1 /* 2 * GRUB -- GRand Unified Bootloader 3 * Copyright (C) 1999, 2001, 2003 Free Software Foundation, Inc. 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 18 */ 19 20 #ifdef FSYS_EXT2FS 21 22 #include "shared.h" 23 #include "filesys.h" 24 25 static int mapblock1, mapblock2; 26 27 /* sizes are always in bytes, BLOCK values are always in DEV_BSIZE (sectors) */ 28 #define DEV_BSIZE 512 29 30 /* include/linux/fs.h */ 31 #define BLOCK_SIZE 1024 /* initial block size for superblock read */ 32 /* made up, defaults to 1 but can be passed via mount_opts */ 33 #define WHICH_SUPER 1 34 /* kind of from fs/ext2/super.c */ 35 #define SBLOCK (WHICH_SUPER * BLOCK_SIZE / DEV_BSIZE) /* = 2 */ 36 37 /* include/asm-i386/types.h */ 38 typedef __signed__ char __s8; 39 typedef unsigned char __u8; 40 typedef __signed__ short __s16; 41 typedef unsigned short __u16; 42 typedef __signed__ int __s32; 43 typedef unsigned int __u32; 44 45 /* 46 * Constants relative to the data blocks, from ext2_fs.h 47 */ 48 #define EXT2_NDIR_BLOCKS 12 49 #define EXT2_IND_BLOCK EXT2_NDIR_BLOCKS 50 #define EXT2_DIND_BLOCK (EXT2_IND_BLOCK + 1) 51 #define EXT2_TIND_BLOCK (EXT2_DIND_BLOCK + 1) 52 #define EXT2_N_BLOCKS (EXT2_TIND_BLOCK + 1) 53 54 /* include/linux/ext2_fs.h */ 55 struct ext2_super_block 56 { 57 __u32 s_inodes_count; /* Inodes count */ 58 __u32 s_blocks_count; /* Blocks count */ 59 __u32 s_r_blocks_count; /* Reserved blocks count */ 60 __u32 s_free_blocks_count; /* Free blocks count */ 61 __u32 s_free_inodes_count; /* Free inodes count */ 62 __u32 s_first_data_block; /* First Data Block */ 63 __u32 s_log_block_size; /* Block size */ 64 __s32 s_log_frag_size; /* Fragment size */ 65 __u32 s_blocks_per_group; /* # Blocks per group */ 66 __u32 s_frags_per_group; /* # Fragments per group */ 67 __u32 s_inodes_per_group; /* # Inodes per group */ 68 __u32 s_mtime; /* Mount time */ 69 __u32 s_wtime; /* Write time */ 70 __u16 s_mnt_count; /* Mount count */ 71 __s16 s_max_mnt_count; /* Maximal mount count */ 72 __u16 s_magic; /* Magic signature */ 73 __u16 s_state; /* File system state */ 74 __u16 s_errors; /* Behaviour when detecting errors */ 75 __u16 s_pad; 76 __u32 s_lastcheck; /* time of last check */ 77 __u32 s_checkinterval; /* max. time between checks */ 78 __u32 s_creator_os; /* OS */ 79 __u32 s_rev_level; /* Revision level */ 80 __u16 s_def_resuid; /* Default uid for reserved blocks */ 81 __u16 s_def_resgid; /* Default gid for reserved blocks */ 82 __u32 s_reserved[235]; /* Padding to the end of the block */ 83 }; 84 85 struct ext2_group_desc 86 { 87 __u32 bg_block_bitmap; /* Blocks bitmap block */ 88 __u32 bg_inode_bitmap; /* Inodes bitmap block */ 89 __u32 bg_inode_table; /* Inodes table block */ 90 __u16 bg_free_blocks_count; /* Free blocks count */ 91 __u16 bg_free_inodes_count; /* Free inodes count */ 92 __u16 bg_used_dirs_count; /* Directories count */ 93 __u16 bg_pad; 94 __u32 bg_reserved[3]; 95 }; 96 97 struct ext2_inode 98 { 99 __u16 i_mode; /* File mode */ 100 __u16 i_uid; /* Owner Uid */ 101 __u32 i_size; /* 4: Size in bytes */ 102 __u32 i_atime; /* Access time */ 103 __u32 i_ctime; /* 12: Creation time */ 