Do not build bus modules for vkernels.
[dragonfly.git] / lib / libkvm / kvm_getprocs.3
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1.\" Copyright (c) 1992, 1993
2.\" The Regents of the University of California. All rights reserved.
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4.\" This code is derived from software developed by the Computer Systems
5.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract
6.\" BG 91-66 and contributed to Berkeley.
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36.\" @(#)kvm_getprocs.3 8.1 (Berkeley) 6/4/93
37.\" $FreeBSD: src/lib/libkvm/kvm_getprocs.3,v 1.6.2.7 2003/04/29 14:37:04 trhodes Exp $
0b84df5c 38.\" $DragonFly: src/lib/libkvm/kvm_getprocs.3,v 1.3 2006/02/17 19:35:07 swildner Exp $
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39.\"
40.Dd June 4, 1993
41.Dt KVM_GETPROCS 3
42.Os
43.Sh NAME
44.Nm kvm_getprocs ,
45.Nm kvm_getargv ,
46.Nm kvm_getenvv
47.Nd access user process state
48.Sh LIBRARY
49.Lb libkvm
50.Sh SYNOPSIS
51.In kvm.h
52.In sys/param.h
53.In sys/sysctl.h
54.In sys/user.h
55.\" .Fa kvm_t *kd
56.Ft struct kinfo_proc *
57.Fn kvm_getprocs "kvm_t *kd" "int op" "int arg" "int *cnt"
58.Ft char **
59.Fn kvm_getargv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
60.Ft char **
61.Fn kvm_getenvv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
62.Sh DESCRIPTION
63.Fn kvm_getprocs
64returns a (sub-)set of active processes in the kernel indicated by
65.Fa kd .
66The
67.Fa op
68and
69.Fa arg
70arguments constitute a predicate which limits the set of processes
71returned. The value of
72.Fa op
73describes the filtering predicate as follows:
74.Pp
75.Bl -tag -width 20n -offset indent -compact
76.It Sy KERN_PROC_ALL
77all processes
78.It Sy KERN_PROC_PID
79processes with process id
80.Fa arg
81.It Sy KERN_PROC_PGRP
82processes with process group
83.Fa arg
84.It Sy KERN_PROC_SESSION
85processes with session
86.Fa arg
87.It Sy KERN_PROC_TTY
88processes with tty
89.Fa arg
90.It Sy KERN_PROC_UID
91processes with effective user id
92.Fa arg
93.It Sy KERN_PROC_RUID
94processes with real user id
95.Fa arg
96.El
97.Pp
98The number of processes found is returned in the reference parameter
99.Fa cnt .
100The processes are returned as a contiguous array of kinfo_proc structures.
101This memory is locally allocated, and subsequent calls to
102.Fn kvm_getprocs
103and
104.Fn kvm_close
105will overwrite this storage.
106.Pp
107.Fn kvm_getargv
108returns a null-terminated argument vector that corresponds to the
109command line arguments passed to process indicated by
110.Fa p .
111Most likely, these arguments correspond to the values passed to
112.Xr exec 3
113on process creation. This information is, however,
114deliberately under control of the process itself.
115Note that the original command name can be found, unaltered,
116in the p_comm field of the process structure returned by
117.Fn kvm_getprocs .
118.Pp
119The
120.Fa nchr
121argument indicates the maximum number of characters, including null bytes,
122to use in building the strings. If this amount is exceeded, the string
123causing the overflow is truncated and the partial result is returned.
124This is handy for programs like
125.Xr ps 1
126and
127.Xr w 1
128that print only a one line summary of a command and should not copy
129out large amounts of text only to ignore it.
130If
131.Fa nchr
132is zero, no limit is imposed and all argument strings are returned in
133their entirety.
134.Pp
135The memory allocated to the argv pointers and string storage
136is owned by the kvm library. Subsequent
137.Fn kvm_getprocs
138and
139.Xr kvm_close 3
140calls will clobber this storage.
141.Pp
142The
143.Fn kvm_getenvv
144function is similar to
145.Fn kvm_getargv
146but returns the vector of environment strings. This data is
147also alterable by the process.
148.Sh RETURN VALUES
149.Fn kvm_getprocs ,
150.Fn kvm_getargv ,
151and
152.Fn kvm_getenvv ,
153all return
154.Dv NULL
155on failure.
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156.Sh SEE ALSO
157.Xr kvm 3 ,
158.Xr kvm_close 3 ,
159.Xr kvm_geterr 3 ,
160.Xr kvm_nlist 3 ,
161.Xr kvm_open 3 ,
162.Xr kvm_openfiles 3 ,
163.Xr kvm_read 3 ,
164.Xr kvm_write 3
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165.Sh BUGS
166These routines do not belong in the kvm interface.