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\"     @(#)kvm_getprocs.3       8.1 (Berkeley) 6/4/93
\"
Dd January 9, 2018
Dt KVM_GETPROCS 3
Os
Sh NAME
Nm kvm_getprocs ,
Nm kvm_getargv ,
Nm kvm_getenvv ,
Nm kvm_getproc2 ,
Nm kvm_getargv2 ,
Nm kvm_getenvv2
Nd access user process state
Sh LIBRARY
Lb libkvm
Sh SYNOPSIS
In kvm.h
In sys/param.h
In sys/sysctl.h
\" .Fa kvm_t *kd
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"
Ft struct kinfo_proc2 *
Fn kvm_getproc2 "kvm_t *kd" "int op" "int arg" "size_t elemsize" "int *cnt"
Ft char **
Fn kvm_getargv2 "kvm_t *kd" "const struct kinfo_proc2 *p" "int nchr"
Ft char **
Fn kvm_getenvv2 "kvm_t *kd" "const struct kinfo_proc2 *p" "int nchr"
Sh DESCRIPTION
Fn kvm_getprocs
returns a (sub-)set of active processes in the kernel indicated by
Fa kd .
The
Fa op
and
Fa arg
arguments constitute a predicate
which limits the set of processes returned.
The value of
Fa op
describes the filtering predicate as follows:
Pp
Bl -tag -width 20n -offset indent -compact
It Sy KERN_PROC_ALL
all processes
It Sy KERN_PROC_PID
processes with process id
Fa arg
It Sy KERN_PROC_PGRP
processes with process group
Fa arg
It Sy KERN_PROC_SESSION
processes with session id
Fa arg
It Sy KERN_PROC_TTY
processes with tty device
Fa arg
It Sy KERN_PROC_UID
processes with effective user id
Fa arg
It Sy KERN_PROC_RUID
processes with real user id
Fa arg
It Sy KERN_PROC_GID
processes with effective group id
Fa arg
It Sy KERN_PROC_RGID
processes with real group id
Fa arg
El
Pp
The number of processes found is returned in the reference parameter
Fa cnt .
The processes are returned as a contiguous array of
Sy kinfo_proc
structures.
This memory is locally allocated, and subsequent calls to
Fn kvm_getprocs
and
Fn kvm_close
will overwrite this storage.
Pp
If the
Fa op
argument for
Fn kvm_getprocs
is
Sy KERN_PROC_TTY ,
Fa arg
can also be
Sy KERN_PROC_TTY_NODEV
to select processes with no controlling tty and
Sy KERN_PROC_TTY_REVOKE
to select processes which have had their controlling tty
revoked.
Pp
Fn kvm_getargv
returns a null-terminated argument vector that corresponds to the
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,
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
The
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
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
is zero, no limit is imposed and all argument strings are returned in
their entirety.
Pp
The memory allocated to the argv pointers and string storage
is owned by the kvm library.
Subsequent
Fn kvm_getprocs
and
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 also alterable by the process.
Pp
Fn kvm_getproc2
is similar to
Fn kvm_getprocs
but returns an array of
Sy kinfo_proc2
structures.
Additionally, only the first
Fa elemsize
bytes of each array entry are returned.
If the size of the
Sy kinfo_proc2
structure increases in size in a future release of
Nx
the kernel will only return the requested amount of data for
each array entry and programs that use
Fn kvm_getproc2
will continue to function without the need for recompilation.
Pp
The
Fn kvm_getargv2
and
Fn kvm_getenvv2
are equivalents to the
Fn kvm_getargv
and
Fn kvm_getenvv
functions but use a
Sy kinfo_proc2
structure to specify the process.
Pp
If called against an active kernel, the
Fn kvm_getproc2 ,
Fn kvm_getargv2 ,
and
Fn kvm_getenvv2
functions will use the
Xr sysctl 3
interface and do not require access to the kernel memory device
file or swap device.
Sh RETURN VALUES
Fn kvm_getprocs ,
Fn kvm_getargv ,
Fn kvm_getenvv ,
Fn kvm_getproc2 ,
Fn kvm_getargv2 ,
and
Fn kvm_getenvv2
all return
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
Sh BUGS
These routines do not belong in the kvm interface.

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