Root/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#include <linux/kernel.h>
13#include <linux/slab.h>
14#include <linux/crc32.h>
15#include <linux/pagemap.h>
16#include <linux/mtd/mtd.h>
17#include <linux/compiler.h>
18#include "nodelist.h"
19#include "compr.h"
20
21int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
22             struct jffs2_full_dnode *fd, unsigned char *buf,
23             int ofs, int len)
24{
25    struct jffs2_raw_inode *ri;
26    size_t readlen;
27    uint32_t crc;
28    unsigned char *decomprbuf = NULL;
29    unsigned char *readbuf = NULL;
30    int ret = 0;
31
32    ri = jffs2_alloc_raw_inode();
33    if (!ri)
34        return -ENOMEM;
35
36    ret = jffs2_flash_read(c, ref_offset(fd->raw), sizeof(*ri), &readlen, (char *)ri);
37    if (ret) {
38        jffs2_free_raw_inode(ri);
39        printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", ref_offset(fd->raw), ret);
40        return ret;
41    }
42    if (readlen != sizeof(*ri)) {
43        jffs2_free_raw_inode(ri);
44        printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%zx bytes, got 0x%zx\n",
45               ref_offset(fd->raw), sizeof(*ri), readlen);
46        return -EIO;
47    }
48    crc = crc32(0, ri, sizeof(*ri)-8);
49
50    D1(printk(KERN_DEBUG "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
51          ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
52          crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
53          je32_to_cpu(ri->offset), buf));
54    if (crc != je32_to_cpu(ri->node_crc)) {
55        printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",
56               je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
57        ret = -EIO;
58        goto out_ri;
59    }
60    /* There was a bug where we wrote hole nodes out with csize/dsize
61       swapped. Deal with it */
62    if (ri->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(ri->dsize) &&
63        je32_to_cpu(ri->csize)) {
64        ri->dsize = ri->csize;
65        ri->csize = cpu_to_je32(0);
66    }
67
68    D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
69        printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
70               len, ofs, je32_to_cpu(ri->dsize));
71        ret = -EINVAL;
72        goto out_ri;
73    });
74
75
76    if (ri->compr == JFFS2_COMPR_ZERO) {
77        memset(buf, 0, len);
78        goto out_ri;
79    }
80
81    /* Cases:
82       Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
83       Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
84       Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
85       Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
86    */
87    if (ri->compr == JFFS2_COMPR_NONE && len == je32_to_cpu(ri->dsize)) {
88        readbuf = buf;
89    } else {
90        readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
91        if (!readbuf) {
92            ret = -ENOMEM;
93            goto out_ri;
94        }
95    }
96    if (ri->compr != JFFS2_COMPR_NONE) {
97        if (len < je32_to_cpu(ri->dsize)) {
98            decomprbuf = kmalloc(je32_to_cpu(ri->dsize), GFP_KERNEL);
99            if (!decomprbuf) {
100                ret = -ENOMEM;
101                goto out_readbuf;
102            }
103        } else {
104            decomprbuf = buf;
105        }
106    } else {
107        decomprbuf = readbuf;
108    }
109
110    D2(printk(KERN_DEBUG "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
111          readbuf));
112    ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
113                   je32_to_cpu(ri->csize), &readlen, readbuf);
114
115    if (!ret && readlen != je32_to_cpu(ri->csize))
116        ret = -EIO;
117    if (ret)
118        goto out_decomprbuf;
119
120    crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
121    if (crc != je32_to_cpu(ri->data_crc)) {
122        printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n",
123               je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
124        ret = -EIO;
125        goto out_decomprbuf;
126    }
127    D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
128    if (ri->compr != JFFS2_COMPR_NONE) {
129        D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n",
130              je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize), decomprbuf));
131        ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
132        if (ret) {
133            printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
134            goto out_decomprbuf;
135        }
136    }
137
138    if (len < je32_to_cpu(ri->dsize)) {
139        memcpy(buf, decomprbuf+ofs, len);
140    }
141 out_decomprbuf:
142    if(decomprbuf != buf && decomprbuf != readbuf)
143        kfree(decomprbuf);
144 out_readbuf:
145    if(readbuf != buf)
146        kfree(readbuf);
147 out_ri:
148    jffs2_free_raw_inode(ri);
149
150    return ret;
151}
152
153int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
154               unsigned char *buf, uint32_t offset, uint32_t len)
155{
156    uint32_t end = offset + len;
157    struct jffs2_node_frag *frag;
158    int ret;
159
160    D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",
161          f->inocache->ino, offset, offset+len));
162
163    frag = jffs2_lookup_node_frag(&f->fragtree, offset);
164
165    /* XXX FIXME: Where a single physical node actually shows up in two
166       frags, we read it twice. Don't do that. */
167    /* Now we're pointing at the first frag which overlaps our page */
168    while(offset < end) {
169        D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end));
170        if (unlikely(!frag || frag->ofs > offset)) {
171            uint32_t holesize = end - offset;
172            if (frag) {
173                D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset));
174                holesize = min(holesize, frag->ofs - offset);
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, f, 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

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