xref: /dragonfly/lib/libkvm/kvm_getprocs.3 (revision 8edfbc5e) 
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32.\"     @(#)kvm_getprocs.3	8.1 (Berkeley) 6/4/93
33.\" $FreeBSD: src/lib/libkvm/kvm_getprocs.3,v 1.6.2.7 2003/04/29 14:37:04 trhodes Exp $
34.\"
35.Dd June 4, 1993
36.Dt KVM_GETPROCS 3
37.Os
38.Sh NAME
39.Nm kvm_getprocs ,
40.Nm kvm_getargv ,
41.Nm kvm_getenvv
42.Nd access user process state
43.Sh LIBRARY
44.Lb libkvm
45.Sh SYNOPSIS
46.In sys/types.h
47.In kvm.h
48.Ft struct kinfo_proc *
49.Fn kvm_getprocs "kvm_t *kd" "int op" "int arg" "int *cnt"
50.Ft char **
51.Fn kvm_getargv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
52.Ft char **
53.Fn kvm_getenvv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
54.Sh DESCRIPTION
55.Fn kvm_getprocs
56returns a (sub-)set of active processes in the kernel indicated by
57.Fa kd .
58The
59.Fa op
60and
61.Fa arg
62arguments constitute a predicate which limits the set of processes
63returned.
64The value of
65.Fa op
66describes the filtering predicate as follows:
67.Pp
68.Bl -tag -width ".Dv KERN_PROC_SESSION" -offset indent -compact
69.It Dv KERN_PROC_ALL
70all processes
71.It Dv KERN_PROC_PID
72processes with process id
73.Fa arg
74.It Dv KERN_PROC_PGRP
75processes with process group
76.Fa arg
77.It Dv KERN_PROC_SESSION
78processes with session
79.Fa arg
80.It Dv KERN_PROC_TTY
81processes with tty
82.Fa arg
83.It Dv KERN_PROC_UID
84processes with effective user id
85.Fa arg
86.It Dv KERN_PROC_RUID
87processes with real user id
88.Fa arg
89.El
90.Pp
91If the list of processes should contain all light weight processes,
92add the flag
93.Dv KERN_PROC_FLAG_LWP
94to
95.Fa op .
96.Pp
97The number of processes found is returned in the reference parameter
98.Fa cnt .
99The processes are returned as a contiguous array of kinfo_proc structures.
100This memory is locally allocated, and subsequent calls to
101.Fn kvm_getprocs
102and
103.Fn kvm_close
104will overwrite this storage.
105.Pp
106.Fn kvm_getargv
107returns a null-terminated argument vector that corresponds to the
108command line arguments passed to process indicated by
109.Fa p .
110Most likely, these arguments correspond to the values passed to
111.Xr exec 3
112on process creation.
113This information is, however, deliberately under control of the process itself.
114Note that the original command name can be found, unaltered,
115in the p_comm field of the process structure returned by
116.Fn kvm_getprocs .
117.Pp
118The
119.Fa nchr
120argument indicates the maximum number of characters, including null bytes,
121to use in building the strings.
122If 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.
137Subsequent
138.Fn kvm_getprocs
139and
140.Xr kvm_close 3
141calls will clobber this storage.
142.Pp
143The
144.Fn kvm_getenvv
145function is similar to
146.Fn kvm_getargv
147but returns the vector of environment strings.
148This data is also alterable by the process.
149.Sh RETURN VALUES
150.Fn kvm_getprocs ,
151.Fn kvm_getargv ,
152and
153.Fn kvm_getenvv ,
154all return
155.Dv NULL
156on failure.
157.Sh SEE ALSO
158.Xr kvm 3 ,
159.Xr kvm_close 3 ,
160.Xr kvm_geterr 3 ,
161.Xr kvm_nlist 3 ,
162.Xr kvm_open 3 ,
163.Xr kvm_openfiles 3 ,
164.Xr kvm_read 3 ,
165.Xr kvm_write 3
166.Sh BUGS
167These routines do not belong in the kvm interface.
168