read.c (6891B)
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 23int 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 157int 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