+/** determineOpMode() :
+ *  auto-determine operation mode, based on input filename extension
+ *  @return `om_decompress` if input filename has .lz4 extension and `om_compress` otherwise.
+ */
+static operationMode_e determineOpMode(const char* inputFilename)
+{
+    size_t const inSize  = strlen(inputFilename);
+    size_t const extSize = strlen(LZ4_EXTENSION);
+    size_t const extStart= (inSize > extSize) ? inSize-extSize : 0;
+    if (!strcmp(inputFilename+extStart, LZ4_EXTENSION)) return om_decompress;
+    else return om_compress;
+}
+
 int main(int argc, const char** argv)
 {
     int i,
@@ -304,11 +317,12 @@ int main(int argc, const char** argv)
     const char* output_filename= NULL;
     const char* dictionary_filename = NULL;
     char* dynNameSpace = NULL;
-    const char** inFileNames = (const char**) calloc(argc, sizeof(char*));
+    const char** inFileNames = (const char**)calloc((size_t)argc, sizeof(char*));
     unsigned ifnIdx=0;
+    LZ4IO_prefs_t* const prefs = LZ4IO_defaultPreferences();
     const char nullOutput[] = NULL_OUTPUT;
     const char extension[] = LZ4_EXTENSION;
-    size_t blockSize = LZ4IO_setBlockSizeID(LZ4_BLOCKSIZEID_DEFAULT);
+    size_t blockSize = LZ4IO_setBlockSizeID(prefs, LZ4_BLOCKSIZEID_DEFAULT);
     const char* const exeName = lastNameFromPath(argv[0]);
 #ifdef UTIL_HAS_CREATEFILELIST
     const char** extendedFileList = NULL;
@@ -322,13 +336,14 @@ int main(int argc, const char** argv)
         return 1;
     }
     inFileNames[0] = stdinmark;
-    LZ4IO_setOverwrite(0);
+    LZ4IO_setOverwrite(prefs, 0);
 
     /* predefined behaviors, based on binary/link name */
     if (exeNameMatch(exeName, LZ4CAT)) {
         mode = om_decompress;
-        LZ4IO_setOverwrite(1);
-        LZ4IO_setRemoveSrcFile(0);
+        LZ4IO_setOverwrite(prefs, 1);
+        LZ4IO_setPassThrough(prefs, 1);
+        LZ4IO_setRemoveSrcFile(prefs, 0);
         forceStdout=1;
         output_filename=stdoutmark;
         displayLevel=1;
@@ -360,23 +375,23 @@ int main(int argc, const char** argv)
                     || (!strcmp(argument, "--uncompress"))) { mode = om_decompress; continue; }
                 if (!strcmp(argument,  "--multiple")) { multiple_inputs = 1; continue; }
                 if (!strcmp(argument,  "--test")) { mode = om_test; continue; }
-                if (!strcmp(argument,  "--force")) { LZ4IO_setOverwrite(1); continue; }
-                if (!strcmp(argument,  "--no-force")) { LZ4IO_setOverwrite(0); continue; }
+                if (!strcmp(argument,  "--force")) { LZ4IO_setOverwrite(prefs, 1); continue; }
+                if (!strcmp(argument,  "--no-force")) { LZ4IO_setOverwrite(prefs, 0); continue; }
                 if ((!strcmp(argument, "--stdout"))
                     || (!strcmp(argument, "--to-stdout"))) { forceStdout=1; output_filename=stdoutmark; continue; }
-                if (!strcmp(argument,  "--frame-crc")) { LZ4IO_setStreamChecksumMode(1); continue; }
-                if (!strcmp(argument,  "--no-frame-crc")) { LZ4IO_setStreamChecksumMode(0); continue; }
-                if (!strcmp(argument,  "--content-size")) { LZ4IO_setContentSize(1); continue; }
-                if (!strcmp(argument,  "--no-content-size")) { LZ4IO_setContentSize(0); continue; }
-                if (!strcmp(argument,  "--sparse")) { LZ4IO_setSparseFile(2); continue; }
-                if (!strcmp(argument,  "--no-sparse")) { LZ4IO_setSparseFile(0); continue; }
-                if (!strcmp(argument,  "--favor-decSpeed")) { LZ4IO_favorDecSpeed(1); continue; }
+                if (!strcmp(argument,  "--frame-crc")) { LZ4IO_setStreamChecksumMode(prefs, 1); continue; }
+                if (!strcmp(argument,  "--no-frame-crc")) { LZ4IO_setStreamChecksumMode(prefs, 0); continue; }
+                if (!strcmp(argument,  "--content-size")) { LZ4IO_setContentSize(prefs, 1); continue; }
+                if (!strcmp(argument,  "--no-content-size")) { LZ4IO_setContentSize(prefs, 0); continue; }
+                if (!strcmp(argument,  "--sparse")) { LZ4IO_setSparseFile(prefs, 2); continue; }
+                if (!strcmp(argument,  "--no-sparse")) { LZ4IO_setSparseFile(prefs, 0); continue; }
+                if (!strcmp(argument,  "--favor-decSpeed")) { LZ4IO_favorDecSpeed(prefs, 1); continue; }
                 if (!strcmp(argument,  "--verbose")) { displayLevel++; continue; }
                 if (!strcmp(argument,  "--quiet")) { if (displayLevel) displayLevel--; continue; }
                 if (!strcmp(argument,  "--version")) { DISPLAY(WELCOME_MESSAGE); return 0; }
                 if (!strcmp(argument,  "--help")) { usage_advanced(exeName); goto _cleanup; }
-                if (!strcmp(argument,  "--keep")) { LZ4IO_setRemoveSrcFile(0); continue; }   /* keep source file (default) */
-                if (!strcmp(argument,  "--rm")) { LZ4IO_setRemoveSrcFile(1); continue; }
+                if (!strcmp(argument,  "--keep")) { LZ4IO_setRemoveSrcFile(prefs, 0); continue; }   /* keep source file (default) */
+                if (!strcmp(argument,  "--rm")) { LZ4IO_setRemoveSrcFile(prefs, 1); continue; }
                 if (longCommandWArg(&argument, "--fast")) {
                         /* Parse optional acceleration factor */
                         if (*argument == '=') {
@@ -407,11 +422,11 @@ int main(int argc, const char** argv)
                     if (!strcmp(argument,  "c1")) { cLevel=9; argument++; continue; }  /* -c1 (high compression) */
                     if (!strcmp(argument,  "c2")) { cLevel=12; argument++; continue; } /* -c2 (very high compression) */
                     if (!strcmp(argument,  "hc")) { cLevel=12; argument++; continue; } /* -hc (very high compression) */
-                    if (!strcmp(argument,  "y"))  { LZ4IO_setOverwrite(1); continue; } /* -y (answer 'yes' to overwrite permission) */
+                    if (!strcmp(argument,  "y"))  { LZ4IO_setOverwrite(prefs, 1); continue; } /* -y (answer 'yes' to overwrite permission) */
                 }
 
                 if ((*argument>='0') && (*argument<='9')) {
-                    cLevel = readU32FromChar(&argument);
+                    cLevel = (int)readU32FromChar(&argument);
                     argument--;
                     continue;
                 }
@@ -426,7 +441,7 @@ int main(int argc, const char** argv)
 
                 case 'e':
                     argument++;
-                    cLevelLast = readU32FromChar(&argument);
+                    cLevelLast = (int)readU32FromChar(&argument);
                     argument--;
                     break;
 
@@ -456,13 +471,17 @@ int main(int argc, const char** argv)
                 case 'd': mode = om_decompress; break;
 
                     /* Force stdout, even if stdout==console */
-                case 'c': forceStdout=1; output_filename=stdoutmark; break;
+                case 'c':
+                  forceStdout=1;
+                  output_filename=stdoutmark;
+                  LZ4IO_setPassThrough(prefs, 1);
+                  break;
 
                     /* Test integrity */
                 case 't': mode = om_test; break;
 
                     /* Overwrite */
-                case 'f': LZ4IO_setOverwrite(1); break;
+                case 'f': LZ4IO_setOverwrite(prefs, 1); break;
 
                     /* Verbose mode */
                 case 'v': displayLevel++; break;
@@ -471,7 +490,7 @@ int main(int argc, const char** argv)
                 case 'q': if (displayLevel) displayLevel--; break;
 
                     /* keep source file (default anyway, so useless) (for xz/lzma compatibility) */
-                case 'k': LZ4IO_setRemoveSrcFile(0); break;
+                case 'k': LZ4IO_setRemoveSrcFile(prefs, 0); break;
 
