- add runtime/platform/unistd.h for Windows x64 compatibility

- fix extension/data_loader/file_data_loader.cpp for Windows x64

Author: Yi Ren

extension/data_loader/file_data_loader.cpp

@@ -17,7 +17,7 @@
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
-#include <unistd.h>
+#include <executorch/runtime/platform/unistd.h>
 
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/result.h>
@@ -26,9 +26,9 @@
 // Some platforms (e.g. Xtensa) do not support pread() that we use to read the
 // file at different offsets simultaneously from multiple threads not affecting
 // each other. We list them below and use a workaround for them.
-#if defined(__xtensa__)
+#if defined(__xtensa__) || defined(_WIN64)
 #define ET_HAVE_PREAD 0
-#endif // defined(__xtensa__)
+#endif // defined(__xtensa__) || defined(_WIN64)
 
 #ifndef ET_HAVE_PREAD
 #define ET_HAVE_PREAD 1
@@ -71,6 +71,9 @@ FileDataLoader::~FileDataLoader() {
   std::free(const_cast<char*>(file_name_));
   // fd_ can be -1 if this instance was moved from, but closing a negative fd is
   // safe (though it will return an error).
+  if (fd_ == -1) {
+    return;
+  }
   ::close(fd_);
 }
 

runtime/platform/unistd.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+/**
+ * @file
+ * unistd.h related macros for POSIX/Windows compatibility.
+ */
+#pragma once
+
+#if defined(_WIN32) && !defined(_WIN64)
+#error "You're trying to build ExecuTorch with a too old version of Windows. We need Windows 64-bit."
+#endif
+
+#if !defined(_WIN64)
+#include <unistd.h>
+#else
+#include <io.h>
+#define O_RDONLY _O_RDONLY
+#define open _open
+#define close _close
+#define read _read
+#define write _write
+#define stat _stat64
+#define fstat _fstat64
+#define off_t _off_t
+#define lseek _lseeki64
+
+#endif // !defined(_WIN64)