kvm_getargv(3) - NetBSD Manual Pages

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KVM_GETPROCS(3)         NetBSD Library Functions Manual        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>

     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);

     struct kinfo_proc2 *
     kvm_getproc2(kvm_t *kd, int op, int arg, int elemsize, int *cnt);

     char **
     kvm_getargv2(kvm_t *kd, const struct kinfo_proc2 *p, int nchr);

     char **
     kvm_getenvv2(kvm_t *kd, const struct kinfo_proc2 *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 fil-
     tering predicate as follows:

           KERN_PROC_ALL         all processes
           KERN_PROC_PID         processes with process id arg
           KERN_PROC_PGRP        processes with process group arg
           KERN_PROC_SESSION     processes with session id arg
           KERN_PROC_TTY         processes with tty device arg
           KERN_PROC_UID         processes with effective user id arg
           KERN_PROC_RUID        processes with real user id arg
           KERN_PROC_GID         processes with effective group id arg
           KERN_PROC_RGID        processes with real group id arg

     The number of processes found is returned in the reference parameter cnt.
     The processes are returned as a contiguous array of kinfo_proc struc-
     tures.  This memory is locally allocated, and subsequent calls to
     kvm_getprocs() and kvm_close() will overwrite this storage.

     If the op argument for kvm_getprocs() is KERN_PROC_TTY, arg can also be
     KERN_PROC_TTY_NODEV to select processes with no controlling tty and
     KERN_PROC_TTY_REVOKE to select processes which have had their controlling
     tty revoked.

     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 con-
     trol 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 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.

     kvm_getproc2() is similar to kvm_getprocs() but returns an array of
     kinfo_proc2 structures.  Additionally, only the first elemsize bytes of
     each array entry are returned.  If the size of the kinfo_proc2 structure
     increases in size in a future release of NetBSD the kernel will only
     return the requested amount of data for each array entry and programs
     that use kvm_getproc2() will continue to function without the need for
     recompilation.

     The kvm_getargv2() and kvm_getenvv2() are equivalents to the
     kvm_getargv() and kvm_getenvv() functions but use a kinfo_proc2 structure
     to specify the process.

     If called against an active kernel, the kvm_getproc2(), kvm_getargv2(),
     and kvm_getenvv2() functions will use the sysctl(3) interface and do not
     require access to the kernel memory device file or swap device.


RETURN VALUES

     kvm_getprocs(), kvm_getargv(), kvm_getenvv(), kvm_getproc2(),
     kvm_getargv2(), and kvm_getenvv2() all 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.

NetBSD 5.2.3                   February 10, 2004                  NetBSD 5.2.3