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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* RomFS storage access routines
3 *
4 * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/fs.h>
9#include <linux/mtd/super.h>
10#include <linux/buffer_head.h>
11#include "internal.h"
12
13#if !defined(CONFIG_ROMFS_ON_MTD) && !defined(CONFIG_ROMFS_ON_BLOCK)
14#error no ROMFS backing store interface configured
15#endif
16
17#ifdef CONFIG_ROMFS_ON_MTD
18#define ROMFS_MTD_READ(sb, ...) mtd_read((sb)->s_mtd, ##__VA_ARGS__)
19
20/*
21 * read data from an romfs image on an MTD device
22 */
23static int romfs_mtd_read(struct super_block *sb, unsigned long pos,
24 void *buf, size_t buflen)
25{
26 size_t rlen;
27 int ret;
28
29 ret = ROMFS_MTD_READ(sb, pos, buflen, &rlen, buf);
30 return (ret < 0 || rlen != buflen) ? -EIO : 0;
31}
32
33/*
34 * determine the length of a string in a romfs image on an MTD device
35 */
36static ssize_t romfs_mtd_strnlen(struct super_block *sb,
37 unsigned long pos, size_t maxlen)
38{
39 ssize_t n = 0;
40 size_t segment;
41 u_char buf[16], *p;
42 size_t len;
43 int ret;
44
45 /* scan the string up to 16 bytes at a time */
46 while (maxlen > 0) {
47 segment = min_t(size_t, maxlen, 16);
48 ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
49 if (ret < 0)
50 return ret;
51 p = memchr(buf, 0, len);
52 if (p)
53 return n + (p - buf);
54 maxlen -= len;
55 pos += len;
56 n += len;
57 }
58
59 return n;
60}
61
62/*
63 * compare a string to one in a romfs image on MTD
64 * - return 1 if matched, 0 if differ, -ve if error
65 */
66static int romfs_mtd_strcmp(struct super_block *sb, unsigned long pos,
67 const char *str, size_t size)
68{
69 u_char buf[17];
70 size_t len, segment;
71 int ret;
72
73 /* scan the string up to 16 bytes at a time, and attempt to grab the
74 * trailing NUL whilst we're at it */
75 buf[0] = 0xff;
76
77 while (size > 0) {
78 segment = min_t(size_t, size + 1, 17);
79 ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
80 if (ret < 0)
81 return ret;
82 len--;
83 if (memcmp(buf, str, len) != 0)
84 return 0;
85 buf[0] = buf[len];
86 size -= len;
87 pos += len;
88 str += len;
89 }
90
91 /* check the trailing NUL was */
92 if (buf[0])
93 return 0;
94
95 return 1;
96}
97#endif /* CONFIG_ROMFS_ON_MTD */
98
99#ifdef CONFIG_ROMFS_ON_BLOCK
100/*
101 * read data from an romfs image on a block device
102 */
103static int romfs_blk_read(struct super_block *sb, unsigned long pos,
104 void *buf, size_t buflen)
105{
106 struct buffer_head *bh;
107 unsigned long offset;
108 size_t segment;
109
110 /* copy the string up to blocksize bytes at a time */
111 while (buflen > 0) {
112 offset = pos & (ROMBSIZE - 1);
113 segment = min_t(size_t, buflen, ROMBSIZE - offset);
114 bh = sb_bread(sb, pos >> ROMBSBITS);
115 if (!bh)
116 return -EIO;
117 memcpy(buf, bh->b_data + offset, segment);
118 brelse(bh);
119 buf += segment;
120 buflen -= segment;
121 pos += segment;
122 }
123
124 return 0;
125}
126
127/*
128 * determine the length of a string in romfs on a block device
129 */
130static ssize_t romfs_blk_strnlen(struct super_block *sb,
131 unsigned long pos, size_t limit)
132{
133 struct buffer_head *bh;
134 unsigned long offset;
135 ssize_t n = 0;
136 size_t segment;
137 u_char *buf, *p;
138
139 /* scan the string up to blocksize bytes at a time */
140 while (limit > 0) {
141 offset = pos & (ROMBSIZE - 1);
142 segment = min_t(size_t, limit, ROMBSIZE - offset);
143 bh = sb_bread(sb, pos >> ROMBSBITS);
144 if (!bh)
145 return -EIO;
146 buf = bh->b_data + offset;
147 p = memchr(buf, 0, segment);
148 brelse(bh);
149 if (p)
150 return n + (p - buf);
151 limit -= segment;
152 pos += segment;
153 n += segment;
154 }
155
156 return n;
157}
158
159/*
160 * compare a string to one in a romfs image on a block device
161 * - return 1 if matched, 0 if differ, -ve if error
162 */
163static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos,
164 const char *str, size_t size)
165{
166 struct buffer_head *bh;
167 unsigned long offset;
168 size_t segment;
169 bool matched, terminated = false;
170
171 /* compare string up to a block at a time */
172 while (size > 0) {
173 offset = pos & (ROMBSIZE - 1);
174 segment = min_t(size_t, size, ROMBSIZE - offset);
175 bh = sb_bread(sb, pos >> ROMBSBITS);
176 if (!bh)
177 return -EIO;
178 matched = (memcmp(bh->b_data + offset, str, segment) == 0);
179
180 size -= segment;
181 pos += segment;
182 str += segment;
183 if (matched && size == 0 && offset + segment < ROMBSIZE) {
184 if (!bh->b_data[offset + segment])
185 terminated = true;
186 else
187 matched = false;
188 }
189 brelse(bh);
