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SIGVEC(3) Linux Programmer's Manual SIGVEC(3)
sigvec, sigblock, sigsetmask, siggetmask, sigmask - BSD signal API
#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
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 This API is
obsolete: new applications should use the POSIX signal API (sigaction(2),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 handler
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).
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.
See the ERRORS under sigaction(2) and sigprocmask(2).
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.
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.
kill(2), pause(2), sigaction(2), signal(2), sigprocmask(2), raise(3),
sigpause(3), sigset(3), signal(7)
This page is part of release 3.32 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)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface