file_subs.c revision 1.24
1/* $NetBSD: file_subs.c,v 1.24 2002/10/12 15:39:29 christos 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#include <sys/cdefs.h> 41#if defined(__RCSID) && !defined(lint) 42#if 0 43static char sccsid[] = "@(#)file_subs.c 8.1 (Berkeley) 5/31/93"; 44#else 45__RCSID("$NetBSD: file_subs.c,v 1.24 2002/10/12 15:39:29 christos Exp $"); 46#endif 47#endif /* not lint */ 48 49#include <sys/types.h> 50#include <sys/time.h> 51#include <sys/stat.h> 52#include <unistd.h> 53#include <sys/param.h> 54#include <fcntl.h> 55#include <string.h> 56#include <stdio.h> 57#include <ctype.h> 58#include <errno.h> 59#include <sys/uio.h> 60#include <stdlib.h> 61#include "pax.h" 62#include "extern.h" 63#include "options.h" 64 65static int 66mk_link(char *,struct stat *,char *, int); 67 68/* 69 * routines that deal with file operations such as: creating, removing; 70 * and setting access modes, uid/gid and times of files 71 */ 72 73#define FILEBITS (S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO) 74#define SETBITS (S_ISUID | S_ISGID) 75#define ABITS (FILEBITS | SETBITS) 76 77/* 78 * file_creat() 79 * Create and open a file. 80 * Return: 81 * file descriptor or -1 for failure 82 */ 83 84int 85file_creat(ARCHD *arcn) 86{ 87 int fd = -1; 88 mode_t file_mode; 89 int oerrno; 90 91 /* 92 * assume file doesn't exist, so just try to create it, most times this 93 * works. We have to take special handling when the file does exist. To 94 * detect this, we use O_EXCL. For example when trying to create a 95 * file and a character device or fifo exists with the same name, we 96 * can accidently open the device by mistake (or block waiting to open) 97 * If we find that the open has failed, then figure spend the effort to 98 * figure out why. This strategy was found to have better average 99 * performance in common use than checking the file (and the path) 100 * first with lstat. 101 */ 102 file_mode = arcn->sb.st_mode & FILEBITS; 103 if ((fd = open(arcn->name, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 104 file_mode)) >= 0) 105 return(fd); 106 107 /* 108 * the file seems to exist. First we try to get rid of it (found to be 109 * the second most common failure when traced). If this fails, only 110 * then we go to the expense to check and create the path to the file 111 */ 112 if (unlnk_exist(arcn->name, arcn->type) != 0) 113 return(-1); 114 115 for (;;) { 116 /* 117 * try to open it again, if this fails, check all the nodes in 118 * the path and give it a final try. if chk_path() finds that 119 * it cannot fix anything, we will skip the last attempt 120 */ 121 if ((fd = open(arcn->name, O_WRONLY | O_CREAT | O_TRUNC, 122 file_mode)) >= 0) 123 break; 124 oerrno = errno; 125 if (nodirs || chk_path(arcn->name,arcn->sb.st_uid,arcn->sb.st_gid) < 0) { 126 syswarn(1, oerrno, "Unable to create %s", arcn->name); 127 return(-1); 128 } 129 } 130 return(fd); 131} 132 133/* 134 * file_close() 135 * Close file descriptor to a file just created by pax. Sets modes, 136 * ownership and times as required. 137 * Return: 138 * 0 for success, -1 for failure 139 */ 140 141void 142file_close(ARCHD *arcn, int fd) 143{ 144 int res = 0; 145 146 if (fd < 0) 147 return; 148 if (close(fd) < 0) 149 syswarn(0, errno, "Unable to close file descriptor on %s", 150 arcn->name); 151 152 /* 153 * set owner/groups first as this may strip off mode bits we want 154 * then set file permission modes. Then set file access and 155 * modification times. 156 */ 157 if (pids) 158 res = set_ids(arcn->name, arcn->sb.st_uid, arcn->sb.st_gid); 159 160 /* 161 * IMPORTANT SECURITY NOTE: 162 * if not preserving mode or we cannot set uid/gid, then PROHIBIT 163 * set uid/gid bits 164 */ 165 if (!pmode || res) 166 arcn->sb.st_mode &= ~(SETBITS); 167 if (pmode) 168 set_pmode(arcn->name, arcn->sb.st_mode); 169 if (patime || pmtime) 170 set_ftime(arcn->name, arcn->sb.st_mtime, arcn->sb.st_atime, 0); 171#if HAVE_STRUCT_STAT_ST_FLAGS 172 if (pfflags && arcn->type != PAX_SLK) 173 set_chflags(arcn->name, arcn->sb.st_flags); 174#endif 175} 176 177/* 178 * lnk_creat() 179 * Create a hard link to arcn->ln_name from arcn->name. arcn->ln_name 180 * must exist; 181 * Return: 182 * 0 if ok, -1 otherwise 183 */ 184 185int 186lnk_creat(ARCHD *arcn) 187{ 188 struct stat sb; 189 190 /* 191 * we may be running as root, so we have to be sure that link target 192 * is not a directory, so we lstat and check 193 */ 194 if (lstat(arcn->ln_name, &sb) < 0) { 195 syswarn(1,errno,"Unable to link to %s from %s", arcn->ln_name, 196 arcn->name); 197 return(-1); 198 } 199 200 if (S_ISDIR(sb.st_mode)) { 201 tty_warn(1, "A hard link to the directory %s is not allowed", 202 arcn->ln_name); 203 return(-1); 204 } 205 206 return(mk_link(arcn->ln_name, &sb, arcn->name, 0)); 207} 208 209/* 210 * cross_lnk() 211 * Create a hard link to arcn->org_name from arcn->name. Only used in copy 212 * with the -l flag. No warning or error if this does not succeed (we will 213 * then just create the file) 214 * Return: 215 * 1 if copy() should try to create this file node 216 * 0 if cross_lnk() ok, -1 for fatal flaw (like linking to self). 217 */ 218 219int 220cross_lnk(ARCHD *arcn) 221{ 222 /* 223 * try to make a link to original file (-l flag in copy mode). make 224 * sure we do not try to link to directories in case we are running as 225 * root (and it might succeed). 226 */ 227 if (arcn->type == PAX_DIR) 228 return(1); 229 return(mk_link(arcn->org_name, &(arcn->sb), arcn->name, 1)); 230} 231 232/* 233 * chk_same() 234 * In copy mode if we are not trying to make hard links between the src 235 * and destinations, make sure we are not going to overwrite ourselves by 236 * accident. This slows things down a little, but we have to protect all 237 * those people who make typing errors. 238 * Return: 239 * 1 the target does not exist, go ahead and copy 240 * 0 skip it file exists (-k) or may be the same as source file 241 */ 242 243int 244chk_same(ARCHD *arcn) 245{ 246 struct stat sb; 247 248 /* 249 * if file does not exist, return. if file exists and -k, skip it 250 * quietly 251 */ 252 if (lstat(arcn->name, &sb) < 0) 253 return(1); 254 if (kflag) 255 return(0); 256 257 /* 258 * better make sure the user does not have src == dest by mistake 259 */ 260 if ((arcn->sb.st_dev == sb.st_dev) && (arcn->sb.st_ino == sb.st_ino)) { 261 tty_warn(1, "Unable to copy %s, file would overwrite itself", 262 arcn->name); 263 return(0); 264 } 265 return(1); 266} 267 268/* 269 * mk_link() 270 * try to make a hard link between two files. if ign set, we do not 271 * complain. 272 * Return: 273 * 0 if successful (or we are done with this file but no error, such as 274 * finding the from file exists and the user has set -k). 275 * 1 when ign was set to indicates we could not make the link but we 276 * should try to copy/extract the file as that might work (and is an 277 * allowed option). -1 an error occurred. 