+++ /dev/null
-/* POSIX compatible signal blocking.
- Copyright (C) 2006-2012 Free Software Foundation, Inc.
- Written by Bruno Haible <bruno@clisp.org>, 2006.
-
- 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/>. */
-
-#include <config.h>
-
-/* Specification. */
-#include <signal.h>
-
-#include <errno.h>
-#include <stdint.h>
-#include <stdlib.h>
-
-#if HAVE_MSVC_INVALID_PARAMETER_HANDLER
-# include "msvc-inval.h"
-#endif
-
-/* We assume that a platform without POSIX signal blocking functions
- also does not have the POSIX sigaction() function, only the
- signal() function. We also assume signal() has SysV semantics,
- where any handler is uninstalled prior to being invoked. This is
- true for native Windows platforms. */
-
-/* We use raw signal(), but also provide a wrapper rpl_signal() so
- that applications can query or change a blocked signal. */
-#undef signal
-
-/* Provide invalid signal numbers as fallbacks if the uncatchable
- signals are not defined. */
-#ifndef SIGKILL
-# define SIGKILL (-1)
-#endif
-#ifndef SIGSTOP
-# define SIGSTOP (-1)
-#endif
-
-/* On native Windows, as of 2008, the signal SIGABRT_COMPAT is an alias
- for the signal SIGABRT. Only one signal handler is stored for both
- SIGABRT and SIGABRT_COMPAT. SIGABRT_COMPAT is not a signal of its own. */
-#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
-# undef SIGABRT_COMPAT
-# define SIGABRT_COMPAT 6
-#endif
-#ifdef SIGABRT_COMPAT
-# define SIGABRT_COMPAT_MASK (1U << SIGABRT_COMPAT)
-#else
-# define SIGABRT_COMPAT_MASK 0
-#endif
-
-typedef void (*handler_t) (int);
-
-#if HAVE_MSVC_INVALID_PARAMETER_HANDLER
-static inline handler_t
-signal_nothrow (int sig, handler_t handler)
-{
- handler_t result;
-
- TRY_MSVC_INVAL
- {
- result = signal (sig, handler);
- }
- CATCH_MSVC_INVAL
- {
- result = SIG_ERR;
- errno = EINVAL;
- }
- DONE_MSVC_INVAL;
-
- return result;
-}
-# define signal signal_nothrow
-#endif
-
-/* Handling of gnulib defined signals. */
-
-#if GNULIB_defined_SIGPIPE
-static handler_t SIGPIPE_handler = SIG_DFL;
-#endif
-
-#if GNULIB_defined_SIGPIPE
-static handler_t
-ext_signal (int sig, handler_t handler)
-{
- switch (sig)
- {
- case SIGPIPE:
- {
- handler_t old_handler = SIGPIPE_handler;
- SIGPIPE_handler = handler;
- return old_handler;
- }
- default: /* System defined signal */
- return signal (sig, handler);
- }
-}
-# undef signal
-# define signal ext_signal
-#endif
-
-int
-sigismember (const sigset_t *set, int sig)
-{
- if (sig >= 0 && sig < NSIG)
- {
- #ifdef SIGABRT_COMPAT
- if (sig == SIGABRT_COMPAT)
- sig = SIGABRT;
- #endif
-
- return (*set >> sig) & 1;
- }
- else
- return 0;
-}
-
-int
-sigemptyset (sigset_t *set)
-{
- *set = 0;
- return 0;
-}
-
-int
-sigaddset (sigset_t *set, int sig)
-{
- if (sig >= 0 && sig < NSIG)
- {
- #ifdef SIGABRT_COMPAT
- if (sig == SIGABRT_COMPAT)
- sig = SIGABRT;
- #endif
-
- *set |= 1U << sig;
- return 0;
- }
- else
- {
- errno = EINVAL;
- return -1;
- }
-}
-
-int
-sigdelset (sigset_t *set, int sig)
-{
- if (sig >= 0 && sig < NSIG)
- {
- #ifdef SIGABRT_COMPAT
- if (sig == SIGABRT_COMPAT)
- sig = SIGABRT;
- #endif
-
- *set &= ~(1U << sig);
- return 0;
- }
- else
- {
- errno = EINVAL;
- return -1;
- }
-}
-
-
-int
-sigfillset (sigset_t *set)
-{
- *set = ((2U << (NSIG - 1)) - 1) & ~ SIGABRT_COMPAT_MASK;
- return 0;
-}
-
-/* Set of currently blocked signals. */
-static volatile sigset_t blocked_set /* = 0 */;
-
-/* Set of currently blocked and pending signals. */
-static volatile sig_atomic_t pending_array[NSIG] /* = { 0 } */;
-
-/* Signal handler that is installed for blocked signals. */
-static void
-blocked_handler (int sig)
-{
- /* Reinstall the handler, in case the signal occurs multiple times
- while blocked. There is an inherent race where an asynchronous
- signal in between when the kernel uninstalled the handler and
- when we reinstall it will trigger the default handler; oh
- well. */
- signal (sig, blocked_handler);
- if (sig >= 0 && sig < NSIG)
- pending_array[sig] = 1;
-}
-
-int
-sigpending (sigset_t *set)
-{
- sigset_t pending = 0;
- int sig;
-
- for (sig = 0; sig < NSIG; sig++)
- if (pending_array[sig])
- pending |= 1U << sig;
- *set = pending;
- return 0;
-}
-
-/* The previous signal handlers.
