1 files changed, 32 insertions, 10 deletions
diff --git a/src/filesystem/operations.cpp b/src/filesystem/operations.cpp
index b41061888724..69350ddfe9da 100644
--- a/src/filesystem/operations.cpp
+++ b/src/filesystem/operations.cpp
@@ -1,9 +1,8 @@
 //===--------------------- filesystem/ops.cpp -----------------------------===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
@@ -45,6 +44,10 @@
 #include <sys/time.h> // for gettimeofday and timeval
 #endif                // !defined(CLOCK_REALTIME)
 
+#if defined(__unix__) &&  defined(__ELF__) && defined(_LIBCPP_HAS_COMMENT_LIB_PRAGMA)
+#pragma comment(lib, "rt")
+#endif
+
 #if defined(_LIBCPP_COMPILER_GCC)
 #if _GNUC_VER < 500
 #pragma GCC diagnostic ignored "-Wmissing-field-initializers"
@@ -543,11 +546,19 @@ path __canonical(path const& orig_p, error_code* ec) {
   ErrorHandler<path> err("canonical", ec, &orig_p, &cwd);
 
   path p = __do_absolute(orig_p, &cwd, ec);
+#if _POSIX_VERSION >= 200112
+  std::unique_ptr<char, decltype(&::free)>
+    hold(::realpath(p.c_str(), nullptr), &::free);
+  if (hold.get() == nullptr)
+    return err.report(capture_errno());
+  return {hold.get()};
+#else
   char buff[PATH_MAX + 1];
   char* ret;
   if ((ret = ::realpath(p.c_str(), buff)) == nullptr)
     return err.report(capture_errno());
   return {ret};
+#endif
 }
 
 void __copy(const path& from, const path& to, copy_options options,
@@ -1089,16 +1100,27 @@ void __permissions(const path& p, perms prms, perm_options opts,
 path __read_symlink(const path& p, error_code* ec) {
   ErrorHandler<path> err("read_symlink", ec, &p);
 
-  char buff[PATH_MAX + 1];
-  error_code m_ec;
-  ::ssize_t ret;
-  if ((ret = ::readlink(p.c_str(), buff, PATH_MAX)) == -1) {
+#ifdef PATH_MAX
+  struct NullDeleter { void operator()(void*) const {} };
+  const size_t size = PATH_MAX + 1;
+  char stack_buff[size];
+  auto buff = std::unique_ptr<char[], NullDeleter>(stack_buff);
+#else
+  StatT sb;
+  if (::lstat(p.c_str(), &sb) == -1) {
     return err.report(capture_errno());
   }
-  _LIBCPP_ASSERT(ret <= PATH_MAX, "TODO");
+  const size_t size = sb.st_size + 1;
+  auto buff = unique_ptr<char[]>(new char[size]);
+#endif
+  ::ssize_t ret;
+  if ((ret = ::readlink(p.c_str(), buff.get(), size)) == -1)
+    return err.report(capture_errno());
   _LIBCPP_ASSERT(ret > 0, "TODO");
+  if (static_cast<size_t>(ret) >= size)
+    return err.report(errc::value_too_large);
   buff[ret] = 0;
-  return {buff};
+  return {buff.get()};
 }
 
 bool __remove(const path& p, error_code* ec) {