gdbsupport/scoped_ignore_sigttou.h

   1 /* Support for ignoring SIGTTOU.
   2
   3    Copyright (C) 2003-2023 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef SCOPED_IGNORE_SIGTTOU_H
  21 #define SCOPED_IGNORE_SIGTTOU_H
  22
  23 #include "gdbsupport/scoped_ignore_signal.h"
  24 #include "gdbsupport/job-control.h"
  25
  26 #ifdef SIGTTOU
  27
  28 /* Simple wrapper that allows lazy initialization / destruction of T.
  29    Slightly more efficient than gdb::optional, because it doesn't
  30    carry storage to track whether the object has been initialized.  */
  31 template<typename T>
  32 class lazy_init
  33 {
  34 public:
  35   void emplace ()
  36   {
  37     new (&m_u.obj) T ();
  38   }
  39
  40   void reset ()
  41   {
  42     m_u.obj.~T ();
  43   }
  44
  45 private:
  46   union u
  47   {
  48     /* Must define ctor/dtor if T has non-trivial ctor/dtor.  */
  49     u () {}
  50     ~u () {}
  51
  52     T obj;
  53   } m_u;
  54 };
  55
  56 /* RAII class used to ignore SIGTTOU in a scope.  This isn't simply
  57    scoped_ignore_signal<SIGTTOU> because we want to check the
  58    `job_control' global.  */
  59
  60 class scoped_ignore_sigttou
  61 {
  62 public:
  63   scoped_ignore_sigttou ()
  64   {
  65     if (job_control)
  66       m_ignore_signal.emplace ();
  67   }
  68
  69   ~scoped_ignore_sigttou ()
  70   {
  71     if (job_control)
  72       m_ignore_signal.reset ();
  73   }
  74
  75   DISABLE_COPY_AND_ASSIGN (scoped_ignore_sigttou);
  76
  77 private:
  78   lazy_init<scoped_ignore_signal<SIGTTOU, false>> m_ignore_signal;
  79 };
  80
  81 #else
  82
  83 using scoped_ignore_sigttou = scoped_ignore_signal_nop;
  84
  85 #endif
  86
  87 #endif /* SCOPED_IGNORE_SIGTTOU_H */