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                         struct dir_context *ctx,
  69                         unsigned de_inode)
  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 (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
 108                 qnx6_put_page(page);
 109                 return 0;
 110         }
 111
 112         qnx6_put_page(page);
 113         /* success */
 114         return 1;
 115 }
 116
 117 static int qnx6_readdir(struct file *file, struct dir_context *ctx)
 118 {
 119         struct inode *inode = file_inode(file);
 120         struct super_block *s = inode->i_sb;
 121         struct qnx6_sb_info *sbi = QNX6_SB(s);
 122         loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
 123         unsigned long npages = dir_pages(inode);
 124         unsigned long n = pos >> PAGE_CACHE_SHIFT;
 125         unsigned start = (pos & ~PAGE_CACHE_MASK) / QNX6_DIR_ENTRY_SIZE;
 126         bool done = false;
 127
 128         ctx->pos = pos;
 129         if (ctx->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                         ctx->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++, ctx->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                                         ctx, no_inode)) {
 158                                         done = true;
 159                                         break;
 160                                 }
 161                         } else {
 162                                 QNX6DEBUG((KERN_INFO "qnx6_readdir:%.*s"
 163                                    " inode:%u\n", size, de->de_fname,
 164                                                         no_inode));
 165                                 if (!dir_emit(ctx, de->de_fname, size,
 166                                       no_inode, DT_UNKNOWN)) {
 167                                         done = true;
 168                                         break;
 169                                 }
 170                         }
 171                 }
 172                 qnx6_put_page(page);
 173         }
 174         return 0;
 175 }
 176
 177 /*
 178  * check if the long filename is correct.
 179  */
 180 static unsigned qnx6_long_match(int len, const char *name,
 181                         struct qnx6_long_dir_entry *de, struct inode *dir)
 182 {
 183         struct super_block *s = dir->i_sb;
 184         struct qnx6_sb_info *sbi = QNX6_SB(s);
 185         struct page *page;
 186         int thislen;
 187         struct qnx6_long_filename *lf = qnx6_longname(s, de, &page);
 188
 189         if (IS_ERR(lf))
 190                 return 0;
 191
 192         thislen = fs16_to_cpu(sbi, lf->lf_size);
 193         if (len != thislen) {
 194                 qnx6_put_page(page);
 195                 return 0;
 196         }
 197         if (memcmp(name, lf->lf_fname, len) == 0) {
 198                 qnx6_put_page(page);
 199                 return fs32_to_cpu(sbi, de->de_inode);
 200         }
 201         qnx6_put_page(page);
 202         return 0;
 203 }
 204
 205 /*
 206  * check if the filename is correct.
 207  */
 208 static unsigned qnx6_match(struct super_block *s, int len, const char *name,
 209                         struct qnx6_dir_entry *de)
 210 {
 211         struct qnx6_sb_info *sbi = QNX6_SB(s);
 212         if (memcmp(name, de->de_fname, len) == 0)
 213                 return fs32_to_cpu(sbi, de->de_inode);
 214         return 0;
 215 }
 216
 217
 218 unsigned qnx6_find_entry(int len, struct inode *dir, const char *name,
 219                          struct page **res_page)
 220 {
 221         struct super_block *s = dir->i_sb;
 222         struct qnx6_inode_info *ei = QNX6_I(dir);
 223         struct page *page = NULL;
 224         unsigned long start, n;
 225         unsigned long npages = dir_pages(dir);
 226         unsigned ino;
 227         struct qnx6_dir_entry *de;
 228         struct qnx6_long_dir_entry *lde;
 229
 230         *res_page = NULL;
 231
 232         if (npages == 0)
 233                 return 0;
 234         start = ei->i_dir_start_lookup;
 235         if (start >= npages)
 236                 start = 0;
 237         n = start;
 238
 239         do {
 240                 page = qnx6_get_page(dir, n);
 241                 if (!IS_ERR(page)) {
 242                         int limit = last_entry(dir, n);
 243                         int i;
 244
 245                         de = (struct qnx6_dir_entry *)page_address(page);
 246                         for (i = 0; i < limit; i++, de++) {
 247                                 if (len <= QNX6_SHORT_NAME_MAX) {
 248                                         /* short filename */
 249                                         if (len != de->de_size)
 250                                                 continue;
 251                                         ino = qnx6_match(s, len, name, de);
 252                                         if (ino)
 253                                                 goto found;
 254                                 } else if (de->de_size == 0xff) {
 255                                         /* deal with long filename */
 256                                         lde = (struct qnx6_long_dir_entry *)de;
 257                                         ino = qnx6_long_match(len,
 258                                                                 name, lde, dir);
 259                                         if (ino)
 260                                                 goto found;
 261                                 } else
 262                                         printk(KERN_ERR "qnx6: undefined "
 263                                                 "filename size in inode.\n");
 264                         }
 265                         qnx6_put_page(page);
 266                 }
 267
 268                 if (++n >= npages)
 269                         n = 0;
 270         } while (n != start);
 271         return 0;
 272
 273 found:
 274         *res_page = page;
 275         ei->i_dir_start_lookup = n;
 276         return ino;
 277 }
 278
 279 const struct file_operations qnx6_dir_operations = {
 280         .llseek         = generic_file_llseek,
 281         .read           = generic_read_dir,
 282         .iterate        = qnx6_readdir,
 283         .fsync          = generic_file_fsync,
 284 };
 285
 286 const struct inode_operations qnx6_dir_inode_operations = {
 287         .lookup         = qnx6_lookup,
 288 };