xref: /freebsd/lib/libkvm/kvm_getprocs.3 (revision 380a989b3223d455375b4fae70fd0b9bdd43bafb)
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36.\"     @(#)kvm_getprocs.3	8.1 (Berkeley) 6/4/93
37.\"	$Id$
38.\"
39.Dd June 4, 1993
40.Dt KVM_GETPROCS 3
41.Os
42.Sh NAME
43.Nm kvm_getprocs ,
44.Nm kvm_getargv ,
45.Nm kvm_getenvv
46.Nd access user process state
47.Sh SYNOPSIS
48.Fd #include <kvm.h>
49.Fd #include <sys/param.h>
50.Fd #include <sys/sysctl.h>
51.\" .Fa kvm_t *kd
52.br
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
61returns a (sub-)set of active processes in the kernel indicated by
62.Fa kd.
63The
64.Fa op
65and
66.Fa arg
67arguments constitute a predicate which limits the set of processes
68returned.  The value of
69.Fa op
70describes the filtering predicate as follows:
71.Pp
72.Bl -tag -width 20n -offset indent -compact
73.It Sy KERN_PROC_ALL
74all processes
75.It Sy KERN_PROC_PID
76processes with process id
77.Fa arg
78.It Sy KERN_PROC_PGRP
79processes with process group
80.Fa arg
81.It Sy KERN_PROC_SESSION
82processes with session
83.Fa arg
84.It Sy KERN_PROC_TTY
85processes with tty
86.Fa arg
87.It Sy KERN_PROC_UID
88processes with effective user id
89.Fa arg
90.It Sy KERN_PROC_RUID
91processes with real user id
92.Fa arg
93.El
94.Pp
95The number of processes found is returned in the reference parameter
96.Fa cnt .
97The processes are returned as a contiguous array of kinfo_proc structures.
98This memory is locally allocated, and subsequent calls to
99.Fn kvm_getprocs
100and
101.Fn kvm_close
102will overwrite this storage.
103.Pp
104.Fn kvm_getargv
105returns a null-terminated argument vector that corresponds to the
106command line arguments passed to process indicated by
107.Fa p .
108Most likely, these arguments correspond to the values passed to
109.Xr exec 3
110on process creation.  This information is, however,
111deliberately under control of the process itself.
112Note that the original command name can be found, unaltered,
113in the p_comm field of the process structure returned by
114.Fn kvm_getprocs .
115.Pp
116The
117.Fa nchr
118argument indicates the maximum number of characters, including null bytes,
119to use in building the strings.  If this amount is exceeded, the string
120causing the overflow is truncated and the partial result is returned.
121This is handy for programs like
122.Xr ps 1
123and
124.Xr w 1
125that print only a one line summary of a command and should not copy
126out large amounts of text only to ignore it.
127If
128.Fa nchr
129is zero, no limit is imposed and all argument strings are returned in
130their entirety.
131.Pp
132The memory allocated to the argv pointers and string storage
133is owned by the kvm library.  Subsequent
134.Fn kvm_getprocs
135and
136.Xr kvm_close 3
137calls will clobber this storage.
138.Pp
139The
140.Fn kvm_getenvv
141function is similar to
142.Fn kvm_getargv
143but returns the vector of environment strings.  This data is
144also alterable by the process.
145.Sh RETURN VALUES
146.Fn kvm_getprocs ,
147.Fn kvm_getargv ,
148and
149.Fn kvm_getenvv ,
150all return
151.Dv NULL
152on failure.
153.Pp
154.Sh BUGS
155These routines do not belong in the kvm interface.
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
165