KVM_GETU(3KVM) Kernel VM Library Functions KVM_GETU(3KVM)

NAME

kvm_getu, kvm_getcmd - get the u-area or invocation arguments for a
process

SYNOPSIS

cc [ flag... ] file... -lkvm [ library...]
#include <kvm.h>
#include <sys/param.h>
#include <sys/user.h>
#include <sys/proc.h>

struct user *kvm_getu(kvm_t *kd, struct proc *proc);


int kvm_getcmd(kvm_t *kd, struct proc *proc, struct user *u, char ***arg,
char ***env);

DESCRIPTION

The kvm_getu() function reads the u-area of the process specified by
proc to an area of static storage associated with kd and returns a
pointer to it. Subsequent calls to kvm_getu() will overwrite this
static area.


The kd argument is a pointer to a kernel descriptor returned by
kvm_open(3KVM). The proc argument is a pointer to a copy in the
current process's address space of a proc structure, obtained, for
instance, by a prior kvm_nextproc(3KVM) call.


The kvm_getcmd() function constructs a list of string pointers that
represent the command arguments and environment that were used to
initiate the process specified by proc.


The kd argument is a pointer to a kernel descriptor returned by
kvm_open(3KVM). The u argument is a pointer to a copy in the current
process's address space of a user structure, obtained, for instance,
by a prior kvm_getu() call. If arg is not NULL, the command line
arguments are formed into a null-terminated array of string pointers.
The address of the first such pointer is returned in arg. If env is
not NULL, the environment is formed into a null-terminated array of
string pointers. The address of the first of these is returned in
env.


The pointers returned in arg and env refer to data allocated by
malloc() and should be freed by a call to free() when no longer
needed. See malloc(3C). Both the string pointers and the strings
themselves are deallocated when freed.


Since the environment and command line arguments might have been
modified by the user process, there is no guarantee that it will be
possible to reconstruct the original command at all. The
kvm_getcmd() function will make the best attempt possible, returning
-1 if the user process data is unrecognizable.

RETURN VALUES

On success, kvm_getu() returns a pointer to a copy of the u-area of
the process specified by proc. On failure, it returns NULL.


The kvm_getcmd() function returns 0 on success and -1 on failure. If
-1 is returned, the caller still has the option of using the command
line fragment that is stored in the u-area.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Stable |
+--------------------+-----------------+
|MT-Level | Unsafe |
+--------------------+-----------------+

SEE ALSO

malloc(3C), kvm_kread(3KVM), kvm_nextproc(3KVM), kvm_open(3KVM),
libkvm(3LIB), attributes(7)

NOTES

On systems that support both 32-bit and 64-bit processes, the 64-bit
implementation of libkvm ensures that the arg and env pointer arrays
for kvm_getcmd() are translated to the same form as if they were
64-bit processes. Applications that wish to access the raw 32-bit
stack directly can use kvm_uread(). See kvm_read(3KVM).

May 2, 2002 KVM_GETU(3KVM)