Components/IFS/src/include/IFS/FWFS/FileSystem.h

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/****
 * FileSystem.h
 * FWFS - Firmware File System
 *
 * Created on: 19 Jul 2018
 *
 * Copyright 2019 mikee47 <mike@sillyhouse.net>
 *
 * This file is part of the IFS Library
 *
 * This library is free software: you can redistribute it and/or modify it under the terms of the
 * GNU General Public License as published by the Free Software Foundation, version 3 or later.
 *
 * This library is distributed in the hope that 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 library.
 * If not, see <https://www.gnu.org/licenses/>.
 *
 ****/

#pragma once

#include "../IFileSystem.h"
#include "Object.h"

namespace IFS
{
namespace FWFS
{
// File handles start at this value
#ifndef FWFS_HANDLE_MIN
#define FWFS_HANDLE_MIN 100
#endif

// Maximum number of file descriptors
#ifndef FWFS_MAX_FDS
#define FWFS_MAX_FDS 8
#endif

// Maximum number of volumes - 1 is minimum, the rest are mounted in subdirectories
#ifndef FWFS_MAX_VOLUMES
#define FWFS_MAX_VOLUMES 4
#endif

// Maximum file handle value
#define FWFS_HANDLE_MAX (FWFS_HANDLE_MIN + FWFS_MAX_FDS - 1)

struct FWFileDesc {
    FWObjDesc odFile; 
    union {
        struct {
            uint32_t dataSize; 
            uint32_t cursor;   
        };
        // For MountPoint
        struct {
            IFileSystem* fileSystem;
            union {
                FileHandle file;
                DirHandle dir;
            };
        };
    };

    bool isAllocated() const
    {
        return odFile.obj.typeData != 0;
    }

    bool isMountPoint() const
    {
        return odFile.obj.isMountPoint();
    }

    void reset()
    {
        *this = FWFileDesc{};
    }
};

struct FWVolume {
    std::unique_ptr<IFileSystem> fileSystem;
};

class FileSystem : public IFileSystem
{
public:
    FileSystem(Storage::Partition partition) : partition(partition)
    {
    }

    // IFileSystem methods
    int mount() override;
    int getinfo(Info& info) override;
    String getErrorString(int err) override;
    int setVolume(uint8_t index, IFileSystem* fileSystem) override;
    int opendir(const char* path, DirHandle& dir) override;
    int readdir(DirHandle dir, Stat& stat) override;
    int rewinddir(DirHandle dir) override;
    int closedir(DirHandle dir) override;
    int mkdir(const char* path) override;
    int stat(const char* path, Stat* stat) override;
    int fstat(FileHandle file, Stat* stat) override;
    int fcontrol(FileHandle file, ControlCode code, void* buffer, size_t bufSize) override;
    int fsetxattr(FileHandle file, AttributeTag tag, const void* data, size_t size) override;
    int fgetxattr(FileHandle file, AttributeTag tag, void* buffer, size_t size) override;
    int fenumxattr(FileHandle file, AttributeEnumCallback callback, void* buffer, size_t bufsize) override;
    int setxattr(const char* path, AttributeTag tag, const void* data, size_t size) override;
    int getxattr(const char* path, AttributeTag tag, void* buffer, size_t size) override;
    FileHandle open(const char* path, OpenFlags flags) override;
    int close(FileHandle file) override;
    int read(FileHandle file, void* data, size_t size) override;
    int write(FileHandle file, const void* data, size_t size) override;
    file_offset_t lseek(FileHandle file, file_offset_t offset, SeekOrigin origin) override;
    int eof(FileHandle file) override;
    file_offset_t tell(FileHandle file) override;
    int ftruncate(FileHandle file, file_size_t new_size) override;
    int flush(FileHandle file) override;
    int fgetextents(FileHandle file, Storage::Partition* part, Extent* list, uint16_t extcount) override;
    int rename(const char* oldpath, const char* newpath) override;
    int remove(const char* path) override;
    int fremove(FileHandle file) override;
    int format() override
    {
        return Error::ReadOnly;
    }
    int check() override
    {
        /* We could implement this, but since problems would indicate corrupted firmware
         * there isn't much we can do other than suggest a re-flashing. This sort of issue
         * is better resolved externally using a hash of the entire firmware image. */
        return Error::NotImplemented;
    }

private:
    int getMd5Hash(FWFileDesc& fd, void* buffer, size_t bufSize);

    bool isMounted()
    {
        return flags[Flag::mounted];
    }

    int readObjectHeader(FWObjDesc& od);

    int getChildObject(const FWObjDesc& parent, const FWObjDesc& child, FWObjDesc& od);

    int readChildObjectHeader(const FWObjDesc& parent, FWObjDesc& child);

    int readObjectContent(const FWObjDesc& od, uint32_t offset, uint32_t size, void* buffer);

    int findUnusedDescriptor();

    int findChildObjectHeader(const FWObjDesc& parent, FWObjDesc& child, Object::Type objId);
    int findChildObject(const FWObjDesc& parent, FWObjDesc& child, const char* name, unsigned namelen);
    int findObject(Object::ID objId, FWObjDesc& od);

    int findObjectByPath(const char*& path, FWObjDesc& od);

    int resolveMountPoint(const FWObjDesc& odMountPoint, IFileSystem*& fileSystem);

    /*
     * @brief Resolve path to mounted volume.
     * @param path Path to parse, consumes path to mount point
     * @param fileSystem Located filesystem
     * @retval int error code
     * 
     * Used for methods which require write access are read-only unless path corresponds to mounted volume.
     * If path is within this volume then Error::ReadOnly is returned.
     */
    int findLinkedObject(const char*& path, IFileSystem*& fileSystem);

    int getObjectDataSize(FWObjDesc& od, uint32_t& dataSize);

    int readObjectName(const FWObjDesc& od, NameBuffer& name);
    int fillStat(Stat& stat, const FWObjDesc& entry);
    int readAttribute(FWObjDesc& od, AttributeTag tag, void* buffer, size_t size);

    void printObject(const FWObjDesc& od, bool isChild);

protected:
    enum class Flag {
        mounted,
    };

    Storage::Partition partition;
    FWVolume volumes[FWFS_MAX_VOLUMES]; 
    FWFileDesc fileDescriptors[FWFS_MAX_FDS];
    FWObjDesc odRoot; 
    Object::ID volume;
    ACL rootACL{};
    BitSet<uint8_t, Flag> flags;
};

} // namespace FWFS

} // namespace IFS