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