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 
jffs2_read_dnode(struct jffs2_sb_info * c,struct jffs2_inode_info * f,struct jffs2_full_dnode * fd,unsigned char * buf,int ofs,int len)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 
jffs2_read_inode_range(struct jffs2_sb_info * c,struct jffs2_inode_info * f,unsigned char * buf,uint32_t offset,uint32_t len)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