1 files changed, 142 insertions, 0 deletions
diff --git a/test/syscalls/linux/madvise.cc b/test/syscalls/linux/madvise.cc
new file mode 100644
index 000000000..a79c8c75d
--- /dev/null
+++ b/test/syscalls/linux/madvise.cc
@@ -0,0 +1,142 @@
+// Copyright 2018 Google LLC
+//
+// 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 <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <string>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "gtest/gtest.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/logging.h"
+#include "test/util/memory_util.h"
+#include "test/util/posix_error.h"
+#include "test/util/temp_path.h"
+#include "test/util/test_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+void ExpectAllMappingBytes(Mapping const& m, char c) {
+  auto const v = m.view();
+  for (size_t i = 0; i < kPageSize; i++) {
+    ASSERT_EQ(v[i], c) << "at offset " << i;
+  }
+}
+
+// Equivalent to ExpectAllMappingBytes but async-signal-safe and with less
+// helpful failure messages.
+void CheckAllMappingBytes(Mapping const& m, char c) {
+  auto const v = m.view();
+  for (size_t i = 0; i < kPageSize; i++) {
+    TEST_CHECK_MSG(v[i] == c, "mapping contains wrong value");
+  }
+}
+
+TEST(MadviseDontneedTest, ZerosPrivateAnonPage) {
+  auto m = ASSERT_NO_ERRNO_AND_VALUE(
+      MmapAnon(kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE));
+  ExpectAllMappingBytes(m, 0);
+  memset(m.ptr(), 1, m.len());
+  ExpectAllMappingBytes(m, 1);
+  ASSERT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
+  ExpectAllMappingBytes(m, 0);
+}
+
+TEST(MadviseDontneedTest, ZerosCOWAnonPageInCallerOnly) {
+  auto m = ASSERT_NO_ERRNO_AND_VALUE(
+      MmapAnon(kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE));
+  ExpectAllMappingBytes(m, 0);
+  memset(m.ptr(), 2, m.len());
+  ExpectAllMappingBytes(m, 2);
+
+  // Do madvise in a child process.
+  pid_t pid = fork();
+  CheckAllMappingBytes(m, 2);
+  if (pid == 0) {
+    TEST_PCHECK(madvise(m.ptr(), m.len(), MADV_DONTNEED) == 0);
+    CheckAllMappingBytes(m, 0);
+    _exit(0);
+  }
+
+  ASSERT_THAT(pid, SyscallSucceeds());
+
+  int status = 0;
+  ASSERT_THAT(waitpid(-1, &status, 0), SyscallSucceedsWithValue(pid));
+  EXPECT_TRUE(WIFEXITED(status));
+  EXPECT_EQ(WEXITSTATUS(status), 0);
+  // The child's madvise should not have affected the parent.
+  ExpectAllMappingBytes(m, 2);
+}
+
+TEST(MadviseDontneedTest, DoesNotModifySharedAnonPage) {
+  auto m = ASSERT_NO_ERRNO_AND_VALUE(
+      MmapAnon(kPageSize, PROT_READ | PROT_WRITE, MAP_SHARED));
+  ExpectAllMappingBytes(m, 0);
+  memset(m.ptr(), 3, m.len());
+  ExpectAllMappingBytes(m, 3);
+  ASSERT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
+  ExpectAllMappingBytes(m, 3);
+}
+
+TEST(MadviseDontneedTest, CleansPrivateFilePage) {
+  TempPath f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
+      /* parent = */ GetAbsoluteTestTmpdir(),
+      /* content = */ std::string(kPageSize, 4), TempPath::kDefaultFileMode));
+  FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDWR));
+
+  Mapping m = ASSERT_NO_ERRNO_AND_VALUE(Mmap(
+      nullptr, kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd.get(), 0));
+  ExpectAllMappingBytes(m, 4);
+  memset(m.ptr(), 5, m.len());
+  ExpectAllMappingBytes(m, 5);
+  ASSERT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
+  ExpectAllMappingBytes(m, 4);
+}
+
+TEST(MadviseDontneedTest, DoesNotModifySharedFilePage) {
+  TempPath f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
+      /* parent = */ GetAbsoluteTestTmpdir(),
+      /* content = */ std::string(kPageSize, 6), TempPath::kDefaultFileMode));
+  FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDWR));
+
+  Mapping m = ASSERT_NO_ERRNO_AND_VALUE(Mmap(
+      nullptr, kPageSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd.get(), 0));
+  ExpectAllMappingBytes(m, 6);
+  memset(m.ptr(), 7, m.len());
+  ExpectAllMappingBytes(m, 7);
+  ASSERT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
+  ExpectAllMappingBytes(m, 7);
+}
+
+TEST(MadviseDontneedTest, IgnoresPermissions) {
+  auto m =
+      ASSERT_NO_ERRNO_AND_VALUE(MmapAnon(kPageSize, PROT_NONE, MAP_PRIVATE));
+  EXPECT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor