sigblock(3UCB) SunOS/BSD Compatibility Library Functions sigblock(3UCB)NAME
sigblock, sigmask, sigpause, sigsetmask - block signals
SYNOPSIS
/usr/ucb/cc [ flag ... ] file ...
#include <signal.h>
int sigblock(mask)
int mask;
int sigmask(signum)
int signum;
int sigpause(mask)
int mask;
int sigsetmask(mask)
int mask;
DESCRIPTION
sigblock() adds the signals specified in mask to the set of signals currently being blocked from delivery. Signals are blocked if the
appropriate bit in mask is a 1; the macro sigmask is provided to construct the mask for a given signum. sigblock() returns the previous
mask. The previous mask may be restored using sigsetmask().
sigpause() assigns mask to the set of masked signals and then waits for a signal to arrive; on return the set of masked signals is
restored. mask is usually 0 to indicate that no signals are now to be blocked. sigpause() always terminates by being interrupted, returning
-1 and setting errno to EINTR.
sigsetmask() sets the current signal mask (those signals that are blocked from delivery). Signals are blocked if the corresponding bit in
mask is a 1; the macro sigmask is provided to construct the mask for a given signum.
In normal usage, a signal is blocked using sigblock(). To begin a critical section, variables modified on the occurrence of the signal are
examined to determine that there is no work to be done, and the process pauses awaiting work by using sigpause() with the mask returned by
sigblock().
It is not possible to block SIGKILL, SIGSTOP, or SIGCONT, this restriction is silently imposed by the system.
RETURN VALUES
sigblock() and sigsetmask() return the previous set of masked signals. sigpause() returns -1 and sets errno to EINTR.
SEE ALSO cc(1B), kill(2), sigaction(2), signal(3UCB), sigvec(3UCB)NOTES
Use of these interfaces should be restricted to only applications written on BSD platforms. Use of these interfaces with any of the system
libraries or in multi-thread applications is unsupported.
SunOS 5.11 30 Oct 2007 sigblock(3UCB)
Check Out this Related Man Page
SIGVEC(3) Linux Programmer's Manual SIGVEC(3)NAME
sigvec, sigblock, sigsetmask, siggetmask, sigmask - BSD signal API
SYNOPSIS
#include <signal.h>
int sigvec(int sig, struct sigvec *vec, struct sigvec *ovec);
int sigmask(int signum);
int sigblock(int mask);
int sigsetmask(int mask);
int siggetmask(void);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
All functions shown above: _BSD_SOURCE
DESCRIPTION
These functions are provided in glibc as a compatibility interface for programs that make use of the historical BSD signal API. This API
is obsolete: new applications should use the POSIX signal API (sigaction(2), sigprocmask(2), etc.)
The sigvec() function sets and/or gets the disposition of the signal sig (like the POSIX sigaction(2)). If vec is not NULL, it points to a
sigvec structure that defines the new disposition for sig. If ovec is not NULL, it points to a sigvec structure that is used to return the
previous disposition of sig. To obtain the current disposition of sig without changing it, specify NULL for vec, and a non-NULL pointer
for ovec.
The dispositions for SIGKILL and SIGSTOP cannot be changed.
The sigvec structure has the following form:
struct sigvec {
void (*sv_handler)(); /* Signal disposition */
int sv_mask; /* Signals to be blocked in handler */
int sv_flags; /* Flags */
};
The sv_handler field specifies the disposition of the signal, and is either: the address of a signal handler function; or SIG_DFL meaning
the default disposition applies for the signal; or SIG_IGN meaning that the signal is ignored.
If sv_handler specifies the address of a signal handler, then sv_mask specifies a mask of signals that are to be blocked while the handler
is executing. In addition, the signal for which the handler is invoked is also blocked by default. Attempts to block SIGKILL or SIGSTOP
are silently ignored.
If sv_handler specifies the address of a signal handler, then the sv_flags field specifies flags controlling what happens when the handler
is called. This field may contain zero or more of the following flags:
SV_INTERRUPT
If the signal handler interrupts a blocking system call, then upon return from the handler the system call will not be restarted:
instead it will fail with the error EINTR. If this flag is not specified, then system calls are restarted by default.
SV_RESETHAND
Reset the disposition of the signal to the default before calling the signal handler. If this flag is not specified, then the han-
dler remains established until explicitly removed by a later call to sigvec() or until the process performs an execve(2).
SV_ONSTACK
Handle the signal on the alternate signal stack (historically established under BSD using the obsolete sigstack() function; the
POSIX replacement is sigaltstack(2)).
The sigmask() function constructs and returns a "signal mask" for signum. For example, we can initialize the vec.sv_mask field given to
sigvec() using code such as the following:
vec.sv_mask = sigmask(SIGQUIT) | sigpause(SIGABRT);
/* Block SIGQUIT and SIGABRT during
handler execution */
The sigblock() function adds the signals in mask to the process's signal mask (like POSIX sigprocmask(SIG_BLOCK)), and returns the
process's previous signal mask. Attempts to block SIGKILL or SIGSTOP are silently ignored.
The sigsetmask() function sets the process's signal mask to the value given in mask (like POSIX sigprocmask(SIG_SETMASK)), and returns the
process's previous signal mask.
The siggetmask() function returns the process's current signal mask. This call is equivalent to sigblock(0).
RETURN VALUE
The sigvec() function returns 0 on success; on error, it returns -1 and sets errno to indicate the error.
The sigblock() and sigsetmask() functions return the previous signal mask.
The sigmask() function returns the signal mask for signum.
ERRORS
See the ERRORS under sigaction(2) and sigprocmask(2).
CONFORMING TO
All of these functions were in 4.3BSD, except siggetmask(), whose origin is unclear. These functions are obsolete: do not use them in new
programs.
NOTES
On 4.3BSD, the signal() function provided reliable semantics (as when calling sigvec() with vec.sv_mask equal to 0). On System V, signal()
provides unreliable semantics. POSIX.1-2001 leaves these aspects of signal() unspecified. See signal(2) for further details.
In order to wait for a signal, BSD and System V both provided a function named sigpause(3), but this function has a different argument on
the two systems. See sigpause(3) for details.
SEE ALSO kill(2), pause(2), sigaction(2), signal(2), sigprocmask(2), raise(3), sigpause(3), sigset(3), signal(7)COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2007-07-26 SIGVEC(3)