1 /*- 2 * Copyright (c) 1992 Keith Muller. 3 * Copyright (c) 1992, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Keith Muller of the University of California, San Diego. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by the University of 20 * California, Berkeley and its contributors. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * $Id: file_subs.c,v 1.4 1995/10/23 21:23:06 ache Exp $ 38 */ 39 40 #ifndef lint 41 static char const sccsid[] = "@(#)file_subs.c 8.1 (Berkeley) 5/31/93"; 42 #endif /* not lint */ 43 44 #include <sys/types.h> 45 #include <sys/time.h> 46 #include <sys/stat.h> 47 #include <unistd.h> 48 #include <sys/param.h> 49 #include <fcntl.h> 50 #include <string.h> 51 #include <stdio.h> 52 #include <errno.h> 53 #include <sys/uio.h> 54 #include <stdlib.h> 55 #include "pax.h" 56 #include "extern.h" 57 58 static int 59 mk_link __P((register char *,register struct stat *,register char *, int)); 60 61 /* 62 * routines that deal with file operations such as: creating, removing; 63 * and setting access modes, uid/gid and times of files 64 */ 65 66 #define FILEBITS (S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO) 67 #define SETBITS (S_ISUID | S_ISGID) 68 #define ABITS (FILEBITS | SETBITS) 69 70 /* 71 * file_creat() 72 * Create and open a file. 73 * Return: 74 * file descriptor or -1 for failure 75 */ 76 77 #if __STDC__ 78 int 79 file_creat(register ARCHD *arcn) 80 #else 81 int 82 file_creat(arcn) 83 register ARCHD *arcn; 84 #endif 85 { 86 int fd = -1; 87 mode_t file_mode; 88 int oerrno; 89 90 /* 91 * assume file doesn't exist, so just try to create it, most times this 92 * works. We have to take special handling when the file does exist. To 93 * detect this, we use O_EXCL. For example when trying to create a 94 * file and a character device or fifo exists with the same name, we 95 * can accidently open the device by mistake (or block waiting to open) 96 * If we find that the open has failed, then figure spend the effore to 97 * figure out why. This strategy was found to have better average 98 * performance in common use than checking the file (and the path) 99 * first with lstat. 100 */ 101 file_mode = arcn->sb.st_mode & FILEBITS; 102 if ((fd = open(arcn->name, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 103 file_mode)) >= 0) 104 return(fd); 105 106 /* 107 * the file seems to exist. First we try to get rid of it (found to be 108 * the second most common failure when traced). If this fails, only 109 * then we go to the expense to check and create the path to the file 110 */ 111 if (unlnk_exist(arcn->name, arcn->type) != 0) 112 return(-1); 113 114 for (;;) { 115 /* 116 * try to open it again, if this fails, check all the nodes in 117 * the path and give it a final try. if chk_path() finds that 118 * it cannot fix anything, we will skip the last attempt 119 */ 120 if ((fd = open(arcn->name, O_WRONLY | O_CREAT | O_TRUNC, 121 file_mode)) >= 0) 122 break; 123 oerrno = errno; 124 if (chk_path(arcn->name,arcn->sb.st_uid,arcn->sb.st_gid) < 0) { 125 syswarn(1, oerrno, "Unable to create %s", arcn->name); 126 return(-1); 127 } 128 } 129 return(fd); 130 } 131 132 /* 133 * file_close() 134 * Close file descriptor to a file just created by pax. Sets modes, 135 * ownership and times as required. 