| /* Support for ignoring signals. |
| |
| Copyright (C) 2021-2024 Free Software Foundation, Inc. |
| |
| This file is part of GDB. |
| |
| This program 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. |
| |
| This program 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 this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| #ifndef SCOPED_IGNORE_SIGNAL_H |
| #define SCOPED_IGNORE_SIGNAL_H |
| |
| #include <signal.h> |
| |
| /* RAII class used to ignore a signal in a scope. If sigprocmask is |
| supported, then the signal is only ignored by the calling thread. |
| Otherwise, the signal disposition is set to SIG_IGN, which affects |
| the whole process. If ConsumePending is true, the destructor |
| consumes a pending Sig. SIGPIPE for example is queued on the |
| thread even if blocked at the time the pipe is written to. SIGTTOU |
| OTOH is not raised at all if the thread writing to the terminal has |
| it blocked. Because SIGTTOU is sent to the whole process instead |
| of to a specific thread, consuming a pending SIGTTOU in the |
| destructor could consume a signal raised due to actions done by |
| some other thread. */ |
| |
| template <int Sig, bool ConsumePending> |
| class scoped_ignore_signal |
| { |
| public: |
| scoped_ignore_signal () |
| { |
| #ifdef HAVE_SIGPROCMASK |
| sigset_t set, old_state; |
| |
| sigemptyset (&set); |
| sigaddset (&set, Sig); |
| sigprocmask (SIG_BLOCK, &set, &old_state); |
| m_was_blocked = sigismember (&old_state, Sig); |
| #else |
| m_osig = signal (Sig, SIG_IGN); |
| #endif |
| } |
| |
| ~scoped_ignore_signal () |
| { |
| #ifdef HAVE_SIGPROCMASK |
| if (!m_was_blocked) |
| { |
| sigset_t set; |
| |
| sigemptyset (&set); |
| sigaddset (&set, Sig); |
| |
| /* If we got a pending Sig signal, consume it before |
| unblocking. */ |
| if (ConsumePending) |
| { |
| #ifdef HAVE_SIGTIMEDWAIT |
| const timespec zero_timeout = {}; |
| |
| sigtimedwait (&set, nullptr, &zero_timeout); |
| #else |
| sigset_t pending; |
| |
| sigpending (&pending); |
| if (sigismember (&pending, Sig)) |
| { |
| int sig_found; |
| |
| sigwait (&set, &sig_found); |
| gdb_assert (sig_found == Sig); |
| } |
| #endif |
| } |
| |
| sigprocmask (SIG_UNBLOCK, &set, nullptr); |
| } |
| #else |
| signal (Sig, m_osig); |
| #endif |
| } |
| |
| DISABLE_COPY_AND_ASSIGN (scoped_ignore_signal); |
| |
| private: |
| #ifdef HAVE_SIGPROCMASK |
| bool m_was_blocked; |
| #else |
| sighandler_t m_osig; |
| #endif |
| }; |
| |
| struct scoped_ignore_signal_nop |
| { |
| /* Note, these can't both be "= default", because otherwise the |
| compiler warns that variables of this type are not used. */ |
| scoped_ignore_signal_nop () |
| {} |
| ~scoped_ignore_signal_nop () |
| {} |
| DISABLE_COPY_AND_ASSIGN (scoped_ignore_signal_nop); |
| }; |
| |
| #ifdef SIGPIPE |
| using scoped_ignore_sigpipe = scoped_ignore_signal<SIGPIPE, true>; |
| #else |
| using scoped_ignore_sigpipe = scoped_ignore_signal_nop; |
| #endif |
| |
| #endif /* SCOPED_IGNORE_SIGNAL_H */ |