1 /*- 2 * Copyright (c) 1980, 1991 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #ifndef lint 9 static char sccsid[] = "@(#)tape.c 5.27 (Berkeley) 05/11/93"; 10 #endif /* not lint */ 11 12 #include <sys/param.h> 13 #include <sys/socket.h> 14 #include <sys/time.h> 15 #include <sys/wait.h> 16 #ifdef sunos 17 #include <sys/vnode.h> 18 19 #include <ufs/fs.h> 20 #include <ufs/inode.h> 21 #else 22 #include <ufs/ffs/fs.h> 23 #include <ufs/ufs/dinode.h> 24 #endif 25 26 #include <protocols/dumprestore.h> 27 28 #include <errno.h> 29 #include <fcntl.h> 30 #include <setjmp.h> 31 #include <signal.h> 32 #include <stdio.h> 33 #ifdef __STDC__ 34 #include <stdlib.h> 35 #include <string.h> 36 #include <unistd.h> 37 #else 38 int write(), read(); 39 #endif 40 41 #include "dump.h" 42 #include "pathnames.h" 43 44 int writesize; /* size of malloc()ed buffer for tape */ 45 long lastspclrec = -1; /* tape block number of last written header */ 46 int trecno = 0; /* next record to write in current block */ 47 extern long blocksperfile; /* number of blocks per output file */ 48 long blocksthisvol; /* number of blocks on current output file */ 49 extern int ntrec; /* blocking factor on tape */ 50 extern int cartridge; 51 extern char *host; 52 char *nexttape; 53 54 static int atomic __P((int (*)(), int, char *, int)); 55 static void doslave __P((int, int)); 56 static void enslave __P((void)); 57 static void flushtape __P((void)); 58 static void killall __P((void)); 59 static void rollforward __P((void)); 60 61 /* 62 * Concurrent dump mods (Caltech) - disk block reading and tape writing 63 * are exported to several slave processes. While one slave writes the 64 * tape, the others read disk blocks; they pass control of the tape in 65 * a ring via signals. The parent process traverses the filesystem and 66 * sends writeheader()'s and lists of daddr's to the slaves via pipes. 67 * The following structure defines the instruction packets sent to slaves. 68 */ 69 struct req { 70 daddr_t dblk; 71 int count; 72 }; 73 int reqsiz; 74 75 #define SLAVES 3 /* 1 slave writing, 1 reading, 1 for slack */ 76 struct slave { 77 int tapea; /* header number at start of this chunk */ 78 int count; /* count to next header (used for TS_TAPE */ 79 /* after EOT) */ 80 int inode; /* inode that we are currently dealing with */ 81 int fd; /* FD for this slave */ 82 int pid; /* PID for this slave */ 83 int sent; /* 1 == we've sent this slave requests */ 84 int firstrec; /* record number of this block */ 85 char (*tblock)[TP_BSIZE]; /* buffer for data blocks */ 86 struct req *req; /* buffer for requests */ 87 } slaves[SLAVES+1]; 88 struct slave *slp; 89 90 char (*nextblock)[TP_BSIZE]; 91 92 int master; /* pid of master, for sending error signals */ 93 int tenths; /* length of tape used per block written */ 94 static int caught; /* have we caught the signal to proceed? */ 95 static int ready; /* have we reached the lock point without having */ 96 /* received the SIGUSR2 signal from the prev slave? */ 97 static jmp_buf jmpbuf; /* where to jump to if we are ready when the */ 98 /* SIGUSR2 arrives from the previous slave */ 99 100 int 101 alloctape() 102 { 103 int pgoff = getpagesize() - 1; 104 char *buf; 105 int i; 106 107 writesize = ntrec * TP_BSIZE; 108 reqsiz = (ntrec + 1) * sizeof(struct req); 109 /* 110 * CDC 92181's and 92185's make 0.8" gaps in 1600-bpi start/stop mode 111 * (see DEC TU80 User's Guide). The shorter gaps of 6250-bpi require 112 * repositioning after stopping, i.e, streaming mode, where the gap is 113 * variable, 0.30" to 0.45". The gap is maximal when the tape stops. 