1
/* RomFS storage access routines
3
* Copyright © 2007 Red Hat, Inc. All Rights Reserved.
4
* Written by David Howells (dhowells@redhat.com)
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.
13
#include <linux/mtd/super.h>
14
#include <linux/buffer_head.h>
17
#if !defined(CONFIG_ROMFS_ON_MTD) && !defined(CONFIG_ROMFS_ON_BLOCK)
18
#error no ROMFS backing store interface configured
21
#ifdef CONFIG_ROMFS_ON_MTD
22
#define ROMFS_MTD_READ(sb, ...) ((sb)->s_mtd->read((sb)->s_mtd, ##__VA_ARGS__))
25
* read data from an romfs image on an MTD device
27
static int romfs_mtd_read(struct super_block *sb, unsigned long pos,
28
void *buf, size_t buflen)
33
ret = ROMFS_MTD_READ(sb, pos, buflen, &rlen, buf);
34
return (ret < 0 || rlen != buflen) ? -EIO : 0;
38
* determine the length of a string in a romfs image on an MTD device
40
static ssize_t romfs_mtd_strnlen(struct super_block *sb,
41
unsigned long pos, size_t maxlen)
49
/* scan the string up to 16 bytes at a time */
51
segment = min_t(size_t, maxlen, 16);
52
ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
55
p = memchr(buf, 0, len);
67
* compare a string to one in a romfs image on MTD
68
* - return 1 if matched, 0 if differ, -ve if error
70
static int romfs_mtd_strcmp(struct super_block *sb, unsigned long pos,
71
const char *str, size_t size)
77
/* scan the string up to 16 bytes at a time, and attempt to grab the
78
* trailing NUL whilst we're at it */
82
segment = min_t(size_t, size + 1, 17);
83
ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
87
if (memcmp(buf, str, len) != 0)
95
/* check the trailing NUL was */
101
#endif /* CONFIG_ROMFS_ON_MTD */
103
#ifdef CONFIG_ROMFS_ON_BLOCK
105
* read data from an romfs image on a block device
107
static int romfs_blk_read(struct super_block *sb, unsigned long pos,
108
void *buf, size_t buflen)
110
struct buffer_head *bh;
111
unsigned long offset;
114
/* copy the string up to blocksize bytes at a time */
116
offset = pos & (ROMBSIZE - 1);
117
segment = min_t(size_t, buflen, ROMBSIZE - offset);
118
bh = sb_bread(sb, pos >> ROMBSBITS);
121
memcpy(buf, bh->b_data + offset, segment);
132
* determine the length of a string in romfs on a block device
134
static ssize_t romfs_blk_strnlen(struct super_block *sb,
135
unsigned long pos, size_t limit)
137
struct buffer_head *bh;
138
unsigned long offset;
143
/* scan the string up to blocksize bytes at a time */
145
offset = pos & (ROMBSIZE - 1);
146
segment = min_t(size_t, limit, ROMBSIZE - offset);
147
bh = sb_bread(sb, pos >> ROMBSBITS);
150
buf = bh->b_data + offset;
151
p = memchr(buf, 0, segment);
154
return n + (p - buf);
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
167
static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos,
168
const char *str, size_t size)
170
struct buffer_head *bh;
171
unsigned long offset;
173
bool matched, terminated = false;
175
/* compare string up to a block at a time */
177
offset = pos & (ROMBSIZE - 1);
178
segment = min_t(size_t, size, ROMBSIZE - offset);
179
bh = sb_bread(sb, pos >> ROMBSBITS);
182
matched = (memcmp(bh->b_data + offset, str, segment) == 0);
187
if (matched && size == 0 && offset + segment < ROMBSIZE) {
188
if (!bh->b_data[offset + segment])
199
/* the terminating NUL must be on the first byte of the next
201
BUG_ON((pos & (ROMBSIZE - 1)) != 0);
202
bh = sb_bread(sb, pos >> ROMBSBITS);
205
matched = !bh->b_data[0];
213
#endif /* CONFIG_ROMFS_ON_BLOCK */
216
* read data from the romfs image
218
int romfs_dev_read(struct super_block *sb, unsigned long pos,
219
void *buf, size_t buflen)
223
limit = romfs_maxsize(sb);
226
if (buflen > limit - pos)
227
buflen = limit - pos;
229
#ifdef CONFIG_ROMFS_ON_MTD
231
return romfs_mtd_read(sb, pos, buf, buflen);
233
#ifdef CONFIG_ROMFS_ON_BLOCK
235
return romfs_blk_read(sb, pos, buf, buflen);
241
* determine the length of a string in romfs
243
ssize_t romfs_dev_strnlen(struct super_block *sb,
244
unsigned long pos, size_t maxlen)
248
limit = romfs_maxsize(sb);
251
if (maxlen > limit - pos)
252
maxlen = limit - pos;
254
#ifdef CONFIG_ROMFS_ON_MTD
256
return romfs_mtd_strnlen(sb, pos, limit);
258
#ifdef CONFIG_ROMFS_ON_BLOCK
260
return romfs_blk_strnlen(sb, pos, limit);
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
271
int romfs_dev_strcmp(struct super_block *sb, unsigned long pos,
272
const char *str, size_t size)
276
limit = romfs_maxsize(sb);
279
if (size > ROMFS_MAXFN)
280
return -ENAMETOOLONG;
281
if (size + 1 > limit - pos)
284
#ifdef CONFIG_ROMFS_ON_MTD
286
return romfs_mtd_strcmp(sb, pos, str, size);
288
#ifdef CONFIG_ROMFS_ON_BLOCK
290
return romfs_blk_strcmp(sb, pos, str, size);