136 * Return: 137 * 0 for success, -1 for failure 138 */ 139 140 #if __STDC__ 141 void 142 file_close(register ARCHD *arcn, int fd) 143 #else 144 void 145 file_close(arcn, fd) 146 register ARCHD *arcn; 147 int fd; 148 #endif 149 { 150 int res = 0; 151 152 if (fd < 0) 153 return; 154 if (close(fd) < 0) 155 syswarn(0, errno, "Unable to close file descriptor on %s", 156 arcn->name); 157 158 /* 159 * set owner/groups first as this may strip off mode bits we want 160 * then set file permission modes. Then set file access and 161 * modification times. 162 */ 163 if (pids) 164 res = set_ids(arcn->name, arcn->sb.st_uid, arcn->sb.st_gid); 165 166 /* 167 * IMPORTANT SECURITY NOTE: 168 * if not preserving mode or we cannot set uid/gid, then PROHIBIT 169 * set uid/gid bits 170 */ 171 if (!pmode || res) 172 arcn->sb.st_mode &= ~(SETBITS); 173 if (pmode) 174 set_pmode(arcn->name, arcn->sb.st_mode); 175 if (patime || pmtime) 176 set_ftime(arcn->name, arcn->sb.st_mtime, arcn->sb.st_atime, 0); 177 } 178 179 /* 180 * lnk_creat() 181 * Create a hard link to arcn->ln_name from arcn->name. arcn->ln_name 182 * must exist; 183 * Return: 184 * 0 if ok, -1 otherwise 185 */ 186 187 #if __STDC__ 188 int 189 lnk_creat(register ARCHD *arcn) 190 #else 191 int 192 lnk_creat(arcn) 193 register ARCHD *arcn; 194 #endif 195 { 196 struct stat sb; 197 198 /* 199 * we may be running as root, so we have to be sure that link target 200 * is not a directory, so we lstat and check 201 */ 202 if (lstat(arcn->ln_name, &sb) < 0) { 203 syswarn(1,errno,"Unable to link to %s from %s", arcn->ln_name, 204 arcn->name); 205 return(-1); 206 } 207 208 if (S_ISDIR(sb.st_mode)) { 209 warn(1, "A hard link to the directory %s is not allowed", 210 arcn->ln_name); 211 return(-1); 212 } 213 214 return(mk_link(arcn->ln_name, &sb, arcn->name, 0)); 215 } 216 217 /* 218 * cross_lnk() 219 * Create a hard link to arcn->org_name from arcn->name. Only used in copy 220 * with the -l flag. No warning or error if this does not succeed (we will 221 * then just create the file) 222 * Return: 223 * 1 if copy() should try to create this file node 224 * 0 if cross_lnk() ok, -1 for fatal flaw (like linking to self). 225 */ 226 227 #if __STDC__ 228 int 229 cross_lnk(register ARCHD *arcn) 230 #else 231 int 232 cross_lnk(arcn) 233 register ARCHD *arcn; 234 #endif 235 { 236 /* 237 * try to make a link to orginal file (-l flag in copy mode). make sure 238 * we do not try to link to directories in case we are running as root 239 * (and it might succeed). 240 */ 241 if (arcn->type == PAX_DIR) 242 return(1); 243 return(mk_link(arcn->org_name, &(arcn->sb), arcn->name, 1)); 244 } 245 246 /* 247 * chk_same() 248 * In copy mode if we are not trying to make hard links between the src 249 * and destinations, make sure we are not going to overwrite ourselves by 250 * accident. This slows things down a little, but we have to protect all 251 * those people who make typing errors. 252 * Return: 253 * 1 the target does not exist, go ahead and copy 254 * 0 skip it file exists (-k) or may be the same as source file 255 */ 256 257 #if __STDC__ 258 int 259 chk_same(register ARCHD *arcn) 260 #else 261 int 262 chk_same(arcn) 263 register ARCHD *arcn; 264 #endif 265 { 266 struct stat sb; 267 268 /* 269 * if file does not exist, return. if file exists and -k, skip it 270 * quietly 271 */ 272 if (lstat(arcn->name, &sb) < 0) 273 return(1); 274 if (kflag) 275 return(0); 276 277 /* 278 * better make sure the user does not have src == dest by mistake 279 */ 280 if ((arcn->sb.st_dev == sb.st_dev) && (arcn->sb.st_ino == sb.st_ino)) { 281 warn(1, "Unable to copy %s, file would overwrite itself", 282 arcn->name); 283 return(0); 284 } 285 return(1); 286 } 287 288 /* 289 * mk_link() 290 * try to make a hard link between two files. if ign set, we do not 291 * complain. 