114 */ 115 if (blocksperfile == 0) 116 tenths = writesize / density + 117 (cartridge ? 16 : density == 625 ? 5 : 8); 118 /* 119 * Allocate tape buffer contiguous with the array of instruction 120 * packets, so flushtape() can write them together with one write(). 121 * Align tape buffer on page boundary to speed up tape write(). 122 */ 123 for (i = 0; i <= SLAVES; i++) { 124 buf = (char *) 125 malloc((unsigned)(reqsiz + writesize + pgoff + TP_BSIZE)); 126 if (buf == NULL) 127 return(0); 128 slaves[i].tblock = (char (*)[TP_BSIZE]) 129 (((long)&buf[ntrec + 1] + pgoff) &~ pgoff); 130 slaves[i].req = (struct req *)slaves[i].tblock - ntrec - 1; 131 } 132 slp = &slaves[0]; 133 slp->count = 1; 134 slp->tapea = 0; 135 slp->firstrec = 0; 136 nextblock = slp->tblock; 137 return(1); 138 } 139 140 void 141 writerec(dp, isspcl) 142 char *dp; 143 int isspcl; 144 { 145 146 slp->req[trecno].dblk = (daddr_t)0; 147 slp->req[trecno].count = 1; 148 *(union u_spcl *)(*(nextblock)++) = *(union u_spcl *)dp; 149 if (isspcl) 150 lastspclrec = spcl.c_tapea; 151 trecno++; 152 spcl.c_tapea++; 153 if (trecno >= ntrec) 154 flushtape(); 155 } 156 157 void 158 dumpblock(blkno, size) 159 daddr_t blkno; 160 int size; 161 { 162 int avail, tpblks, dblkno; 163 164 dblkno = fsbtodb(sblock, blkno); 165 tpblks = size >> tp_bshift; 166 while ((avail = MIN(tpblks, ntrec - trecno)) > 0) { 167 slp->req[trecno].dblk = dblkno; 168 slp->req[trecno].count = avail; 169 trecno += avail; 170 spcl.c_tapea += avail; 171 if (trecno >= ntrec) 172 flushtape(); 173 dblkno += avail << (tp_bshift - dev_bshift); 174 tpblks -= avail; 175 } 176 } 177 178 int nogripe = 0; 179 180 void 181 tperror(signo) 182 int signo; 183 { 184 185 if (pipeout) { 186 msg("write error on %s\n", tape); 187 quit("Cannot recover\n"); 188 /* NOTREACHED */ 189 } 190 msg("write error %d blocks into volume %d\n", blocksthisvol, tapeno); 191 broadcast("DUMP WRITE ERROR!\n"); 192 if (!query("Do you want to restart?")) 193 dumpabort(0); 194 msg("Closing this volume. Prepare to restart with new media;\n"); 195 msg("this dump volume will be rewritten.\n"); 196 killall(); 197 nogripe = 1; 198 close_rewind(); 199 Exit(X_REWRITE); 200 } 201 202 void 203 sigpipe(signo) 204 int signo; 205 { 206 207 quit("Broken pipe\n"); 208 } 209 210 static void 211 flushtape() 212 { 213 int i, blks, got; 214 long lastfirstrec; 215 216 int siz = (char *)nextblock - (char *)slp->req; 217 218 slp->req[trecno].count = 0; /* Sentinel */ 219 220 if (atomic(write, slp->fd, (char *)slp->req, siz) != siz) 221 quit("error writing command pipe: %s\n", strerror(errno)); 222 slp->sent = 1; /* we sent a request, read the response later */ 223 224 lastfirstrec = slp->firstrec; 225 226 if (++slp >= &slaves[SLAVES]) 227 slp = &slaves[0]; 228 229 /* Read results back from next slave */ 230 if (slp->sent) { 231 if (atomic(read, slp->fd, (char *)&got, sizeof got) 232 != sizeof got) { 233 perror(" DUMP: error reading command pipe in master"); 234 dumpabort(0); 235 } 236 slp->sent = 0; 237 238 /* Check for end of tape */ 239 if (got < writesize) { 240 msg("End of tape detected\n"); 241 242 /* 243 * Drain the