294 lines
6.4 KiB
C
294 lines
6.4 KiB
C
/* RomFS storage access routines
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*
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* Copyright © 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/fs.h>
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#include <linux/mtd/super.h>
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#include <linux/buffer_head.h>
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#include "internal.h"
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#if !defined(CONFIG_ROMFS_ON_MTD) && !defined(CONFIG_ROMFS_ON_BLOCK)
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#error no ROMFS backing store interface configured
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#endif
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#ifdef CONFIG_ROMFS_ON_MTD
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#define ROMFS_MTD_READ(sb, ...) ((sb)->s_mtd->read((sb)->s_mtd, ##__VA_ARGS__))
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/*
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* read data from an romfs image on an MTD device
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*/
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static int romfs_mtd_read(struct super_block *sb, unsigned long pos,
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void *buf, size_t buflen)
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{
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size_t rlen;
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int ret;
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ret = ROMFS_MTD_READ(sb, pos, buflen, &rlen, buf);
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return (ret < 0 || rlen != buflen) ? -EIO : 0;
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}
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/*
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* determine the length of a string in a romfs image on an MTD device
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*/
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static ssize_t romfs_mtd_strnlen(struct super_block *sb,
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unsigned long pos, size_t maxlen)
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{
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ssize_t n = 0;
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size_t segment;
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u_char buf[16], *p;
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size_t len;
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int ret;
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/* scan the string up to 16 bytes at a time */
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while (maxlen > 0) {
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segment = min_t(size_t, maxlen, 16);
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ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
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if (ret < 0)
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return ret;
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p = memchr(buf, 0, len);
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if (p)
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return n + (p - buf);
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maxlen -= len;
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pos += len;
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n += len;
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}
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return n;
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}
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/*
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* compare a string to one in a romfs image on MTD
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* - return 1 if matched, 0 if differ, -ve if error
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*/
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static int romfs_mtd_strcmp(struct super_block *sb, unsigned long pos,
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const char *str, size_t size)
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{
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u_char buf[17];
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size_t len, segment;
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int ret;
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/* scan the string up to 16 bytes at a time, and attempt to grab the
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* trailing NUL whilst we're at it */
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buf[0] = 0xff;
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while (size > 0) {
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segment = min_t(size_t, size + 1, 17);
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ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
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if (ret < 0)
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return ret;
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len--;
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if (memcmp(buf, str, len) != 0)
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return 0;
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buf[0] = buf[len];
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size -= len;
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pos += len;
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str += len;
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}
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/* check the trailing NUL was */
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if (buf[0])
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return 0;
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return 1;
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}
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#endif /* CONFIG_ROMFS_ON_MTD */
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#ifdef CONFIG_ROMFS_ON_BLOCK
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/*
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* read data from an romfs image on a block device
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*/
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static int romfs_blk_read(struct super_block *sb, unsigned long pos,
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void *buf, size_t buflen)
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{
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struct buffer_head *bh;
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unsigned long offset;
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size_t segment;
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/* copy the string up to blocksize bytes at a time */
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while (buflen > 0) {
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offset = pos & (ROMBSIZE - 1);
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segment = min_t(size_t, buflen, ROMBSIZE - offset);
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bh = sb_bread(sb, pos >> ROMBSBITS);
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if (!bh)
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return -EIO;
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memcpy(buf, bh->b_data + offset, segment);
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brelse(bh);
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buf += segment;
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buflen -= segment;
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pos += segment;
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}
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return 0;
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}
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/*
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* determine the length of a string in romfs on a block device
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*/
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static ssize_t romfs_blk_strnlen(struct super_block *sb,
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unsigned long pos, size_t limit)
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{
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struct buffer_head *bh;
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unsigned long offset;
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ssize_t n = 0;
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size_t segment;
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u_char *buf, *p;
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/* scan the string up to blocksize bytes at a time */
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while (limit > 0) {
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offset = pos & (ROMBSIZE - 1);
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segment = min_t(size_t, limit, ROMBSIZE - offset);
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bh = sb_bread(sb, pos >> ROMBSBITS);
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if (!bh)
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return -EIO;
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buf = bh->b_data + offset;