292 * Return: 293 * 0 if successful (or we are done with this file but no error, such as 294 * finding the from file exists and the user has set -k). 295 * 1 when ign was set to indicates we could not make the link but we 296 * should try to copy/extract the file as that might work (and is an 297 * allowed option). -1 an error occurred. 298 */ 299 300 #if __STDC__ 301 static int 302 mk_link(register char *to, register struct stat *to_sb, register char *from, 303 int ign) 304 #else 305 static int 306 mk_link(to, to_sb, from, ign) 307 register char *to; 308 register struct stat *to_sb; 309 register char *from; 310 int ign; 311 #endif 312 { 313 struct stat sb; 314 int oerrno; 315 316 /* 317 * if from file exists, it has to be unlinked to make the link. If the 318 * file exists and -k is set, skip it quietly 319 */ 320 if (lstat(from, &sb) == 0) { 321 if (kflag) 322 return(0); 323 324 /* 325 * make sure it is not the same file, protect the user 326 */ 327 if ((to_sb->st_dev==sb.st_dev)&&(to_sb->st_ino == sb.st_ino)) { 328 warn(1, "Unable to link file %s to itself", to); 329 return(-1);; 330 } 331 332 /* 333 * try to get rid of the file, based on the type 334 */ 335 if (S_ISDIR(sb.st_mode)) { 336 if (rmdir(from) < 0) { 337 syswarn(1, errno, "Unable to remove %s", from); 338 return(-1); 339 } 340 } else if (unlink(from) < 0) { 341 if (!ign) { 342 syswarn(1, errno, "Unable to remove %s", from); 343 return(-1); 344 } 345 return(1); 346 } 347 } 348 349 /* 350 * from file is gone (or did not exist), try to make the hard link. 351 * if it fails, check the path and try it again (if chk_path() says to 352 * try again) 353 */ 354 for (;;) { 355 if (link(to, from) == 0) 356 break; 357 oerrno = errno; 358 if (chk_path(from, to_sb->st_uid, to_sb->st_gid) == 0) 359 continue; 360 if (!ign) { 361 syswarn(1, oerrno, "Could not link to %s from %s", to, 362 from); 363 return(-1); 364 } 365 return(1); 366 } 367 368 /* 369 * all right the link was made 370 */ 371 return(0); 372 } 373 374 /* 375 * node_creat() 376 * create an entry in the file system (other than a file or hard link). 377 * If successful, sets uid/gid modes and times as required. 378 * Return: 379 * 0 if ok, -1 otherwise 380 */ 381 382 #if __STDC__ 383 int 384 node_creat(register ARCHD *arcn) 385 #else 386 int 387 node_creat(arcn) 388 register ARCHD *arcn; 389 #endif 390 { 391 register int res; 392 register int ign = 0; 393 register int oerrno; 394 register int pass = 0; 395 mode_t file_mode; 396 struct stat sb; 397 398 /* 399 * create node based on type, if that fails try to unlink the node and 400 * try again. finally check the path and try again. As noted in the 401 * file and link creation routines, this method seems to exhibit the 402 * best performance in general use workloads. 403 */ 404 file_mode = arcn->sb.st_mode & FILEBITS; 405 406 for (;;) { 407 switch(arcn->type) { 408 case PAX_DIR: 409 res = mkdir(arcn->name, file_mode); 410 if (ign) 411 res = 0; 412 break; 413 case PAX_CHR: 414 file_mode |= S_IFCHR; 415 res = mknod(arcn->name, file_mode, arcn->sb.st_rdev); 416 break; 417 case PAX_BLK: 418 file_mode |= S_IFBLK; 419 res = mknod(arcn->name, file_mode, arcn->sb.st_rdev); 420 break; 421 case PAX_FIF: 422 res = mkfifo(arcn->name, file_mode); 423 break; 424 case PAX_SCK: 425 /* 426 * Skip sockets, operation has no meaning under BSD 427 */ 428 warn(0, 429 "%s skipped. Sockets cannot be copied or extracted", 430 arcn->name); 431 return(-1); 432 case PAX_SLK: 433 if ((res = symlink(arcn->ln_name, arcn->name)) == 0) 434 return(0); 435 break; 436 case PAX_CTG: 437 case PAX_HLK: 438 case PAX_HRG: 439 case PAX_REG: 440 default: 441 /* 442 * we should never get here 443 */ 444 warn(0, "%s has an unknown file type, skipping", 445 arcn->name); 446 return(-1); 447 } 448 449 /* 450 * if we were able to create the node break out of the loop, 451 * otherwise try to unlink the node and try again. if that 452 * fails check the full path and try a final time. 453 */ 454 if (res == 0) 455 break; 456 457 /* 458 * we failed to make the node 459 */ 460 oerrno = errno; 461 if ((ign = unlnk_exist(arcn->name, arcn->type)) < 0) 462 return(-1); 463 464 if (++pass <= 1) 465 continue; 466 467 if (chk_path(arcn->name,arcn->sb.st_uid,arcn->sb.st_gid) < 0) { 468 syswarn(1, oerrno, "Could not create: %s", arcn->name); 469 return(-1); 470 } 471 } 472 473 /* 474 * we were able to create the node. set uid/gid, modes and times 475 */ 476 if (pids) 477 res = set_ids(arcn->name, arcn->sb.st_uid, arcn->sb.st_gid); 478 else 479 res = 0; 480 481 /* 482 * IMPORTANT SECURITY NOTE: 483 * if not preserving mode or we cannot set uid/gid, then PROHIBIT any 484 * set uid/gid bits 485 */ 486 if (!pmode || res) 487 arcn->sb.st_mode &= ~(SETBITS); 488 if (pmode) 489 set_pmode(arcn->name, arcn->sb.st_mode); 490 491 if (arcn->type == PAX_DIR) { 492 /* 493 * Dirs must be processed again at end of extract to set times 494 * and modes to agree with those stored in the archive. However 495 * to allow extract to continue, we may have to also set owner 496 * rights. This allows nodes in the archive that are children 497 * of this directory to be extracted without failure. Both time 498 * and modes will be fixed after the entire archive is read and 499 * before pax exits. 500 */ 501 if (access(arcn->name, R_OK | W_OK | X_OK) < 0) { 502 if (lstat(arcn->name, &sb) < 0) { 503 syswarn(0, errno,"Could not access %s (stat)", 504 arcn->name); 505 set_pmode(arcn->name,file_mode | S_IRWXU); 506 } else { 507 /* 508 * We have to add rights to the dir, so we make 509 * sure to restore the mode. The mode must be 510 * restored AS CREATED and not as stored if 511 * pmode is not set. 512 */ 513 set_pmode(arcn->name, 514 ((sb.st_mode & FILEBITS) | S_IRWXU)); 515 if (!pmode) 516 arcn->sb.st_mode = sb.st_mode; 517 } 518 519 /* 520 * we have to force the mode to what was set here, 521 * since we changed it from the default as created. 522 */ 523 add_dir(arcn->name, arcn->nlen, &(arcn->sb), 1); 524 } else if (pmode || patime || pmtime) 525 add_dir(arcn->name, arcn->nlen, &(arcn->sb), 0); 526 } 527 528 if (patime || pmtime) 529 set_ftime(arcn->name, arcn->sb.st_mtime, arcn->sb.st_atime, 0); 530 return(0); 531 } 532 533 /* 534 * unlnk_exist() 535 * Remove node from file system with the specified name. We pass the type 536 * of the node that is going to replace it. When we try to create a 537 * directory and find that it already exists, we allow processing to 538 * continue as proper modes etc will always be set for it later on. 539 * Return: 540 * 0 is ok to proceed, no file with the specified name exists 541 * -1 we were unable to remove the node, or we should not remove it (-k) 542 * 1 we found a directory and we were going to create a directory. 