buf_subs.c revision 1.10
1/* $NetBSD: buf_subs.c,v 1.10 1999/10/22 10:38:40 mrg 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#ifndef lint 42#if 0 43static char sccsid[] = "@(#)buf_subs.c 8.2 (Berkeley) 4/18/94"; 44#else 45__RCSID("$NetBSD: buf_subs.c,v 1.10 1999/10/22 10:38:40 mrg 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 <sys/param.h> 53#include <stdio.h> 54#include <ctype.h> 55#include <errno.h> 56#include <unistd.h> 57#include <stdlib.h> 58#include <string.h> 59#include "pax.h" 60#include "extern.h" 61 62/* 63 * routines which implement archive and file buffering 64 */ 65 66#define MINFBSZ 512 /* default block size for hole detect */ 67#define MAXFLT 10 /* default media read error limit */ 68 69/* 70 * Need to change bufmem to dynamic allocation when the upper 71 * limit on blocking size is removed (though that will violate pax spec) 72 * MAXBLK define and tests will also need to be updated. 73 */ 74static char bufmem[MAXBLK+BLKMULT]; /* i/o buffer + pushback id space */ 75static char *buf; /* normal start of i/o buffer */ 76static char *bufend; /* end or last char in i/o buffer */ 77static char *bufpt; /* read/write point in i/o buffer */ 78int blksz = MAXBLK; /* block input/output size in bytes */ 79int wrblksz; /* user spec output size in bytes */ 80int maxflt = MAXFLT; /* MAX consecutive media errors */ 81int rdblksz; /* first read blksize (tapes only) */ 82off_t wrlimit; /* # of bytes written per archive vol */ 83off_t wrcnt; /* # of bytes written on current vol */ 84off_t rdcnt; /* # of bytes read on current vol */ 85 86/* 87 * wr_start() 88 * set up the buffering system to operate in a write mode 89 * Return: 90 * 0 if ok, -1 if the user specified write block size violates pax spec 91 */ 92 93#if __STDC__ 94int 95wr_start(void) 96#else 97int 98wr_start() 99#endif 100{ 101 buf = &(bufmem[BLKMULT]); 102 /* 103 * Check to make sure the write block size meets pax specs. If the user 104 * does not specify a blocksize, we use the format default blocksize. 105 * We must be picky on writes, so we do not allow the user to create an 106 * archive that might be hard to read elsewhere. If all ok, we then 107 * open the first archive volume 108 */ 109 if (!wrblksz) 110 wrblksz = frmt->bsz; 111 if (wrblksz > MAXBLK) { 112 tty_warn(1, "Write block size of %d too large, maximium is: %d", 113 wrblksz, MAXBLK); 114 return(-1); 115 } 116 if (wrblksz % BLKMULT) { 117 tty_warn(1, "Write block size of %d is not a %d byte multiple", 118 wrblksz, BLKMULT); 119 return(-1); 120 } 121 122 /* 123 * we only allow wrblksz to be used with all archive operations 124 */ 125 blksz = rdblksz = wrblksz; 126 if ((ar_open(arcname) < 0) && (ar_next() < 0)) 127 return(-1); 128 wrcnt = 0; 129 bufend = buf + wrblksz; 130 bufpt = buf; 131 return(0); 132} 133 134/* 135 * rd_start() 136 * set up buffering system to read an archive 137 * Return: 138 * 0 if ok, -1 otherwise 139 */ 140 141#if __STDC__ 142int 143rd_start(void) 144#else 145int 146rd_start() 147#endif 148{ 149 /* 150 * leave space for the header pushback (see get_arc()). If we are 151 * going to append and user specified a write block size, check it 152 * right away 153 */ 154 buf = &(bufmem[BLKMULT]); 155 if ((act == APPND) && wrblksz) { 156 if (wrblksz > MAXBLK) { 157 tty_warn(1, 158 "Write block size %d too large, maximium is: %d", 159 wrblksz, MAXBLK); 160 return(-1); 161 } 162 if (wrblksz % BLKMULT) { 163 tty_warn(1, 164 "Write block size %d is not a %d byte multiple", 165 wrblksz, BLKMULT); 166 return(-1); 167 } 168 } 169 170 /* 171 * open the archive 172 */ 173 if ((ar_open(arcname) < 0) && (ar_next() < 0)) 174 return(-1); 175 bufend = buf + rdblksz; 176 bufpt = bufend; 177 rdcnt = 0; 178 return(0); 179} 180 181/* 182 * cp_start() 183 * set up buffer system for copying within the file system 184 */ 185 186#if __STDC__ 187void 188cp_start(void) 189#else 190void 191cp_start() 192#endif 193{ 194 buf = &(bufmem[BLKMULT]); 195 rdblksz = blksz = MAXBLK; 196} 197 198/* 199 * appnd_start() 200 * Set up the buffering system to append new members to an archive that 201 * was just read. The last block(s) of an archive may contain a format 202 * specific trailer. To append a new member, this trailer has to be 203 * removed from the archive. The first byte of the trailer is replaced by 204 * the start of the header of the first file added to the archive. The 205 * format specific end read function tells us how many bytes to move 206 * backwards in the archive to be positioned BEFORE the trailer. Two 207 * different postions have to be adjusted, the O.S. file offset (e.g. the 208 * position of the tape head) and the write point within the data we have 209 * stored in the read (soon to become write) buffer. We may have to move 210 * back several records (the number depends on the size of the archive 211 * record and the size of the format trailer) to read up the record where 212 * the first byte of the trailer is recorded. Trailers may span (and 213 * overlap) record boundries. 214 * We first calculate which record has the first byte of the trailer. We 215 * move the OS file offset back to the start of this record and read it 216 * up. We set the buffer write pointer to be at this byte (the byte where 217 * the trailer starts). We then move the OS file pointer back to the 218 * start of this record so a flush of this buffer will replace the record 219 * in the archive. 220 * A major problem is rewriting this last record. For archives stored 221 * on disk files, this is trival. However, many devices are really picky 222 * about the conditions under which they will allow a write to occur. 223 * Often devices restrict the conditions where writes can be made writes, 224 * so it may not be feasable to append archives stored on all types of 225 * devices. 226 * Return: 227 * 0 for success, -1 for failure 228 */ 229 230#if __STDC__ 231int 232appnd_start(off_t skcnt) 233#else 234int 235appnd_start(skcnt) 236 off_t skcnt; 237#endif 238{ 239 int res; 240 off_t cnt; 241 242 if (exit_val != 0) { 243 tty_warn(0, "Cannot append to an archive that may have flaws."); 244 return(-1); 245 } 246 /* 247 * if the user did not specify a write blocksize, inherit the size used 248 * in the last archive volume read. (If a is set we still use rdblksz 249 * until next volume, cannot shift sizes within a single volume). 250 */ 251 if (!wrblksz) 252 wrblksz = blksz = rdblksz; 253 else 254 blksz = rdblksz; 255 256 /* 257 * make sure that this volume allows appends 258 */ 259 if (ar_app_ok() < 0) 260 return(-1); 261 262 /* 263 * Calculate bytes to move back and move in front of record where we 264 * need to start writing from. Remember we have to add in any padding 265 * that might be in the buffer after the trailer in the last block. We 266 * travel skcnt + padding ROUNDED UP to blksize. 267 */ 268 skcnt += bufend - bufpt; 269 if ((cnt = (skcnt/blksz) * blksz) < skcnt) 270 cnt += blksz; 271 if (ar_rev((off_t)cnt) < 0) 272 goto out; 273 274 /* 275 * We may have gone too far if there is valid data in the block we are 276 * now in front of, read up the block and position the pointer after 277 * the valid data. 278 */ 279 if ((cnt -= skcnt) > 0) { 280 /* 281 * watch out for stupid tape drives. ar_rev() will set rdblksz 282 * to be real physical blocksize so we must loop until we get 283 * the old rdblksz (now in blksz). If ar_rev() fouls up the 284 * determination of the physical block size, we will fail. 285 */ 286 bufpt = buf; 287 bufend = buf + blksz; 288 while (bufpt < bufend) { 289 if ((res = ar_read(bufpt, rdblksz)) <= 0) 290 goto out; 291 bufpt += res; 292 } 293 if (ar_rev((off_t)(bufpt - buf)) < 0) 294 goto out; 295 bufpt = buf + cnt; 296 bufend = buf + blksz; 297 } else { 298 /* 299 * buffer is empty 300 */ 301 bufend = buf + blksz; 302 bufpt = buf; 303 } 304 rdblksz = blksz; 305 rdcnt -= skcnt; 306 wrcnt = 0; 307 308 /* 309 * At this point we are ready to write. If the device requires special 310 * handling to write at a point were previously recorded data resides, 311 * that is handled in ar_set_wr(). From now on we operate under normal 312 * ARCHIVE mode (write) conditions 313 */ 314 if (ar_set_wr() < 0) 315 return(-1); 316 act = ARCHIVE; 317 return(0); 318 319 out: 320 tty_warn(1, "Unable to rewrite archive trailer, cannot append."); 321 return(-1); 322} 323 324/* 325 * rd_sync() 326 * A read error occurred on this archive volume. Resync the buffer and 327 * try to reset the device (if possible) so we can continue to read. Keep 328 * trying to do this until we get a valid read, or we reach the limit on 329 * consecutive read faults (at which point we give up). The user can 330 * adjust the read error limit through a command line option. 331 * Returns: 332 * 0 on success, and -1 on failure 333 */ 334 335#if __STDC__ 336int 337rd_sync(void) 338#else 339int 340rd_sync() 341#endif 342{ 343 int errcnt = 0; 344 int res; 345 346 /* 347 * if the user says bail out on first fault, we are out of here... 348 */ 349 if (maxflt == 0) 350 return(-1); 351 if (act == APPND) { 352 tty_warn(1, 353 "Unable to append when there are archive read errors."); 354 return(-1); 355 } 356 357 /* 358 * poke at device and try to get past media error 359 */ 360 if (ar_rdsync() < 0) { 361 if (ar_next() < 0) 362 return(-1); 363 else 364 rdcnt = 0; 365 } 366 367 for (;;) { 368 if ((res = ar_read(buf, blksz)) > 0) { 369 /* 370 * All right! got some data, fill that buffer 371 */ 372 bufpt = buf; 373 bufend = buf + res; 374 rdcnt += res; 375 return(0); 376 } 377 378 /* 379 * Oh well, yet another failed read... 380 * if error limit reached, ditch. o.w. poke device to move past 381 * bad media and try again. if media is badly damaged, we ask 382 * the poor (and upset user at this point) for the next archive 383 * volume. remember the goal on reads is to get the most we 384 * can extract out of the archive. 385 */ 386 if ((maxflt > 0) && (++errcnt > maxflt)) 387 tty_warn(0, 388 "Archive read error limit (%d) reached",maxflt); 389 else if (ar_rdsync() == 0) 390 continue; 391 if (ar_next() < 0) 392 break; 393 rdcnt = 0; 394 errcnt = 0; 395 } 396 return(-1); 397} 398 399/* 400 * pback() 401 * push the data used during the archive id phase back into the I/O 402 * buffer. This is required as we cannot be sure that the header does NOT 403 * overlap a block boundry (as in the case we are trying to recover a 404 * flawed archived). This was not designed to be used for any other 405 * purpose. (What software engineering, HA!) 406 * WARNING: do not even THINK of pback greater than BLKMULT, unless the 407 * pback space is increased. 408 */ 409 410#if __STDC__ 411void 412pback(char *pt, int cnt) 413#else 414void 415pback(pt, cnt) 416 char *pt; 417 int cnt; 418#endif 419{ 420 bufpt -= cnt; 421 memcpy(bufpt, pt, cnt); 422 return; 423} 424 425/* 426 * rd_skip() 427 * skip foward in the archive during a archive read. Used to get quickly 428 * past file data and padding for files the user did NOT select. 429 * Return: 430 * 0 if ok, -1 failure, and 1 when EOF on the archive volume was detected. 431 */ 432 433#if __STDC__ 434int 435rd_skip(off_t skcnt) 436#else 437int 438rd_skip(skcnt) 439 off_t skcnt; 440#endif 441{ 442 off_t res; 443 off_t cnt; 444 off_t skipped = 0; 445 446 /* 447 * consume what data we have in the buffer. If we have to move foward 448 * whole records, we call the low level skip function to see if we can 449 * move within the archive without doing the expensive reads on data we 450 * do not want. 451 */ 452 if (skcnt == 0) 453 return(0); 454 res = MIN((bufend - bufpt), skcnt); 455 bufpt += res; 456 skcnt -= res; 457 458 /* 459 * if skcnt is now 0, then no additional i/o is needed 460 */ 461 if (skcnt == 0) 462 return(0); 463 464 /* 465 * We have to read more, calculate complete and partial record reads 466 * based on rdblksz. we skip over "cnt" complete records 467 */ 468 res = skcnt%rdblksz; 469 cnt = (skcnt/rdblksz) * rdblksz; 470 471 /* 472 * if the skip fails, we will have to resync. ar_fow will tell us 473 * how much it can skip over. We will have to read the rest. 474 */ 475 if (ar_fow(cnt, &skipped) < 0) 476 return(-1); 477 res += cnt - skipped; 478 rdcnt += skipped; 479 480 /* 481 * what is left we have to read (which may be the whole thing if 482 * ar_fow() told us the device can only read to skip records); 483 */ 484 while (res > 0L) { 485 cnt = bufend - bufpt; 486 /* 487 * if the read fails, we will have to resync 488 */ 489 if ((cnt <= 0) && ((cnt = buf_fill()) < 0)) 490 return(-1); 491 if (cnt == 0) 492 return(1); 493 cnt = MIN(cnt, res); 494 bufpt += cnt; 495 res -= cnt; 496 } 497 return(0); 498} 499 500/* 501 * wr_fin() 502 * flush out any data (and pad if required) the last block. We always pad 503 * with zero (even though we do not have to). Padding with 0 makes it a 504 * lot easier to recover if the archive is damaged. zero paddding SHOULD 505 * BE a requirement.... 506 */ 507 508#if __STDC__ 509void 510wr_fin(void) 511#else 512void 513wr_fin() 514#endif 515{ 516 if (bufpt > buf) { 517 memset(bufpt, 0, bufend - bufpt); 518 bufpt = bufend; 519 (void)buf_flush(blksz); 520 } 521} 522 523/* 524 * wr_rdbuf() 525 * fill the write buffer from data passed to it in a buffer (usually used 526 * by format specific write routines to pass a file header). On failure we 527 * punt. We do not allow the user to continue to write flawed archives. 528 * We assume these headers are not very large (the memory copy we use is 529 * a bit expensive). 530 * Return: 531 * 0 if buffer was filled ok, -1 o.w. (buffer flush failure) 532 */ 533 534#if __STDC__ 535int 536wr_rdbuf(char *out, int outcnt) 537#else 538int 539wr_rdbuf(out, outcnt) 540 char *out; 541 int outcnt; 542#endif 543{ 544 int cnt; 545 546 /* 547 * while there is data to copy copy into the write buffer. when the 548 * write buffer fills, flush it to the archive and continue 549 */ 550 while (outcnt > 0) { 551 cnt = bufend - bufpt; 552 if ((cnt <= 0) && ((cnt = buf_flush(blksz)) < 0)) 553 return(-1); 554 /* 555 * only move what we have space for 556 */ 557 cnt = MIN(cnt, outcnt); 558 memcpy(bufpt, out, cnt); 559 bufpt += cnt; 560 out += cnt; 561 outcnt -= cnt; 562 } 563 return(0); 564} 565 566/* 567 * rd_wrbuf() 568 * copy from the read buffer into a supplied buffer a specified number of 569 * bytes. If the read buffer is empty fill it and continue to copy. 570 * usually used to obtain a file header for processing by a format 571 * specific read routine. 572 * Return 573 * number of bytes copied to the buffer, 0 indicates EOF on archive volume, 574 * -1 is a read error 575 */ 576 577#if __STDC__ 578int 579rd_wrbuf(char *in, int cpcnt) 580#else 581int 582rd_wrbuf(in, cpcnt) 583 char *in; 584 int cpcnt; 585#endif 586{ 587 int res; 588 int cnt; 589 int incnt = cpcnt; 590 591 /* 592 * loop until we fill the buffer with the requested number of bytes 593 */ 594 while (incnt > 0) { 595 cnt = bufend - bufpt; 596 if ((cnt <= 0) && ((cnt = buf_fill()) <= 0)) { 597 /* 598 * read error, return what we got (or the error if 599 * no data was copied). The caller must know that an 600 * error occured and has the best knowledge what to 601 * do with it 602 */ 603 if ((res = cpcnt - incnt) > 0) 604 return(res); 605 return(cnt); 606 } 607 608 /* 609 * calculate how much data to copy based on whats left and 610 * state of buffer 611 */ 612 cnt = MIN(cnt, incnt); 613 memcpy(in, bufpt, cnt); 614 bufpt += cnt; 615 incnt -= cnt; 616 in += cnt; 617 } 618 return(cpcnt); 619} 620 621/* 622 * wr_skip() 623 * skip foward during a write. In other words add padding to the file. 624 * we add zero filled padding as it makes flawed archives much easier to 625 * recover from. the caller tells us how many bytes of padding to add 626 * This routine was not designed to add HUGE amount of padding, just small 627 * amounts (a few 512 byte blocks at most) 628 * Return: 629 * 0 if ok, -1 if there was a buf_flush failure 630 */ 631 632#if __STDC__ 633int 634wr_skip(off_t skcnt) 635#else 636int 637wr_skip(skcnt) 638 off_t skcnt; 639#endif 640{ 641 int cnt; 642 643 /* 644 * loop while there is more padding to add 645 */ 646 while (skcnt > 0L) { 647 cnt = bufend - bufpt; 648 if ((cnt <= 0) && ((cnt = buf_flush(blksz)) < 0)) 649 return(-1); 650 cnt = MIN(cnt, skcnt); 651 memset(bufpt, 0, cnt); 652 bufpt += cnt; 653 skcnt -= cnt; 654 } 655 return(0); 656} 657 658/* 659 * wr_rdfile() 660 * fill write buffer with the contents of a file. We are passed an open 661 * file descriptor to the file an the archive structure that describes the 662 * file we are storing. The variable "left" is modified to contain the 663 * number of bytes of the file we were NOT able to write to the archive. 664 * it is important that we always write EXACTLY the number of bytes that 665 * the format specific write routine told us to. The file can also get 666 * bigger, so reading to the end of file would create an improper archive, 667 * we just detect this case and warn the user. We never create a bad 668 * archive if we can avoid it. Of course trying to archive files that are 669 * active is asking for trouble. It we fail, we pass back how much we 670 * could NOT copy and let the caller deal with it. 671 * Return: 672 * 0 ok, -1 if archive write failure. a short read of the file returns a 673 * 0, but "left" is set to be greater than zero. 674 */ 675 676#if __STDC__ 677int 678wr_rdfile(ARCHD *arcn, int ifd, off_t *left) 679#else 680int 681wr_rdfile(arcn, ifd, left) 682 ARCHD *arcn; 683 int ifd; 684 off_t *left; 685#endif 686{ 687 int cnt; 688 int res = 0; 689 off_t size = arcn->sb.st_size; 690 struct stat sb; 691 692 /* 693 * while there are more bytes to write 694 */ 695 while (size > 0L) { 696 cnt = bufend - bufpt; 697 if ((cnt <= 0) && ((cnt = buf_flush(blksz)) < 0)) { 698 *left = size; 699 return(-1); 700 } 701 cnt = MIN(cnt, size); 702 if ((res = read(ifd, bufpt, cnt)) <= 0) 703 break; 704 size -= res; 705 bufpt += res; 706 } 707 708 /* 709 * better check the file did not change during this operation 710 * or the file read failed. 711 */ 712 if (res < 0) 713 syswarn(1, errno, "Read fault on %s", arcn->org_name); 714 else if (size != 0L) 715 tty_warn(1, "File changed size during read %s", arcn->org_name); 716 else if (fstat(ifd, &sb) < 0) 717 syswarn(1, errno, "Failed stat on %s", arcn->org_name); 718 else if (arcn->sb.st_mtime != sb.st_mtime) 719 tty_warn(1, "File %s was modified during copy to archive", 720 arcn->org_name); 721 *left = size; 722 return(0); 723} 724 725/* 726 * rd_wrfile() 727 * extract the contents of a file from the archive. If we are unable to 728 * extract the entire file (due to failure to write the file) we return 729 * the numbers of bytes we did NOT process. This way the caller knows how 730 * many bytes to skip past to find the next archive header. If the failure 731 * was due to an archive read, we will catch that when we try to skip. If 732 * the format supplies a file data crc value, we calculate the actual crc 733 * so that it can be compared to the value stored in the header 734 * NOTE: 735 * We call a special function to write the file. This function attempts to 736 * restore file holes (blocks of zeros) into the file. When files are 737 * sparse this saves space, and is a LOT faster. For non sparse files 738 * the performance hit is small. As of this writing, no archive supports 739 * information on where the file holes are. 740 * Return: 741 * 0 ok, -1 if archive read failure. if we cannot write the entire file, 742 * we return a 0 but "left" is set to be the amount unwritten 743 */ 744 745#if __STDC__ 746int 747rd_wrfile(ARCHD *arcn, int ofd, off_t *left) 748#else 749int 750rd_wrfile(arcn, ofd, left) 751 ARCHD *arcn; 752 int ofd; 753 off_t *left; 754#endif 755{ 756 int cnt = 0; 757 off_t size = arcn->sb.st_size; 758 int res = 0; 759 char *fnm = arcn->name; 760 int isem = 1; 761 int rem; 762 int sz = MINFBSZ; 763 struct stat sb; 764 u_long crc = 0L; 765 766 /* 767 * pass the blocksize of the file being written to the write routine, 768 * if the size is zero, use the default MINFBSZ 769 */ 770 if (fstat(ofd, &sb) == 0) { 771 if (sb.st_blksize > 0) 772 sz = (int)sb.st_blksize; 773 } else 774 syswarn(0,errno,"Unable to obtain block size for file %s",fnm); 775 rem = sz; 776 *left = 0L; 777 778 /* 779 * Copy the archive to the file the number of bytes specified. We have 780 * to assume that we want to recover file holes as none of the archive 781 * formats can record the location of file holes. 782 */ 783 while (size > 0L) { 784 cnt = bufend - bufpt; 785 /* 786 * if we get a read error, we do not want to skip, as we may 787 * miss a header, so we do not set left, but if we get a write 788 * error, we do want to skip over the unprocessed data. 789 */ 790 if ((cnt <= 0) && ((cnt = buf_fill()) <= 0)) 791 break; 792 cnt = MIN(cnt, size); 793 if ((res = file_write(ofd,bufpt,cnt,&rem,&isem,sz,fnm)) <= 0) { 794 *left = size; 795 break; 796 } 797 798 if (docrc) { 799 /* 800 * update the actual crc value 801 */ 802 cnt = res; 803 while (--cnt >= 0) 804 crc += *bufpt++ & 0xff; 805 } else 806 bufpt += res; 807 size -= res; 808 } 809 810 /* 811 * if the last block has a file hole (all zero), we must make sure this 812 * gets updated in the file. We force the last block of zeros to be 813 * written. just closing with the file offset moved foward may not put 814 * a hole at the end of the file. 815 */ 816 if (isem && (arcn->sb.st_size > 0L)) 817 file_flush(ofd, fnm, isem); 818 819 /* 820 * if we failed from archive read, we do not want to skip 821 */ 822 if ((size > 0L) && (*left == 0L)) 823 return(-1); 824 825 /* 826 * some formats record a crc on file data. If so, then we compare the 827 * calculated crc to the crc stored in the archive 828 */ 829 if (docrc && (size == 0L) && (arcn->crc != crc)) 830 tty_warn(1,"Actual crc does not match expected crc %s", 831 arcn->name); 832 return(0); 833} 834 835/* 836 * cp_file() 837 * copy the contents of one file to another. used during -rw phase of pax 838 * just as in rd_wrfile() we use a special write function to write the 839 * destination file so we can properly copy files with holes. 840 */ 841 842#if __STDC__ 843void 844cp_file(ARCHD *arcn, int fd1, int fd2) 845#else 846void 847cp_file(arcn, fd1, fd2) 848 ARCHD *arcn; 849 int fd1; 850 int fd2; 851#endif 852{ 853 int cnt; 854 off_t cpcnt = 0L; 855 int res = 0; 856 char *fnm = arcn->name; 857 int no_hole = 0; 858 int isem = 1; 859 int rem; 860 int sz = MINFBSZ; 861 struct stat sb; 862 863 /* 864 * check for holes in the source file. If none, we will use regular 865 * write instead of file write. 866 */ 867 if (((off_t)(arcn->sb.st_blocks * BLKMULT)) >= arcn->sb.st_size) 868 ++no_hole; 869 870 /* 871 * pass the blocksize of the file being written to the write routine, 872 * if the size is zero, use the default MINFBSZ 873 */ 874 if (fstat(fd2, &sb) == 0) { 875 if (sb.st_blksize > 0) 876 sz = sb.st_blksize; 877 } else 878 syswarn(0,errno,"Unable to obtain block size for file %s",fnm); 879 rem = sz; 880 881 /* 882 * read the source file and copy to destination file until EOF 883 */ 884 for(;;) { 885 if ((cnt = read(fd1, buf, blksz)) <= 0) 886 break; 887 if (no_hole) 888 res = write(fd2, buf, cnt); 889 else 890 res = file_write(fd2, buf, cnt, &rem, &isem, sz, fnm); 891 if (res != cnt) 892 break; 893 cpcnt += cnt; 894 } 895 896 /* 897 * check to make sure the copy is valid. 898 */ 899 if (res < 0) 900 syswarn(1, errno, "Failed write during copy of %s to %s", 901 arcn->org_name, arcn->name); 902 else if (cpcnt != arcn->sb.st_size) 903 tty_warn(1, "File %s changed size during copy to %s", 904 arcn->org_name, arcn->name); 905 else if (fstat(fd1, &sb) < 0) 906 syswarn(1, errno, "Failed stat of %s", arcn->org_name); 907 else if (arcn->sb.st_mtime != sb.st_mtime) 908 tty_warn(1, "File %s was modified during copy to %s", 909 arcn->org_name, arcn->name); 910 911 /* 912 * if the last block has a file hole (all zero), we must make sure this 913 * gets updated in the file. We force the last block of zeros to be 914 * written. just closing with the file offset moved foward may not put 915 * a hole at the end of the file. 916 */ 917 if (!no_hole && isem && (arcn->sb.st_size > 0L)) 918 file_flush(fd2, fnm, isem); 919 return; 920} 921 922/* 923 * buf_fill() 924 * fill the read buffer with the next record (or what we can get) from 925 * the archive volume. 926 * Return: 927 * Number of bytes of data in the read buffer, -1 for read error, and 928 * 0 when finished (user specified termination in ar_next()). 929 */ 930 931#if __STDC__ 932int 933buf_fill(void) 934#else 935int 936buf_fill() 937#endif 938{ 939 int cnt; 940 static int fini = 0; 941 942 if (fini) 943 return(0); 944 945 for(;;) { 946 /* 947 * try to fill the buffer. on error the next archive volume is 948 * opened and we try again. 