Clean up the 32-bit kernel support, fix LP64 fcntl declaration.

In practice, thanks to all the registers the stubs don't actually change,
but it's confusing to have an incorrect declaration.

I suspect that fcntl remains broken for aarch64; it happens to work for
x86_64 because the first vararg argument gets placed in the right register
anyway, but I have no reason to believe that's true for aarch64.

This patch adds a unit test, though, so we'll be able to tell when we get
as far as running the unit tests.

Change-Id: I58dd0054fe99d7d51d04c22781d8965dff1afbf3

tests/fcntl_test.cpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2013 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 <gtest/gtest.h>
+
+#include <errno.h>
+#include <fcntl.h>
+
+TEST(fcntl, fcntl_smoke) {
+  int fd = open("/proc/version", O_RDONLY);
+  ASSERT_TRUE(fd != -1);
+
+  int flags = fcntl(fd, F_GETFD);
+  ASSERT_TRUE(flags != -1);
+  ASSERT_EQ(0, flags & FD_CLOEXEC);
+
+  int rc = fcntl(fd, F_SETFD, FD_CLOEXEC);
+  ASSERT_EQ(0, rc);
+
+  flags = fcntl(fd, F_GETFD);
+  ASSERT_TRUE(flags != -1);
+  ASSERT_EQ(FD_CLOEXEC, flags & FD_CLOEXEC);
+}