From 81441e246223e91ccc3ce1e146df8874ec9c526e Mon Sep 17 00:00:00 2001
From: Tim Zakian <2895723+tzakian@users.noreply.github.com>
Date: Wed, 9 Jan 2019 13:42:12 -0800
Subject: Make fact that certain variables that are passed into
 LZ4HC_encodeSequence are changed by the function call

---
 lib/lz4hc.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/lib/lz4hc.c b/lib/lz4hc.c
index 86db155..129bf0c 100644
--- a/lib/lz4hc.c
+++ b/lib/lz4hc.c
@@ -88,6 +88,8 @@ typedef enum {
 #define HASH_FUNCTION(i)         (((i) * 2654435761U) >> ((MINMATCH*8)-LZ4HC_HASH_LOG))
 #define DELTANEXTMAXD(p)         chainTable[(p) & LZ4HC_MAXD_MASK]    /* flexible, LZ4HC_MAXD dependent */
 #define DELTANEXTU16(table, pos) table[(U16)(pos)]   /* faster */
+/* Make fields passed to, and updated by LZ4HC_encodeSequence explicit */
+#define UPDATABLE(ip, op, anchor) &ip, &op, &anchor
 
 static U32 LZ4HC_hashPtr(const void* ptr) { return HASH_FUNCTION(LZ4_read32(ptr)); }
 
@@ -533,7 +535,7 @@ _Search2:
 
         if (ml2 == ml) { /* No better match => encode ML1 */
             optr = op;
-            if (LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ref, limit, oend)) goto _dest_overflow;
+            if (LZ4HC_encodeSequence(UPDATABLE(ip, op, anchor), ml, ref, limit, oend)) goto _dest_overflow;
             continue;
         }
 
@@ -581,10 +583,10 @@ _Search3:
             if (start2 < ip+ml)  ml = (int)(start2 - ip);
             /* Now, encode 2 sequences */
             optr = op;
-            if (LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ref, limit, oend)) goto _dest_overflow;
+            if (LZ4HC_encodeSequence(UPDATABLE(ip, op, anchor), ml, ref, limit, oend)) goto _dest_overflow;
             ip = start2;
             optr = op;
-            if (LZ4HC_encodeSequence(&ip, &op, &anchor, ml2, ref2, limit, oend)) goto _dest_overflow;
+            if (LZ4HC_encodeSequence(UPDATABLE(ip, op, anchor), ml2, ref2, limit, oend)) goto _dest_overflow;
             continue;
         }
 
@@ -603,7 +605,7 @@ _Search3:
                 }
 
                 optr = op;
-                if (LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ref, limit, oend)) goto _dest_overflow;
+                if (LZ4HC_encodeSequence(UPDATABLE(ip, op, anchor), ml, ref, limit, oend)) goto _dest_overflow;
                 ip  = start3;
                 ref = ref3;
                 ml  = ml3;
@@ -641,7 +643,7 @@ _Search3:
             }
         }
         optr = op;
-        if (LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ref, limit, oend)) goto _dest_overflow;
+        if (LZ4HC_encodeSequence(UPDATABLE(ip, op, anchor), ml, ref, limit, oend)) goto _dest_overflow;
 
         /* ML2 becomes ML1 */
         ip = start2; ref = ref2; ml = ml2;
@@ -1206,7 +1208,7 @@ static int LZ4HC_compress_optimal ( LZ4HC_CCtx_internal* ctx,
              int const firstML = firstMatch.len;
              const BYTE* const matchPos = ip - firstMatch.off;
              opSaved = op;
-             if ( LZ4HC_encodeSequence(&ip, &op, &anchor, firstML, matchPos, limit, oend) )   /* updates ip, op and anchor */
+             if ( LZ4HC_encodeSequence(UPDATABLE(ip, op, anchor), firstML, matchPos, limit, oend) )   /* updates ip, op and anchor */
                  goto _dest_overflow;
              continue;
          }
@@ -1378,7 +1380,7 @@ static int LZ4HC_compress_optimal ( LZ4HC_CCtx_internal* ctx,
                  assert(ml >= MINMATCH);
                  assert((offset >= 1) && (offset <= MAX_DISTANCE));
                  opSaved = op;
-                 if ( LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ip - offset, limit, oend) )   /* updates ip, op and anchor */
+                 if ( LZ4HC_encodeSequence(UPDATABLE(ip, op, anchor), ml, ip - offset, limit, oend) )   /* updates ip, op and anchor */
                      goto _dest_overflow;
          }   }
      }  /* while (ip <= mflimit) */
-- 
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