from Steve McCanne

[unix-history] / usr / src / lib / libkvm / kvm_getprocs.3

.\" Copyright (c) 1992 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)kvm_getprocs.3      5.1 (Berkeley) %G%
.\"
.Dd 
.Dt KVM_GETPROCS 3
.Os
.Sh NAME
.Nm kvm_getprocs ,
.Nm kvm_getargv ,
.Nm kvm_getenvv 
.Nd access user process state
.Sh SYNOPSIS
.Fd #include <kvm.h>
.Fd #include <sys/kinfo.h>
.Fd #include <sys/kinfo_proc.h>
.\" .Fa kvm_t *kd
.br
.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_getargv "kvm_t *kd" "const struct kinfo_proc *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 KINFO_PROC_ALL
all processes
.It Sy KINFO_PROC_PID
processes with process id 
.Fa arg
.It Sy KINFO_PROC_PGRP
processes with process group
.Fa arg
.It Sy KINFO_PROC_SESSION
processes with session
.Fa arg
.It Sy KINFO_PROC_TTY
processes with tty
.Fa arg
.It Sy KINFO_PROC_UID
processes with effective user id
.Fa arg
.It Sy KINFO_PROC_RUID
processes with real user 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 kinfo_proc structures.
This memory is owned by kvm and is not guaranteed to be persistent across
subsequent kvm library calls.  Data should be copied out if it needs to be
saved.
.Pp
.Fn kvm_getargv
returns an 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.  However, this information exists only the
process address space, and is therefore alterable by 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
that print only a one line summary of a command and should copy
out large numbers arguments that will not be printed.
.Pp
The memory allocated to the argv pointers as well as the string storage
are owned by the kvm library.  Data must be copied out of this
structure before calling another kvm function.
.Pp
The
.Fn kvm_getenvv
function is similar to
.Fn kvm_getargv
but returns the vector of environment strings.  This is data is
also alterable by the process.
.Sh RETURN VALUES
.Fn kvm_getprocs ,
.Fn kvm_getargv ,
and
.Fn kvm_getenvv ,
all return NULL on failure.
.Pp
.Sh BUGS
These routines do not belong in the kvm interface.
.Sh SEE ALSO
.Xr kvm 3 ,
.Xr kvm_open 3 ,
.Xr kvm_openfiles 3 ,
.Xr kvm_close 3 ,
.Xr kvm_read 3 ,
.Xr kvm_write 3 ,
.Xr kvm_nlist 3 ,
.Xr kvm_geterr 3