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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 $
38 .\" $DragonFly: src/lib/libkvm/kvm_getprocs.3,v 1.4 2007/02/01 10:33:25 corecode Exp $
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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 sys/types.h
52 .In kvm.h
53 .Ft struct kinfo_proc *
54 .Fn kvm_getprocs "kvm_t *kd" "int op" "int arg" "int *cnt"
55 .Ft char **
56 .Fn kvm_getargv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
57 .Ft char **
58 .Fn kvm_getenvv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
59 .Sh DESCRIPTION
60 .Fn kvm_getprocs
61 returns a (sub-)set of active processes in the kernel indicated by
62 .Fa kd .
63 The
64 .Fa op
65 and
66 .Fa arg
67 arguments constitute a predicate which limits the set of processes
68 returned. The value of
69 .Fa op
70 describes the filtering predicate as follows:
71 .Pp
72 .Bl -tag -width 20n -offset indent -compact
73 .It Sy KERN_PROC_ALL
74 all processes
75 .It Sy KERN_PROC_PID
76 processes with process id
77 .Fa arg
78 .It Sy KERN_PROC_PGRP
79 processes with process group
80 .Fa arg
81 .It Sy KERN_PROC_SESSION
82 processes with session
83 .Fa arg
84 .It Sy KERN_PROC_TTY
85 processes with tty
86 .Fa arg
87 .It Sy KERN_PROC_UID
88 processes with effective user id
89 .Fa arg
90 .It Sy KERN_PROC_RUID
91 processes with real user id
92 .Fa arg
93 .El
94 .Pp
95 If the list of processes should contain all light weight processes,
96 add the flag
97 .Sy KERN_PROC_FLAG_LWP
98 to
99 .Fa op .
100 .Pp
101 The number of processes found is returned in the reference parameter
102 .Fa cnt .
103 The processes are returned as a contiguous array of kinfo_proc structures.
104 This memory is locally allocated, and subsequent calls to
105 .Fn kvm_getprocs
106 and
107 .Fn kvm_close
108 will overwrite this storage.
109 .Pp
110 .Fn kvm_getargv
111 returns a null-terminated argument vector that corresponds to the
112 command line arguments passed to process indicated by
113 .Fa p .
114 Most likely, these arguments correspond to the values passed to
115 .Xr exec 3
116 on process creation. This information is, however,
117 deliberately under control of the process itself.
118 Note that the original command name can be found, unaltered,
119 in the p_comm field of the process structure returned by
120 .Fn kvm_getprocs .
121 .Pp
122 The
123 .Fa nchr
124 argument indicates the maximum number of characters, including null bytes,
125 to use in building the strings. If this amount is exceeded, the string
126 causing the overflow is truncated and the partial result is returned.
127 This is handy for programs like
128 .Xr ps 1
129 and
130 .Xr w 1
131 that print only a one line summary of a command and should not copy
132 out large amounts of text only to ignore it.
133 If
134 .Fa nchr
135 is zero, no limit is imposed and all argument strings are returned in
136 their entirety.
137 .Pp
138 The memory allocated to the argv pointers and string storage
139 is owned by the kvm library. Subsequent
140 .Fn kvm_getprocs
141 and
142 .Xr kvm_close 3
143 calls will clobber this storage.
144 .Pp
145 The
146 .Fn kvm_getenvv
147 function is similar to
148 .Fn kvm_getargv
149 but returns the vector of environment strings. This data is
150 also alterable by the process.
151 .Sh RETURN VALUES
152 .Fn kvm_getprocs ,
153 .Fn kvm_getargv ,
154 and
155 .Fn kvm_getenvv ,
156 all return
157 .Dv NULL
158 on failure.
159 .Sh SEE ALSO
160 .Xr kvm 3 ,
161 .Xr kvm_close 3 ,
162 .Xr kvm_geterr 3 ,
163 .Xr kvm_nlist 3 ,
164 .Xr kvm_open 3 ,
165 .Xr kvm_openfiles 3 ,
166 .Xr kvm_read 3 ,
167 .Xr kvm_write 3
168 .Sh BUGS
169 These routines do not belong in the kvm interface.