                     /* Modify Block Properties */
                 case 'B':
@@ -479,8 +498,9 @@ int main(int argc, const char** argv)
                         int exitBlockProperties=0;
                         switch(argument[1])
                         {
-                        case 'D': LZ4IO_setBlockMode(LZ4IO_blockLinked); argument++; break;
-                        case 'X': LZ4IO_setBlockChecksumMode(1); argument ++; break;   /* disabled by default */
+                        case 'D': LZ4IO_setBlockMode(prefs, LZ4IO_blockLinked); argument++; break;
+                        case 'I': LZ4IO_setBlockMode(prefs, LZ4IO_blockIndependent); argument++; break;
+                        case 'X': LZ4IO_setBlockChecksumMode(prefs, 1); argument ++; break;   /* disabled by default */
                         default :
                             if (argument[1] < '0' || argument[1] > '9') {
                                 exitBlockProperties=1;
@@ -492,16 +512,17 @@ int main(int argc, const char** argv)
                                 argument--;
                                 if (B < 4) badusage(exeName);
                                 if (B <= 7) {
-                                    blockSize = LZ4IO_setBlockSizeID(B);
+                                    blockSize = LZ4IO_setBlockSizeID(prefs, B);
                                     BMK_setBlockSize(blockSize);
                                     DISPLAYLEVEL(2, "using blocks of size %u KB \n", (U32)(blockSize>>10));
                                 } else {
                                     if (B < 32) badusage(exeName);
-                                    BMK_setBlockSize(B);
-                                    if (B >= 1024) {
-                                        DISPLAYLEVEL(2, "bench: using blocks of size %u KB \n", (U32)(B>>10));
+                                    blockSize = LZ4IO_setBlockSize(prefs, B);
+                                    BMK_setBlockSize(blockSize);
+                                    if (blockSize >= 1024) {
+                                        DISPLAYLEVEL(2, "using blocks of size %u KB \n", (U32)(blockSize>>10));
                                     } else {
-                                        DISPLAYLEVEL(2, "bench: using blocks of size %u bytes \n", (U32)(B));
+                                        DISPLAYLEVEL(2, "using blocks of size %u bytes \n", (U32)(blockSize));
                                     }
                                 }
                                 break;
@@ -605,7 +626,7 @@ int main(int argc, const char** argv)
     }
 
     if (mode == om_test) {
-        LZ4IO_setTestMode(1);
+        LZ4IO_setTestMode(prefs, 1);
         output_filename = nulmark;
         mode = om_decompress;   /* defer to decompress */
     }
@@ -615,7 +636,7 @@ int main(int argc, const char** argv)
             DISPLAYLEVEL(1, "refusing to read from a console\n");
             exit(1);
         }
-        LZ4IO_setDictionaryFilename(dictionary_filename);
+        LZ4IO_setDictionaryFilename(prefs, dictionary_filename);
     }
 
     /* compress or decompress */
@@ -633,11 +654,7 @@ int main(int argc, const char** argv)
     while ((!output_filename) && (multiple_inputs==0)) {
         if (!IS_CONSOLE(stdout)) { output_filename=stdoutmark; break; }   /* Default to stdout whenever possible (i.e. not a console) */
         if (mode == om_auto) {  /* auto-determine compression or decompression, based on file extension */
-            size_t const inSize  = strlen(input_filename);
-            size_t const extSize = strlen(LZ4_EXTENSION);
-            size_t const extStart= (inSize > extSize) ? inSize-extSize : 0;
-            if (!strcmp(input_filename+extStart, LZ4_EXTENSION)) mode = om_decompress;
-            else mode = om_compress;
+            mode = determineOpMode(input_filename);
         }
         if (mode == om_compress) {   /* compression to file */
             size_t const l = strlen(input_filename);
@@ -675,23 +692,28 @@ int main(int argc, const char** argv)
     if (!strcmp(output_filename,stdoutmark) && (displayLevel==2)) displayLevel=1;
     if ((multiple_inputs) && (displayLevel==2)) displayLevel=1;
 
+    /* Auto-determine compression or decompression, based on file extension */
+    if (mode == om_auto) {
+        mode = determineOpMode(input_filename);
+    }
+
     /* IO Stream/File */
-    LZ4IO_setNotificationLevel(displayLevel);
+    LZ4IO_setNotificationLevel((int)displayLevel);
     if (ifnIdx == 0) multiple_inputs = 0;
     if (mode == om_decompress) {
         if (multiple_inputs)
-            operationResult = LZ4IO_decompressMultipleFilenames(inFileNames, ifnIdx, !strcmp(output_filename,stdoutmark) ? stdoutmark : LZ4_EXTENSION);
+            operationResult = LZ4IO_decompressMultipleFilenames(prefs, inFileNames, ifnIdx, !strcmp(output_filename,stdoutmark) ? stdoutmark : LZ4_EXTENSION);
         else
-            operationResult = DEFAULT_DECOMPRESSOR(input_filename, output_filename);
+            operationResult = DEFAULT_DECOMPRESSOR(prefs, input_filename, output_filename);
     } else {   /* compression is default action */
         if (legacy_format) {
             DISPLAYLEVEL(3, "! Generating LZ4 Legacy format (deprecated) ! \n");
-            LZ4IO_compressFilename_Legacy(input_filename, output_filename, cLevel);
+            LZ4IO_compressFilename_Legacy(prefs, input_filename, output_filename, cLevel);
         } else {
             if (multiple_inputs)
-                operationResult = LZ4IO_compressMultipleFilenames(inFileNames, ifnIdx, LZ4_EXTENSION, cLevel);
+                operationResult = LZ4IO_compressMultipleFilenames(prefs, inFileNames, ifnIdx, !strcmp(output_filename,stdoutmark) ? stdoutmark : LZ4_EXTENSION, cLevel);
             else
-                operationResult = DEFAULT_COMPRESSOR(input_filename, output_filename, cLevel);
+                operationResult = DEFAULT_COMPRESSOR(prefs, input_filename, output_filename, cLevel);
         }
     }
 
@@ -704,6 +726,7 @@ _cleanup:
         inFileNames = NULL;
     }
 #endif
+    LZ4IO_freePreferences(prefs);
     free((void*)inFileNames);
     return operationResult;
 }
diff --git a/programs/lz4io.c b/programs/lz4io.c
index 28d6537..121bd44 100644
--- a/programs/lz4io.c
+++ b/programs/lz4io.c
@@ -107,18 +107,23 @@ static clock_t g_time = 0;
 /**************************************
 *  Local Parameters
 **************************************/
-static int g_overwrite = 1;
-static int g_testMode = 0;
-static int g_blockSizeId = LZ4IO_BLOCKSIZEID_DEFAULT;
-static int g_blockChecksum = 0;
-static int g_streamChecksum = 1;
-static int g_blockIndependence = 1;
-static int g_sparseFileSupport = 1;
-static int g_contentSizeFlag = 0;
-static int g_useDictionary = 0;
-static unsigned g_favorDecSpeed = 0;
-static const char* g_dictionaryFilename = NULL;
 
+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;
+};
 
 /**************************************
 *  Exceptions
@@ -150,55 +155,109 @@ static const char* g_dictionaryFilename = NULL;
 /* ****************** Parameters ******************** */
 /* ************************************************** */
 
-int LZ4IO_setDictionaryFilename(const char* dictionaryFilename) {
-    g_dictionaryFilename = dictionaryFilename;
-    g_useDictionary = dictionaryFilename != NULL;
-    return g_useDictionary;
+LZ4IO_prefs_t* LZ4IO_defaultPreferences(void)
+{
+  LZ4IO_prefs_t* const ret = (LZ4IO_prefs_t*)malloc(sizeof(LZ4IO_prefs_t));
+  if (!ret) EXM_THROW(21, "Allocation error : not enough memory");
+  ret->passThrough = 0;
+  ret->overwrite = 1;
+  ret->testMode = 0;
+  ret->blockSizeId = LZ4IO_BLOCKSIZEID_DEFAULT;
+  ret->blockSize = 0;
+  ret->blockChecksum = 0;
+  ret->streamChecksum = 1;
+  ret->blockIndependence = 1;
+  ret->sparseFileSupport = 1;
+  ret->contentSizeFlag = 0;
+  ret->useDictionary = 0;
+  ret->favorDecSpeed = 0;
+  ret->dictionaryFilename = NULL;
+  ret->removeSrcFile = 0;
+  return ret;
+}
+
+void LZ4IO_freePreferences(LZ4IO_prefs_t* const prefs)
+{
+  free(prefs);
+}
+
+
+int LZ4IO_setDictionaryFilename(LZ4IO_prefs_t* const prefs, const char* dictionaryFilename)
+{
+    prefs->dictionaryFilename = dictionaryFilename;
+    prefs->useDictionary = dictionaryFilename != NULL;
+    return prefs->useDictionary;
+}
+
+/* Default setting : passThrough = 0; return : passThrough mode (0/1) */
+int LZ4IO_setPassThrough(LZ4IO_prefs_t* const prefs, int yes)
+{
+   prefs->passThrough = (yes!=0);
+   return prefs->passThrough;
 }
 