543 */ 544 545 #if __STDC__ 546 int 547 unlnk_exist(register char *name, register int type) 548 #else 549 int 550 unlnk_exist(name, type) 551 register char *name; 552 register int type; 553 #endif 554 { 555 struct stat sb; 556 557 /* 558 * the file does not exist, or -k we are done 559 */ 560 if (lstat(name, &sb) < 0) 561 return(0); 562 if (kflag) 563 return(-1); 564 565 if (S_ISDIR(sb.st_mode)) { 566 /* 567 * try to remove a directory, if it fails and we were going to 568 * create a directory anyway, tell the caller (return a 1) 569 */ 570 if (rmdir(name) < 0) { 571 if (type == PAX_DIR) 572 return(1); 573 syswarn(1,errno,"Unable to remove directory %s", name); 574 return(-1); 575 } 576 return(0); 577 } 578 579 /* 580 * try to get rid of all non-directory type nodes 581 */ 582 if (unlink(name) < 0) { 583 syswarn(1, errno, "Could not unlink %s", name); 584 return(-1); 585 } 586 return(0); 587 } 588 589 /* 590 * chk_path() 591 * We were trying to create some kind of node in the file system and it 592 * failed. chk_path() makes sure the path up to the node exists and is 593 * writeable. When we have to create a directory that is missing along the 594 * path somewhere, the directory we create will be set to the same 595 * uid/gid as the file has (when uid and gid are being preserved). 596 * NOTE: this routine is a real performance loss. It is only used as a 597 * last resort when trying to create entries in the file system. 598 * Return: 599 * -1 when it could find nothing it is allowed to fix. 600 * 0 otherwise 601 */ 602 603 #if __STDC__ 604 int 605 chk_path( register char *name, uid_t st_uid, gid_t st_gid) 606 #else 607 int 608 chk_path(name, st_uid, st_gid) 609 register char *name; 610 uid_t st_uid; 611 gid_t st_gid; 612 #endif 613 { 614 register char *spt = name; 615 struct stat sb; 616 int retval = -1; 617 618 /* 619 * watch out for paths with nodes stored directly in / (e.g. /bozo) 620 */ 621 if (*spt == '/') 622 ++spt; 623 624 for(;;) { 625 /* 626 * work foward from the first / and check each part of the path 627 */ 628 spt = strchr(spt, '/'); 629 if (spt == NULL) 630 break; 631 *spt = '\0'; 632 633 /* 634 * if it exists we assume it is a directory, it is not within 635 * the spec (at least it seems to read that way) to alter the 636 * file system for nodes NOT EXPLICITLY stored on the archive. 637 * If that assumption is changed, you would test the node here 638 * and figure out how to get rid of it (probably like some 639 * recursive unlink()) or fix up the directory permissions if 640 * required (do an access()). 641 */ 642 if (lstat(name, &sb) == 0) { 643 *(spt++) = '/'; 644 continue; 645 } 646 647 /* 648 * the path fails at this point, see if we can create the 649 * needed directory and continue on 650 */ 651 if (mkdir(name, S_IRWXU | S_IRWXG | S_IRWXO) < 0) { 652 *spt = '/'; 653 retval = -1; 654 break; 655 } 656 657 /* 658 * we were able to create the directory. We will tell the 659 * caller that we found something to fix, and it is ok to try 660 * and create the node again. 661 */ 662 retval = 0; 663 if (pids) 664 (void)set_ids(name, st_uid, st_gid); 665 666 /* 667 * make sure the user doen't have some strange umask that 668 * causes this newly created directory to be unusable. We fix 669 * the modes and restore them back to the creation default at 670 * the end of pax 671 */ 672 if ((access(name, R_OK | W_OK | X_OK) < 0) && 673 (lstat(name, &sb) == 0)) { 674 set_pmode(name, ((sb.st_mode & FILEBITS) | S_IRWXU)); 675 add_dir(name, spt - name, &sb, 1); 676 } 677 *(spt++) = '/'; 678 continue; 679 } 680 return(retval); 681 } 682 683 /* 684 * set_ftime() 685 * Set the access time and modification time for a named file. If frc is 686 * non-zero we force these times to be set even if the the user did not 687 * request access and/or modification time preservation (this is also 688 * used by -t to reset access times). 