Add a host tool to pack R_ARM_RELATIVE relocations in libchrome.<ver>.so.

tools/relocation_packer/src/relocation_packer_elf_file_unittest.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Set to 1 to enable the dummy test that dumps test data to /tmp.
+#define DEBUG_TEST_DATA 0
+
+#include "relocation_packer_elf_file.h"
+
+#include <stdio.h>
+#include <vector>
+#include "relocation_packer_debug.h"
+#include "relocation_packer_elf_file_unittest_relocs.so.h"
+#include "relocation_packer_elf_file_unittest_relocs_golden.so.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+FILE* MaterializeRelocsTestFile(unsigned char* data, size_t length) {
+  FILE* temporary = tmpfile();
+  if (temporary)
+    fwrite(data, 1, length, temporary);
+  return temporary;
+}
+
+bool MaterializeRelocsTestFiles(FILE** relocs_so, FILE** packed_relocs_so) {
+  *relocs_so = MaterializeRelocsTestFile(
+      relocation_packer_elf_file_unittest_relocs_so,
+      relocation_packer_elf_file_unittest_relocs_so_len);
+
+  *packed_relocs_so = MaterializeRelocsTestFile(
+      relocation_packer_elf_file_unittest_relocs_golden_so,
+      relocation_packer_elf_file_unittest_relocs_golden_so_len);
+
+  return *relocs_so && *packed_relocs_so;

[rmcilroy, 2014/06/02 15:16:35]

Couldn't you just include these both as binary files in a data directory rather
than have them expressed as a header file?

[simonb (inactive), 2014/06/04 16:40:35]

Done.

+}
+
+void DematerializeRelocsTestFile(FILE* temporary) {
+  fclose(temporary);

[rmcilroy, 2014/06/02 15:16:35]

delete the temp files?

[simonb (inactive), 2014/06/04 16:40:35]

No need.  From tmpfile(1): "The file will be automatically deleted when it is
closed or the program terminates."  These files have no visible directory
entries.

+}
+
+void DematerializeRelocsTestFiles(FILE* relocs_so, FILE* packed_relocs_so) {
+  DematerializeRelocsTestFile(relocs_so);
+  DematerializeRelocsTestFile(packed_relocs_so);
+}
+
+bool FileContentsEqual(FILE* first, FILE* second) {
+  if (fseek(first, 0, SEEK_SET) || fseek(second, 0, SEEK_SET))
+    return false;
+
+  static const size_t buffer_size = 4096;
+  unsigned char first_buffer[buffer_size];
+  unsigned char second_buffer[buffer_size];
+
+  do {
+    size_t first_read = fread(first_buffer, 1, sizeof(first_buffer), first);
+    size_t second_read = fread(second_buffer, 1, sizeof(second_buffer), second);
+
+    if (first_read != second_read)
+      return false;
+    if (memcmp(first_buffer, second_buffer, first_read))
+      return false;
+  } while (!feof(first) && !feof(second));
+
+  return feof(first) && feof(second);
+}
+
+}  // namespace
+
+namespace relocation_packer {
+
+#if DEBUG_TEST_DATA

[rmcilroy, 2014/06/02 15:16:35]

This is never defined - can we just remove this test now?

[simonb (inactive), 2014/06/04 16:40:35]

Done.

+TEST(ElfFile, ExtractTestData) {
+  // Dummy test to dump data files to /tmp for debugging, always passes.
+  FILE* stream = fopen("/tmp/relocs.so", "wb");
+  if (stream) {
+    fwrite(relocation_packer_elf_file_unittest_relocs_so,
+           relocation_packer_elf_file_unittest_relocs_so_len,
+           1,
+           stream);
+    fclose(stream);
+  }
+
+  stream = fopen("/tmp/packed_relocs.so", "wb");
+  if (stream) {
+    fwrite(relocation_packer_elf_file_unittest_relocs_golden_so,
+           relocation_packer_elf_file_unittest_relocs_golden_so_len,
+           1,
+           stream);
+    fclose(stream);
+  }
+}
+#endif
+
+TEST(ElfFile, PackRelocations) {
+  ASSERT_NE(EV_NONE, elf_version(EV_CURRENT));
+
+  FILE* relocs_so = NULL;
+  FILE* packed_relocs_so = NULL;
+  ASSERT_TRUE(MaterializeRelocsTestFiles(&relocs_so, &packed_relocs_so));
+  ASSERT_FALSE(FileContentsEqual(relocs_so, packed_relocs_so));
+
+  ASSERT_EQ(0, lseek(fileno(relocs_so), 0, SEEK_SET));

[rmcilroy, 2014/06/02 15:16:35]

How about doing the lseek at the end of FileContentsEqual so that
FileContentsEqual is idempotent? Also, any reason it's not fseek?

[simonb (inactive), 2014/06/04 16:40:35]

Can't call ASSERT_EQ from a namespace-local function (because it returns a
value).

+
+  ElfFile elf_file;
+  EXPECT_TRUE(elf_file.Load(fileno(relocs_so)));
+
+  // Ensure unpacking fails (not packed).
+  EXPECT_FALSE(elf_file.UnpackRelocations());
+
+  // Pack relocations.
+  EXPECT_TRUE(elf_file.PackRelocations());
+  elf_file.Flush();
+
+  // Compare packed relocations to golden.
+  EXPECT_TRUE(FileContentsEqual(relocs_so, packed_relocs_so));
+
+  DematerializeRelocsTestFiles(relocs_so, packed_relocs_so);
+}
+
+TEST(ElfFile, UnpackRelocations) {
+  ASSERT_NE(EV_NONE, elf_version(EV_CURRENT));
+
+  FILE* relocs_so = NULL;
+  FILE* packed_relocs_so = NULL;
+  ASSERT_TRUE(MaterializeRelocsTestFiles(&relocs_so, &packed_relocs_so));
+  ASSERT_FALSE(FileContentsEqual(relocs_so, packed_relocs_so));
+
+  ASSERT_EQ(0, lseek(fileno(packed_relocs_so), 0, SEEK_SET));
+
+  ElfFile elf_file;
+  EXPECT_TRUE(elf_file.Load(fileno(packed_relocs_so)));
+
+  // Ensure packing fails (already packed).
+  EXPECT_FALSE(elf_file.PackRelocations());
+
+  // Unpack golden relocations.
+  EXPECT_TRUE(elf_file.UnpackRelocations());
+  elf_file.Flush();
+
+  // Compare unpacked relocations to originals.
+  EXPECT_TRUE(FileContentsEqual(packed_relocs_so, relocs_so));
+
+  DematerializeRelocsTestFiles(relocs_so, packed_relocs_so);
+}
+
+}  // namespace relocation_packer