Merge commit '73630d5e20c8' from llvm.org/main into next

Author: git apple-llvm automerger

llvm/lib/Support/raw_socket_stream.cpp

@@ -119,6 +119,14 @@ ListeningSocket::ListeningSocket(ListeningSocket &&LS)
 Expected<ListeningSocket> ListeningSocket::createUnix(StringRef SocketPath,
                                                       int MaxBacklog) {
 
+  // If SocketPath is too long, the path will be truncated, and there may be
+  // collisions with other truncated addresses that the fs::exists check below
+  // will be unable to detect.
+  if (SocketPath.size() >= sizeof(sockaddr_un::sun_path))
+    return llvm::make_error<StringError>(
+        std::make_error_code(std::errc::filename_too_long),
+        "SocketPath too long");
+
   // Handle instances where the target socket address already exists and
   // differentiate between a preexisting file with and without a bound socket
   //