1.\" $OpenBSD: mprotect.2,v 1.15 2010/02/12 21:49:10 jmc Exp $ 2.\" $NetBSD: mprotect.2,v 1.6 1995/10/12 15:41:08 jtc Exp $ 3.\" 4.\" Copyright (c) 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)mprotect.2 8.1 (Berkeley) 6/9/93 32.\" 33.Dd $Mdocdate: February 12 2010 $ 34.Dt MPROTECT 2 35.Os 36.Sh NAME 37.Nm mprotect 38.Nd control the protection of pages 39.Sh SYNOPSIS 40.Fd #include <sys/types.h> 41.Fd #include <sys/mman.h> 42.Ft int 43.Fn mprotect "void *addr" "size_t len" "int prot" 44.Sh DESCRIPTION 45The 46.Fn mprotect 47system call sets the access protections for the pages that contain 48the address range 49.Fa addr 50through 51.Fa addr 52\&+ 53.Fa len 54\- 1 55(inclusive). 56If 57.Fa len 58is 0, no action is taken on the page that contains 59.Fa addr . 60.Pp 61Not all implementations will guarantee protection on a page basis; 62the granularity of protection changes may be as large as an entire region. 63Nor will all implementations guarantee to give exactly the requested 64permissions; more permissions may be granted than requested by 65.Fa prot . 66.Pp 67The protections (region accessibility) are specified in the 68.Fa prot 69argument by 70.Tn OR Ns 'ing 71the following values: 72.Pp 73.Bl -tag -width "PROT_WRITEXX" -offset indent -compact 74.It Dv PROT_EXEC 75Pages may be executed. 76.It Dv PROT_READ 77Pages may be read. 78.It Dv PROT_WRITE 79Pages may be written. 80.It Dv PROT_NONE 81No permissions. 82.El 83.Sh RETURN VALUES 84Upon successful completion, 85a value of 0 is returned. 86Otherwise, a value of \-1 is returned and 87.Va errno 88is set to indicate the error. 89.Sh SEE ALSO 90.Xr madvise 2 , 91.Xr mincore 2 , 92.Xr msync 2 , 93.Xr munmap 2 94.Sh HISTORY 95The 96.Fn mprotect 97function first appeared in 98.Bx 4.4 . 99.Sh CAVEATS 100The 101.Ox 102implementation of 103.Fn mprotect 104does not require 105.Fa addr 106to be page-aligned, 107although other implementations may. 108