Merge branch 'vfs' into 'develop-BA-FS26'

implement basic vfs

See merge request teachos/kernel!16

1 files changed, 126 insertions, 0 deletions

diff --git a/kernel/src/filesystem/device_inode.cpp b/kernel/src/filesystem/device_inode.cpp
new file mode 100644
index 0000000..64cd6e9
--- /dev/null
+++ b/kernel/src/filesystem/device_inode.cpp
@@ -0,0 +1,126 @@
+#include "kernel/filesystem/device_inode.hpp"
+
+#include "kapi/system.hpp"
+
+#include "kernel/devices/block_device.hpp"
+#include "kernel/devices/device.hpp"
+#include "kernel/filesystem/inode.hpp"
+
+#include <kstd/cstring>
+#include <kstd/memory>
+#include <kstd/vector>
+
+#include <algorithm>
+#include <cstddef>
+
+namespace filesystem
+{
+  device_inode::device_inode(kstd::shared_ptr<devices::device> const & device)
+      : inode(inode_kind::device)
+      , m_device(device)
+  {
+    if (!device)
+    {
+      kapi::system::panic("[FILESYSTEM] device_inode constructed with null device.");
+    }
+  }
+
+  auto device_inode::read(void * buffer, size_t offset, size_t size) const -> size_t
+  {
+    if (m_device->is_block_device())
+    {
+      return process_blocks(offset, size, buffer,
+                            [](size_t idx, size_t off, size_t len, size_t done, devices::block_device * device,
+                               std::byte * scratch, void * buffer) {
+                              auto * out = static_cast<std::byte *>(buffer);
+                              if (off == 0 && len == device->block_size())
+                              {
+                                device->read_block(idx, out + done);
+                              }
+                              else
+                              {
+                                device->read_block(idx, scratch);
+                                kstd::libc::memcpy(out + done, scratch + off, len);
+                              }
+                            });
+    }
+    else
+    {
+      kapi::system::panic("[FILESYSTEM] device_file::read called on non-block device.");
+    }
+  }
+
+  auto device_inode::write(void const * buffer, size_t offset, size_t size) -> size_t
+  {
+    if (m_device->is_block_device())
+    {
+      return process_blocks(offset, size, const_cast<void *>(buffer),
+                            [](size_t idx, size_t off, size_t len, size_t done, devices::block_device * device,
+                               std::byte * scratch, void * buffer) {
+                              auto const * in = static_cast<std::byte const *>(buffer);
+                              if (off == 0 && len == device->block_size())
+                              {
+                                device->write_block(idx, in + done);
+                              }
+                              else
+                              {
+                                device->read_block(idx, scratch);
+                                kstd::libc::memcpy(scratch + off, in + done, len);
+                                device->write_block(idx, scratch);
+                              }
+                            });
+    }
+    else
+    {
+      kapi::system::panic("[FILESYSTEM] device_file::write called on non-block device.");
+    }
+  }
+
+  auto device_inode::device() const -> kstd::shared_ptr<devices::device> const &
+  {
+    return m_device;
+  }
+
+  auto device_inode::process_blocks(size_t offset, size_t size, void * buffer, block_op op) const -> size_t
+  {
+    if (buffer == nullptr)
+    {
+      kapi::system::panic("[FILESYSTEM] device_file::process_blocks called with null buffer.");
+    }
+
+    if (size == 0)
+    {
+      return 0;
+    }
+
+    auto * block_dev = static_cast<devices::block_device *>(m_device.get());
+    if (block_dev == nullptr)
+    {
+      kapi::system::panic("[FILESYSTEM] device_file: expected block_device.");
+    }
+
+    size_t const block_size = block_dev->block_size();
+    size_t const capacity = block_dev->capacity();
+
+    if (offset >= capacity)
+      return 0;
+    size_t const total_to_process = std::min(size, capacity - offset);
+
+    kstd::vector<std::byte> scratch_buffer{block_size};
+    auto processed = 0uz;
+
+    while (processed < total_to_process)
+    {
+      size_t const absolute_offset = offset + processed;
+      size_t const block_index = absolute_offset / block_size;
+      size_t const in_block_offset = absolute_offset % block_size;
+      size_t const chunk_size = std::min(total_to_process - processed, block_size - in_block_offset);
+
+      op(block_index, in_block_offset, chunk_size, processed, block_dev, scratch_buffer.data(), buffer);
+
+      processed += chunk_size;
+    }
+
+    return processed;
+  }
+}  // namespace filesystem
\ No newline at end of file