1da4458bdSDavid Howells /* RomFS storage access routines 2da4458bdSDavid Howells * 3da4458bdSDavid Howells * Copyright © 2007 Red Hat, Inc. All Rights Reserved. 4da4458bdSDavid Howells * Written by David Howells (dhowells@redhat.com) 5da4458bdSDavid Howells * 6da4458bdSDavid Howells * This program is free software; you can redistribute it and/or 7da4458bdSDavid Howells * modify it under the terms of the GNU General Public License 8da4458bdSDavid Howells * as published by the Free Software Foundation; either version 9da4458bdSDavid Howells * 2 of the License, or (at your option) any later version. 10da4458bdSDavid Howells */ 11da4458bdSDavid Howells 12da4458bdSDavid Howells #include <linux/fs.h> 13da4458bdSDavid Howells #include <linux/mtd/super.h> 14da4458bdSDavid Howells #include <linux/buffer_head.h> 15da4458bdSDavid Howells #include "internal.h" 16da4458bdSDavid Howells 17da4458bdSDavid Howells #if !defined(CONFIG_ROMFS_ON_MTD) && !defined(CONFIG_ROMFS_ON_BLOCK) 18da4458bdSDavid Howells #error no ROMFS backing store interface configured 19da4458bdSDavid Howells #endif 20da4458bdSDavid Howells 21da4458bdSDavid Howells #ifdef CONFIG_ROMFS_ON_MTD 22da4458bdSDavid Howells #define ROMFS_MTD_READ(sb, ...) ((sb)->s_mtd->read((sb)->s_mtd, ##__VA_ARGS__)) 23da4458bdSDavid Howells 24da4458bdSDavid Howells /* 25da4458bdSDavid Howells * read data from an romfs image on an MTD device 26da4458bdSDavid Howells */ 27da4458bdSDavid Howells static int romfs_mtd_read(struct super_block *sb, unsigned long pos, 28da4458bdSDavid Howells void *buf, size_t buflen) 29da4458bdSDavid Howells { 30da4458bdSDavid Howells size_t rlen; 31da4458bdSDavid Howells int ret; 32da4458bdSDavid Howells 33da4458bdSDavid Howells ret = ROMFS_MTD_READ(sb, pos, buflen, &rlen, buf); 34da4458bdSDavid Howells return (ret < 0 || rlen != buflen) ? -EIO : 0; 35da4458bdSDavid Howells } 36da4458bdSDavid Howells 37da4458bdSDavid Howells /* 38da4458bdSDavid Howells * determine the length of a string in a romfs image on an MTD device 39da4458bdSDavid Howells */ 40da4458bdSDavid Howells static ssize_t romfs_mtd_strnlen(struct super_block *sb, 41da4458bdSDavid Howells unsigned long pos, size_t maxlen) 42da4458bdSDavid Howells { 43da4458bdSDavid Howells ssize_t n = 0; 44da4458bdSDavid Howells size_t segment; 45da4458bdSDavid Howells u_char buf[16], *p; 46da4458bdSDavid Howells size_t len; 47da4458bdSDavid Howells int ret; 48da4458bdSDavid Howells 49da4458bdSDavid Howells /* scan the string up to 16 bytes at a time */ 50da4458bdSDavid Howells while (maxlen > 0) { 51da4458bdSDavid Howells segment = min_t(size_t, maxlen, 16); 52da4458bdSDavid Howells ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf); 53da4458bdSDavid Howells if (ret < 0) 54da4458bdSDavid Howells return ret; 55da4458bdSDavid Howells p = memchr(buf, 0, len); 56da4458bdSDavid Howells if (p) 57da4458bdSDavid Howells return n + (p - buf); 58da4458bdSDavid Howells maxlen -= len; 59da4458bdSDavid Howells pos += len; 60da4458bdSDavid Howells n += len; 61da4458bdSDavid Howells } 62da4458bdSDavid Howells 63da4458bdSDavid Howells return n; 64da4458bdSDavid Howells } 65da4458bdSDavid Howells 66da4458bdSDavid Howells /* 67da4458bdSDavid Howells * compare a string to one in a romfs image on MTD 68da4458bdSDavid Howells * - return 1 if matched, 0 if differ, -ve if error 69da4458bdSDavid Howells */ 7084baf74bSDavid Howells static int romfs_mtd_strcmp(struct