278 */ 279 280static int 281mk_link(char *to, struct stat *to_sb, char *from, int ign) 282{ 283 struct stat sb; 284 int oerrno; 285 286 /* 287 * if from file exists, it has to be unlinked to make the link. If the 288 * file exists and -k is set, skip it quietly 289 */ 290 if (lstat(from, &sb) == 0) { 291 if (kflag) 292 return(0); 293 294 /* 295 * make sure it is not the same file, protect the user 296 */ 297 if ((to_sb->st_dev==sb.st_dev)&&(to_sb->st_ino == sb.st_ino)) { 298 tty_warn(1, "Unable to link file %s to itself", to); 299 return(-1);; 300 } 301 302 /* 303 * try to get rid of the file, based on the type 304 */ 305 if (S_ISDIR(sb.st_mode)) { 306 if (rmdir(from) < 0) { 307 syswarn(1, errno, "Unable to remove %s", from); 308 return(-1); 309 } 310 } else if (unlink(from) < 0) { 311 if (!ign) { 312 syswarn(1, errno, "Unable to remove %s", from); 313 return(-1); 314 } 315 return(1); 316 } 317 } 318 319 /* 320 * from file is gone (or did not exist), try to make the hard link. 321 * if it fails, check the path and try it again (if chk_path() says to 322 * try again) 323 */ 324 for (;;) { 325 if (link(to, from) == 0) 326 break; 327 oerrno = errno; 328 if (chk_path(from, to_sb->st_uid, to_sb->st_gid) == 0) 329 continue; 330 if (!ign) { 331 syswarn(1, oerrno, "Could not link to %s from %s", to, 332 from); 333 return(-1); 334 } 335 return(1); 336 } 337 338 /* 339 * all right the link was made 340 */ 341 return(0); 342} 343 344/* 345 * node_creat() 346 * create an entry in the file system (other than a file or hard link). 347 * If successful, sets uid/gid modes and times as required. 348 * Return: 349 * 0 if ok, -1 otherwise 350 */ 351 352int 353node_creat(ARCHD *arcn) 354{ 355 int res; 356 int ign = 0; 357 int oerrno; 358 int pass = 0; 359 mode_t file_mode; 360 struct stat sb; 361 char target[MAXPATHLEN]; 362 char *nm = arcn->name; 363 int len; 364 365 /* 366 * create node based on type, if that fails try to unlink the node and 367 * try again. finally check the path and try again. As noted in the 368 * file and link creation routines, this method seems to exhibit the 369 * best performance in general use workloads. 370 */ 371 file_mode = arcn->sb.st_mode & FILEBITS; 372 373 for (;;) { 374 switch(arcn->type) { 375 case PAX_DIR: 376 /* 377 * If -h (or -L) was given in tar-mode, follow the 378 * potential symlink chain before trying to create the 379 * directory. 380 */ 381 if (strcmp(NM_TAR, argv0) == 0 && Lflag) { 382 while (lstat(nm, &sb) == 0 && 383 S_ISLNK(sb.st_mode)) { 384 len = readlink(nm, target, 385 sizeof target - 1); 386 if (len == -1) { 387 syswarn(0, errno, 388 "cannot follow symlink %s in chain for %s", 389 nm, arcn->name); 390 res = -1; 391 goto badlink; 392 } 393 target[len] = '\0'; 394 nm = target; 395 } 396 } 397 res = mkdir(nm, file_mode); 398 399badlink: 400 if (ign) 401 res = 0; 402 break; 403 case PAX_CHR: 404 file_mode |= S_IFCHR; 405 res = mknod(nm, file_mode, arcn->sb.st_rdev); 406 break; 407 case PAX_BLK: 408 file_mode |= S_IFBLK; 409 res = mknod(nm, file_mode, arcn->sb.st_rdev); 410 break; 411 case PAX_FIF: 412 res = mkfifo(nm, file_mode); 413 break; 414 case PAX_SCK: 415 /* 416 * Skip sockets, operation has no meaning under BSD 417 */ 418 tty_warn(0, 419 "%s skipped. Sockets cannot be copied or extracted", 420 nm); 421 return(-1); 422 case PAX_SLK: 423 res = symlink(arcn->ln_name, nm); 424 break; 425 case PAX_CTG: 426 case PAX_HLK: 427 case PAX_HRG: 428 case PAX_REG: 429 default: 430 /* 431 * we should never get here 432 */ 433 