kernel/ext2: Add support for symbolic links

kernel/src/fs/ext2/Inode.cpp

@@ -1,5 +1,5 @@
 #include "fs/ext2/Inode.h"
-#include <luna/String.h>
+#include <luna/Buffer.h>
 
 namespace Ext2
 {
@@ -162,4 +162,29 @@ namespace Ext2
 
         return m_entries[index];
     }
+
+    Result<StringView> Inode::readlink()
+    {
+        check(m_type == VFS::InodeType::Symlink);
+
+        if (!m_link.is_empty()) return m_link.view();
+
+        const usize length = size();
+
+        if (length < 60)
+        {
+            // The symlink location is stored inline within the inode's data blocks.
+            m_link = TRY(String::from_string_view(
+                StringView::from_fixed_size_cstring((char*)&m_raw_inode.direct_pointers[0], length)));
+
+            return m_link.view();
+        }
+
+        Buffer buf = TRY(Buffer::create_sized(length));
+        TRY(read(buf.data(), 0, length));
+
+        m_link = TRY(String::from_string_view(StringView::from_fixed_size_cstring((char*)buf.data(), length)));
+
+        return m_link.view();
+    }
 }

kernel/src/fs/ext2/Inode.h

@@ -1,5 +1,6 @@
 #pragma once
 #include "fs/ext2/FileSystem.h"
+#include <luna/String.h>
 
 #define EXT2_FIFO 0x1000
 #define EXT2_CHR 0x2000
@@ -125,6 +126,8 @@ namespace Ext2
             return false;
         }
 
+        Result<StringView> readlink() override;
+
         Result<void> lazy_initialize_dir() const;
 
         // FIXME: Implement readlink() and device numbers.
@@ -138,6 +141,8 @@ namespace Ext2
         FileSystem* m_fs;
         ino_t m_inum;
 
+        String m_link;
+
         mutable Vector<VFS::DirectoryEntry> m_entries;
         mutable bool m_dir_already_lazily_initialized { false };