signal.h

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#ifndef _LINUX_SIGNAL_H
#define _LINUX_SIGNAL_H

#include <linux/list.h>
#include <uapi/linux/signal.h>

struct task_struct;

/* for sysctl */
extern int print_fatal_signals;
/*
 * Real Time signals may be queued.
 */

struct sigqueue {
    struct list_head list;
    int flags;
    siginfo_t info;
    struct user_struct *user;
};

/* flags values. */
#define SIGQUEUE_PREALLOC   1

struct sigpending {
    struct list_head list;
    sigset_t signal;
};

/*
 * Define some primitives to manipulate sigset_t.
 */

#ifndef __HAVE_ARCH_SIG_BITOPS
#include <linux/bitops.h>

/* We don't use <linux/bitops.h> for these because there is no need to
   be atomic.  */
static inline void sigaddset(sigset_t *set, int _sig)
{
    unsigned long sig = _sig - 1;
    if (_NSIG_WORDS == 1)
        set->sig[0] |= 1UL << sig;
    else
        set->sig[sig / _NSIG_BPW] |= 1UL << (sig % _NSIG_BPW);
}

static inline void sigdelset(sigset_t *set, int _sig)
{
    unsigned long sig = _sig - 1;
    if (_NSIG_WORDS == 1)
        set->sig[0] &= ~(1UL << sig);
    else
        set->sig[sig / _NSIG_BPW] &= ~(1UL << (sig % _NSIG_BPW));
}

static inline int sigismember(sigset_t *set, int _sig)
{
    unsigned long sig = _sig - 1;
    if (_NSIG_WORDS == 1)
        return 1 & (set->sig[0] >> sig);
    else
        return 1 & (set->sig[sig / _NSIG_BPW] >> (sig % _NSIG_BPW));
}

static inline int sigfindinword(unsigned long word)
{
    return ffz(~word);
}

#endif /* __HAVE_ARCH_SIG_BITOPS */

static inline int sigisemptyset(sigset_t *set)
{
    extern void _NSIG_WORDS_is_unsupported_size(void);
    switch (_NSIG_WORDS) {
    case 4:
        return (set->sig[3] | set->sig[2] |
            set->sig[1] | set->sig[0]) == 0;
    case 2:
        return (set->sig[1] | set->sig[0]) == 0;
    case 1:
        return set->sig[0] == 0;
    default:
        _NSIG_WORDS_is_unsupported_size();
        return 0;
    }
}

#define sigmask(sig)    (1UL << ((sig) - 1))

#ifndef __HAVE_ARCH_SIG_SETOPS
#include <linux/string.h>

#define _SIG_SET_BINOP(name, op)                    \
static inline void name(sigset_t *r, const sigset_t *a, const sigset_t *b) \
{                                   \
    extern void _NSIG_WORDS_is_unsupported_size(void);      \
    unsigned long a0, a1, a2, a3, b0, b1, b2, b3;           \
                                    \
    switch (_NSIG_WORDS) {                      \
        case 4:                         \
        a3 = a->sig[3]; a2 = a->sig[2];             \
        b3 = b->sig[3]; b2 = b->sig[2];             \
        r->sig[3] = op(a3, b3);                 \
        r->sig[2] = op(a2, b2);                 \
        case 2:                         \
        a1 = a->sig[1]; b1 = b->sig[1];             \
        r->sig[1] = op(a1, b1);                 \
        case 1:                         \
        a0 = a->sig[0]; b0 = b->sig[0];             \
        r->sig[0] = op(a0, b0);                 \
        break;                          \
        default:                            \
        _NSIG_WORDS_is_unsupported_size();          \
    }                               \
}

#define _sig_or(x,y)    ((x) | (y))
_SIG_SET_BINOP(sigorsets, _sig_or)

#define _sig_and(x,y)   ((x) & (y))
_SIG_SET_BINOP(sigandsets, _sig_and)

#define _sig_andn(x,y)  ((x) & ~(y))
_SIG_SET_BINOP(sigandnsets, _sig_andn)

#undef _SIG_SET_BINOP
#undef _sig_or
#undef _sig_and
#undef _sig_andn

#define _SIG_SET_OP(name, op)                       \
static inline void name(sigset_t *set)                  \
{                                   \
    extern void _NSIG_WORDS_is_unsupported_size(void);      \
                                    \
    switch (_NSIG_WORDS) {                      \
        case 4: set->sig[3] = op(set->sig[3]);          \
            set->sig[2] = op(set->sig[2]);          \
        case 2: set->sig[1] = op(set->sig[1]);          \
        case 1: set->sig[0] = op(set->sig[0]);          \
            break;                      \
        default:                            \
        _NSIG_WORDS_is_unsupported_size();          \
    }                               \
}

