.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "BSD_SIGNAL" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" bsd_signal 
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.SH NAME
bsd_signal \- simplified signal facilities
.SH SYNOPSIS
.LP
\fB#include <signal.h>
.br
.sp
void (*bsd_signal(int\fP \fIsig\fP\fB, void (*\fP\fIfunc\fP\fB)(int)))(int);
\fP
\fB
.br
\fP
.SH DESCRIPTION
.LP
The \fIbsd_signal\fP() function provides a partially compatible interface
for programs written to historical system interfaces
(see APPLICATION USAGE).
.LP
The function call \fIbsd_signal\fP(\fIsig\fP, \fIfunc\fP) shall be
equivalent to the following:
.sp
.RS
.nf

\fBvoid (*bsd_signal(int sig, void (*func)(int)))(int)
{
    struct sigaction act, oact;
.sp

    act.sa_handler =\fP \fIfunc\fP\fB;
    act.sa_flags = SA_RESTART;

    sigemptyset(&act.sa_mask);
    sigaddset(&act.sa_mask,\fP \fIsig\fP\fB);
    if (sigaction(\fP\fIsig\fP\fB, &act, &oact) == -1)
        return(SIG_ERR);

    return(oact.sa_handler);
}
\fP
.fi
.RE
.LP
The handler function should be declared:
.sp
.RS
.nf

\fBvoid handler(int\fP \fIsig\fP\fB);
\fP
.fi
.RE
.LP
where \fIsig\fP is the signal number. The behavior is undefined if
\fIfunc\fP is a function that takes more than one argument,
or an argument of a different type.
.SH RETURN VALUE
.LP
Upon successful completion, \fIbsd_signal\fP() shall return the previous
action for \fIsig\fP. Otherwise, SIG_ERR shall be
returned and \fIerrno\fP shall be set to indicate the error.
.SH ERRORS
.LP
Refer to \fIsigaction\fP().
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
None.
.SH APPLICATION USAGE
.LP
This function is a direct replacement for the BSD \fIsignal\fP() 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 \fIsigaction\fP(). The \fIbsd_signal\fP() function differs
from \fIsignal\fP() in that the SA_RESTART flag is set and the SA_RESETHAND
is clear when
\fIbsd_signal\fP() is used. The state of these flags is not specified
for \fIsignal\fP().
.LP
It is recommended that new applications use the \fIsigaction\fP()
function.
.SH RATIONALE
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIsigaction\fP(), \fIsigaddset\fP(), \fIsigemptyset\fP(), \fIsignal\fP(),
the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, \fI<signal.h>\fP
.SH 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, 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 Standard, 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 .