Stub out readahead implementation.

Closes #261

PiperOrigin-RevId: 270973347

3 files changed, 110 insertions, 0 deletions

diff --git a/test/syscalls/BUILD b/test/syscalls/BUILD
index 63e4c63dd..341e6b252 100644
--- a/test/syscalls/BUILD
+++ b/test/syscalls/BUILD
@@ -346,6 +346,11 @@ syscall_test(
 )
 
 syscall_test(
+    add_overlay = True,
+    test = "//test/syscalls/linux:readahead_test",
+)
+
+syscall_test(
     size = "medium",
     shard_count = 5,
     test = "//test/syscalls/linux:readv_socket_test",
diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index a4cebf46f..28b23ce58 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -1736,6 +1736,20 @@ cc_binary(
 )
 
 cc_binary(
+    name = "readahead_test",
+    testonly = 1,
+    srcs = ["readahead.cc"],
+    linkstatic = 1,
+    deps = [
+        "//test/util:file_descriptor",
+        "//test/util:temp_path",
+        "//test/util:test_main",
+        "//test/util:test_util",
+        "@com_google_googletest//:gtest",
+    ],
+)
+
+cc_binary(
     name = "readv_test",
     testonly = 1,
     srcs = [
diff --git a/test/syscalls/linux/readahead.cc b/test/syscalls/linux/readahead.cc
new file mode 100644
index 000000000..09703b5c1
--- /dev/null
+++ b/test/syscalls/linux/readahead.cc
@@ -0,0 +1,91 @@
+// Copyright 2019 The gVisor Authors.
+//
+// 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 <errno.h>
+#include <fcntl.h>
+
+#include "gtest/gtest.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/temp_path.h"
+#include "test/util/test_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+TEST(ReadaheadTest, InvalidFD) {
+  EXPECT_THAT(readahead(-1, 1, 1), SyscallFailsWithErrno(EBADF));
+}
+
+TEST(ReadaheadTest, InvalidOffset) {
+  const TempPath in_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(in_file.path(), O_RDWR));
+  EXPECT_THAT(readahead(fd.get(), -1, 1), SyscallFailsWithErrno(EINVAL));
+}
+
+TEST(ReadaheadTest, ValidOffset) {
+  constexpr char kData[] = "123";
+  const TempPath in_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
+      GetAbsoluteTestTmpdir(), kData, TempPath::kDefaultFileMode));
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(in_file.path(), O_RDWR));
+
+  // N.B. The implementation of readahead is filesystem-specific, and a file
+  // backed by ram may return EINVAL because there is nothing to be read.
+  EXPECT_THAT(readahead(fd.get(), 1, 1), AnyOf(SyscallSucceedsWithValue(0),
+                                               SyscallFailsWithErrno(EINVAL)));
+}
+
+TEST(ReadaheadTest, PastEnd) {
+  constexpr char kData[] = "123";
+  const TempPath in_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
+      GetAbsoluteTestTmpdir(), kData, TempPath::kDefaultFileMode));
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(in_file.path(), O_RDWR));
+  // See above.
+  EXPECT_THAT(readahead(fd.get(), 2, 2), AnyOf(SyscallSucceedsWithValue(0),
+                                               SyscallFailsWithErrno(EINVAL)));
+}
+
+TEST(ReadaheadTest, CrossesEnd) {
+  constexpr char kData[] = "123";
+  const TempPath in_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
+      GetAbsoluteTestTmpdir(), kData, TempPath::kDefaultFileMode));
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(in_file.path(), O_RDWR));
+  // See above.
+  EXPECT_THAT(readahead(fd.get(), 4, 2), AnyOf(SyscallSucceedsWithValue(0),
+                                               SyscallFailsWithErrno(EINVAL)));
+}
+
+TEST(ReadaheadTest, WriteOnly) {
+  const TempPath in_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(in_file.path(), O_WRONLY));
+  EXPECT_THAT(readahead(fd.get(), 0, 1), SyscallFailsWithErrno(EBADF));
+}
+
+TEST(ReadaheadTest, InvalidSize) {
+  const TempPath in_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(in_file.path(), O_RDWR));
+  EXPECT_THAT(readahead(fd.get(), 0, -1), SyscallFailsWithErrno(EINVAL));
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor