Add cSize regression test to fuzzer.c

lib/compress/zstd_ldm.c

@@ -575,6 +575,8 @@ size_t ZSTD_ldm_blockCompress(rawSeqStore_t* rawSeqStore,
     BYTE const* const iend = istart + srcSize;
     /* Input positions */
     BYTE const* ip = istart;
+
+    /* If using opt parser, use LDMs only as candidates rather than always accepting them */
     if (cParams->strategy >= ZSTD_btopt) {
         size_t lastLLSize;
         ms->ldmSeqStore = *rawSeqStore;

lib/compress/zstd_opt.c

@@ -774,7 +774,9 @@ FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches (
 static void ZSTD_opt_skipBytesInLdmSeqStore(rawSeqStore_t* ldmSeqStore, size_t nbBytes) {
     while (nbBytes && ldmSeqStore->pos < ldmSeqStore->size) {
         rawSeq currSeq = ldmSeqStore->seq[ldmSeqStore->pos];
+        /* posInSequence necessarily must never represent a value beyond the sequence */
         assert(ldmSeqStore->posInSequence <= currSeq.matchLength + currSeq.litLength);
+
         if (nbBytes <= currSeq.litLength) {
             ldmSeqStore->posInSequence += nbBytes;
             return;
@@ -782,6 +784,7 @@ static void ZSTD_opt_skipBytesInLdmSeqStore(rawSeqStore_t* ldmSeqStore, size_t n
             ldmSeqStore->posInSequence += currSeq.litLength;
             nbBytes -= currSeq.litLength;
         }
+        
         if (nbBytes < currSeq.matchLength) {
             ldmSeqStore->posInSequence += nbBytes;
             return;