fs/jffs2.org/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 1.36 2004/05/25 11:12:32 havasi 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 #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                 printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", ref_offset(fd->raw), ret);
  42                 return ret;
  43         }
  44         if (readlen != sizeof(*ri)) {
  45                 jffs2_free_raw_inode(ri);
  46                 printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%zx bytes, got 0x%zx\n",
  47                        ref_offset(fd->raw), sizeof(*ri), readlen);
  48                 return -EIO;
  49         }
  50         crc = crc32(0, ri, sizeof(*ri)-8);
  51
  52 #if 0   // mask by Victor Yu. 04-07-2007
  53         D1(printk(KERN_DEBUG "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 #endif
  58         if (crc != je32_to_cpu(ri->node_crc)) {
  59 #if 0   // mask by Victor Yu. 04-07-2007
  60                 printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",
  61                        je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
  62 #endif
  63                 ret = -EIO;
  64                 goto out_ri;
  65         }
  66         /* There was a bug where we wrote hole nodes out with csize/dsize
  67            swapped. Deal with it */
  68         if (ri->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(ri->dsize) &&
  69             je32_to_cpu(ri->csize)) {
  70                 ri->dsize = ri->csize;
  71                 ri->csize = cpu_to_je32(0);
  72         }
  73
  74         D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
  75                 printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
  76                        len, ofs, je32_to_cpu(ri->dsize));
  77                 ret = -EINVAL;
  78                 goto out_ri;
  79         });
  80
  81
  82         if (ri->compr == JFFS2_COMPR_ZERO) {
  83                 memset(buf, 0, len);
  84                 goto out_ri;
  85         }
  86
  87         /* Cases:
  88            Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
  89            Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
  90            Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
  91            Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
  92         */
  93         if (ri->compr == JFFS2_COMPR_NONE && len == je32_to_cpu(ri->dsize)) {
  94                 readbuf = buf;
  95         } else {
  96                 readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
  97                 if (!readbuf) {
  98                         ret = -ENOMEM;
  99                         goto out_ri;
 100                 }
 101         }
 102         if (ri->compr != JFFS2_COMPR_NONE) {
 103                 if (len < je32_to_cpu(ri->dsize)) {
 104                         decomprbuf = kmalloc(je32_to_cpu(ri->dsize), GFP_KERNEL);
 105                         if (!decomprbuf) {
 106                                 ret = -ENOMEM;
 107                                 goto out_readbuf;
 108                         }
 109                 } else {
 110                         decomprbuf = buf;
 111                 }
 112         } else {
 113                 decomprbuf = readbuf;
 114         }
 115
 116         D2(printk(KERN_DEBUG "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
 117                   readbuf));
 118         ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
 119                                je32_to_cpu(ri->csize), &readlen, readbuf);
 120
 121         if (!ret && readlen != je32_to_cpu(ri->csize))
 122                 ret = -EIO;
 123         if (ret)
 124                 goto out_decomprbuf;
 125
 126         crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
 127         if (crc != je32_to_cpu(ri->data_crc)) {
 128 #if 0   // mask by Victor Yu. 04-07-2007
 129                 printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n",
 130                        je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
 131 #endif
 132                 ret = -EIO;
 133                 goto out_decomprbuf;
 134         }
 135 #if 0   // mask by Victor Yu. 04-07-2007
 136         D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
 137 #endif
 138         if (ri->compr != JFFS2_COMPR_NONE) {
 139                 D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n",
 140                           je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize), decomprbuf));
 141                 ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
 142                 if (ret) {
 143                         printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
 144                         goto out_decomprbuf;
 145                 }
 146         }
 147