tty_warn(0, "%s has an unknown file type, skipping", 434 nm); 435 return(-1); 436 } 437 438 /* 439 * if we were able to create the node break out of the loop, 440 * otherwise try to unlink the node and try again. if that 441 * fails check the full path and try a final time. 442 */ 443 if (res == 0) 444 break; 445 446 /* 447 * we failed to make the node 448 */ 449 oerrno = errno; 450 if ((ign = unlnk_exist(nm, arcn->type)) < 0) 451 return(-1); 452 453 if (++pass <= 1) 454 continue; 455 456 if (nodirs || chk_path(nm,arcn->sb.st_uid,arcn->sb.st_gid) < 0) { 457 syswarn(1, oerrno, "Could not create: %s", nm); 458 return(-1); 459 } 460 } 461 462 /* 463 * we were able to create the node. set uid/gid, modes and times 464 */ 465#if HAVE_LCHOWN 466 if (pids) 467#else 468 if (pids && arcn->type != PAX_SLK) 469#endif 470 res = set_ids(nm, arcn->sb.st_uid, arcn->sb.st_gid); 471 else 472 res = 0; 473 474 /* 475 * IMPORTANT SECURITY NOTE: 476 * if not preserving mode or we cannot set uid/gid, then PROHIBIT any 477 * set uid/gid bits 478 */ 479 if (!pmode || res) 480 arcn->sb.st_mode &= ~(SETBITS); 481#if HAVE_LCHMOD 482 if (pmode) 483#else 484 if (pmode && arcn->type != PAX_SLK) 485#endif 486 set_pmode(arcn->name, arcn->sb.st_mode); 487 488 if (arcn->type == PAX_DIR && strcmp(NM_CPIO, argv0) != 0) { 489 /* 490 * Dirs must be processed again at end of extract to set times 491 * and modes to agree with those stored in the archive. However 492 * to allow extract to continue, we may have to also set owner 493 * rights. This allows nodes in the archive that are children 494 * of this directory to be extracted without failure. Both time 495 * and modes will be fixed after the entire archive is read and 496 * before pax exits. 497 */ 498 if (access(nm, R_OK | W_OK | X_OK) < 0) { 499 if (lstat(nm, &sb) < 0) { 500 syswarn(0, errno,"Could not access %s (stat)", 501 arcn->name); 502 set_pmode(nm,file_mode | S_IRWXU); 503 } else { 504 /* 505 * We have to add rights to the dir, so we make 506 * sure to restore the mode. The mode must be 507 * restored AS CREATED and not as stored if 508 * pmode is not set. 509 */ 510 set_pmode(nm, 511 ((sb.st_mode & FILEBITS) | S_IRWXU)); 512 if (!pmode) 513 arcn->sb.st_mode = sb.st_mode; 514 } 515 516 /* 517 * we have to force the mode to what was set here, 518 * since we changed it from the default as created. 519 */ 520 add_dir(nm, arcn->nlen, &(arcn->sb), 1); 521 } else if (pmode || patime || pmtime) 522 add_dir(nm, arcn->nlen, &(arcn->sb), 0); 523 } 524 525#if HAVE_LUTIMES 526 if (patime || pmtime) 527#else 528 if ((patime || pmtime) && arcn->type != PAX_SLK) 529#endif 530 set_ftime(arcn->name, arcn->sb.st_mtime, arcn->sb.st_atime, 0); 531 532#if HAVE_STRUCT_STAT_ST_FLAGS 533 if (pfflags && arcn->type != PAX_SLK) 534 set_chflags(arcn->name, arcn->sb.st_flags); 535#endif 536 return(0); 537} 538 539/* 540 * unlnk_exist() 541 * Remove node from file system with the specified name. We pass the type 542 * of the node that is going to replace it. When we try to create a 543 * directory and find that it already exists, we allow processing to 544 * continue as proper modes etc will always be set for it later on. 545 * Return: 546 * 0 is ok to proceed, no file with the specified name exists 547 * -1 we were unable to remove the node, or we should not remove it (-k) 548 * 1 we found a directory and we were going to create a directory. 