/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/crc32.h>
#include <linux/pagemap.h>
#include <linux/mtd/mtd.h>
#include <linux/compiler.h>
#include "nodelist.h"
#include "compr.h"

int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
                     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);
                pr_warn("Error reading node from 0x%08x: %d\n",
                        ref_offset(fd->raw), ret);
                return ret;
        }
        if (readlen != sizeof(*ri)) {
                jffs2_free_raw_inode(ri);
                pr_warn("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);

        jffs2_dbg(1, "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)) {
                pr_warn("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)) {
                        pr_warn("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;
        }

        jffs2_dbg(2, "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)) {
                pr_warn("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;
        }
        jffs2_dbg(2, "Data CRC matches calculated CRC %08x\n", crc);
        if (ri->compr != JFFS2_COMPR_NONE) {
                jffs2_dbg(2, "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(c, f, ri->compr | (ri->usercompr << 8), readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
                if (ret) {
                        pr_warn("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;

        jffs2_dbg(1, "%s(): ino #%u, range 0x%08x-0x%08x\n",
                  __func__, 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
         * (or perhaps is before it, if we've been asked to read off the
         * end of the file). */
        while(offset < end) {
                jffs2_dbg(2, "%s(): offset %d, end %d\n",
                          __func__, offset, end);
                if (unlikely(!frag || frag->ofs > offset ||
                             frag->ofs + frag->size <= offset)) {
                        uint32_t holesize = end - offset;
                        if (frag && frag->ofs > offset) {
                                jffs2_dbg(1, "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);
                        }
                        jffs2_dbg(1, "Filling non-frag hole from %d-%d\n",
                                  offset, offset + holesize);
                        memset(buf, 0, holesize);
                        buf += holesize;
                        offset += holesize;
                        continue;
                } else if (unlikely(!frag->node)) {
                        uint32_t holeend = min(end, frag->ofs + frag->size);
                        jffs2_dbg(1, "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);
                        jffs2_dbg(1, "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, f, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);
                        jffs2_dbg(2, "node read done\n");
                        if (ret) {
                                jffs2_dbg(1, "%s(): error %d\n",
                                          __func__, ret);
                                memset(buf, 0, readlen);
                                return ret;
                        }
                        buf += readlen;
                        offset += readlen;
                        frag = frag_next(frag);
                        jffs2_dbg(2, "node read was OK. Looping\n");
                }
        }
        return 0;
}