+
 /* Default setting : overwrite = 1; return : overwrite mode (0/1) */
-int LZ4IO_setOverwrite(int yes)
+int LZ4IO_setOverwrite(LZ4IO_prefs_t* const prefs, int yes)
 {
-   g_overwrite = (yes!=0);
-   return g_overwrite;
+   prefs->overwrite = (yes!=0);
+   return prefs->overwrite;
 }
 
 /* Default setting : testMode = 0; return : testMode (0/1) */
-int LZ4IO_setTestMode(int yes)
+int LZ4IO_setTestMode(LZ4IO_prefs_t* const prefs, int yes)
 {
-   g_testMode = (yes!=0);
-   return g_testMode;
+   prefs->testMode = (yes!=0);
+   return prefs->testMode;
 }
 
 /* blockSizeID : valid values : 4-5-6-7 */
-size_t LZ4IO_setBlockSizeID(unsigned bsid)
+size_t LZ4IO_setBlockSizeID(LZ4IO_prefs_t* const prefs, unsigned bsid)
 {
     static const size_t blockSizeTable[] = { 64 KB, 256 KB, 1 MB, 4 MB };
     static const unsigned minBlockSizeID = 4;
     static const unsigned maxBlockSizeID = 7;
     if ((bsid < minBlockSizeID) || (bsid > maxBlockSizeID)) return 0;
-    g_blockSizeId = bsid;
-    return blockSizeTable[g_blockSizeId-minBlockSizeID];
+    prefs->blockSizeId = bsid;
+    prefs->blockSize = blockSizeTable[prefs->blockSizeId-minBlockSizeID];
+    return prefs->blockSize;
 }
 
-int LZ4IO_setBlockMode(LZ4IO_blockMode_t blockMode)
+size_t LZ4IO_setBlockSize(LZ4IO_prefs_t* const prefs, size_t blockSize)
 {
-    g_blockIndependence = (blockMode == LZ4IO_blockIndependent);
-    return g_blockIndependence;
+    static const size_t minBlockSize = 32;
+    static const size_t maxBlockSize = 4 MB;
+    unsigned bsid = 0;
+    if (blockSize < minBlockSize) blockSize = minBlockSize;
+    if (blockSize > maxBlockSize) blockSize = maxBlockSize;
+    prefs->blockSize = blockSize;
+    blockSize--;
+    /* find which of { 64k, 256k, 1MB, 4MB } is closest to blockSize */
+    while (blockSize >>= 2)
+        bsid++;
+    if (bsid < 7) bsid = 7;
+    prefs->blockSizeId = bsid-3;
+    return prefs->blockSize;
+}
+
+int LZ4IO_setBlockMode(LZ4IO_prefs_t* const prefs, LZ4IO_blockMode_t blockMode)
+{
+    prefs->blockIndependence = (blockMode == LZ4IO_blockIndependent);
+    return prefs->blockIndependence;
 }
 
 /* Default setting : no block checksum */
-int LZ4IO_setBlockChecksumMode(int enable)
+int LZ4IO_setBlockChecksumMode(LZ4IO_prefs_t* const prefs, int enable)
 {
-    g_blockChecksum = (enable != 0);
-    return g_blockChecksum;
+    prefs->blockChecksum = (enable != 0);
+    return prefs->blockChecksum;
 }
 
 /* Default setting : checksum enabled */
-int LZ4IO_setStreamChecksumMode(int enable)
+int LZ4IO_setStreamChecksumMode(LZ4IO_prefs_t* const prefs, int enable)
 {
-    g_streamChecksum = (enable != 0);
-    return g_streamChecksum;
+    prefs->streamChecksum = (enable != 0);
+    return prefs->streamChecksum;
 }
 
 /* Default setting : 0 (no notification) */
@@ -209,27 +268,29 @@ int LZ4IO_setNotificationLevel(int level)
 }
 
 /* Default setting : 0 (disabled) */
-int LZ4IO_setSparseFile(int enable)
+int LZ4IO_setSparseFile(LZ4IO_prefs_t* const prefs, int enable)
 {
-    g_sparseFileSupport = (enable!=0);
-    return g_sparseFileSupport;
+    prefs->sparseFileSupport = (enable!=0);
+    return prefs->sparseFileSupport;
 }
 
 /* Default setting : 0 (disabled) */
-int LZ4IO_setContentSize(int enable)
+int LZ4IO_setContentSize(LZ4IO_prefs_t* const prefs, int enable)
 {
-    g_contentSizeFlag = (enable!=0);
-    return g_contentSizeFlag;
+    prefs->contentSizeFlag = (enable!=0);
+    return prefs->contentSizeFlag;
 }
 
 /* Default setting : 0 (disabled) */
-void LZ4IO_favorDecSpeed(int favor)
+void LZ4IO_favorDecSpeed(LZ4IO_prefs_t* const prefs, int favor)
 {
-    g_favorDecSpeed = (favor!=0);
+    prefs->favorDecSpeed = (favor!=0);
 }
 
-static U32 g_removeSrcFile = 0;
-void LZ4IO_setRemoveSrcFile(unsigned flag) { g_removeSrcFile = (flag>0); }
+void LZ4IO_setRemoveSrcFile(LZ4IO_prefs_t* const prefs, unsigned flag)
+{
+  prefs->removeSrcFile = (flag>0);
+}
 
 
 
@@ -237,7 +298,6 @@ void LZ4IO_setRemoveSrcFile(unsigned flag) { g_removeSrcFile = (flag>0); }
 ** ********************** LZ4 File / Pipe compression ********************* **
 ** ************************************************************************ */
 
-static int LZ4IO_GetBlockSize_FromBlockId (int id) { return (1 << (8 + (2 * id))); }
 static int LZ4IO_isSkippableMagicNumber(unsigned int magic) {
     return (magic & LZ4IO_SKIPPABLEMASK) == LZ4IO_SKIPPABLE0;
 }
@@ -263,22 +323,23 @@ static FILE* LZ4IO_openSrcFile(const char* srcFileName)
 }
 
 /** FIO_openDstFile() :
- * condition : `dstFileName` must be non-NULL.
+ *  condition : `dstFileName` must be non-NULL.
  * @result : FILE* to `dstFileName`, or NULL if it fails */
-static FILE* LZ4IO_openDstFile(const char* dstFileName)
+static FILE* LZ4IO_openDstFile(LZ4IO_prefs_t* const prefs, const char* dstFileName)
 {
     FILE* f;
+    assert(dstFileName != NULL);
 
     if (!strcmp (dstFileName, stdoutmark)) {
         DISPLAYLEVEL(4,"Using stdout for output\n");
         f = stdout;
         SET_BINARY_MODE(stdout);
-        if (g_sparseFileSupport==1) {
-            g_sparseFileSupport = 0;
+        if (prefs->sparseFileSupport==1) {
+            prefs->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 */
+        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);
@@ -299,7 +360,7 @@ static FILE* LZ4IO_openDstFile(const char* dstFileName)
     }
 
     /* sparse file */
-    if (f && g_sparseFileSupport) { SET_SPARSE_FILE_MODE(f); }
+    if (f && prefs->sparseFileSupport) { SET_SPARSE_FILE_MODE(f); }
 
     return f;
 }
@@ -329,44 +390,50 @@ 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(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)
 {
-    int (*compressionFunction)(const char* src, char* dst, int srcSize, int dstSize, int cLevel);
+    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;
     unsigned long long filesize = 0;
     unsigned long long compressedfilesize = MAGICNUMBER_SIZE;
     char* in_buff;
     char* out_buff;
     const int outBuffSize = LZ4_compressBound(LEGACY_BLOCKSIZE);
-    FILE* finput;
+    FILE* const finput = LZ4IO_openSrcFile(input_filename);
     FILE* foutput;
     clock_t clockEnd;
 
