KVM_GETPROCS(3)

NAME
kvm_getprocs, kvm_getargv, kvm_getenvv - access user process state

SYNOPSIS
#include <sys/param.h>
#include <sys/sysctl.h>
#include <kvm.h>
struct kinfo_proc *
kvm_getprocs(kvm_t *kd, int op, int arg, size_t elemsize, 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
kvm_getprocs() returns a (sub-)set of active processes in the kernel indicated by kd. The op and arg arguments constitute a predicate which limits the set of processes returned. The value of op describes the filtering predicate as follows:

KERN_PROC_KTHREAD
    all processes (user-level plus kernel threads)
KERN_PROC_ALL
    all user-level processes
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(4) arg
KERN_PROC_UID
    processes with effective user ID arg
KERN_PROC_RUID
    processes with real user ID arg

Only the first elemsize bytes of each array entry are returned. If the size of the kinfo_proc structure increases in size in a future release of OpenBSD, the library will only return the requested amount of data for each array entry and programs that use kvm_getprocs() will continue to function without the need for recompilation. The number of processes found is returned in the reference parameter cnt. The processes are returned as a contiguous array of kinfo_proc structures, the definition for which is available in <sys/sysctl.h>. This memory is locally allocated, and subsequent calls to kvm_getprocs() and kvm_close() will overwrite this storage.

kvm_getargv() returns a null-terminated argument 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 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 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 imposed and all argument strings are returned in their entirety.

The memory allocated to the argv pointers and string storage is owned by the kvm(3) 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
kvm_getprocs(), kvm_getargv(), and kvm_getenvv() all return NULL on failure.

SEE ALSO
kvm(3), kvm_geterr(3), kvm_nlist(3), kvm_open(3), kvm_read(3)

BUGS
These routines do not belong in the kvm(3) interface.