From f81f3a254e2dc0a2f951340c9723c7bc504118b6 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Fri, 13 Nov 2020 16:44:39 -0800
Subject: LZ4IO_fwriteSparse doesn't need writable prefs

---
 programs/lz4io.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/programs/lz4io.c b/programs/lz4io.c
index baebd17..2bd0401 100644
--- a/programs/lz4io.c
+++ b/programs/lz4io.c
@@ -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)
@@ -858,7 +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 ;
@@ -868,7 +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;
@@ -971,7 +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");
 
@@ -1076,7 +1081,7 @@ 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));
             }
@@ -1112,7 +1117,7 @@ LZ4IO_passThrough(LZ4IO_prefs_t* const prefs,
     while (readBytes) {
         readBytes = fread(buffer, 1, PTSIZE, finput);
         total += readBytes;
-        storedSkips = LZ4IO_fwriteSparse(prefs, foutput, buffer, readBytes, storedSkips);
+        storedSkips = LZ4IO_fwriteSparse(foutput, buffer, readBytes, prefs->sparseFileSupport, storedSkips);
     }
     if (ferror(finput)) EXM_THROW(51, "Read Error");
 
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