results, don't care what the values were. 244 * If we read them here then trewind won't... 245 */ 246 for (i = 0; i < SLAVES; i++) { 247 if (slaves[i].sent) { 248 if (atomic(read, slaves[i].fd, 249 (char *)&got, sizeof got) 250 != sizeof got) { 251 perror(" DUMP: error reading command pipe in master"); 252 dumpabort(0); 253 } 254 slaves[i].sent = 0; 255 } 256 } 257 258 close_rewind(); 259 rollforward(); 260 return; 261 } 262 } 263 264 blks = 0; 265 if (spcl.c_type != TS_END) { 266 for (i = 0; i < spcl.c_count; i++) 267 if (spcl.c_addr[i] != 0) 268 blks++; 269 } 270 slp->count = lastspclrec + blks + 1 - spcl.c_tapea; 271 slp->tapea = spcl.c_tapea; 272 slp->firstrec = lastfirstrec + ntrec; 273 slp->inode = curino; 274 nextblock = slp->tblock; 275 trecno = 0; 276 asize += tenths; 277 blockswritten += ntrec; 278 blocksthisvol += ntrec; 279 if (!pipeout && (blocksperfile ? 280 (blocksthisvol >= blocksperfile) : (asize > tsize))) { 281 close_rewind(); 282 startnewtape(0); 283 } 284 timeest(); 285 } 286 287 void 288 trewind() 289 { 290 int f; 291 int got; 292 293 for (f = 0; f < SLAVES; f++) { 294 /* 295 * Drain the results, but unlike EOT we DO (or should) care 296 * what the return values were, since if we detect EOT after 297 * we think we've written the last blocks to the tape anyway, 298 * we have to replay those blocks with rollforward. 299 * 300 * fixme: punt for now. 301 */ 302 if (slaves[f].sent) { 303 if (atomic(read, slaves[f].fd, (char *)&got, sizeof got) 304 != sizeof got) { 305 perror(" DUMP: error reading command pipe in master"); 306 dumpabort(0); 307 } 308 slaves[f].sent = 0; 309 if (got != writesize) { 310 msg("EOT detected in last 2 tape records!\n"); 311 msg("Use a longer tape, decrease the size estimate\n"); 312 quit("or use no size estimate at all.\n"); 313 } 314 } 315 (void) close(slaves[f].fd); 316 } 317 while (wait((int *)NULL) >= 0) /* wait for any signals from slaves */ 318 /* void */; 319 320 if (pipeout) 321 return; 322 323 msg("Closing %s\n", tape); 324 325 #ifdef RDUMP 326 if (host) { 327 rmtclose(); 328 while (rmtopen(tape, 0) < 0) 329 sleep(10); 330 rmtclose(); 331 return; 332 } 333 #endif 334 (void) close(tapefd); 335 while ((f = open(tape, 0)) < 0) 336 sleep (10); 337 (void) close(f); 338 } 339 340 void 341 close_rewind() 342 { 343 trewind(); 344 if (nexttape) 345 return; 346 if (!nogripe) { 347 msg("Change Volumes: Mount volume #%d\n", tapeno+1); 348 broadcast("CHANGE DUMP VOLUMES!\7\7\n"); 349 } 350 while (!query("Is the new volume mounted and ready to go?")) 351 if (query("Do you want to abort?")) { 352 dumpabort(0); 353 /*NOTREACHED*/ 354 } 355 } 356 357 void 358 rollforward() 359 { 360 register struct req *p, *q, *prev; 361 register struct slave *tslp; 362 int i, size, savedtapea, got; 363 union u_spcl *ntb, *otb; 364 tslp = &slaves[SLAVES]; 365 ntb = (union u_spcl *)tslp->tblock[1]; 366 367 /* 368 * Each of the N slaves should have requests that need to 369 * be replayed on the next tape. Use the extra slave buffers 370 * (slaves[SLAVES]) to construct request lists to be sent to 371 * each slave in turn. 372 */ 373 for (i = 0; i < SLAVES; i++) { 374 q = &tslp->req[1]; 375 otb = (union u_spcl *)slp->tblock; 376 377 /* 378 * For each request in the current slave, copy it to tslp. 379 */ 380 381 prev = NULL; 382 for (p = slp->req; p->count > 0; p += p->count) { 383 *q = *p; 384 if (p->dblk == 0) 385 *ntb++ = *otb++; /* copy the datablock also */ 386 prev = q; 387 q += q->count; 388 } 389 if (prev == NULL) 390 quit("rollforward: protocol botch"); 391 if (prev->dblk != 0) 392 prev->count -= 1; 393 else 394 ntb--; 395 q -= 1; 396 q->count = 0; 397 q = &tslp->req[0]; 398 if (i == 0) { 399 q->dblk = 0; 400 q->count = 1; 401 trecno = 0; 402 nextblock = tslp->tblock; 403 savedtapea = spcl.c_tapea; 404 spcl.c_tapea = slp->tapea; 405 startnewtape(0); 406 spcl.c_tapea = savedtapea; 407 lastspclrec = savedtapea - 1; 408 } 409 size = (char *)ntb - (char *)q; 410 if (atomic(write, slp->fd, (char *)q, size) != size) { 411 perror(" DUMP: error writing command pipe"); 412 dumpabort(0); 413 } 414 slp->sent = 1; 415 if (++slp >= &slaves[SLAVES]) 416 slp = &slaves[0]; 417 418 q->count = 1; 419 420 if (prev->dblk != 0) { 421 /* 422 * If the last one was a disk block, make the 423 * first of this one be the last bit of that disk 424 * block... 425 */ 426 q->dblk = prev->dblk + 427 prev->count * (TP_BSIZE / DEV_BSIZE); 428 ntb = (union u_spcl *)tslp->tblock; 429 } else { 430 /* 431 * It wasn't a disk block. Copy the data to its 432 * new location in the buffer. 433 */ 434 q->dblk = 0; 435 *((union u_spcl *)tslp->tblock) = *ntb; 436 ntb = (union u_spcl *)tslp->tblock[1]; 437 } 438 } 439 slp->req[0] = *q; 440 nextblock = slp->tblock; 441 if (q->dblk == 0) 442 nextblock++; 443 trecno = 1; 444 445 /* 446 * Clear the first slaves' response. One hopes that it 447 * worked ok, otherwise the tape is much too short! 448 */ 449 if (slp->sent) { 450 if (atomic(read, slp->fd, (char *)&got, sizeof got) 451 != sizeof got) { 452 perror(" DUMP: error reading command pipe in master"); 453 dumpabort(0); 454 } 455 slp->sent = 0; 456 457 if (got != writesize) { 458 quit("EOT detected at start of the tape!\n"); 459 } 460 } 461 } 462 463 /* 464 * We implement taking and restoring checkpoints on the tape level. 465 * When each tape is opened, a new process is created by forking; this 466 * saves all of the necessary context in the parent. The child 467 * continues the dump; the parent waits around, saving the context. 468 * If the child returns X_REWRITE, then it had problems writing that tape; 469 * this causes the parent to fork again, duplicating the context, and 470 * everything continues as if nothing had happened. 471 */ 472 void 473 startnewtape(top) 474 int top; 475 { 476 int parentpid; 477 int childpid; 478 int status; 479 int waitpid; 480 char *p; 481 #ifdef sunos 482 void (*interrupt_save)(); 483 #else 484 sig_t interrupt_save; 485 #endif 486 487 interrupt_save = signal(SIGINT, SIG_IGN); 488 parentpid = getpid(); 489 490 restore_check_point: 491 (void)signal(SIGINT, interrupt_save); 492 /* 493 * All signals are inherited... 494 */ 495 childpid = fork(); 496 if (childpid < 0) { 497 msg("Context save fork fails in parent %d\n", parentpid); 498 Exit(X_ABORT); 499 } 500 if (childpid != 0) { 501 /* 502 * PARENT: 503 * save the context by waiting 504 * until the child doing all of the work returns. 