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Kernel: Expose device presence in /sys/dev/char and /sys/dev/block

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These files are not marked as block devices or character devices so they
are not meant to be used as device nodes. The filenames are formatted to
the pattern "major:minor", but a Userland program need to call the parse
these format and inspect the the major and minor numbers and create the
real device nodes in /dev.

Later on, it might be a good idea to ensure we don't create new
SysFSComponents on the heap for each Device, but rather generate
them only when required (and preferably to not create a SysFSComponent
at all if possible).
This commit is contained in:
Liav A 2021-08-14 11:40:37 +03:00 • committed by Andreas Kling
parent 009feefee0
commit 6a9c717a30
5 changed files with 183 additions and 2 deletions
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8
Kernel/FileSystem/SysFS.cpp
View file

@ -6,6 +6,7 @@
#include <AK/Singleton.h>
#include <AK/StringView.h>
#include <Kernel/Devices/Device.h>
#include <Kernel/FileSystem/SysFS.h>
#include <Kernel/Sections.h>
@ -35,6 +36,11 @@ UNMAP_AFTER_INIT void SysFSComponentRegistry::register_new_component(SysFSCompon
m_root_directory->m_components.append(component);
}
SysFSComponentRegistry::DevicesList& SysFSComponentRegistry::devices_list()
{
return m_devices_list;
}
NonnullRefPtr<SysFSRootDirectory> SysFSRootDirectory::create()
{
return adopt_ref(*new (nothrow) SysFSRootDirectory);
@ -57,7 +63,9 @@ SysFSRootDirectory::SysFSRootDirectory()
: SysFSDirectory(".")
{
auto buses_directory = SysFSBusDirectory::must_create(*this);
auto devices_directory = SysFSDevicesDirectory::must_create(*this);
m_components.append(buses_directory);
m_components.append(devices_directory);
m_buses_directory = buses_directory;
}

51
Kernel/FileSystem/SysFS.h
View file

@ -9,9 +9,11 @@
#include <Kernel/FileSystem/FileSystem.h>
#include <Kernel/FileSystem/Inode.h>
#include <Kernel/FileSystem/SysFSComponent.h>
#include <Kernel/Locking/MutexProtected.h>
namespace Kernel {
class SysFSDevicesDirectory;
class SysFSRootDirectory final : public SysFSDirectory {
friend class SysFSComponentRegistry;
@ -24,6 +26,50 @@ private:
RefPtr<SysFSBusDirectory> m_buses_directory;
};
class SysFSDeviceComponent final
: public SysFSComponent
, public Weakable<SysFSDeviceComponent> {
friend class SysFSComponentRegistry;
public:
static NonnullRefPtr<SysFSDeviceComponent> must_create(Device const&);
Device const& device() const { return *m_associated_device; }
private:
explicit SysFSDeviceComponent(Device const&);
IntrusiveListNode<SysFSDeviceComponent, NonnullRefPtr<SysFSDeviceComponent>> m_list_node;
RefPtr<Device> m_associated_device;
};
class SysFSDevicesDirectory final : public SysFSDirectory {
public:
static NonnullRefPtr<SysFSDevicesDirectory> must_create(SysFSRootDirectory const&);
private:
explicit SysFSDevicesDirectory(SysFSRootDirectory const&);
};
class SysFSBlockDevicesDirectory final : public SysFSDirectory {
public:
static NonnullRefPtr<SysFSBlockDevicesDirectory> must_create(SysFSDevicesDirectory const&);
virtual KResult traverse_as_directory(unsigned, Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
virtual RefPtr<SysFSComponent> lookup(StringView name) override;
private:
explicit SysFSBlockDevicesDirectory(SysFSDevicesDirectory const&);
};
class SysFSCharacterDevicesDirectory final : public SysFSDirectory {
public:
static NonnullRefPtr<SysFSCharacterDevicesDirectory> must_create(SysFSDevicesDirectory const&);
virtual KResult traverse_as_directory(unsigned, Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
virtual RefPtr<SysFSComponent> lookup(StringView name) override;
private:
explicit SysFSCharacterDevicesDirectory(SysFSDevicesDirectory const&);
};
class SysFSBusDirectory : public SysFSDirectory {
friend class SysFSComponentRegistry;
@ -35,6 +81,8 @@ private:
};
class SysFSComponentRegistry {
using DevicesList = MutexProtected<IntrusiveList<SysFSDeviceComponent, NonnullRefPtr<SysFSDeviceComponent>, &SysFSDeviceComponent::m_list_node>>;
public:
static SysFSComponentRegistry& the();
@ -49,9 +97,12 @@ public:
void register_new_bus_directory(SysFSDirectory&);
SysFSBusDirectory& buses_directory();
DevicesList& devices_list();
private:
Mutex m_lock;
NonnullRefPtr<SysFSRootDirectory> m_root_directory;
DevicesList m_devices_list;
};
class SysFS final : public FileSystem {