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Linux/fs/jffs2/read.c

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  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 
229 

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