1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * QNX6 file system, Linux implementation. 4 * 5 * Version : 1.0.0 6 * 7 * History : 8 * 9 * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release. 10 * 16-02-2012 pagemap extension by Al Viro 11 * 12 */ 13 14 #include "qnx6.h" 15 16 static unsigned qnx6_lfile_checksum(char *name, unsigned size) 17 { 18 unsigned crc = 0; 19 char *end = name + size; 20 while (name < end) { 21 crc = ((crc >> 1) + *(name++)) ^ 22 ((crc & 0x00000001) ? 0x80000000 : 0); 23 } 24 return crc; 25 } 26 27 static struct page *qnx6_get_page(struct inode *dir, unsigned long n) 28 { 29 struct address_space *mapping = dir->i_mapping; 30 struct page *page = read_mapping_page(mapping, n, NULL); 31 if (!IS_ERR(page)) 32 kmap(page); 33 return page; 34 } 35 36 static unsigned last_entry(struct inode *inode, unsigned long page_nr) 37 { 38 unsigned long last_byte = inode->i_size; 39 last_byte -= page_nr << PAGE_SHIFT; 40 if (last_byte > PAGE_SIZE) 41 last_byte = PAGE_SIZE; 42 return last_byte / QNX6_DIR_ENTRY_SIZE; 43 } 44 45 static struct qnx6_long_filename *qnx6_longname(struct super_block *sb, 46 struct qnx6_long_dir_entry *de, 47 struct page **p) 48 { 49 struct qnx6_sb_info *sbi = QNX6_SB(sb); 50 u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */ 51 u32 n = s >> (PAGE_SHIFT - sb->s_blocksize_bits); /* in pages */ 52 /* within page */ 53 u32 offs = (s << sb->s_blocksize_bits) & ~PAGE_MASK; 54 struct address_space *mapping = sbi->longfile->i_mapping; 55 struct page *page = read_mapping_page(mapping, n, NULL); 56 if (IS_ERR(page)) 57 return ERR_CAST(page); 58 kmap(*p = page); 59 return (struct qnx6_long_filename *)(page_address(page) + offs); 60 } 61 62 static int qnx6_dir_longfilename(struct inode *inode, 63 struct qnx6_long_dir_entry *de, 64 struct dir_context *ctx, 65 unsigned de_inode) 66 { 67 struct qnx6_long_filename *lf; 68 struct super_block *s = inode->i_sb; 69 struct qnx6_sb_info *sbi = QNX6_SB(s); 70 struct page *page; 71 int lf_size; 72 73 if (de->de_size != 0xff) { 74 /* error - long filename entries always have size 0xff 75 in direntry */ 76 pr_err("invalid direntry size (%i).\n", de->de_size); 77 return 0; 78 } 79 lf = qnx6_longname(s, de, &page); 80 if (IS_ERR(lf)) { 81 pr_err("Error reading longname\n"); 82 return 0; 83 } 84 85 lf_size = fs16_to_cpu(sbi, lf->lf_size); 86 87 if (lf_size > QNX6_LONG_NAME_MAX) { 88 pr_debug("file %s\n", lf->lf_fname); 89 pr_err("Filename too long (%i)\n", lf_size); 90 qnx6_put_page(page); 91 return 0; 92 } 93 94 /* calc & validate longfilename checksum 95 mmi 3g filesystem does not have that checksum */ 96 if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) != 97 qnx6_lfile_checksum(lf->lf_fname, lf_size)) 98 pr_info("long filename checksum error.\n"); 99 100 pr_debug("qnx6_readdir:%.*s inode:%u\n", 101 lf_size, lf->lf_fname, de_inode); 102 if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) { 103 qnx6_put_page(page); 104 return 0; 105 } 106 107 qnx6_put_page(page); 108 /* success */ 109 return 1; 110 } 111 112 static int qnx6_readdir(struct file *file, struct dir_context *ctx) 113 { 114 struct inode *inode = file_inode(file); 115 struct super_block *s = inode->i_sb; 116 struct qnx6_sb_info *sbi = QNX6_SB(s); 117 loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1); 118 unsigned long npages = dir_pages(inode); 119 unsigned long n = pos >> PAGE_SHIFT; 120 unsigned start = (pos & ~PAGE_MASK) / QNX6_DIR_ENTRY_SIZE; 121 bool done = false; 122 123 ctx->pos = pos; 124 if (ctx->pos >= inode->i_size) 125 return 0; 126 127 for ( ; !done && n < npages; n++, start = 0) { 128 struct page *page = qnx6_get_page(inode, n); 129 int limit = last_entry(inode, n); 130 struct