android OTA package packing and extract to partition

android OTA package packing and extract to partition

1. 打包image并将写image到对应partition的命令写入OTA升级脚本里

device/google/dragon/releasetools.py

def FullOTA_InstallEnd(info):
  # copy the data into the package.
  try:
    bootloader_img = info.input_zip.read("RADIO/bootloader.img")
    ec_img = info.input_zip.read("RADIO/ec.bin")
  except KeyError:
    print "no firmware images in target_files; skipping install"
    return
  # copy the data into the package.
  common.ZipWriteStr(info.output_zip, "bootloader.img", bootloader_img) #应该是将bootloader.img打包到OTA package
  common.ZipWriteStr(info.output_zip, "ec.bin", ec_img)

  # emit the script code to trigger the firmware updater on the device
  info.script.AppendExtra(
    """dragon.firmware_update(package_extract_file("bootloader.img"), package_extract_file("ec.bin"));""")

build/tools/releasetools/edify_generator.py

  def AppendExtra(self, extra):
    """Append text verbatim to the output script."""
    self.script.append(extra)

self.script.append()应该是将package_extract_file命令写入一个OTA升级脚本里，这个脚本最终的样子类似于：
https://www.cnblogs.com/aspirs/p/13060333.html
在升级OTA package会执行这个命令将文件写入partition

build/tools/releasetools/edify_generator.py

  def WriteRawImage(self, mount_point, fn, mapfn=None):
    """Write the given package file into the partition for the given
    mount point."""

    fstab = self.fstab
    if fstab:
      p = fstab[mount_point]
      partition_type = common.PARTITION_TYPES[p.fs_type]
      args = {'device': p.device, 'fn': fn}
      if partition_type == "EMMC":
        if mapfn:
          args["map"] = mapfn
          self.script.append(
              'package_extract_file("%(fn)s", "%(device)s", "%(map)s");' % args)
        else:
          self.script.append(
              'package_extract_file("%(fn)s", "%(device)s");' % args)
      else:
        raise ValueError(
            "don't know how to write "%s" partitions" % p.fs_type)

2. 将image写到partition

bootable/recovery/updater/install.cpp

Value* PackageExtractFileFn(const char* name, State* state,
                            const std::vector<std::unique_ptr<Expr>>& argv) {
  if (argv.size() < 1 || argv.size() > 2) {
    return ErrorAbort(state, kArgsParsingFailure, "%s() expects 1 or 2 args, got %zu", name,
                      argv.size());
  }

  if (argv.size() == 2) {
    // The two-argument version extracts to a file.

    std::vector<std::string> args;
    if (!ReadArgs(state, argv, &args)) {
      return ErrorAbort(state, kArgsParsingFailure, "%s() Failed to parse %zu args", name,
                        argv.size());
    }
    const std::string& zip_path = args[0]; //bin name
    const std::string& dest_path = args[1]; //device name

    ZipArchiveHandle za = static_cast<UpdaterInfo*>(state->cookie)->package_zip;
    ZipString zip_string_path(zip_path.c_str());
    ZipEntry entry;
    if (FindEntry(za, zip_string_path, &entry) != 0) {
      LOG(ERROR) << name << ": no " << zip_path << " in package";
      return StringValue("");
    }

    unique_fd fd(TEMP_FAILURE_RETRY(
        ota_open(dest_path.c_str(), O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR)));
    if (fd == -1) {
      PLOG(ERROR) << name << ": can't open " << dest_path << " for write";
      return StringValue("");
    }

    bool success = true;
    int32_t ret = ExtractEntryToFile(za, &entry, fd); //fd是device name对应的fd，从zip package za里抽取bin name对应的entry写到fd（device name）
    if (ret != 0) {
      LOG(ERROR) << name << ": Failed to extract entry "" << zip_path << "" ("
                 << entry.uncompressed_length << " bytes) to "" << dest_path
                 << "": " << ErrorCodeString(ret);
      success = false;
    }
    if (ota_fsync(fd) == -1) {
      PLOG(ERROR) << "fsync of "" << dest_path << "" failed";
      success = false;
    }
    if (ota_close(fd) == -1) {
      PLOG(ERROR) << "close of "" << dest_path << "" failed";
      success = false;
    }

    return StringValue(success ? "t" : "");
  } else {
    // The one-argument version returns the contents of the file as the result.

    std::vector<std::string> args;
    if (!ReadArgs(state, argv, &args)) {
      return ErrorAbort(state, kArgsParsingFailure, "%s() Failed to parse %zu args", name,
                        argv.size());
    }
    const std::string& zip_path = args[0];

    ZipArchiveHandle za = static_cast<UpdaterInfo*>(state->cookie)->package_zip;
    ZipString zip_string_path(zip_path.c_str());
    ZipEntry entry;
    if (FindEntry(za, zip_string_path, &entry) != 0) {
      return ErrorAbort(state, kPackageExtractFileFailure, "%s(): no %s in package", name,
                        zip_path.c_str());
    }

    std::string buffer;
    buffer.resize(entry.uncompressed_length);

    int32_t ret =
        ExtractToMemory(za, &entry, reinterpret_cast<uint8_t*>(&buffer[0]), buffer.size());
    if (ret != 0) {
      return ErrorAbort(state, kPackageExtractFileFailure,
                        "%s: Failed to extract entry "%s" (%zu bytes) to memory: %s", name,
                        zip_path.c_str(), buffer.size(), ErrorCodeString(ret));
    }

    return new Value(VAL_BLOB, buffer);
  }
}

bootable/recovery/updater/install.cpp

void RegisterInstallFunctions() {
  RegisterFunction("mount", MountFn);
  RegisterFunction("is_mounted", IsMountedFn);
  RegisterFunction("unmount", UnmountFn);
  RegisterFunction("format", FormatFn);
  RegisterFunction("show_progress", ShowProgressFn);
  RegisterFunction("set_progress", SetProgressFn);
  RegisterFunction("package_extract_file", PackageExtractFileFn);

  RegisterFunction("getprop", GetPropFn);
  RegisterFunction("file_getprop", FileGetPropFn);

  RegisterFunction("apply_patch", ApplyPatchFn);
  RegisterFunction("apply_patch_check", ApplyPatchCheckFn);
  RegisterFunction("apply_patch_space", ApplyPatchSpaceFn);

  RegisterFunction("wipe_block_device", WipeBlockDeviceFn);

  RegisterFunction("read_file", ReadFileFn);
  RegisterFunction("sha1_check", Sha1CheckFn);
  RegisterFunction("write_value", WriteValueFn);

  RegisterFunction("wipe_cache", WipeCacheFn);

  RegisterFunction("ui_print", UIPrintFn);

  RegisterFunction("run_program", RunProgramFn);

  RegisterFunction("reboot_now", RebootNowFn);
  RegisterFunction("get_stage", GetStageFn);
  RegisterFunction("set_stage", SetStageFn);

  RegisterFunction("enable_reboot", EnableRebootFn);
  RegisterFunction("tune2fs", Tune2FsFn);
}