     /* Init */
     clock_t const clockStart = clock();
-    compressionFunction = (compressionlevel < 3) ? LZ4IO_LZ4_compress : LZ4_compress_HC;
+    if (finput == NULL)
+        EXM_THROW(20, "%s : open file error ", input_filename);
 
-    finput = LZ4IO_openSrcFile(input_filename);
-    if (finput == NULL) EXM_THROW(20, "%s : open file error ", input_filename);
-    foutput = LZ4IO_openDstFile(output_filename);
-    if (foutput == NULL) { fclose(finput); EXM_THROW(20, "%s : open file error ", input_filename); }
+    foutput = LZ4IO_openDstFile(prefs, output_filename);
+    if (foutput == NULL) {
+        fclose(finput);
+        EXM_THROW(20, "%s : open file error ", input_filename);
+    }
 
     /* Allocate Memory */
     in_buff = (char*)malloc(LEGACY_BLOCKSIZE);
-    out_buff = (char*)malloc(outBuffSize);
-    if (!in_buff || !out_buff) EXM_THROW(21, "Allocation error : not enough memory");
+    out_buff = (char*)malloc(outBuffSize + 4);
+    if (!in_buff || !out_buff)
+        EXM_THROW(21, "Allocation error : not enough memory");
 
     /* Write Archive Header */
     LZ4IO_writeLE32(out_buff, LEGACY_MAGICNUMBER);
-    { size_t const sizeCheck = fwrite(out_buff, 1, MAGICNUMBER_SIZE, foutput);
-      if (sizeCheck != MAGICNUMBER_SIZE) EXM_THROW(22, "Write error : cannot write header"); }
+    {   size_t const writeSize = fwrite(out_buff, 1, MAGICNUMBER_SIZE, foutput);
+        if (writeSize != MAGICNUMBER_SIZE)
+            EXM_THROW(22, "Write error : cannot write header");
+    }
 
     /* Main Loop */
     while (1) {
-        unsigned int outSize;
+        int outSize;
         /* Read Block */
-        size_t const inSize = (int) fread(in_buff, (size_t)1, (size_t)LEGACY_BLOCKSIZE, finput);
+        size_t const inSize = fread(in_buff, (size_t)1, (size_t)LEGACY_BLOCKSIZE, finput);
+        assert(inSize <= LEGACY_BLOCKSIZE);
         if (inSize == 0) break;
-        if (inSize > LEGACY_BLOCKSIZE) EXM_THROW(23, "Read error : wrong fread() size report ");   /* should be impossible */
         filesize += inSize;
 
         /* Compress Block */
@@ -376,9 +443,11 @@ int LZ4IO_compressFilename_Legacy(const char* input_filename, const char* output
                 (int)(filesize>>20), (double)compressedfilesize/filesize*100);
 
         /* Write Block */
-        LZ4IO_writeLE32(out_buff, outSize);
-        {   size_t const sizeCheck = fwrite(out_buff, 1, outSize+4, foutput);
-            if (sizeCheck!=(size_t)(outSize+4))
+        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 (ferror(finput)) EXM_THROW(25, "Error while reading %s ", input_filename);
@@ -418,7 +487,7 @@ typedef struct {
     LZ4F_CDict* cdict;
 } cRess_t;
 
-static void* LZ4IO_createDict(const char* dictFilename, size_t *dictSize) {
+static void* LZ4IO_createDict(LZ4IO_prefs_t* const prefs, size_t *dictSize) {
     size_t readSize;
     size_t dictEnd = 0;
     size_t dictLen = 0;
@@ -426,6 +495,7 @@ static void* LZ4IO_createDict(const char* dictFilename, size_t *dictSize) {
     size_t circularBufSize = LZ4_MAX_DICT_SIZE;
     char* circularBuf;
     char* dictBuf;
+    const char* dictFilename = prefs->dictionaryFilename;
     FILE* dictFile;
 
     if (!dictFilename) EXM_THROW(25, "Dictionary error : no filename provided");
@@ -475,23 +545,23 @@ static void* LZ4IO_createDict(const char* dictFilename, size_t *dictSize) {
     return dictBuf;
 }
 
-static LZ4F_CDict* LZ4IO_createCDict(void) {
+static LZ4F_CDict* LZ4IO_createCDict(LZ4IO_prefs_t* const prefs) {
     size_t dictionarySize;
     void* dictionaryBuffer;
     LZ4F_CDict* cdict;
-    if (!g_useDictionary) {
+    if (!prefs->useDictionary) {
         return NULL;
     }
-    dictionaryBuffer = LZ4IO_createDict(g_dictionaryFilename, &dictionarySize);
+    dictionaryBuffer = LZ4IO_createDict(prefs, &dictionarySize);
     if (!dictionaryBuffer) EXM_THROW(25, "Dictionary error : could not create dictionary");
     cdict = LZ4F_createCDict(dictionaryBuffer, dictionarySize);
     free(dictionaryBuffer);
     return cdict;
 }
 
-static cRess_t LZ4IO_createCResources(void)
+static cRess_t LZ4IO_createCResources(LZ4IO_prefs_t* const prefs)
 {
-    const size_t blockSize = (size_t)LZ4IO_GetBlockSize_FromBlockId (g_blockSizeId);
+    const size_t blockSize = prefs->blockSize;
     cRess_t ress;
 
     LZ4F_errorCode_t const errorCode = LZ4F_createCompressionContext(&(ress.ctx), LZ4F_VERSION);
@@ -504,7 +574,7 @@ static cRess_t LZ4IO_createCResources(void)
     ress.dstBuffer = malloc(ress.dstBufferSize);
     if (!ress.srcBuffer || !ress.dstBuffer) EXM_THROW(31, "Allocation error : not enough memory");
 
-    ress.cdict = LZ4IO_createCDict();
+    ress.cdict = LZ4IO_createCDict(prefs);
 
     return ress;
 }
@@ -526,7 +596,10 @@ static void LZ4IO_freeCResources(cRess_t ress)
  * result : 0 : compression completed correctly
  *          1 : missing or pb opening srcFileName
  */
-static int LZ4IO_compressFilename_extRess(cRess_t ress, const char* srcFileName, const char* dstFileName, int compressionLevel)
+static int
+LZ4IO_compressFilename_extRess(LZ4IO_prefs_t* const io_prefs, cRess_t ress,
+                               const char* srcFileName, const char* dstFileName,
+                               int compressionLevel)
 {
     unsigned long long filesize = 0;
     unsigned long long compressedfilesize = 0;
@@ -535,7 +608,7 @@ static int LZ4IO_compressFilename_extRess(cRess_t ress, const char* srcFileName,
     void* const srcBuffer = ress.srcBuffer;
     void* const dstBuffer = ress.dstBuffer;
     const size_t dstBufferSize = ress.dstBufferSize;
-    const size_t blockSize = (size_t)LZ4IO_GetBlockSize_FromBlockId (g_blockSizeId);
+    const size_t blockSize = io_prefs->blockSize;
     size_t readSize;
     LZ4F_compressionContext_t ctx = ress.ctx;   /* just a pointer */
     LZ4F_preferences_t prefs;
@@ -543,7 +616,7 @@ static int LZ4IO_compressFilename_extRess(cRess_t ress, const char* srcFileName,
     /* Init */
     srcFile = LZ4IO_openSrcFile(srcFileName);
     if (srcFile == NULL) return 1;
-    dstFile = LZ4IO_openDstFile(dstFileName);
+    dstFile = LZ4IO_openDstFile(io_prefs, dstFileName);
     if (dstFile == NULL) { fclose(srcFile); return 1; }
     memset(&prefs, 0, sizeof(prefs));
 
@@ -551,12 +624,12 @@ static int LZ4IO_compressFilename_extRess(cRess_t ress, const char* srcFileName,
     /* Set compression parameters */
     prefs.autoFlush = 1;
     prefs.compressionLevel = compressionLevel;
-    prefs.frameInfo.blockMode = (LZ4F_blockMode_t)g_blockIndependence;
-    prefs.frameInfo.blockSizeID = (LZ4F_blockSizeID_t)g_blockSizeId;
-    prefs.frameInfo.blockChecksumFlag = (LZ4F_blockChecksum_t)g_blockChecksum;
-    prefs.frameInfo.contentChecksumFlag = (LZ4F_contentChecksum_t)g_streamChecksum;
-    prefs.favorDecSpeed = g_favorDecSpeed;
-    if (g_contentSizeFlag) {
+    prefs.frameInfo.blockMode = (LZ4F_blockMode_t)io_prefs->blockIndependence;
+    prefs.frameInfo.blockSizeID = (LZ4F_blockSizeID_t)io_prefs->blockSizeId;
+    prefs.frameInfo.blockChecksumFlag = (LZ4F_blockChecksum_t)io_prefs->blockChecksum;
+    prefs.frameInfo.contentChecksumFlag = (LZ4F_contentChecksum_t)io_prefs->streamChecksum;
+    prefs.favorDecSpeed = io_prefs->favorDecSpeed;
+    if (io_prefs->contentSizeFlag) {
       U64 const fileSize = UTIL_getFileSize(srcFileName);
       prefs.frameInfo.contentSize = fileSize;   /* == 0 if input == stdin */
       if (fileSize==0)
@@ -622,9 +695,9 @@ static int LZ4IO_compressFilename_extRess(cRess_t ress, const char* srcFileName,
         compressedfilesize += headerSize;
     }
 
-    /* Release files */
+    /* Release file handlers */
     fclose (srcFile);
-    fclose (dstFile);
+    if (strcmp(dstFileName,stdoutmark)) fclose (dstFile);   /* do not close stdout */
 
     /* Copy owner, file permissions and modification time */
     {   stat_t statbuf;
@@ -635,7 +708,7 @@ static int LZ4IO_compressFilename_extRess(cRess_t ress, const char* srcFileName,
             UTIL_setFileStat(dstFileName, &statbuf);
     }   }
 
-    if (g_removeSrcFile) {  /* remove source file : --rm */
+    if (io_prefs->removeSrcFile) {  /* remove source file : --rm */
         if (remove(srcFileName))
             EXM_THROW(40, "Remove error : %s: %s", srcFileName, strerror(errno));
     }
@@ -650,13 +723,13 @@ static int LZ4IO_compressFilename_extRess(cRess_t ress, const char* srcFileName,
 }
 
 
-int LZ4IO_compressFilename(const char* srcFileName, const char* dstFileName, int compressionLevel)
+int LZ4IO_compressFilename(LZ4IO_prefs_t* const prefs, const char* srcFileName, const char* dstFileName, int compressionLevel)
 {
     UTIL_time_t const timeStart = UTIL_getTime();
     clock_t const cpuStart = clock();
-    cRess_t const ress = LZ4IO_createCResources();
+    cRess_t const ress = LZ4IO_createCResources(prefs);
 
-    int const result = LZ4IO_compressFilename_extRess(ress, srcFileName, dstFileName, compressionLevel);
+    int const result = LZ4IO_compressFilename_extRess(prefs, ress, srcFileName, dstFileName, compressionLevel);
 
     /* Free resources */
     LZ4IO_freeCResources(ress);
@@ -675,7 +748,10 @@ int LZ4IO_compressFilename(const char* srcFileName, const char* dstFileName, int
 
 
 #define FNSPACE 30
-int LZ4IO_compressMultipleFilenames(const char** inFileNamesTable, int ifntSize, const char* suffix, int compressionLevel)
+int LZ4IO_compressMultipleFilenames(LZ4IO_prefs_t* const prefs,
+                              const char** inFileNamesTable, int ifntSize,
+                              const char* suffix,
+                              int compressionLevel)
 {
     int i;
     int missed_files = 0;
@@ -685,16 +761,31 @@ int LZ4IO_compressMultipleFilenames(const char** inFileNamesTable, int ifntSize,
     cRess_t ress;
 
     if (dstFileName == NULL) return ifntSize;   /* not enough memory */
-    ress = LZ4IO_createCResources();
+    ress = LZ4IO_createCResources(prefs);
 
     /* loop on each file */
     for (i=0; i<ifntSize; i++) {
         size_t const ifnSize = strlen(inFileNamesTable[i]);
-        if (ofnSize <= ifnSize+suffixSize+1) { free(dstFileName); ofnSize = ifnSize + 20; dstFileName = (char*)malloc(ofnSize); if (dstFileName==NULL) { LZ4IO_freeCResources(ress); return ifntSize; } }
+        if (!strcmp(suffix, stdoutmark)) {
+            missed_files += LZ4IO_compressFilename_extRess(prefs, ress,
+                                    inFileNamesTable[i], stdoutmark,
+                                    compressionLevel);
+            continue;
+        }
+        if (ofnSize <= ifnSize+suffixSize+1) {
+            free(dstFileName);
+            ofnSize = ifnSize + 20;
+            dstFileName = (char*)malloc(ofnSize);
+            if (dstFileName==NULL) {
+                LZ4IO_freeCResources(ress);
+                return ifntSize;
+        }   }
         strcpy(dstFileName, inFileNamesTable[i]);
         strcat(dstFileName, suffix);
 
-        missed_files += LZ4IO_compressFilename_extRess(ress, inFileNamesTable[i], dstFileName, compressionLevel);
+        missed_files += LZ4IO_compressFilename_extRess(prefs, ress,
+                                inFileNamesTable[i], dstFileName,
+                                compressionLevel);
     }
 
     /* Close & Free */
@@ -709,18 +800,19 @@ int LZ4IO_compressMultipleFilenames(const char** inFileNamesTable, int ifntSize,
 /* ********************** LZ4 file-stream Decompression **************** */
 /* ********************************************************************* */
 
+/* It's presumed that s points to a memory space of size >= 4 */
 static unsigned LZ4IO_readLE32 (const void* s)
 {
     const unsigned char* const srcPtr = (const unsigned char*)s;
     unsigned value32 = srcPtr[0];
-    value32 += (srcPtr[1]<<8);
-    value32 += (srcPtr[2]<<16);
-    value32 += ((unsigned)srcPtr[3])<<24;
+    value32 += (unsigned)srcPtr[1] <<  8;
+    value32 += (unsigned)srcPtr[2] << 16;
+    value32 += (unsigned)srcPtr[3] << 24;
     return value32;
 }
 
 
-static unsigned LZ4IO_fwriteSparse(FILE* file, const void* buffer, size_t bufferSize, unsigned storedSkips)
+static unsigned LZ4IO_fwriteSparse(LZ4IO_prefs_t* const prefs, FILE* file, const void* buffer, size_t bufferSize, unsigned storedSkips)
 {
     const size_t sizeT = sizeof(size_t);
     const size_t maskT = sizeT -1 ;
@@ -730,7 +822,7 @@ static unsigned LZ4IO_fwriteSparse(FILE* file, const void* buffer, size_t buffer
     const size_t* const bufferTEnd = bufferT + bufferSizeT;
     const size_t segmentSizeT = (32 KB) / sizeT;
 
-    if (!g_sparseFileSupport) {  /* normal write */
+    if (!prefs->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;
@@ -799,7 +891,7 @@ static void LZ4IO_fwriteSparseEnd(FILE* file, unsigned storedSkips)
 
 
 static unsigned g_magicRead = 0;   /* out-parameter of LZ4IO_decodeLegacyStream() */
-static unsigned long long LZ4IO_decodeLegacyStream(FILE* finput, FILE* foutput)
+static unsigned long long LZ4IO_decodeLegacyStream(LZ4IO_prefs_t* const prefs, FILE* finput, FILE* foutput)
 {
     unsigned long long streamSize = 0;
     unsigned storedSkips = 0;
@@ -833,7 +925,7 @@ static unsigned long long LZ4IO_decodeLegacyStream(FILE* finput, FILE* foutput)
             if (decodeSize < 0) EXM_THROW(53, "Decoding Failed ! Corrupted input detected !");
             streamSize += decodeSize;
             /* Write Block */
-            storedSkips = LZ4IO_fwriteSparse(foutput, out_buff, decodeSize, storedSkips); /* success or die */
+            storedSkips = LZ4IO_fwriteSparse(prefs, foutput, out_buff, decodeSize, storedSkips); /* success or die */
     }   }
     if (ferror(finput)) EXM_THROW(54, "Read error : ferror");
 
@@ -859,19 +951,19 @@ typedef struct {
     size_t dictBufferSize;
 } dRess_t;
 
-static void LZ4IO_loadDDict(dRess_t* ress) {
-    if (!g_useDictionary) {
+static void LZ4IO_loadDDict(LZ4IO_prefs_t* const prefs, dRess_t* ress) {
+    if (!prefs->useDictionary) {
         ress->dictBuffer = NULL;
         ress->dictBufferSize = 0;
         return;
     }
 
-    ress->dictBuffer = LZ4IO_createDict(g_dictionaryFilename, &ress->dictBufferSize);
+    ress->dictBuffer = LZ4IO_createDict(prefs, &ress->dictBufferSize);
     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(void)
+static dRess_t LZ4IO_createDResources(LZ4IO_prefs_t* const prefs)
 {
     dRess_t ress;
 
@@ -886,7 +978,7 @@ static dRess_t LZ4IO_createDResources(void)
     ress.dstBuffer = malloc(ress.dstBufferSize);
     if (!ress.srcBuffer || !ress.dstBuffer) EXM_THROW(61, "Allocation error : not enough memory");
 
-    LZ4IO_loadDDict(&ress);
+    LZ4IO_loadDDict(prefs, &ress);
 
     ress.dstFile = NULL;
     return ress;
@@ -902,7 +994,7 @@ static void LZ4IO_freeDResources(dRess_t ress)
 }
 
 
-static unsigned long long LZ4IO_decompressLZ4F(dRess_t ress, FILE* srcFile, FILE* dstFile)
+static unsigned long long LZ4IO_decompressLZ4F(LZ4IO_prefs_t* const prefs, dRess_t ress, FILE* srcFile, FILE* dstFile)
 {
     unsigned long long filesize = 0;
     LZ4F_errorCode_t nextToLoad;
@@ -937,8 +1029,8 @@ static unsigned long long LZ4IO_decompressLZ4F(dRess_t ress, FILE* srcFile, FILE
 
             /* Write Block */
             if (decodedBytes) {
-                if (!g_testMode)
-                    storedSkips = LZ4IO_fwriteSparse(dstFile, ress.dstBuffer, decodedBytes, storedSkips);
+                if (!prefs->testMode)
+                    storedSkips = LZ4IO_fwriteSparse(prefs, dstFile, ress.dstBuffer, decodedBytes, storedSkips);
                 filesize += decodedBytes;
                 DISPLAYUPDATE(2, "\rDecompressed : %u MB  ", (unsigned)(filesize>>20));
             }
@@ -949,7 +1041,7 @@ static unsigned long long LZ4IO_decompressLZ4F(dRess_t ress, FILE* srcFile, FILE
     /* can be out because readSize == 0, which could be an fread() error */
     if (ferror(srcFile)) EXM_THROW(67, "Read error");
 
-    if (!g_testMode) LZ4IO_fwriteSparseEnd(dstFile, storedSkips);
+    if (!prefs->testMode) LZ4IO_fwriteSparseEnd(dstFile, storedSkips);
     if (nextToLoad!=0) EXM_THROW(68, "Unfinished stream");
 
     return filesize;
@@ -958,7 +1050,7 @@ static unsigned long long LZ4IO_decompressLZ4F(dRess_t ress, FILE* srcFile, FILE
 
 #define PTSIZE  (64 KB)
 #define PTSIZET (PTSIZE / sizeof(size_t))
-static unsigned long long LZ4IO_passThrough(FILE* finput, FILE* foutput, unsigned char MNstore[MAGICNUMBER_SIZE])
+static unsigned long long LZ4IO_passThrough(LZ4IO_prefs_t* const prefs, FILE* finput, FILE* foutput, unsigned char MNstore[MAGICNUMBER_SIZE])
 {
 	size_t buffer[PTSIZET];
     size_t readBytes = 1;
@@ -971,7 +1063,7 @@ static unsigned long long LZ4IO_passThrough(FILE* finput, FILE* foutput, unsigne
     while (readBytes) {
         readBytes = fread(buffer, 1, PTSIZE, finput);
         total += readBytes;
-        storedSkips = LZ4IO_fwriteSparse(foutput, buffer, readBytes, storedSkips);
+        storedSkips = LZ4IO_fwriteSparse(prefs, foutput, buffer, readBytes, storedSkips);
     }
     if (ferror(finput)) EXM_THROW(51, "Read Error");
 
@@ -998,7 +1090,7 @@ static int fseek_u32(FILE *fp, unsigned offset, int where)
 }
 
 #define ENDOFSTREAM ((unsigned long long)-1)
-static unsigned long long selectDecoder(dRess_t ress, FILE* finput, FILE* foutput)
+static unsigned long long selectDecoder(LZ4IO_prefs_t* const prefs, dRess_t ress, FILE* finput, FILE* foutput)
 {
     unsigned char MNstore[MAGICNUMBER_SIZE];
     unsigned magicNumber;
@@ -1024,10 +1116,10 @@ static unsigned long long selectDecoder(dRess_t ress, FILE* finput, FILE* foutpu
     switch(magicNumber)
     {
     case LZ4IO_MAGICNUMBER:
-        return LZ4IO_decompressLZ4F(ress, finput, foutput);
+        return LZ4IO_decompressLZ4F(prefs, ress, finput, foutput);
     case LEGACY_MAGICNUMBER:
         DISPLAYLEVEL(4, "Detected : Legacy format \n");
-        return LZ4IO_decodeLegacyStream(finput, foutput);
+        return LZ4IO_decodeLegacyStream(prefs, finput, foutput);
     case LZ4IO_SKIPPABLE0:
         DISPLAYLEVEL(4, "Skipping detected skippable area \n");
         {   size_t const nbReadBytes = fread(MNstore, 1, 4, finput);
@@ -1044,9 +1136,9 @@ static unsigned long long selectDecoder(dRess_t ress, FILE* finput, FILE* foutpu
     default:
         if (nbFrames == 1) {  /* just started */
             /* Wrong magic number at the beginning of 1st stream */
-            if (!g_testMode && g_overwrite) {
+            if (!prefs->testMode && prefs->overwrite && prefs->passThrough) {
                 nbFrames = 0;
-                return LZ4IO_passThrough(finput, foutput, MNstore);
+                return LZ4IO_passThrough(prefs, finput, foutput, MNstore);
             }
             EXM_THROW(44,"Unrecognized header : file cannot be decoded");
         }
@@ -1061,7 +1153,7 @@ static unsigned long long selectDecoder(dRess_t ress, FILE* finput, FILE* foutpu
 }
 
 
-static int LZ4IO_decompressSrcFile(dRess_t ress, const char* input_filename, const char* output_filename)
+static int LZ4IO_decompressSrcFile(LZ4IO_prefs_t* const prefs, dRess_t ress, const char* input_filename, const char* output_filename)
 {
     FILE* const foutput = ress.dstFile;
     unsigned long long filesize = 0;
@@ -1073,14 +1165,14 @@ static int LZ4IO_decompressSrcFile(dRess_t ress, const char* input_filename, con
     /* Loop over multiple streams */
     for ( ; ; ) {  /* endless loop, see break condition */
         unsigned long long const decodedSize =
-                        selectDecoder(ress, finput, foutput);
+                        selectDecoder(prefs, ress, finput, foutput);
         if (decodedSize == ENDOFSTREAM) break;
         filesize += decodedSize;
     }
 
     /* Close input */
     fclose(finput);
-    if (g_removeSrcFile) {  /* --rm */
+    if (prefs->removeSrcFile) {  /* --rm */
         if (remove(input_filename))
             EXM_THROW(45, "Remove error : %s: %s", input_filename, strerror(errno));
     }
@@ -1094,11 +1186,11 @@ static int LZ4IO_decompressSrcFile(dRess_t ress, const char* input_filename, con
 }
 
 
-static int LZ4IO_decompressDstFile(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;
-    FILE* const foutput = LZ4IO_openDstFile(output_filename);
+    FILE* const foutput = LZ4IO_openDstFile(prefs, output_filename);
     if (foutput==NULL) return 1;   /* failure */
 
     if ( strcmp(input_filename, stdinmark)
@@ -1106,7 +1198,7 @@ static int LZ4IO_decompressDstFile(dRess_t ress, const char* input_filename, con
         stat_result = 1;
 
     ress.dstFile = foutput;
-    LZ4IO_decompressSrcFile(ress, input_filename, output_filename);
+    LZ4IO_decompressSrcFile(prefs, ress, input_filename, output_filename);
 
     fclose(foutput);
 
@@ -1122,12 +1214,12 @@ static int LZ4IO_decompressDstFile(dRess_t ress, const char* input_filename, con
 }
 
 
-int LZ4IO_decompressFilename(const char* input_filename, const char* output_filename)
+int LZ4IO_decompressFilename(LZ4IO_prefs_t* const prefs, const char* input_filename, const char* output_filename)
 {
-    dRess_t const ress = LZ4IO_createDResources();
+    dRess_t const ress = LZ4IO_createDResources(prefs);
     clock_t const start = clock();
 