104 __u32 i_mtime; /* Modification time */ 105 __u32 i_dtime; /* 20: Deletion Time */ 106 __u16 i_gid; /* Group Id */ 107 __u16 i_links_count; /* 24: Links count */ 108 __u32 i_blocks; /* Blocks count */ 109 __u32 i_flags; /* 32: File flags */ 110 union 111 { 112 struct 113 { 114 __u32 l_i_reserved1; 115 } 116 linux1; 117 struct 118 { 119 __u32 h_i_translator; 120 } 121 hurd1; 122 struct 123 { 124 __u32 m_i_reserved1; 125 } 126 masix1; 127 } 128 osd1; /* OS dependent 1 */ 129 __u32 i_block[EXT2_N_BLOCKS]; /* 40: Pointers to blocks */ 130 __u32 i_version; /* File version (for NFS) */ 131 __u32 i_file_acl; /* File ACL */ 132 __u32 i_dir_acl; /* Directory ACL */ 133 __u32 i_faddr; /* Fragment address */ 134 union 135 { 136 struct 137 { 138 __u8 l_i_frag; /* Fragment number */ 139 __u8 l_i_fsize; /* Fragment size */ 140 __u16 i_pad1; 141 __u32 l_i_reserved2[2]; 142 } 143 linux2; 144 struct 145 { 146 __u8 h_i_frag; /* Fragment number */ 147 __u8 h_i_fsize; /* Fragment size */ 148 __u16 h_i_mode_high; 149 __u16 h_i_uid_high; 150 __u16 h_i_gid_high; 151 __u32 h_i_author; 152 } 153 hurd2; 154 struct 155 { 156 __u8 m_i_frag; /* Fragment number */ 157 __u8 m_i_fsize; /* Fragment size */ 158 __u16 m_pad1; 159 __u32 m_i_reserved2[2]; 160 } 161 masix2; 162 } 163 osd2; /* OS dependent 2 */ 164 }; 165 166 /* linux/limits.h */ 167 #define NAME_MAX 255 /* # chars in a file name */ 168 169 /* linux/posix_type.h */ 170 typedef long linux_off_t; 171 172 /* linux/ext2fs.h */ 173 #define EXT2_NAME_LEN 255 174 struct ext2_dir_entry 175 { 176 __u32 inode; /* Inode number */ 177 __u16 rec_len; /* Directory entry length */ 178 __u8 name_len; /* Name length */ 179 __u8 file_type; 180 char name[EXT2_NAME_LEN]; /* File name */ 181 }; 182 183 /* linux/ext2fs.h */ 184 /* 185 * EXT2_DIR_PAD defines the directory entries boundaries 186 * 187 * NOTE: It must be a multiple of 4 188 */ 189 #define EXT2_DIR_PAD 4 190 #define EXT2_DIR_ROUND (EXT2_DIR_PAD - 1) 191 #define EXT2_DIR_REC_LEN(name_len) (((name_len) + 8 + EXT2_DIR_ROUND) & \ 192 ~EXT2_DIR_ROUND) 193 194 195 /* ext2/super.c */ 196 #define log2(n) ffz(~(n)) 197 198 #define EXT2_SUPER_MAGIC 0xEF53 /* include/linux/ext2_fs.h */ 199 #define EXT2_ROOT_INO 2 /* include/linux/ext2_fs.h */ 200 #define PATH_MAX 1024 /* include/linux/limits.h */ 201 #define MAX_LINK_COUNT 5 /* number of symbolic links to follow */ 202 203 /* made up, these are pointers into FSYS_BUF */ 204 /* read once, always stays there: */ 205 #define SUPERBLOCK \ 206 ((struct ext2_super_block *)(FSYS_BUF)) 207 #define GROUP_DESC \ 208 ((struct ext2_group_desc *) \ 209 ((int)SUPERBLOCK + sizeof(struct ext2_super_block))) 210 #define INODE \ 211 ((struct ext2_inode *)((int)GROUP_DESC + EXT2_BLOCK_SIZE(SUPERBLOCK))) 212 #define DATABLOCK1 \ 213 ((int)((int)INODE + sizeof(struct ext2_inode))) 214 #define DATABLOCK2 \ 215 ((int)((int)DATABLOCK1 + EXT2_BLOCK_SIZE(SUPERBLOCK))) 216 217 /* linux/ext2_fs.h */ 218 #define EXT2_ADDR_PER_BLOCK(s) (EXT2_BLOCK_SIZE(s) / sizeof (__u32)) 219 #define EXT2_ADDR_PER_BLOCK_BITS(s) (log2(EXT2_ADDR_PER_BLOCK(s))) 220 221 /* linux/ext2_fs.h */ 222 #define EXT2_BLOCK_SIZE_BITS(s) ((s)->s_log_block_size + 10) 223 /* kind of from ext2/super.c */ 224 #define EXT2_BLOCK_SIZE(s) (1 << EXT2_BLOCK_SIZE_BITS(s)) 225 /* linux/ext2fs.h */ 226 #define EXT2_DESC_PER_BLOCK(s) \ 227 (EXT2_BLOCK_SIZE(s) / sizeof (struct ext2_group_desc)) 228 /* linux/stat.h */ 229 #define S_IFMT 00170000 230 #define S_IFLNK 0120000 231 #define S_IFREG 0100000 232 #define S_IFDIR 0040000 233 #define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK) 234 #define S_ISREG(m) (((m) & S_IFMT) == S_IFREG) 235 #define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR) 236 237 /* include/asm-i386/bitops.h */ 238 /* 239 * ffz = Find First Zero in word. Undefined if no zero exists, 240 * so code should check against ~0UL first.. 241 */ 242 static __inline__ unsigned long 243 ffz (unsigned long word) 244 { 245 __asm__ ("bsfl %1,%0" 246 : "=r" (word) 247 : "r" (~word)); 248 return word; 249 } 250 251 /* check filesystem types and read superblock into memory buffer */ 252 int 253 ext2fs_mount (void) 254 { 255 int retval = 1; 256 257 if ((((current_drive & 0x80) || (current_slice != 0)) 258 && (current_slice != PC_SLICE_TYPE_EXT2FS) 259 && (current_slice != PC_SLICE_TYPE_LINUX_RAID) 260 && (! IS_PC_SLICE_TYPE_BSD_WITH_FS (current_slice, FS_EXT2FS)) 261 && (! IS_PC_SLICE_TYPE_BSD_WITH_FS (current_slice, FS_OTHER))) 262 || part_length < (SBLOCK + (sizeof (struct ext2_super_block) / DEV_BSIZE)) 263 || !devread (SBLOCK, 0, sizeof (struct ext2_super_block), 264 (char *) SUPERBLOCK) 265 || SUPERBLOCK->s_magic != EXT2_SUPER_MAGIC) 266 retval = 0; 267 268 return retval; 269 } 270 271 /* Takes a file system block number and reads it into BUFFER. */ 272 static int 273 ext2_rdfsb (int fsblock, int buffer) 274 { 275 #ifdef E2DEBUG 276 printf ("fsblock %d buffer %d\n", fsblock, buffer); 277 #endif /* E2DEBUG */ 278 return devread (fsblock * (EXT2_BLOCK_SIZE (SUPERBLOCK) / DEV_BSIZE), 0, 279 EXT2_BLOCK_SIZE (SUPERBLOCK), (char *) buffer); 280 } 281 282 /* from 283 ext2/inode.c:ext2_bmap() 284 */ 285 /* Maps LOGICAL_BLOCK (the file offset divided by the blocksize) into 286 a physical block (the location in the file system) via an inode. */ 287 static int 288 ext2fs_block_map (int logical_block) 289 { 290 291 #ifdef E2DEBUG 292 unsigned char *i; 293 for (i = (unsigned char *) INODE; 294 i < ((unsigned char *) INODE + sizeof (struct ext2_inode)); 295 i++) 296 { 297 printf ("%c", "0123456789abcdef"[*i >> 4]); 298 printf ("%c", "0123456789abcdef"[*i % 16]); 299 if (!((i + 1 - (unsigned char *) INODE) % 16)) 300 { 301 printf ("\n"); 302 } 303 else 304 { 305 printf (" "); 306 } 307 } 308 printf ("logical block %d\n", logical_block); 309 #endif /* E2DEBUG */ 310 311 /* if it is directly pointed to by the inode, return that physical addr */ 312 if (logical_block < EXT2_NDIR_BLOCKS) 313 { 314 #ifdef E2DEBUG 315 printf ("returning %d\n", (unsigned char *) (INODE->i_block[logical_block])); 316 printf ("returning %d\n", INODE->i_block[logical_block]); 317 #endif /* E2DEBUG */ 318 return INODE->i_block[logical_block]; 319 } 320 /* else */ 321 logical_block -= EXT2_NDIR_BLOCKS; 322 /* try the indirect block */ 323 if (logical_block < EXT2_ADDR_PER_BLOCK (SUPERBLOCK)) 324 { 325 if (mapblock1 != 1 326 && !ext2_rdfsb (INODE->i_block[EXT2_IND_BLOCK], DATABLOCK1)) 327 { 328 errnum = ERR_FSYS_CORRUPT; 329 return -1; 330 } 331 mapblock1 = 1; 332 return ((__u32 *) DATABLOCK1)[logical_block]; 333 } 334 /* else */ 335 logical_block -= EXT2_ADDR_PER_BLOCK (SUPERBLOCK); 336 /* now try the double indirect block */ 337 if (logical_block < (1 << (EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK) * 2))) 338 { 339 int bnum; 340 if (mapblock1 != 2 341 && !ext2_rdfsb (INODE->i_block[EXT2_DIND_BLOCK], DATABLOCK1)) 342 { 343 errnum = ERR_FSYS_CORRUPT; 344 return -1; 345 } 346 mapblock1 = 2; 347 if ((bnum = (((__u32 *) DATABLOCK1) 348 [logical_block >> EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK)])) 349 != mapblock2 350 && !ext2_rdfsb (bnum, DATABLOCK2)) 351 { 352 errnum = ERR_FSYS_CORRUPT; 353 return -1; 354 } 355 mapblock2 = bnum; 356 return ((__u32 *) DATABLOCK2) 357 [logical_block & (EXT2_ADDR_PER_BLOCK (SUPERBLOCK) - 1)]; 358 } 359 /* else */ 360 mapblock2 = -1; 361 logical_block -= (1 << (EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK) * 2)); 362 if (mapblock1 != 3 363 && !ext2_rdfsb (INODE->i_block[EXT2_TIND_BLOCK], DATABLOCK1)) 364 { 365 errnum = ERR_FSYS_CORRUPT; 366 return -1; 367 } 368 mapblock1 = 3; 369 if (!ext2_rdfsb (((__u32 *) DATABLOCK1) 370 [logical_block >> (EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK) 371 * 2)], 372 DATABLOCK2)) 373 { 374 errnum = ERR_FSYS_CORRUPT; 375 return -1; 376 } 377 if (!ext2_rdfsb (((__u32 *) DATABLOCK2) 378 [(logical_block >> EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK)) 379 & (EXT2_ADDR_PER_BLOCK (SUPERBLOCK) - 1)], 380 DATABLOCK2)) 381 { 382 errnum = ERR_FSYS_CORRUPT; 383 return -1; 384 } 385 return ((__u32 *) DATABLOCK2) 386 [logical_block & (EXT2_ADDR_PER_BLOCK (SUPERBLOCK) - 1)]; 387 } 388 389 /* preconditions: all preconds of ext2fs_block_map */ 390 int 391 ext2fs_read (char *buf, int len) 392 { 393 int logical_block; 394 int offset; 395 int map; 396 int ret = 0; 397 int size = 0; 398 399 #ifdef E2DEBUG 400 static char hexdigit[] = "0123456789abcdef"; 401 unsigned char *i; 402 for (i = (unsigned char *) INODE; 403 i < ((unsigned char *) INODE + sizeof (struct ext2_inode)); 404 i++) 405 { 406 printf ("%c", hexdigit[*i >> 4]); 407 printf ("%c", hexdigit[*i % 16]); 408 if (!((i + 1 - (unsigned char *) INODE) % 16)) 409 { 410 printf ("\n"); 411 } 412 else 413 { 414 printf (" "); 415 } 416 } 417 #endif /* E2DEBUG */ 418 while (len > 0) 419 { 420 /* find the (logical) block component of our location */ 421 logical_block = filepos >> EXT2_BLOCK_SIZE_BITS (SUPERBLOCK); 422 offset = filepos & (EXT2_BLOCK_SIZE (SUPERBLOCK) - 1); 423 map = ext2fs_block_map (logical_block); 424 #ifdef E2DEBUG 425 printf ("map=%d\n", map); 426 #endif /* E2DEBUG */ 427 if (map < 0) 428 break; 429 430 size = EXT2_BLOCK_SIZE (SUPERBLOCK); 431 size -= offset; 432 if (size > len) 433 size = len; 434 435 if (map == 0) { 436 memset ((char *) buf, 0, size); 437 } else { 438 disk_read_func = disk_read_hook; 439 440 devread (map * (EXT2_BLOCK_SIZE (SUPERBLOCK) / DEV_BSIZE), 