file_subs.c revision 1.4
1/* $NetBSD: file_subs.c,v 1.4 1995/03/21 09:07:18 cgd Exp $ */ 2 3/*- 4 * Copyright (c) 1992 Keith Muller. 5 * Copyright (c) 1992, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * Keith Muller of the University of California, San Diego. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40#ifndef lint 41#if 0 42static char sccsid[] = "@(#)file_subs.c 8.1 (Berkeley) 5/31/93"; 43#else 44static char rcsid[] = "$NetBSD: file_subs.c,v 1.4 1995/03/21 09:07:18 cgd Exp $"; 45#endif 46#endif /* not lint */ 47 48#include <sys/types.h> 49#include <sys/time.h> 50#include <sys/stat.h> 51#include <unistd.h> 52#include <sys/param.h> 53#include <fcntl.h> 54#include <string.h> 55#include <stdio.h> 56#include <ctype.h> 57#include <errno.h> 58#include <sys/uio.h> 59#include <stdlib.h> 60#include "pax.h" 61#include "extern.h" 62 63static int 64mk_link __P((register char *,register struct stat *,register char *, int)); 65 66/* 67 * routines that deal with file operations such as: creating, removing; 68 * and setting access modes, uid/gid and times of files 69 */ 70 71#define FILEBITS (S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO) 72#define SETBITS (S_ISUID | S_ISGID) 73#define ABITS (FILEBITS | SETBITS) 74 75/* 76 * file_creat() 77 * Create and open a file. 78 * Return: 79 * file descriptor or -1 for failure 80 */ 81 82#if __STDC__ 83int 84file_creat(register ARCHD *arcn) 85#else 86int 87file_creat(arcn) 88 register ARCHD *arcn; 89#endif 90{ 91 int fd = -1; 92 mode_t file_mode; 93 int oerrno; 94 95 /* 96 * assume file doesn't exist, so just try to create it, most times this 97 * works. We have to take special handling when the file does exist. To 98 * detect this, we use O_EXCL. For example when trying to create a 99 * file and a character device or fifo exists with the same name, we 100 * can accidently open the device by mistake (or block waiting to open) 101 * If we find that the open has failed, then figure spend the effore to 102 * figure out why. This strategy was found to have better average 103 * performance in common use than checking the file (and the path) 104 * first with lstat. 105 */ 106 file_mode = arcn->sb.st_mode & FILEBITS; 107 if ((fd = open(arcn->name, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 108 file_mode)) >= 0) 109 return(fd); 110 111 /* 112 * the file seems to exist. First we try to get rid of it (found to be 113 * the second most common failure when traced). If this fails, only 114 * then we go to the expense to check and create the path to the file 115 */ 116 if (unlnk_exist(arcn->name, arcn->type) != 0) 117 return(-1); 118 119 for (;;) { 120 /* 121 * try to open it again, if this fails, check all the nodes in 122 * the path and give it a final try. if chk_path() finds that 123 * it cannot fix anything, we will skip the last attempt 124 */ 125 if ((fd = open(arcn->name, O_WRONLY | O_CREAT | O_TRUNC, 126 file_mode)) >= 0) 127 break; 128 oerrno = errno; 129 if (chk_path(arcn->name,arcn->sb.st_uid,arcn->sb.st_gid) < 0) { 130 syswarn(1, oerrno, "Unable to create %s", arcn->name); 131 return(-1); 132 } 133 } 134 return(fd); 135} 136 137/* 138 * file_close() 139 * Close file descriptor to a file just created by pax. Sets modes, 140 * ownership and times as required. 141 * Return: 142 * 0 for success, -1 for failure 143 */ 144 145#if __STDC__ 146void 147file_close(register ARCHD *arcn, int fd) 148#else 149void 150file_close(arcn, fd) 151 register ARCHD *arcn; 152 int fd; 153#endif 154{ 155 int res = 0; 156 157 if (fd < 0) 158 return; 159 if (close(fd) < 0) 160 syswarn(0, errno, "Unable to close file descriptor on %s", 161 arcn->name); 162 163 /* 164 * set owner/groups first as this may strip off mode bits we want 165 * then set file permission modes. Then set file access and 166 * modification times. 167 */ 168 if (pids) 169 res = set_ids(arcn->name, arcn->sb.st_uid, arcn->sb.st_gid); 170 171 /* 172 * IMPORTANT SECURITY NOTE: 173 * if not preserving mode or we cannot set uid/gid, then PROHIBIT 174 * set uid/gid bits 175 */ 176 if (!pmode || res) 177 arcn->sb.st_mode &= ~(SETBITS); 178 if (pmode) 179 set_pmode(arcn->name, arcn->sb.st_mode); 180 if (patime || pmtime) 181 set_ftime(arcn->name, arcn->sb.st_mtime, arcn->sb.st_atime, 0); 182} 183 184/* 185 * lnk_creat() 186 * Create a hard link to arcn->ln_name from arcn->name. arcn->ln_name 187 * must exist; 188 * Return: 189 * 0 if ok, -1 otherwise 190 */ 191 192#if __STDC__ 193int 194lnk_creat(register ARCHD *arcn) 195#else 196int 197lnk_creat(arcn) 198 register ARCHD *arcn; 199#endif 200{ 201 struct stat sb; 202 203 /* 204 * we may be running as root, so we have to be sure that link target 205 * is not a directory, so we lstat and check 206 */ 207 if (lstat(arcn->ln_name, &sb) < 0) { 208 syswarn(1,errno,"Unable to link to %s from %s", arcn->ln_name, 209 arcn->name); 210 return(-1); 211 } 212 213 if (S_ISDIR(sb.st_mode)) { 214 warn(1, "A hard link to the directory %s is not allowed", 215 arcn->ln_name); 216 return(-1); 217 } 218 219 return(mk_link(arcn->ln_name, &sb, arcn->name, 0)); 220} 221 222/* 223 * cross_lnk() 224 * Create a hard link to arcn->org_name from arcn->name. Only used in copy 225 * with the -l flag. No warning or error if this does not succeed (we will 226 * then just create the file) 227 * Return: 228 * 1 if copy() should try to create this file node 229 * 0 if cross_lnk() ok, -1 for fatal flaw (like linking to self). 230 */ 231 232#if __STDC__ 233int 234cross_lnk(register ARCHD *arcn) 235#else 236int 237cross_lnk(arcn) 238 register ARCHD *arcn; 239#endif 240{ 241 /* 242 * try to make a link to orginal file (-l flag in copy mode). make sure 243 * we do not try to link to directories in case we are running as root 244 * (and it might succeed). 245 */ 246 if (arcn->type == PAX_DIR) 247 return(1); 248 return(mk_link(arcn->org_name, &(arcn->sb), arcn->name, 1)); 249} 250 251/* 252 * chk_same() 253 * In copy mode if we are not trying to make hard links between the src 254 * and destinations, make sure we are not going to overwrite ourselves by 255 * accident. This slows things down a little, but we have to protect all 256 * those people who make typing errors. 257 * Return: 258 * 1 the target does not exist, go ahead and copy 259 * 0 skip it file exists (-k) or may be the same as source file 260 */ 261 262#if __STDC__ 263int 264chk_same(register ARCHD *arcn) 265#else 266int 267chk_same(arcn) 268 register ARCHD *arcn; 269#endif 270{ 271 struct stat sb; 272 273 /* 274 * if file does not exist, return. if file exists and -k, skip it 275 * quietly 276 */ 277 if (lstat(arcn->name, &sb) < 0) 278 return(1); 279 if (kflag) 280 return(0); 281 282 /* 283 * better make sure the user does not have src == dest by mistake 284 */ 285 if ((arcn->sb.st_dev == sb.st_dev) && (arcn->sb.st_ino == sb.st_ino)) { 286 warn(1, "Unable to copy %s, file would overwrite itself", 287 arcn->name); 288 return(0); 289 } 290 return(1); 291} 292 293/* 294 * mk_link() 295 * try to make a hard link between two files. if ign set, we do not 296 * complain. 297 * Return: 298 * 0 if successful (or we are done with this file but no error, such as 299 * finding the from file exists and the user has set -k). 300 * 1 when ign was set to indicates we could not make the link but we 301 * should try to copy/extract the file as that might work (and is an 302 * allowed option). -1 an error occurred. 303 */ 304 305#if __STDC__ 306static int 307mk_link(register char *to, register struct stat *to_sb, register char *from, 308 int ign) 309#else 310static int 311mk_link(to, to_sb, from, ign) 312 register char *to; 313 register struct stat *to_sb; 314 register char *from; 315 int ign; 316#endif 317{ 318 struct stat sb; 319 int oerrno; 320 321 /* 322 * if from file exists, it has to be unlinked to make the link. If the 323 * file exists and -k is set, skip it quietly 324 */ 325 if (lstat(from, &sb) == 0) { 326 if (kflag) 327 return(0); 328 329 /* 330 * make sure it is not the same file, protect the user 331 */ 332 if ((to_sb->st_dev==sb.st_dev)&&(to_sb->st_ino == sb.st_ino)) { 333 warn(1, "Unable to link file %s to itself", to); 334 return(-1);; 335 } 336 337 /* 338 * try to get rid of the file, based on the type 339 */ 340 if (S_ISDIR(sb.st_mode)) { 341 if (rmdir(from) < 0) { 342 syswarn(1, errno, "Unable to remove %s", from); 343 return(-1); 344 } 345 } else if (unlink(from) < 0) { 346 if (!ign) { 347 syswarn(1, errno, "Unable to remove %s", from); 348 return(-1); 349 } 350 return(1); 351 } 352 } 353 354 /* 355 * from file is gone (or did not exist), try to make the hard link. 356 * if it fails, check the path and try it again (if chk_path() says to 357 * try again) 358 */ 359 for (;;) { 360 if (link(to, from) == 0) 361 break; 362 oerrno = errno; 363 if (chk_path(from, to_sb->st_uid, to_sb->st_gid) == 0) 364 continue; 365 if (!ign) { 366 syswarn(1, oerrno, "Could not link to %s from %s", to, 367 from); 368 return(-1); 369 } 370 return(1); 371 } 372 373 /* 374 * all right the link was made 375 */ 376 return(0); 377} 378 379/* 380 * node_creat() 381 * create an entry in the file system (other than a file or hard link). 382 * If successful, sets uid/gid modes and times as required. 383 * Return: 384 * 0 if ok, -1 otherwise 385 */ 386 387#if __STDC__ 388int 389node_creat(register ARCHD *arcn) 390#else 391int 392node_creat(arcn) 393 register ARCHD *arcn; 394#endif 395{ 396 register int res; 397 register int ign = 0; 398 register int oerrno; 399 register int pass = 0; 400 mode_t file_mode; 401 struct stat sb; 402 403 /* 404 * create node based on type, if that fails try to unlink the node and 405 * try again. finally check the path and try again. As noted in the 406 * file and link creation routines, this method seems to exhibit the 407 * best performance in general use workloads. 408 */ 409 file_mode = arcn->sb.st_mode & FILEBITS; 410 411 for (;;) { 412 switch(arcn->type) { 413 case PAX_DIR: 414 res = mkdir(arcn->name, file_mode); 415 if (ign) 416 res = 0; 417 break; 418 case PAX_CHR: 419 file_mode |= S_IFCHR; 420 res = mknod(arcn->name, file_mode, arcn->sb.st_rdev); 421 break; 422 case PAX_BLK: 423 file_mode |= S_IFBLK; 424 res = mknod(arcn->name, file_mode, arcn->sb.st_rdev); 425 break; 426 case PAX_FIF: 427 res = mkfifo(arcn->name, file_mode); 428 break; 429 case PAX_SCK: 430 /* 431 * Skip sockets, operation has no meaning under BSD 432 */ 433 warn(0, 434 "%s skipped. Sockets