1 files changed, 61 insertions, 0 deletions
diff --git a/test/syscalls/linux/getrandom.cc b/test/syscalls/linux/getrandom.cc
new file mode 100644
index 000000000..be5325497
--- /dev/null
+++ b/test/syscalls/linux/getrandom.cc
@@ -0,0 +1,61 @@
+// 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 <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "gtest/gtest.h"
+#include "test/util/test_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+#ifndef SYS_getrandom
+#if defined(__x86_64__)
+#define SYS_getrandom 318
+#elif defined(__i386__)
+#define SYS_getrandom 355
+#else
+#error "Unknown architecture"
+#endif
+#endif  // SYS_getrandom
+
+bool SomeByteIsNonZero(char* random_bytes, int length) {
+  for (int i = 0; i < length; i++) {
+    if (random_bytes[i] != 0) {
+      return true;
+    }
+  }
+  return false;
+}
+
+TEST(GetrandomTest, IsRandom) {
+  // This test calls get_random and makes sure that the array is filled in with
+  // something that is non-zero. Perhaps we get back \x00\x00\x00\x00\x00.... as
+  // a random result, but it's so unlikely that we'll just ignore this.
+  char random_bytes[64] = {};
+  int n = syscall(SYS_getrandom, random_bytes, 64, 0);
+  SKIP_IF(!IsRunningOnGvisor() && n < 0 && errno == ENOSYS);
+  EXPECT_THAT(n, SyscallSucceeds());
+  EXPECT_GT(n, 0);  // Some bytes should be returned.
+  EXPECT_TRUE(SomeByteIsNonZero(random_bytes, n));
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor