NetBSD/lib/libkvm/kvm_getlwps.3

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.\" $NetBSD: kvm_getlwps.3,v 1.6 2009/03/10 23:49:07 joerg Exp $
.\"
.\"Copyright (c) 2002 The NetBSD Foundation, Inc.
.\"All rights reserved.
.\"
.\"This code is derived from software contributed to The NetBSD Foundation
.\"by Nathan J. Williams.
.\"
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.\"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.
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.\"THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\"``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\"PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\"CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.Dd February 10, 2004
.Dt KVM_GETLWPS 3
.Os
.Sh NAME
.Nm kvm_getlwps
.Nd access state of LWPs belonging to a user process
.Sh LIBRARY
.Lb libkvm
.Sh SYNOPSIS
.In kvm.h
.In sys/param.h
.In sys/sysctl.h
.\" .Fa kvm_t *kd
.Ft struct kinfo_lwp *
.Fn kvm_getlwps "kvm_t *kd" "int pid" "u_long procaddr" "int *elemsize" "int *cnt"
.Sh DESCRIPTION
.Fn kvm_getlwps
returns the set of LWPs belonging to the process specified by
.Fa pid
or
.Fa procaddr
in the kernel indicated by
.Fa kd .
The number of LWPs found is returned in the reference parameter
.Fa cnt .
The LWPs are returned as a contiguous array of
.Sy kinfo_lwp
structures.
This memory is locally allocated, and subsequent calls to
.Fn kvm_getlwps
and
.Fn kvm_close
will overwrite this storage.
.Pp
Only the first
.Fa elemsize
bytes of each array entry are returned.
If the size of the
.Sy kinfo_lwp
structure increases in size in a future release of
.Nx
the kernel will only return the requested amount of data for
each array entry and programs that use
.Fn kvm_getlwps
will continue to function without the need for recompilation.
.Pp
If called against an active kernel, the
.Fn kvm_getlwps
function will use the
.Xr sysctl 3
interface and return information about the process identified by
.Fa pid ;
otherwise the kernel memory device file or swap device will be
accessed and the process is identified by the location passed in
.Fa paddr .
.Sh RETURN VALUES
.Fn kvm_getlwps
returns
.Dv NULL
on failure.
.Sh SEE ALSO
.Xr kvm 3 ,
.Xr kvm_close 3 ,
.Xr kvm_geterr 3 ,
.Xr kvm_getproc2 3 ,
.Xr kvm_getprocs 3 ,
.Xr kvm_nlist 3 ,
.Xr kvm_open 3 ,
.Xr kvm_openfiles 3 ,
.Xr kvm_read 3 ,
.Xr kvm_write 3
.Sh BUGS
These routines do not belong in the kvm interface.