AAPT2: Fix windows unicode path issues

Mingw64 was being difficult, so instead of defining a wmain entrypoint,
the command line parameters are parsed manually using built-in Windows
methods that support Unicode. The results are converted to UTF8 and
handled just like the rest of the linux/mac version of the code.

This also removes dependencies on std::istream in favour of a
FileInputStream which calls the appropriate unicode version of
open to read a file.

No speed regressions found on Linux or MacOS.

Bug: 62336414
Bug: 63830502
Test: manual
Change-Id: I597da51e33729ed1b98bf246e7e773337fd3fee8
diff --git a/tools/aapt2/io/FileInputStream_test.cpp b/tools/aapt2/io/FileInputStream_test.cpp
new file mode 100644
index 0000000..7314ab7
--- /dev/null
+++ b/tools/aapt2/io/FileInputStream_test.cpp
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include "io/FileInputStream.h"
+
+#include "android-base/macros.h"
+#include "android-base/test_utils.h"
+
+#include "test/Test.h"
+
+using ::android::StringPiece;
+using ::testing::Eq;
+using ::testing::NotNull;
+using ::testing::StrEq;
+
+namespace aapt {
+namespace io {
+
+TEST(FileInputStreamTest, NextAndBackup) {
+  std::string input = "this is a cool string";
+  TemporaryFile file;
+  ASSERT_THAT(TEMP_FAILURE_RETRY(write(file.fd, input.c_str(), input.size())), Eq(21));
+  lseek64(file.fd, 0, SEEK_SET);
+
+  // Use a small buffer size so that we can call Next() a few times.
+  FileInputStream in(file.fd, 10u);
+  ASSERT_FALSE(in.HadError());
+  EXPECT_THAT(in.ByteCount(), Eq(0u));
+
+  const char* buffer;
+  size_t size;
+  ASSERT_TRUE(in.Next(reinterpret_cast<const void**>(&buffer), &size)) << in.GetError();
+  ASSERT_THAT(size, Eq(10u));
+  ASSERT_THAT(buffer, NotNull());
+  EXPECT_THAT(in.ByteCount(), Eq(10u));
+  EXPECT_THAT(StringPiece(buffer, size), Eq("this is a "));
+
+  ASSERT_TRUE(in.Next(reinterpret_cast<const void**>(&buffer), &size));
+  ASSERT_THAT(size, Eq(10u));
+  ASSERT_THAT(buffer, NotNull());
+  EXPECT_THAT(in.ByteCount(), Eq(20u));
+  EXPECT_THAT(StringPiece(buffer, size), Eq("cool strin"));
+
+  in.BackUp(5u);
+  EXPECT_THAT(in.ByteCount(), Eq(15u));
+
+  ASSERT_TRUE(in.Next(reinterpret_cast<const void**>(&buffer), &size));
+  ASSERT_THAT(size, Eq(5u));
+  ASSERT_THAT(buffer, NotNull());
+  ASSERT_THAT(in.ByteCount(), Eq(20u));
+  EXPECT_THAT(StringPiece(buffer, size), Eq("strin"));
+
+  // Backup 1 more than possible. Should clamp.
+  in.BackUp(11u);
+  EXPECT_THAT(in.ByteCount(), Eq(10u));
+
+  ASSERT_TRUE(in.Next(reinterpret_cast<const void**>(&buffer), &size));
+  ASSERT_THAT(size, Eq(10u));
+  ASSERT_THAT(buffer, NotNull());
+  ASSERT_THAT(in.ByteCount(), Eq(20u));
+  EXPECT_THAT(StringPiece(buffer, size), Eq("cool strin"));
+
+  ASSERT_TRUE(in.Next(reinterpret_cast<const void**>(&buffer), &size));
+  ASSERT_THAT(size, Eq(1u));
+  ASSERT_THAT(buffer, NotNull());
+  ASSERT_THAT(in.ByteCount(), Eq(21u));
+  EXPECT_THAT(StringPiece(buffer, size), Eq("g"));
+
+  EXPECT_FALSE(in.Next(reinterpret_cast<const void**>(&buffer), &size));
+  EXPECT_FALSE(in.HadError());
+}
+
+}  // namespace io
+}  // namespace aapt