fs/jffs2/read.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright (C) 2001-2003 Red Hat, Inc.
   5  *
   6  * Created by David Woodhouse <dwmw2@redhat.com>
   7  *
   8  * For licensing information, see the file 'LICENCE' in this directory.
   9  *
  10  * $Id: read.c,v 1.34 2003/10/04 08:33:06 dwmw2 Exp $
  11  *
  12  */
  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
  22 int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_full_dnode *fd, unsigned char *buf, int ofs, int len)
  23 {
  24         struct jffs2_raw_inode *ri;
  25         size_t readlen;
  26         uint32_t crc;
  27         unsigned char *decomprbuf = NULL;
  28         unsigned char *readbuf = NULL;
  29         int ret = 0;
  30
  31         ri = jffs2_alloc_raw_inode();
  32         if (!ri)
  33                 return -ENOMEM;
  34
  35         ret = jffs2_flash_read(c, ref_offset(fd->raw), sizeof(*ri), &readlen, (char *)ri);
  36         if (ret) {
  37                 jffs2_free_raw_inode(ri);
  38                 printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", ref_offset(fd->raw), ret);
  39                 return ret;
  40         }
  41         if (readlen != sizeof(*ri)) {
  42                 jffs2_free_raw_inode(ri);
  43                 printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%zx bytes, got 0x%zx\n",
  44                        ref_offset(fd->raw), sizeof(*ri), readlen);
  45                 return -EIO;
  46         }
  47         crc = crc32(0, ri, sizeof(*ri)-8);
  48
  49         D1(printk(KERN_DEBUG "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
  50                   ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
  51                   crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
  52                   je32_to_cpu(ri->offset), buf));
  53         if (crc != je32_to_cpu(ri->node_crc)) {
  54                 printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",
  55                        je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
  56                 ret = -EIO;
  57                 goto out_ri;
  58         }
  59         /* There was a bug where we wrote hole nodes out with csize/dsize
  60            swapped. Deal with it */
  61         if (ri->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(ri->dsize) &&
  62             je32_to_cpu(ri->csize)) {
  63                 ri->dsize = ri->csize;
  64                 ri->csize = cpu_to_je32(0);
  65         }
  66
  67         D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
  68                 printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
  69                        len, ofs, je32_to_cpu(ri->dsize));
  70                 ret = -EINVAL;
  71                 goto out_ri;
  72         });
  73
  74
  75         if (ri->compr == JFFS2_COMPR_ZERO) {
  76                 memset(buf, 0, len);
  77                 goto out_ri;
  78         }
  79
  80         /* Cases:
  81            Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
  82            Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
  83            Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
  84            Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
  85         */
  86         if (ri->compr == JFFS2_COMPR_NONE && len == je32_to_cpu(ri->dsize)) {
  87                 readbuf = buf;
  88         } else {
  89                 readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
  90                 if (!readbuf) {
  91                         ret = -ENOMEM;
  92                         goto out_ri;
  93                 }
  94         }
  95         if (ri->compr != JFFS2_COMPR_NONE) {
  96                 if (len < je32_to_cpu(ri->dsize)) {
  97                         decomprbuf = kmalloc(je32_to_cpu(ri->dsize), GFP_KERNEL);
  98                         if (!decomprbuf) {
  99                                 ret = -ENOMEM;
 100                                 goto out_readbuf;
 101                         }
 102                 } else {
 103                         decomprbuf = buf;
 104                 }
 105         } else {
 106                 decomprbuf = readbuf;
 107         }
 108
 109         D2(printk(KERN_DEBUG "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
 110                   readbuf));
 111         ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
 112                                je32_to_cpu(ri->csize), &readlen, readbuf);
 113
 114         if (!ret && readlen != je32_to_cpu(ri->csize))
 115                 ret = -EIO;
 116         if (ret)
 117                 goto out_decomprbuf;
 118
 119         crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
 120         if (crc != je32_to_cpu(ri->data_crc)) {
 121                 printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n",
 122                        je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
 123                 ret = -EIO;
 124                 goto out_decomprbuf;
 125         }
 126         D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
 127         if (ri->compr != JFFS2_COMPR_NONE) {
 128                 D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n",
