Add basic tests for fileops functions

Summary:
Add basic tests for `folly::fileops::{open,read,write,close,pipe}`.

These are implemented for windows to handle sockets and /dev/null. They are simple aliases on non-windows.

Reviewed By: Orvid

Differential Revision: D66838378

fbshipit-source-id: feee6f1f14deebab58d928dc8b31d0012b7d834a

folly/portability/Unistd.h

@@ -103,6 +103,14 @@ namespace fileops {
 #ifdef _WIN32
 int close(int fh);
 ssize_t read(int fh, void* buf, size_t mcc);
+
+/// Create a pipe, returning the file descriptors in `pth`.
+///
+/// On windows this has different behavior than the traditional posix pipe.
+/// The returned file descriptors are unix sockets for compatibility with
+/// libevent. Also, they allow bidirectional reads and writes,
+/// unlike posix which only supports a single direction.
+/// @file
 int pipe(int pth[2]);
 ssize_t write(int fh, void const* buf, size_t count);
 #else

folly/portability/test/BUCK

@@ -1,3 +1,4 @@
+load("@fbcode//target_determinator/macros:ci.bzl", "ci")
 load("@fbcode_macros//build_defs:cpp_unittest.bzl", "cpp_unittest")
 
 oncall("fbcode_entropy_wardens_folly")
@@ -11,6 +12,18 @@ cpp_unittest(
     ],
 )
 
+cpp_unittest(
+    name = "fcntl_test",
+    srcs = ["FcntlTest.cpp"],
+    labels = ci.labels(
+        ci.windows(ci.mode("fbcode//mode/win")),
+    ),
+    deps = [
+        "//folly/portability:fcntl",
+        "//folly/portability:unistd",
+    ],
+)
+
 cpp_unittest(
     name = "filesystem_test",
     srcs = ["FilesystemTest.cpp"],
@@ -57,3 +70,14 @@ cpp_unittest(
         "//folly/test:test_utils",
     ],
 )
+
+cpp_unittest(
+    name = "unistd_test",
+    srcs = ["UnistdTest.cpp"],
+    labels = ci.labels(
+        ci.windows(ci.mode("fbcode//mode/win")),
+    ),
+    deps = [
+        "//folly/portability:unistd",
+    ],
+)

folly/portability/test/FcntlTest.cpp

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * 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 <folly/portability/Fcntl.h>
+#include <folly/portability/Unistd.h>
+
+#include <gtest/gtest.h>
+
+using namespace ::testing;
+
+/// Test that open supports "/dev/null" on Windows.
+///
+/// Windows doesn't have a /dev/null, but it does have
+/// NUL, which achieves the same result.
+TEST(FcntlTest, OpenDevNull) {
+  int fd = folly::fileops::open("/dev/null", O_RDWR);
+  ASSERT_GE(fd, 0);
+
+  ASSERT_EQ(3, folly::fileops::write(fd, "abc", 3));
+
+  {
+    char buf[4] = {1, 2, 3, 4};
+    // Reads from /dev/null always return 0 for end-of-file (EOF).
+    ASSERT_EQ(0, folly::fileops::read(fd, buf, 3));
+    ASSERT_EQ(buf[0], 1);
+    ASSERT_EQ(buf[1], 2);
+    ASSERT_EQ(buf[2], 3);
+    ASSERT_EQ(buf[3], 4);
+  }
+
+  ASSERT_EQ(0, folly::fileops::close(fd));
+}

folly/portability/test/UnistdTest.cpp

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * 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 <folly/portability/Unistd.h>
+
+#include <gtest/gtest.h>
+
+using namespace ::testing;
+
+/// Simple smoke test of `folly::fileops::{pipe, read, write, close}` functions.
+///
+/// On windows, the file descriptors created will be unix sockets, which is
+/// normally unsupported by the windows UCRT version of these functions.
+///
+/// This tests pipe's ability to perform a write, read, and close.
+TEST(UnistdTest, FileOpsSmokeTest) {
+  int fds[2] = {-1};
+  ASSERT_EQ(0, folly::fileops::pipe(fds));
+  int readEnd = fds[0];
+  int writeEnd = fds[1];
+  ASSERT_GE(readEnd, 0);
+  ASSERT_GE(writeEnd, 0);
+
+  ASSERT_EQ(4, folly::fileops::write(writeEnd, "pika", 4));
+
+  {
+    char actual[5] = {0};
+    ASSERT_EQ(4, folly::fileops::read(readEnd, actual, 4));
+    ASSERT_STREQ("pika", actual);
+  }
+
+  ASSERT_EQ(0, folly::fileops::close(readEnd));
+  ASSERT_EQ(0, folly::fileops::close(writeEnd));
+}