kvm_getprocs(3)

NAME

kvm_getprocs, kvm_getargv, kvm_getenvv - access user process

state

LIBRARY

Kernel Data Access Library (libkvm, -lkvm)

SYNOPSIS

#include <kvm.h>
#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/user.h>
struct kinfo_proc *
kvm_getprocs(kvm_t *kd, int op, int arg, int *cnt);
char **
kvm_getargv(kvm_t  *kd,  const  struct  kinfo_proc  *p,  int
nchr);
char **
kvm_getenvv(kvm_t  *kd,  const  struct  kinfo_proc  *p,  int
nchr);

DESCRIPTION

The kvm_getprocs() function returns a (sub-)set of active

processes in
the kernel indicated by kd. The op and arg arguments con

stitute a predicate which limits the set of processes returned. The value

of op
describes the filtering predicate as follows:

KERN_PROC_ALL all processes and kernel visible

threads
KERN_PROC_PROC all processes, without threads
KERN_PROC_PID processes with process ID arg
KERN_PROC_PGRP processes with process group arg
KERN_PROC_SESSION processes with session arg
KERN_PROC_TTY processes with TTY arg
KERN_PROC_UID processes with effective user ID

arg
KERN_PROC_RUID processes with real user ID arg
KERN_PROC_INC_THREAD modifier to return all kernel

visible threads

when filtering by process ID,

process group,
TTY, user ID, and real user ID

The number of processes found is returned in the reference

parameter cnt.
The processes are returned as a contiguous array of kin

fo_proc structures. This memory is locally allocated, and subsequent

calls to
kvm_getprocs() and kvm_close() will overwrite this storage.

The kvm_getargv() function returns a null-terminated argu

ment vector that
corresponds to the command line arguments passed to process

indicated by
p. Most likely, these arguments correspond to the values

passed to
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 kvm_getprocs().

The nchr argument indicates the maximum number of charac

ters, 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 ps(1) and 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 nchr is zero, no limit is im

posed and all
argument strings are returned in their entirety.

The memory allocated to the argv pointers and string storage

is owned by
the kvm library. Subsequent kvm_getprocs() and kvm_close(3)

calls will
clobber this storage.

The kvm_getenvv() function is similar to kvm_getargv() but

returns the
vector of environment strings. This data is also alterable

by the process.

RETURN VALUES

The kvm_getprocs(), kvm_getargv(), and kvm_getenvv() func

tions return
NULL on failure.

SEE ALSO

kvm(3), kvm_close(3), kvm_geterr(3), kvm_nlist(3),

kvm_open(3),
kvm_openfiles(3), kvm_read(3), kvm_write(3)

BUGS

These routines do not belong in the kvm interface.

In order for kvm_getenvv(3) to function correctly, procfs(5)

must be
mounted on /proc.

BSD September 27, 2003

BSD