super_block *sb, unsigned long pos, 71da4458bdSDavid Howells const char *str, size_t size) 72da4458bdSDavid Howells { 7384baf74bSDavid Howells u_char buf[17]; 74da4458bdSDavid Howells size_t len, segment; 75da4458bdSDavid Howells int ret; 76da4458bdSDavid Howells 7784baf74bSDavid Howells /* scan the string up to 16 bytes at a time, and attempt to grab the 7884baf74bSDavid Howells * trailing NUL whilst we're at it */ 7984baf74bSDavid Howells buf[0] = 0xff; 8084baf74bSDavid Howells 81da4458bdSDavid Howells while (size > 0) { 8284baf74bSDavid Howells segment = min_t(size_t, size + 1, 17); 83da4458bdSDavid Howells ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf); 84da4458bdSDavid Howells if (ret < 0) 85da4458bdSDavid Howells return ret; 8684baf74bSDavid Howells len--; 87da4458bdSDavid Howells if (memcmp(buf, str, len) != 0) 88da4458bdSDavid Howells return 0; 8984baf74bSDavid Howells buf[0] = buf[len]; 90da4458bdSDavid Howells size -= len; 91da4458bdSDavid Howells pos += len; 92da4458bdSDavid Howells str += len; 93da4458bdSDavid Howells } 94da4458bdSDavid Howells 9584baf74bSDavid Howells /* check the trailing NUL was */ 9684baf74bSDavid Howells if (buf[0]) 9784baf74bSDavid Howells return 0; 9884baf74bSDavid Howells 99da4458bdSDavid Howells return 1; 100da4458bdSDavid Howells } 101da4458bdSDavid Howells #endif /* CONFIG_ROMFS_ON_MTD */ 102da4458bdSDavid Howells 103da4458bdSDavid Howells #ifdef CONFIG_ROMFS_ON_BLOCK 104da4458bdSDavid Howells /* 105da4458bdSDavid Howells * read data from an romfs image on a block device 106da4458bdSDavid Howells */ 107da4458bdSDavid Howells static int romfs_blk_read(struct super_block *sb, unsigned long pos, 108da4458bdSDavid Howells void *buf, size_t buflen) 109da4458bdSDavid Howells { 110da4458bdSDavid Howells struct buffer_head *bh; 111da4458bdSDavid Howells unsigned long offset; 112da4458bdSDavid Howells size_t segment; 113da4458bdSDavid Howells 114da4458bdSDavid Howells /* copy the string up to blocksize bytes at a time */ 115da4458bdSDavid Howells while (buflen > 0) { 116da4458bdSDavid Howells offset = pos & (ROMBSIZE - 1); 117da4458bdSDavid Howells segment = min_t(size_t, buflen, ROMBSIZE - offset); 118da4458bdSDavid Howells bh = sb_bread(sb, pos >> ROMBSBITS); 119da4458bdSDavid Howells if (!bh) 120da4458bdSDavid Howells return -EIO; 121da4458bdSDavid Howells memcpy(buf, bh->b_data + offset, segment); 122da4458bdSDavid Howells brelse(bh); 1234b2b0b97SDavid Howells buf += segment; 124da4458bdSDavid Howells buflen -= segment; 125da4458bdSDavid Howells pos += segment; 126da4458bdSDavid Howells } 127da4458bdSDavid Howells 128da4458bdSDavid Howells return 0; 129da4458bdSDavid Howells } 130da4458bdSDavid Howells 131da4458bdSDavid Howells /* 132da4458bdSDavid Howells * determine the length of a string in romfs on a block device 133da4458bdSDavid Howells */ 134da4458bdSDavid Howells static ssize_t romfs_blk_strnlen(struct super_block *sb, 135da4458bdSDavid Howells unsigned long pos, size_t limit) 136da4458bdSDavid Howells { 137da4458bdSDavid Howells struct buffer_head *bh; 138da4458bdSDavid Howells unsigned long offset; 139da4458bdSDavid Howells ssize_t n = 0; 140da4458bdSDavid Howells size_t segment; 141da4458bdSDavid Howells u_char *buf, *p; 142da4458bdSDavid Howells 143da4458bdSDavid Howells /* scan the string up to blocksize bytes at a time */ 144da4458bdSDavid Howells while (limit > 0) { 145da4458bdSDavid