689 * When ign is zero, only those times the user has asked for are set, the 690 * other ones are left alone. We do not assume the un-documented feature 691 * of many utimes() implementations that consider a 0 time value as a do 692 * not set request. 693 */ 694 695 #if __STDC__ 696 void 697 set_ftime(char *fnm, time_t mtime, time_t atime, int frc) 698 #else 699 void 700 set_ftime(fnm, mtime, atime, frc) 701 char *fnm; 702 time_t mtime; 703 time_t atime; 704 int frc; 705 #endif 706 { 707 static struct timeval tv[2] = {{0L, 0L}, {0L, 0L}}; 708 struct stat sb; 709 710 tv[0].tv_sec = (long)atime; 711 tv[1].tv_sec = (long)mtime; 712 if (!frc && (!patime || !pmtime)) { 713 /* 714 * if we are not forcing, only set those times the user wants 715 * set. We get the current values of the times if we need them. 716 */ 717 if (lstat(fnm, &sb) == 0) { 718 if (!patime) 719 tv[0].tv_sec = (long)sb.st_atime; 720 if (!pmtime) 721 tv[1].tv_sec = (long)sb.st_mtime; 722 } else 723 syswarn(0,errno,"Unable to obtain file stats %s", fnm); 724 } 725 726 /* 727 * set the times 728 */ 729 if (utimes(fnm, tv) < 0) 730 syswarn(1, errno, "Access/modification time set failed on: %s", 731 fnm); 732 return; 733 } 734 735 /* 736 * set_ids() 737 * set the uid and gid of a file system node 738 * Return: 739 * 0 when set, -1 on failure 740 */ 741 742 #if __STDC__ 743 int 744 set_ids(char *fnm, uid_t uid, gid_t gid) 745 #else 746 int 747 set_ids(fnm, uid, gid) 748 char *fnm; 749 uid_t uid; 750 gid_t gid; 751 #endif 752 { 753 if (chown(fnm, uid, gid) < 0) { 754 syswarn(1, errno, "Unable to set file uid/gid of %s", fnm); 755 return(-1); 756 } 757 return(0); 758 } 759 760 /* 761 * set_pmode() 762 * Set file access mode 763 */ 764 765 #if __STDC__ 766 void 767 set_pmode(char *fnm, mode_t mode) 768 #else 769 void 770 set_pmode(fnm, mode) 771 char *fnm; 772 mode_t mode; 773 #endif 774 { 775 mode &= ABITS; 776 if (chmod(fnm, mode) < 0) 777 syswarn(1, errno, "Could not set permissions on %s", fnm); 778 return; 779 } 780 781 /* 782 * file_write() 783 * Write/copy a file (during copy or archive extract). This routine knows 784 * how to copy files with lseek holes in it. (Which are read as file 785 * blocks containing all 0's but do not have any file blocks associated 786 * with the data). Typical examples of these are files created by dbm 787 * variants (.pag files). While the file size of these files are huge, the 788 * actual storage is quite small (the files are sparse). The problem is 789 * the holes read as all zeros so are probably stored on the archive that 790 * way (there is no way to determine if the file block is really a hole, 791 * we only know that a file block of all zero's can be a hole). 792 * At this writing, no major archive format knows how to archive files 793 * with holes. However, on extraction (or during copy, -rw) we have to 794 * deal with these files. Without detecting the holes, the files can 795 * consume a lot of file space if just written to disk. This replacement 796 * for write when passed the basic allocation size of a file system block, 797 * uses lseek whenever it detects the input data is all 0 within that 798 * file block. In more detail, the strategy is as follows: 799 * While the