Otapreopt: Filter preopted system apps

#define TOKEN_MAX     16    /* max number of arguments in buffer */

#define REPLY_MAX     256   /* largest reply allowed */

using android::base::EndsWith;

using android::base::Join;

using android::base::Split;

using android::base::StartsWith;

using android::base::StringPrintf;

namespace android {

    }

    int RunPreopt() {

        // Run the preopt.

        //

        // There's one thing we have to be careful about: we may/will be asked to compile an app

        // living in the system image. This may be a valid request - if the app wasn't compiled,

        // e.g., if the system image wasn't large enough to include preopted files. However, the

        // data we have is from the old system, so the driver (the OTA service) can't actually

        // know. Thus, we will get requests for apps that have preopted components. To avoid

        // duplication (we'd generate files that are not used and are *not* cleaned up), do two

        // simple checks:

        //

        // 1) Does the apk_path start with the value of ANDROID_ROOT? (~in the system image)

        //    (For simplicity, assume the value of ANDROID_ROOT does not contain a symlink.)

        //

        // 2) If you replace the name in the apk_path with "oat," does the path exist?

        //    (=have a subdirectory for preopted files)

        //

        // If the answer to both is yes, skip the dexopt.

        //

        // Note: while one may think it's OK to call dexopt and it will fail (because APKs should

        //       be stripped), that's not true for APKs signed outside the build system (so the

        //       jar content must be exactly the same).

        //       (This is ugly as it's the only thing where we need to understand the contents

        //        of package_parameters_, but it beats postponing the decision or using the call-

        //        backs to do weird things.)

        constexpr size_t kApkPathIndex = 0;

        CHECK_GT(DEXOPT_PARAM_COUNT, kApkPathIndex);

        CHECK(package_parameters_[kApkPathIndex] != nullptr);

        CHECK(system_properties_.GetProperty(kAndroidRootPathPropertyName) != nullptr);

        if (StartsWith(package_parameters_[kApkPathIndex],

                       system_properties_.GetProperty(kAndroidRootPathPropertyName)->c_str())) {

            const char* last_slash = strrchr(package_parameters_[kApkPathIndex], '/');

            if (last_slash != nullptr) {

                std::string path(package_parameters_[kApkPathIndex],

                                 last_slash - package_parameters_[kApkPathIndex] + 1);

                CHECK(EndsWith(path, "/"));

                path = path + "oat";

                if (access(path.c_str(), F_OK) == 0) {

                    return 0;

                }

            }

        }

        return dexopt(package_parameters_);

    }