child-list.h

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1993-2025 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////
 
#if ! defined (octave_child_list_h)
#define octave_child_list_h 1
 
#include "octave-config.h"
 
#include <csignal>
 
#include <list>
 
#include <sys/types.h>
 
OCTAVE_BEGIN_NAMESPACE(octave)
 
class OCTAVE_API child
{
public:
 
  // Do whatever to handle event for child with PID (might not
  // actually be dead, could just be stopped).  Return true if
  // the list element corresponding to PID should be removed from
  // list.  This function should not call any functions that modify
  // the child_list.
 
  typedef bool (*child_event_handler) (pid_t, int);
 
  child (pid_t pid = -1, child_event_handler f = nullptr)
    : m_pid (pid), m_handler (f), m_have_status (0), m_status (0)
  { }
 
  child (const child&) = default;
 
  child& operator = (const child&) = default;
 
  ~child () = default;
 
  // The process ID of this child.
  pid_t m_pid;
 
  // The function we call if an event happens for this child.
  child_event_handler m_handler;
 
  // Nonzero if this child has stopped or terminated.
  sig_atomic_t m_have_status;
 
  // The m_status of this child; 0 if running, otherwise a m_status value
  // from waitpid.
  int m_status;
};
 
class OCTAVE_API child_list
{
public:
 
  OCTAVE_DEFAULT_CONSTRUCT_COPY_MOVE_DELETE (child_list)
 
  void insert (pid_t pid, child::child_event_handler f);
 
  void remove (pid_t pid);
 
  void reap ();
 
  bool wait ();
 
private:
 
  std::list<child> m_list;
};
 
OCTAVE_END_NAMESPACE(octave)
 
#endif