GRUB2/MOD_SRC/grub-2.04/grub-core/fs/fshelp.c

   1 /* fshelp.c -- Filesystem helper functions */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2004,2005,2006,2007,2008  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/err.h>
  21 #include <grub/mm.h>
  22 #include <grub/misc.h>
  23 #include <grub/disk.h>
  24 #include <grub/fshelp.h>
  25 #include <grub/dl.h>
  26 #include <grub/i18n.h>
  27
  28 GRUB_MOD_LICENSE ("GPLv3+");
  29
  30 typedef int (*iterate_dir_func) (grub_fshelp_node_t dir,
  31                                  grub_fshelp_iterate_dir_hook_t hook,
  32                                  void *data);
  33 typedef grub_err_t (*lookup_file_func) (grub_fshelp_node_t dir,
  34                                         const char *name,
  35                                         grub_fshelp_node_t *foundnode,
  36                                         enum grub_fshelp_filetype *foundtype);
  37 typedef char *(*read_symlink_func) (grub_fshelp_node_t node);
  38
  39 struct stack_element {
  40   struct stack_element *parent;
  41   grub_fshelp_node_t node;
  42   enum grub_fshelp_filetype type;
  43 };
  44
  45 /* Context for grub_fshelp_find_file.  */
  46 struct grub_fshelp_find_file_ctx
  47 {
  48   /* Inputs.  */
  49   const char *path;
  50   grub_fshelp_node_t rootnode;
  51
  52   /* Global options. */
  53   int symlinknest;
  54
  55   /* Current file being traversed and its parents.  */
  56   struct stack_element *currnode;
  57 };
  58
  59 /* Helper for find_file_iter.  */
  60 static void
  61 free_node (grub_fshelp_node_t node, struct grub_fshelp_find_file_ctx *ctx)
  62 {
  63   if (node != ctx->rootnode)
  64     grub_free (node);
  65 }
  66
  67 static void
  68 pop_element (struct grub_fshelp_find_file_ctx *ctx)
  69 {
  70   struct stack_element *el;
  71   el = ctx->currnode;
  72   ctx->currnode = el->parent;
  73   free_node (el->node, ctx);
  74   grub_free (el);
  75 }
  76
  77 static void
  78 free_stack (struct grub_fshelp_find_file_ctx *ctx)
  79 {
  80   while (ctx->currnode)
  81     pop_element (ctx);
  82 }
  83
  84 static void
  85 go_up_a_level (struct grub_fshelp_find_file_ctx *ctx)
  86 {
  87   if (!ctx->currnode->parent)
  88     return;
  89   pop_element (ctx);
  90 }
  91
  92 static grub_err_t
  93 push_node (struct grub_fshelp_find_file_ctx *ctx, grub_fshelp_node_t node, enum grub_fshelp_filetype filetype)
  94 {
  95   struct stack_element *nst;
  96   nst = grub_malloc (sizeof (*nst));
  97   if (!nst)
  98     return grub_errno;
  99   nst->node = node;
 100   nst->type = filetype & ~GRUB_FSHELP_CASE_INSENSITIVE;
 101   nst->parent = ctx->currnode;
 102   ctx->currnode = nst;
 103   return GRUB_ERR_NONE;
 104 }
 105
 106 static grub_err_t
 107 go_to_root (struct grub_fshelp_find_file_ctx *ctx)
 108 {
 109   free_stack (ctx);
 110   return push_node (ctx, ctx->rootnode, GRUB_FSHELP_DIR);
 111 }
 112
 113 struct grub_fshelp_find_file_iter_ctx
 114 {
 115   const char *name;
 116   grub_fshelp_node_t *foundnode;
 117   enum grub_fshelp_filetype *foundtype;
 118 };
 119
 120 /* Helper for grub_fshelp_find_file.  */
 121 static int
 122 find_file_iter (const char *filename, enum grub_fshelp_filetype filetype,
 123                 grub_fshelp_node_t node, void *data)
 124 {
 125   struct grub_fshelp_find_file_iter_ctx *ctx = data;
 126
 127   if (filetype == GRUB_FSHELP_UNKNOWN ||
 128       ((filetype & GRUB_FSHELP_CASE_INSENSITIVE)
 129        ? grub_strcasecmp (ctx->name, filename)
 130        : grub_strcmp (ctx->name, filename)))
 131     {
 132       grub_free (node);
 133       return 0;
 134     }
 135
 136   /* The node is found, stop iterating over the nodes.  */
 137   *ctx->foundnode = node;
 138   *ctx->foundtype = filetype;
 139   return 1;
 140 }
 141
 142 static grub_err_t
 143 directory_find_file (grub_fshelp_node_t node, const char *name, grub_fshelp_node_t *foundnode,
 144                      enum grub_fshelp_filetype *foundtype, iterate_dir_func iterate_dir)
 145 {
 146   int found;
 147   struct grub_fshelp_find_file_iter_ctx ctx = {
 148     .foundnode = foundnode,
 149     .foundtype = foundtype,
 150     .name = name
 151   };
 152   found = iterate_dir (node, find_file_iter, &ctx);
 153   if (! found)
 154     {
 155       if (grub_errno)
 156         return grub_errno;
 157     }
 158   return GRUB_ERR_NONE;
 159 }
 160
 161 static grub_err_t
 162 find_file (char *currpath,
 163            iterate_dir_func iterate_dir, lookup_file_func lookup_file,
 164            read_symlink_func read_symlink,
 165            struct grub_fshelp_find_file_ctx *ctx)
 166 {
 167   char *name, *next;
 168   grub_err_t err;
 169   for (name = currpath; ; name = next)
 170     {
 171       char c;
 172       grub_fshelp_node_t foundnode = NULL;
 173       enum grub_fshelp_filetype foundtype = 0;
 174
 175       /* Remove all leading slashes.  */
 176       while (*name == '/')
 177         name++;
 178
 179       /* Found the node!  */
 180       if (! *name)
 181         return 0;
 182
 183       /* Extract the actual part from the pathname.  */
 184       for (next = name; *next && *next != '/'; next++);
 185
 186       /* At this point it is expected that the current node is a
 187          directory, check if this is true.  */
 188       if (ctx->currnode->type != GRUB_FSHELP_DIR)
 189         return grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("not a directory"));
 190
 191       /* Don't rely on fs providing actual . in the listing.  */
 192       if (next - name == 1 && name[0] == '.')