-    int const missingFiles = LZ4IO_decompressDstFile(ress, input_filename, output_filename);
+    int const missingFiles = LZ4IO_decompressDstFile(prefs, ress, input_filename, output_filename);
 
     clock_t const end = clock();
     double const seconds = (double)(end - start) / CLOCKS_PER_SEC;
@@ -1138,7 +1230,7 @@ int LZ4IO_decompressFilename(const char* input_filename, const char* output_file
 }
 
 
-int LZ4IO_decompressMultipleFilenames(const char** inFileNamesTable, int ifntSize, const char* suffix)
+int LZ4IO_decompressMultipleFilenames(LZ4IO_prefs_t* const prefs, const char** inFileNamesTable, int ifntSize, const char* suffix)
 {
     int i;
     int skippedFiles = 0;
@@ -1146,16 +1238,16 @@ int LZ4IO_decompressMultipleFilenames(const char** inFileNamesTable, int ifntSiz
     char* outFileName = (char*)malloc(FNSPACE);
     size_t ofnSize = FNSPACE;
     size_t const suffixSize = strlen(suffix);
-    dRess_t ress = LZ4IO_createDResources();
+    dRess_t ress = LZ4IO_createDResources(prefs);
 
     if (outFileName==NULL) return ifntSize;   /* not enough memory */
-    ress.dstFile = LZ4IO_openDstFile(stdoutmark);
+    ress.dstFile = LZ4IO_openDstFile(prefs, stdoutmark);
 
     for (i=0; i<ifntSize; i++) {
         size_t const ifnSize = strlen(inFileNamesTable[i]);
         const char* const suffixPtr = inFileNamesTable[i] + ifnSize - suffixSize;
         if (!strcmp(suffix, stdoutmark)) {
-            missingFiles += LZ4IO_decompressSrcFile(ress, inFileNamesTable[i], stdoutmark);
+            missingFiles += LZ4IO_decompressSrcFile(prefs, ress, inFileNamesTable[i], stdoutmark);
             continue;
         }
         if (ofnSize <= ifnSize-suffixSize+1) { free(outFileName); ofnSize = ifnSize + 20; outFileName = (char*)malloc(ofnSize); if (outFileName==NULL) return ifntSize; }
@@ -1166,7 +1258,7 @@ int LZ4IO_decompressMultipleFilenames(const char** inFileNamesTable, int ifntSiz
         }
         memcpy(outFileName, inFileNamesTable[i], ifnSize - suffixSize);
         outFileName[ifnSize-suffixSize] = '\0';
-        missingFiles += LZ4IO_decompressDstFile(ress, inFileNamesTable[i], outFileName);
+        missingFiles += LZ4IO_decompressDstFile(prefs, ress, inFileNamesTable[i], outFileName);
     }
 
     LZ4IO_freeDResources(ress);
diff --git a/programs/lz4io.h b/programs/lz4io.h
index 22c5e3e..54d49be 100644
--- a/programs/lz4io.h
+++ b/programs/lz4io.h
@@ -48,61 +48,80 @@ static const char nulmark[] = "nul";
 static const char nulmark[] = "/dev/null";
 #endif
 
+/* ************************************************** */
+/* ****************** Type Definitions ************** */
+/* ************************************************** */
+
+typedef struct LZ4IO_prefs_s LZ4IO_prefs_t;
+
+LZ4IO_prefs_t* LZ4IO_defaultPreferences(void);
+void LZ4IO_freePreferences(LZ4IO_prefs_t* const prefs);
+
 
 /* ************************************************** */
 /* ****************** Functions ********************* */
 /* ************************************************** */
 
-int LZ4IO_compressFilename  (const char* input_filename, const char* output_filename, int compressionlevel);
-int LZ4IO_decompressFilename(const char* input_filename, const char* output_filename);
+/* if output_filename == stdoutmark, writes to stdout */
+int LZ4IO_compressFilename(LZ4IO_prefs_t* const prefs, const char* input_filename, const char* output_filename, int compressionlevel);
+int LZ4IO_decompressFilename(LZ4IO_prefs_t* const prefs, const char* input_filename, const char* output_filename);
 
-int LZ4IO_compressMultipleFilenames(const char** inFileNamesTable, int ifntSize, const char* suffix, int compressionlevel);
-int LZ4IO_decompressMultipleFilenames(const char** inFileNamesTable, int ifntSize, const char* suffix);
+/* if suffix == stdoutmark, writes to stdout */
+int LZ4IO_compressMultipleFilenames(LZ4IO_prefs_t* const prefs, const char** inFileNamesTable, int ifntSize, const char* suffix, int compressionlevel);
+int LZ4IO_decompressMultipleFilenames(LZ4IO_prefs_t* const prefs, const char** inFileNamesTable, int ifntSize, const char* suffix);
 
 
 /* ************************************************** */
 /* ****************** Parameters ******************** */
 /* ************************************************** */
 
-int LZ4IO_setDictionaryFilename(const char* dictionaryFilename);
+int LZ4IO_setDictionaryFilename(LZ4IO_prefs_t* const prefs, const char* dictionaryFilename);
+
+/* Default setting : passThrough = 0;
+   return : passThrough mode (0/1) */
+int LZ4IO_setPassThrough(LZ4IO_prefs_t* const prefs, int yes);
 
 /* Default setting : overwrite = 1;
    return : overwrite mode (0/1) */
-int LZ4IO_setOverwrite(int yes);
+int LZ4IO_setOverwrite(LZ4IO_prefs_t* const prefs, int yes);
 
 /* Default setting : testMode = 0;
    return : testMode (0/1) */
-int LZ4IO_setTestMode(int yes);
+int LZ4IO_setTestMode(LZ4IO_prefs_t* const prefs, int yes);
 
 /* blockSizeID : valid values : 4-5-6-7
    return : 0 if error, blockSize if OK */
-size_t LZ4IO_setBlockSizeID(unsigned blockSizeID);
+size_t LZ4IO_setBlockSizeID(LZ4IO_prefs_t* const prefs, unsigned blockSizeID);
+
+/* blockSize : valid values : 32 -> 4MB
+   return : 0 if error, actual blocksize if OK */
+size_t LZ4IO_setBlockSize(LZ4IO_prefs_t* const prefs, size_t blockSize);
 
 /* Default setting : independent blocks */
 typedef enum { LZ4IO_blockLinked=0, LZ4IO_blockIndependent} LZ4IO_blockMode_t;
-int LZ4IO_setBlockMode(LZ4IO_blockMode_t blockMode);
+int LZ4IO_setBlockMode(LZ4IO_prefs_t* const prefs, LZ4IO_blockMode_t blockMode);
 
 /* Default setting : no block checksum */
-int LZ4IO_setBlockChecksumMode(int xxhash);
+int LZ4IO_setBlockChecksumMode(LZ4IO_prefs_t* const prefs, int xxhash);
 
 /* Default setting : stream checksum enabled */
-int LZ4IO_setStreamChecksumMode(int xxhash);
+int LZ4IO_setStreamChecksumMode(LZ4IO_prefs_t* const prefs, int xxhash);
 
 /* Default setting : 0 (no notification) */
 int LZ4IO_setNotificationLevel(int level);
 
 /* Default setting : 0 (disabled) */
-int LZ4IO_setSparseFile(int enable);
+int LZ4IO_setSparseFile(LZ4IO_prefs_t* const prefs, int enable);
 
 /* Default setting : 0 == no content size present in frame header */
-int LZ4IO_setContentSize(int enable);
+int LZ4IO_setContentSize(LZ4IO_prefs_t* const prefs, int enable);
 
 /* Default setting : 0 == src file preserved */
-void LZ4IO_setRemoveSrcFile(unsigned flag);
+void LZ4IO_setRemoveSrcFile(LZ4IO_prefs_t* const prefs, unsigned flag);
 
 /* Default setting : 0 == favor compression ratio
  * Note : 1 only works for high compression levels (10+) */
-void LZ4IO_favorDecSpeed(int favor);
+void LZ4IO_favorDecSpeed(LZ4IO_prefs_t* const prefs, int favor);
 
 
 #endif  /* LZ4IO_H_237902873 */
diff --git a/programs/util.h b/programs/util.h
index d74db0d..6a35481 100644
--- a/programs/util.h
+++ b/programs/util.h
@@ -34,6 +34,7 @@ extern "C" {
 #include <stdlib.h>       /* malloc */
 #include <string.h>       /* strlen, strncpy */
 #include <stdio.h>        /* fprintf */
+#include <assert.h>
 #include <sys/types.h>    /* stat, utime */
 #include <sys/stat.h>     /* stat */
 #if defined(_MSC_VER)
@@ -44,6 +45,7 @@ extern "C" {
 #  include <utime.h>      /* utime */
 #endif
 #include <time.h>         /* time */
+#include <limits.h>       /* INT_MAX */
 #include <errno.h>
 
