From d7666083a7ccae0e5238137303480b3229510232 Mon Sep 17 00:00:00 2001
From: Victor Dyachenko <vdyachenko3@bloomberg.net>
Date: Mon, 13 May 2024 09:55:51 -0400
Subject: [PATCH] Prevent memcpy(nullptr, ..., 0) call (#4736)

---
 groups/bdl/bdlbb/bdlbb_blobstreambuf.cpp | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/groups/bdl/bdlbb/bdlbb_blobstreambuf.cpp b/groups/bdl/bdlbb/bdlbb_blobstreambuf.cpp
index 1231cac318..be2b67b7a8 100644
--- a/groups/bdl/bdlbb/bdlbb_blobstreambuf.cpp
+++ b/groups/bdl/bdlbb/bdlbb_blobstreambuf.cpp
@@ -556,10 +556,13 @@ bsl::streamsize OutBlobStreamBuf::xsputn(const char_type *source,
         bsl::streamsize remainingChars = epptr() - pptr();
         bsl::streamsize canCopy        = bsl::min(remainingChars, numLeft);
 
-        bsl::memcpy(pptr(), source + numCopied, canCopy);
-        pbump(static_cast<int>(canCopy));
-        numCopied += canCopy;
-        numLeft -= canCopy;
+        if (canCopy > 0) {
+            BSLS_ASSERT(pptr());
+            bsl::memcpy(pptr(), source + numCopied, canCopy);
+            pbump(static_cast<int>(canCopy));
+            numCopied += canCopy;
+            numLeft -= canCopy;
+        }
 
         if (0 < numLeft) {
             if (traits_type::eof() ==