Merge pull request #66 from 0xf00sec/patch-2

feat: `T.Value` (ErrorOr.h)

1 files changed, 140 insertions, 0 deletions

diff --git a/dev/kernel/FSKit/Ext2+IFS.h b/dev/kernel/FSKit/Ext2+IFS.h
new file mode 100644
index 00000000..d73ae43c
--- /dev/null
+++ b/dev/kernel/FSKit/Ext2+IFS.h
@@ -0,0 +1,140 @@
+#pragma once
+
+#include <FSKit/Ext2.h>
+#include <KernelKit/DriveMgr.h>
+#include <KernelKit/HeapMgr.h>
+#include <KernelKit/KPC.h>
+#include <NeKit/ErrorOr.h>
+#include <NeKit/KernelPanic.h>
+#include <NeKit/Utils.h>
+
+namespace Kernel::Ext2 {
+/// @brief Context for an EXT2 filesystem on a given drive
+struct Ext2Context {
+  Kernel::DriveTrait* drive{nullptr};
+  EXT2_SUPER_BLOCK*   superblock{nullptr};
+
+  /// @brief context with a drive
+  Ext2Context(Kernel::DriveTrait* drv) : drive(drv) {}
+
+  /// @brief Clean up
+  ~Ext2Context() {
+    if (superblock) {
+      Kernel::mm_free_ptr(superblock);
+      superblock = nullptr;
+    }
+  }
+
+  Ext2Context(const Ext2Context&) = delete;
+  Ext2Context& operator=(const Ext2Context&) = delete;
+
+  Ext2Context(Ext2Context&& other) noexcept : drive(other.drive), superblock(other.superblock) {
+    other.drive      = nullptr;
+    other.superblock = nullptr;
+  }
+
+  Ext2Context& operator=(Ext2Context&& other) noexcept {
+    if (this != &other) {
+      if (superblock) {
+        Kernel::mm_free_ptr(superblock);
+      }
+      drive            = other.drive;
+      superblock       = other.superblock;
+      other.drive      = nullptr;
+      other.superblock = nullptr;
+    }
+    return *this;
+  }
+
+  Kernel::SizeT LeakBlockSize() const {
+    if (!superblock) return kExt2FSBlockSizeBase;
+    return kExt2FSBlockSizeBase << superblock->fLogBlockSize;
+  }
+
+  BOOL operator bool() { return superblock != nullptr; }
+};
+
+/// ======================================================================= ///
+/// IFS FUNCTIONS
+/// ======================================================================= ///
+
+inline bool ext2_read_block(Kernel::DriveTrait* drv, Kernel::UInt32 lba, void* buffer,
+                            Kernel::UInt32 size) {
+  if (!drv || !buffer) return false;
+
+  Kernel::DriveTrait::DrivePacket pkt{};
+  pkt.fPacketContent = buffer;
+  pkt.fPacketSize    = size;
+  pkt.fPacketLba     = lba;
+  drv->fInput(pkt);
+
+  return pkt.fPacketGood;
+}
+
+inline bool ext2_write_block(Kernel::DriveTrait* drv, Kernel::UInt32 lba, const void* buffer,
+                             Kernel::UInt32 size) {
+  if (!drv || !buffer) return false;
+
+  Kernel::DriveTrait::DrivePacket pkt{};
+  pkt.fPacketContent = const_cast<void*>(buffer);
+  pkt.fPacketSize    = size;
+  pkt.fPacketLba     = lba;
+  drv->fOutput(pkt);
+  return pkt.fPacketGood;
+}
+
+inline Kernel::ErrorOr<EXT2_SUPER_BLOCK*> ext2_load_superblock(Ext2Context* ctx) {
+  if (!ctx || !ctx->drive) return Kernel::ErrorOr<EXT2_SUPER_BLOCK*>(Kernel::kErrorInvalidData);
+
+  auto buf = Kernel::mm_alloc_ptr(sizeof(EXT2_SUPER_BLOCK), true, false);
+  if (!buf) return Kernel::ErrorOr<EXT2_SUPER_BLOCK*>(Kernel::kErrorHeapOutOfMemory);
+
+  Kernel::UInt32 blockLba = kExt2FSSuperblockOffset / ctx->drive->fSectorSz;
+
+  if (!ext2_read_block(ctx->drive, blockLba, buf, sizeof(EXT2_SUPER_BLOCK))) {
+    Kernel::mm_free_ptr(buf);
+    return Kernel::ErrorOr<EXT2_SUPER_BLOCK*>(Kernel::kErrorDisk);
+  }
+
+  auto sb = reinterpret_cast<EXT2_SUPER_BLOCK*>(buf);
+  if (sb->fMagic != kExt2FSMagic) {
+    Kernel::mm_free_ptr(buf);
+    return Kernel::ErrorOr<EXT2_SUPER_BLOCK*>(Kernel::kErrorInvalidData);
+  }
+
+  ctx->superblock = sb;
+  return Kernel::ErrorOr<EXT2_SUPER_BLOCK*>(sb);
+}
+
+// Load inode
+inline Kernel::ErrorOr<Ext2Node*> ext2_load_inode(Ext2Context* ctx, Kernel::UInt32 inodeNumber) {
+  if (!ctx || !ctx->superblock) return Kernel::ErrorOr<Ext2Node*>(Kernel::kErrorInvalidData);
+
+  auto nodePtr = Kernel::mm_alloc_ptr(sizeof(Ext2Node), true, false);
+  if (!nodePtr) return Kernel::ErrorOr<Ext2Node*>(Kernel::kErrorHeapOutOfMemory);
+
+  auto ext2Node         = reinterpret_cast<Ext2Node*>(nodePtr);
+  ext2Node->inodeNumber = inodeNumber;
+
+  // Compute block group and index within group
+  Kernel::UInt32 inodesPerGroup = ctx->superblock->fInodesPerGroup;
+  Kernel::UInt32 group          = (inodeNumber - 1) / inodesPerGroup;
+  Kernel::UInt32 index          = (inodeNumber - 1) % inodesPerGroup;
+
+  // dummy: just offset first inode
+  Kernel::UInt32 inodeTableBlock = ctx->superblock->fFirstInode + group;
+
+  if (!ext2_read_block(ctx->drive, inodeTableBlock, &ext2Node->inode, sizeof(EXT2_INODE))) {
+    Kernel::mm_free_ptr(nodePtr);
+    return Kernel::ErrorOr<Ext2Node*>(Kernel::kErrorDisk);
+  }
+
+  ext2Node->cursor = 0;
+  return Kernel::ErrorOr<Ext2Node*>(ext2Node);
+}
+
+inline Kernel::UInt32 inode_offset(const Ext2Context* ctx, Kernel::UInt32 inodeNumber) {
+  if (!ctx || !ctx->superblock) return 0;
+  return ((inodeNumber - 1) % ctx->superblock->fInodesPerGroup) * ctx->superblock->fInodeSize;
+}
+}  // namespace Kernel::Ext2