190 if (!matched)
191 return 0;
192 }
193
194 if (!terminated) {
195 /* the terminating NUL must be on the first byte of the next
196 * block */
197 BUG_ON((pos & (ROMBSIZE - 1)) != 0);
198 bh = sb_bread(sb, pos >> ROMBSBITS);
199 if (!bh)
200 return -EIO;
201 matched = !bh->b_data[0];
202 brelse(bh);
203 if (!matched)
204 return 0;
205 }
206
207 return 1;
208}
209#endif /* CONFIG_ROMFS_ON_BLOCK */
210
211/*
212 * read data from the romfs image
213 */
214int romfs_dev_read(struct super_block *sb, unsigned long pos,
215 void *buf, size_t buflen)
216{
217 size_t limit;
218
219 limit = romfs_maxsize(sb);
220 if (pos >= limit || buflen > limit - pos)
221 return -EIO;
222
223#ifdef CONFIG_ROMFS_ON_MTD
224 if (sb->s_mtd)
225 return romfs_mtd_read(sb, pos, buf, buflen);
226#endif
227#ifdef CONFIG_ROMFS_ON_BLOCK
228 if (sb->s_bdev)
229 return romfs_blk_read(sb, pos, buf, buflen);
230#endif
231 return -EIO;
232}
233
234/*
235 * determine the length of a string in romfs
236 */
237ssize_t romfs_dev_strnlen(struct super_block *sb,
238 unsigned long pos, size_t maxlen)
239{
240 size_t limit;
241
242 limit = romfs_maxsize(sb);
243 if (pos >= limit)
244 return -EIO;
245 if (maxlen > limit - pos)
246 maxlen = limit - pos;
247
248#ifdef CONFIG_ROMFS_ON_MTD
249 if (sb->s_mtd)
250 return romfs_mtd_strnlen(sb, pos, maxlen);
251#endif
252#ifdef CONFIG_ROMFS_ON_BLOCK
253 if (sb->s_bdev)
254 return romfs_blk_strnlen(sb, pos, maxlen);
255#endif
256 return -EIO;
257}
258
259/*
260 * compare a string to one in romfs
261 * - the string to be compared to, str, may not be NUL-terminated; instead the
262 * string is of the specified size
263 * - return 1 if matched, 0 if differ, -ve if error
264 */
265int romfs_dev_strcmp(struct super_block *sb, unsigned long pos,
266 const char *str, size_t size)
267{
268 size_t limit;
269
270 limit = romfs_maxsize(sb);
271 if (pos >= limit)
272 return -EIO;
273 if (size > ROMFS_MAXFN)
274 return -ENAMETOOLONG;
275 if (size + 1 > limit - pos)
276 return -EIO;
277
278#ifdef CONFIG_ROMFS_ON_MTD
279 if (sb->s_mtd)
280 return romfs_mtd_strcmp(sb, pos, str, size);
281#endif
282#ifdef CONFIG_ROMFS_ON_BLOCK
283 if (sb->s_bdev)
284 return romfs_blk_strcmp(sb, pos, str, size);
285#endif
286 return -EIO;
287}
1/* 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
22#define ROMFS_MTD_READ(sb, ...) mtd_read((sb)->s_mtd, ##__VA_ARGS__)
23
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 */
70static int romfs_mtd_strcmp(struct super_block *sb, unsigned long pos,
71 const char *str, size_t size)
72{
73 u_char buf[17];
74 size_t len, segment;
75 int ret;
76
77 /* 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
81 while (size > 0) {
82 segment = min_t(size_t, size + 1, 17);
83 ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
84 if (ret < 0)
85 return ret;
86 len--;
87 if (memcmp(buf, str, len) != 0)
88 return 0;
89 buf[0] = buf[len];
90 size -= len;
91 pos += len;
92 str += len;
93 }
94
95 /* check the trailing NUL was */
96 if (buf[0])
97 return 0;
98
99 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);
123 buf += segment;
124 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 */
167static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos,
168 const char *str, size_t size)
169{
170 struct buffer_head *bh;
171 unsigned long offset;
172 size_t segment;
173 bool matched, terminated = false;
174
175 /* compare string up to a block at a time */
176 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;
182 matched = (memcmp(bh->b_data + offset, str, segment) == 0);
183
184 size -= segment;
185 pos += segment;
186 str += segment;
187 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;
209 }
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)
256 return romfs_mtd_strnlen(sb, pos, maxlen);
257#endif
258#ifdef CONFIG_ROMFS_ON_BLOCK
259 if (sb->s_bdev)
260 return romfs_blk_strnlen(sb, pos, maxlen);
261#endif
262 return -EIO;
263}
264
265/*
266 * compare a string to one in romfs
267 * - the string to be compared to, str, may not be NUL-terminated; instead the
268 * string is of the specified size
269 * - return 1 if matched, 0 if differ, -ve if error
270 */
271int romfs_dev_strcmp(struct super_block *sb, unsigned long pos,
272 const char *str, size_t size)
273{
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;
281 if (size + 1 > limit - pos)
282 return -EIO;
283
284#ifdef CONFIG_ROMFS_ON_MTD
285 if (sb->s_mtd)
286 return romfs_mtd_strcmp(sb, pos, str, size);
287#endif
288#ifdef CONFIG_ROMFS_ON_BLOCK
289 if (sb->s_bdev)
290 return romfs_blk_strcmp(sb, pos, str, size);
291#endif
292 return -EIO;
293}