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Kernel/SysFS: Add Symbolic link functionality to the filesystem
This will be used later on to help connecting a node at /sys/dev/block/ that represents a Storage device to a directory in /sys/devices/storage/ with details on that device in that directory.
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7e88bbe550
commit
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4 changed files with 104 additions and 0 deletions
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@ -131,6 +131,31 @@ ErrorOr<void> SysFSInode::truncate(u64 size)
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return m_associated_component->truncate(size);
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}
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ErrorOr<NonnullRefPtr<SysFSLinkInode>> SysFSLinkInode::try_create(SysFS const& sysfs, SysFSComponent const& component)
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{
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return adopt_nonnull_ref_or_enomem(new (nothrow) SysFSLinkInode(sysfs, component));
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}
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SysFSLinkInode::SysFSLinkInode(SysFS const& fs, SysFSComponent const& component)
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: SysFSInode(fs, component)
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{
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}
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SysFSLinkInode::~SysFSLinkInode() = default;
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InodeMetadata SysFSLinkInode::metadata() const
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{
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// NOTE: No locking required as m_associated_component or its component index will never change during our lifetime.
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InodeMetadata metadata;
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metadata.inode = { fsid(), m_associated_component->component_index() };
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metadata.mode = S_IFLNK | S_IRUSR | S_IRGRP | S_IROTH | S_IXOTH;
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metadata.uid = 0;
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metadata.gid = 0;
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metadata.size = 0;
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metadata.mtime = TimeManagement::boot_time();
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return metadata;
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}
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ErrorOr<NonnullRefPtr<SysFSDirectoryInode>> SysFSDirectoryInode::try_create(SysFS const& sysfs, SysFSComponent const& component)
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{
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return adopt_nonnull_ref_or_enomem(new (nothrow) SysFSDirectoryInode(sysfs, component));
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@ -62,6 +62,19 @@ protected:
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NonnullRefPtr<SysFSComponent> m_associated_component;
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};
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class SysFSLinkInode : public SysFSInode {
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friend class SysFS;
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public:
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static ErrorOr<NonnullRefPtr<SysFSLinkInode>> try_create(SysFS const&, SysFSComponent const&);
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virtual ~SysFSLinkInode() override;
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protected:
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SysFSLinkInode(SysFS const&, SysFSComponent const&);
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// ^Inode
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virtual InodeMetadata metadata() const override;
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};
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class SysFSDirectoryInode : public SysFSInode {
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friend class SysFS;
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@ -57,6 +57,53 @@ mode_t SysFSComponent::permissions() const
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return S_IRUSR | S_IRGRP | S_IROTH;
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}
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ErrorOr<size_t> SysFSSymbolicLink::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, OpenFileDescription*) const
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{
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auto blob = TRY(try_to_generate_buffer());
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if ((size_t)offset >= blob->size())
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return 0;
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ssize_t nread = min(static_cast<off_t>(blob->size() - offset), static_cast<off_t>(count));
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TRY(buffer.write(blob->data() + offset, nread));
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return nread;
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}
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ErrorOr<NonnullOwnPtr<KBuffer>> SysFSSymbolicLink::try_to_generate_buffer() const
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{
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auto return_path_to_mount_point = TRY(try_generate_return_path_to_mount_point());
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if (!m_pointed_component)
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return Error::from_errno(EIO);
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auto pointed_component_base_name = MUST(KString::try_create(m_pointed_component->name()));
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auto pointed_component_relative_path = MUST(m_pointed_component->relative_path(move(pointed_component_base_name), 0));
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auto full_return_and_target_path = TRY(KString::formatted("{}{}", return_path_to_mount_point->view(), pointed_component_relative_path->view()));
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return KBuffer::try_create_with_bytes("SysFSSymbolicLink"sv, full_return_and_target_path->view().bytes());
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}
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static ErrorOr<NonnullOwnPtr<KString>> generate_return_path_to_mount_point(NonnullOwnPtr<KString> current_path, size_t remaining_hop)
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{
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if (remaining_hop == 0)
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return current_path;
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auto new_path = TRY(KString::formatted("../{}"sv, current_path->view()));
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remaining_hop--;
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return generate_return_path_to_mount_point(move(new_path), remaining_hop);
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}
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ErrorOr<NonnullOwnPtr<KString>> SysFSSymbolicLink::try_generate_return_path_to_mount_point() const
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{
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auto hops_from_mountpoint = TRY(relative_path_hops_count_from_mountpoint());
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if (hops_from_mountpoint == 0)
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return KString::try_create("./"sv);
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auto start_return_path = TRY(KString::try_create("./"sv));
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return generate_return_path_to_mount_point(move(start_return_path), hops_from_mountpoint);
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}
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SysFSSymbolicLink::SysFSSymbolicLink(SysFSDirectory const& parent_directory, SysFSComponent const& pointed_component)
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: SysFSComponent(parent_directory)
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, m_pointed_component(pointed_component)
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{
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}
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ErrorOr<void> SysFSDirectory::traverse_as_directory(FileSystemID fsid, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)> callback) const
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{
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MutexLocker locker(SysFSComponentRegistry::the().get_lock());
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@ -91,6 +138,11 @@ ErrorOr<NonnullRefPtr<SysFSInode>> SysFSDirectory::to_inode(SysFS const& sysfs_i
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return TRY(SysFSDirectoryInode::try_create(sysfs_instance, *this));
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}
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ErrorOr<NonnullRefPtr<SysFSInode>> SysFSSymbolicLink::to_inode(SysFS const& sysfs_instance) const
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{
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return TRY(SysFSLinkInode::try_create(sysfs_instance, *this));
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}
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ErrorOr<NonnullRefPtr<SysFSInode>> SysFSComponent::to_inode(SysFS const& sysfs_instance) const
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{
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return SysFSInode::try_create(sysfs_instance, *this);
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@ -56,6 +56,20 @@ private:
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InodeIndex m_component_index {};
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};
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class SysFSSymbolicLink : public SysFSComponent {
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public:
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virtual ErrorOr<size_t> read_bytes(off_t, size_t, UserOrKernelBuffer&, OpenFileDescription*) const override final;
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virtual ErrorOr<NonnullRefPtr<SysFSInode>> to_inode(SysFS const& sysfs_instance) const override final;
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protected:
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ErrorOr<NonnullOwnPtr<KString>> try_generate_return_path_to_mount_point() const;
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ErrorOr<NonnullOwnPtr<KBuffer>> try_to_generate_buffer() const;
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explicit SysFSSymbolicLink(SysFSDirectory const& parent_directory, SysFSComponent const& pointed_component);
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RefPtr<SysFSComponent> m_pointed_component;
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};
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class SysFSDirectory : public SysFSComponent {
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public:
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virtual ErrorOr<void> traverse_as_directory(FileSystemID, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>) const override;
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