Implement read data in ext2 inode

2 files changed, 35 insertions, 3 deletions

diff --git a/kernel/src/filesystem/ext2/inode.cpp b/kernel/src/filesystem/ext2/inode.cpp
index 4d36e66..7f4cf69 100644
--- a/kernel/src/filesystem/ext2/inode.cpp
+++ b/kernel/src/filesystem/ext2/inode.cpp
@@ -2,9 +2,13 @@
 
 #include "kapi/system.hpp"
 
+#include "kernel/devices/block_device_utils.hpp"
+#include "kernel/filesystem/ext2/filesystem.hpp"
 #include "kernel/filesystem/inode.hpp"
 
+#include <algorithm>
 #include <cstddef>
+#include <cstdint>
 
 namespace kernel::filesystem::ext2
 {
@@ -18,10 +22,33 @@ namespace kernel::filesystem::ext2
     }
   }
 
-  auto inode::read(void * /*buffer*/, size_t /*offset*/, size_t /*size*/) const -> size_t
+  auto inode::read(void * buffer, size_t offset, size_t size) const -> size_t
   {
-    // TODO BA-FS26 implement
-    return 0;
+    auto block_index = offset / m_filesystem->get_block_size();
+    auto in_block_offset = offset % m_filesystem->get_block_size();
+
+    auto bytes_read = 0uz;
+
+    while (bytes_read < size)
+    {
+      auto const block_number = m_filesystem->map_inode_block_index_to_global_block_number(block_index, m_data);
+      if (block_number == 0)  // TODO BA-FS26 really correct?
+      {
+        break;
+      }
+
+      auto const block_start_offset = block_number * m_filesystem->get_block_size();
+      auto const read_offset = block_start_offset + in_block_offset;
+      auto const bytes_to_read = std::min(size - bytes_read, m_filesystem->get_block_size() - in_block_offset);
+
+      bytes_read += kernel::devices::block_device_utils::read(
+          m_filesystem->device(), static_cast<uint8_t *>(buffer) + bytes_read, read_offset, bytes_to_read);
+
+      block_index++;
+      in_block_offset = 0;  // After the first block, we always start at the beginning of the block
+    }
+
+    return bytes_read;
   }
 
   auto inode::write(void const * /*buffer*/, size_t /*offset*/, size_t /*size*/) -> size_t
diff --git a/kernel/src/filesystem/filesystem.cpp b/kernel/src/filesystem/filesystem.cpp
index a06eb80..26c57b6 100644
--- a/kernel/src/filesystem/filesystem.cpp
+++ b/kernel/src/filesystem/filesystem.cpp
@@ -49,4 +49,9 @@ namespace kernel::filesystem
   {
     return m_root_inode;
   }
+
+  auto filesystem::device() const -> kstd::shared_ptr<kapi::devices::device> const &
+  {
+    return m_device;
+  }
 }  // namespace kernel::filesystem
\ No newline at end of file