VFS: Add virtual method get() for getdents() and make existence checking occur in add_entry()

kernel/src/fs/VFS.h

@@ -1,5 +1,6 @@
 #pragma once
 #include <luna/SharedPtr.h>
+#include <luna/StaticString.h>
 #include <sys/types.h>
 
 namespace VFS
@@ -12,6 +13,14 @@ namespace VFS
     };
 
     class FileSystem;
+    class Inode;
+
+    struct DirectoryEntry
+    {
+      public:
+        SharedPtr<Inode> inode;
+        StaticString<128> name;
+    };
 
     class Inode
     {
@@ -19,6 +28,8 @@ namespace VFS
         // Directory-specific methods
         virtual Result<SharedPtr<Inode>> find(const char* name) const = 0;
 
+        virtual Option<DirectoryEntry> get(usize index) const = 0;
+
         virtual Result<SharedPtr<Inode>> create_file(const char* name) = 0;
 
         virtual Result<SharedPtr<Inode>> create_subdirectory(const char* name) = 0;
@@ -60,6 +71,11 @@ namespace VFS
             return err(ENOTDIR);
         }
 
+        Option<DirectoryEntry> get(usize) const override
+        {
+            return {};
+        }
+
         Result<SharedPtr<Inode>> create_file(const char*) override
         {
             return err(ENOTDIR);
@@ -96,6 +112,11 @@ namespace VFS
             return err(ENOTDIR);
         }
 
+        Option<DirectoryEntry> get(usize) const override
+        {
+            return {};
+        }
+
         Result<SharedPtr<Inode>> create_file(const char*) override
         {
             return err(ENOTDIR);

kernel/src/fs/tmpfs/FileSystem.cpp

@@ -63,9 +63,18 @@ namespace TmpFS
         return err(ENOENT);
     }
 
+    Option<VFS::DirectoryEntry> DirInode::get(usize index) const
+    {
+        if (index >= m_entries.size()) return {};
+
+        return m_entries[index];
+    }
+
     Result<void> DirInode::add_entry(SharedPtr<VFS::Inode> inode, const char* name)
     {
-        Entry entry { inode, name };
+        if (find(name).has_value()) return err(EEXIST);
+
+        VFS::DirectoryEntry entry { inode, name };
 
         TRY(m_entries.try_append(move(entry)));
 
@@ -74,8 +83,6 @@ namespace TmpFS
 
     Result<SharedPtr<VFS::Inode>> DirInode::create_file(const char* name)
     {
-        if (find(name).has_value()) return err(EEXIST);
-
         auto inode = TRY(m_fs->create_file_inode());
 
         TRY(add_entry(inode, name));
@@ -85,8 +92,6 @@ namespace TmpFS
 
     Result<SharedPtr<VFS::Inode>> DirInode::create_subdirectory(const char* name)
     {
-        if (find(name).has_value()) return err(EEXIST);
-
         auto inode = TRY(m_fs->create_dir_inode(m_self));
 
         TRY(add_entry(inode, name));

kernel/src/fs/tmpfs/FileSystem.h

@@ -185,6 +185,7 @@ namespace TmpFS
         }
 
         Result<SharedPtr<VFS::Inode>> find(const char* name) const override;
+        Option<VFS::DirectoryEntry> get(usize index) const override;
 
         Result<usize> read(u8*, usize, usize) const override
         {
@@ -251,12 +252,6 @@ namespace TmpFS
 
         SharedPtr<VFS::Inode> m_self;
 
-        struct Entry
-        {
-            SharedPtr<VFS::Inode> inode;
-            StaticString<128> name;
-        };
-
-        Vector<Entry> m_entries;
+        Vector<VFS::DirectoryEntry> m_entries;
     };
 }

kernel/src/sys/mknod.cpp

@@ -24,8 +24,6 @@ Result<u64> sys_mknod(Registers*, SyscallArgs args)
 
     auto parent = TRY(VFS::resolve_path(dirname.chars()));
 
-    if (parent->find(basename.chars()).has_value()) return err(EEXIST);
-
     auto inode = TRY(parent->fs().create_device_inode(maj, min));
     TRY(parent->add_entry(inode, basename.chars()));