SIGVEC(3)		   Linux Programmers Manual		    SIGVEC(3)



NAME
       sigvec, sigblock, sigsetmask, siggetmask, sigmask - BSD signal API

SYNOPSIS
       #include 

       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  This  API  is
       obsolete:  new  applications  should  use  the POSIX signal API (sigac
       tion(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  han
       dler  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  call
	      ing 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 processs sig
       nal mask (like POSIX sigprocmask(SIG_BLOCK)), and returns the processs
       previous  signal  mask.	 Attempts  to  block  SIGKILL  or  SIGSTOP are
       silently ignored.

       The sigsetmask() function sets the processs signal mask to  the	value
       given  in  mask	(like POSIX sigprocmask(SIG_SETMASK)), and returns the
       processs previous signal mask.

       The siggetmask() function returns the processs  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 ori
       gin 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  func
       tion  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 3.05 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)