ddidderr/zstd-rs
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fixed several minor issues detected by scan-build

Browse Source 
only notable one :
writeNCount() resists better vs invalid distributions
(though it should never happen within zstd anyway)
This commit is contained in:
Yann Collet
2018-08-14 16:55:35 -07:00
parent a25d8000ec
commit 6e66bbf5dd
10 changed files with 67 additions and 56 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/compress/fse_compress.c
+37 -28
View File
@@ -83,7 +83,9 @@
* wkspSize should be sized to handle worst case situation, which is `1<<max_tableLog * sizeof(FSE_FUNCTION_TYPE)`
* workSpace must also be properly aligned with FSE_FUNCTION_TYPE requirements
*/
size_t FSE_buildCTable_wksp(FSE_CTable* ct, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)
size_t FSE_buildCTable_wksp(FSE_CTable* ct,
const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog,
void* workSpace, size_t wkspSize)
{
U32 const tableSize = 1 << tableLog;
U32 const tableMask = tableSize - 1;
@@ -101,10 +103,14 @@ size_t FSE_buildCTable_wksp(FSE_CTable* ct, const short* normalizedCounter, unsi
if (((size_t)1 << tableLog) * sizeof(FSE_FUNCTION_TYPE) > wkspSize) return ERROR(tableLog_tooLarge);
tableU16[-2] = (U16) tableLog;
tableU16[-1] = (U16) maxSymbolValue;
assert(tableLog < 16); /* required for the threshold strategy to work */
assert(tableLog < 16); /* required for threshold strategy to work */
/* For explanations on how to distribute symbol values over the table :
* http://fastcompression.blogspot.fr/2014/02/fse-distributing-symbol-values.html */
* http://fastcompression.blogspot.fr/2014/02/fse-distributing-symbol-values.html */
#ifdef __clang_analyzer__
memset(tableSymbol, 0, sizeof(*tableSymbol) * tableSize); /* useless initialization, just to keep scan-build happy */
#endif
/* symbol start positions */
{ U32 u;
@@ -124,13 +130,15 @@ size_t FSE_buildCTable_wksp(FSE_CTable* ct, const short* normalizedCounter, unsi
U32 symbol;
for (symbol=0; symbol<=maxSymbolValue; symbol++) {
int nbOccurences;
for (nbOccurences=0; nbOccurences<normalizedCounter[symbol]; nbOccurences++) {
int const freq = normalizedCounter[symbol];
for (nbOccurences=0; nbOccurences<freq; nbOccurences++) {
tableSymbol[position] = (FSE_FUNCTION_TYPE)symbol;
position = (position + step) & tableMask;
while (position > highThreshold) position = (position + step) & tableMask; /* Low proba area */
while (position > highThreshold)
position = (position + step) & tableMask; /* Low proba area */
} }
if (position!=0) return ERROR(GENERIC); /* Must have gone through all positions */
assert(position==0); /* Must have initialized all positions */
}
/* Build table */
@@ -201,9 +209,10 @@ size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog)
return maxSymbolValue ? maxHeaderSize : FSE_NCOUNTBOUND; /* maxSymbolValue==0 ? use default */
}
static size_t FSE_writeNCount_generic (void* header, size_t headerBufferSize,
const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog,
unsigned writeIsSafe)
static size_t
FSE_writeNCount_generic (void* header, size_t headerBufferSize,
const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog,
unsigned writeIsSafe)
{
BYTE* const ostart = (BYTE*) header;
BYTE* out = ostart;
@@ -212,13 +221,12 @@ static size_t FSE_writeNCount_generic (void* header, size_t headerBufferSize,
const int tableSize = 1 << tableLog;
int remaining;
int threshold;
U32 bitStream;
int bitCount;
unsigned charnum = 0;
int previous0 = 0;
U32 bitStream = 0;
int bitCount = 0;
unsigned symbol = 0;
unsigned const alphabetSize = maxSymbolValue + 1;