- Only the array elements corresponding to blocked signals are relevant. */
-static volatile handler_t old_handlers[NSIG];
-
-int
-sigprocmask (int operation, const sigset_t *set, sigset_t *old_set)
-{
- if (old_set != NULL)
- *old_set = blocked_set;
-
- if (set != NULL)
- {
- sigset_t new_blocked_set;
- sigset_t to_unblock;
- sigset_t to_block;
-
- switch (operation)
- {
- case SIG_BLOCK:
- new_blocked_set = blocked_set | *set;
- break;
- case SIG_SETMASK:
- new_blocked_set = *set;
- break;
- case SIG_UNBLOCK:
- new_blocked_set = blocked_set & ~*set;
- break;
- default:
- errno = EINVAL;
- return -1;
- }
- to_unblock = blocked_set & ~new_blocked_set;
- to_block = new_blocked_set & ~blocked_set;
-
- if (to_block != 0)
- {
- int sig;
-
- for (sig = 0; sig < NSIG; sig++)
- if ((to_block >> sig) & 1)
- {
- pending_array[sig] = 0;
- if ((old_handlers[sig] = signal (sig, blocked_handler)) != SIG_ERR)
- blocked_set |= 1U << sig;
- }
- }
-
- if (to_unblock != 0)
- {
- sig_atomic_t received[NSIG];
- int sig;
-
- for (sig = 0; sig < NSIG; sig++)
- if ((to_unblock >> sig) & 1)
- {
- if (signal (sig, old_handlers[sig]) != blocked_handler)
- /* The application changed a signal handler while the signal
- was blocked, bypassing our rpl_signal replacement.
- We don't support this. */
- abort ();
- received[sig] = pending_array[sig];
- blocked_set &= ~(1U << sig);
- pending_array[sig] = 0;
- }
- else
- received[sig] = 0;
-
- for (sig = 0; sig < NSIG; sig++)
- if (received[sig])
- raise (sig);
- }
- }
- return 0;
-}
-
-/* Install the handler FUNC for signal SIG, and return the previous
- handler. */
-handler_t
-rpl_signal (int sig, handler_t handler)
-{
- /* We must provide a wrapper, so that a user can query what handler
- they installed even if that signal is currently blocked. */
- if (sig >= 0 && sig < NSIG && sig != SIGKILL && sig != SIGSTOP
- && handler != SIG_ERR)
- {
- #ifdef SIGABRT_COMPAT
- if (sig == SIGABRT_COMPAT)
- sig = SIGABRT;
- #endif
-
- if (blocked_set & (1U << sig))
- {
- /* POSIX states that sigprocmask and signal are both
- async-signal-safe. This is not true of our
- implementation - there is a slight data race where an
- asynchronous interrupt on signal A can occur after we
- install blocked_handler but before we have updated
- old_handlers for signal B, such that handler A can see
- stale information if it calls signal(B). Oh well -
- signal handlers really shouldn't try to manipulate the
- installed handlers of unrelated signals. */
- handler_t result = old_handlers[sig];
- old_handlers[sig] = handler;
- return result;
- }
- else
- return signal (sig, handler);
- }
- else
- {
- errno = EINVAL;
- return SIG_ERR;
- }
-}
-
-#if GNULIB_defined_SIGPIPE
-/* Raise the signal SIGPIPE. */
-int
-_gl_raise_SIGPIPE (void)
-{
- if (blocked_set & (1U << SIGPIPE))
- pending_array[SIGPIPE] = 1;
- else
- {
- handler_t handler = SIGPIPE_handler;
- if (handler == SIG_DFL)
- exit (128 + SIGPIPE);
- else if (handler != SIG_IGN)
- (*handler) (SIGPIPE);
- }
- return 0;
-}
-#endif
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