freebsd-dev/lib/libc/stdlib/atexit.3
David Chisnall 0a31efe016 Implement quick_exit() / at_quick_exit() from C++11 / C1x. Also add a
__noreturn macro and modify the other exiting functions to use it.

The __noreturn macro, unlike __dead2, must be used BEFORE the function.
This is in line with the C and C++ specifications that place _Noreturn (c1x)
and [[noreturn]] (C++11) in front of the functions.  As with __dead2, this
macro falls back to using the GCC attribute.

Unfortunately, clang currently sets the same value for the C version macro
in C99 and C1x modes, so these functions are hidden by default.  At some
point before 10.0, I need to go through the headers and clean up the C1x /
C++11 visibility.

Reviewed by:	brooks (mentor)
2011-12-07 15:25:48 +00:00

90 lines
3.0 KiB
Groff

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.\" @(#)atexit.3 8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.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 .