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 ([email protected]) : 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                 pr_err("invalid direntry size (%i).\n", de->de_size);
  81                 return 0;
  82         }
  83         lf = qnx6_longname(s, de, &page);
  84         if (IS_ERR(lf)) {
  85                 pr_err("Error reading longname\n");
  86                 return 0;
  87         }
  88
  89         lf_size = fs16_to_cpu(sbi, lf->lf_size);
  90
  91         if (lf_size > QNX6_LONG_NAME_MAX) {
  92                 pr_debug("file %s\n", lf->lf_fname);
  93                 pr_err("Filename too long (%i)\n", lf_size);
  94                 qnx6_put_page(page);
  95                 return 0;
  96         }
  97
  98         /* calc & validate longfilename checksum
  99            mmi 3g filesystem does not have that checksum */
 100         if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
 101                         qnx6_lfile_checksum(lf->lf_fname, lf_size))
 102                 pr_info("long filename checksum error.\n");
 103
 104         pr_debug("qnx6_readdir:%.*s inode:%u\n",
 105                  lf_size, lf->lf_fname, de_inode);
 106         if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
 107                 qnx6_put_page(page);
 108                 return 0;
 109         }
 110
 111         qnx6_put_page(page);
 112         /* success */
 113         return 1;
 114 }
 115
 116 static int qnx6_readdir(struct file *file, struct dir_context *ctx)
 117 {
 118         struct inode *inode = file_inode(file);
 119         struct super_block *s = inode->i_sb;
 120         struct qnx6_sb_info *sbi = QNX6_SB(s);
 121         loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
 122         unsigned long npages = dir_pages(inode);
 123         unsigned long n = pos >> PAGE_CACHE_SHIFT;
 124         unsigned start = (pos & ~PAGE_CACHE_MASK) / QNX6_DIR_ENTRY_SIZE;
 125         bool done = false;
 126
 127         ctx->pos = pos;
 128         if (ctx->pos >= inode->i_size)
 129                 return 0;
 130
 131         for ( ; !done && n < npages; n++, start = 0) {
 132                 struct page *page = qnx6_get_page(inode, n);
 133                 int limit = last_entry(inode, n);
 134                 struct qnx6_dir_entry *de;
 135                 int i = start;
 136
 137                 if (IS_ERR(page)) {
 138                         pr_err("%s(): read failed\n", __func__);
 139                         ctx->pos = (n + 1) << PAGE_CACHE_SHIFT;
 140                         return PTR_ERR(page);
 141                 }
 142                 de = ((struct qnx6_dir_entry *)page_address(page)) + start;
 143                 for (; i < limit; i++, de++, ctx->pos += QNX6_DIR_ENTRY_SIZE) {
 144                         int size = de->de_size;
 145                         u32 no_inode = fs32_to_cpu(sbi, de->de_inode);
 146
 147                         if (!no_inode || !size)
 148                                 continue;
 149
 150                         if (size > QNX6_SHORT_NAME_MAX) {
 151                                 /* long filename detected
 152                                    get the filename from long filename
 153                                    structure / block */
 154                                 if (!qnx6_dir_longfilename(inode,
 155                                         (struct qnx6_long_dir_entry *)de,
 156                                         ctx, no_inode)) {
 157                                         done = true;
 158                                         break;
 159                                 }
 160                         } else {
 161                                 pr_debug("%s():%.*s inode:%u\n",
 162                                          __func__, size, de->de_fname,
 163                                          no_inode);
 164                                 if (!dir_emit(ctx, de->de_fname, size,
 165                                       no_inode, DT_UNKNOWN)) {
 166                                         done = true;
 167                                         break;
 168                                 }
 169                         }
 170                 }
 171                 qnx6_put_page(page);
 172         }
 173         return 0;
 174 }
 175
 176 /*
 177  * check if the long filename is correct.
 178  */
 179 static unsigned qnx6_long_match(int len, const char *name,
 180                         struct qnx6_long_dir_entry *de, struct inode *dir)
 181 {
 182         struct super_block *s = dir->i_sb;
 183         struct qnx6_sb_info *sbi = QNX6_SB(s);
 184         struct page *page;
 185         int thislen;
 186         struct qnx6_long_filename *lf = qnx6_longname(s, de, &page);
 187
 188         if (IS_ERR(lf))
 189                 return 0;
 190
 191         thislen = fs16_to_cpu(sbi, lf->lf_size);
 192         if (len != thislen) {
 193                 qnx6_put_page(page);
 194                 return 0;
 195         }
 196         if (memcmp(name, lf->lf_fname, len) == 0) {
 197                 qnx6_put_page(page);
 198                 return fs32_to_cpu(sbi, de->de_inode);
 199         }
 200         qnx6_put_page(page);
 201         return 0;
 202 }
 203
 204 /*
 205  * check if the filename is correct.
 206  */
 207 static unsigned qnx6_match(struct super_block *s, int len, const char *name,
 208                         struct qnx6_dir_entry *de)
 209 {
 210         struct qnx6_sb_info *sbi = QNX6_SB(s);
 211         if (memcmp(name, de->de_fname, len) == 0)
 212                 return fs32_to_cpu(sbi, de->de_inode);
 213         return 0;
 214 }
 215
 216
 217 unsigned qnx6_find_entry(int len, struct inode *dir, const char *name,
 218                          struct page **res_page)
 219 {
 220         struct super_block *s = dir->i_sb;
 221         struct qnx6_inode_info *ei = QNX6_I(dir);
 222         struct page *page = NULL;
 223         unsigned long start, n;
 224         unsigned long npages = dir_pages(dir);
 225         unsigned ino;
 226         struct qnx6_dir_entry *de;
 227         struct qnx6_long_dir_entry *lde;
 228
 229         *res_page = NULL;
 230
 231         if (npages == 0)
 232                 return 0;
 233         start = ei->i_dir_start_lookup;
 234         if (start >= npages)
 235                 start = 0;
 236         n = start;
 237
 238         do {
 239                 page = qnx6_get_page(dir, n);
 240                 if (!IS_ERR(page)) {
 241                         int limit = last_entry(dir, n);
 242                         int i;
 243
 244                         de = (struct qnx6_dir_entry *)page_address(page);
 245                         for (i = 0; i < limit; i++, de++) {
 246                                 if (len <= QNX6_SHORT_NAME_MAX) {
 247                                         /* short filename */
 248                                         if (len != de->de_size)
 249                                                 continue;
 250                                         ino = qnx6_match(s, len, name, de);
 251                                         if (ino)
 252                                                 goto found;
 253                                 } else if (de->de_size == 0xff) {
 254                                         /* deal with long filename */
 255                                         lde = (struct qnx6_long_dir_entry *)de;
 256                                         ino = qnx6_long_match(len,
 257                                                                 name, lde, dir);
 258                                         if (ino)
 259                                                 goto found;
 260                                 } else
 261                                         pr_err("undefined filename size in inode.\n");
 262                         }
 263                         qnx6_put_page(page);
 264                 }
 265
 266                 if (++n >= npages)
 267                         n = 0;
 268         } while (n != start);
 269         return 0;
 270
 271 found:
 272         *res_page = page;
 273         ei->i_dir_start_lookup = n;
 274         return ino;
 275 }
 276
 277 const struct file_operations qnx6_dir_operations = {
 278         .llseek         = generic_file_llseek,
 279         .read           = generic_read_dir,
 280         .iterate        = qnx6_readdir,
 281         .fsync          = generic_file_fsync,
 282 };
 283
 284 const struct inode_operations qnx6_dir_inode_operations = {
 285         .lookup         = qnx6_lookup,
 286 };