xref: /freebsd/lib/libkvm/kvm_getprocs.3 (revision d37ea99837e6ad50837fd9fe1771ddf1c3ba6002)
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36.\"     @(#)kvm_getprocs.3	8.1 (Berkeley) 6/4/93
37.\" $FreeBSD$
38.\"
39.Dd September 27, 2003
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 LIBRARY
48.Lb libkvm
49.Sh SYNOPSIS
50.In kvm.h
51.In sys/param.h
52.In sys/sysctl.h
53.In sys/user.h
54.\" .Fa kvm_t *kd
55.Ft struct kinfo_proc *
56.Fn kvm_getprocs "kvm_t *kd" "int op" "int arg" "int *cnt"
57.Ft char **
58.Fn kvm_getargv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
59.Ft char **
60.Fn kvm_getenvv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
61.Sh DESCRIPTION
62The
63.Fn kvm_getprocs
64function returns 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 Dv KERN_PROC_ALL
77all processes and kernel visible threads
78.It Dv KERN_PROC_PROC
79all processes, without threads
80.It Dv KERN_PROC_PID
81processes with process ID
82.Fa arg
83.It Dv KERN_PROC_PGRP
84processes with process group
85.Fa arg
86.It Dv KERN_PROC_SESSION
87processes with session
88.Fa arg
89.It Dv KERN_PROC_TTY
90processes with TTY
91.Fa arg
92.It Dv KERN_PROC_UID
93processes with effective user ID
94.Fa arg
95.It Dv KERN_PROC_RUID
96processes with real user ID
97.Fa arg
98.It Dv KERN_PROC_INC_THREAD
99modifier to return all kernel visible threads when filtering
100by process ID, process group, TTY, user ID, and real user ID
101.El
102.Pp
103The number of processes found is returned in the reference parameter
104.Fa cnt .
105The processes are returned as a contiguous array of kinfo_proc structures.
106This memory is locally allocated, and subsequent calls to
107.Fn kvm_getprocs
108and
109.Fn kvm_close
110will overwrite this storage.
111.Pp
112The
113.Fn kvm_getargv
114function returns a null-terminated argument vector that corresponds to the
115command line arguments passed to process indicated by
116.Fa p .
117Most likely, these arguments correspond to the values passed to
118.Xr exec 3
119on process creation.  This information is, however,
120deliberately under control of the process itself.
121Note that the original command name can be found, unaltered,
122in the p_comm field of the process structure returned by
123.Fn kvm_getprocs .
124.Pp
125The
126.Fa nchr
127argument indicates the maximum number of characters, including null bytes,
128to use in building the strings.  If this amount is exceeded, the string
129causing the overflow is truncated and the partial result is returned.
130This is handy for programs like
131.Xr ps 1
132and
133.Xr w 1
134that print only a one line summary of a command and should not copy
135out large amounts of text only to ignore it.
136If
137.Fa nchr
138is zero, no limit is imposed and all argument strings are returned in
139their entirety.
140.Pp
141The memory allocated to the argv pointers and string storage
142is owned by the kvm library.  Subsequent
143.Fn kvm_getprocs
144and
145.Xr kvm_close 3
146calls will clobber this storage.
147.Pp
148The
149.Fn kvm_getenvv
150function is similar to
151.Fn kvm_getargv
152but returns the vector of environment strings.  This data is
153also alterable by the process.
154.Sh RETURN VALUES
155The
156.Fn kvm_getprocs ,
157.Fn kvm_getargv ,
158and
159.Fn kvm_getenvv
160functions return
161.Dv NULL
162on failure.
163.Sh BUGS
164These routines do not belong in the kvm interface.
165.Sh SEE ALSO
166.Xr kvm 3 ,
167.Xr kvm_close 3 ,
168.Xr kvm_geterr 3 ,
169.Xr kvm_nlist 3 ,
170.Xr kvm_open 3 ,
171.Xr kvm_openfiles 3 ,
172.Xr kvm_read 3 ,
173.Xr kvm_write 3
174