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1275 |
phoenix |
/*
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* JFFS2 -- Journalling Flash File System, Version 2.
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*
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* Copyright (C) 2001 Red Hat, Inc.
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*
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* Created by David Woodhouse <dwmw2@cambridge.redhat.com>
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*
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* The original JFFS, from which the design for JFFS2 was derived,
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* was designed and implemented by Axis Communications AB.
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*
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* The contents of this file are subject to the Red Hat eCos Public
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* License Version 1.1 (the "Licence"); you may not use this file
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* except in compliance with the Licence. You may obtain a copy of
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* the Licence at http://www.redhat.com/
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*
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* Software distributed under the Licence is distributed on an "AS IS"
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* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
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* See the Licence for the specific language governing rights and
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* limitations under the Licence.
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*
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* The Original Code is JFFS2 - Journalling Flash File System, version 2
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*
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* Alternatively, the contents of this file may be used under the
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* terms of the GNU General Public License version 2 (the "GPL"), in
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* which case the provisions of the GPL are applicable instead of the
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* above. If you wish to allow the use of your version of this file
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* only under the terms of the GPL and not to allow others to use your
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* version of this file under the RHEPL, indicate your decision by
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* deleting the provisions above and replace them with the notice and
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* other provisions required by the GPL. If you do not delete the
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* provisions above, a recipient may use your version of this file
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* under either the RHEPL or the GPL.
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*
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* $Id: read.c,v 1.1.1.1 2004-04-15 01:11:07 phoenix Exp $
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*
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/jffs2.h>
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#include <linux/mtd/mtd.h>
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#include "nodelist.h"
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#include <linux/crc32.h>
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int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_full_dnode *fd, unsigned char *buf, int ofs, int len)
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{
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struct jffs2_raw_inode *ri;
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size_t readlen;
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__u32 crc;
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unsigned char *decomprbuf = NULL;
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unsigned char *readbuf = NULL;
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int ret = 0;
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ri = jffs2_alloc_raw_inode();
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if (!ri)
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return -ENOMEM;
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ret = c->mtd->read(c->mtd, fd->raw->flash_offset & ~3, sizeof(*ri), &readlen, (char *)ri);
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if (ret) {
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jffs2_free_raw_inode(ri);
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printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", fd->raw->flash_offset & ~3, ret);
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return ret;
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}
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if (readlen != sizeof(*ri)) {
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jffs2_free_raw_inode(ri);
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printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%x bytes, got 0x%x\n",
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fd->raw->flash_offset & ~3, sizeof(*ri), readlen);
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return -EIO;
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}
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crc = crc32(0, ri, sizeof(*ri)-8);
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D1(printk(KERN_DEBUG "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n", fd->raw->flash_offset & ~3, ri->node_crc, crc, ri->dsize, ri->csize, ri->offset, buf));
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if (crc != ri->node_crc) {
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printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n", ri->node_crc, crc, fd->raw->flash_offset & ~3);
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ret = -EIO;
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goto out_ri;
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}
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/* There was a bug where we wrote hole nodes out with csize/dsize
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swapped. Deal with it */
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if (ri->compr == JFFS2_COMPR_ZERO && !ri->dsize && ri->csize) {
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ri->dsize = ri->csize;
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ri->csize = 0;
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}
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D1(if(ofs + len > ri->dsize) {
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printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n", len, ofs, ri->dsize);
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ret = -EINVAL;
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goto out_ri;
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});
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if (ri->compr == JFFS2_COMPR_ZERO) {
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memset(buf, 0, len);
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goto out_ri;
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}
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/* Cases:
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Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
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Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
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Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
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Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
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*/
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if (ri->compr == JFFS2_COMPR_NONE && len == ri->dsize) {
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readbuf = buf;
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} else {
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readbuf = kmalloc(ri->csize, GFP_KERNEL);
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if (!readbuf) {
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ret = -ENOMEM;
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goto out_ri;
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}
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}
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if (ri->compr != JFFS2_COMPR_NONE) {
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if (len < ri->dsize) {
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decomprbuf = kmalloc(ri->dsize, GFP_KERNEL);
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if (!decomprbuf) {
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ret = -ENOMEM;
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goto out_readbuf;
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}
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} else {
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decomprbuf = buf;
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}
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} else {
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decomprbuf = readbuf;
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}
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D2(printk(KERN_DEBUG "Read %d bytes to %p\n", ri->csize, readbuf));
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ret = c->mtd->read(c->mtd, (fd->raw->flash_offset &~3) + sizeof(*ri), ri->csize, &readlen, readbuf);
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if (!ret && readlen != ri->csize)
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ret = -EIO;
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if (ret)
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goto out_decomprbuf;
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crc = crc32(0, readbuf, ri->csize);
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if (crc != ri->data_crc) {
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printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n", ri->data_crc, crc, fd->raw->flash_offset & ~3);
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ret = -EIO;
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goto out_decomprbuf;
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}
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D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
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if (ri->compr != JFFS2_COMPR_NONE) {
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D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n", ri->csize, readbuf, ri->dsize, decomprbuf));
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ret = jffs2_decompress(ri->compr, readbuf, decomprbuf, ri->csize, ri->dsize);
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if (ret) {
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printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
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goto out_decomprbuf;
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}
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}
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if (len < ri->dsize) {
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memcpy(buf, decomprbuf+ofs, len);
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}
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out_decomprbuf:
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if(decomprbuf != buf && decomprbuf != readbuf)
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kfree(decomprbuf);
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out_readbuf:
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if(readbuf != buf)
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kfree(readbuf);
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out_ri:
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jffs2_free_raw_inode(ri);
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return ret;
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}
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