fs/jffs2/read.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright © 2001-2007 Red Hat, Inc.
   5  *
   6  * Created by David Woodhouse <dwmw2@infradead.org>
   7  *
   8  * For licensing information, see the file 'LICENCE' in this directory.
   9  *
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/kernel.h>
  15 #include <linux/slab.h>
  16 #include <linux/crc32.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/mtd/mtd.h>
  19 #include <linux/compiler.h>
  20 #include "nodelist.h"
  21 #include "compr.h"
  22
  23 int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
  24                      struct jffs2_full_dnode *fd, unsigned char *buf,
  25                      int ofs, int len)
  26 {
  27         struct jffs2_raw_inode *ri;
  28         size_t readlen;
  29         uint32_t crc;
  30         unsigned char *decomprbuf = NULL;
  31         unsigned char *readbuf = NULL;
  32         int ret = 0;
  33
  34         ri = jffs2_alloc_raw_inode();
  35         if (!ri)
  36                 return -ENOMEM;
  37
  38         ret = jffs2_flash_read(c, ref_offset(fd->raw), sizeof(*ri), &readlen, (char *)ri);
  39         if (ret) {
  40                 jffs2_free_raw_inode(ri);
  41                 pr_warn("Error reading node from 0x%08x: %d\n",
  42                         ref_offset(fd->raw), ret);
  43                 return ret;
  44         }
  45         if (readlen != sizeof(*ri)) {
  46                 jffs2_free_raw_inode(ri);
  47                 pr_warn("Short read from 0x%08x: wanted 0x%zx bytes, got 0x%zx\n",
  48                         ref_offset(fd->raw), sizeof(*ri), readlen);
  49                 return -EIO;
  50         }
  51         crc = crc32(0, ri, sizeof(*ri)-8);
  52
  53         jffs2_dbg(1, "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
  54                   ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
  55                   crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
  56                   je32_to_cpu(ri->offset), buf);
  57         if (crc != je32_to_cpu(ri->node_crc)) {
  58                 pr_warn("Node CRC %08x != calculated CRC %08x for node at %08x\n",
  59                         je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
  60                 ret = -EIO;
  61                 goto out_ri;
  62         }
  63         /* There was a bug where we wrote hole nodes out with csize/dsize
  64            swapped. Deal with it */
  65         if (ri->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(ri->dsize) &&
  66             je32_to_cpu(ri->csize)) {
  67                 ri->dsize = ri->csize;
  68                 ri->csize = cpu_to_je32(0);
  69         }
  70
  71         D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
  72                         pr_warn("jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
  73                                 len, ofs, je32_to_cpu(ri->dsize));
  74                 ret = -EINVAL;
  75                 goto out_ri;
  76         });
  77
  78
  79         if (ri->compr == JFFS2_COMPR_ZERO) {
  80                 memset(buf, 0, len);
  81                 goto out_ri;
  82         }
  83
  84         /* Cases:
  85            Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
  86            Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
  87            Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
  88            Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
  89         */
  90         if (ri->compr == JFFS2_COMPR_NONE && len == je32_to_cpu(ri->dsize)) {
  91                 readbuf = buf;
  92         } else {
  93                 readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
  94                 if (!readbuf) {
  95                         ret = -ENOMEM;
  96                         goto out_ri;
  97                 }
  98         }
  99         if (ri->compr != JFFS2_COMPR_NONE) {
 100                 if (len < je32_to_cpu(ri->dsize)) {
 101                         decomprbuf = kmalloc(je32_to_cpu(ri->dsize), GFP_KERNEL);
 102                         if (!decomprbuf) {
 103                                 ret = -ENOMEM;
 104                                 goto out_readbuf;
 105                         }
 106                 } else {
 107                         decomprbuf = buf;
 108                 }
 109         } else {
 110                 decomprbuf = readbuf;
 111         }
 112
 113         jffs2_dbg(2, "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
 114                   readbuf);
 115         ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
 116                                je32_to_cpu(ri->csize), &readlen, readbuf);
 117
 118         if (!ret && readlen != je32_to_cpu(ri->csize))
 119                 ret = -EIO;
 120         if (ret)
 121                 goto out_decomprbuf;
 122
 123         crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
 124         if (crc != je32_to_cpu(ri->data_crc)) {
 125                 pr_warn("Data CRC %08x != calculated CRC %08x for node at %08x\n",