cannot be copied or extracted", 435 arcn->name); 436 return(-1); 437 case PAX_SLK: 438 if ((res = symlink(arcn->ln_name, arcn->name)) == 0) 439 return(0); 440 break; 441 case PAX_CTG: 442 case PAX_HLK: 443 case PAX_HRG: 444 case PAX_REG: 445 default: 446 /* 447 * we should never get here 448 */ 449 warn(0, "%s has an unknown file type, skipping", 450 arcn->name); 451 return(-1); 452 } 453 454 /* 455 * if we were able to create the node break out of the loop, 456 * otherwise try to unlink the node and try again. if that 457 * fails check the full path and try a final time. 458 */ 459 if (res == 0) 460 break; 461 462 /* 463 * we failed to make the node 464 */ 465 oerrno = errno; 466 if ((ign = unlnk_exist(arcn->name, arcn->type)) < 0) 467 return(-1); 468 469 if (++pass <= 1) 470 continue; 471 472 if (chk_path(arcn->name,arcn->sb.st_uid,arcn->sb.st_gid) < 0) { 473 syswarn(1, oerrno, "Could not create: %s", arcn->name); 474 return(-1); 475 } 476 } 477 478 /* 479 * we were able to create the node. set uid/gid, modes and times 480 */ 481 if (pids) 482 res = set_ids(arcn->name, arcn->sb.st_uid, arcn->sb.st_gid); 483 else 484 res = 0; 485 486 /* 487 * IMPORTANT SECURITY NOTE: 488 * if not preserving mode or we cannot set uid/gid, then PROHIBIT any 489 * set uid/gid bits 490 */ 491 if (!pmode || res) 492 arcn->sb.st_mode &= ~(SETBITS); 493 if (pmode) 494 set_pmode(arcn->name, arcn->sb.st_mode); 495 496 if (arcn->type == PAX_DIR) { 497 /* 498 * Dirs must be processed again at end of extract to set times 499 * and modes to agree with those stored in the archive. However 500 * to allow extract to continue, we may have to also set owner 501 * rights. This allows nodes in the archive that are children 502 * of this directory to be extracted without failure. Both time 503 * and modes will be fixed after the entire archive is read and 504 * before pax exits. 505 */ 506 if (access(arcn->name, R_OK | W_OK | X_OK) < 0) { 507 if (lstat(arcn->name, &sb) < 0) { 508 syswarn(0, errno,"Could not access %s (stat)", 509 arcn->name); 510 set_pmode(arcn->name,file_mode | S_IRWXU); 511 } else { 512 /* 513 * We have to add rights to the dir, so we make 514 * sure to restore the mode. The mode must be 515 * restored AS CREATED and not as stored if 516 * pmode is not set. 517 */ 518 set_pmode(arcn->name, 519 ((sb.st_mode & FILEBITS) | S_IRWXU)); 520 if (!pmode) 521 arcn->sb.st_mode = sb.st_mode; 522 } 523 524 /* 525 * we have to force the mode to what was set here, 526 * since we changed it from the default as created. 527 */ 528 add_dir(arcn->name, arcn->nlen, &(arcn->sb), 1); 529 } else if (pmode || patime || pmtime) 530 add_dir(arcn->name, arcn->nlen, &(arcn->sb), 0); 531 } 532 533 if (patime || pmtime) 534 set_ftime(arcn->name, arcn->sb.st_mtime, arcn->sb.st_atime, 0); 535 return(0); 536} 537 538/* 539 * unlnk_exist() 540 * Remove node from file system with the specified name. We pass the type 541 * of the node that is going to replace it. When we try to create a 542 * directory and find that it already exists, we allow processing to 543 * continue as proper modes etc will always be set for it later on. 544 * Return: 545 * 0 is ok to proceed, no file with the specified name exists 546 * -1 we were unable to remove the node, or we should not remove it (-k) 547 * 1 we found a directory and we were going to create a directory. 