949 */ 950 if ((cnt = ar_read(buf, blksz)) > 0) { 951 bufpt = buf; 952 bufend = buf + cnt; 953 rdcnt += cnt; 954 return(cnt); 955 } 956 957 /* 958 * errors require resync, EOF goes to next archive 959 */ 960 if (cnt < 0) 961 break; 962 if (ar_next() < 0) { 963 fini = 1; 964 return(0); 965 } 966 rdcnt = 0; 967 } 968 exit_val = 1; 969 return(-1); 970} 971 972/* 973 * buf_flush() 974 * force the write buffer to the archive. We are passed the number of 975 * bytes in the buffer at the point of the flush. When we change archives 976 * the record size might change. (either larger or smaller). 977 * Return: 978 * 0 if all is ok, -1 when a write error occurs. 979 */ 980 981#if __STDC__ 982int 983buf_flush(int bufcnt) 984#else 985int 986buf_flush(bufcnt) 987 int bufcnt; 988#endif 989{ 990 int cnt; 991 int push = 0; 992 int totcnt = 0; 993 994 /* 995 * if we have reached the user specified byte count for each archive 996 * volume, prompt for the next volume. (The non-standrad -R flag). 997 * NOTE: If the wrlimit is smaller than wrcnt, we will always write 998 * at least one record. We always round limit UP to next blocksize. 999 */ 1000 if ((wrlimit > 0) && (wrcnt > wrlimit)) { 1001 tty_warn(0, 1002 "User specified archive volume byte limit reached."); 1003 if (ar_next() < 0) { 1004 wrcnt = 0; 1005 exit_val = 1; 1006 return(-1); 1007 } 1008 wrcnt = 0; 1009 1010 /* 1011 * The new archive volume might have changed the size of the 1012 * write blocksize. if so we figure out if we need to write 1013 * (one or more times), or if there is now free space left in 1014 * the buffer (it is no longer full). bufcnt has the number of 1015 * bytes in the buffer, (the blocksize, at the point we were 1016 * CALLED). Push has the amount of "extra" data in the buffer 1017 * if the block size has shrunk from a volume change. 1018 */ 1019 bufend = buf + blksz; 1020 if (blksz > bufcnt) 1021 return(0); 1022 if (blksz < bufcnt) 1023 push = bufcnt - blksz; 1024 } 1025 1026 /* 1027 * We have enough data to write at least one archive block 1028 */ 1029 for (;;) { 1030 /* 1031 * write a block and check if it all went out ok 1032 */ 1033 cnt = ar_write(buf, blksz); 1034 if (cnt == blksz) { 1035 /* 1036 * the write went ok 1037 */ 1038 wrcnt += cnt; 1039 totcnt += cnt; 1040 if (push > 0) { 1041 /* we have extra data to push to the front. 1042 * check for more than 1 block of push, and if 1043 * so we loop back to write again 1044 */ 1045 memcpy(buf, bufend, push); 1046 bufpt = buf + push; 1047 if (push >= blksz) { 1048 push -= blksz; 1049 continue; 1050 } 1051 } else 1052 bufpt = buf; 1053 return(totcnt); 1054 } else if (cnt > 0) { 1055 /* 1056 * Oh drat we got a partial write! 1057 * if format doesnt care about alignment let it go, 1058 * we warned the user in ar_write().... but this means 1059 * the last record on this volume violates pax spec.... 1060 */ 1061 totcnt += cnt; 1062 wrcnt += cnt; 1063 bufpt = buf + cnt; 1064 cnt = bufcnt - cnt; 1065 memcpy(buf, bufpt, cnt); 1066 bufpt = buf + cnt; 1067 if (!frmt->blkalgn || ((cnt % frmt->blkalgn) == 0)) 1068 return(totcnt); 1069 break; 1070 } 1071 1072 /* 1073 * All done, go to next archive 1074 */ 1075 wrcnt = 0; 1076 if (ar_next() < 0) 1077 break; 1078 1079 /* 1080 * The new archive volume might also have changed the block 1081 * size. if so, figure out if we have too much or too little 1082 * data for using the new block size 1083 */ 1084 bufend = buf + blksz; 1085 if (blksz > bufcnt) 1086 return(0); 1087 if (blksz < bufcnt) 1088 push = bufcnt - blksz; 1089 } 1090 1091 /* 1092 * write failed, stop pax. we must not create a bad archive! 1093 */ 1094 exit_val = 1; 1095 return(-1); 1096} 1097