Added DDict unit test in fuzzer

also : slightly modified loadEntropy :
know src must points at start of dictionary

lib/decompress/zstd_decompress.c

@@ -97,10 +97,10 @@ struct ZSTD_DCtx_s
     FSE_DTable OFTable[FSE_DTABLE_SIZE_U32(OffFSELog)];
     FSE_DTable MLTable[FSE_DTABLE_SIZE_U32(MLFSELog)];
     HUF_DTable hufTable[HUF_DTABLE_SIZE(HufLog)];  /* can accommodate HUF_decompress4X */
-    const void* previousDstEnd;
+    const void* previousDstEnd;   /* detect continuity */
-    const void* base;
+    const void* base;             /* start of current segment */
-    const void* vBase;
+    const void* vBase;            /* virtual start of previous segment if it was just before current one */
-    const void* dictEnd;
+    const void* dictEnd;          /* end of previous segment */
     size_t expected;
     U32 rep[ZSTD_REP_NUM];
     ZSTD_frameParams fParams;
@@ -1579,8 +1579,8 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
 
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
         if (ZSTD_isLegacy(src, srcSize)) {
-            size_t const frameSize = ZSTD_findFrameCompressedSizeLegacy(src, srcSize);
             size_t decodedSize;
+            size_t const frameSize = ZSTD_findFrameCompressedSizeLegacy(src, srcSize);
             if (ZSTD_isError(frameSize)) return frameSize;
 
             decodedSize = ZSTD_decompressLegacy(dst, dstCapacity, src, frameSize, dict, dictSize);
@@ -1625,8 +1625,7 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
         }
         ZSTD_checkContinuity(dctx, dst);
 
-        {
+        {   const size_t res = ZSTD_decompressFrame(dctx, dst, dstCapacity,
-            const size_t res = ZSTD_decompressFrame(dctx, dst, dstCapacity,
                                                     &src, &srcSize);
             if (ZSTD_isError(res)) return res;
             /* don't need to bounds check this, ZSTD_decompressFrame will have
@@ -1636,9 +1635,7 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
         }
     }
 
-    if (srcSize) {
+    if (srcSize) return ERROR(srcSize_wrong); /* input not entirely consumed */
-        return ERROR(srcSize_wrong);
-    }
 
     return (BYTE*)dst - (BYTE*)dststart;
 }
@@ -1835,12 +1832,18 @@ static size_t ZSTD_refDictContent(ZSTD_DCtx* dctx, const void* dict, size_t dict
     return 0;
 }
 
+/* ZSTD_loadEntropy() :
+ * dict : must point at beginning of dictionary
+ * @return : size of entropy tables read */
 static size_t ZSTD_loadEntropy(ZSTD_DCtx* dctx, const void* const dict, size_t const dictSize)
 {
     const BYTE* dictPtr = (const BYTE*)dict;
     const BYTE* const dictEnd = dictPtr + dictSize;
 
-    {   size_t const hSize = HUF_readDTableX4(dctx->hufTable, dict, dictSize);
+    if (dictSize <= 8) return ERROR(dictionary_corrupted);
+    dictPtr += 8;   /* skip header = magic + dictID */
+
+    {   size_t const hSize = HUF_readDTableX4(dctx->hufTable, dictPtr, dictEnd-dictPtr);
         if (HUF_isError(hSize)) return ERROR(dictionary_corrupted);
         dictPtr += hSize;
     }
@@ -1892,8 +1895,6 @@ static size_t ZSTD_decompress_insertDictionary(ZSTD_DCtx* dctx, const void* dict
     dctx->dictID = MEM_readLE32((const char*)dict + 4);
 
     /* load entropy tables */
-    dict = (const char*)dict + 8;
-    dictSize -= 8;
     {   size_t const eSize = ZSTD_loadEntropy(dctx, dict, dictSize);
         if (ZSTD_isError(eSize)) return ERROR(dictionary_corrupted);
         dict = (const char*)dict + eSize;
@@ -1934,27 +1935,27 @@ ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, unsigne
             ZSTD_free(dctx, customMem);
             return NULL;
         }
+        ddict->refContext = dctx;
 
         if ((byReference) || (!dict) || (!dictSize)) {
             ddict->dictBuffer = NULL;
             ddict->dictContent = dict;
         } else {
             void* const internalBuffer = ZSTD_malloc(dictSize, customMem);
-            if (!internalBuffer) { ZSTD_free(dctx, customMem); ZSTD_free(ddict, customMem); return NULL; }
+            if (!internalBuffer) { ZSTD_freeDDict(ddict); return NULL; }
             memcpy(internalBuffer, dict, dictSize);
             ddict->dictBuffer = internalBuffer;
             ddict->dictContent = internalBuffer;
         }
-        {   size_t const errorCode = ZSTD_decompressBegin_usingDict(dctx, ddict->dictContent, dictSize);
+        /* parse dictionary content */
+        {   //size_t const errorCode = ZSTD_decompressBegin_usingDict(dctx, ddict->dictContent, dictSize);
+            size_t const errorCode = ZSTD_decompress_insertDictionary(dctx, ddict->dictContent, dictSize);
             if (ZSTD_isError(errorCode)) {
-                ZSTD_free(ddict->dictBuffer, customMem);
+                ZSTD_freeDDict(ddict);
-                ZSTD_free(ddict, customMem);
-                ZSTD_free(dctx, customMem);
                 return NULL;
         }   }
 
         ddict->dictSize = dictSize;
-        ddict->refContext = dctx;
         return ddict;
     }
 }

tests/fuzzer.c

@@ -256,6 +256,14 @@ static int basicUnitTests(U32 seed, double compressibility)
                   if (r != CNBuffSize - dictSize) goto _output_error);
         DISPLAYLEVEL(4, "OK \n");
 
+        DISPLAYLEVEL(4, "test%3i : decompress with DDict : ", testNb++);
+        {   ZSTD_DDict* const ddict = ZSTD_createDDict(CNBuffer, dictSize);
+            size_t const r = ZSTD_decompress_usingDDict(dctx, decodedBuffer, CNBuffSize, compressedBuffer, cSize, ddict);
+            if (r != CNBuffSize - dictSize) goto _output_error;
+            DISPLAYLEVEL(4, "OK (size of DDict : %u) \n", (U32)ZSTD_sizeof_DDict(ddict));
+            ZSTD_freeDDict(ddict);
+        }
+
         DISPLAYLEVEL(4, "test%3i : check content size on duplicated context : ", testNb++);
         {   size_t const testSize = CNBuffSize / 3;
             {   ZSTD_parameters p = ZSTD_getParams(2, testSize, dictSize);