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_getprocs()
sets the thread ID field accordingly for each thread except for the process
(main thread) which has it set to -1.
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
execve(2) 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.