Howells offset = pos & (ROMBSIZE - 1); 146da4458bdSDavid Howells segment = min_t(size_t, limit, ROMBSIZE - offset); 147da4458bdSDavid Howells bh = sb_bread(sb, pos >> ROMBSBITS); 148da4458bdSDavid Howells if (!bh) 149da4458bdSDavid Howells return -EIO; 150da4458bdSDavid Howells buf = bh->b_data + offset; 151da4458bdSDavid Howells p = memchr(buf, 0, segment); 152da4458bdSDavid Howells brelse(bh); 153da4458bdSDavid Howells if (p) 154da4458bdSDavid Howells return n + (p - buf); 155da4458bdSDavid Howells limit -= segment; 156da4458bdSDavid Howells pos += segment; 157da4458bdSDavid Howells n += segment; 158da4458bdSDavid Howells } 159da4458bdSDavid Howells 160da4458bdSDavid Howells return n; 161da4458bdSDavid Howells } 162da4458bdSDavid Howells 163da4458bdSDavid Howells /* 164da4458bdSDavid Howells * compare a string to one in a romfs image on a block device 165da4458bdSDavid Howells * - return 1 if matched, 0 if differ, -ve if error 166da4458bdSDavid Howells */ 16784baf74bSDavid Howells static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos, 168da4458bdSDavid Howells const char *str, size_t size) 169da4458bdSDavid Howells { 170da4458bdSDavid Howells struct buffer_head *bh; 171da4458bdSDavid Howells unsigned long offset; 172da4458bdSDavid Howells size_t segment; 17384baf74bSDavid Howells bool matched, terminated = false; 174da4458bdSDavid Howells 17584baf74bSDavid Howells /* compare string up to a block at a time */ 176da4458bdSDavid Howells while (size > 0) { 177da4458bdSDavid Howells offset = pos & (ROMBSIZE - 1); 178da4458bdSDavid Howells segment = min_t(size_t, size, ROMBSIZE - offset); 179da4458bdSDavid Howells bh = sb_bread(sb, pos >> ROMBSBITS); 180da4458bdSDavid Howells if (!bh) 181da4458bdSDavid Howells return -EIO; 18284baf74bSDavid Howells matched = (memcmp(bh->b_data + offset, str, segment) == 0); 18384baf74bSDavid Howells 184da4458bdSDavid Howells size -= segment; 185da4458bdSDavid Howells pos += segment; 186da4458bdSDavid Howells str += segment; 18784baf74bSDavid Howells if (matched && size == 0 && offset + segment < ROMBSIZE) { 18884baf74bSDavid Howells if (!bh->b_data[offset + segment]) 18984baf74bSDavid Howells terminated = true; 19084baf74bSDavid Howells else 19184baf74bSDavid Howells matched = false; 19284baf74bSDavid Howells } 19384baf74bSDavid Howells brelse(bh); 19484baf74bSDavid Howells if (!matched) 19584baf74bSDavid Howells return 0; 19684baf74bSDavid Howells } 19784baf74bSDavid Howells 19884baf74bSDavid Howells if (!terminated) { 19984baf74bSDavid Howells /* the terminating NUL must be on the first byte of the next 20084baf74bSDavid Howells * block */ 20184baf74bSDavid Howells BUG_ON((pos & (ROMBSIZE - 1)) != 0); 20284baf74bSDavid Howells bh = sb_bread(sb, pos >> ROMBSBITS); 20384baf74bSDavid Howells if (!bh) 20484baf74bSDavid Howells return -EIO; 20584baf74bSDavid Howells matched = !bh->b_data[0]; 20684baf74bSDavid Howells brelse(bh); 20784baf74bSDavid Howells if (!matched) 20884baf74bSDavid Howells return 0; 209da4458bdSDavid Howells } 210da4458bdSDavid Howells 211da4458bdSDavid Howells return 1; 212da4458bdSDavid Howells } 213da4458bdSDavid Howells #endif /* CONFIG_ROMFS_ON_BLOCK */ 214da4458bdSDavid Howells 215da4458bdSDavid Howells /* 216da4458bdSDavid Howells * read data from the romfs image 217da4458bdSDavid Howells */ 218da4458bdSDavid Howells int romfs_dev_read(struct super_block *sb, unsigned long pos, 219da4458bdSDavid