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/*

 * JFFS2 -- Journalling Flash File System, Version 2.

 *

 * Copyright (C) 2001, 2002 Red Hat, Inc.

 *

 * Created by David Woodhouse <dwmw2@cambridge.redhat.com>

 *

 * For licensing information, see the file 'LICENCE' in this directory.

 *

 * $Id: read.c,v 1.1.1.1 2004-02-14 13:29:20 phoenix Exp $

 *

 */

#include <linux/kernel.h>

#include <linux/slab.h>

#include <linux/crc32.h>

#include <linux/pagemap.h>

#include <linux/mtd/mtd.h>

#include "nodelist.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;

        uint32_t crc;

        unsigned char *decomprbuf = NULL;

        unsigned char *readbuf = NULL;

        int ret = 0;

        ri = jffs2_alloc_raw_inode();

        if (!ri)

                return -ENOMEM;

        ret = jffs2_flash_read(c, ref_offset(fd->raw), sizeof(*ri), &readlen, (char *)ri);

        if (ret) {

                jffs2_free_raw_inode(ri);

                printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", ref_offset(fd->raw), ret);

                return ret;

        }

        if (readlen != sizeof(*ri)) {

                jffs2_free_raw_inode(ri);

                printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%zx bytes, got 0x%zx\n",

                       ref_offset(fd->raw), 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",

                  ref_offset(fd->raw), je32_to_cpu(ri->node_crc),

                  crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),

                  je32_to_cpu(ri->offset), buf));

        if (crc != je32_to_cpu(ri->node_crc)) {

                printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",

                       je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));

                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 && !je32_to_cpu(ri->dsize) &&

            je32_to_cpu(ri->csize)) {

                ri->dsize = ri->csize;

                ri->csize = cpu_to_je32(0);

        }

        D1(if(ofs + len > je32_to_cpu(ri->dsize)) {

                printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",

                       len, ofs, je32_to_cpu(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 == je32_to_cpu(ri->dsize)) {

                readbuf = buf;

        } else {

                readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);

                if (!readbuf) {

                        ret = -ENOMEM;

                        goto out_ri;

                }

        }

        if (ri->compr != JFFS2_COMPR_NONE) {

                if (len < je32_to_cpu(ri->dsize)) {

                        decomprbuf = kmalloc(je32_to_cpu(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", je32_to_cpu(ri->csize),

                  readbuf));

        ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),

                               je32_to_cpu(ri->csize), &readlen, readbuf);

        if (!ret && readlen != je32_to_cpu(ri->csize))

                ret = -EIO;

        if (ret)

                goto out_decomprbuf;

        crc = crc32(0, readbuf, je32_to_cpu(ri->csize));

        if (crc != je32_to_cpu(ri->data_crc)) {

                printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n",

                       je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));

                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",

                          je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize), decomprbuf));

                ret = jffs2_decompress(ri->compr, readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));

                if (ret) {

                        printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);

                        goto out_decomprbuf;

                }

        }

        if (len < je32_to_cpu(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;

}

int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,

                           unsigned char *buf, uint32_t offset, uint32_t len)

{

        uint32_t end = offset + len;

        struct jffs2_node_frag *frag;

        int ret;

        D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",

                  f->inocache->ino, offset, offset+len));

        frag = jffs2_lookup_node_frag(&f->fragtree, offset);

        /* XXX FIXME: Where a single physical node actually shows up in two

           frags, we read it twice. Don't do that. */

        /* Now we're pointing at the first frag which overlaps our page */

        while(offset < end) {

                D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end));

                if (!frag || frag->ofs > offset) {

                        uint32_t holesize = end - offset;

                        if (frag) {

                                D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset));

                                holesize = min(holesize, frag->ofs - offset);

                                D1(jffs2_print_frag_list(f));

                        }

                        D1(printk(KERN_DEBUG "Filling non-frag hole from %d-%d\n", offset, offset+holesize));

                        memset(buf, 0, holesize);

                        buf += holesize;

                        offset += holesize;

                        continue;

                } else if (frag->ofs < offset && (offset & (PAGE_CACHE_SIZE-1)) != 0) {

                        D1(printk(KERN_NOTICE "Eep. Overlap in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n",

                                  f->inocache->ino, frag->ofs, offset));

                        D1(jffs2_print_frag_list(f));

                        memset(buf, 0, end - offset);

                        return -EIO;

                } else if (!frag->node) {

                        uint32_t holeend = min(end, frag->ofs + frag->size);

                        D1(printk(KERN_DEBUG "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n", offset, holeend, frag->ofs, frag->ofs + frag->size));

                        memset(buf, 0, holeend - offset);

                        buf += holeend - offset;

                        offset = holeend;

                        frag = frag_next(frag);

                        continue;

                } else {

                        uint32_t readlen;

                        uint32_t fragofs; /* offset within the frag to start reading */

                        fragofs = offset - frag->ofs;

                        readlen = min(frag->size - fragofs, end - offset);

                        D1(printk(KERN_DEBUG "Reading %d-%d from node at 0x%08x (%d)\n",

                                  frag->ofs+fragofs, frag->ofs+fragofs+readlen,

                                  ref_offset(frag->node->raw), ref_flags(frag->node->raw)));

                        ret = jffs2_read_dnode(c, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);

                        D2(printk(KERN_DEBUG "node read done\n"));

                        if (ret) {

                                D1(printk(KERN_DEBUG"jffs2_read_inode_range error %d\n",ret));

                                memset(buf, 0, readlen);

                                return ret;

                        }

                        buf += readlen;

                        offset += readlen;

                        frag = frag_next(frag);

                        D2(printk(KERN_DEBUG "node read was OK. Looping\n"));

                }

        }

        return 0;

}

/* Core function to read symlink target. */

char *jffs2_getlink(struct jffs2_sb_info *c, struct jffs2_inode_info *f)

{

        char *buf;

        int ret;

        down(&f->sem);

        if (!f->metadata) {

                printk(KERN_NOTICE "No metadata for symlink inode #%u\n", f->inocache->ino);

                up(&f->sem);

                return ERR_PTR(-EINVAL);

        }

        buf = kmalloc(f->metadata->size+1, GFP_USER);

        if (!buf) {

                up(&f->sem);

                return ERR_PTR(-ENOMEM);

        }

        buf[f->metadata->size]=0;

        ret = jffs2_read_dnode(c, f->metadata, buf, 0, f->metadata->size);

        up(&f->sem);

        if (ret) {

                kfree(buf);

                return ERR_PTR(ret);

        }

        return buf;

}