Add an internal struct layout test.

A downstream user of bionic has a test that requires the sizes and
offsets of various fields in pthread_internal_t to be consistent
between x86 and arm32, and between x86_64 and arm64, by checking that
the sizes and offsets match hardcoded constants. Since this test often
makes it difficult to update bionic's internal data structures, add
a test to bionic that does the same thing so that we can remove the
downstream test and make it easier to change internal data structures
in bionic.

Change-Id: Id5bd3f9fae00aa3b50d1b1267e782e26fe6c8369
diff --git a/tests/struct_layout_test.cpp b/tests/struct_layout_test.cpp
new file mode 100644
index 0000000..9da702c
--- /dev/null
+++ b/tests/struct_layout_test.cpp
@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2020 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 <stdio.h>
+
+#if defined(__BIONIC__)
+#include "bionic/pthread_internal.h"
+
+// Ensure that the layout of these data structures is architecture independent and only depends on
+// the bitness of the architecture.
+template <typename CheckSize, typename CheckOffset>
+void tests(CheckSize check_size, CheckOffset check_offset) {
+#define CHECK_SIZE(name, size) \
+    check_size(#name, sizeof(name), size);
+#define CHECK_OFFSET(name, field, offset) \
+    check_offset(#name, #field, offsetof(name, field), offset);
+#ifdef __LP64__
+  CHECK_SIZE(pthread_internal_t, 768);
+  CHECK_OFFSET(pthread_internal_t, next, 0);
+  CHECK_OFFSET(pthread_internal_t, prev, 8);
+  CHECK_OFFSET(pthread_internal_t, tid, 16);
+  CHECK_OFFSET(pthread_internal_t, attr, 24);
+  CHECK_OFFSET(pthread_internal_t, join_state, 80);
+  CHECK_OFFSET(pthread_internal_t, cleanup_stack, 88);
+  CHECK_OFFSET(pthread_internal_t, start_routine, 96);
+  CHECK_OFFSET(pthread_internal_t, start_routine_arg, 104);
+  CHECK_OFFSET(pthread_internal_t, return_value, 112);
+  CHECK_OFFSET(pthread_internal_t, start_mask, 120);
+  CHECK_OFFSET(pthread_internal_t, alternate_signal_stack, 128);
+  CHECK_OFFSET(pthread_internal_t, shadow_call_stack_guard_region, 136);
+  CHECK_OFFSET(pthread_internal_t, stack_top, 144);
+  CHECK_OFFSET(pthread_internal_t, startup_handshake_lock, 152);
+  CHECK_OFFSET(pthread_internal_t, mmap_base, 160);
+  CHECK_OFFSET(pthread_internal_t, mmap_size, 168);
+  CHECK_OFFSET(pthread_internal_t, mmap_base_unguarded, 176);
+  CHECK_OFFSET(pthread_internal_t, mmap_size_unguarded, 184);
+  CHECK_OFFSET(pthread_internal_t, vma_name_buffer, 192);
+  CHECK_OFFSET(pthread_internal_t, thread_local_dtors, 224);
+  CHECK_OFFSET(pthread_internal_t, current_dlerror, 232);
+  CHECK_OFFSET(pthread_internal_t, dlerror_buffer, 240);
+  CHECK_OFFSET(pthread_internal_t, bionic_tls, 752);
+  CHECK_OFFSET(pthread_internal_t, errno_value, 760);
+  CHECK_SIZE(bionic_tls, 12200);
+  CHECK_OFFSET(bionic_tls, key_data, 0);
+  CHECK_OFFSET(bionic_tls, locale, 2080);
+  CHECK_OFFSET(bionic_tls, basename_buf, 2088);
+  CHECK_OFFSET(bionic_tls, dirname_buf, 6184);
+  CHECK_OFFSET(bionic_tls, mntent_buf, 10280);
+  CHECK_OFFSET(bionic_tls, mntent_strings, 10320);
+  CHECK_OFFSET(bionic_tls, ptsname_buf, 11344);
+  CHECK_OFFSET(bionic_tls, ttyname_buf, 11376);
+  CHECK_OFFSET(bionic_tls, strerror_buf, 11440);
+  CHECK_OFFSET(bionic_tls, strsignal_buf, 11695);
+  CHECK_OFFSET(bionic_tls, group, 11952);
+  CHECK_OFFSET(bionic_tls, passwd, 12040);
+  CHECK_OFFSET(bionic_tls, fdtrack_disabled, 12192);
+  CHECK_OFFSET(bionic_tls, padding, 12193);
+#else
