[dragonfly.git] / lib / libc / stdlib / atexit.3

.\" Copyright (c) 1990, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)atexit.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/stdlib/atexit.3,v 1.11 2007/01/09 00:28:09 imp Exp $
.\"
.Dd September 6, 2002
.Dt ATEXIT 3
.Os
.Sh NAME
.Nm atexit
.Nd register a function to be called on exit
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft int
.Fn atexit "void (*function)(void)"
.Sh DESCRIPTION
The
.Fn atexit
function
registers the given
.Fa function
to be called at program exit, whether via
.Xr exit 3
or via return from the program's
.Fn main .
Functions so registered are called in reverse order;
no arguments are passed.
.Pp
These functions must not call
.Fn exit ;
if it should be necessary to terminate the process while in such a
function, the
.Xr _exit 2
function should be used.
(Alternatively, the function may cause abnormal
process termination, for example by calling
.Xr abort 3 . )
.Pp
At least 32 functions can always be registered,
and more are allowed as long as sufficient memory can be allocated.
.\" XXX {ATEXIT_MAX} is not implemented yet
.Sh RETURN VALUES
.Rv -std atexit
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ENOMEM
No memory was available to add the function to the list.
The existing list of functions is unmodified.
.El
.Sh SEE ALSO
.Xr at_quick_exit 3 ,
.Xr exit 3
.Sh STANDARDS
The
.Fn atexit
function
conforms to
.St -isoC .
Commit	Line	Data
984263bc MD	1	.\" Copyright (c) 1990, 1991, 1993
	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" This code is derived from software contributed to Berkeley by
	5	.\" Chris Torek and the American National Standards Committee X3,
	6	.\" on Information Processing Systems.
	7	.\"
	8	.\" Redistribution and use in source and binary forms, with or without
	9	.\" modification, are permitted provided that the following conditions
	10	.\" are met:
	11	.\" 1. Redistributions of source code must retain the above copyright
	12	.\" notice, this list of conditions and the following disclaimer.
	13	.\" 2. Redistributions in binary form must reproduce the above copyright
	14	.\" notice, this list of conditions and the following disclaimer in the
	15	.\" documentation and/or other materials provided with the distribution.
984263bc MD	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" @(#)atexit.3 8.1 (Berkeley) 6/4/93
5d0641a4	33	.\" $FreeBSD: src/lib/libc/stdlib/atexit.3,v 1.11 2007/01/09 00:28:09 imp Exp $
984263bc	34	.\"
5d0641a4	35	.Dd September 6, 2002
984263bc MD	36	.Dt ATEXIT 3
	37	.Os
	38	.Sh NAME
	39	.Nm atexit
	40	.Nd register a function to be called on exit
	41	.Sh LIBRARY
	42	.Lb libc
	43	.Sh SYNOPSIS
	44	.In stdlib.h
	45	.Ft int
	46	.Fn atexit "void (*function)(void)"
	47	.Sh DESCRIPTION
	48	The
	49	.Fn atexit
	50	function
	51	registers the given
5d0641a4	52	.Fa function
984263bc MD	53	to be called at program exit, whether via
	54	.Xr exit 3
	55	or via return from the program's
5d0641a4	56	.Fn main .
984263bc MD	57	Functions so registered are called in reverse order;
984263bc MD	58	no arguments are passed.
5d0641a4 PA	59	.Pp
	60	These functions must not call
	61	.Fn exit ;
	62	if it should be necessary to terminate the process while in such a
	63	function, the
	64	.Xr _exit 2
	65	function should be used.
	66	(Alternatively, the function may cause abnormal
	67	process termination, for example by calling
	68	.Xr abort 3 . )
	69	.Pp
984263bc MD	70	At least 32 functions can always be registered,
984263bc MD	71	and more are allowed as long as sufficient memory can be allocated.
5d0641a4	72	.\" XXX {ATEXIT_MAX} is not implemented yet
984263bc MD	73	.Sh RETURN VALUES
	74	.Rv -std atexit
	75	.Sh ERRORS
	76	.Bl -tag -width Er
	77	.It Bq Er ENOMEM
	78	No memory was available to add the function to the list.
	79	The existing list of functions is unmodified.
	80	.El
	81	.Sh SEE ALSO
f3adbb3c	82	.Xr at_quick_exit 3 ,
984263bc MD	83	.Xr exit 3
	84	.Sh STANDARDS
	85	The
	86	.Fn atexit
	87	function
	88	conforms to
	89	.St -isoC .