 148         if (len < je32_to_cpu(ri->dsize)) {
 149                 memcpy(buf, decomprbuf+ofs, len);
 150         }
 151  out_decomprbuf:
 152         if(decomprbuf != buf && decomprbuf != readbuf)
 153                 kfree(decomprbuf);
 154  out_readbuf:
 155         if(readbuf != buf)
 156                 kfree(readbuf);
 157  out_ri:
 158         jffs2_free_raw_inode(ri);
 159
 160         return ret;
 161 }
 162
 163 int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 164                            unsigned char *buf, uint32_t offset, uint32_t len)
 165 {
 166         uint32_t end = offset + len;
 167         struct jffs2_node_frag *frag;
 168         int ret;
 169
 170         D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",
 171                   f->inocache->ino, offset, offset+len));
 172
 173         frag = jffs2_lookup_node_frag(&f->fragtree, offset);
 174
 175         /* XXX FIXME: Where a single physical node actually shows up in two
 176            frags, we read it twice. Don't do that. */
 177         /* Now we're pointing at the first frag which overlaps our page */
 178         while(offset < end) {
 179                 D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end));
 180                 if (unlikely(!frag || frag->ofs > offset)) {
 181                         uint32_t holesize = end - offset;
 182                         if (frag) {
 183                                 D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset));
 184                                 holesize = min(holesize, frag->ofs - offset);
 185                                 D1(jffs2_print_frag_list(f));
 186                         }
 187                         D1(printk(KERN_DEBUG "Filling non-frag hole from %d-%d\n", offset, offset+holesize));
 188                         memset(buf, 0, holesize);
 189                         buf += holesize;
 190                         offset += holesize;
 191                         continue;
 192                 } else if (unlikely(!frag->node)) {
 193                         uint32_t holeend = min(end, frag->ofs + frag->size);
 194                         D1(printk(KERN_DEBUG "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n", offset, holeend, frag->ofs, frag->ofs + frag->size));
 195                         memset(buf, 0, holeend - offset);
 196                         buf += holeend - offset;
 197                         offset = holeend;
 198                         frag = frag_next(frag);
 199                         continue;
 200                 } else {
 201                         uint32_t readlen;
 202                         uint32_t fragofs; /* offset within the frag to start reading */
 203
 204                         fragofs = offset - frag->ofs;
 205                         readlen = min(frag->size - fragofs, end - offset);
 206                         D1(printk(KERN_DEBUG "Reading %d-%d from node at 0x%08x (%d)\n",
 207                                   frag->ofs+fragofs, frag->ofs+fragofs+readlen,
 208                                   ref_offset(frag->node->raw), ref_flags(frag->node->raw)));
 209                         ret = jffs2_read_dnode(c, f, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);
 210                         D2(printk(KERN_DEBUG "node read done\n"));
 211                         if (ret) {
 212                                 D1(printk(KERN_DEBUG"jffs2_read_inode_range error %d\n",ret));
 213                                 memset(buf, 0, readlen);
 214                                 return ret;
 215                         }
 216                         buf += readlen;
 217                         offset += readlen;
 218                         frag = frag_next(frag);
 219                         D2(printk(KERN_DEBUG "node read was OK. Looping\n"));
 220                 }
 221         }
 222         return 0;
 223 }
 224
 225 /* Core function to read symlink target. */
 226 char *jffs2_getlink(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
 227 {
 228         char *buf;
 229         int ret;
 230
 231         down(&f->sem);
 232
 233         if (!f->metadata) {
 234                 printk(KERN_NOTICE "No metadata for symlink inode #%u\n", f->inocache->ino);
 235                 up(&f->sem);
 236                 return ERR_PTR(-EINVAL);
 237         }
 238         buf = kmalloc(f->metadata->size+1, GFP_USER);
 239         if (!buf) {
 240                 up(&f->sem);
 241                 return ERR_PTR(-ENOMEM);
 242         }
 243         buf[f->metadata->size]=0;
 244
 245         ret = jffs2_read_dnode(c, f, f->metadata, buf, 0, f->metadata->size);
 246
 247         up(&f->sem);
 248
 249         if (ret) {
 250                 kfree(buf);
 251                 return ERR_PTR(ret);
 252         }
 253         return buf;
 254 }