Fix undefined behavior when srcSize==1
diff --git a/lib/common/bitstream.h b/lib/common/bitstream.h
index 06121f2..c6f0012 100644
--- a/lib/common/bitstream.h
+++ b/lib/common/bitstream.h
@@ -169,25 +169,28 @@
****************************************************************/
MEM_STATIC unsigned BIT_highbit32 (register U32 val)
{
+ assert(val != 0);
+ {
# if defined(_MSC_VER) /* Visual */
- unsigned long r=0;
- _BitScanReverse ( &r, val );
- return (unsigned) r;
+ unsigned long r=0;
+ _BitScanReverse ( &r, val );
+ return (unsigned) r;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
- return 31 - __builtin_clz (val);
+ return 31 - __builtin_clz (val);
# else /* Software version */
- static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29,
- 11, 14, 16, 18, 22, 25, 3, 30,
- 8, 12, 20, 28, 15, 17, 24, 7,
- 19, 27, 23, 6, 26, 5, 4, 31 };
- U32 v = val;
- v |= v >> 1;
- v |= v >> 2;
- v |= v >> 4;
- v |= v >> 8;
- v |= v >> 16;
- return DeBruijnClz[ (U32) (v * 0x07C4ACDDU) >> 27];
+ static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29,
+ 11, 14, 16, 18, 22, 25, 3, 30,
+ 8, 12, 20, 28, 15, 17, 24, 7,
+ 19, 27, 23, 6, 26, 5, 4, 31 };
+ U32 v = val;
+ v |= v >> 1;
+ v |= v >> 2;
+ v |= v >> 4;
+ v |= v >> 8;
+ v |= v >> 16;
+ return DeBruijnClz[ (U32) (v * 0x07C4ACDDU) >> 27];
# endif
+ }
}
/*===== Local Constants =====*/
diff --git a/lib/common/zstd_internal.h b/lib/common/zstd_internal.h
index 2610528..ac1f398 100644
--- a/lib/common/zstd_internal.h
+++ b/lib/common/zstd_internal.h
@@ -268,24 +268,27 @@
MEM_STATIC U32 ZSTD_highbit32(U32 val)
{
+ assert(val != 0);
+ {
# if defined(_MSC_VER) /* Visual */
- unsigned long r=0;
- _BitScanReverse(&r, val);
- return (unsigned)r;
+ unsigned long r=0;
+ _BitScanReverse(&r, val);
+ return (unsigned)r;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* GCC Intrinsic */
- return 31 - __builtin_clz(val);
+ return 31 - __builtin_clz(val);
# else /* Software version */
- static const int DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 };
- U32 v = val;
- int r;
- v |= v >> 1;
- v |= v >> 2;
- v |= v >> 4;
- v |= v >> 8;
- v |= v >> 16;
- r = DeBruijnClz[(U32)(v * 0x07C4ACDDU) >> 27];
- return r;
+ static const int DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 };
+ U32 v = val;
+ int r;
+ v |= v >> 1;
+ v |= v >> 2;
+ v |= v >> 4;
+ v |= v >> 8;
+ v |= v >> 16;
+ r = DeBruijnClz[(U32)(v * 0x07C4ACDDU) >> 27];
+ return r;
# endif
+ }
}
diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 0322c03..31e9415 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -497,7 +497,8 @@
{ U32 const minSrcSize = (srcSize==0) ? 500 : 0;
U64 const rSize = srcSize + dictSize + minSrcSize;
if (rSize < ((U64)1<<ZSTD_WINDOWLOG_MAX)) {
- U32 const srcLog = MAX(ZSTD_HASHLOG_MIN, ZSTD_highbit32((U32)(rSize)-1) + 1);
+ U32 const srcLog =
+ MAX(ZSTD_HASHLOG_MIN, (rSize==1) ? 1 : ZSTD_highbit32((U32)(rSize)-1) + 1);
if (cPar.windowLog > srcLog) cPar.windowLog = srcLog;
} }
if (cPar.hashLog > cPar.windowLog) cPar.hashLog = cPar.windowLog;