#define _sig_not(x) (~(x))
_SIG_SET_OP(signotset, _sig_not)

#undef _SIG_SET_OP
#undef _sig_not

static inline void sigemptyset(sigset_t *set)
{
    switch (_NSIG_WORDS) {
    default:
        memset(set, 0, sizeof(sigset_t));
        break;
    case 2: set->sig[1] = 0;
    case 1: set->sig[0] = 0;
        break;
    }
}

static inline void sigfillset(sigset_t *set)
{
    switch (_NSIG_WORDS) {
    default:
        memset(set, -1, sizeof(sigset_t));
        break;
    case 2: set->sig[1] = -1;
    case 1: set->sig[0] = -1;
        break;
    }
}

/* Some extensions for manipulating the low 32 signals in particular.  */

static inline void sigaddsetmask(sigset_t *set, unsigned long mask)
{
    set->sig[0] |= mask;
}

static inline void sigdelsetmask(sigset_t *set, unsigned long mask)
{
    set->sig[0] &= ~mask;
}

static inline int sigtestsetmask(sigset_t *set, unsigned long mask)
{
    return (set->sig[0] & mask) != 0;
}

static inline void siginitset(sigset_t *set, unsigned long mask)
{
    set->sig[0] = mask;
    switch (_NSIG_WORDS) {
    default:
        memset(&set->sig[1], 0, sizeof(long)*(_NSIG_WORDS-1));
        break;
    case 2: set->sig[1] = 0;
    case 1: ;
    }
}

static inline void siginitsetinv(sigset_t *set, unsigned long mask)
{
    set->sig[0] = ~mask;
    switch (_NSIG_WORDS) {
    default:
        memset(&set->sig[1], -1, sizeof(long)*(_NSIG_WORDS-1));
        break;
    case 2: set->sig[1] = -1;
    case 1: ;
    }
}

#endif /* __HAVE_ARCH_SIG_SETOPS */

static inline void init_sigpending(struct sigpending *sig)
{
    sigemptyset(&sig->signal);
    INIT_LIST_HEAD(&sig->list);
}

extern void flush_sigqueue(struct sigpending *queue);

/* Test if 'sig' is valid signal. Use this instead of testing _NSIG directly */
static inline int valid_signal(unsigned long sig)
{
    return sig <= _NSIG ? 1 : 0;
}

struct timespec;
struct pt_regs;

extern int next_signal(struct sigpending *pending, sigset_t *mask);
extern int do_send_sig_info(int sig, struct siginfo *info,
                struct task_struct *p, bool group);
extern int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p);
extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *);
extern long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig,
                 siginfo_t *info);
extern long do_sigpending(void __user *, unsigned long);
extern int do_sigtimedwait(const sigset_t *, siginfo_t *,
                const struct timespec *);
extern int sigprocmask(int, sigset_t *, sigset_t *);
extern void set_current_blocked(sigset_t *);
extern void __set_current_blocked(const sigset_t *);
extern int show_unhandled_signals;
extern int sigsuspend(sigset_t *);

extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie);
extern void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka, struct pt_regs *regs, int stepping);
extern void exit_signals(struct task_struct *tsk);

extern struct kmem_cache *sighand_cachep;

int unhandled_signal(struct task_struct *tsk, int sig);