 126                         je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
 127                 ret = -EIO;
 128                 goto out_decomprbuf;
 129         }
 130         jffs2_dbg(2, "Data CRC matches calculated CRC %08x\n", crc);
 131         if (ri->compr != JFFS2_COMPR_NONE) {
 132                 jffs2_dbg(2, "Decompress %d bytes from %p to %d bytes at %p\n",
 133                           je32_to_cpu(ri->csize), readbuf,
 134                           je32_to_cpu(ri->dsize), decomprbuf);
 135                 ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
 136                 if (ret) {
 137                         pr_warn("Error: jffs2_decompress returned %d\n", ret);
 138                         goto out_decomprbuf;
 139                 }
 140         }
 141
 142         if (len < je32_to_cpu(ri->dsize)) {
 143                 memcpy(buf, decomprbuf+ofs, len);
 144         }
 145  out_decomprbuf:
 146         if(decomprbuf != buf && decomprbuf != readbuf)
 147                 kfree(decomprbuf);
 148  out_readbuf:
 149         if(readbuf != buf)
 150                 kfree(readbuf);
 151  out_ri:
 152         jffs2_free_raw_inode(ri);
 153
 154         return ret;
 155 }
 156
 157 int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 158                            unsigned char *buf, uint32_t offset, uint32_t len)
 159 {
 160         uint32_t end = offset + len;
 161         struct jffs2_node_frag *frag;
 162         int ret;
 163
 164         jffs2_dbg(1, "%s(): ino #%u, range 0x%08x-0x%08x\n",
 165                   __func__, f->inocache->ino, offset, offset + len);
 166
 167         frag = jffs2_lookup_node_frag(&f->fragtree, offset);
 168
 169         /* XXX FIXME: Where a single physical node actually shows up in two
 170            frags, we read it twice. Don't do that. */
 171         /* Now we're pointing at the first frag which overlaps our page
 172          * (or perhaps is before it, if we've been asked to read off the
 173          * end of the file). */
 174         while(offset < end) {
 175                 jffs2_dbg(2, "%s(): offset %d, end %d\n",
 176                           __func__, offset, end);
 177                 if (unlikely(!frag || frag->ofs > offset ||
 178                              frag->ofs + frag->size <= offset)) {
 179                         uint32_t holesize = end - offset;
 180                         if (frag && frag->ofs > offset) {
 181                                 jffs2_dbg(1, "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n",
 182                                           f->inocache->ino, frag->ofs, offset);
 183                                 holesize = min(holesize, frag->ofs - offset);
 184                         }
 185                         jffs2_dbg(1, "Filling non-frag hole from %d-%d\n",
 186                                   offset, offset + holesize);
 187                         memset(buf, 0, holesize);
 188                         buf += holesize;
 189                         offset += holesize;
 190                         continue;
 191                 } else if (unlikely(!frag->node)) {
 192                         uint32_t holeend = min(end, frag->ofs + frag->size);
 193                         jffs2_dbg(1, "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n",
 194                                   offset, holeend, frag->ofs,
 195                                   frag->ofs + frag->size);
 196                         memset(buf, 0, holeend - offset);
 197                         buf += holeend - offset;
 198                         offset = holeend;
 199                         frag = frag_next(frag);
 200                         continue;
 201                 } else {
 202                         uint32_t readlen;
 203                         uint32_t fragofs; /* offset within the frag to start reading */
 204
 205                         fragofs = offset - frag->ofs;
 206                         readlen = min(frag->size - fragofs, end - offset);
 207                         jffs2_dbg(1, "Reading %d-%d from node at 0x%08x (%d)\n",
 208                                   frag->ofs+fragofs,
 209                                   frag->ofs + fragofs+readlen,
 210                                   ref_offset(frag->node->raw),
 211                                   ref_flags(frag->node->raw));
 212                         ret = jffs2_read_dnode(c, f, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);
 213                         jffs2_dbg(2, "node read done\n");
 214                         if (ret) {
 215                                 jffs2_dbg(1, "%s(): error %d\n",
 216                                           __func__, ret);
 217                                 memset(buf, 0, readlen);
 218                                 return ret;
 219                         }
 220                         buf += readlen;
 221                         offset += readlen;
 222                         frag = frag_next(frag);
 223                         jffs2_dbg(2, "node read was OK. Looping\n");
 224                 }
 225         }
 226         return 0;
 227 }
 228