131 lines
3.4 KiB
Groff
131 lines
3.4 KiB
Groff
.\" $NetBSD: reallocarray.3,v 1.4 2015/07/26 02:29:44 kamil Exp $
|
|
.\"
|
|
.\" Copyright (c) 2015 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" 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.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
|
|
.\" COPYRIGHT HOLDERS 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.
|
|
.\"
|
|
.Dd February 5, 2015
|
|
.Dt REALLOCARRAY 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm reallocarray
|
|
.Nd reallocate memory for an array of elements checking for overflow
|
|
.Sh SYNOPSIS
|
|
.Vt #define _OPENBSD_SOURCE
|
|
.In stdlib.h
|
|
.Ft void *
|
|
.Fo reallocarray
|
|
.Fa "void *ptr"
|
|
.Fa "size_t nmemb"
|
|
.Fa "size_t size"
|
|
.Fc
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn reallocarray
|
|
function reallocates the pointer
|
|
.Fa ptr
|
|
to a size appropriate to handle an allocation of
|
|
.Fa nmemb
|
|
elements in an array where each of the array elements is
|
|
.Fa size
|
|
bytes using
|
|
.Xr realloc 3
|
|
and making sure that overflow does not happen in the multiplication of
|
|
.Dq "nmemb * size" .
|
|
.Pp
|
|
This function is provided for source compatibility with
|
|
.Ox
|
|
and
|
|
its use is discouraged in preference to
|
|
.Xr reallocarr 3 .
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn reallocarray
|
|
function will return
|
|
.Dv NULL
|
|
if there was overflow or if
|
|
.Xr realloc 3
|
|
failed setting
|
|
.Va errno
|
|
to
|
|
.Dv EOVERFLOW
|
|
or preserving the value from
|
|
.Xr realloc 3 .
|
|
.Sh SEE ALSO
|
|
.Xr malloc 3 ,
|
|
.Xr realloc 3 ,
|
|
.Xr reallocarr 3
|
|
.Sh STANDARDS
|
|
.Fn reallocarray
|
|
is an
|
|
.Ox
|
|
extension.
|
|
.Sh HISTORY
|
|
The
|
|
.Fn reallocarray
|
|
function first appeared in
|
|
.Ox 5.6 .
|
|
.Fn reallocarray
|
|
was redesigned in
|
|
.Nx 8
|
|
as
|
|
.Fn reallocarr 3 .
|
|
For compatibility reasons it's available since
|
|
.Nx 8
|
|
in the
|
|
.Vt _OPENBSD_SOURCE
|
|
namespace.
|
|
.Sh CAVEATS
|
|
The
|
|
.Fn reallocarray
|
|
function was designed to facilitate safe,
|
|
robust programming and overcome the shortcomings of the
|
|
.Xr malloc 3
|
|
and
|
|
.Xr realloc 3
|
|
functions by centralizing the overflow check in the multiplication of
|
|
.Fa nmemb
|
|
and
|
|
.Fa size .
|
|
.Pp
|
|
There are still portability issues (it does not solve
|
|
the
|
|
.Dv 0
|
|
sized allocation return ambiguity in the C standard: does
|
|
.Fn reallocarray
|
|
return
|
|
.Dv NULL
|
|
or a unique pointer to memory that cannot be accessed? Does a
|
|
.Dv NULL
|
|
mean that an error occurred, and can someone check
|
|
.Dv errno
|
|
in that case to find out what happened?).
|
|
.Pp
|
|
For this reason
|
|
.Nx
|
|
decided to go with an alternative implementation, and created
|
|
.Xr reallocarr 3 .
|