From 734eff70b8da08aefb480b2676981b273ae1d625 Mon Sep 17 00:00:00 2001
From: Ephraim Park <ephiepark@fb.com>
Date: Wed, 26 Jun 2019 16:39:00 -0700
Subject: [PATCH 1/2] enable repeat mode on rle

---
 tests/decodecorpus.c | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/tests/decodecorpus.c b/tests/decodecorpus.c
index 9910d3c55..df40862b2 100644
--- a/tests/decodecorpus.c
+++ b/tests/decodecorpus.c
@@ -840,16 +840,16 @@ static size_t writeSequences(U32* seed, frame_t* frame, seqStore_t* seqStorePtr,
     {   unsigned max = MaxLL;
         size_t const mostFrequent = HIST_countFast_wksp(count, &max, llCodeTable, nbSeq, WKSP, sizeof(WKSP));   /* cannot fail */
         assert(!HIST_isError(mostFrequent));
-        if (mostFrequent == nbSeq) {
-            /* do RLE if we have the chance */
-            *op++ = llCodeTable[0];
-            FSE_buildCTable_rle(CTable_LitLength, (BYTE)max);
-            LLtype = set_rle;
-        } else if (frame->stats.fseInit && !(RAND(seed) & 3) &&
+        if (frame->stats.fseInit && !(RAND(seed) & 3) &&
                    isSymbolSubset(llCodeTable, nbSeq,
                                   frame->stats.litlengthSymbolSet, 35)) {
             /* maybe do repeat mode if we're allowed to */
             LLtype = set_repeat;
+        } else if (mostFrequent == nbSeq) {
+            /* do RLE if we have the chance */
+            *op++ = llCodeTable[0];
+            FSE_buildCTable_rle(CTable_LitLength, (BYTE)max);
+            LLtype = set_rle;
         } else if (!(RAND(seed) & 3)) {
             /* maybe use the default distribution */
             FSE_buildCTable_wksp(CTable_LitLength, LL_defaultNorm, MaxLL, LL_defaultNormLog, scratchBuffer, sizeof(scratchBuffer));
@@ -872,14 +872,14 @@ static size_t writeSequences(U32* seed, frame_t* frame, seqStore_t* seqStorePtr,
     {   unsigned max = MaxOff;
         size_t const mostFrequent = HIST_countFast_wksp(count, &max, ofCodeTable, nbSeq, WKSP, sizeof(WKSP));   /* cannot fail */
         assert(!HIST_isError(mostFrequent));
-        if (mostFrequent == nbSeq) {
-            *op++ = ofCodeTable[0];
-            FSE_buildCTable_rle(CTable_OffsetBits, (BYTE)max);
-            Offtype = set_rle;
-        } else if (frame->stats.fseInit && !(RAND(seed) & 3) &&
+        if (frame->stats.fseInit && !(RAND(seed) & 3) &&
                    isSymbolSubset(ofCodeTable, nbSeq,
                                   frame->stats.offsetSymbolSet, 28)) {
             Offtype = set_repeat;
+        } else if (mostFrequent == nbSeq) {
+            *op++ = ofCodeTable[0];
+            FSE_buildCTable_rle(CTable_OffsetBits, (BYTE)max);
+            Offtype = set_rle;
         } else if (!(RAND(seed) & 3)) {
             FSE_buildCTable_wksp(CTable_OffsetBits, OF_defaultNorm, DefaultMaxOff, OF_defaultNormLog, scratchBuffer, sizeof(scratchBuffer));
             Offtype = set_basic;
@@ -900,14 +900,14 @@ static size_t writeSequences(U32* seed, frame_t* frame, seqStore_t* seqStorePtr,
     {   unsigned max = MaxML;
         size_t const mostFrequent = HIST_countFast_wksp(count, &max, mlCodeTable, nbSeq, WKSP, sizeof(WKSP));   /* cannot fail */
         assert(!HIST_isError(mostFrequent));
-        if (mostFrequent == nbSeq) {
-            *op++ = *mlCodeTable;
-            FSE_buildCTable_rle(CTable_MatchLength, (BYTE)max);
-            MLtype = set_rle;
-        } else if (frame->stats.fseInit && !(RAND(seed) & 3) &&
+        if (frame->stats.fseInit && !(RAND(seed) & 3) &&
                    isSymbolSubset(mlCodeTable, nbSeq,
                                   frame->stats.matchlengthSymbolSet, 52)) {
             MLtype = set_repeat;
+        } else if (mostFrequent == nbSeq) {
+            *op++ = *mlCodeTable;
+            FSE_buildCTable_rle(CTable_MatchLength, (BYTE)max);
+            MLtype = set_rle;
         } else if (!(RAND(seed) & 3)) {
             /* sometimes do default distribution */
             FSE_buildCTable_wksp(CTable_MatchLength, ML_defaultNorm, MaxML, ML_defaultNormLog, scratchBuffer, sizeof(scratchBuffer));

From c7c1ba3a19fea25bef9efe8dcfd82fe97fc9483a Mon Sep 17 00:00:00 2001
From: Ephraim Park <ephiepark@fb.com>
Date: Wed, 26 Jun 2019 16:43:37 -0700
Subject: [PATCH 2/2] Fix a constraint stricter than the spec

---
 lib/decompress/zstd_decompress_block.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/decompress/zstd_decompress_block.c b/lib/decompress/zstd_decompress_block.c
index 7707c28bb..741784fdf 100644
--- a/lib/decompress/zstd_decompress_block.c
+++ b/lib/decompress/zstd_decompress_block.c
@@ -505,7 +505,7 @@ size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr,
     *nbSeqPtr = nbSeq;
 
     /* FSE table descriptors */
-    RETURN_ERROR_IF(ip+4 > iend, srcSize_wrong); /* minimum possible size */
+    RETURN_ERROR_IF(ip+1 > iend, srcSize_wrong); /* minimum possible size: 1 byte for symbol encoding types */
     {   symbolEncodingType_e const LLtype = (symbolEncodingType_e)(*ip >> 6);
         symbolEncodingType_e const OFtype = (symbolEncodingType_e)((*ip >> 4) & 3);
         symbolEncodingType_e const MLtype = (symbolEncodingType_e)((*ip >> 2) & 3);