kernel: Implement creating file inodes in tmpfs directories

kernel/src/fs/VFS.h

@@ -14,8 +14,12 @@ namespace VFS
     class Inode
     {
       public:
-        virtual Result<Inode*> find(const char* name) const = 0;
+        // Directory-specific methods
+        virtual Result<SharedPtr<Inode>> find(const char* name) const = 0;
 
+        virtual Result<SharedPtr<Inode>> create_file(const char* name) = 0;
+
+        // Generic methods
         virtual FileSystem& fs() const = 0;
 
         virtual ~Inode() = default;
@@ -28,7 +32,12 @@ namespace VFS
     class FileInode : Inode
     {
       public:
-        Result<Inode*> find(const char*) const override
+        Result<SharedPtr<Inode>> find(const char*) const override
+        {
+            return err(ENOTDIR);
+        }
+
+        Result<SharedPtr<Inode>> create_file(const char*) override
         {
             return err(ENOTDIR);
         }
@@ -48,6 +57,8 @@ namespace VFS
 
         virtual Result<SharedPtr<Inode>> create_file_inode() = 0;
 
+        virtual Result<SharedPtr<Inode>> create_dir_inode() = 0;
+
         virtual ~FileSystem() = default;
     };
 

kernel/src/fs/tmpfs/FileSystem.cpp

@@ -1,12 +1,13 @@
 #include "fs/tmpfs/FileSystem.h"
 #include <luna/Alloc.h>
+#include <luna/Ignore.h>
 
 namespace TmpFS
 {
     Result<SharedPtr<VFS::FileSystem>> FileSystem::create()
     {
         SharedPtr<FileSystem> fs = TRY(adopt_shared(new (std::nothrow) FileSystem()));
-        SharedPtr<VFS::Inode> root = TRY(fs->create_file_inode());
+        SharedPtr<VFS::Inode> root = TRY(fs->create_dir_inode());
         fs->set_root(root);
         return (SharedPtr<VFS::FileSystem>)fs;
     }
@@ -21,8 +22,48 @@ namespace TmpFS
         return (SharedPtr<VFS::Inode>)inode;
     }
 
+    Result<SharedPtr<VFS::Inode>> FileSystem::create_dir_inode()
+    {
+        SharedPtr<DirInode> inode = TRY(make_shared<DirInode>());
+        TRY(inode->add_entry(inode, "."));
+
+        inode->set_fs(*this, {});
+        inode->set_inode_number(m_next_inode_number, {});
+        TRY(m_inodes.try_append(inode));
+        m_next_inode_number++;
+        return (SharedPtr<VFS::Inode>)inode;
+    }
+
     void FileSystem::set_root(SharedPtr<VFS::Inode> root)
     {
         m_root_inode = root;
     }
+
+    Result<SharedPtr<VFS::Inode>> DirInode::find(const char* name) const
+    {
+        for (const auto& entry : m_entries)
+        {
+            if (!strcmp(name, entry.name.chars())) return entry.inode;
+        }
+
+        return err(ENOENT);
+    }
+
+    Result<void> DirInode::add_entry(SharedPtr<VFS::Inode> inode, const char* name)
+    {
+        Entry entry = { inode, TRY(OwnedStringView::from_string_literal(name)) };
+
+        TRY(m_entries.try_append(move(entry)));
+
+        return {};
+    }
+
+    Result<SharedPtr<VFS::Inode>> DirInode::create_file(const char* name)
+    {
+        auto inode = TRY(m_fs->create_file_inode());
+
+        TRY(add_entry(inode, name));
+
+        return inode;
+    }
 }

kernel/src/fs/tmpfs/FileSystem.h

@@ -2,6 +2,7 @@
 #include "fs/VFS.h"
 #include <luna/Atomic.h>
 #include <luna/Badge.h>
+#include <luna/OwnedStringView.h>
 #include <luna/Vector.h>
 
 namespace TmpFS
@@ -15,6 +16,7 @@ namespace TmpFS
         }
 
         Result<SharedPtr<VFS::Inode>> create_file_inode() override;
+        Result<SharedPtr<VFS::Inode>> create_dir_inode() override;
 
         static Result<SharedPtr<VFS::FileSystem>> create();
 
@@ -62,4 +64,55 @@ namespace TmpFS
         VFS::FileSystem* m_fs;
         usize m_inode_number;
     };
+
+    class DirInode : public VFS::Inode
+    {
+      public:
+        DirInode() = default;
+
+        void set_fs(FileSystem& fs, Badge<FileSystem>)
+        {
+            m_fs = &fs;
+        }
+
+        void set_inode_number(usize inum, Badge<FileSystem>)
+        {
+            m_inode_number = inum;
+        }
+
+        Result<SharedPtr<VFS::Inode>> find(const char* name) const override;
+
+        VFS::FileSystem& fs() const override
+        {
+            return *m_fs;
+        }
+
+        usize inode_number() const override
+        {
+            return m_inode_number;
+        }
+
+        VFS::InodeType type() const override
+        {
+            return VFS::InodeType::Directory;
+        }
+
+        Result<SharedPtr<VFS::Inode>> create_file(const char* name) override;
+
+        Result<void> add_entry(SharedPtr<VFS::Inode> inode, const char* name);
+
+        virtual ~DirInode() = default;
+
+      private:
+        VFS::FileSystem* m_fs;
+        usize m_inode_number;
+
+        struct Entry
+        {
+            SharedPtr<VFS::Inode> inode;
+            OwnedStringView name;
+        };
+
+        Vector<Entry> m_entries;
+    };
 }

kernel/src/main.cpp

@@ -61,6 +61,9 @@ Result<void> init()
     VFS::Inode& root_inode = VFS::root_inode();
     kinfoln("root inode number: %zu", root_inode.inode_number());
 
+    TRY(root_inode.create_file("usr"));
+    kinfoln("root inode's 'usr' entry inode number: %zu", TRY(root_inode.find("usr"))->inode_number());
+
     TarStream::Entry entry;
     while (TRY(g_initrd.read_next_entry(entry)))
     {