tests/component/updater_test.cpp

/*
 * Copyright (C) 2016 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 <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include <memory>
#include <string>
#include <vector>

#include <android-base/file.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <android-base/test_utils.h>
#include <bootloader_message/bootloader_message.h>
#include <bsdiff.h>
#include <gtest/gtest.h>
#include <ziparchive/zip_archive.h>
#include <ziparchive/zip_writer.h>

#include "common/test_constants.h"
#include "edify/expr.h"
#include "error_code.h"
#include "otautil/SysUtil.h"
#include "print_sha1.h"
#include "updater/blockimg.h"
#include "updater/install.h"
#include "updater/updater.h"

struct selabel_handle *sehandle = nullptr;

static void expect(const char* expected, const char* expr_str, CauseCode cause_code,
                   UpdaterInfo* info = nullptr) {
  std::unique_ptr<Expr> e;
  int error_count = 0;
  ASSERT_EQ(0, parse_string(expr_str, &e, &error_count));
  ASSERT_EQ(0, error_count);

  State state(expr_str, info);

  std::string result;
  bool status = Evaluate(&state, e, &result);

  if (expected == nullptr) {
    ASSERT_FALSE(status);
  } else {
    ASSERT_TRUE(status);
    ASSERT_STREQ(expected, result.c_str());
  }

  // Error code is set in updater/updater.cpp only, by parsing State.errmsg.
  ASSERT_EQ(kNoError, state.error_code);

  // Cause code should always be available.
  ASSERT_EQ(cause_code, state.cause_code);
}

static std::string get_sha1(const std::string& content) {
  uint8_t digest[SHA_DIGEST_LENGTH];
  SHA1(reinterpret_cast<const uint8_t*>(content.c_str()), content.size(), digest);
  return print_sha1(digest);
}

class UpdaterTest : public ::testing::Test {
 protected:
  virtual void SetUp() override {
    RegisterBuiltins();
    RegisterInstallFunctions();
    RegisterBlockImageFunctions();
  }
};

TEST_F(UpdaterTest, getprop) {
    expect(android::base::GetProperty("ro.product.device", "").c_str(),
           "getprop(\"ro.product.device\")",
           kNoCause);

    expect(android::base::GetProperty("ro.build.fingerprint", "").c_str(),
           "getprop(\"ro.build.fingerprint\")",
           kNoCause);

    // getprop() accepts only one parameter.
    expect(nullptr, "getprop()", kArgsParsingFailure);
    expect(nullptr, "getprop(\"arg1\", \"arg2\")", kArgsParsingFailure);
}

TEST_F(UpdaterTest, sha1_check) {
    // sha1_check(data) returns the SHA-1 of the data.
    expect("81fe8bfe87576c3ecb22426f8e57847382917acf", "sha1_check(\"abcd\")", kNoCause);
    expect("da39a3ee5e6b4b0d3255bfef95601890afd80709", "sha1_check(\"\")", kNoCause);

    // sha1_check(data, sha1_hex, [sha1_hex, ...]) returns the matched SHA-1.
    expect("81fe8bfe87576c3ecb22426f8e57847382917acf",
           "sha1_check(\"abcd\", \"81fe8bfe87576c3ecb22426f8e57847382917acf\")",
           kNoCause);

    expect("81fe8bfe87576c3ecb22426f8e57847382917acf",
           "sha1_check(\"abcd\", \"wrong_sha1\", \"81fe8bfe87576c3ecb22426f8e57847382917acf\")",
           kNoCause);

    // Or "" if there's no match.
    expect("",
           "sha1_check(\"abcd\", \"wrong_sha1\")",
           kNoCause);

    expect("",
           "sha1_check(\"abcd\", \"wrong_sha1\", \"wrong_sha2\")",
           kNoCause);

    // sha1_check() expects at least one argument.
    expect(nullptr, "sha1_check()", kArgsParsingFailure);
}

TEST_F(UpdaterTest, apply_patch_check) {
  // Zero-argument is not valid.
  expect(nullptr, "apply_patch_check()", kArgsParsingFailure);

  // File not found.
  expect("", "apply_patch_check(\"/doesntexist\")", kNoCause);

  std::string src_file = from_testdata_base("old.file");
  std::string src_content;
  ASSERT_TRUE(android::base::ReadFileToString(src_file, &src_content));
  size_t src_size = src_content.size();
  std::string src_hash = get_sha1(src_content);

  // One-argument with EMMC:file:size:sha1 should pass the check.
  std::string filename = android::base::Join(
      std::vector<std::string>{ "EMMC", src_file, std::to_string(src_size), src_hash }, ":");
  std::string cmd = "apply_patch_check(\"" + filename + "\")";
  expect("t", cmd.c_str(), kNoCause);

  // EMMC:file:(size-1):sha1:(size+1):sha1 should fail the check.
  std::string filename_bad = android::base::Join(
      std::vector<std::string>{ "EMMC", src_file, std::to_string(src_size - 1), src_hash,
                                std::to_string(src_size + 1), src_hash },
      ":");
  cmd = "apply_patch_check(\"" + filename_bad + "\")";
  expect("", cmd.c_str(), kNoCause);

  // EMMC:file:(size-1):sha1:size:sha1:(size+1):sha1 should pass the check.
  filename_bad =
      android::base::Join(std::vector<std::string>{ "EMMC", src_file, std::to_string(src_size - 1),
                                                    src_hash, std::to_string(src_size), src_hash,
                                                    std::to_string(src_size + 1), src_hash },
                          ":");
  cmd = "apply_patch_check(\"" + filename_bad + "\")";
  expect("t", cmd.c_str(), kNoCause);

  // Multiple arguments.
  cmd = "apply_patch_check(\"" + filename + "\", \"wrong_sha1\", \"wrong_sha2\")";
  expect("", cmd.c_str(), kNoCause);

  cmd = "apply_patch_check(\"" + filename + "\", \"wrong_sha1\", \"" + src_hash +
        "\", \"wrong_sha2\")";
  expect("t", cmd.c_str(), kNoCause);

  cmd = "apply_patch_check(\"" + filename_bad + "\", \"wrong_sha1\", \"" + src_hash +
        "\", \"wrong_sha2\")";
  expect("t", cmd.c_str(), kNoCause);
}

TEST_F(UpdaterTest, file_getprop) {
    // file_getprop() expects two arguments.
    expect(nullptr, "file_getprop()", kArgsParsingFailure);
    expect(nullptr, "file_getprop(\"arg1\")", kArgsParsingFailure);
    expect(nullptr, "file_getprop(\"arg1\", \"arg2\", \"arg3\")", kArgsParsingFailure);

    // File doesn't exist.
    expect(nullptr, "file_getprop(\"/doesntexist\", \"key1\")", kFileGetPropFailure);

    // Reject too large files (current limit = 65536).
    TemporaryFile temp_file1;
    std::string buffer(65540, '\0');
    ASSERT_TRUE(android::base::WriteStringToFile(buffer, temp_file1.path));

    // Read some keys.
    TemporaryFile temp_file2;
    std::string content("ro.product.name=tardis\n"
                        "# comment\n\n\n"
                        "ro.product.model\n"
                        "ro.product.board =  magic \n");
    ASSERT_TRUE(android::base::WriteStringToFile(content, temp_file2.path));

    std::string script1("file_getprop(\"" + std::string(temp_file2.path) +
                       "\", \"ro.product.name\")");
    expect("tardis", script1.c_str(), kNoCause);

    std::string script2("file_getprop(\"" + std::string(temp_file2.path) +
                       "\", \"ro.product.board\")");
    expect("magic", script2.c_str(), kNoCause);

    // No match.
    std::string script3("file_getprop(\"" + std::string(temp_file2.path) +
                       "\", \"ro.product.wrong\")");
    expect("", script3.c_str(), kNoCause);

    std::string script4("file_getprop(\"" + std::string(temp_file2.path) +
                       "\", \"ro.product.name=\")");
    expect("", script4.c_str(), kNoCause);

    std::string script5("file_getprop(\"" + std::string(temp_file2.path) +
                       "\", \"ro.product.nam\")");
    expect("", script5.c_str(), kNoCause);

    std::string script6("file_getprop(\"" + std::string(temp_file2.path) +
                       "\", \"ro.product.model\")");
    expect("", script6.c_str(), kNoCause);
}

// TODO: Test extracting to block device.
TEST_F(UpdaterTest, package_extract_file) {
  // package_extract_file expects 1 or 2 arguments.
  expect(nullptr, "package_extract_file()", kArgsParsingFailure);
  expect(nullptr, "package_extract_file(\"arg1\", \"arg2\", \"arg3\")", kArgsParsingFailure);

  std::string zip_path = from_testdata_base("ziptest_valid.zip");
  ZipArchiveHandle handle;
  ASSERT_EQ(0, OpenArchive(zip_path.c_str(), &handle));

  // Need to set up the ziphandle.
  UpdaterInfo updater_info;
  updater_info.package_zip = handle;

  // Two-argument version.
  TemporaryFile temp_file1;
  std::string script("package_extract_file(\"a.txt\", \"" + std::string(temp_file1.path) + "\")");
  expect("t", script.c_str(), kNoCause, &updater_info);

  // Verify the extracted entry.
  std::string data;
  ASSERT_TRUE(android::base::ReadFileToString(temp_file1.path, &data));
  ASSERT_EQ(kATxtContents, data);

  // Now extract another entry to the same location, which should overwrite.
  script = "package_extract_file(\"b.txt\", \"" + std::string(temp_file1.path) + "\")";
  expect("t", script.c_str(), kNoCause, &updater_info);

  ASSERT_TRUE(android::base::ReadFileToString(temp_file1.path, &data));
  ASSERT_EQ(kBTxtContents, data);

  // Missing zip entry. The two-argument version doesn't abort.
  script = "package_extract_file(\"doesntexist\", \"" + std::string(temp_file1.path) + "\")";
  expect("", script.c_str(), kNoCause, &updater_info);

  // Extract to /dev/full should fail.
  script = "package_extract_file(\"a.txt\", \"/dev/full\")";
  expect("", script.c_str(), kNoCause, &updater_info);

  // One-argument version.
  script = "sha1_check(package_extract_file(\"a.txt\"))";
  expect(kATxtSha1Sum.c_str(), script.c_str(), kNoCause, &updater_info);

  script = "sha1_check(package_extract_file(\"b.txt\"))";
  expect(kBTxtSha1Sum.c_str(), script.c_str(), kNoCause, &updater_info);

  // Missing entry. The one-argument version aborts the evaluation.
  script = "package_extract_file(\"doesntexist\")";
  expect(nullptr, script.c_str(), kPackageExtractFileFailure, &updater_info);

  CloseArchive(handle);
}

TEST_F(UpdaterTest, write_value) {
  // write_value() expects two arguments.
  expect(nullptr, "write_value()", kArgsParsingFailure);
  expect(nullptr, "write_value(\"arg1\")", kArgsParsingFailure);
  expect(nullptr, "write_value(\"arg1\", \"arg2\", \"arg3\")", kArgsParsingFailure);

  // filename cannot be empty.
  expect(nullptr, "write_value(\"value\", \"\")", kArgsParsingFailure);

  // Write some value to file.
  TemporaryFile temp_file;
  std::string value = "magicvalue";
  std::string script("write_value(\"" + value + "\", \"" + std::string(temp_file.path) + "\")");
  expect("t", script.c_str(), kNoCause);

  // Verify the content.
  std::string content;
  ASSERT_TRUE(android::base::ReadFileToString(temp_file.path, &content));
  ASSERT_EQ(value, content);

  // Allow writing empty string.
  script = "write_value(\"\", \"" + std::string(temp_file.path) + "\")";
  expect("t", script.c_str(), kNoCause);

  // Verify the content.
  ASSERT_TRUE(android::base::ReadFileToString(temp_file.path, &content));
  ASSERT_EQ("", content);

  // It should fail gracefully when write fails.
  script = "write_value(\"value\", \"/proc/0/file1\")";
  expect("", script.c_str(), kNoCause);
}

TEST_F(UpdaterTest, get_stage) {
  // get_stage() expects one argument.
  expect(nullptr, "get_stage()", kArgsParsingFailure);
  expect(nullptr, "get_stage(\"arg1\", \"arg2\")", kArgsParsingFailure);
  expect(nullptr, "get_stage(\"arg1\", \"arg2\", \"arg3\")", kArgsParsingFailure);

  // Set up a local file as BCB.
  TemporaryFile tf;
  std::string temp_file(tf.path);
  bootloader_message boot;
  strlcpy(boot.stage, "2/3", sizeof(boot.stage));
  std::string err;
  ASSERT_TRUE(write_bootloader_message_to(boot, temp_file, &err));

  // Can read the stage value.
  std::string script("get_stage(\"" + temp_file + "\")");
  expect("2/3", script.c_str(), kNoCause);

  // Bad BCB path.
  script = "get_stage(\"doesntexist\")";
  expect("", script.c_str(), kNoCause);
}

TEST_F(UpdaterTest, set_stage) {
  // set_stage() expects two arguments.
  expect(nullptr, "set_stage()", kArgsParsingFailure);
  expect(nullptr, "set_stage(\"arg1\")", kArgsParsingFailure);
  expect(nullptr, "set_stage(\"arg1\", \"arg2\", \"arg3\")", kArgsParsingFailure);

  // Set up a local file as BCB.
  TemporaryFile tf;
  std::string temp_file(tf.path);
  bootloader_message boot;
  strlcpy(boot.command, "command", sizeof(boot.command));
  strlcpy(boot.stage, "2/3", sizeof(boot.stage));
  std::string err;
  ASSERT_TRUE(write_bootloader_message_to(boot, temp_file, &err));

  // Write with set_stage().
  std::string script("set_stage(\"" + temp_file + "\", \"1/3\")");
  expect(tf.path, script.c_str(), kNoCause);

  // Verify.
  bootloader_message boot_verify;
  ASSERT_TRUE(read_bootloader_message_from(&boot_verify, temp_file, &err));

  // Stage should be updated, with command part untouched.
  ASSERT_STREQ("1/3", boot_verify.stage);
  ASSERT_STREQ(boot.command, boot_verify.command);

  // Bad BCB path.
  script = "set_stage(\"doesntexist\", \"1/3\")";
  expect("", script.c_str(), kNoCause);

  script = "set_stage(\"/dev/full\", \"1/3\")";
  expect("", script.c_str(), kNoCause);
}

TEST_F(UpdaterTest, set_progress) {
  // set_progress() expects one argument.
  expect(nullptr, "set_progress()", kArgsParsingFailure);
  expect(nullptr, "set_progress(\"arg1\", \"arg2\")", kArgsParsingFailure);

  // Invalid progress argument.
  expect(nullptr, "set_progress(\"arg1\")", kArgsParsingFailure);
  expect(nullptr, "set_progress(\"3x+5\")", kArgsParsingFailure);
  expect(nullptr, "set_progress(\".3.5\")", kArgsParsingFailure);

  TemporaryFile tf;
  UpdaterInfo updater_info;
  updater_info.cmd_pipe = fdopen(tf.fd, "w");
  expect(".52", "set_progress(\".52\")", kNoCause, &updater_info);
  fflush(updater_info.cmd_pipe);

  std::string cmd;
  ASSERT_TRUE(android::base::ReadFileToString(tf.path, &cmd));
  ASSERT_EQ(android::base::StringPrintf("set_progress %f\n", .52), cmd);
  // recovery-updater protocol expects 2 tokens ("set_progress <frac>").
  ASSERT_EQ(2U, android::base::Split(cmd, " ").size());
}

TEST_F(UpdaterTest, show_progress) {
  // show_progress() expects two arguments.
  expect(nullptr, "show_progress()", kArgsParsingFailure);
  expect(nullptr, "show_progress(\"arg1\")", kArgsParsingFailure);
  expect(nullptr, "show_progress(\"arg1\", \"arg2\", \"arg3\")", kArgsParsingFailure);

  // Invalid progress arguments.
  expect(nullptr, "show_progress(\"arg1\", \"arg2\")", kArgsParsingFailure);
  expect(nullptr, "show_progress(\"3x+5\", \"10\")", kArgsParsingFailure);
  expect(nullptr, "show_progress(\".3\", \"5a\")", kArgsParsingFailure);

  TemporaryFile tf;
  UpdaterInfo updater_info;
  updater_info.cmd_pipe = fdopen(tf.fd, "w");
  expect(".52", "show_progress(\".52\", \"10\")", kNoCause, &updater_info);
  fflush(updater_info.cmd_pipe);

  std::string cmd;
  ASSERT_TRUE(android::base::ReadFileToString(tf.path, &cmd));
  ASSERT_EQ(android::base::StringPrintf("progress %f %d\n", .52, 10), cmd);
  // recovery-updater protocol expects 3 tokens ("progress <frac> <secs>").
  ASSERT_EQ(3U, android::base::Split(cmd, " ").size());
}

TEST_F(UpdaterTest, block_image_update) {
  // Create a zip file with new_data and patch_data.
  TemporaryFile zip_file;
  FILE* zip_file_ptr = fdopen(zip_file.fd, "wb");
  ZipWriter zip_writer(zip_file_ptr);

  // Add a dummy new data.
  ASSERT_EQ(0, zip_writer.StartEntry("new_data", 0));
  ASSERT_EQ(0, zip_writer.FinishEntry());

  // Generate and add the patch data.
  std::string src_content = std::string(4096, 'a') + std::string(4096, 'c');
  std::string tgt_content = std::string(4096, 'b') + std::string(4096, 'd');
  TemporaryFile patch_file;
  ASSERT_EQ(0, bsdiff::bsdiff(reinterpret_cast<const uint8_t*>(src_content.data()),
      src_content.size(), reinterpret_cast<const uint8_t*>(tgt_content.data()),
      tgt_content.size(), patch_file.path, nullptr));
  std::string patch_content;
  ASSERT_TRUE(android::base::ReadFileToString(patch_file.path, &patch_content));
  ASSERT_EQ(0, zip_writer.StartEntry("patch_data", 0));
  ASSERT_EQ(0, zip_writer.WriteBytes(patch_content.data(), patch_content.size()));
  ASSERT_EQ(0, zip_writer.FinishEntry());

  // Add two transfer lists. The first one contains a bsdiff; and we expect the update to succeed.
  std::string src_hash = get_sha1(src_content);
  std::string tgt_hash = get_sha1(tgt_content);
  std::vector<std::string> transfer_list = {
    "4",
    "2",
    "0",
    "2",
    "stash " + src_hash + " 2,0,2",
    android::base::StringPrintf("bsdiff 0 %zu %s %s 2,0,2 2 - %s:2,0,2", patch_content.size(),
                                src_hash.c_str(), tgt_hash.c_str(), src_hash.c_str()),
    "free " + src_hash,
  };
  ASSERT_EQ(0, zip_writer.StartEntry("transfer_list", 0));
  std::string commands = android::base::Join(transfer_list, '\n');
  ASSERT_EQ(0, zip_writer.WriteBytes(commands.data(), commands.size()));
  ASSERT_EQ(0, zip_writer.FinishEntry());

  // Stash and free some blocks, then fail the 2nd update intentionally.
  std::vector<std::string> fail_transfer_list = {
    "4",
    "2",
    "0",
    "2",
    "stash " + tgt_hash + " 2,0,2",
    "free " + tgt_hash,
    "fail",
  };
  ASSERT_EQ(0, zip_writer.StartEntry("fail_transfer_list", 0));
  std::string fail_commands = android::base::Join(fail_transfer_list, '\n');
  ASSERT_EQ(0, zip_writer.WriteBytes(fail_commands.data(), fail_commands.size()));
  ASSERT_EQ(0, zip_writer.FinishEntry());
  ASSERT_EQ(0, zip_writer.Finish());
  ASSERT_EQ(0, fclose(zip_file_ptr));

  MemMapping map;
  ASSERT_TRUE(map.MapFile(zip_file.path));
  ZipArchiveHandle handle;
  ASSERT_EQ(0, OpenArchiveFromMemory(map.addr, map.length, zip_file.path, &handle));

  // Set up the handler, command_pipe, patch offset & length.
  UpdaterInfo updater_info;
  updater_info.package_zip = handle;
  TemporaryFile temp_pipe;
  updater_info.cmd_pipe = fopen(temp_pipe.path, "wb");
  updater_info.package_zip_addr = map.addr;
  updater_info.package_zip_len = map.length;

  // Execute the commands in the 1st transfer list.
  TemporaryFile update_file;
  ASSERT_TRUE(android::base::WriteStringToFile(src_content, update_file.path));
  std::string script = "block_image_update(\"" + std::string(update_file.path) +
      R"(", package_extract_file("transfer_list"), "new_data", "patch_data"))";
  expect("t", script.c_str(), kNoCause, &updater_info);
  // The update_file should be patched correctly.
  std::string updated_content;
  ASSERT_TRUE(android::base::ReadFileToString(update_file.path, &updated_content));
  ASSERT_EQ(tgt_hash, get_sha1(updated_content));

  // Expect the 2nd update to fail, but expect the stashed blocks to be freed.
  script = "block_image_update(\"" + std::string(update_file.path) +
      R"(", package_extract_file("fail_transfer_list"), "new_data", "patch_data"))";
  expect("", script.c_str(), kNoCause, &updater_info);
  // Updater generates the stash name based on the input file name.
  std::string name_digest = get_sha1(update_file.path);
  std::string stash_base = "/cache/recovery/" + name_digest;
  ASSERT_EQ(0, access(stash_base.c_str(), F_OK));
  ASSERT_EQ(-1, access((stash_base + tgt_hash).c_str(), F_OK));
  ASSERT_EQ(0, rmdir(stash_base.c_str()));

  ASSERT_EQ(0, fclose(updater_info.cmd_pipe));
  CloseArchive(handle);
}

TEST_F(UpdaterTest, new_data_short_write) {
  // Create a zip file with new_data.
  TemporaryFile zip_file;
  FILE* zip_file_ptr = fdopen(zip_file.fd, "wb");
  ZipWriter zip_writer(zip_file_ptr);

  // Add the empty new data.
  ASSERT_EQ(0, zip_writer.StartEntry("empty_new_data", 0));
  ASSERT_EQ(0, zip_writer.FinishEntry());
  // Add the short written new data.
  ASSERT_EQ(0, zip_writer.StartEntry("short_new_data", 0));
  std::string new_data_short = std::string(10, 'a');
  ASSERT_EQ(0, zip_writer.WriteBytes(new_data_short.data(), new_data_short.size()));
  ASSERT_EQ(0, zip_writer.FinishEntry());
  // Add the data of exactly one block.
  ASSERT_EQ(0, zip_writer.StartEntry("exact_new_data", 0));
  std::string new_data_exact = std::string(4096, 'a');
  ASSERT_EQ(0, zip_writer.WriteBytes(new_data_exact.data(), new_data_exact.size()));
  ASSERT_EQ(0, zip_writer.FinishEntry());
  // Add a dummy patch data.
  ASSERT_EQ(0, zip_writer.StartEntry("patch_data", 0));
  ASSERT_EQ(0, zip_writer.FinishEntry());

  std::vector<std::string> transfer_list = {
    "4",
    "1",
    "0",
    "0",
    "new 2,0,1",
  };
  ASSERT_EQ(0, zip_writer.StartEntry("transfer_list", 0));
  std::string commands = android::base::Join(transfer_list, '\n');
  ASSERT_EQ(0, zip_writer.WriteBytes(commands.data(), commands.size()));
  ASSERT_EQ(0, zip_writer.FinishEntry());
  ASSERT_EQ(0, zip_writer.Finish());
  ASSERT_EQ(0, fclose(zip_file_ptr));

  MemMapping map;
  ASSERT_TRUE(map.MapFile(zip_file.path));
  ZipArchiveHandle handle;
  ASSERT_EQ(0, OpenArchiveFromMemory(map.addr, map.length, zip_file.path, &handle));

  // Set up the handler, command_pipe, patch offset & length.
  UpdaterInfo updater_info;
  updater_info.package_zip = handle;
  TemporaryFile temp_pipe;
  updater_info.cmd_pipe = fopen(temp_pipe.path, "wb");
  updater_info.package_zip_addr = map.addr;
  updater_info.package_zip_len = map.length;

  // Updater should report the failure gracefully rather than stuck in deadlock.
  TemporaryFile update_file;
  std::string script_empty_data = "block_image_update(\"" + std::string(update_file.path) +
      R"(", package_extract_file("transfer_list"), "empty_new_data", "patch_data"))";
  expect("", script_empty_data.c_str(), kNoCause, &updater_info);

  std::string script_short_data = "block_image_update(\"" + std::string(update_file.path) +
      R"(", package_extract_file("transfer_list"), "short_new_data", "patch_data"))";
  expect("", script_short_data.c_str(), kNoCause, &updater_info);

  // Expect to write 1 block of new data successfully.
  std::string script_exact_data = "block_image_update(\"" + std::string(update_file.path) +
      R"(", package_extract_file("transfer_list"), "exact_new_data", "patch_data"))";
  expect("t", script_exact_data.c_str(), kNoCause, &updater_info);
}