Merge branch 'symbolic-links' into 'develop-BA-FS26'

Symbolic links

See merge request teachos/kernel!29

1 files changed, 38 insertions, 4 deletions

diff --git a/kernel/src/filesystem/ext2/inode.cpp b/kernel/src/filesystem/ext2/inode.cpp
index c45c41e..1914c70 100644
--- a/kernel/src/filesystem/ext2/inode.cpp
+++ b/kernel/src/filesystem/ext2/inode.cpp
@@ -5,15 +5,17 @@
 
 #include <kapi/system.hpp>
 
+#include <kstd/cstring>
+
 #include <algorithm>
 #include <cstddef>
 #include <cstdint>
 
 namespace kernel::filesystem::ext2
 {
-  inode::inode(filesystem * fs)
-      : kernel::filesystem::inode(inode_kind::regular)
-      , m_filesystem(fs)
+  inode::inode(filesystem * fs, inode_data const & data)
+      : m_filesystem(fs)
+      , m_data(data)
   {
     if (!m_filesystem)
     {
@@ -23,6 +25,17 @@ namespace kernel::filesystem::ext2
 
   auto inode::read(void * buffer, size_t offset, size_t size) const -> size_t
   {
+    // TODO BA-FS26 use revision 1 size
+    auto const max_readable = static_cast<size_t>(m_data.size) - offset;
+    auto const requested_size = std::min(size, max_readable);
+
+    if (is_symbolic_link() && m_data.size <= sizeof(m_data.block))
+    {
+      auto inline_target = reinterpret_cast<uint8_t const *>(m_data.block.data());
+      kstd::libc::memcpy(static_cast<uint8_t *>(buffer), inline_target + offset, requested_size);
+      return requested_size;
+    }
+
     auto block_index = offset / m_filesystem->get_block_size();
     auto in_block_offset = offset % m_filesystem->get_block_size();
 
@@ -40,7 +53,8 @@ namespace kernel::filesystem::ext2
 
       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);
+      auto const bytes_to_read =
+          std::min(requested_size - bytes_read, m_filesystem->get_block_size() - in_block_offset);
 
       bytes_read +=
           m_filesystem->backing_inode()->read(static_cast<uint8_t *>(buffer) + bytes_read, read_offset, bytes_to_read);
@@ -57,4 +71,24 @@ namespace kernel::filesystem::ext2
     kapi::system::panic("[EXT2] inode::write is not implemented yet");
     return 0;
   }
+
+  [[nodiscard]] auto inode::data() const -> inode_data const &
+  {
+    return m_data;
+  }
+
+  auto inode::is_regular() const -> bool
+  {
+    return (m_data.mode & constants::mode_mask) == constants::mode_regular;
+  }
+
+  auto inode::is_directory() const -> bool
+  {
+    return (m_data.mode & constants::mode_mask) == constants::mode_directory;
+  }
+
+  auto inode::is_symbolic_link() const -> bool
+  {
+    return (m_data.mode & constants::mode_mask) == constants::mode_symbolic_link;
+  }
 }  // namespace kernel::filesystem::ext2