549 */ 550 551int 552unlnk_exist(char *name, int type) 553{ 554 struct stat sb; 555 556 /* 557 * the file does not exist, or -k we are done 558 */ 559 if (lstat(name, &sb) < 0) 560 return(0); 561 if (kflag) 562 return(-1); 563 564 if (S_ISDIR(sb.st_mode)) { 565 /* 566 * try to remove a directory, if it fails and we were going to 567 * create a directory anyway, tell the caller (return a 1) 568 */ 569 if (rmdir(name) < 0) { 570 if (type == PAX_DIR) 571 return(1); 572 syswarn(1,errno,"Unable to remove directory %s", name); 573 return(-1); 574 } 575 return(0); 576 } 577 578 /* 579 * try to get rid of all non-directory type nodes 580 */ 581 if (unlink(name) < 0) { 582 syswarn(1, errno, "Could not unlink %s", name); 583 return(-1); 584 } 585 return(0); 586} 587 588/* 589 * chk_path() 590 * We were trying to create some kind of node in the file system and it 591 * failed. chk_path() makes sure the path up to the node exists and is 592 * writeable. When we have to create a directory that is missing along the 593 * path somewhere, the directory we create will be set to the same 594 * uid/gid as the file has (when uid and gid are being preserved). 595 * NOTE: this routine is a real performance loss. It is only used as a 596 * last resort when trying to create entries in the file system. 597 * Return: 598 * -1 when it could find nothing it is allowed to fix. 599 * 0 otherwise 600 */ 601 602int 603chk_path( char *name, uid_t st_uid, gid_t st_gid) 604{ 605 char *spt = name; 606 struct stat sb; 607 int retval = -1; 608 609 /* 610 * watch out for paths with nodes stored directly in / (e.g. /bozo) 611 */ 612 if (*spt == '/') 613 ++spt; 614 615 for(;;) { 616 /* 617 * work forward from the first / and check each part of 618 * the path 619 */ 620 spt = strchr(spt, '/'); 621 if (spt == NULL) 622 break; 623 *spt = '\0'; 624 625 /* 626 * if it exists we assume it is a directory, it is not within 627 * the spec (at least it seems to read that way) to alter the 628 * file system for nodes NOT EXPLICITLY stored on the archive. 629 * If that assumption is changed, you would test the node here 630 * and figure out how to get rid of it (probably like some 631 * recursive unlink()) or fix up the directory permissions if 632 * required (do an access()). 633 */ 634 if (lstat(name, &sb) == 0) { 635 *(spt++) = '/'; 636 continue; 637 } 638 639 /* 640 * the path fails at this point, see if we can create the 641 * needed directory and continue on 642 */ 643 if (mkdir(name, S_IRWXU | S_IRWXG | S_IRWXO) < 0) { 644 *spt = '/'; 645 retval = -1; 646 break; 647 } 648 649 /* 650 * we were able to create the directory. We will tell the 651 * caller that we found something to fix, and it is ok to try 652 * and create the node again. 653 */ 654 retval = 0; 655 if (pids) 656 (void)set_ids(name, st_uid, st_gid); 657 658 /* 659 * make sure the user doesn't have some strange umask that 660 * causes this newly created directory to be unusable. We fix 661 * the modes and restore them back to the creation default at 662 * the end of pax 663 */ 664 if ((access(name, R_OK | W_OK | X_OK) < 0) && 665 (lstat(name, &sb) == 0)) { 666 set_pmode(name, ((sb.st_mode & FILEBITS) | S_IRWXU)); 667 add_dir(name, spt - name, &sb, 1); 668 } 669 *(spt++) = '/'; 670 continue; 671 } 672 return(retval); 673} 674 675/* 676 * set_ftime() 677 * Set the access time and modification time for a named file. If frc 678 * is non-zero we force these times to be set even if the user did not 679 * request access and/or modification time preservation (this is also 680 * used by -t to reset access times). 681 * When ign is zero, only those times the user has asked for are set, the 682 * other ones are left alone. We do not assume the un-documented feature 683 * of many utimes() implementations that consider a 0 time value as a do 684 * not set request. 685 */ 686 687void 688set_ftime(char *fnm, time_t mtime, time_t atime, int frc) 689{ 690 struct timeval tv[2]; 691 struct stat sb; 692 693 tv[0].tv_sec = (long)atime; 694 tv[0].tv_usec = 0; 695 tv[1].tv_sec = (long)mtime; 696 tv[1].tv_usec = 0; 697 if (!frc && (!patime || !pmtime)) { 698 /* 699 * if we are not forcing, only set those times the user wants 700 * set. We get the current values of the times if we need them. 701 */ 702 if (lstat(fnm, &sb) == 0) { 703#ifdef BSD4_4 704 if (!patime) 705 TIMESPEC_TO_TIMEVAL(&tv[0], &sb.st_atimespec); 706 if (!pmtime) 707 TIMESPEC_TO_TIMEVAL(&tv[1], &sb.st_mtimespec); 708#else 709 if (!patime) 710 tv[0].tv_sec = sb.st_atime; 711 if (!pmtime) 712 tv[1].tv_sec = sb.st_mtime; 713#endif 714 } else 715 syswarn(0,errno,"Unable to obtain file stats %s", fnm); 716 } 717 718 /* 719 * set the times 720 */ 721#if HAVE_LUTIMES 722 if (lutimes(fnm, tv)) 723#else 724 if (utimes(fnm, tv)) 725#endif 726 syswarn(1, errno, "Access/modification time set failed on: %s", 727 fnm); 728 return; 729} 730 731/* 732 * set_ids() 733 * set the uid and gid of a file system node 734 * Return: 735 * 0 when set, -1 on failure 736 */ 737 738int 739set_ids(char *fnm, uid_t uid, gid_t gid) 740{ 741#if HAVE_LCHOWN 742 if (lchown(fnm, uid, gid)) 743#else 744 if (chown(fnm, uid, gid)) 745#endif 746 { 747 syswarn(1, errno, "Unable to set file uid/gid of %s", fnm); 748 return(-1); 749 } 750 return(0); 751} 752 753/* 754 * set_pmode() 755 * Set file access mode 756 */ 757 758void 759set_pmode(char *fnm, mode_t mode) 760{ 761 mode &= ABITS; 762#if HAVE_LCHMOD 763 if (lchmod(fnm, mode)) 764#else 765 if (chmod(fnm, mode)) 766#endif 767 syswarn(1, errno, "Could not set permissions on %s", fnm); 768 return; 769} 770 771/* 772 * set_chflags() 773 * Set 4.4BSD file flags 774 */ 775void 776set_chflags(char *fnm, u_int32_t flags) 777{ 778 779#if 0 780 if (chflags(fnm, flags) < 0 && errno != EOPNOTSUPP) 781 syswarn(1, errno, "Could not set file flags on %s", fnm); 782#endif 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 boundaries. 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 boundaries 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 834int 835file_write(int fd, char *str, int cnt, int *rem, int *isempt, int sz, 836 char *name) 837{ 838 char *pt; 839 char *end; 840 int wcnt; 841 char *st = str; 842 843 /* 844 * while we have data to process 845 */ 846 while (cnt) { 847 if (!*rem) { 848 /* 849 * We are now at the start of file system block again 850 * (or what we think one is...). start looking for 851 * empty blocks again 852 */ 853 *isempt = 1; 854 *rem = sz; 855 } 856 857 /* 858 * only examine up to the end of the current file block or 859 * remaining characters to write, whatever is smaller 860 */ 861 wcnt = MIN(cnt, *rem); 862 cnt -= wcnt; 863 *rem -= wcnt; 864 if (*isempt) { 865 /* 866 * have not written to this block yet, so we keep 867 * looking for zero's 868 */ 869 pt = st; 870 end = st + wcnt; 871 872 /* 873 * look for a zero filled buffer 874 */ 875 while ((pt < end) && (*pt == '\0')) 876 ++pt; 877 878 if (pt == end) { 879 /* 880 * skip, buf is empty so far 881 */ 882 if (fd > -1 && 883 lseek(fd, (off_t)wcnt, SEEK_CUR) < 0) { 884 syswarn(1,errno,"File seek on %s", 885 name); 886 return(-1); 887 } 888 st = pt; 889 continue; 890 } 891 /* 892 * drat, the buf is not zero filled 893 */ 894 *isempt = 0; 895 } 896 897 /* 898 * have non-zero data in this file system block, have to write 899 */ 900 if (fd == -1) { 901 /* GNU hack */ 902 if (gnu_hack_string) 903 err(1, "WARNING! Major Internal Error! GNU hack Failing!"); 904 gnu_hack_string = malloc(wcnt + 1); 905 if (gnu_hack_string == NULL) { 906 tty_warn(1, "Out of memory"); 907 return(-1); 908 } 909 strncpy(gnu_hack_string, st, wcnt); 910 gnu_hack_string[wcnt] = 0; 911 } else if (xwrite(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 927void 928file_flush(int fd, char *fname, int isempt) 929{ 930 static char blnk[] = "\0"; 931 932 /* 933 * silly test, but make sure we are only called when the last block is 934 * filled with all zeros. 935 */ 936 if (!isempt) 937 return; 938 939 /* 940 * move back one byte and write a zero 941 */ 942 if (lseek(fd, (off_t)-1, SEEK_CUR) < 0) { 943 syswarn(1, errno, "Failed seek on file %s", fname); 944 return; 945 } 946 947 if (write_with_restart(fd, blnk, 1) < 0) 948 syswarn(1, errno, "Failed write to file %s", fname); 949 return; 950} 951 952/* 953 * rdfile_close() 954 * close a file we have been reading (to copy or archive). If we have to 955 * reset access time (tflag) do so (the times are stored in arcn). 956 */ 957 958void 959rdfile_close(ARCHD *arcn, int *fd) 960{ 961 /* 962 * make sure the file is open 963 */ 964 if (*fd < 0) 965 return; 966 967 (void)close(*fd); 968 *fd = -1; 969 if (!tflag) 970 return; 971 972 /* 973 * user wants last access time reset 974 */ 975 set_ftime(arcn->org_name, arcn->sb.st_mtime, arcn->sb.st_atime, 1); 976 return; 977} 978 979/* 980 * set_crc() 981 * read a file to calculate its crc. This is a real drag. Archive formats 982 * that have this, end up reading the file twice (we have to write the 983 * header WITH the crc before writing the file contents. Oh well... 984 * Return: 985 * 0 if was able to calculate the crc, -1 otherwise 986 */ 987 988int 989set_crc(ARCHD *arcn, int fd) 990{ 991 int i; 992 int res; 993 off_t cpcnt = 0L; 994 u_long size; 995 unsigned long crc = 0L; 996 char tbuf[FILEBLK]; 997 struct stat sb; 998 999 if (fd < 0) { 1000 /* 1001 * hmm, no fd, should never happen. well no crc then. 1002 */ 1003 arcn->crc = 0L; 1004 return(0); 1005 } 1006 1007 if ((size = (u_long)arcn->sb.st_blksize) > (u_long)sizeof(tbuf)) 1008 size = (u_long)sizeof(tbuf); 1009 1010 /* 1011 * read all the bytes we think that there are in the file. If the user 1012 * is trying to archive an active file, forget this file. 1013 */ 1014 for(;;) { 1015 if ((res = read(fd, tbuf, size)) <= 0) 1016 break; 1017 cpcnt += res; 1018 for (i = 0; i < res; ++i) 1019 crc += (tbuf[i] & 0xff); 1020 } 1021 1022 /* 1023 * safety check. we want to avoid archiving files that are active as 1024 * they can create inconsistant archive copies. 1025 */ 1026 if (cpcnt != arcn->sb.st_size) 1027 tty_warn(1, "File changed size %s", arcn->org_name); 1028 else if (fstat(fd, &sb) < 0) 1029 syswarn(1, errno, "Failed stat on %s", arcn->org_name); 1030 else if (arcn->sb.st_mtime != sb.st_mtime) 1031 tty_warn(1, "File %s was modified during read", arcn->org_name); 1032 else if (lseek(fd, (off_t)0L, SEEK_SET) < 0) 1033 syswarn(1, errno, "File rewind failed on: %s", arcn->org_name); 1034 else { 1035 arcn->crc = crc; 1036 return(0); 1037 } 1038 return(-1); 1039} 1040