Luna/kernel/src/fs/devices/DeviceRegistry.cpp

#include "fs/devices/DeviceRegistry.h"
#include "Log.h"
#include "fs/VFS.h"
#include "fs/devices/ConsoleDevice.h"
#include "fs/devices/FramebufferDevice.h"
#include "fs/devices/NullDevice.h"
#include "fs/devices/ZeroDevice.h"
#include "fs/tmpfs/FileSystem.h"
#include "thread/Thread.h"
#include <luna/Vector.h>

struct DeviceDescriptor
{
    SharedPtr<Device> device;
    u32 major;
    u32 minor;
    const char* name;
    mode_t mode;
};

Vector<DeviceDescriptor> g_available_devices = {};

SharedPtr<VFS::FileSystem> g_device_fs;

namespace DeviceRegistry
{
    Result<SharedPtr<Device>> fetch_special_device(u32 major, u32 minor)
    {
        for (const auto& descriptor : g_available_devices)
        {
            if (descriptor.major == major && descriptor.minor == minor) return descriptor.device;
        }

        return err(ENODEV);
    }

    Result<void> register_special_device(u32 major, u32 minor, SharedPtr<Device> device, const char* name, mode_t mode)
    {
        for (const auto& descriptor : g_available_devices)
        {
            if (descriptor.major == major && descriptor.minor == minor) return err(EEXIST);
        }

        kdbgln("DeviceRegistry: registered new device type %u:%u at path /dev/%s", major, minor, name);

        auto desc = DeviceDescriptor { .device = device, .major = major, .minor = minor, .name = name, .mode = mode };

        TRY(g_available_devices.try_append(desc));

        TRY(create_special_device_inode(desc));

        return {};
    }

    Result<void> create_special_device_inode(DeviceDescriptor& descriptor)
    {
        auto inode = TRY(g_device_fs->create_device_inode(descriptor.major, descriptor.minor));
        inode->chmod(descriptor.mode);
        TRY(g_device_fs->root_inode()->add_entry(inode, descriptor.name));

        return {};
    }

    Result<void> init()
    {
        auto device_fs = TRY(TmpFS::FileSystem::create());
        TRY(VFS::mount("/dev", device_fs, Credentials {}));
        g_device_fs = device_fs;

        NullDevice::create();
        ZeroDevice::create();
        ConsoleDevice::create();
        FramebufferDevice::create();

        return {};
    }
}