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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 dif-
       fer (consult 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  argu-
       ment, 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 argument, the application has to be modified to use sigaction(). The bsd_signal()  function  dif-
       fers  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,  <sig-
       nal.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base  Specifica-
       tions  Issue  6,  Copyright (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 Stan-
       dard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                       BSD_SIGNAL(3P)