проверять и изменять заблокированные сигналы (examine and change blocked signals)
Имя (Name)
sigprocmask, rt_sigprocmask - examine and change blocked signals
Синопсис (Synopsis)
#include <signal.h>
/* Prototype for the glibc wrapper function */
int sigprocmask(int how, const sigset_t *restrict set,
sigset_t *restrict oldset);
#include <signal.h> /* Definition of SIG_* constants */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
/* Prototype for the underlying system call */
int syscall(SYS_rt_sigprocmask, int how, const kernel_sigset_t *set,
kernel_sigset_t *oldset, size_t sigsetsize);
/* Prototype for the legacy system call (deprecated) */
int syscall(SYS_sigprocmask, int how, const old_kernel_sigset_t *set,
old_kernel_sigset_t *oldset);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
sigprocmask():
_POSIX_C_SOURCE
Описание (Description)
sigprocmask() is used to fetch and/or change the signal mask of
the calling thread. The signal mask is the set of signals whose
delivery is currently blocked for the caller (see also signal(7)
for more details).
The behavior of the call is dependent on the value of how, as
follows.
SIG_BLOCK
The set of blocked signals is the union of the current set
and the set argument.
SIG_UNBLOCK
The signals in set are removed from the current set of
blocked signals. It is permissible to attempt to unblock
a signal which is not blocked.
SIG_SETMASK
The set of blocked signals is set to the argument set.
If oldset is non-NULL, the previous value of the signal mask is
stored in oldset.
If set is NULL, then the signal mask is unchanged (i.e., how is
ignored), but the current value of the signal mask is
nevertheless returned in oldset (if it is not NULL).
A set of functions for modifying and inspecting variables of type
sigset_t ("signal sets") is described in sigsetops(3).
The use of sigprocmask() is unspecified in a multithreaded
process; see pthread_sigmask(3).
Возвращаемое значение (Return value)
sigprocmask() returns 0 on success. On failure, -1 is returned
and errno is set to indicate the error.
Ошибки (Error)
EFAULT The set or oldset argument points outside the process's
allocated address space.
EINVAL Either the value specified in how was invalid or the
kernel does not support the size passed in sigsetsize.
Стандарты (Conforming to)
POSIX.1-2001, POSIX.1-2008.
Примечание (Note)
It is not possible to block SIGKILL or SIGSTOP. Attempts to do
so are silently ignored.
Each of the threads in a process has its own signal mask.
A child created via fork(2) inherits a copy of its parent's
signal mask; the signal mask is preserved across execve(2).
If SIGBUS, SIGFPE, SIGILL, or SIGSEGV are generated while they
are blocked, the result is undefined, unless the signal was
generated by kill(2), sigqueue(3), or raise(3).
See sigsetops(3) for details on manipulating signal sets.
Note that it is permissible (although not very useful) to specify
both set and oldset as NULL.
C library/kernel differences
The kernel's definition of sigset_t differs in size from that
used by the C library. In this manual page, the former is
referred to as kernel_sigset_t (it is nevertheless named sigset_t
in the kernel sources).
The glibc wrapper function for sigprocmask() silently ignores
attempts to block the two real-time signals that are used
internally by the NPTL threading implementation. See nptl(7) for
details.
The original Linux system call was named sigprocmask(). However,
with the addition of real-time signals in Linux 2.2, the fixed-
size, 32-bit sigset_t (referred to as old_kernel_sigset_t in this
manual page) type supported by that system call was no longer fit
for purpose. Consequently, a new system call, rt_sigprocmask(),
was added to support an enlarged sigset_t type (referred to as
kernel_sigset_t in this manual page). The new system call takes
a fourth argument, size_t sigsetsize, which specifies the size in
bytes of the signal sets in set and oldset. This argument is
currently required to have a fixed architecture specific value
(equal to sizeof(kernel_sigset_t)).
The glibc sigprocmask() wrapper function hides these details from
us, transparently calling rt_sigprocmask() when the kernel
provides it.
Смотри также (See also)
kill(2), pause(2), sigaction(2), signal(2), sigpending(2),
sigsuspend(2), pthread_sigmask(3), sigqueue(3), sigsetops(3),
signal(7)