 193         continue;
 194
 195       /* Don't rely on fs providing actual .. in the listing.  */
 196       if (next - name == 2 && name[0] == '.' && name[1] == '.')
 197         {
 198           go_up_a_level (ctx);
 199           continue;
 200         }
 201
 202       /* Iterate over the directory.  */
 203       c = *next;
 204       *next = '\0';
 205       if (lookup_file)
 206         err = lookup_file (ctx->currnode->node, name, &foundnode, &foundtype);
 207       else
 208         err = directory_find_file (ctx->currnode->node, name, &foundnode, &foundtype, iterate_dir);
 209       *next = c;
 210
 211       if (err)
 212         return err;
 213
 214       if (!foundnode)
 215         break;
 216
 217       push_node (ctx, foundnode, foundtype);
 218
 219       /* Read in the symlink and follow it.  */
 220       if (ctx->currnode->type == GRUB_FSHELP_SYMLINK)
 221         {
 222           char *symlink;
 223
 224           /* Test if the symlink does not loop.  */
 225           if (++ctx->symlinknest == 8)
 226             return grub_error (GRUB_ERR_SYMLINK_LOOP,
 227                                N_("too deep nesting of symlinks"));
 228
 229           symlink = read_symlink (ctx->currnode->node);
 230
 231           if (!symlink)
 232             return grub_errno;
 233
 234           /* The symlink is an absolute path, go back to the root inode.  */
 235           if (symlink[0] == '/')
 236             {
 237               err = go_to_root (ctx);
 238               if (err)
 239                 return err;
 240             }
 241           else
 242             {
 243               /* Get from symlink to containing directory. */
 244               go_up_a_level (ctx);
 245             }
 246
 247
 248           /* Lookup the node the symlink points to.  */
 249           find_file (symlink, iterate_dir, lookup_file, read_symlink, ctx);
 250           grub_free (symlink);
 251
 252           if (grub_errno)
 253             return grub_errno;
 254         }
 255     }
 256
 257   return grub_error (GRUB_ERR_FILE_NOT_FOUND, N_("file `%s' not found"),
 258                      ctx->path);
 259 }
 260
 261 static grub_err_t
 262 grub_fshelp_find_file_real (const char *path, grub_fshelp_node_t rootnode,
 263                             grub_fshelp_node_t *foundnode,
 264                             iterate_dir_func iterate_dir,
 265                             lookup_file_func lookup_file,
 266                             read_symlink_func read_symlink,
 267                             enum grub_fshelp_filetype expecttype)
 268 {
 269   struct grub_fshelp_find_file_ctx ctx = {
 270     .path = path,
 271     .rootnode = rootnode,
 272     .symlinknest = 0,
 273     .currnode = 0
 274   };
 275   grub_err_t err;
 276   enum grub_fshelp_filetype foundtype;
 277   char *duppath;
 278
 279   if (!path || path[0] != '/')
 280     {
 281       return grub_error (GRUB_ERR_BAD_FILENAME, N_("invalid file name `%s'"), path);
 282     }
 283
 284   err = go_to_root (&ctx);
 285   if (err)
 286     return err;
 287
 288   duppath = grub_strdup (path);
 289   if (!duppath)
 290     return grub_errno;
 291   err = find_file (duppath, iterate_dir, lookup_file, read_symlink, &ctx);
 292   grub_free (duppath);
 293   if (err)
 294     {
 295       free_stack (&ctx);
 296       return err;
 297     }
 298
 299   *foundnode = ctx.currnode->node;
 300   foundtype = ctx.currnode->type;
 301   /* Avoid the node being freed.  */
 302   ctx.currnode->node = 0;
 303   free_stack (&ctx);
 304
 305   /* Check if the node that was found was of the expected type.  */
 306   if (expecttype == GRUB_FSHELP_REG && foundtype != expecttype)
 307     return grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("not a regular file"));
 308   else if (expecttype == GRUB_FSHELP_DIR && foundtype != expecttype)
 309     return grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("not a directory"));
 310
 311   return 0;
 312 }
 313
 314 /* Lookup the node PATH.  The node ROOTNODE describes the root of the
 315    directory tree.  The node found is returned in FOUNDNODE, which is
 316    either a ROOTNODE or a new malloc'ed node.  ITERATE_DIR is used to
 317    iterate over all directory entries in the current node.