 129                           je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize), decomprbuf));
 130                 ret = jffs2_decompress(ri->compr, readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
 131                 if (ret) {
 132                         printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
 133                         goto out_decomprbuf;
 134                 }
 135         }
 136
 137         if (len < je32_to_cpu(ri->dsize)) {
 138                 memcpy(buf, decomprbuf+ofs, len);
 139         }
 140  out_decomprbuf:
 141         if(decomprbuf != buf && decomprbuf != readbuf)
 142                 kfree(decomprbuf);
 143  out_readbuf:
 144         if(readbuf != buf)
 145                 kfree(readbuf);
 146  out_ri:
 147         jffs2_free_raw_inode(ri);
 148
 149         return ret;
 150 }
 151
 152 int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 153                            unsigned char *buf, uint32_t offset, uint32_t len)
 154 {
 155         uint32_t end = offset + len;
 156         struct jffs2_node_frag *frag;
 157         int ret;
 158
 159         D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",
 160                   f->inocache->ino, offset, offset+len));
 161
 162         frag = jffs2_lookup_node_frag(&f->fragtree, offset);
 163
 164         /* XXX FIXME: Where a single physical node actually shows up in two
 165            frags, we read it twice. Don't do that. */
 166         /* Now we're pointing at the first frag which overlaps our page */
 167         while(offset < end) {
 168                 D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end));
 169                 if (unlikely(!frag || frag->ofs > offset)) {
 170                         uint32_t holesize = end - offset;
 171                         if (frag) {
 172                                 D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset));
 173                                 holesize = min(holesize, frag->ofs - offset);
 174                                 D1(jffs2_print_frag_list(f));
 175                         }
 176                         D1(printk(KERN_DEBUG "Filling non-frag hole from %d-%d\n", offset, offset+holesize));
 177                         memset(buf, 0, holesize);
 178                         buf += holesize;
 179                         offset += holesize;
 180                         continue;
 181                 } else if (unlikely(!frag->node)) {
 182                         uint32_t holeend = min(end, frag->ofs + frag->size);
 183                         D1(printk(KERN_DEBUG "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n", offset, holeend, frag->ofs, frag->ofs + frag->size));
 184                         memset(buf, 0, holeend - offset);
 185                         buf += holeend - offset;
 186                         offset = holeend;
 187                         frag = frag_next(frag);
 188                         continue;
 189                 } else {
 190                         uint32_t readlen;
 191                         uint32_t fragofs; /* offset within the frag to start reading */
 192
 193                         fragofs = offset - frag->ofs;
 194                         readlen = min(frag->size - fragofs, end - offset);
 195                         D1(printk(KERN_DEBUG "Reading %d-%d from node at 0x%08x (%d)\n",
 196                                   frag->ofs+fragofs, frag->ofs+fragofs+readlen,
 197                                   ref_offset(frag->node->raw), ref_flags(frag->node->raw)));
 198                         ret = jffs2_read_dnode(c, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);
 199                         D2(printk(KERN_DEBUG "node read done\n"));
 200                         if (ret) {
 201                                 D1(printk(KERN_DEBUG"jffs2_read_inode_range error %d\n",ret));
 202                                 memset(buf, 0, readlen);
 203                                 return ret;
 204                         }
 205                         buf += readlen;
 206                         offset += readlen;
 207                         frag = frag_next(frag);
 208                         D2(printk(KERN_DEBUG "node read was OK. Looping\n"));
 209                 }
 210         }
 211         return 0;
 212 }
 213
 214 /* Core function to read symlink target. */
 215 char *jffs2_getlink(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
 216 {
 217         char *buf;
 218         int ret;
 219
 220         down(&f->sem);
 221
 222         if (!f->metadata) {
 223                 printk(KERN_NOTICE "No metadata for symlink inode #%u\n", f->inocache->ino);
 224                 up(&f->sem);
 225                 return ERR_PTR(-EINVAL);
 226         }
 227         buf = kmalloc(f->metadata->size+1, GFP_USER);
 228         if (!buf) {
 229                 up(&f->sem);
 230                 return ERR_PTR(-ENOMEM);
 231         }
 232         buf[f->metadata->size]=0;
 233
 234         ret = jffs2_read_dnode(c, f->metadata, buf, 0, f->metadata->size);
 235
 236         up(&f->sem);
 237
 238         if (ret) {
 239                 kfree(buf);
 240                 return ERR_PTR(ret);
 241         }
 242         return buf;
 243 }