441 offset, size, buf); 442 443 disk_read_func = NULL; 444 } 445 446 buf += size; 447 len -= size; 448 filepos += size; 449 ret += size; 450 } 451 452 if (errnum) 453 ret = 0; 454 455 return ret; 456 } 457 458 459 /* Based on: 460 def_blk_fops points to 461 blkdev_open, which calls (I think): 462 sys_open() 463 do_open() 464 open_namei() 465 dir_namei() which accesses current->fs->root 466 fs->root was set during original mount: 467 (something)... which calls (I think): 468 ext2_read_super() 469 iget() 470 __iget() 471 read_inode() 472 ext2_read_inode() 473 uses desc_per_block_bits, which is set in ext2_read_super() 474 also uses group descriptors loaded during ext2_read_super() 475 lookup() 476 ext2_lookup() 477 ext2_find_entry() 478 ext2_getblk() 479 480 */ 481 482 static inline 483 int ext2_is_fast_symlink (void) 484 { 485 int ea_blocks; 486 ea_blocks = INODE->i_file_acl ? EXT2_BLOCK_SIZE (SUPERBLOCK) / DEV_BSIZE : 0; 487 return INODE->i_blocks == ea_blocks; 488 } 489 490 /* preconditions: ext2fs_mount already executed, therefore supblk in buffer 491 * known as SUPERBLOCK 492 * returns: 0 if error, nonzero iff we were able to find the file successfully 493 * postconditions: on a nonzero return, buffer known as INODE contains the 494 * inode of the file we were trying to look up 495 * side effects: messes up GROUP_DESC buffer area 496 */ 497 int 498 ext2fs_dir (char *dirname) 499 { 500 int current_ino = EXT2_ROOT_INO; /* start at the root */ 501 int updir_ino = current_ino; /* the parent of the current directory */ 502 int group_id; /* which group the inode is in */ 503 int group_desc; /* fs pointer to that group */ 504 int desc; /* index within that group */ 505 int ino_blk; /* fs pointer of the inode's information */ 506 int str_chk = 0; /* used to hold the results of a string compare */ 507 struct ext2_group_desc *gdp; 508 struct ext2_inode *raw_inode; /* inode info corresponding to current_ino */ 509 510 char linkbuf[PATH_MAX]; /* buffer for following symbolic links */ 511 int link_count = 0; 512 513 char *rest; 514 char ch; /* temp char holder */ 515 516 int off; /* offset within block of directory entry (off mod blocksize) */ 517 int loc; /* location within a directory */ 518 int blk; /* which data blk within dir entry (off div blocksize) */ 519 long map; /* fs pointer of a particular block from dir entry */ 520 struct ext2_dir_entry *dp; /* pointer to directory entry */ 521 #ifdef E2DEBUG 522 unsigned char *i; 523 #endif /* E2DEBUG */ 524 525 /* loop invariants: 526 current_ino = inode to lookup 527 dirname = pointer to filename component we are cur looking up within 528 the directory known pointed to by current_ino (if any) 529 */ 530 531 while (1) 532 { 533 #ifdef E2DEBUG 534 printf ("inode %d\n", current_ino); 535 printf ("dirname=%s\n", dirname); 536 #endif /* E2DEBUG */ 537 538 /* look up an inode */ 539 group_id = (current_ino - 1) / (SUPERBLOCK->s_inodes_per_group); 540 group_desc = group_id >> log2 (EXT2_DESC_PER_BLOCK (SUPERBLOCK)); 541 desc = group_id & (EXT2_DESC_PER_BLOCK (SUPERBLOCK) - 1); 542 #ifdef E2DEBUG 543 printf ("ipg=%d, dpb=%d\n", SUPERBLOCK->s_inodes_per_group, 