fs/qnx6/dir.c

   1 /*
   2  * QNX6 file system, Linux implementation.
   3  *
   4  * Version : 1.0.0
   5  *
   6  * History :
   7  *
   8  * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
   9  * 16-02-2012 pagemap extension by Al Viro
  10  *
  11  */
  12
  13 #include "qnx6.h"
  14
  15 static unsigned qnx6_lfile_checksum(char *name, unsigned size)
  16 {
  17         unsigned crc = 0;
  18         char *end = name + size;
  19         while (name < end) {
  20                 crc = ((crc >> 1) + *(name++)) ^
  21                         ((crc & 0x00000001) ? 0x80000000 : 0);
  22         }
  23         return crc;
  24 }
  25
  26 static struct page *qnx6_get_page(struct inode *dir, unsigned long n)
  27 {
  28         struct address_space *mapping = dir->i_mapping;
  29         struct page *page = read_mapping_page(mapping, n, NULL);
  30         if (!IS_ERR(page))
  31                 kmap(page);
  32         return page;
  33 }
  34
  35 static inline unsigned long dir_pages(struct inode *inode)
  36 {
  37         return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
  38 }
  39
  40 static unsigned last_entry(struct inode *inode, unsigned long page_nr)
  41 {
  42         unsigned long last_byte = inode->i_size;
  43         last_byte -= page_nr << PAGE_CACHE_SHIFT;
  44         if (last_byte > PAGE_CACHE_SIZE)
  45                 last_byte = PAGE_CACHE_SIZE;
  46         return last_byte / QNX6_DIR_ENTRY_SIZE;
  47 }
  48
  49 static struct qnx6_long_filename *qnx6_longname(struct super_block *sb,
  50                                          struct qnx6_long_dir_entry *de,
  51                                          struct page **p)
  52 {
  53         struct qnx6_sb_info *sbi = QNX6_SB(sb);
  54         u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
  55         u32 n = s >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits); /* in pages */
  56         /* within page */
  57         u32 offs = (s << sb->s_blocksize_bits) & ~PAGE_CACHE_MASK;
  58         struct address_space *mapping = sbi->longfile->i_mapping;
  59         struct page *page = read_mapping_page(mapping, n, NULL);
  60         if (IS_ERR(page))
  61                 return ERR_CAST(page);
  62         kmap(*p = page);
  63         return (struct qnx6_long_filename *)(page_address(page) + offs);
  64 }
  65
  66 static int qnx6_dir_longfilename(struct inode *inode,
  67                         struct qnx6_long_dir_entry *de,
  68                         void *dirent, loff_t pos,
  69                         unsigned de_inode, filldir_t filldir)
  70 {
  71         struct qnx6_long_filename *lf;
  72         struct super_block *s = inode->i_sb;
  73         struct qnx6_sb_info *sbi = QNX6_SB(s);
  74         struct page *page;
  75         int lf_size;
  76
  77         if (de->de_size != 0xff) {
  78                 /* error - long filename entries always have size 0xff
  79                    in direntry */
  80                 printk(KERN_ERR "qnx6: invalid direntry size (%i).\n",
  81                                 de->de_size);
  82                 return 0;
  83         }
  84         lf = qnx6_longname(s, de, &page);
  85         if (IS_ERR(lf)) {
  86                 printk(KERN_ERR "qnx6:Error reading longname\n");
  87                 return 0;
  88         }
  89
  90         lf_size = fs16_to_cpu(sbi, lf->lf_size);
  91
  92         if (lf_size > QNX6_LONG_NAME_MAX) {
  93                 QNX6DEBUG((KERN_INFO "file %s\n", lf->lf_fname));
  94                 printk(KERN_ERR "qnx6:Filename too long (%i)\n", lf_size);
  95                 qnx6_put_page(page);
  96                 return 0;
  97         }
  98
  99         /* calc & validate longfilename checksum
 100            mmi 3g filesystem does not have that checksum */
 101         if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
 102                         qnx6_lfile_checksum(lf->lf_fname, lf_size))
 103                 printk(KERN_INFO "qnx6: long filename checksum error.\n");
 104
 105         QNX6DEBUG((KERN_INFO "qnx6_readdir:%.*s inode:%u\n",
 106                                         lf_size, lf->lf_fname, de_inode));
 107         if (filldir(dirent, lf->lf_fname, lf_size, pos, de_inode,
 108                         DT_UNKNOWN) < 0) {
 109                 qnx6_put_page(page);
 110                 return 0;
 111         }
 112
 113         qnx6_put_page(page);
 114         /* success */
 115         return 1;
 116 }
 117
 118 static int qnx6_readdir(struct file *filp, void *dirent, filldir_t filldir)
 119 {
 120         struct inode *inode = file_inode(filp);
 121         struct super_block *s = inode->i_sb;
 122         struct qnx6_sb_info *sbi = QNX6_SB(s);
 123         loff_t pos = filp->f_pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
 124         unsigned long npages = dir_pages(inode);
 125         unsigned long n = pos >> PAGE_CACHE_SHIFT;
 126         unsigned start = (pos & ~PAGE_CACHE_MASK) / QNX6_DIR_ENTRY_SIZE;
 127         bool done = false;
 128
 129         if (filp->f_pos >= inode->i_size)
 130                 return 0;
 131
 132         for ( ; !done && n < npages; n++, start = 0) {
 133                 struct page *page = qnx6_get_page(inode, n);
 134                 int limit = last_entry(inode, n);
 135                 struct qnx6_dir_entry *de;
 136                 int i = start;
 137
 138                 if (IS_ERR(page)) {
 139                         printk(KERN_ERR "qnx6_readdir: read failed\n");
 140                         filp->f_pos = (n + 1) << PAGE_CACHE_SHIFT;
 141                         return PTR_ERR(page);
 142                 }
 143                 de = ((struct qnx6_dir_entry *)page_address(page)) + start;
 144                 for (; i < limit; i++, de++, pos += QNX6_DIR_ENTRY_SIZE) {
 145                         int size = de->de_size;
 146                         u32 no_inode = fs32_to_cpu(sbi, de->de_inode);
