[singlejar] Add port library for various MSVC hacks

A small `port` library with various MSVC hacks. This is needed for future PRs.

For non-Windows platforms, `port.cc` will produce an empty object file.

#2241 /cc @laszlocsomor

Closes #5501.

PiperOrigin-RevId: 204889516

3 files changed, 104 insertions, 0 deletions

diff --git a/src/tools/singlejar/BUILD b/src/tools/singlejar/BUILD
index a855a22064..5c1da1ff21 100644
--- a/src/tools/singlejar/BUILD
+++ b/src/tools/singlejar/BUILD
@@ -31,6 +31,8 @@ filegroup(
         "options.h",
         "output_jar.cc",
         "output_jar.h",
+        "port.cc",
+        "port.h",
         "singlejar_main.cc",
         "token_stream.h",
         "transient_bytes.h",
@@ -345,6 +347,13 @@ cc_library(
 )
 
 cc_library(
+    name = "port",
+    srcs = ["port.cc"],
+    hdrs = ["port.h"],
+    visibility = ["//visibility:private"],
+)
+
+cc_library(
     name = "mapped_file",
     srcs = select({
         "//src:windows": ["mapped_file_windows.inc"],
diff --git a/src/tools/singlejar/port.cc b/src/tools/singlejar/port.cc
new file mode 100644
index 0000000000..298eea173e
--- /dev/null
+++ b/src/tools/singlejar/port.cc
@@ -0,0 +1,40 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifdef _WIN32
+
+#include "src/tools/singlejar/port.h"
+
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#include <windows.h>
+
+ssize_t pread(int fd, void *buf, size_t count, off64_t offset) {
+  DWORD ret = -1;
+  HANDLE hFile = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
+  if (hFile) {
+    OVERLAPPED overlap;
+    memset(&overlap, 0, sizeof(OVERLAPPED));
+    overlap.Offset = offset;
+    if (!::ReadFile(hFile, buf, count, &ret, &overlap)) {
+      // For this simple implementation, we don't update errno.
+      // Just return -1 as error.
+      return -1;
+    }
+  }
+  return ret;
+}
+
+#endif  // _WIN32
diff --git a/src/tools/singlejar/port.h b/src/tools/singlejar/port.h
new file mode 100644
index 0000000000..8d244602d0
--- /dev/null
+++ b/src/tools/singlejar/port.h
@@ -0,0 +1,55 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef BAZEL_SRC_TOOLS_SINGLEJAR_PORT_H_
+#define BAZEL_SRC_TOOLS_SINGLEJAR_PORT_H_ 1
+
+#ifdef _WIN32
+// This macro is required to tell MSVC headers to also define POSIX names
+// without "_" prefix (such as "open" for "_open").
+#define _CRT_DECLARE_NONSTDC_NAMES 1
+#include <fcntl.h>
+#include <io.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <time.h>
+
+#ifdef _WIN64
+// MSVC by default defines stat and related functions to a version with 32-bit
+// st_size even for Win64. We want 64-bit st_size instead so that we can handle
+// large file.
+#undef stat
+#undef fstat
+#define stat _stat64
+#define fstat _fstat64
+#endif  // _WIN64
+
+typedef ptrdiff ssize_t;
+
+// Various MSVC polyfills for POSIX functions.
+
+inline tm* localtime_r(const time_t* tin, tm* tout) {
+  if (!localtime_s(tout, tin)) return tout;
+
+  return nullptr;
+}
+
+// Make sure that the file HANDLE associated with |fd| is created by CreateFile
+// with FILE_FLAG_OVERLAPPED flag for this function to work.
+ssize_t pread(int fd, void* buf, size_t count, off64_t offset);
+
+#endif  // _WIN32
+
+#endif  //   BAZEL_SRC_TOOLS_SINGLEJAR_PORT_H_