implement sparse files, fix bug with reading more than inode size

1 files changed, 14 insertions, 8 deletions

diff --git a/kernel/src/filesystem/ext2/inode.cpp b/kernel/src/filesystem/ext2/inode.cpp
index 303838e..cfe0a35 100644
--- a/kernel/src/filesystem/ext2/inode.cpp
+++ b/kernel/src/filesystem/ext2/inode.cpp
@@ -40,23 +40,29 @@ namespace kernel::filesystem::ext2
 
     auto bytes_read = 0uz;
 
-    while (bytes_read < size)
+    while (bytes_read < requested_size)
     {
       auto const block_number = m_filesystem->map_inode_block_index_to_global_block_number(block_index, m_data);
-      // TODO BA-FS26 really correct? sparse files -> 0 means a full block with zeros --> function
-      // map_inode_block_index_to_global_block_number should return 0 if not possible to find an block
-      if (block_number == 0)
+      if (block_number == -1)
       {
         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(requested_size - bytes_read, m_filesystem->get_block_size() - in_block_offset);
+      if (block_number == 0)
+      {
+        kstd::libc::memset(static_cast<uint8_t *>(buffer) + bytes_read, 0, bytes_to_read);
+        bytes_read += bytes_to_read;
+      }
+      else
+      {
+        auto const block_start_offset = block_number * m_filesystem->get_block_size();
+        auto const read_offset = block_start_offset + in_block_offset;
 
-      bytes_read +=
-          m_filesystem->backing_inode()->read(static_cast<uint8_t *>(buffer) + bytes_read, read_offset, bytes_to_read);
+        bytes_read += m_filesystem->backing_inode()->read(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