int previousIs0 = 0;
bitStream = 0;
bitCount = 0;
/* Table Size */
bitStream += (tableLog-FSE_MIN_TABLELOG) << bitCount;
bitCount += 4;
@@ -228,11 +236,11 @@ static size_t FSE_writeNCount_generic (void* header, size_t headerBufferSize,
threshold = tableSize;
nbBits = tableLog+1;
while (remaining>1) { /* stops at 1 */
if (previous0) {
unsigned start = charnum;
while (!normalizedCounter[charnum]) charnum++;
while (charnum >= start+24) {
while ((symbol < alphabetSize) && (remaining>1)) { /* stops at 1 */
if (previousIs0) {
unsigned start = symbol;
while ((symbol < alphabetSize) && !normalizedCounter[symbol]) symbol++;
while (symbol >= start+24) {
start+=24;
bitStream += 0xFFFFU << bitCount;
if ((!writeIsSafe) && (out > oend-2)) return ERROR(dstSize_tooSmall); /* Buffer overflow */
@@ -241,12 +249,12 @@ static size_t FSE_writeNCount_generic (void* header, size_t headerBufferSize,
out+=2;
bitStream>>=16;
}
while (charnum >= start+3) {
while (symbol >= start+3) {
start+=3;
bitStream += 3 << bitCount;
bitCount += 2;
}
bitStream += (charnum-start) << bitCount;
bitStream += (symbol-start) << bitCount;
bitCount += 2;
if (bitCount>16) {
if ((!writeIsSafe) && (out > oend - 2)) return ERROR(dstSize_tooSmall); /* Buffer overflow */
@@ -256,15 +264,15 @@ static size_t FSE_writeNCount_generic (void* header, size_t headerBufferSize,
bitStream >>= 16;
bitCount -= 16;
} }
{ int count = normalizedCounter[charnum++];
int const max = (2*threshold-1)-remaining;
{ int count = normalizedCounter[symbol++];
int const max = (2*threshold-1) - remaining;
remaining -= count < 0 ? -count : count;
count++; /* +1 for extra accuracy */
if (count>=threshold) count += max; /* [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[ */
bitStream += count << bitCount;
bitCount += nbBits;
bitCount -= (count<max);
previous0 = (count==1);
previousIs0 = (count==1);
if (remaining<1) return ERROR(GENERIC);
while (remaining<threshold) { nbBits--; threshold>>=1; }
}
@@ -277,14 +285,15 @@ static size_t FSE_writeNCount_generic (void* header, size_t headerBufferSize,
bitCount -= 16;
} }
if (remaining != 1) return ERROR(GENERIC); /* incorrect normalized distribution */
assert(symbol <= alphabetSize);
/* flush remaining bitStream */
if ((!writeIsSafe) && (out > oend - 2)) return ERROR(dstSize_tooSmall); /* Buffer overflow */
out[0] = (BYTE)bitStream;
out[1] = (BYTE)(bitStream>>8);
out+= (bitCount+7) /8;
if (charnum > maxSymbolValue + 1) return ERROR(GENERIC);
return (out-ostart);
}
@@ -297,7 +306,7 @@ size_t FSE_writeNCount (void* buffer, size_t bufferSize, const short* normalized
if (bufferSize < FSE_NCountWriteBound(maxSymbolValue, tableLog))
return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 0);
return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 1);
return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 1 /* write in buffer is safe */);
}
lib/compress/zstd_compress.c
-1
View File
@@ -1147,7 +1147,6 @@ static size_t ZSTD_resetCCtx_internal(ZSTD_CCtx* zc,
if (zc->workSpace == NULL) return ERROR(memory_allocation);
zc->workSpaceSize = neededSpace;
zc->workSpaceOversizedDuration = 0;
ptr = zc->workSpace;
/* Statically sized space.
* entropyWorkspace never moves,
lib/compress/zstd_opt.c
+1 -1
View File
@@ -970,7 +970,7 @@ _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
U32 seqPos = cur;
DEBUGLOG(6, "start reverse traversal (last_pos:%u, cur:%u)",
last_pos, cur);
last_pos, cur); (void)last_pos;
assert(storeEnd < ZSTD_OPT_NUM);
DEBUGLOG(6, "last sequence copied into pos=%u (llen=%u,mlen=%u,ofc=%u)",
storeEnd, lastSequence.litlen, lastSequence.mlen, lastSequence.off);