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/*
* JFFS2 -- Journalling Flash File System, Version 2.
*
* Copyright (C) 2001 Red Hat, Inc.
*
* Created by David Woodhouse <dwmw2@cambridge.redhat.com>
*
* The original JFFS, from which the design for JFFS2 was derived,
* was designed and implemented by Axis Communications AB.
*
* The contents of this file are subject to the Red Hat eCos Public
* License Version 1.1 (the "Licence"); you may not use this file
* except in compliance with the Licence. You may obtain a copy of
* the Licence at http://www.redhat.com/
*
* Software distributed under the Licence is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
* See the Licence for the specific language governing rights and
* limitations under the Licence.
*
* The Original Code is JFFS2 - Journalling Flash File System, version 2
*
* Alternatively, the contents of this file may be used under the
* terms of the GNU General Public License version 2 (the "GPL"), in
* which case the provisions of the GPL are applicable instead of the
* above. If you wish to allow the use of your version of this file
* only under the terms of the GPL and not to allow others to use your
* version of this file under the RHEPL, indicate your decision by
* deleting the provisions above and replace them with the notice and
* other provisions required by the GPL. If you do not delete the
* provisions above, a recipient may use your version of this file
* under either the RHEPL or the GPL.
*
* $Id: read.c,v 1.13.2.1 2002/02/01 23:32:33 dwmw2 Exp $
*
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/jffs2.h>
#include <linux/mtd/mtd.h>
#include "nodelist.h"
#include "crc32.h"
int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_full_dnode *fd, unsigned char *buf, int ofs, int len)
{
struct jffs2_raw_inode *ri;
size_t readlen;
__u32 crc;
unsigned char *decomprbuf = NULL;
unsigned char *readbuf = NULL;
int ret = 0;
ri = jffs2_alloc_raw_inode();
if (!ri)
return -ENOMEM;
ret = c->mtd->read(c->mtd, fd->raw->flash_offset & ~3, sizeof(*ri), &readlen, (char *)ri);
if (ret) {
jffs2_free_raw_inode(ri);
printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", fd->raw->flash_offset & ~3, ret);
return ret;
}
if (readlen != sizeof(*ri)) {
jffs2_free_raw_inode(ri);
printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%x bytes, got 0x%x\n",
fd->raw->flash_offset & ~3, sizeof(*ri), readlen);
return -EIO;
}
crc = crc32(0, ri, sizeof(*ri)-8);
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));
if (crc != ri->node_crc) {
printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n", ri->node_crc, crc, fd->raw->flash_offset & ~3);
ret = -EIO;
goto out_ri;
}
/* There was a bug where we wrote hole nodes out with csize/dsize
swapped. Deal with it */
if (ri->compr == JFFS2_COMPR_ZERO && !ri->dsize && ri->csize) {
ri->dsize = ri->csize;
ri->csize = 0;
}
D1(if(ofs + len > ri->dsize) {
printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n", len, ofs, ri->dsize);
ret = -EINVAL;
goto out_ri;
});
if (ri->compr == JFFS2_COMPR_ZERO) {
memset(buf, 0, len);
goto out_ri;
}
/* Cases:
Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
*/
if (ri->compr == JFFS2_COMPR_NONE && len == ri->dsize) {
readbuf = buf;
} else {
readbuf = kmalloc(ri->csize, GFP_KERNEL);
if (!readbuf) {
ret = -ENOMEM;
goto out_ri;
}
}
if (ri->compr != JFFS2_COMPR_NONE) {
if (len < ri->dsize) {
decomprbuf = kmalloc(ri->dsize, GFP_KERNEL);
if (!decomprbuf) {
ret = -ENOMEM;
goto out_readbuf;
}
} else {
decomprbuf = buf;
}
} else {
decomprbuf = readbuf;
}
D2(printk(KERN_DEBUG "Read %d bytes to %p\n", ri->csize, readbuf));
ret = c->mtd->read(c->mtd, (fd->raw->flash_offset &~3) + sizeof(*ri), ri->csize, &readlen, readbuf);
if (!ret && readlen != ri->csize)
ret = -EIO;
if (ret)
goto out_decomprbuf;
crc = crc32(0, readbuf, ri->csize);
if (crc != ri->data_crc) {
printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n", ri->data_crc, crc, fd->raw->flash_offset & ~3);
ret = -EIO;
goto out_decomprbuf;
}
D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
if (ri->compr != JFFS2_COMPR_NONE) {
D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n", ri->csize, readbuf, ri->dsize, decomprbuf));
ret = jffs2_decompress(ri->compr, readbuf, decomprbuf, ri->csize, ri->dsize);
if (ret) {
printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
goto out_decomprbuf;
}
}
if (len < ri->dsize) {
memcpy(buf, decomprbuf+ofs, len);
}
out_decomprbuf:
if(decomprbuf != buf && decomprbuf != readbuf)
kfree(decomprbuf);
out_readbuf:
if(readbuf != buf)
kfree(readbuf);
out_ri:
jffs2_free_raw_inode(ri);
return ret;
}
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