kvm_getprocs, kvm_getargv, kvm_getenvv -- access user process state
Kernel Data Access Library (libkvm, -lkvm)
struct kinfo_proc *
kvm_getprocs(kvm_t *kd, int op, int arg, int *cnt);
kvm_getargv(kvm_t *kd, const struct kinfo_proc *p, int nchr);
kvm_getenvv(kvm_t *kd, const struct kinfo_proc *p, int nchr);
The kvm_getprocs() function 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_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
The number of processes found is returned in the reference parameter cnt.
The processes are returned as a contiguous array of kinfo_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 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 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
The kvm_getprocs(), kvm_getargv(), and kvm_getenvv() functions return
NULL on failure.
These routines do not belong in the kvm interface.
kvm(3), kvm_close(3), kvm_geterr(3), kvm_nlist(3), kvm_open(3),
kvm_openfiles(3), kvm_read(3), kvm_write(3)
FreeBSD 5.2.1 September 27, 2003 FreeBSD 5.2.1 [ Back ]