1.\" $NetBSD: malloc.3,v 1.6 1997/07/15 07:05:31 mikel Exp $ 2.\" 3.\" Copyright (c) 1980, 1991 Regents of the University of California. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the American National Standards Committee X3, on Information 8.\" Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" from: @(#)malloc.3 6.7 (Berkeley) 6/29/91 39.\" 40.Dd June 29, 1991 41.Dt MALLOC 3 42.Os BSD 4 43.Sh NAME 44.Nm malloc 45.Nd general memory allocation function 46.Sh SYNOPSIS 47.Fd #include <stdlib.h> 48.Ft void * 49.Fn malloc "size_t size" 50.Sh DESCRIPTION 51The 52.Fn malloc 53function allocates uninitialized space for an object whose 54size is specified by 55.Fa size . 56The 57.Fn malloc 58function maintains multiple lists of free blocks according to size, allocating 59space from the appropriate list. 60.Pp 61The allocated space is 62suitably aligned (after possible pointer 63coercion) for storage of any type of object. If the space is of 64.Em pagesize 65or larger, the memory returned will be page-aligned. 66.Sh RETURN VALUES 67The 68.Fn malloc 69function returns 70a pointer to the allocated space if successful; otherwise 71a null pointer is returned. 72.Sh SEE ALSO 73.Xr brk 2 , 74.Xr alloca 3 , 75.Xr calloc 3 , 76.Xr free 3 , 77.Xr getpagesize 3 , 78.Xr memory 3 , 79.Xr realloc 3 80.Sh STANDARDS 81The 82.Fn malloc 83function conforms to 84.St -ansiC . 85.Sh BUGS 86The current implementation of 87.Fn malloc 88does not always fail gracefully when system 89memory limits are approached. 90It may fail to allocate memory when larger free blocks could be broken 91up, or when limits are exceeded because the size is rounded up. 92It is optimized for sizes that are powers of two. 93