devpath.c revision 344406 
1/*-
2 * Copyright (c) 2016 John Baldwin <jhb@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: stable/11/stand/efi/libefi/devpath.c 344406 2019-02-21 02:37:01Z kevans $");
29
30#include <efi.h>
31#include <efilib.h>
32
33static EFI_GUID ImageDevicePathGUID =
34    EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL_GUID;
35static EFI_GUID DevicePathGUID = DEVICE_PATH_PROTOCOL;
36static EFI_GUID DevicePathToTextGUID = EFI_DEVICE_PATH_TO_TEXT_PROTOCOL_GUID;
37static EFI_DEVICE_PATH_TO_TEXT_PROTOCOL *textProtocol;
38
39EFI_DEVICE_PATH *
40efi_lookup_image_devpath(EFI_HANDLE handle)
41{
42	EFI_DEVICE_PATH *devpath;
43	EFI_STATUS status;
44
45	status = BS->HandleProtocol(handle, &ImageDevicePathGUID,
46	    (VOID **)&devpath);
47	if (EFI_ERROR(status))
48		devpath = NULL;
49	return (devpath);
50}
51
52EFI_DEVICE_PATH *
53efi_lookup_devpath(EFI_HANDLE handle)
54{
55	EFI_DEVICE_PATH *devpath;
56	EFI_STATUS status;
57
58	status = BS->HandleProtocol(handle, &DevicePathGUID, (VOID **)&devpath);
59	if (EFI_ERROR(status))
60		devpath = NULL;
61	return (devpath);
62}
63
64CHAR16 *
65efi_devpath_name(EFI_DEVICE_PATH *devpath)
66{
67	static int once = 1;
68	EFI_STATUS status;
69
70	if (devpath == NULL)
71		return (NULL);
72	if (once) {
73		status = BS->LocateProtocol(&DevicePathToTextGUID, NULL,
74		    (VOID **)&textProtocol);
75		if (EFI_ERROR(status))
76			textProtocol = NULL;
77		once = 0;
78	}
79	if (textProtocol == NULL)
80		return (NULL);
81
82	return (textProtocol->ConvertDevicePathToText(devpath, TRUE, TRUE));
83}
84
85void
86efi_free_devpath_name(CHAR16 *text)
87{
88
89	BS->FreePool(text);
90}
91
92EFI_DEVICE_PATH *
93efi_devpath_last_node(EFI_DEVICE_PATH *devpath)
94{
95
96	if (IsDevicePathEnd(devpath))
97		return (NULL);
98	while (!IsDevicePathEnd(NextDevicePathNode(devpath)))
99		devpath = NextDevicePathNode(devpath);
100	return (devpath);
101}
102
103EFI_DEVICE_PATH *
104efi_devpath_trim(EFI_DEVICE_PATH *devpath)
105{
106	EFI_DEVICE_PATH *node, *copy;
107	size_t prefix, len;
108
109	if ((node = efi_devpath_last_node(devpath)) == NULL)
110		return (NULL);
111	prefix = (UINT8 *)node - (UINT8 *)devpath;
112	if (prefix == 0)
113		return (NULL);
114	len = prefix + DevicePathNodeLength(NextDevicePathNode(node));
115	copy = malloc(len);
116	if (copy != NULL) {
117		memcpy(copy, devpath, prefix);
118		node = (EFI_DEVICE_PATH *)((UINT8 *)copy + prefix);
119		SetDevicePathEndNode(node);
120	}
121	return (copy);
122}
123
124EFI_HANDLE
125efi_devpath_handle(EFI_DEVICE_PATH *devpath)
126{
127	EFI_STATUS status;
128	EFI_HANDLE h;
129
130	/*
131	 * There isn't a standard way to locate a handle for a given
132	 * device path.  However, querying the EFI_DEVICE_PATH protocol
133	 * for a given device path should give us a handle for the
134	 * closest node in the path to the end that is valid.
135	 */
136	status = BS->LocateDevicePath(&DevicePathGUID, &devpath, &h);
137	if (EFI_ERROR(status))
138		return (NULL);
139	return (h);
140}
141
142bool
143efi_devpath_match_node(EFI_DEVICE_PATH *devpath1, EFI_DEVICE_PATH *devpath2)
144{
145	size_t len;
146
147	if (devpath1 == NULL || devpath2 == NULL)
148		return (false);
149	if (DevicePathType(devpath1) != DevicePathType(devpath2) ||
150	    DevicePathSubType(devpath1) != DevicePathSubType(devpath2))
151		return (false);
152	len = DevicePathNodeLength(devpath1);
153	if (len != DevicePathNodeLength(devpath2))
154		return (false);
155	if (memcmp(devpath1, devpath2, len) != 0)
156		return (false);
157	return (true);
158}
159
160bool
161efi_devpath_match(EFI_DEVICE_PATH *devpath1, EFI_DEVICE_PATH *devpath2)
162{
163
164	if (devpath1 == NULL || devpath2 == NULL)
165		return (false);
166
167	while (true) {
168		if (!efi_devpath_match_node(devpath1, devpath2))
169			return false;
170		if (IsDevicePathEnd(devpath1))
171			break;
172		devpath1 = NextDevicePathNode(devpath1);
173		devpath2 = NextDevicePathNode(devpath2);
174	}
175	return (true);
176}
177
178bool
179efi_devpath_is_prefix(EFI_DEVICE_PATH *prefix, EFI_DEVICE_PATH *path)
180{
181	size_t len;
182
183	if (prefix == NULL || path == NULL)
184		return (false);
185
186	while (1) {
187		if (IsDevicePathEnd(prefix))
188			break;
189
190		if (DevicePathType(prefix) != DevicePathType(path) ||
191		    DevicePathSubType(prefix) != DevicePathSubType(path))
192			return (false);
193
194		len = DevicePathNodeLength(prefix);
195		if (len != DevicePathNodeLength(path))
196			return (false);
197
198		if (memcmp(prefix, path, len) != 0)
199			return (false);
200
201		prefix = NextDevicePathNode(prefix);
202		path = NextDevicePathNode(path);
203	}
204	return (true);
205}
206
207/*
208 * Skip over the 'prefix' part of path and return the part of the path
209 * that starts with the first node that's a MEDIA_DEVICE_PATH.
210 */
211EFI_DEVICE_PATH *
212efi_devpath_to_media_path(EFI_DEVICE_PATH *path)
213{
214
215	while (!IsDevicePathEnd(path)) {
216		if (DevicePathType(path) == MEDIA_DEVICE_PATH)
217			return (path);
218		path = NextDevicePathNode(path);
219	}
220	return (NULL);
221}
222
223UINTN
224efi_devpath_length(EFI_DEVICE_PATH  *path)
225{
226	EFI_DEVICE_PATH *start = path;
227
228	while (!IsDevicePathEnd(path))
229		path = NextDevicePathNode(path);
230	return ((UINTN)path - (UINTN)start) + DevicePathNodeLength(path);
231}
232