 147
 148                         if (!no_inode || !size)
 149                                 continue;
 150
 151                         if (size > QNX6_SHORT_NAME_MAX) {
 152                                 /* long filename detected
 153                                    get the filename from long filename
 154                                    structure / block */
 155                                 if (!qnx6_dir_longfilename(inode,
 156                                         (struct qnx6_long_dir_entry *)de,
 157                                         dirent, pos, no_inode,
 158                                         filldir)) {
 159                                         done = true;
 160                                         break;
 161                                 }
 162                         } else {
 163                                 QNX6DEBUG((KERN_INFO "qnx6_readdir:%.*s"
 164                                    " inode:%u\n", size, de->de_fname,
 165                                                         no_inode));
 166                                 if (filldir(dirent, de->de_fname, size,
 167                                       pos, no_inode, DT_UNKNOWN)
 168                                         < 0) {
 169                                         done = true;
 170                                         break;
 171                                 }
 172                         }
 173                 }
 174                 qnx6_put_page(page);
 175         }
 176         filp->f_pos = pos;
 177         return 0;
 178 }
 179
 180 /*
 181  * check if the long filename is correct.
 182  */
 183 static unsigned qnx6_long_match(int len, const char *name,
 184                         struct qnx6_long_dir_entry *de, struct inode *dir)
 185 {
 186         struct super_block *s = dir->i_sb;
 187         struct qnx6_sb_info *sbi = QNX6_SB(s);
 188         struct page *page;
 189         int thislen;
 190         struct qnx6_long_filename *lf = qnx6_longname(s, de, &page);
 191
 192         if (IS_ERR(lf))
 193                 return 0;
 194
 195         thislen = fs16_to_cpu(sbi, lf->lf_size);
 196         if (len != thislen) {
 197                 qnx6_put_page(page);
 198                 return 0;
 199         }
 200         if (memcmp(name, lf->lf_fname, len) == 0) {
 201                 qnx6_put_page(page);
 202                 return fs32_to_cpu(sbi, de->de_inode);
 203         }
 204         qnx6_put_page(page);
 205         return 0;
 206 }
 207
 208 /*
 209  * check if the filename is correct.
 210  */
 211 static unsigned qnx6_match(struct super_block *s, int len, const char *name,
 212                         struct qnx6_dir_entry *de)
 213 {
 214         struct qnx6_sb_info *sbi = QNX6_SB(s);
 215         if (memcmp(name, de->de_fname, len) == 0)
 216                 return fs32_to_cpu(sbi, de->de_inode);
 217         return 0;
 218 }
 219
 220
 221 unsigned qnx6_find_entry(int len, struct inode *dir, const char *name,
 222                          struct page **res_page)
 223 {
 224         struct super_block *s = dir->i_sb;
 225         struct qnx6_inode_info *ei = QNX6_I(dir);
 226         struct page *page = NULL;
 227         unsigned long start, n;
 228         unsigned long npages = dir_pages(dir);
 229         unsigned ino;
 230         struct qnx6_dir_entry *de;
 231         struct qnx6_long_dir_entry *lde;
 232
 233         *res_page = NULL;
 234
 235         if (npages == 0)
 236                 return 0;
 237         start = ei->i_dir_start_lookup;
 238         if (start >= npages)
 239                 start = 0;
 240         n = start;
 241
 242         do {
 243                 page = qnx6_get_page(dir, n);
 244                 if (!IS_ERR(page)) {
 245                         int limit = last_entry(dir, n);
 246                         int i;
 247
 248                         de = (struct qnx6_dir_entry *)page_address(page);
 249                         for (i = 0; i < limit; i++, de++) {
 250                                 if (len <= QNX6_SHORT_NAME_MAX) {
 251                                         /* short filename */
 252                                         if (len != de->de_size)
 253                                                 continue;
 254                                         ino = qnx6_match(s, len, name, de);
 255                                         if (ino)
 256                                                 goto found;
 257                                 } else if (de->de_size == 0xff) {
 258                                         /* deal with long filename */
 259                                         lde = (struct qnx6_long_dir_entry *)de;
 260                                         ino = qnx6_long_match(len,
 261                                                                 name, lde, dir);
 262                                         if (ino)
 263                                                 goto found;
 264                                 } else
 265                                         printk(KERN_ERR "qnx6: undefined "
 266                                                 "filename size in inode.\n");
 267                         }
 268                         qnx6_put_page(page);
 269                 }
 270
 271                 if (++n >= npages)
 272                         n = 0;
 273         } while (n != start);
 274         return 0;
 275
 276 found:
 277         *res_page = page;
 278         ei->i_dir_start_lookup = n;
 279         return ino;
 280 }
 281
 282 const struct file_operations qnx6_dir_operations = {
 283         .llseek         = generic_file_llseek,
 284         .read           = generic_read_dir,
 285         .readdir        = qnx6_readdir,
 286         .fsync          = generic_file_fsync,
 287 };
 288
 289 const struct inode_operations qnx6_dir_inode_operations = {
 290         .lookup         = qnx6_lookup,
 291 };