BSD_SIGNAL(3P)                                      POSIX Programmer's Manual                                     BSD_SIGNAL(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       bsd_signal - simplified signal facilities

SYNOPSIS
       #include <signal.h>

       void (*bsd_signal(int sig, void (*func)(int)))(int);


DESCRIPTION
       The  bsd_signal() function provides a partially compatible interface for programs written to historical system interfaces
       (see APPLICATION USAGE).

       The function call bsd_signal(sig, func) shall be equivalent to the following:


              void (*bsd_signal(int sig, void (*func)(int)))(int)
              {
                  struct sigaction act, oact;


                  act.sa_handler = func;
                  act.sa_flags = SA_RESTART;

                  sigemptyset(&act.sa_mask);
                  sigaddset(&act.sa_mask, sig);
                  if (sigaction(sig, &act, &oact) == -1)
                      return(SIG_ERR);

                  return(oact.sa_handler);
              }

       The handler function should be declared:


              void handler(int sig);

       where sig is the signal number. The behavior is undefined if func is a function that takes more than one argument, or  an
       argument of a different type.

RETURN VALUE
       Upon  successful  completion, bsd_signal() shall return the previous action for sig. Otherwise, SIG_ERR shall be returned
       and errno shall be set to indicate the error.

ERRORS
       Refer to sigaction().

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       This function is a direct replacement for the BSD signal() function for simple applications that are installing a single-
       argument  signal  handler  function. If a BSD signal handler function is being installed that expects more than one argu-
       ment, the application has to be modified to use sigaction(). The bsd_signal() function differs from signal() in that  the
       SA_RESTART flag is set and the SA_RESETHAND is clear when bsd_signal() is used. The state of these flags is not specified
       for signal().

       It is recommended that new applications use the sigaction() function.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       sigaction(), sigaddset(), sigemptyset(), signal(), the Base Definitions volume of IEEE Std 1003.1-2001, <signal.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy  between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard  is  the  referee   document.   The   original   Standard   can   be   obtained   online   at   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                BSD_SIGNAL(3P)