/*
 * In POSIX a signal is sent either to a specific thread (Linux task)
 * or to the process as a whole (Linux thread group).  How the signal
 * is sent determines whether it's to one thread or the whole group,
 * which determines which signal mask(s) are involved in blocking it
 * from being delivered until later.  When the signal is delivered,
 * either it's caught or ignored by a user handler or it has a default
 * effect that applies to the whole thread group (POSIX process).
 *
 * The possible effects an unblocked signal set to SIG_DFL can have are:
 *   ignore - Nothing Happens
 *   terminate  - kill the process, i.e. all threads in the group,
 *        similar to exit_group.  The group leader (only) reports
 *        WIFSIGNALED status to its parent.
 *   coredump   - write a core dump file describing all threads using
 *        the same mm and then kill all those threads
 *   stop   - stop all the threads in the group, i.e. TASK_STOPPED state
 *
 * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
 * Other signals when not blocked and set to SIG_DFL behaves as follows.
 * The job control signals also have other special effects.
 *
 *  +--------------------+------------------+
 *  |  POSIX signal      |  default action  |
 *  +--------------------+------------------+
 *  |  SIGHUP            |  terminate   |
 *  |  SIGINT            |  terminate   |
 *  |  SIGQUIT           |  coredump    |
 *  |  SIGILL            |  coredump    |
 *  |  SIGTRAP           |  coredump    |
 *  |  SIGABRT/SIGIOT    |  coredump    |
 *  |  SIGBUS            |  coredump    |
 *  |  SIGFPE            |  coredump    |
 *  |  SIGKILL           |  terminate(+)    |
 *  |  SIGUSR1           |  terminate   |
 *  |  SIGSEGV           |  coredump    |
 *  |  SIGUSR2           |  terminate   |
 *  |  SIGPIPE           |  terminate   |
 *  |  SIGALRM           |  terminate   |
 *  |  SIGTERM           |  terminate   |
 *  |  SIGCHLD           |  ignore      |
 *  |  SIGCONT           |  ignore(*)   |
 *  |  SIGSTOP           |  stop(*)(+)      |
 *  |  SIGTSTP           |  stop(*)     |
 *  |  SIGTTIN           |  stop(*)     |
 *  |  SIGTTOU           |  stop(*)     |
 *  |  SIGURG            |  ignore      |
 *  |  SIGXCPU           |  coredump    |
 *  |  SIGXFSZ           |  coredump    |
 *  |  SIGVTALRM         |  terminate   |
 *  |  SIGPROF           |  terminate   |
 *  |  SIGPOLL/SIGIO     |  terminate   |
 *  |  SIGSYS/SIGUNUSED  |  coredump    |
 *  |  SIGSTKFLT         |  terminate   |
 *  |  SIGWINCH          |  ignore      |
 *  |  SIGPWR            |  terminate   |
 *  |  SIGRTMIN-SIGRTMAX |  terminate       |
 *  +--------------------+------------------+
 *  |  non-POSIX signal  |  default action  |
 *  +--------------------+------------------+
 *  |  SIGEMT            |  coredump    |
 *  +--------------------+------------------+
 *
 * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
 * (*) Special job control effects:
 * When SIGCONT is sent, it resumes the process (all threads in the group)
 * from TASK_STOPPED state and also clears any pending/queued stop signals
 * (any of those marked with "stop(*)").  This happens regardless of blocking,
 * catching, or ignoring SIGCONT.  When any stop signal is sent, it clears
 * any pending/queued SIGCONT signals; this happens regardless of blocking,
 * catching, or ignored the stop signal, though (except for SIGSTOP) the
 * default action of stopping the process may happen later or never.
 */

#ifdef SIGEMT
#define SIGEMT_MASK rt_sigmask(SIGEMT)
#else
#define SIGEMT_MASK 0
#endif

#if SIGRTMIN > BITS_PER_LONG
#define rt_sigmask(sig) (1ULL << ((sig)-1))
#else
#define rt_sigmask(sig) sigmask(sig)
#endif
#define siginmask(sig, mask) (rt_sigmask(sig) & (mask))

#define SIG_KERNEL_ONLY_MASK (\
    rt_sigmask(SIGKILL)   |  rt_sigmask(SIGSTOP))

#define SIG_KERNEL_STOP_MASK (\
    rt_sigmask(SIGSTOP)   |  rt_sigmask(SIGTSTP)   | \
    rt_sigmask(SIGTTIN)   |  rt_sigmask(SIGTTOU)   )

#define SIG_KERNEL_COREDUMP_MASK (\
        rt_sigmask(SIGQUIT)   |  rt_sigmask(SIGILL)    | \
    rt_sigmask(SIGTRAP)   |  rt_sigmask(SIGABRT)   | \
        rt_sigmask(SIGFPE)    |  rt_sigmask(SIGSEGV)   | \
    rt_sigmask(SIGBUS)    |  rt_sigmask(SIGSYS)    | \
        rt_sigmask(SIGXCPU)   |  rt_sigmask(SIGXFSZ)   | \
    SIGEMT_MASK                    )

#define SIG_KERNEL_IGNORE_MASK (\
        rt_sigmask(SIGCONT)   |  rt_sigmask(SIGCHLD)   | \
    rt_sigmask(SIGWINCH)  |  rt_sigmask(SIGURG)    )

#define sig_kernel_only(sig) \
    (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_ONLY_MASK))
#define sig_kernel_coredump(sig) \
    (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_COREDUMP_MASK))
#define sig_kernel_ignore(sig) \
    (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_IGNORE_MASK))
#define sig_kernel_stop(sig) \
    (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_STOP_MASK))

#define sig_user_defined(t, signr) \
    (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) &&  \
     ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))

#define sig_fatal(t, signr) \
    (!siginmask(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
     (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)

void signals_init(void);

#endif /* _LINUX_SIGNAL_H */