[runtime] Add implementation of _swift_strlcpy

This safer function is missing on Linux.

Author: AnnaZaks

include/swift/Runtime/Portability.h

@@ -0,0 +1,23 @@
+//===--- Portability.h -----------------------------------------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// Includes stub APIs that make the portable runtime easier to write.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_RUNTIME_PORTABILITY_H
+#define SWIFT_RUNTIME_PORTABILITY_H
+#include <stddef.h>
+
+size_t _swift_strlcpy(char *dst, const char *src, size_t maxlen);
+
+#endif

stdlib/public/runtime/CMakeLists.txt

@@ -47,6 +47,7 @@ set(swift_runtime_sources
     MetadataLookup.cpp
     Mutex.cpp
     Once.cpp
+    Portability.cpp
     ProtocolConformance.cpp
     Reflection.cpp
     RuntimeEntrySymbols.cpp

stdlib/public/runtime/Portability.cpp

@@ -0,0 +1,29 @@
+//===--- Portability.cpp - -----------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===---------------------------------------------------------------------===//
+//
+// Implementations of the stub APIs that make portable runtime easier to write.
+//
+//===---------------------------------------------------------------------===//
+
+#include "swift/Runtime/Portability.h"
+#include <cstring>
+
+size_t _swift_strlcpy(char *dst, const char *src, size_t maxlen) {
+  const size_t srclen = std::strlen(src);
+  if (srclen < maxlen) {
+    std::memmove(dst, src, srclen + 1);
+  } else if (maxlen != 0) {
+    std::memmove(dst, src, maxlen - 1);
+    dst[maxlen - 1] = '\0';
+  }
+  return srclen;
+}

stdlib/public/runtime/Reflection.mm

@@ -17,6 +17,7 @@
 #include "swift/Runtime/Enum.h"
 #include "swift/Basic/Demangle.h"
 #include "swift/Runtime/Debug.h"
+#include "swift/Runtime/Portability.h"
 #include "Private.h"
 #include <cassert>
 #include <cstdio>
@@ -1247,6 +1248,6 @@ static Mirror ObjC_getMirrorForSuperclass(Class sup,
   }
 
   // Copy into the provided buffer.
-  strlcpy(outputBuffer, result.c_str(), *outputBufferSize);
+  _swift_strlcpy(outputBuffer, result.c_str(), *outputBufferSize);
   return outputBuffer;
 }