From 9c5809820081cbee89984052763846e29c67bd0e Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Mon, 29 Oct 2018 13:57:37 -0700
Subject: [PATCH] fixed memcpy() on NULL warning

memcpy(NULL, src, 0) is undefined behavior.
---
 lib/decompress/zstd_decompress.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 2491f4dfb..61826e3af 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -508,7 +508,10 @@ static size_t ZSTD_copyRawBlock(void* dst, size_t dstCapacity,
                           const void* src, size_t srcSize)
 {
     DEBUGLOG(5, "ZSTD_copyRawBlock");
-    if (dst == NULL) dstCapacity = 0;  /* better safe than sorry */
+    if (dst == NULL) {
+        if (srcSize == 0) return 0;
+        return ERROR(dstSize_tooSmall);
+    }
     if (srcSize > dstCapacity) return ERROR(dstSize_tooSmall);
     memcpy(dst, src, srcSize);
     return srcSize;
-- 
2.47.3