548 */ 549 550#if __STDC__ 551int 552unlnk_exist(register char *name, register int type) 553#else 554int 555unlnk_exist(name, type) 556 register char *name; 557 register int type; 558#endif 559{ 560 struct stat sb; 561 562 /* 563 * the file does not exist, or -k we are done 564 */ 565 if (lstat(name, &sb) < 0) 566 return(0); 567 if (kflag) 568 return(-1); 569 570 if (S_ISDIR(sb.st_mode)) { 571 /* 572 * try to remove a directory, if it fails and we were going to 573 * create a directory anyway, tell the caller (return a 1) 574 */ 575 if (rmdir(name) < 0) { 576 if (type == PAX_DIR) 577 return(1); 578 syswarn(1,errno,"Unable to remove directory %s", name); 579 return(-1); 580 } 581 return(0); 582 } 583 584 /* 585 * try to get rid of all non-directory type nodes 586 */ 587 if (unlink(name) < 0) { 588 syswarn(1, errno, "Could not unlink %s", name); 589 return(-1); 590 } 591 return(0); 592} 593 594/* 595 * chk_path() 596 * We were trying to create some kind of node in the file system and it 597 * failed. chk_path() makes sure the path up to the node exists and is 598 * writeable. When we have to create a directory that is missing along the 599 * path somewhere, the directory we create will be set to the same 600 * uid/gid as the file has (when uid and gid are being preserved). 601 * NOTE: this routine is a real performance loss. It is only used as a 602 * last resort when trying to create entries in the file system. 603 * Return: 604 * -1 when it could find nothing it is allowed to fix. 605 * 0 otherwise 606 */ 607 608#if __STDC__ 609int 610chk_path( register char *name, uid_t st_uid, gid_t st_gid) 611#else 612int 613chk_path(name, st_uid, st_gid) 614 register char *name; 615 uid_t st_uid; 616 gid_t st_gid; 617#endif 618{ 619 register char *spt = name; 620 struct stat sb; 621 int retval = -1; 622 623 /* 624 * watch out for paths with nodes stored directly in / (e.g. /bozo) 625 */ 626 if (*spt == '/') 627 ++spt; 628 629 for(;;) { 630 /* 631 * work foward from the first / and check each part of the path 632 */ 633 spt = strchr(spt, '/'); 634 if (spt == NULL) 635 break; 636 *spt = '\0'; 637 638 /* 639 * if it exists we assume it is a directory, it is not within 640 * the spec (at least it seems to read that way) to alter the 641 * file system for nodes NOT EXPLICITLY stored on the archive. 642 * If that assumption is changed, you would test the node here 643 * and figure out how to get rid of it (probably like some 644 * recursive unlink()) or fix up the directory permissions if 645 * required (do an access()). 646 */ 647 if (lstat(name, &sb) == 0) { 648 *(spt++) = '/'; 649 continue; 650 } 651 652 /* 653 * the path fails at this point, see if we can create the 654 * needed directory and continue on 655 */ 656 if (mkdir(name, S_IRWXU | S_IRWXG | S_IRWXO) < 0) { 657 *spt = '/'; 658 retval = -1; 659 break; 660 } 661 662 /* 663 * we were able to create the directory. We will tell the 664 * caller that we found something to fix, and it is ok to try 665 * and create the node again. 666 */ 667 retval = 0; 668 if (pids) 669 (void)set_ids(name, st_uid, st_gid); 670 671 /* 672 * make sure the user doen't have some strange umask that 673 * causes this newly created directory to be unusable. We fix 674 * the modes and restore them back to the creation default at 675 * the end of pax 676 */ 677 if ((access(name, R_OK | W_OK | X_OK) < 0) && 678 (lstat(name, &sb) == 0)) { 679 set_pmode(name, ((sb.st_mode & FILEBITS) | S_IRWXU)); 680 add_dir(name, spt - name, &sb, 1); 681 } 682 *(spt++) = '/'; 683 continue; 684 } 685 return(retval); 686} 687 688/* 689 * set_ftime() 690 * Set the access time and modification time for a named file. If frc is 691 * non-zero we force these times to be set even if the the user did not 692 * request access and/or modification time preservation (this is also 693 * used by -t to reset access times). 