Kernel: Rewrite ProcFS.

Now the filesystem is generated on-the-fly instead of manually adding and removing inodes as processes spawn and die. The code is convoluted and bloated as I wrote it while sleepless. However, it's still vastly better than the old ProcFS, so I'm committing it. I also added /proc/PID/fd/N symlinks for each of a process's open fd's.
2025-07-25 06:47:35 +00:00 · 2019-02-03 12:33:11 +01:00 · 2019-02-03 12:33:11 +01:00 · 5e9ba2ac84
commit 5e9ba2ac84
parent ab56f36bfb
13 changed files with 1133 additions and 468 deletions
--- a/Kernel/ProcFS.h
+++ b/Kernel/ProcFS.h
@ -0,0 +1,96 @@
+#pragma once
+
+#include <AK/Lock.h>
+#include <AK/Types.h>
+#include <Kernel/FileSystem.h>
+
+class Process;
+
+class ProcFSInode;
+
+class ProcFS final : public FS {
+    friend class ProcFSInode;
+public:
+    static ProcFS& the() PURE;
+
+    virtual ~ProcFS() override;
+    static RetainPtr<ProcFS> create();
+
+    virtual bool initialize() override;
+    virtual const char* class_name() const override;
+
+    virtual InodeIdentifier root_inode() const override;
+    virtual RetainPtr<Inode> get_inode(InodeIdentifier) const override;
+
+    virtual RetainPtr<Inode> create_inode(InodeIdentifier parent_id, const String& name, mode_t, unsigned size, int& error) override;
+    virtual RetainPtr<Inode> create_directory(InodeIdentifier parent_id, const String& name, mode_t, int& error) override;
+
+    void add_sys_file(String&&, Function<ByteBuffer(ProcFSInode&)>&& read_callback, Function<ssize_t(ProcFSInode&, const ByteBuffer&)>&& write_callback);
+    void add_sys_bool(String&&, bool*, Function<void()>&& notify_callback = nullptr);
+
+private:
+    ProcFS();
+
+    struct ProcFSDirectoryEntry {
+        ProcFSDirectoryEntry() { }
+        ProcFSDirectoryEntry(const char* a_name, unsigned a_proc_file_type, Function<ByteBuffer(InodeIdentifier)>&& a_read_callback = nullptr, Function<ssize_t(InodeIdentifier, const ByteBuffer&)>&& a_write_callback = nullptr, RetainPtr<ProcFSInode>&& a_inode = nullptr)
+            : name(a_name)
+            , proc_file_type(a_proc_file_type)
+            , read_callback(move(a_read_callback))
+            , write_callback(move(a_write_callback))
+            , inode(move(a_inode))
+        {
+        }
+
+        const char* name { nullptr };
+        unsigned proc_file_type { 0 };
+        Function<ByteBuffer(InodeIdentifier)> read_callback;
+        Function<ssize_t(InodeIdentifier, const ByteBuffer&)> write_callback;
+        RetainPtr<ProcFSInode> inode;
+        InodeIdentifier identifier(unsigned fsid) const;
+    };
+
+    ProcFSDirectoryEntry* get_directory_entry(InodeIdentifier) const;
+
+    Vector<ProcFSDirectoryEntry> m_entries;
+    Vector<ProcFSDirectoryEntry> m_sys_entries;
+
+    mutable Lock m_inodes_lock;
+    mutable HashMap<unsigned, ProcFSInode*> m_inodes;
+    RetainPtr<ProcFSInode> m_root_inode;
+};
+
+struct ProcFSInodeCustomData {
+    virtual ~ProcFSInodeCustomData();
+};
+
+class ProcFSInode final : public Inode {
+    friend class ProcFS;
+public:
+    virtual ~ProcFSInode() override;
+
+    void set_custom_data(OwnPtr<ProcFSInodeCustomData>&& custom_data) { m_custom_data = move(custom_data); }
+    ProcFSInodeCustomData* custom_data() { return m_custom_data.ptr(); }
+    const ProcFSInodeCustomData* custom_data() const { return m_custom_data.ptr(); }
+
+private:
+    // ^Inode
+    virtual ssize_t read_bytes(off_t, size_t, byte* buffer, FileDescriptor*) const override;
+    virtual InodeMetadata metadata() const override;
+    virtual bool traverse_as_directory(Function<bool(const FS::DirectoryEntry&)>) const override;
+    virtual InodeIdentifier lookup(const String& name) override;
+    virtual String reverse_lookup(InodeIdentifier) override;
+    virtual void flush_metadata() override;
+    virtual ssize_t write_bytes(off_t, size_t, const byte* buffer, FileDescriptor*) override;
+    virtual bool add_child(InodeIdentifier child_id, const String& name, byte file_type, int& error) override;
+    virtual bool remove_child(const String& name, int& error) override;
+    virtual RetainPtr<Inode> parent() const override;
+    virtual size_t directory_entry_count() const override;
+    virtual bool chmod(mode_t, int& error) override;
+
+    ProcFS& fs() { return static_cast<ProcFS&>(Inode::fs()); }
+    const ProcFS& fs() const { return static_cast<const ProcFS&>(Inode::fs()); }
+    ProcFSInode(ProcFS&, unsigned index);
+
+    OwnPtr<ProcFSInodeCustomData> m_custom_data;
+};