qnx6_dir_entry *de; 131 int i = start; 132 133 if (IS_ERR(page)) { 134 pr_err("%s(): read failed\n", __func__); 135 ctx->pos = (n + 1) << PAGE_SHIFT; 136 return PTR_ERR(page); 137 } 138 de = ((struct qnx6_dir_entry *)page_address(page)) + start; 139 for (; i < limit; i++, de++, ctx->pos += QNX6_DIR_ENTRY_SIZE) { 140 int size = de->de_size; 141 u32 no_inode = fs32_to_cpu(sbi, de->de_inode); 142 143 if (!no_inode || !size) 144 continue; 145 146 if (size > QNX6_SHORT_NAME_MAX) { 147 /* long filename detected 148 get the filename from long filename 149 structure / block */ 150 if (!qnx6_dir_longfilename(inode, 151 (struct qnx6_long_dir_entry *)de, 152 ctx, no_inode)) { 153 done = true; 154 break; 155 } 156 } else { 157 pr_debug("%s():%.*s inode:%u\n", 158 __func__, size, de->de_fname, 159 no_inode); 160 if (!dir_emit(ctx, de->de_fname, size, 161 no_inode, DT_UNKNOWN)) { 162 done = true; 163 break; 164 } 165 } 166 } 167 qnx6_put_page(page); 168 } 169 return 0; 170 } 171 172 /* 173 * check if the long filename is correct. 174 */ 175 static unsigned qnx6_long_match(int len, const char *name, 176 struct qnx6_long_dir_entry *de, struct inode *dir) 177 { 178 struct super_block *s = dir->i_sb; 179 struct qnx6_sb_info *sbi = QNX6_SB(s); 180 struct page *page; 181 int thislen; 182 struct qnx6_long_filename *lf = qnx6_longname(s, de, &page); 183 184 if (IS_ERR(lf)) 185 return 0; 186 187 thislen = fs16_to_cpu(sbi, lf->lf_size); 188 if (len != thislen) { 189 qnx6_put_page(page); 190 return 0; 191 } 192 if (memcmp(name, lf->lf_fname, len) == 0) { 193 qnx6_put_page(page); 194 return fs32_to_cpu(sbi, de->de_inode); 195 } 196 qnx6_put_page(page); 197 return 0; 198 } 199 200 /* 201 * check if the filename is correct. 202 */ 203 static unsigned qnx6_match(struct super_block *s, int len, const char *name, 204 struct qnx6_dir_entry *de) 205 { 206 struct qnx6_sb_info *sbi = QNX6_SB(s); 207 if (memcmp(name, de->de_fname, len) == 0) 208 return fs32_to_cpu(sbi, de->de_inode); 209 return 0; 210 } 211 212 213 unsigned qnx6_find_entry(int len, struct inode *dir, const char *name, 214 struct page **res_page) 215 { 216 struct super_block *s = dir->i_sb; 217 struct qnx6_inode_info *ei = QNX6_I(dir); 218 struct page *page = NULL; 219 unsigned long start, n; 220 unsigned long npages = dir_pages(dir); 221 unsigned ino; 222 struct qnx6_dir_entry *de; 223 struct qnx6_long_dir_entry *lde; 224 225 *res_page = NULL; 226 227 if (npages == 0) 228 return 0; 229 start = ei->i_dir_start_lookup; 230 if (start >= npages) 231 start = 0; 232 n = start; 233 234 do { 235 page = qnx6_get_page(dir, n); 236 if (!IS_ERR(page)) { 237 int limit = last_entry(dir, n); 238 int i; 239 240 de = (struct qnx6_dir_entry *)page_address(page); 241 for (i = 0; i < limit; i++, de++) { 242 if (len <= QNX6_SHORT_NAME_MAX) { 243 /* short filename */ 244 if (len != de->de_size) 245 continue; 246 ino = qnx6_match(s, len, name, de); 247 if (ino) 248 goto found; 249 } else if (de->de_size == 0xff) { 250 /* deal with long filename */ 251 lde = (struct qnx6_long_dir_entry *)de; 252 ino = qnx6_long_match(len, 253 name, lde, dir); 254 if (ino) 255 goto found; 256 } else 257 pr_err("undefined filename size in inode.\n"); 258 } 259 qnx6_put_page(page); 260 } 261 262 if (++n >= npages) 263 n = 0; 264 } while (n != start); 265 return 0; 266 267 found: 268 *res_page = page; 269 ei->i_dir_start_lookup = n; 270 return ino; 271 } 272 273 const struct file_operations qnx6_dir_operations = { 274 .llseek = generic_file_llseek, 275 .read = generic_read_dir, 276 .iterate_shared = qnx6_readdir, 277 .fsync = generic_file_fsync, 278 }; 279 280 const struct inode_operations qnx6_dir_inode_operations = { 281 .lookup = qnx6_lookup, 282 }; 283