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       is obsolete: new applications should use the POSIX signal API (sigaction(2), sigprocmask(2), etc.).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)(int); /* 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; 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.  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 3.53 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								    2012-09-06								 SIGVEC(3)