694 * When ign is zero, only those times the user has asked for are set, the 695 * other ones are left alone. We do not assume the un-documented feature 696 * of many utimes() implementations that consider a 0 time value as a do 697 * not set request. 698 */ 699 700#if __STDC__ 701void 702set_ftime(char *fnm, time_t mtime, time_t atime, int frc) 703#else 704void 705set_ftime(fnm, mtime, atime, frc) 706 char *fnm; 707 time_t mtime; 708 time_t atime; 709 int frc; 710#endif 711{ 712 static struct timeval tv[2] = {{0L, 0L}, {0L, 0L}}; 713 struct stat sb; 714 715 tv[0].tv_sec = (long)atime; 716 tv[1].tv_sec = (long)mtime; 717 if (!frc && (!patime || !pmtime)) { 718 /* 719 * if we are not forcing, only set those times the user wants 720 * set. We get the current values of the times if we need them. 721 */ 722 if (lstat(fnm, &sb) == 0) { 723 if (!patime) 724 tv[0].tv_sec = (long)sb.st_atime; 725 if (!pmtime) 726 tv[1].tv_sec = (long)sb.st_mtime; 727 } else 728 syswarn(0,errno,"Unable to obtain file stats %s", fnm); 729 } 730 731 /* 732 * set the times 733 */ 734 if (utimes(fnm, tv) < 0) 735 syswarn(1, errno, "Access/modification time set failed on: %s", 736 fnm); 737 return; 738} 739 740/* 741 * set_ids() 742 * set the uid and gid of a file system node 743 * Return: 744 * 0 when set, -1 on failure 745 */ 746 747#if __STDC__ 748int 749set_ids(char *fnm, uid_t uid, gid_t gid) 750#else 751int 752set_ids(fnm, uid, gid) 753 char *fnm; 754 uid_t uid; 755 gid_t gid; 756#endif 757{ 758 if (chown(fnm, uid, gid) < 0) { 759 syswarn(1, errno, "Unable to set file uid/gid of %s", fnm); 760 return(-1); 761 } 762 return(0); 763} 764 765/* 766 * set_pmode() 767 * Set file access mode 768 */ 769 770#if __STDC__ 771void 772set_pmode(char *fnm, mode_t mode) 773#else 774void 775set_pmode(fnm, mode) 776 char *fnm; 777 mode_t mode; 778#endif 779{ 780 mode &= ABITS; 781 if (chmod(fnm, mode) < 0) 782 syswarn(1, errno, "Could not set permissions on %s", fnm); 783 return; 784} 785 786/* 787 * file_write() 788 * Write/copy a file (during copy or archive extract). This routine knows 789 * how to copy files with lseek holes in it. (Which are read as file 790 * blocks containing all 0's but do not have any file blocks associated 791 * with the data). Typical examples of these are files created by dbm 792 * variants (.pag files). While the file size of these files are huge, the 793 * actual storage is quite small (the files are sparse). The problem is 794 * the holes read as all zeros so are probably stored on the archive that 795 * way (there is no way to determine if the file block is really a hole, 796 * we only know that a file block of all zero's can be a hole). 797 * At this writing, no major archive format knows how to archive files 798 * with holes. However, on extraction (or during copy, -rw) we have to 799 * deal with these files. Without detecting the holes, the files can 800 * consume a lot of file space if just written to disk. This replacement 801 * for write when passed the basic allocation size of a file system block, 802 * uses lseek whenever it detects the input data is all 0 within that 803 * file block. In more detail, the strategy is as follows: 804 * While the input is all zero keep doing an lseek. Keep track of when we 805 * pass over file block boundries. Only write when we hit a non zero 806 * input. once we have written a file block, we continue to write it to 807 * the end (we stop looking at the input). When we reach the start of the 808 * next file block, start checking for zero blocks again. Working on file 809 * block boundries significantly reduces the overhead when copying files 810 * that are NOT very sparse. This overhead (when compared to a write) is 811 * almost below the measurement resolution on many systems. Without it, 812 * files with holes cannot be safely copied. It does has a side effect as 813 * it can put holes into files that did not have them before, but that is 814 * not a problem since the file contents are unchanged (in fact it saves 815 * file space). (Except on paging files for diskless clients. But since we 816 * cannot determine one of those file from here, we ignore them). If this 817 * ever ends up on a system where CTG files are supported and the holes 818 * are not desired, just do a conditional test in those routines that 819 * call file_write() and have it call write() instead. BEFORE CLOSING THE 820 * FILE, make sure to call file_flush() when the last write finishes with 821 * an empty block. A lot of file systems will not create an lseek hole at 822 * the end. In this case we drop a single 0 at the end to force the 823 * trailing 0's in the file. 824 * ---Parameters--- 825 * rem: how many bytes left in this file system block 826 * isempt: have we written to the file block yet (is it empty) 827 * sz: basic file block allocation size 828 * cnt: number of bytes on this write 829 * str: buffer to write 830 * Return: 831 * number of bytes written, -1 on write (or lseek) error. 832 */ 833 834#if __STDC__ 835int 836file_write(int fd, char *str, register int cnt, int *rem, int *isempt, int sz, 837 char *name) 838#else 839int 840file_write(fd, str, cnt, rem, isempt, sz, name) 841 int fd; 842 char *str; 843 register int cnt; 844 int *rem; 845 int *isempt; 846 int sz; 847 char *name; 848#endif 849{ 850 register char *pt; 851 register char *end; 852 register int wcnt; 853 register char *st = str; 854 855 /* 856 * while we have data to process 857 */ 858 while (cnt) { 859 if (!*rem) { 860 /* 861 * We are now at the start of file system block again 862 * (or what we think one is...). start looking for 863 * empty blocks again 864 */ 865 *isempt = 1; 866 *rem = sz; 867 } 868 869 /* 870 * only examine up to the end of the current file block or 871 * remaining characters to write, whatever is smaller 872 */ 873 wcnt = MIN(cnt, *rem); 874 cnt -= wcnt; 875 *rem -= wcnt; 876 if (*isempt) { 877 /* 878 * have not written to this block yet, so we keep 879 * looking for zero's 880 */ 881 pt = st; 882 end = st + wcnt; 883 884 /* 885 * look for a zero filled buffer 886 */ 887 while ((pt < end) && (*pt == '\0')) 888 ++pt; 889 890 if (pt == end) { 891 /* 892 * skip, buf is empty so far 893 */ 894 if (lseek(fd, (off_t)wcnt, SEEK_CUR) < 0) { 895 syswarn(1,errno,"File seek on %s", 896 name); 897 return(-1); 898 } 899 st = pt; 900 continue; 901 } 902 /* 903 * drat, the buf is not zero filled 904 */ 905 *isempt = 0; 906 } 907 908 /* 909 * have non-zero data in this file system block, have to write 910 */ 911 if (write(fd, st, wcnt) != wcnt) { 912 syswarn(1, errno, "Failed write to file %s", name); 913 return(-1); 914 } 915 st += wcnt; 916 } 917 return(st - str); 918} 919 920/* 921 * file_flush() 922 * when the last file block in a file is zero, many file systems will not 923 * let us create a hole at the end. To get the last block with zeros, we 924 * write the last BYTE with a zero (back up one byte and write a zero). 