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David Howellsda4458b2009-02-12 10:40:10 +00001/* RomFS storage access routines
2 *
3 * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/fs.h>
13#include <linux/mtd/super.h>
14#include <linux/buffer_head.h>
15#include "internal.h"
16
17#if !defined(CONFIG_ROMFS_ON_MTD) && !defined(CONFIG_ROMFS_ON_BLOCK)
18#error no ROMFS backing store interface configured
19#endif
20
21#ifdef CONFIG_ROMFS_ON_MTD
Artem Bityutskiyc382fb42012-01-30 15:11:44 +020022#define ROMFS_MTD_READ(sb, ...) mtd_read((sb)->s_mtd, ##__VA_ARGS__)
David Howellsda4458b2009-02-12 10:40:10 +000023
24/*
25 * read data from an romfs image on an MTD device
26 */
27static int romfs_mtd_read(struct super_block *sb, unsigned long pos,
28 void *buf, size_t buflen)
29{
30 size_t rlen;
31 int ret;
32
33 ret = ROMFS_MTD_READ(sb, pos, buflen, &rlen, buf);
34 return (ret < 0 || rlen != buflen) ? -EIO : 0;
35}
36
37/*
38 * determine the length of a string in a romfs image on an MTD device
39 */
40static ssize_t romfs_mtd_strnlen(struct super_block *sb,
41 unsigned long pos, size_t maxlen)
42{
43 ssize_t n = 0;
44 size_t segment;
45 u_char buf[16], *p;
46 size_t len;
47 int ret;
48
49 /* scan the string up to 16 bytes at a time */
50 while (maxlen > 0) {
51 segment = min_t(size_t, maxlen, 16);
52 ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
53 if (ret < 0)
54 return ret;
55 p = memchr(buf, 0, len);
56 if (p)
57 return n + (p - buf);
58 maxlen -= len;
59 pos += len;
60 n += len;
61 }
62
63 return n;
64}
65
66/*
67 * compare a string to one in a romfs image on MTD
68 * - return 1 if matched, 0 if differ, -ve if error
69 */
David Howells84baf742009-04-23 16:41:13 +010070static int romfs_mtd_strcmp(struct super_block *sb, unsigned long pos,
71 const char *str, size_t size)
David Howellsda4458b2009-02-12 10:40:10 +000072{
David Howells84baf742009-04-23 16:41:13 +010073 u_char buf[17];
David Howellsda4458b2009-02-12 10:40:10 +000074 size_t len, segment;
75 int ret;
76
David Howells84baf742009-04-23 16:41:13 +010077 /* scan the string up to 16 bytes at a time, and attempt to grab the
78 * trailing NUL whilst we're at it */
79 buf[0] = 0xff;
80
David Howellsda4458b2009-02-12 10:40:10 +000081 while (size > 0) {
David Howells84baf742009-04-23 16:41:13 +010082 segment = min_t(size_t, size + 1, 17);
David Howellsda4458b2009-02-12 10:40:10 +000083 ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
84 if (ret < 0)
85 return ret;
David Howells84baf742009-04-23 16:41:13 +010086 len--;
David Howellsda4458b2009-02-12 10:40:10 +000087 if (memcmp(buf, str, len) != 0)
88 return 0;
David Howells84baf742009-04-23 16:41:13 +010089 buf[0] = buf[len];
David Howellsda4458b2009-02-12 10:40:10 +000090 size -= len;
91 pos += len;
92 str += len;
93 }
94
David Howells84baf742009-04-23 16:41:13 +010095 /* check the trailing NUL was */
96 if (buf[0])
97 return 0;
98
David Howellsda4458b2009-02-12 10:40:10 +000099 return 1;
100}
101#endif /* CONFIG_ROMFS_ON_MTD */
102
103#ifdef CONFIG_ROMFS_ON_BLOCK
104/*
105 * read data from an romfs image on a block device
106 */
107static int romfs_blk_read(struct super_block *sb, unsigned long pos,
108 void *buf, size_t buflen)
109{
110 struct buffer_head *bh;
111 unsigned long offset;
112 size_t segment;
113
114 /* copy the string up to blocksize bytes at a time */
115 while (buflen > 0) {
116 offset = pos & (ROMBSIZE - 1);
117 segment = min_t(size_t, buflen, ROMBSIZE - offset);
118 bh = sb_bread(sb, pos >> ROMBSBITS);
119 if (!bh)
120 return -EIO;
121 memcpy(buf, bh->b_data + offset, segment);
122 brelse(bh);
David Howells4b2b0b92009-04-23 16:41:18 +0100123 buf += segment;
David Howellsda4458b2009-02-12 10:40:10 +0000124 buflen -= segment;
125 pos += segment;
126 }
127
128 return 0;
129}
130
131/*
132 * determine the length of a string in romfs on a block device
133 */
134static ssize_t romfs_blk_strnlen(struct super_block *sb,
135 unsigned long pos, size_t limit)
136{
137 struct buffer_head *bh;
138 unsigned long offset;
139 ssize_t n = 0;
140 size_t segment;
141 u_char *buf, *p;
142
143 /* scan the string up to blocksize bytes at a time */
144 while (limit > 0) {
145 offset = pos & (ROMBSIZE - 1);
146 segment = min_t(size_t, limit, ROMBSIZE - offset);
147 bh = sb_bread(sb, pos >> ROMBSBITS);
148 if (!bh)
149 return -EIO;
150 buf = bh->b_data + offset;
151 p = memchr(buf, 0, segment);