Howells void *buf, size_t buflen) 220da4458bdSDavid Howells { 221da4458bdSDavid Howells size_t limit; 222da4458bdSDavid Howells 223da4458bdSDavid Howells limit = romfs_maxsize(sb); 224da4458bdSDavid Howells if (pos >= limit) 225da4458bdSDavid Howells return -EIO; 226da4458bdSDavid Howells if (buflen > limit - pos) 227da4458bdSDavid Howells buflen = limit - pos; 228da4458bdSDavid Howells 229da4458bdSDavid Howells #ifdef CONFIG_ROMFS_ON_MTD 230da4458bdSDavid Howells if (sb->s_mtd) 231da4458bdSDavid Howells return romfs_mtd_read(sb, pos, buf, buflen); 232da4458bdSDavid Howells #endif 233da4458bdSDavid Howells #ifdef CONFIG_ROMFS_ON_BLOCK 234da4458bdSDavid Howells if (sb->s_bdev) 235da4458bdSDavid Howells return romfs_blk_read(sb, pos, buf, buflen); 236da4458bdSDavid Howells #endif 237da4458bdSDavid Howells return -EIO; 238da4458bdSDavid Howells } 239da4458bdSDavid Howells 240da4458bdSDavid Howells /* 241da4458bdSDavid Howells * determine the length of a string in romfs 242da4458bdSDavid Howells */ 243da4458bdSDavid Howells ssize_t romfs_dev_strnlen(struct super_block *sb, 244da4458bdSDavid Howells unsigned long pos, size_t maxlen) 245da4458bdSDavid Howells { 246da4458bdSDavid Howells size_t limit; 247da4458bdSDavid Howells 248da4458bdSDavid Howells limit = romfs_maxsize(sb); 249da4458bdSDavid Howells if (pos >= limit) 250da4458bdSDavid Howells return -EIO; 251da4458bdSDavid Howells if (maxlen > limit - pos) 252da4458bdSDavid Howells maxlen = limit - pos; 253da4458bdSDavid Howells 254da4458bdSDavid Howells #ifdef CONFIG_ROMFS_ON_MTD 255da4458bdSDavid Howells if (sb->s_mtd) 256da4458bdSDavid Howells return romfs_mtd_strnlen(sb, pos, limit); 257da4458bdSDavid Howells #endif 258da4458bdSDavid Howells #ifdef CONFIG_ROMFS_ON_BLOCK 259da4458bdSDavid Howells if (sb->s_bdev) 260da4458bdSDavid Howells return romfs_blk_strnlen(sb, pos, limit); 261da4458bdSDavid Howells #endif 262da4458bdSDavid Howells return -EIO; 263da4458bdSDavid Howells } 264da4458bdSDavid Howells 265da4458bdSDavid Howells /* 266da4458bdSDavid Howells * compare a string to one in romfs 26784baf74bSDavid Howells * - the string to be compared to, str, may not be NUL-terminated; instead the 26884baf74bSDavid Howells * string is of the specified size 269da4458bdSDavid Howells * - return 1 if matched, 0 if differ, -ve if error 270da4458bdSDavid Howells */ 27184baf74bSDavid Howells int romfs_dev_strcmp(struct super_block *sb, unsigned long pos, 272da4458bdSDavid Howells const char *str, size_t size) 273da4458bdSDavid Howells { 274da4458bdSDavid Howells size_t limit; 275da4458bdSDavid Howells 276da4458bdSDavid Howells limit = romfs_maxsize(sb); 277da4458bdSDavid Howells if (pos >= limit) 278da4458bdSDavid Howells return -EIO; 279da4458bdSDavid Howells if (size > ROMFS_MAXFN) 280da4458bdSDavid Howells return -ENAMETOOLONG; 28184baf74bSDavid Howells if (size + 1 > limit - pos) 282da4458bdSDavid Howells return -EIO; 283da4458bdSDavid Howells 284da4458bdSDavid Howells #ifdef CONFIG_ROMFS_ON_MTD 285da4458bdSDavid Howells if (sb->s_mtd) 28684baf74bSDavid Howells return romfs_mtd_strcmp(sb, pos, str, size); 287da4458bdSDavid Howells #endif 288da4458bdSDavid Howells #ifdef CONFIG_ROMFS_ON_BLOCK 289da4458bdSDavid Howells if (sb->s_bdev) 29084baf74bSDavid Howells return romfs_blk_strcmp(sb, pos, str, size); 291da4458bdSDavid Howells #endif 292da4458bdSDavid Howells return -EIO; 293da4458bdSDavid Howells } 294