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SIGNAL(9) FreeBSD Kernel Developer's Manual SIGNAL(9)
NAME
signal, SIGADDSET, SIGDELSET, SETEMPTYSET, SIGFILLSET, SIGISMEMBER,
SIGISEMPTY, SIGNOTEMPTY, SIGSETEQ, SIGSETNEQ, SIGSETOR, SIGSETAND,
SIGSETNAND, SIGSETCANTMASK, SIG_STOPSIGMASK, SIG_CONTSIGMASK, SIGPENDING,
cursig, execsigs, issignal, killproc, pgsigio, postsig, sigexit, siginit,
signotify, trapsignal - kernel signal functions
SYNOPSIS
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/signalvar.h>
void
SIGADDSET(sigset_t set, int signo);
void
SIGDELSET(sigset_t set, int signo);
void
SIGEMPTYSET(sigset_t set);
void
SIGFILLSET(sigset_t set);
int
SIGISMEMBER(sigset_t set, int signo);
int
SIGISEMPTY(sigset_t set);
int
SIGNOTEMPTY(sigset_t set);
int
SIGSETEQ(sigset_t set1, sigset_t set2);
int
SIGSETNEQ(sigset_t set1, sigset_t set2);
void
SIGSETOR(sigset_t set1, sigset_t set2);
void
SIGSETAND(sigset_t set1, sigset_t set2);
void
SIGSETNAND(sigset_t set1, sigset_t set2);
void
SIG_CANTMASK(sigset_t set);
void
SIG_STOPSIGMASK(sigset_t set);
void
SIG_CONTSIGMASK(sigset_t set);
execsigs(struct proc *p);
int
issignal(struct thread *td);
void
killproc(struct proc *p, char *why);
void
pgsigio(struct sigio **sigiop, int sig, int checkctty);
void
postsig(int sig);
void
sigexit(struct thread *td, int signum);
void
siginit(struct proc *p);
void
signotify(struct thread *td);
void
trapsignal(struct thread *td, int sig, u_long code);
DESCRIPTION
The SIGADDSET() macro adds signo to set. No effort is made to ensure
that signo is a valid signal number.
The SIGDELSET() macro removes signo from set. No effort is made to
ensure that signo is a valid signal number.
The SIGEMPTYSET() macro clears all signals in set.
The SIGFILLSET() macro sets all signals in set.
The SIGISMEMBER() macro determines if signo is set in set.
The SIGISEMPTY() macro determines if set does not have any signals set.
The SIGNOTEMPTY() macro determines if set has any signals set.
The SIGSETEQ() macro determines if two signal sets are equal; that is,
the same signals are set in both.
The SIGSETNEQ() macro determines if two signal sets differ; that is, if
any signal set in one is not set in the other.
The SIGSETOR() macro ORs the signals set in set2 into set1.
The SIGSETAND() macro ANDs the signals set in set2 into set1.
The SIGSETNAND() macro NANDs the signals set in set2 into set1.
The SIG_CANTMASK() macro clears the SIGKILL and SIGSTOP signals from set.
These two signals cannot be blocked or caught and SIG_CANTMASK() is used
in code where signals are manipulated to ensure this policy is enforced.
The SIGPENDING() macro determines if the given process has any pending
signals that are not masked. If the process has a pending signal and the
process is currently being traced, SIGPENDING() will return true even if
the signal is masked.
The cursig() function returns the signal number that should be delivered
to process td->td_proc. If there are no signals pending, zero is
returned.
The execsigs() function resets the signal set and signal stack of a
process in preparation for an execve(2). The process lock for p must be
held before execsigs() is called.
The issignal() function determines if there are any pending signals for
process td->td_proc that should be caught, or cause this process to
terminate or interrupt its current system call. If process td->td_proc
is currently being traced, ignored signals will be handled and the
process is always stopped. Stop signals are handled and cleared right
away by issignal() unless the process is a member of an orphaned process
group and the stop signal originated from a TTY. The process spin lock
for td->td_proc may be acquired and released. The sigacts structure
td->td_proc->p_sigacts must be locked before calling issignal() and may
be released and reacquired during the call. The process lock for
td->td_proc must be acquired before calling issignal() and may be
released and reacquired during the call. Default signal actions are not
taken for system processes and init.
The killproc() function delivers SIGKILL to p. why is logged as the
reason why the process was killed.
The pgsigio() function sends the signal sig to the process or process
group sigiop->sio_pgid. If checkctty is non-zero, the signal is only
delivered to processes in the process group that have a controlling
terminal. If sigiop->sio_pgid is for a process (> 0), the lock for
sigiop->sio_proc is acquired and released. If sigiop->sio_pgid is for a
process group (< 0), the process group lock for sigiop->sio_pgrp is
acquired and released. The lock sigio_lock is acquired and released.
The postsig() function handles the actual delivery of the signal sig.
postsig() is called from ast() after the kernel has been notified that a
signal should be delivered (via a call to signotify(), which causes the
flag PS_NEEDSIGCHK to be set). The process lock for process that owns
curthread must be held before postsig() is called, and the current
process cannot be 0. The lock for the p_sigacts field of the current
process must be held before postsig() is called, and may be released and
reacquired.
The sigexit() function causes the process that owns td to exit with a
return value of signal number sig. If required, the process will dump
core. The process lock for the process that owns td must be held before
sigexit() is called.
The siginit() function is called during system initialization to cause
every signal with a default property of SA_IGNORE (except SIGCONT) to be
ignored by p. The process lock for p is acquired and released, as is the
lock for sigacts structure p->p_sigacts. The only process that siginit()
is ever called for is proc0.
can be delivered immediately, trapsignal() will deliver it directly;
otherwise, trapsignal() will call psignal(9) to cause the signal to be
delivered. The process lock for td->td_proc is acquired and released.
The lock for the p_sigacts field of td->td_proc is acquired and released.
RETURN VALUES
The SIGISMEMBER(), SIGISEMPTY(), SIGNOTEMPTY(), SIGSETEQ(), SIGSETNEQ(),
and SIGPENDING() macros all return non-zero (true) if the condition they
are checking is found to be true; otherwise, zero (false) is returned.
The cursig() function returns either a valid signal number or zero.
issignal() returns either a valid signal number or zero.
SEE ALSO
pgsignal(9), psignal(9)
AUTHORS
This manual page was written by Chad David <davidc@FreeBSD.org>.
FreeBSD 14.0-RELEASE-p11 July 14, 2023 FreeBSD 14.0-RELEASE-p11