Atmosphere/libraries/libstratosphere/source/fs/fs_sd_card.cpp

/*
 * Copyright (c) 2018-2020 Atmosphère-NX
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <stratosphere.hpp>
#include "fsa/fs_mount_utils.hpp"

namespace ams::fs {

    namespace {

        /* NOTE: Nintendo does not attach a generator to a mounted SD card filesystem. */
        /* However, it is desirable for homebrew to be able to access SD via common path. */
        class SdCardCommonMountNameGenerator : public fsa::ICommonMountNameGenerator, public impl::Newable {
            public:
                explicit SdCardCommonMountNameGenerator() { /* ... */ }

                virtual Result GenerateCommonMountName(char *dst, size_t dst_size) override {
                    /* Determine how much space we need. */
                    const size_t needed_size = strnlen(impl::SdCardFileSystemMountName, MountNameLengthMax) + 2;
                    AMS_ABORT_UNLESS(dst_size >= needed_size);

                    /* Generate the name. */
                    auto size = std::snprintf(dst, dst_size, "%s:", impl::SdCardFileSystemMountName);
                    AMS_ASSERT(static_cast<size_t>(size) == needed_size - 1);

                    return ResultSuccess();
                }
        };

    }


    Result MountSdCard(const char *name) {
        /* Validate the mount name. */
        R_TRY(impl::CheckMountName(name));

        /* Open the SD card. This uses libnx bindings. */
        FsFileSystem fs;
        R_TRY(fsOpenSdCardFileSystem(std::addressof(fs)));

        /* Allocate a new filesystem wrapper. */
        auto fsa = std::make_unique<RemoteFileSystem>(fs);
        R_UNLESS(fsa != nullptr, fs::ResultAllocationFailureInSdCardA());

        /* Allocate a new mountname generator. */
        /* NOTE: Nintendo does not attach a generator. */
        auto generator = std::make_unique<SdCardCommonMountNameGenerator>();
        R_UNLESS(generator != nullptr, fs::ResultAllocationFailureInSdCardA());

        /* Register. */
        return fsa::Register(name, std::move(fsa), std::move(generator));
    }

}