 318    READ_SYMLINK is used to read the symlink if a node is a symlink.
 319    EXPECTTYPE is the type node that is expected by the called, an
 320    error is generated if the node is not of the expected type.  */
 321 grub_err_t
 322 grub_fshelp_find_file (const char *path, grub_fshelp_node_t rootnode,
 323                        grub_fshelp_node_t *foundnode,
 324                        iterate_dir_func iterate_dir,
 325                        read_symlink_func read_symlink,
 326                        enum grub_fshelp_filetype expecttype)
 327 {
 328   return grub_fshelp_find_file_real (path, rootnode, foundnode,
 329                                      iterate_dir, NULL,
 330                                      read_symlink, expecttype);
 331
 332 }
 333
 334 grub_err_t
 335 grub_fshelp_find_file_lookup (const char *path, grub_fshelp_node_t rootnode,
 336                               grub_fshelp_node_t *foundnode,
 337                               lookup_file_func lookup_file,
 338                               read_symlink_func read_symlink,
 339                               enum grub_fshelp_filetype expecttype)
 340 {
 341   return grub_fshelp_find_file_real (path, rootnode, foundnode,
 342                                      NULL, lookup_file,
 343                                      read_symlink, expecttype);
 344
 345 }
 346
 347 /* Read LEN bytes from the file NODE on disk DISK into the buffer BUF,
 348    beginning with the block POS.  READ_HOOK should be set before
 349    reading a block from the file.  READ_HOOK_DATA is passed through as
 350    the DATA argument to READ_HOOK.  GET_BLOCK is used to translate
 351    file blocks to disk blocks.  The file is FILESIZE bytes big and the
 352    blocks have a size of LOG2BLOCKSIZE (in log2).  */
 353 grub_ssize_t
 354 grub_fshelp_read_file (grub_disk_t disk, grub_fshelp_node_t node,
 355                        grub_disk_read_hook_t read_hook, void *read_hook_data,
 356                        grub_off_t pos, grub_size_t len, char *buf,
 357                        grub_disk_addr_t (*get_block) (grub_fshelp_node_t node,
 358                                                       grub_disk_addr_t block),
 359                        grub_off_t filesize, int log2blocksize,
 360                        grub_disk_addr_t blocks_start)
 361 {
 362   grub_disk_addr_t i, blockcnt;
 363   int blocksize = 1 << (log2blocksize + GRUB_DISK_SECTOR_BITS);
 364
 365   if (pos > filesize)
 366     {
 367       grub_error (GRUB_ERR_OUT_OF_RANGE,
 368                   N_("attempt to read past the end of file"));
 369       return -1;
 370     }
 371
 372   /* Adjust LEN so it we can't read past the end of the file.  */
 373   if (pos + len > filesize)
 374     len = filesize - pos;
 375
 376   blockcnt = ((len + pos) + blocksize - 1) >> (log2blocksize + GRUB_DISK_SECTOR_BITS);
 377
 378   for (i = pos >> (log2blocksize + GRUB_DISK_SECTOR_BITS); i < blockcnt; i++)
 379     {
 380       grub_disk_addr_t blknr;
 381       int blockoff = pos & (blocksize - 1);
 382       int blockend = blocksize;
 383
 384       int skipfirst = 0;
 385
 386       blknr = get_block (node, i);
 387       if (grub_errno)
 388         return -1;
 389
 390       blknr = blknr << log2blocksize;
 391
 392       /* Last block.  */
 393       if (i == blockcnt - 1)
 394         {
 395           blockend = (len + pos) & (blocksize - 1);
 396
 397           /* The last portion is exactly blocksize.  */
 398           if (! blockend)
 399             blockend = blocksize;
 400         }
 401
 402       /* First block.  */
 403       if (i == (pos >> (log2blocksize + GRUB_DISK_SECTOR_BITS)))
 404         {
 405           skipfirst = blockoff;
 406           blockend -= skipfirst;
 407         }
 408
 409       /* If the block number is 0 this block is not stored on disk but
 410          is zero filled instead.  */
 411       if (blknr)
 412         {
 413           disk->read_hook = read_hook;
 414           disk->read_hook_data = read_hook_data;
 415
 416           grub_disk_read (disk, blknr + blocks_start, skipfirst,
 417                           blockend, buf);
 418           disk->read_hook = 0;
 419           if (grub_errno)
 420             return -1;
 421         }
 422       else if (read_hook != (grub_disk_read_hook_t)grub_disk_blocklist_read)
 423         grub_memset (buf, 0, blockend);
 424
 425       buf += blocksize - skipfirst;
 426     }
 427
 428   return len;
 429 }