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thodg/cgminer/lib/sigprocmask.c
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- lib/sigprocmask.c
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/* POSIX compatible signal blocking. Copyright (C) 2006-2011 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> /* 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 Woe32 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); /* 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); } } # 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 SIG. */ int rpl_raise (int sig) # undef raise { switch (sig) { case SIGPIPE: if (blocked_set & (1U << sig)) pending_array[sig] = 1; else { handler_t handler = SIGPIPE_handler; if (handler == SIG_DFL) exit (128 + SIGPIPE); else if (handler != SIG_IGN) (*handler) (sig); } return 0; default: /* System defined signal */ return raise (sig); } } #endif