embox

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/*
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 * JFFS2 -- Journalling Flash File System, Version 2.
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 *
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 * Copyright (C) 2001-2003 Red Hat, Inc.
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 *
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 * Created by David Woodhouse <dwmw2@infradead.org>
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 *
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 * For licensing information, see the file 'LICENCE' in this directory.
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 *
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 * $Id: read.c,v 1.41 2005/07/22 10:32:08 dedekind 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/crc32.h>
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#include <linux/pagemap.h>
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#include <linux/mtd/mtd.h>
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#include <linux/compiler.h>
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#include "nodelist.h"
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#include "compr.h"
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int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
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		     struct jffs2_full_dnode *fd, unsigned char *buf,
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		     int ofs, int len) {
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	struct jffs2_raw_inode *ri;
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	size_t readlen;
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	uint32_t 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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	}
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	ret = jffs2_flash_read(c, ref_offset(fd->raw),
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			sizeof(*ri), &readlen, (unsigned 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", ref_offset(fd->raw), 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%zx bytes, got 0x%zx\n",
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		       ref_offset(fd->raw), 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( "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
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		  ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
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		  crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
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		  je32_to_cpu(ri->offset), buf));
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	if (crc != je32_to_cpu(ri->node_crc)) {
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		printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",
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		       je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
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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 && !je32_to_cpu(ri->dsize) &&
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	    je32_to_cpu(ri->csize)) {
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		ri->dsize = ri->csize;
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		ri->csize = cpu_to_je32(0);
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	}
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	D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
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		printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
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		       len, ofs, je32_to_cpu(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 == je32_to_cpu(ri->dsize)) {
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		readbuf = buf;
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	} else {
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		readbuf = kmalloc(je32_to_cpu(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 < je32_to_cpu(ri->dsize)) {
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			decomprbuf = kmalloc(je32_to_cpu(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( "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
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		  readbuf));
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	ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
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			       je32_to_cpu(ri->csize), &readlen, readbuf);
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	if (!ret && readlen != je32_to_cpu(ri->csize)) {
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		ret = -EIO;
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	}
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	if (ret) {
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		goto out_decomprbuf;
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	}
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	crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
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	if (crc != je32_to_cpu(ri->data_crc)) {
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		printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n",
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		       je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
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		ret = -EIO;
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		goto out_decomprbuf;
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	}
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	D2(printk( "Data CRC matches calculated CRC %08x\n", crc));
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	if (ri->compr != JFFS2_COMPR_NONE) {
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		D2(printk( "Decompress %d bytes from %p to %d bytes at %p\n",
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			  je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize), decomprbuf));
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		ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf,
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				decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(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 < je32_to_cpu(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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	}
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 out_readbuf:
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	if(readbuf != buf) {
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		kfree(readbuf);
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	}
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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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int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
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			   unsigned char *buf, uint32_t offset, uint32_t len)
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{
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	uint32_t end = offset + len;
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	struct jffs2_node_frag *frag;
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	int ret;
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	D1(printk( "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",
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		  f->inocache->ino, offset, offset + len));
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	frag = jffs2_lookup_node_frag(&f->fragtree, offset);
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	/* XXX FIXME: Where a single physical node actually shows up in two
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	   frags, we read it twice. Don't do that. */
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	/* Now we're pointing at the first frag which overlaps our page */
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	while(offset < end) {
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		D2(printk( "jffs2_read_inode_range: offset %d, end %d\n", offset, end));
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		if (unlikely(!frag || frag->ofs > offset)) {
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			uint32_t holesize = end - offset;
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			if (frag) {
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				D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset));
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				holesize = min(holesize, frag->ofs - offset);
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			}
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			D1(printk( "Filling non-frag hole from %d-%d\n", offset, offset+holesize));
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			memset(buf, 0, holesize);
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			buf += holesize;
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			offset += holesize;
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			continue;
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		} else if (unlikely(!frag->node)) {
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			uint32_t holeend = min(end, frag->ofs + frag->size);
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			D1(printk( "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n", offset, holeend, frag->ofs, frag->ofs + frag->size));
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			memset(buf, 0, holeend - offset);
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			buf += holeend - offset;
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			offset = holeend;
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			frag = frag_next(frag);
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			continue;
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		} else {
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			uint32_t readlen;
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			uint32_t fragofs; /* offset within the frag to start reading */
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			fragofs = offset - frag->ofs;
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			readlen = min(frag->size - fragofs, end - offset);
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			D1(printk( "Reading %d-%d from node at 0x%08x (%d)\n",
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				  frag->ofs + fragofs, frag->ofs + fragofs + readlen,
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				  ref_offset(frag->node->raw), ref_flags(frag->node->raw)));
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			ret = jffs2_read_dnode(c, f, frag->node, buf,
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					fragofs + frag->ofs - frag->node->ofs, readlen);
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			D2(printk( "node read done\n"));
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			if (ret) {
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				D1(printk("jffs2_read_inode_range error %d\n",ret));
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				memset(buf, 0, readlen);
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				return ret;
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			}
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			buf += readlen;
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			offset += readlen;
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			frag = frag_next(frag);
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			D2(printk( "node read was OK. Looping\n"));
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		}
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	}
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	return 0;
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}
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