544 EXT2_DESC_PER_BLOCK (SUPERBLOCK)); 545 printf ("group_id=%d group_desc=%d desc=%d\n", group_id, group_desc, desc); 546 #endif /* E2DEBUG */ 547 if (!ext2_rdfsb ( 548 (WHICH_SUPER + group_desc + SUPERBLOCK->s_first_data_block), 549 (int) GROUP_DESC)) 550 { 551 return 0; 552 } 553 gdp = GROUP_DESC; 554 ino_blk = gdp[desc].bg_inode_table + 555 (((current_ino - 1) % (SUPERBLOCK->s_inodes_per_group)) 556 >> log2 (EXT2_BLOCK_SIZE (SUPERBLOCK) / sizeof (struct ext2_inode))); 557 #ifdef E2DEBUG 558 printf ("inode table fsblock=%d\n", ino_blk); 559 #endif /* E2DEBUG */ 560 if (!ext2_rdfsb (ino_blk, (int) INODE)) 561 { 562 return 0; 563 } 564 565 /* reset indirect blocks! */ 566 mapblock2 = mapblock1 = -1; 567 568 raw_inode = INODE + 569 ((current_ino - 1) 570 & (EXT2_BLOCK_SIZE (SUPERBLOCK) / sizeof (struct ext2_inode) - 1)); 571 #ifdef E2DEBUG 572 printf ("ipb=%d, sizeof(inode)=%d\n", 573 (EXT2_BLOCK_SIZE (SUPERBLOCK) / sizeof (struct ext2_inode)), 574 sizeof (struct ext2_inode)); 575 printf ("inode=%x, raw_inode=%x\n", INODE, raw_inode); 576 printf ("offset into inode table block=%d\n", (int) raw_inode - (int) INODE); 577 for (i = (unsigned char *) INODE; i <= (unsigned char *) raw_inode; 578 i++) 579 { 580 printf ("%c", "0123456789abcdef"[*i >> 4]); 581 printf ("%c", "0123456789abcdef"[*i % 16]); 582 if (!((i + 1 - (unsigned char *) INODE) % 16)) 583 { 584 printf ("\n"); 585 } 586 else 587 { 588 printf (" "); 589 } 590 } 591 printf ("first word=%x\n", *((int *) raw_inode)); 592 #endif /* E2DEBUG */ 593 594 /* copy inode to fixed location */ 595 memmove ((void *) INODE, (void *) raw_inode, sizeof (struct ext2_inode)); 596 597 #ifdef E2DEBUG 598 printf ("first word=%x\n", *((int *) INODE)); 599 #endif /* E2DEBUG */ 600 601 /* If we've got a symbolic link, then chase it. */ 602 if (S_ISLNK (INODE->i_mode)) 603 { 604 int len; 605 if (++link_count > MAX_LINK_COUNT) 606 { 607 errnum = ERR_SYMLINK_LOOP; 608 return 0; 609 } 610 611 /* Find out how long our remaining name is. */ 612 len = 0; 613 while (dirname[len] && !isspace (dirname[len])) 614 len++; 615 616 /* Get the symlink size. */ 617 filemax = (INODE->i_size); 618 if (filemax + len > sizeof (linkbuf) - 2) 619 { 620 errnum = ERR_FILELENGTH; 621 return 0; 622 } 623 624 if (len) 625 { 626 /* Copy the remaining name to the end of the symlink data. 627 Note that DIRNAME and LINKBUF may overlap! */ 628 memmove (linkbuf + filemax, dirname, len); 629 } 630 linkbuf[filemax + len] = '\0'; 631 632 /* Read the symlink data. */ 633 if (! ext2_is_fast_symlink ()) 634 { 635 /* Read the necessary blocks, and reset the file pointer. */ 636 len = grub_read (linkbuf, filemax); 637 filepos = 0; 638 if (!len) 639 return 0; 640 } 641 else 642 { 643 /* Copy the data directly from the inode. */ 644 len = filemax; 645 memmove (linkbuf, (char *) INODE->i_block, len); 646 } 647 648 #ifdef E2DEBUG 649 printf ("symlink=%s\n", linkbuf); 650 #endif 651 652 dirname = linkbuf; 653 if (*dirname == '/') 654 { 655 /* It's an absolute link, so look it up in root. */ 656 current_ino = EXT2_ROOT_INO; 657 updir_ino = current_ino; 658 } 659 else 660 { 661 /* Relative, so look it up in our parent directory. */ 662 current_ino = updir_ino; 663 } 664 665 /* Try again using the new name. */ 666 continue; 667 } 668 669 /* if end of filename, INODE points to the file's inode */ 670 if (!