diff options
Diffstat (limited to 'fs/romfs/storage.c')
-rw-r--r-- | fs/romfs/storage.c | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/fs/romfs/storage.c b/fs/romfs/storage.c new file mode 100644 index 00000000000..7e3e1e12a08 --- /dev/null +++ b/fs/romfs/storage.c @@ -0,0 +1,261 @@ +/* RomFS storage access routines + * + * Copyright © 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/fs.h> +#include <linux/mtd/super.h> +#include <linux/buffer_head.h> +#include "internal.h" + +#if !defined(CONFIG_ROMFS_ON_MTD) && !defined(CONFIG_ROMFS_ON_BLOCK) +#error no ROMFS backing store interface configured +#endif + +#ifdef CONFIG_ROMFS_ON_MTD +#define ROMFS_MTD_READ(sb, ...) ((sb)->s_mtd->read((sb)->s_mtd, ##__VA_ARGS__)) + +/* + * read data from an romfs image on an MTD device + */ +static int romfs_mtd_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen) +{ + size_t rlen; + int ret; + + ret = ROMFS_MTD_READ(sb, pos, buflen, &rlen, buf); + return (ret < 0 || rlen != buflen) ? -EIO : 0; +} + +/* + * determine the length of a string in a romfs image on an MTD device + */ +static ssize_t romfs_mtd_strnlen(struct super_block *sb, + unsigned long pos, size_t maxlen) +{ + ssize_t n = 0; + size_t segment; + u_char buf[16], *p; + size_t len; + int ret; + + /* scan the string up to 16 bytes at a time */ + while (maxlen > 0) { + segment = min_t(size_t, maxlen, 16); + ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf); + if (ret < 0) + return ret; + p = memchr(buf, 0, len); + if (p) + return n + (p - buf); + maxlen -= len; + pos += len; + n += len; + } + + return n; +} + +/* + * compare a string to one in a romfs image on MTD + * - return 1 if matched, 0 if differ, -ve if error + */ +static int romfs_mtd_strncmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size) +{ + u_char buf[16]; + size_t len, segment; + int ret; + + /* scan the string up to 16 bytes at a time */ + while (size > 0) { + segment = min_t(size_t, size, 16); + ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf); + if (ret < 0) + return ret; + if (memcmp(buf, str, len) != 0) + return 0; + size -= len; + pos += len; + str += len; + } + + return 1; +} +#endif /* CONFIG_ROMFS_ON_MTD */ + +#ifdef CONFIG_ROMFS_ON_BLOCK +/* + * read data from an romfs image on a block device + */ +static int romfs_blk_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen) +{ + struct buffer_head *bh; + unsigned long offset; + size_t segment; + + /* copy the string up to blocksize bytes at a time */ + while (buflen > 0) { + offset = pos & (ROMBSIZE - 1); + segment = min_t(size_t, buflen, ROMBSIZE - offset); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + memcpy(buf, bh->b_data + offset, segment); + brelse(bh); + buflen -= segment; + pos += segment; + } + + return 0; +} + +/* + * determine the length of a string in romfs on a block device + */ +static ssize_t romfs_blk_strnlen(struct super_block *sb, + unsigned long pos, size_t limit) +{ + struct buffer_head *bh; + unsigned long offset; + ssize_t n = 0; + size_t segment; + u_char *buf, *p; + + /* scan the string up to blocksize bytes at a time */ + while (limit > 0) { + offset = pos & (ROMBSIZE - 1); + segment = min_t(size_t, limit, ROMBSIZE - offset); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + buf = bh->b_data + offset; + p = memchr(buf, 0, segment); + brelse(bh); + if (p) + return n + (p - buf); + limit -= segment; + pos += segment; + n += segment; + } + + return n; +} + +/* + * compare a string to one in a romfs image on a block device + * - return 1 if matched, 0 if differ, -ve if error + */ +static int romfs_blk_strncmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size) +{ + struct buffer_head *bh; + unsigned long offset; + size_t segment; + bool x; + + /* scan the string up to 16 bytes at a time */ + while (size > 0) { + offset = pos & (ROMBSIZE - 1); + segment = min_t(size_t, size, ROMBSIZE - offset); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + x = (memcmp(bh->b_data + offset, str, segment) != 0); + brelse(bh); + if (x) + return 0; + size -= segment; + pos += segment; + str += segment; + } + + return 1; +} +#endif /* CONFIG_ROMFS_ON_BLOCK */ + +/* + * read data from the romfs image + */ +int romfs_dev_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen) +{ + size_t limit; + + limit = romfs_maxsize(sb); + if (pos >= limit) + return -EIO; + if (buflen > limit - pos) + buflen = limit - pos; + +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) + return romfs_mtd_read(sb, pos, buf, buflen); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) + return romfs_blk_read(sb, pos, buf, buflen); +#endif + return -EIO; +} + +/* + * determine the length of a string in romfs + */ +ssize_t romfs_dev_strnlen(struct super_block *sb, + unsigned long pos, size_t maxlen) +{ + size_t limit; + + limit = romfs_maxsize(sb); + if (pos >= limit) + return -EIO; + if (maxlen > limit - pos) + maxlen = limit - pos; + +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) + return romfs_mtd_strnlen(sb, pos, limit); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) + return romfs_blk_strnlen(sb, pos, limit); +#endif + return -EIO; +} + +/* + * compare a string to one in romfs + * - return 1 if matched, 0 if differ, -ve if error + */ +int romfs_dev_strncmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size) +{ + size_t limit; + + limit = romfs_maxsize(sb); + if (pos >= limit) + return -EIO; + if (size > ROMFS_MAXFN) + return -ENAMETOOLONG; + if (size > limit - pos) + return -EIO; + +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) + return romfs_mtd_strncmp(sb, pos, str, size); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) + return romfs_blk_strncmp(sb, pos, str, size); +#endif + return -EIO; +} |