Method Clone

src/task/clone.cpp:13–215

#include "virtual_memory.hpp"

auto TaskManager::Clone(uint64_t flags, void* user_stack, int* parent_tid,
                        int* child_tid, void* tls,
                        cpu_io::TrapContext& parent_context) -> Expected<Pid> {
  auto* parent = GetCurrentTask();
  if (!parent) {
    klog::Err("Clone: No current task");
    return std::unexpected(Error(ErrorCode::kTaskNoCurrentTask));
  }

  // 验证克隆标志的合法性
  // 如果设置了 kCloneThread，必须同时设置 kCloneVm, kCloneFiles, kCloneSighand
  if ((flags & clone_flag::kThread) &&
      (!(flags & clone_flag::kVm) || !(flags & clone_flag::kFiles) ||
       !(flags & clone_flag::kSighand))) {
    klog::Warn(
        "Clone: kCloneThread requires kCloneVm, kCloneFiles, kCloneSighand");
    // 自动补全必需的标志
    flags |= (clone_flag::kVm | clone_flag::kFiles | clone_flag::kSighand);
  }

  // 分配新的 PID
  Pid new_pid = AllocatePid();
  if (new_pid == 0) {
    klog::Err("Clone: Failed to allocate PID");
    return std::unexpected(Error(ErrorCode::kTaskPidAllocationFailed));
  }

  // 创建子任务控制块
  auto child_ptr = kstd::make_unique<TaskControlBlock>();
  if (!child_ptr) {
    klog::Err("Clone: Failed to allocate child task");
    return std::unexpected(Error(ErrorCode::kTaskAllocationFailed));
  }
  auto* child = child_ptr.get();
  // Default ctor leaves FSM in set_states-but-not-started state.
  // Start it so get_state_id() returns kUnInit instead of deref null.
  child->fsm.Start();

  // 基本字段设置
  child->pid = new_pid;
  child->name = parent->name;
  child->policy = parent->policy;
  child->sched_info = parent->sched_info;

  // 设置父进程 ID
  if (flags & clone_flag::kParent) {
    // 保持与父进程相同的父进程
    child->aux->parent_pid = parent->aux->parent_pid;
  } else {
    child->aux->parent_pid = parent->pid;
  }

  // 处理线程组 ID (TGID)
  if (flags & clone_flag::kThread) {
    // 创建线程: 共享线程组
    child->aux->tgid = parent->aux->tgid;
    child->aux->pgid = parent->aux->pgid;
    child->aux->sid = parent->aux->sid;