input is all zero keep doing an lseek. Keep track of when we 800 * pass over file block boundries. Only write when we hit a non zero 801 * input. once we have written a file block, we continue to write it to 802 * the end (we stop looking at the input). When we reach the start of the 803 * next file block, start checking for zero blocks again. Working on file 804 * block boundries significantly reduces the overhead when copying files 805 * that are NOT very sparse. This overhead (when compared to a write) is 806 * almost below the measurement resolution on many systems. Without it, 807 * files with holes cannot be safely copied. It does has a side effect as 808 * it can put holes into files that did not have them before, but that is 809 * not a problem since the file contents are unchanged (in fact it saves 810 * file space). (Except on paging files for diskless clients. But since we 811 * cannot determine one of those file from here, we ignore them). If this 812 * ever ends up on a system where CTG files are supported and the holes 813 * are not desired, just do a conditional test in those routines that 814 * call file_write() and have it call write() instead. BEFORE CLOSING THE 815 * FILE, make sure to call file_flush() when the last write finishes with 816 * an empty block. A lot of file systems will not create an lseek hole at 817 * the end. In this case we drop a single 0 at the end to force the 818 * trailing 0's in the file. 819 * ---Parameters--- 820 * rem: how many bytes left in this file system block 821 * isempt: have we written to the file block yet (is it empty) 822 * sz: basic file block allocation size 823 * cnt: number of bytes on this write 824 * str: buffer to write 825 * Return: 826 * number of bytes written, -1 on write (or lseek) error. 827 */ 828 829 #if __STDC__ 830 int 831 file_write(int fd, char *str, register int cnt, int *rem, int *isempt, int sz, 832 char *name) 833 #else 834 int 835 file_write(fd, str, cnt, rem, isempt, sz, name) 836 int fd; 837 char *str; 838 register int cnt; 839 int *rem; 840 int *isempt; 841 int sz; 842 char *name; 843 #endif 844 { 845 register char *pt; 846 register char *end; 847 register int wcnt; 848 register char *st = str; 849 850 /* 851 * while we have data to process 852 */ 853 while (cnt) { 854 if (!*rem) { 855 /* 856 * We are now at the start of file system block again 857 * (or what we think one is...). start looking for 858 * empty blocks again 859 */ 860 *isempt = 1; 861 *rem = sz; 862 } 863 864 /* 865 * only examine up to the end of the current file block or 866 * remaining characters to write, whatever is smaller 867 */ 868 wcnt = MIN(cnt, *rem); 869 cnt -= wcnt; 870 *rem -= wcnt; 871 if (*isempt) { 872 /* 873 * have not written to this block yet, so we keep 874 * looking for zero's 875 */ 876 pt = st; 877 end = st + wcnt; 878 879 /* 880 * look for a zero filled buffer 881 */ 882 while ((pt < end) && (*pt == '\0')) 883 ++pt; 884 885 if (pt == end) { 886 /* 887 * skip, buf is empty so far 888 */ 889 if (lseek(fd, (off_t)wcnt, SEEK_CUR) < 0) { 890 syswarn(1,errno,"File seek on %s", 891 name); 892 return(-1); 893 } 894 st = pt; 895 continue; 896 } 897 /* 898 * drat, the buf is not zero filled 899 */ 900 *isempt = 0; 901 } 902 903 /* 904 * have non-zero data in this file system block, have to write 905 */ 906 if (write(fd, st, wcnt) != wcnt) { 907 syswarn(1, errno, "Failed write to file %s", name); 908 return(-1); 909 } 910 st += wcnt; 911 } 912 return(st - str); 913 } 914 915 /* 916 * file_flush() 917 * when the last file block in a file is zero, many file systems will not 918 * let us create a hole at the end. To get the last block with zeros, we 919 * write the last BYTE with a zero (back up one byte and write a zero). 