.\"
.\" Copyright (c) 2015 Mark Johnston <markj@FreeBSD.org>
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd December 7, 2015
.Dt PROC_RWMEM 9
.Os
.Sh NAME
.Nm proc_rwmem ,
.Nm proc_readmem ,
.Nm proc_writemem
.Nd read from or write to a process address space
.Sh SYNOPSIS
.In sys/types.h
.In sys/ptrace.h
.Ft int
.Fn proc_rwmem "struct proc *p" "struct uio *uio"
.Ft ssize_t
.Fn proc_readmem "struct thread *td" "struct proc *p" "vm_offset_t va" "void *buf" "size_t len"
.Ft ssize_t
.Fn proc_writemem "struct thread *td" "struct proc *p" "vm_offset_t va" "void *buf" "size_t len"
.Sh DESCRIPTION
These functions are used to read to or write from the address space of the
process
.Fa p .
The
.Fn proc_rwmem
function requires the caller to specify the I/O parameters using a
.Vt "struct uio" ,
described in
.Xr uio 9 .
The
.Fn proc_readmem
and
.Fn proc_writemem
functions provide a simpler, less general interface which allows the caller to
read into or write the kernel buffer
.Fa buf
of size
.Fa len
from or to the memory at offset
.Fa va
in the address space of
.Fa p .
The operation is performed on behalf of thread
.Fa td ,
which will most often be the current thread.
.Pp
These functions may sleep and thus may not be called with any non-sleepable
locks held.
The process
.Fa p
must be held by the caller using
.Xr PHOLD 9 .
.Sh RETURN VALUES
The
.Fn proc_rwmem
function returns
.Dv 0
on success.
.Dv EFAULT
is returned if the specified user address is invalid, and
.Dv ENOMEM
is returned if the target pages could not be faulted in due to a resource
shortage.
.Pp
The
.Fn proc_readmem
and
.Fn proc_writemem
functions return the number of bytes read or written, respectively.
This may be smaller than the number of bytes requested, for example if the
request spans multiple pages in the process address space and one of them after
the first is not mapped.
Otherwise, -1 is returned.
.Sh SEE ALSO
.Xr copyin 9 ,
.Xr locking 9 ,
.Xr PHOLD 9 ,
.Xr uio 9
.Sh AUTHORS
This manual page was written by
.An Mark Johnston Aq Mt markj@FreeBSD.org .