freebsd-dev/lib/libkvm/kvm_getprocs.3

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.\" Copyright (c) 1992, 1993
.\" The Regents of the University of California. All rights reserved.
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.\" This code is derived from software developed by the Computer Systems
.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract
.\" BG 91-66 and contributed to Berkeley.
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.\" may be used to endorse or promote products derived from this software
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.\" @(#)kvm_getprocs.3 8.1 (Berkeley) 6/4/93
1999-08-28 00:22:10 +00:00
.\" $FreeBSD$
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.\"
.Dd November 22, 2011
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.Dt KVM_GETPROCS 3
.Os
.Sh NAME
.Nm kvm_getprocs ,
.Nm kvm_getargv ,
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.Nm kvm_getenvv
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.Nd access user process state
.Sh LIBRARY
.Lb libkvm
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.Sh SYNOPSIS
.In kvm.h
.In sys/param.h
.In sys/sysctl.h
.In sys/user.h
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.Ft struct kinfo_proc *
.Fn kvm_getprocs "kvm_t *kd" "int op" "int arg" "int *cnt"
.Ft char **
.Fn kvm_getargv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
.Ft char **
.Fn kvm_getenvv "kvm_t *kd" "const struct kinfo_proc *p" "int nchr"
.Sh DESCRIPTION
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The
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.Fn kvm_getprocs
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function returns a (sub-)set of active processes in the kernel indicated by
.Fa kd .
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The
.Fa op
and
.Fa arg
arguments constitute a predicate which limits the set of processes
returned.
The value of
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.Fa op
describes the filtering predicate as follows:
.Pp
.Bl -tag -width 20n -offset indent -compact
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.It Dv KERN_PROC_ALL
all processes and kernel visible threads
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.It Dv KERN_PROC_PROC
all processes, without threads
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.It Dv KERN_PROC_PID
processes with process ID
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.Fa arg
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.It Dv KERN_PROC_PGRP
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processes with process group
.Fa arg
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.It Dv KERN_PROC_SESSION
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processes with session
.Fa arg
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.It Dv KERN_PROC_TTY
processes with TTY
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.Fa arg
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.It Dv KERN_PROC_UID
processes with effective user ID
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.Fa arg
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.It Dv KERN_PROC_RUID
processes with real user ID
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.Fa arg
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.It Dv KERN_PROC_INC_THREAD
modifier to return all kernel visible threads when filtering
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by process ID, process group, TTY, user ID, and real user ID
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.El
.Pp
The number of processes found is returned in the reference parameter
.Fa cnt .
The processes are returned as a contiguous array of kinfo_proc structures.
This memory is locally allocated, and subsequent calls to
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.Fn kvm_getprocs
and
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.Fn kvm_close
will overwrite this storage.
.Pp
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The
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.Fn kvm_getargv
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function returns a null-terminated argument vector that corresponds to the
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command line arguments passed to process indicated by
.Fa p .
Most likely, these arguments correspond to the values passed to
.Xr exec 3
on process creation.
This information is, however,
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deliberately under control of the process itself.
Note that the original command name can be found, unaltered,
in the p_comm field of the process structure returned by
.Fn kvm_getprocs .
.Pp
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The
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.Fa nchr
argument indicates the maximum number of characters, including null bytes,
to use in building the strings.
If this amount is exceeded, the string
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causing the overflow is truncated and the partial result is returned.
This is handy for programs like
.Xr ps 1
and
.Xr w 1
that print only a one line summary of a command and should not copy
out large amounts of text only to ignore it.
If
.Fa nchr
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is zero, no limit is imposed and all argument strings are returned in
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their entirety.
.Pp
The memory allocated to the argv pointers and string storage
is owned by the kvm library.
Subsequent
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.Fn kvm_getprocs
and
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.Xr kvm_close 3
calls will clobber this storage.
.Pp
The
.Fn kvm_getenvv
function is similar to
.Fn kvm_getargv
but returns the vector of environment strings.
This data is
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also alterable by the process.
.Sh RETURN VALUES
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The
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.Fn kvm_getprocs ,
.Fn kvm_getargv ,
and
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.Fn kvm_getenvv
functions return
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.Dv NULL
on failure.
.Sh SEE ALSO
.Xr kvm 3 ,
.Xr kvm_close 3 ,
.Xr kvm_geterr 3 ,
.Xr kvm_nlist 3 ,
.Xr kvm_open 3 ,
.Xr kvm_openfiles 3 ,
.Xr kvm_read 3 ,
.Xr kvm_write 3
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.Sh BUGS
These routines do not belong in the kvm interface.