kvm_getprocs

KVM_GETPROCS(3)           OpenBSD Programmer's Manual          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.

OpenBSD 5.1                     January 7, 2012                    OpenBSD 5.1