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p = memchr(buf, 0, segment);
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brelse(bh);
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if (p)
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return n + (p - buf);
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limit -= segment;
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pos += segment;
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n += segment;
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}
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return n;
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}
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/*
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* compare a string to one in a romfs image on a block device
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* - return 1 if matched, 0 if differ, -ve if error
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*/
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static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos,
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const char *str, size_t size)
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{
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struct buffer_head *bh;
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unsigned long offset;
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size_t segment;
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bool matched, terminated = false;
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/* compare string up to a block at a time */
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while (size > 0) {
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offset = pos & (ROMBSIZE - 1);
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segment = min_t(size_t, size, ROMBSIZE - offset);
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bh = sb_bread(sb, pos >> ROMBSBITS);
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if (!bh)
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return -EIO;
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matched = (memcmp(bh->b_data + offset, str, segment) == 0);
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size -= segment;
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pos += segment;
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str += segment;
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if (matched && size == 0 && offset + segment < ROMBSIZE) {
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if (!bh->b_data[offset + segment])
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terminated = true;
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else
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matched = false;
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}
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brelse(bh);
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if (!matched)
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return 0;
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}
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if (!terminated) {
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/* the terminating NUL must be on the first byte of the next
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* block */
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BUG_ON((pos & (ROMBSIZE - 1)) != 0);
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bh = sb_bread(sb, pos >> ROMBSBITS);
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if (!bh)
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return -EIO;
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matched = !bh->b_data[0];
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brelse(bh);
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if (!matched)
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return 0;
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}
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return 1;
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}
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#endif /* CONFIG_ROMFS_ON_BLOCK */
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/*
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* read data from the romfs image
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*/
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int romfs_dev_read(struct super_block *sb, unsigned long pos,
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void *buf, size_t buflen)
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{
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size_t limit;
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limit = romfs_maxsize(sb);
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if (pos >= limit)
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return -EIO;
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if (buflen > limit - pos)
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buflen = limit - pos;
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#ifdef CONFIG_ROMFS_ON_MTD
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if (sb->s_mtd)
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return romfs_mtd_read(sb, pos, buf, buflen);
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#endif
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#ifdef CONFIG_ROMFS_ON_BLOCK
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if (sb->s_bdev)
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return romfs_blk_read(sb, pos, buf, buflen);
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#endif
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return -EIO;
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}
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/*
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* determine the length of a string in romfs
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*/
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ssize_t romfs_dev_strnlen(struct super_block *sb,
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unsigned long pos, size_t maxlen)
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{
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size_t limit;
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limit = romfs_maxsize(sb);
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if (pos >= limit)
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return -EIO;
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if (maxlen > limit - pos)
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maxlen = limit - pos;
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#ifdef CONFIG_ROMFS_ON_MTD
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if (sb->s_mtd)
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return romfs_mtd_strnlen(sb, pos, limit);
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#endif
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#ifdef CONFIG_ROMFS_ON_BLOCK
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if (sb->s_bdev)
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return romfs_blk_strnlen(sb, pos, limit);
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#endif
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return -EIO;
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}
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/*
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* compare a string to one in romfs
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* - the string to be compared to, str, may not be NUL-terminated; instead the
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* string is of the specified size
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* - return 1 if matched, 0 if differ, -ve if error
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*/
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int romfs_dev_strcmp(struct super_block *sb, unsigned long pos,
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const char *str, size_t size)
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{
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size_t limit;
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limit = romfs_maxsize(sb);
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if (pos >= limit)
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return -EIO;
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if (size > ROMFS_MAXFN)
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return -ENAMETOOLONG;
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if (size + 1 > limit - pos)
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return -EIO;
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#ifdef CONFIG_ROMFS_ON_MTD
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if (sb->s_mtd)
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return romfs_mtd_strcmp(sb, pos, str, size);
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#endif
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#ifdef CONFIG_ROMFS_ON_BLOCK
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if (sb->s_bdev)
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return romfs_blk_strcmp(sb, pos, str, size);
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#endif
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return -EIO;
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}
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