[unix-history] / lib / libc / i386 / sys / i386_get_ldt.2

.\" Copyright (c) 1980, 1991 Regents of the University of California.
.\" 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.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
.\"
.\"     from: @(#)fork.2	6.5 (Berkeley) 3/10/91
.\"	$Id: i386_get_ldt.2,v 1.2 1993/10/09 00:59:10 cgd Exp $
.\"
.Dd September 20, 1993
.Dt I386_GET_LDT 2
.Os FreeBSD
.Sh NAME
.Nm i386_get_ldt ,
.Nm i386_set_ldt
.Nd manage i386 per-process Local Descriptor Table entries
.Sh SYNOPSIS
.Fd #include <machine/segments.h>
.Fd #include <machine/sysarch.h>
.Ft int
.Fn i386_get_ldt "int start_sel" "union descriptor *descs" "int num_sels"
.Ft int
.Fn i386_set_ldt "int start_sel" "union descriptor *descs" "int num_sels"
.Sh DESCRIPTION
.Fn i386_get_ldt
will return the list of i386 descriptors that the process has in its
LDT.
.Fn i386_set_ldt
will set a list of i386 descriptors for the current process in its
LDT.
Both routines accept a starting selector number
.Fa start_sel
, an array of memory that
will contain the descriptors to be set or returned 
.Fa descs
, and the number of entries to set or return
.Fa num_sels .
.Pp
The argument
.Fa descs
can be either segment_descriptor or gate_descriptor and are defined in
.Fd <i386/segments.h> .
These structures are defined by the architecure
as disjoint bit-fields, so care must be taken in constructing them.
.Sh RETURN VALUES
Upon successful completion,
.Fn i386_get_ldt
returns the number of descriptors currently in the LDT.
.Fn i386_set_ldt
returns the first selector set.
Otherwise, a value of -1 is returned and the global
variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn i386_get_ldt
and
.Fn i386_set_ldt
will fail if:
.Bl -tag -width [EINVAL]
.It Bq Er EINVAL
An inappropriate parameter was used for
.Fa start_sel
or
.Fa num_sels .
.It Bq Er EACESS
The caller attempted to use a descriptor that would
circumvent protection or cause a failure.
.El
.Sh REFERENCES
i386 Microprocessor Programmer's Reference Manual, Intel
.Sh WARNING
You can really hose your process using this.
Commit	Line	Data
b37654fb DG	1	.\" Copyright (c) 1980, 1991 Regents of the University of California.
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" from: @(#)fork.2 6.5 (Berkeley) 3/10/91
	33	.\" $Id: i386_get_ldt.2,v 1.2 1993/10/09 00:59:10 cgd Exp $
	34	.\"
	35	.Dd September 20, 1993
	36	.Dt I386_GET_LDT 2
	37	.Os FreeBSD
	38	.Sh NAME
	39	.Nm i386_get_ldt ,
	40	.Nm i386_set_ldt
	41	.Nd manage i386 per-process Local Descriptor Table entries
	42	.Sh SYNOPSIS
	43	.Fd #include <machine/segments.h>
	44	.Fd #include <machine/sysarch.h>
	45	.Ft int
	46	.Fn i386_get_ldt "int start_sel" "union descriptor *descs" "int num_sels"
	47	.Ft int
	48	.Fn i386_set_ldt "int start_sel" "union descriptor *descs" "int num_sels"
	49	.Sh DESCRIPTION
	50	.Fn i386_get_ldt
	51	will return the list of i386 descriptors that the process has in its
	52	LDT.
	53	.Fn i386_set_ldt
	54	will set a list of i386 descriptors for the current process in its
	55	LDT.
	56	Both routines accept a starting selector number
	57	.Fa start_sel
	58	, an array of memory that
	59	will contain the descriptors to be set or returned
	60	.Fa descs
	61	, and the number of entries to set or return
	62	.Fa num_sels .
	63	.Pp
	64	The argument
65	.Fa descs
66	can be either segment_descriptor or gate_descriptor and are defined in
67	.Fd <i386/segments.h> .
68	These structures are defined by the architecure
69	as disjoint bit-fields, so care must be taken in constructing them.
70	.Sh RETURN VALUES
71	Upon successful completion,
72	.Fn i386_get_ldt
73	returns the number of descriptors currently in the LDT.
74	.Fn i386_set_ldt
75	returns the first selector set.
76	Otherwise, a value of -1 is returned and the global
77	variable
78	.Va errno
79	is set to indicate the error.
80	.Sh ERRORS
81	.Fn i386_get_ldt
82	and
83	.Fn i386_set_ldt
84	will fail if:
85	.Bl -tag -width [EINVAL]
86	.It Bq Er EINVAL
87	An inappropriate parameter was used for
88	.Fa start_sel
89	or
90	.Fa num_sels .
91	.It Bq Er EACESS
92	The caller attempted to use a descriptor that would
93	circumvent protection or cause a failure.
94	.El
95	.Sh REFERENCES
96	i386 Microprocessor Programmer's Reference Manual, Intel
97	.Sh WARNING
98	You can really hose your process using this.