*dirname || isspace (*dirname)) 671 { 672 if (!S_ISREG (INODE->i_mode)) 673 { 674 errnum = ERR_BAD_FILETYPE; 675 return 0; 676 } 677 678 filemax = (INODE->i_size); 679 return 1; 680 } 681 682 /* else we have to traverse a directory */ 683 updir_ino = current_ino; 684 685 /* skip over slashes */ 686 while (*dirname == '/') 687 dirname++; 688 689 /* if this isn't a directory of sufficient size to hold our file, abort */ 690 if (!(INODE->i_size) || !S_ISDIR (INODE->i_mode)) 691 { 692 errnum = ERR_BAD_FILETYPE; 693 return 0; 694 } 695 696 /* skip to next slash or end of filename (space) */ 697 for (rest = dirname; (ch = *rest) && !isspace (ch) && ch != '/'; 698 rest++); 699 700 /* look through this directory and find the next filename component */ 701 /* invariant: rest points to slash after the next filename component */ 702 *rest = 0; 703 loc = 0; 704 705 do 706 { 707 708 #ifdef E2DEBUG 709 printf ("dirname=%s, rest=%s, loc=%d\n", dirname, rest, loc); 710 #endif /* E2DEBUG */ 711 712 /* if our location/byte offset into the directory exceeds the size, 713 give up */ 714 if (loc >= INODE->i_size) 715 { 716 if (print_possibilities < 0) 717 { 718 # if 0 719 putchar ('\n'); 720 # endif 721 } 722 else 723 { 724 errnum = ERR_FILE_NOT_FOUND; 725 *rest = ch; 726 } 727 return (print_possibilities < 0); 728 } 729 730 /* else, find the (logical) block component of our location */ 731 blk = loc >> EXT2_BLOCK_SIZE_BITS (SUPERBLOCK); 732 733 /* we know which logical block of the directory entry we are looking 734 for, now we have to translate that to the physical (fs) block on 735 the disk */ 736 map = ext2fs_block_map (blk); 737 #ifdef E2DEBUG 738 printf ("fs block=%d\n", map); 739 #endif /* E2DEBUG */ 740 mapblock2 = -1; 741 if ((map < 0) || !ext2_rdfsb (map, DATABLOCK2)) 742 { 743 errnum = ERR_FSYS_CORRUPT; 744 *rest = ch; 745 return 0; 746 } 747 off = loc & (EXT2_BLOCK_SIZE (SUPERBLOCK) - 1); 748 dp = (struct ext2_dir_entry *) (DATABLOCK2 + off); 749 /* advance loc prematurely to next on-disk directory entry */ 750 loc += dp->rec_len; 751 752 /* NOTE: ext2fs filenames are NOT null-terminated */ 753 754 #ifdef E2DEBUG 755 printf ("directory entry ino=%d\n", dp->inode); 756 if (dp->inode) 757 printf ("entry=%s\n", dp->name); 758 #endif /* E2DEBUG */ 759 760 if (dp->inode) 761 { 762 int saved_c = dp->name[dp->name_len]; 763 764 dp->name[dp->name_len] = 0; 765 str_chk = substring (dirname, dp->name); 766 767 # ifndef STAGE1_5 768 if (print_possibilities && ch != '/' 769 && (!*dirname || str_chk <= 0)) 770 { 771 if (print_possibilities > 0) 772 print_possibilities = -print_possibilities; 773 print_a_completion (dp->name); 774 } 775 # endif 776 777 dp->name[dp->name_len] = saved_c; 778 } 779 780 } 781 while (!dp->inode || (str_chk || (print_possibilities && ch != '/'))); 782 783 current_ino = dp->inode; 784 *(dirname = rest) = ch; 785 } 786 /* never get here */ 787 } 788 789 #endif /* FSYS_EXT2_FS */ 790