920 */ 921 922 #if __STDC__ 923 void 924 file_flush(int fd, char *fname, int isempt) 925 #else 926 void 927 file_flush(fd, fname, isempt) 928 int fd; 929 char *fname; 930 int isempt; 931 #endif 932 { 933 static char blnk[] = "\0"; 934 935 /* 936 * silly test, but make sure we are only called when the last block is 937 * filled with all zeros. 938 */ 939 if (!isempt) 940 return; 941 942 /* 943 * move back one byte and write a zero 944 */ 945 if (lseek(fd, (off_t)-1, SEEK_CUR) < 0) { 946 syswarn(1, errno, "Failed seek on file %s", fname); 947 return; 948 } 949 950 if (write(fd, blnk, 1) < 0) 951 syswarn(1, errno, "Failed write to file %s", fname); 952 return; 953 } 954 955 /* 956 * rdfile_close() 957 * close a file we have beed reading (to copy or archive). If we have to 958 * reset access time (tflag) do so (the times are stored in arcn). 959 */ 960 961 #if __STDC__ 962 void 963 rdfile_close(register ARCHD *arcn, register int *fd) 964 #else 965 void 966 rdfile_close(arcn, fd) 967 register ARCHD *arcn; 968 register int *fd; 969 #endif 970 { 971 /* 972 * make sure the file is open 973 */ 974 if (*fd < 0) 975 return; 976 977 (void)close(*fd); 978 *fd = -1; 979 if (!tflag) 980 return; 981 982 /* 983 * user wants last access time reset 984 */ 985 set_ftime(arcn->org_name, arcn->sb.st_mtime, arcn->sb.st_atime, 1); 986 return; 987 } 988 989 /* 990 * set_crc() 991 * read a file to calculate its crc. This is a real drag. Archive formats 992 * that have this, end up reading the file twice (we have to write the 993 * header WITH the crc before writing the file contents. Oh well... 994 * Return: 995 * 0 if was able to calculate the crc, -1 otherwise 996 */ 997 998 #if __STDC__ 999 int 1000 set_crc(register ARCHD *arcn, register int fd) 1001 #else 1002 int 1003 set_crc(arcn, fd) 1004 register ARCHD *arcn; 1005 register int fd; 1006 #endif 1007 { 1008 register int i; 1009 register int res; 1010 off_t cpcnt = 0L; 1011 u_long size; 1012 unsigned long crc = 0L; 1013 char tbuf[FILEBLK]; 1014 struct stat sb; 1015 1016 if (fd < 0) { 1017 /* 1018 * hmm, no fd, should never happen. well no crc then. 1019 */ 1020 arcn->crc = 0L; 1021 return(0); 1022 } 1023 1024 if ((size = (u_long)arcn->sb.st_blksize) > (u_long)sizeof(tbuf)) 1025 size = (u_long)sizeof(tbuf); 1026 1027 /* 1028 * read all the bytes we think that there are in the file. If the user 1029 * is trying to archive an active file, forget this file. 1030 */ 1031 for(;;) { 1032 if ((res = read(fd, tbuf, size)) <= 0) 1033 break; 1034 cpcnt += res; 1035 for (i = 0; i < res; ++i) 1036 crc += (tbuf[i] & 0xff); 1037 } 1038 1039 /* 1040 * safety check. we want to avoid archiving files that are active as 1041 * they can create inconsistant archive copies. 1042 */ 1043 if (cpcnt != arcn->sb.st_size) 1044 warn(1, "File changed size %s", arcn->org_name); 1045 else if (fstat(fd, &sb) < 0) 1046 syswarn(1, errno, "Failed stat on %s", arcn->org_name); 1047 else if (arcn->sb.st_mtime != sb.st_mtime) 1048 warn(1, "File %s was modified during read", arcn->org_name); 1049 else if (lseek(fd, (off_t)0L, SEEK_SET) < 0) 1050 syswarn(1, errno, "File rewind failed on: %s", arcn->org_name); 1051 else { 1052 arcn->crc = crc; 1053 return(0); 1054 } 1055 return(-1); 1056 } 1057