+  CHECK_SIZE(pthread_internal_t, 664);
+  CHECK_OFFSET(pthread_internal_t, next, 0);
+  CHECK_OFFSET(pthread_internal_t, prev, 4);
+  CHECK_OFFSET(pthread_internal_t, tid, 8);
+  CHECK_OFFSET(pthread_internal_t, attr, 16);
+  CHECK_OFFSET(pthread_internal_t, join_state, 40);
+  CHECK_OFFSET(pthread_internal_t, cleanup_stack, 44);
+  CHECK_OFFSET(pthread_internal_t, start_routine, 48);
+  CHECK_OFFSET(pthread_internal_t, start_routine_arg, 52);
+  CHECK_OFFSET(pthread_internal_t, return_value, 56);
+  CHECK_OFFSET(pthread_internal_t, start_mask, 60);
+  CHECK_OFFSET(pthread_internal_t, alternate_signal_stack, 68);
+  CHECK_OFFSET(pthread_internal_t, shadow_call_stack_guard_region, 72);
+  CHECK_OFFSET(pthread_internal_t, stack_top, 76);
+  CHECK_OFFSET(pthread_internal_t, startup_handshake_lock, 80);
+  CHECK_OFFSET(pthread_internal_t, mmap_base, 88);
+  CHECK_OFFSET(pthread_internal_t, mmap_size, 92);
+  CHECK_OFFSET(pthread_internal_t, mmap_base_unguarded, 96);
+  CHECK_OFFSET(pthread_internal_t, mmap_size_unguarded, 100);
+  CHECK_OFFSET(pthread_internal_t, vma_name_buffer, 104);
+  CHECK_OFFSET(pthread_internal_t, thread_local_dtors, 136);
+  CHECK_OFFSET(pthread_internal_t, current_dlerror, 140);
+  CHECK_OFFSET(pthread_internal_t, dlerror_buffer, 144);
+  CHECK_OFFSET(pthread_internal_t, bionic_tls, 656);
+  CHECK_OFFSET(pthread_internal_t, errno_value, 660);
+  CHECK_SIZE(bionic_tls, 11080);
+  CHECK_OFFSET(bionic_tls, key_data, 0);
+  CHECK_OFFSET(bionic_tls, locale, 1040);
+  CHECK_OFFSET(bionic_tls, basename_buf, 1044);
+  CHECK_OFFSET(bionic_tls, dirname_buf, 5140);
+  CHECK_OFFSET(bionic_tls, mntent_buf, 9236);
+  CHECK_OFFSET(bionic_tls, mntent_strings, 9260);
+  CHECK_OFFSET(bionic_tls, ptsname_buf, 10284);
+  CHECK_OFFSET(bionic_tls, ttyname_buf, 10316);
+  CHECK_OFFSET(bionic_tls, strerror_buf, 10380);
+  CHECK_OFFSET(bionic_tls, strsignal_buf, 10635);
+  CHECK_OFFSET(bionic_tls, group, 10892);
+  CHECK_OFFSET(bionic_tls, passwd, 10952);
+  CHECK_OFFSET(bionic_tls, fdtrack_disabled, 11076);
+  CHECK_OFFSET(bionic_tls, padding, 11077);
+#endif  // __LP64__
+#undef CHECK_SIZE
+#undef CHECK_OFFSET
+}
+#endif  // defined(__BIONIC__)
+
+TEST(struct_layout, sizes_offsets) {
+#if defined(__BIONIC__)
+  bool failed = false;
+
+  auto check_size = [&](const char* name, size_t size, size_t expected_size) {
+    EXPECT_EQ(expected_size, size) << "sizeof(" << name << ")";
+    if (size != expected_size) {
+      failed = true;
+    }
+  };
+  auto check_offset = [&](const char* name, const char* field, size_t offset,
+                          size_t expected_offset) {
+    EXPECT_EQ(expected_offset, offset) << "offsetof(" << name << ", " << field << ")";
+    if (offset != expected_offset) {
+      failed = true;
+    }
+  };
+  tests(check_size, check_offset);
+
+  if (failed) {
+    printf(
+        "Please update the tests function in bionic/tests/struct_layout_test.cpp with the "
+        "following contents:\n");
+
+    auto print_size = [&](const char* name, size_t size, size_t expected_size) {
+      (void)expected_size;
+      printf("  CHECK_SIZE(%s, %zu);\n", name, size);
+    };
+    auto print_offset = [&](const char* name, const char* field, size_t offset,
+                            size_t expected_offset) {
+      (void)expected_offset;
+      printf("  CHECK_OFFSET(%s, %s, %zu);\n", name, field, offset);
+    };
+    tests(print_size, print_offset);
+  }
+#else
+  GTEST_SKIP() << "bionic-only test";
+#endif
+}