Merge "Fix precompiled sepolicy logic"

    }

    // Use precompiled sepolicy only when all corresponding hashes are equal.

    // plat_sepolicy is always checked, while system_ext and product are checked only when they

    // exist.

    std::vector<std::pair<std::string, std::string>> sepolicy_hashes{

            {"/system/etc/selinux/plat_sepolicy_and_mapping.sha256",

             precompiled_sepolicy + ".plat_sepolicy_and_mapping.sha256"},

            {"/system_ext/etc/selinux/system_ext_sepolicy_and_mapping.sha256",

             precompiled_sepolicy + ".system_ext_sepolicy_and_mapping.sha256"},

            {"/product/etc/selinux/product_sepolicy_and_mapping.sha256",

             precompiled_sepolicy + ".product_sepolicy_and_mapping.sha256"},

    };

    if (access("/system_ext/etc/selinux/system_ext_sepolicy.cil", F_OK) == 0) {

        sepolicy_hashes.emplace_back(

                "/system_ext/etc/selinux/system_ext_sepolicy_and_mapping.sha256",

                precompiled_sepolicy + ".system_ext_sepolicy_and_mapping.sha256");

    for (const auto& [actual_id_path, precompiled_id_path] : sepolicy_hashes) {

        // Both of them should exist or both of them shouldn't exist.

        if (access(actual_id_path.c_str(), R_OK) != 0) {

            if (access(precompiled_id_path.c_str(), R_OK) == 0) {

                return Error() << precompiled_id_path << " exists but " << actual_id_path

                               << " doesn't";

            }

    if (access("/product/etc/selinux/product_sepolicy.cil", F_OK) == 0) {

        sepolicy_hashes.emplace_back("/product/etc/selinux/product_sepolicy_and_mapping.sha256",

                                     precompiled_sepolicy + ".product_sepolicy_and_mapping.sha256");

            continue;

        }

    for (const auto& [actual_id_path, precompiled_id_path] : sepolicy_hashes) {

        std::string actual_id;

        if (!ReadFirstLine(actual_id_path.c_str(), &actual_id)) {

            return ErrnoError() << "Failed to read " << actual_id_path;