1.\" $NetBSD: setreuid.2,v 1.23 2008/05/02 18:11:05 martin Exp $ 2.\" 3.\" Copyright (c) 1998, 2000, 2001 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Charles M. Hannum. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.\" 31.\" Copyright (c) 1980, 1991 The Regents of the University of California. 32.\" All rights reserved. 33.\" 34.\" Redistribution and use in source and binary forms, with or without 35.\" modification, are permitted provided that the following conditions 36.\" are met: 37.\" 1. Redistributions of source code must retain the above copyright 38.\" notice, this list of conditions and the following disclaimer. 39.\" 2. Redistributions in binary form must reproduce the above copyright 40.\" notice, this list of conditions and the following disclaimer in the 41.\" documentation and/or other materials provided with the distribution. 42.\" 3. Neither the name of the University nor the names of its contributors 43.\" may be used to endorse or promote products derived from this software 44.\" without specific prior written permission. 45.\" 46.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 47.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 48.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 49.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 50.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 51.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 52.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 53.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 54.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 55.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 56.\" SUCH DAMAGE. 57.\" 58.\" from: @(#)setreuid.2 6.4 (Berkeley) 3/10/91 59.\" 60.Dd January 5, 2001 61.Dt SETREUID 2 62.Os 63.Sh NAME 64.Nm setreuid 65.Nd set real and effective user ID's 66.Sh LIBRARY 67.Lb libc 68.Sh SYNOPSIS 69.In unistd.h 70.Ft int 71.Fn setreuid "uid_t ruid" "uid_t euid" 72.Sh DESCRIPTION 73.Bf -symbolic 74This interface is made obsolete by the saved ID functionality in 75.Xr setuid 2 76and 77.Xr seteuid 2 . 78.Ef 79.Pp 80The real and effective user ID's of the 81current process are set according to the arguments. 82If the real user ID is changed, the saved user ID is changed to the new 83value of the effective user ID. 84.Pp 85If 86.Fa ruid 87or 88.Fa euid 89is \-1, the current uid is filled in by the system. 90Unprivileged users may change the real user 91ID to the effective user ID, and may change the effective user ID to the 92real user ID or the saved user ID; only the super-user may 93make other changes. 94.Pp 95The 96.Fn setreuid 97function has been used to swap the real and effective user 98IDs in set-user-ID programs to temporarily relinquish the set-user-ID 99value. 100This purpose is now better served by the use of the 101.Fn seteuid 102function (see 103.Xr setuid 2 ) . 104.Pp 105When setting the real and effective user IDs to the same value, this 106function is equivalent to the 107.Fn setuid 108function. 109When setting only the effective user ID, this function is equivalent to 110the 111.Fn seteuid 112function. 113.Sh RETURN VALUES 114Upon successful completion, a value of 0 is returned. 115Otherwise, a value of \-1 is returned and 116.Va errno 117is set to indicate the error. 118.Sh ERRORS 119.Bl -tag -width Er 120.It Bq Er EPERM 121The current process is not the super-user and a change 122other than changing the effective user-id to the real user-id 123was specified. 124.El 125.Sh SEE ALSO 126.Xr getuid 2 , 127.Xr seteuid 2 , 128.Xr setgid 2 , 129.Xr setuid 2 130.Sh HISTORY 131The 132.Fn setreuid 133function call appeared in 134.Bx 4.2 . 135An incompatible version was implemented in 136.Bx 4.4 . 137It was reimplemented in 138.Nx 1.2 139in a way compatible with 140.Bx 4.3 , 141SunOS and Linux, but should not be used in new code. 142