 
@@ -375,9 +377,9 @@ UTIL_STATIC U64 UTIL_getTotalFileSize(const char** fileNamesTable, unsigned nbFi
  * A modified version of realloc().
  * If UTIL_realloc() fails the original block is freed.
 */
-UTIL_STATIC void *UTIL_realloc(void *ptr, size_t size)
+UTIL_STATIC void* UTIL_realloc(void* ptr, size_t size)
 {
-    void *newptr = realloc(ptr, size);
+    void* newptr = realloc(ptr, size);
     if (newptr) return newptr;
     free(ptr);
     return NULL;
@@ -387,14 +389,14 @@ UTIL_STATIC void *UTIL_realloc(void *ptr, size_t size)
 #ifdef _WIN32
 #  define UTIL_HAS_CREATEFILELIST
 
-UTIL_STATIC int UTIL_prepareFileList(const char *dirName, char** bufStart, size_t* pos, char** bufEnd)
+UTIL_STATIC int UTIL_prepareFileList(const char* dirName, char** bufStart, size_t* pos, char** bufEnd)
 {
     char* path;
-    int dirLength, fnameLength, pathLength, nbFiles = 0;
+    size_t dirLength, nbFiles = 0;
     WIN32_FIND_DATAA cFile;
     HANDLE hFile;
 
-    dirLength = (int)strlen(dirName);
+    dirLength = strlen(dirName);
     path = (char*) malloc(dirLength + 3);
     if (!path) return 0;
 
@@ -411,7 +413,8 @@ UTIL_STATIC int UTIL_prepareFileList(const char *dirName, char** bufStart, size_
     free(path);
 
     do {
-        fnameLength = (int)strlen(cFile.cFileName);
+        size_t pathLength;
+        int const fnameLength = (int)strlen(cFile.cFileName);
         path = (char*) malloc(dirLength + fnameLength + 2);
         if (!path) { FindClose(hFile); return 0; }
         memcpy(path, dirName, dirLength);
@@ -443,7 +446,8 @@ UTIL_STATIC int UTIL_prepareFileList(const char *dirName, char** bufStart, size_
     } while (FindNextFileA(hFile, &cFile));
 
     FindClose(hFile);
-    return nbFiles;
+    assert(nbFiles < INT_MAX);
+    return (int)nbFiles;
 }
 
 #elif defined(__linux__) || (PLATFORM_POSIX_VERSION >= 200112L)  /* opendir, readdir require POSIX.1-2001 */
@@ -451,12 +455,11 @@ UTIL_STATIC int UTIL_prepareFileList(const char *dirName, char** bufStart, size_
 #  include <dirent.h>       /* opendir, readdir */
 #  include <string.h>       /* strerror, memcpy */
 
-UTIL_STATIC int UTIL_prepareFileList(const char *dirName, char** bufStart, size_t* pos, char** bufEnd)
+UTIL_STATIC int UTIL_prepareFileList(const char* dirName, char** bufStart, size_t* pos, char** bufEnd)
 {
-    DIR *dir;
-    struct dirent *entry;
-    char* path;
-    int dirLength, fnameLength, pathLength, nbFiles = 0;
+    DIR* dir;
+    struct dirent * entry;
+    int dirLength, nbFiles = 0;
 
     if (!(dir = opendir(dirName))) {
         fprintf(stderr, "Cannot open directory '%s': %s\n", dirName, strerror(errno));
@@ -466,6 +469,8 @@ UTIL_STATIC int UTIL_prepareFileList(const char *dirName, char** bufStart, size_
     dirLength = (int)strlen(dirName);
     errno = 0;
     while ((entry = readdir(dir)) != NULL) {
+        char* path;
+        int fnameLength, pathLength;
         if (strcmp (entry->d_name, "..") == 0 ||
             strcmp (entry->d_name, ".") == 0) continue;
         fnameLength = (int)strlen(entry->d_name);
@@ -508,7 +513,7 @@ UTIL_STATIC int UTIL_prepareFileList(const char *dirName, char** bufStart, size_
 
 #else
 
-UTIL_STATIC int UTIL_prepareFileList(const char *dirName, char** bufStart, size_t* pos, char** bufEnd)
+UTIL_STATIC int UTIL_prepareFileList(const char* dirName, char** bufStart, size_t* pos, char** bufEnd)
 {
     (void)bufStart; (void)bufEnd; (void)pos;
     fprintf(stderr, "Directory %s ignored (compiled without _WIN32 or _POSIX_C_SOURCE)\n", dirName);
@@ -523,12 +528,13 @@ UTIL_STATIC int UTIL_prepareFileList(const char *dirName, char** bufStart, size_
  * After finishing usage of the list the structures should be freed with UTIL_freeFileList(params: return value, allocatedBuffer)
  * In case of error UTIL_createFileList returns NULL and UTIL_freeFileList should not be called.
  */
-UTIL_STATIC const char** UTIL_createFileList(const char **inputNames, unsigned inputNamesNb, char** allocatedBuffer, unsigned* allocatedNamesNb)
+UTIL_STATIC const char**
+UTIL_createFileList(const char** inputNames, unsigned inputNamesNb, char** allocatedBuffer, unsigned* allocatedNamesNb)
 {
     size_t pos;
     unsigned i, nbFiles;
     char* buf = (char*)malloc(LIST_SIZE_INCREASE);
-    char* bufend = buf + LIST_SIZE_INCREASE;
+    size_t bufSize = LIST_SIZE_INCREASE;
     const char** fileTable;
 
     if (!buf) return NULL;
@@ -536,25 +542,28 @@ UTIL_STATIC const char** UTIL_createFileList(const char **inputNames, unsigned i
     for (i=0, pos=0, nbFiles=0; i<inputNamesNb; i++) {
         if (!UTIL_isDirectory(inputNames[i])) {
             size_t const len = strlen(inputNames[i]);
-            if (buf + pos + len >= bufend) {
-                ptrdiff_t newListSize = (bufend - buf) + LIST_SIZE_INCREASE;
+            if (pos + len >= bufSize) {
+                size_t newListSize = bufSize + LIST_SIZE_INCREASE;
                 buf = (char*)UTIL_realloc(buf, newListSize);
-                bufend = buf + newListSize;
+                bufSize = newListSize;
                 if (!buf) return NULL;
             }
-            if (buf + pos + len < bufend) {
-                strncpy(buf + pos, inputNames[i], bufend - (buf + pos));
+            if (pos + len < bufSize) {
+                strncpy(buf + pos, inputNames[i], bufSize - pos);
                 pos += len + 1;
                 nbFiles++;
             }
         } else {
-            nbFiles += UTIL_prepareFileList(inputNames[i], &buf, &pos, &bufend);
+            char* bufend = buf + bufSize;
+            nbFiles += (unsigned)UTIL_prepareFileList(inputNames[i], &buf, &pos, &bufend);
             if (buf == NULL) return NULL;
+            assert(bufend > buf);
+            bufSize = (size_t)(bufend - buf);
     }   }
 
     if (nbFiles == 0) { free(buf); return NULL; }
 
-    fileTable = (const char**)malloc((nbFiles+1) * sizeof(const char*));
+    fileTable = (const char**)malloc(((size_t)nbFiles+1) * sizeof(const char*));
     if (!fileTable) { free(buf); return NULL; }
 
     for (i=0, pos=0; i<nbFiles; i++) {
@@ -562,7 +571,11 @@ UTIL_STATIC const char** UTIL_createFileList(const char **inputNames, unsigned i
         pos += strlen(fileTable[i]) + 1;
     }
 
-    if (buf + pos > bufend) { free(buf); free((void*)fileTable); return NULL; }
+    if (pos > bufSize) {
+        free(buf);
+        free((void*)fileTable);
+        return NULL;
+    }   /* can this happen ? */
 
     *allocatedBuffer = buf;
     *allocatedNamesNb = nbFiles;
@@ -571,7 +584,8 @@ UTIL_STATIC const char** UTIL_createFileList(const char **inputNames, unsigned i
 }
 
 
-UTIL_STATIC void UTIL_freeFileList(const char** filenameTable, char* allocatedBuffer)
+UTIL_STATIC void
+UTIL_freeFileList(const char** filenameTable, char* allocatedBuffer)
 {
     if (allocatedBuffer) free(allocatedBuffer);
     if (filenameTable) free((void*)filenameTable);