925 */ 926 927#if __STDC__ 928void 929file_flush(int fd, char *fname, int isempt) 930#else 931void 932file_flush(fd, fname, isempt) 933 int fd; 934 char *fname; 935 int isempt; 936#endif 937{ 938 static char blnk[] = "\0"; 939 940 /* 941 * silly test, but make sure we are only called when the last block is 942 * filled with all zeros. 943 */ 944 if (!isempt) 945 return; 946 947 /* 948 * move back one byte and write a zero 949 */ 950 if (lseek(fd, (off_t)-1, SEEK_CUR) < 0) { 951 syswarn(1, errno, "Failed seek on file %s", fname); 952 return; 953 } 954 955 if (write(fd, blnk, 1) < 0) 956 syswarn(1, errno, "Failed write to file %s", fname); 957 return; 958} 959 960/* 961 * rdfile_close() 962 * close a file we have beed reading (to copy or archive). If we have to 963 * reset access time (tflag) do so (the times are stored in arcn). 964 */ 965 966#if __STDC__ 967void 968rdfile_close(register ARCHD *arcn, register int *fd) 969#else 970void 971rdfile_close(arcn, fd) 972 register ARCHD *arcn; 973 register int *fd; 974#endif 975{ 976 /* 977 * make sure the file is open 978 */ 979 if (*fd < 0) 980 return; 981 982 (void)close(*fd); 983 *fd = -1; 984 if (!tflag) 985 return; 986 987 /* 988 * user wants last access time reset 989 */ 990 set_ftime(arcn->org_name, arcn->sb.st_mtime, arcn->sb.st_atime, 1); 991 return; 992} 993 994/* 995 * set_crc() 996 * read a file to calculate its crc. This is a real drag. Archive formats 997 * that have this, end up reading the file twice (we have to write the 998 * header WITH the crc before writing the file contents. Oh well... 999 * Return: 1000 * 0 if was able to calculate the crc, -1 otherwise 1001 */ 1002 1003#if __STDC__ 1004int 1005set_crc(register ARCHD *arcn, register int fd) 1006#else 1007int 1008set_crc(arcn, fd) 1009 register ARCHD *arcn; 1010 register int fd; 1011#endif 1012{ 1013 register int i; 1014 register int res; 1015 off_t cpcnt = 0L; 1016 u_long size; 1017 unsigned long crc = 0L; 1018 char tbuf[FILEBLK]; 1019 struct stat sb; 1020 1021 if (fd < 0) { 1022 /* 1023 * hmm, no fd, should never happen. well no crc then. 1024 */ 1025 arcn->crc = 0L; 1026 return(0); 1027 } 1028 1029 if ((size = (u_long)arcn->sb.st_blksize) > (u_long)sizeof(tbuf)) 1030 size = (u_long)sizeof(tbuf); 1031 1032 /* 1033 * read all the bytes we think that there are in the file. If the user 1034 * is trying to archive an active file, forget this file. 1035 */ 1036 for(;;) { 1037 if ((res = read(fd, tbuf, size)) <= 0) 1038 break; 1039 cpcnt += res; 1040 for (i = 0; i < res; ++i) 1041 crc += (tbuf[i] & 0xff); 1042 } 1043 1044 /* 1045 * safety check. we want to avoid archiving files that are active as 1046 * they can create inconsistant archive copies. 1047 */ 1048 if (cpcnt != arcn->sb.st_size) 1049 warn(1, "File changed size %s", arcn->org_name); 1050 else if (fstat(fd, &sb) < 0) 1051 syswarn(1, errno, "Failed stat on %s", arcn->org_name); 1052 else if (arcn->sb.st_mtime != sb.st_mtime) 1053 warn(1, "File %s was modified during read", arcn->org_name); 1054 else if (lseek(fd, (off_t)0L, SEEK_SET) < 0) 1055 syswarn(1, errno, "File rewind failed on: %s", arcn->org_name); 1056 else { 1057 arcn->crc = crc; 1058 return(0); 1059 } 1060 return(-1); 1061} 1062