1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
24 */
25
26#pragma ident	"%Z%%M%	%I%	%E% SMI"
27
28/*
29 * Memory I/O backend.
30 *
31 * Simple backend that has main memory as its backing store.
32 */
33
34#include <mdb/mdb_io_impl.h>
35#include <mdb/mdb.h>
36
37typedef struct mem_data {
38	char *md_buf;
39	size_t md_size;
40	offset_t md_off;
41} mem_data_t;
42
43static ssize_t
44memio_read(mdb_io_t *io, void *buf, size_t nbytes)
45{
46	mem_data_t *mdp = io->io_data;
47
48	if (io->io_next == NULL) {
49		if (mdp->md_off + nbytes > mdp->md_size)
50			nbytes = (mdp->md_size - mdp->md_off);
51		bcopy(mdp->md_buf + mdp->md_off, buf, nbytes);
52		mdp->md_off += nbytes;
53		return (nbytes);
54	}
55
56	return (IOP_READ(io->io_next, buf, nbytes));
57}
58
59static off64_t
60memio_seek(mdb_io_t *io, off64_t offset, int whence)
61{
62	mem_data_t *mdp = io->io_data;
63
64	if (io->io_next == NULL) {
65		switch (whence) {
66		case SEEK_SET:
67			mdp->md_off = offset;
68			break;
69		case SEEK_CUR:
70			mdp->md_off += offset;
71			break;
72		case SEEK_END:
73			mdp->md_off = mdp->md_size + offset;
74			if (mdp->md_off > mdp->md_size)
75				mdp->md_off = mdp->md_size;
76			break;
77		default:
78			return (-1);
79		}
80
81		return (mdp->md_off);
82	}
83
84	return (IOP_SEEK(io->io_next, offset, whence));
85}
86
87static const mdb_io_ops_t memio_ops = {
88	memio_read,
89	no_io_write,
90	memio_seek,
91	no_io_ctl,
92	no_io_close,
93	no_io_name,
94	no_io_link,
95	no_io_unlink,
96	no_io_setattr,
97	no_io_suspend,
98	no_io_resume
99};
100
101mdb_io_t *
102mdb_memio_create(char *buf, size_t size)
103{
104	mdb_io_t *io = mdb_alloc(sizeof (mdb_io_t), UM_SLEEP);
105	mem_data_t *mdp = mdb_alloc(sizeof (mem_data_t), UM_SLEEP);
106
107	mdp->md_buf = buf;
108	mdp->md_size = size;
109	mdp->md_off = 0;
110
111	io->io_ops = &memio_ops;
112	io->io_data = mdp;
113	io->io_next = NULL;
114	io->io_refcnt = 0;
115
116	return (io);
117}
118