152 brelse(bh);
153 if (p)
154 return n + (p - buf);
155 limit -= segment;
156 pos += segment;
157 n += segment;
158 }
159
160 return n;
161}
162
163/*
164 * compare a string to one in a romfs image on a block device
165 * - return 1 if matched, 0 if differ, -ve if error
166 */
David Howells84baf742009-04-23 16:41:13 +0100167static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos,
168 const char *str, size_t size)
David Howellsda4458b2009-02-12 10:40:10 +0000169{
170 struct buffer_head *bh;
171 unsigned long offset;
172 size_t segment;
David Howells84baf742009-04-23 16:41:13 +0100173 bool matched, terminated = false;
David Howellsda4458b2009-02-12 10:40:10 +0000174
David Howells84baf742009-04-23 16:41:13 +0100175 /* compare string up to a block at a time */
David Howellsda4458b2009-02-12 10:40:10 +0000176 while (size > 0) {
177 offset = pos & (ROMBSIZE - 1);
178 segment = min_t(size_t, size, ROMBSIZE - offset);
179 bh = sb_bread(sb, pos >> ROMBSBITS);
180 if (!bh)
181 return -EIO;
David Howells84baf742009-04-23 16:41:13 +0100182 matched = (memcmp(bh->b_data + offset, str, segment) == 0);
183
David Howellsda4458b2009-02-12 10:40:10 +0000184 size -= segment;
185 pos += segment;
186 str += segment;
David Howells84baf742009-04-23 16:41:13 +0100187 if (matched && size == 0 && offset + segment < ROMBSIZE) {
188 if (!bh->b_data[offset + segment])
189 terminated = true;
190 else
191 matched = false;
192 }
193 brelse(bh);
194 if (!matched)
195 return 0;
196 }
197
198 if (!terminated) {
199 /* the terminating NUL must be on the first byte of the next
200 * block */
201 BUG_ON((pos & (ROMBSIZE - 1)) != 0);
202 bh = sb_bread(sb, pos >> ROMBSBITS);
203 if (!bh)
204 return -EIO;
205 matched = !bh->b_data[0];
206 brelse(bh);
207 if (!matched)
208 return 0;
David Howellsda4458b2009-02-12 10:40:10 +0000209 }
210
211 return 1;
212}
213#endif /* CONFIG_ROMFS_ON_BLOCK */
214
215/*
216 * read data from the romfs image
217 */
218int romfs_dev_read(struct super_block *sb, unsigned long pos,
219 void *buf, size_t buflen)
220{
221 size_t limit;
222
223 limit = romfs_maxsize(sb);
224 if (pos >= limit)
225 return -EIO;
226 if (buflen > limit - pos)
227 buflen = limit - pos;
228
229#ifdef CONFIG_ROMFS_ON_MTD
230 if (sb->s_mtd)
231 return romfs_mtd_read(sb, pos, buf, buflen);
232#endif
233#ifdef CONFIG_ROMFS_ON_BLOCK
234 if (sb->s_bdev)
235 return romfs_blk_read(sb, pos, buf, buflen);
236#endif
237 return -EIO;
238}
239
240/*
241 * determine the length of a string in romfs
242 */
243ssize_t romfs_dev_strnlen(struct super_block *sb,
244 unsigned long pos, size_t maxlen)
245{
246 size_t limit;
247
248 limit = romfs_maxsize(sb);
249 if (pos >= limit)
250 return -EIO;
251 if (maxlen > limit - pos)
252 maxlen = limit - pos;
253
254#ifdef CONFIG_ROMFS_ON_MTD
255 if (sb->s_mtd)
Bernd Schmidtef1f7a72009-10-06 09:55:26 +0100256 return romfs_mtd_strnlen(sb, pos, maxlen);
David Howellsda4458b2009-02-12 10:40:10 +0000257#endif
258#ifdef CONFIG_ROMFS_ON_BLOCK
259 if (sb->s_bdev)
Bernd Schmidtef1f7a72009-10-06 09:55:26 +0100260 return romfs_blk_strnlen(sb, pos, maxlen);
David Howellsda4458b2009-02-12 10:40:10 +0000261#endif
262 return -EIO;
263}
264
265/*
266 * compare a string to one in romfs
David Howells84baf742009-04-23 16:41:13 +0100267 * - the string to be compared to, str, may not be NUL-terminated; instead the
268 * string is of the specified size
David Howellsda4458b2009-02-12 10:40:10 +0000269 * - return 1 if matched, 0 if differ, -ve if error
270 */
David Howells84baf742009-04-23 16:41:13 +0100271int romfs_dev_strcmp(struct super_block *sb, unsigned long pos,
272 const char *str, size_t size)
David Howellsda4458b2009-02-12 10:40:10 +0000273{
274 size_t limit;
275
276 limit = romfs_maxsize(sb);
277 if (pos >= limit)
278 return -EIO;
279 if (size > ROMFS_MAXFN)
280 return -ENAMETOOLONG;
David Howells84baf742009-04-23 16:41:13 +0100281 if (size + 1 > limit - pos)
David Howellsda4458b2009-02-12 10:40:10 +0000282 return -EIO;
283
284#ifdef CONFIG_ROMFS_ON_MTD
285 if (sb->s_mtd)
David Howells84baf742009-04-23 16:41:13 +0100286 return romfs_mtd_strcmp(sb, pos, str, size);
David Howellsda4458b2009-02-12 10:40:10 +0000287#endif
288#ifdef CONFIG_ROMFS_ON_BLOCK
289 if (sb->s_bdev)
David Howells84baf742009-04-23 16:41:13 +0100290 return romfs_blk_strcmp(sb, pos, str, size);
David Howellsda4458b2009-02-12 10:40:10 +0000291#endif
292 return -EIO;
293}