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@infradead.org>
7 *
8 * For licensing information, see the file 'LICENCE' in this directory.
9 *
10 * $Id: read.c,v 1.38 2004/11/16 20:36:12 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 #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 D1(printk(KERN_DEBUG "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
53 ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
54 crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
55 je32_to_cpu(ri->offset), buf));
56 if (crc != je32_to_cpu(ri->node_crc)) {
57 printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",
58 je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
59 ret = -EIO;
60 goto out_ri;
61 }
62 /* There was a bug where we wrote hole nodes out with csize/dsize
63 swapped. Deal with it */
64 if (ri->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(ri->dsize) &&
65 je32_to_cpu(ri->csize)) {
66 ri->dsize = ri->csize;
67 ri->csize = cpu_to_je32(0);
68 }
69
70 D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
71 printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
72 len, ofs, je32_to_cpu(ri->dsize));
73 ret = -EINVAL;
74 goto out_ri;
75 });
76
77
78 if (ri->compr == JFFS2_COMPR_ZERO) {
79 memset(buf, 0, len);
80 goto out_ri;
81 }
82
83 /* Cases:
84 Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
85 Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
86 Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
87 Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
88 */
89 if (ri->compr == JFFS2_COMPR_NONE && len == je32_to_cpu(ri->dsize)) {
90 readbuf = buf;
91 } else {
92 readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
93 if (!readbuf) {
94 ret = -ENOMEM;
95 goto out_ri;
96 }
97 }
98 if (ri->compr != JFFS2_COMPR_NONE) {
99 if (len < je32_to_cpu(ri->dsize)) {
100 decomprbuf = kmalloc(je32_to_cpu(ri->dsize), GFP_KERNEL);
101 if (!decomprbuf) {
102 ret = -ENOMEM;
103 goto out_readbuf;
104 }
105 } else {
106 decomprbuf = buf;
107 }
108 } else {
109 decomprbuf = readbuf;
110 }
111
112 D2(printk(KERN_DEBUG "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
113 readbuf));
114 ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
115 je32_to_cpu(ri->csize), &readlen, readbuf);
116
117 if (!ret && readlen != je32_to_cpu(ri->csize))
118 ret = -EIO;
119 if (ret)
120 goto out_decomprbuf;
121
122 crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
123 if (crc != je32_to_cpu(ri->data_crc)) {
124 printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n",
125 je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
126 ret = -EIO;
127 goto out_decomprbuf;
128 }
129 D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
130 if (ri->compr != JFFS2_COMPR_NONE) {
131 D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n",
132 je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize), decomprbuf));
133 ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
134 if (ret) {
135 printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
136 goto out_decomprbuf;
137 }
138 }
139
140 if (len < je32_to_cpu(ri->dsize)) {
141 memcpy(buf, decomprbuf+ofs, len);
142 }
143 out_decomprbuf:
144 if(decomprbuf != buf && decomprbuf != readbuf)
145 kfree(decomprbuf);
146 out_readbuf:
147 if(readbuf != buf)
148 kfree(readbuf);
149 out_ri:
150 jffs2_free_raw_inode(ri);
151
152 return ret;
153 }
154
155 int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
156 unsigned char *buf, uint32_t offset, uint32_t len)
157 {
158 uint32_t end = offset + len;
159 struct jffs2_node_frag *frag;
160 int ret;
161
162 D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",
163 f->inocache->ino, offset, offset+len));
164
165 frag = jffs2_lookup_node_frag(&f->fragtree, offset);
166
167 /* XXX FIXME: Where a single physical node actually shows up in two
168 frags, we read it twice. Don't do that. */
169 /* Now we're pointing at the first frag which overlaps our page */
170 while(offset < end) {
171 D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end));
172 if (unlikely(!frag || frag->ofs > offset)) {
173 uint32_t holesize = end - offset;
174 if (frag) {
175 D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset));
176 holesize = min(holesize, frag->ofs - offset);
177 D2(jffs2_print_frag_list(f));
178 }
179 D1(printk(KERN_DEBUG "Filling non-frag hole from %d-%d\n", offset, offset+holesize));
180 memset(buf, 0, holesize);
181 buf += holesize;
182 offset += holesize;
183 continue;
184 } else if (unlikely(!frag->node)) {
185 uint32_t holeend = min(end, frag->ofs + frag->size);
186 D1(printk(KERN_DEBUG "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n", offset, holeend, frag->ofs, frag->ofs + frag->size));
187 memset(buf, 0, holeend - offset);
188 buf += holeend - offset;
189 offset = holeend;
190 frag = frag_next(frag);
191 continue;
192 } else {
193 uint32_t readlen;
194 uint32_t fragofs; /* offset within the frag to start reading */
195
196 fragofs = offset - frag->ofs;
197 readlen = min(frag->size - fragofs, end - offset);
198 D1(printk(KERN_DEBUG "Reading %d-%d from node at 0x%08x (%d)\n",
199 frag->ofs+fragofs, frag->ofs+fragofs+readlen,
200 ref_offset(frag->node->raw), ref_flags(frag->node->raw)));
201 ret = jffs2_read_dnode(c, f, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);
202 D2(printk(KERN_DEBUG "node read done\n"));
203 if (ret) {
204 D1(printk(KERN_DEBUG"jffs2_read_inode_range error %d\n",ret));
205 memset(buf, 0, readlen);
206 return ret;
207 }
208 buf += readlen;
209 offset += readlen;
210 frag = frag_next(frag);
211 D2(printk(KERN_DEBUG "node read was OK. Looping\n"));
212 }
213 }
214 return 0;
215 }
216
217 /* Core function to read symlink target. */
218 char *jffs2_getlink(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
219 {
220 char *buf;
221 int ret;
222
223 down(&f->sem);
224
225 if (!f->metadata) {
226 printk(KERN_NOTICE "No metadata for symlink inode #%u\n", f->inocache->ino);
227 up(&f->sem);
228 return ERR_PTR(-EINVAL);
229 }
230 buf = kmalloc(f->metadata->size+1, GFP_USER);
231 if (!buf) {
232 up(&f->sem);
233 return ERR_PTR(-ENOMEM);
234 }
235 buf[f->metadata->size]=0;
236
237 ret = jffs2_read_dnode(c, f, f->metadata, buf, 0, f->metadata->size);
238
239 up(&f->sem);
240
241 if (ret) {
242 kfree(buf);
243 return ERR_PTR(ret);
244 }
245 return buf;
246 }
247
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