505 * don't catch the interrupt 506 */ 507 signal(SIGINT, SIG_IGN); 508 #ifdef TDEBUG 509 msg("Tape: %d; parent process: %d child process %d\n", 510 tapeno+1, parentpid, childpid); 511 #endif /* TDEBUG */ 512 while ((waitpid = wait(&status)) != childpid) 513 msg("Parent %d waiting for child %d has another child %d return\n", 514 parentpid, childpid, waitpid); 515 if (status & 0xFF) { 516 msg("Child %d returns LOB status %o\n", 517 childpid, status&0xFF); 518 } 519 status = (status >> 8) & 0xFF; 520 #ifdef TDEBUG 521 switch(status) { 522 case X_FINOK: 523 msg("Child %d finishes X_FINOK\n", childpid); 524 break; 525 case X_ABORT: 526 msg("Child %d finishes X_ABORT\n", childpid); 527 break; 528 case X_REWRITE: 529 msg("Child %d finishes X_REWRITE\n", childpid); 530 break; 531 default: 532 msg("Child %d finishes unknown %d\n", 533 childpid, status); 534 break; 535 } 536 #endif /* TDEBUG */ 537 switch(status) { 538 case X_FINOK: 539 Exit(X_FINOK); 540 case X_ABORT: 541 Exit(X_ABORT); 542 case X_REWRITE: 543 goto restore_check_point; 544 default: 545 msg("Bad return code from dump: %d\n", status); 546 Exit(X_ABORT); 547 } 548 /*NOTREACHED*/ 549 } else { /* we are the child; just continue */ 550 #ifdef TDEBUG 551 sleep(4); /* allow time for parent's message to get out */ 552 msg("Child on Tape %d has parent %d, my pid = %d\n", 553 tapeno+1, parentpid, getpid()); 554 #endif /* TDEBUG */ 555 /* 556 * If we have a name like "/dev/rmt0,/dev/rmt1", 557 * use the name before the comma first, and save 558 * the remaining names for subsequent volumes. 559 */ 560 tapeno++; /* current tape sequence */ 561 if (nexttape || index(tape, ',')) { 562 if (nexttape && *nexttape) 563 tape = nexttape; 564 if ((p = index(tape, ',')) != NULL) { 565 *p = '\0'; 566 nexttape = p + 1; 567 } else 568 nexttape = NULL; 569 msg("Dumping volume %d on %s\n", tapeno, tape); 570 } 571 #ifdef RDUMP 572 while ((tapefd = (host ? rmtopen(tape, 2) : 573 pipeout ? 1 : open(tape, O_WRONLY|O_CREAT, 0666))) < 0) 574 #else 575 while ((tapefd = (pipeout ? 1 : 576 open(tape, O_WRONLY|O_CREAT, 0666))) < 0) 577 #endif 578 { 579 msg("Cannot open output \"%s\".\n", tape); 580 if (!query("Do you want to retry the open?")) 581 dumpabort(0); 582 } 583 584 enslave(); /* Share open tape file descriptor with slaves */ 585 586 asize = 0; 587 blocksthisvol = 0; 588 if (top) 589 newtape++; /* new tape signal */ 590 spcl.c_count = slp->count; 591 /* 592 * measure firstrec in TP_BSIZE units since restore doesn't 593 * know the correct ntrec value... 594 */ 595 spcl.c_firstrec = slp->firstrec; 596 spcl.c_volume++; 597 spcl.c_type = TS_TAPE; 598 spcl.c_flags |= DR_NEWHEADER; 599 writeheader((ino_t)slp->inode); 600 spcl.c_flags &=~ DR_NEWHEADER; 601 if (tapeno > 1) 602 msg("Volume %d begins with blocks from inode %d\n", 603 tapeno, slp->inode); 604 } 605 } 606 607 void 608 dumpabort(signo) 609 int signo; 610 { 611 612 if (master != 0 && master != getpid()) 613 /* Signals master to call dumpabort */ 614 (void) kill(master, SIGTERM); 615 else { 616 killall(); 617 msg("The ENTIRE dump is aborted.\n"); 618 } 619 Exit(X_ABORT); 620 } 621 622 __dead void 623 Exit(status) 624 int status; 625 { 626 627 #ifdef TDEBUG 628 msg("pid = %d exits with status %d\n", getpid(), status); 629 #endif /* TDEBUG */ 630 exit(status); 631 } 632 633 /* 634 * proceed - handler for SIGUSR2, used to synchronize IO between the slaves. 635 */ 636 void 637 proceed(signo) 638 int signo; 639 { 640 641 if (ready) 642 longjmp(jmpbuf, 1); 643 caught++; 644 } 645 646 void 647 enslave() 648 { 649 int cmd[2]; 650 register int i, j; 651 652 master = getpid(); 653 654 signal(SIGTERM, dumpabort); /* Slave sends SIGTERM on dumpabort() */ 655 signal(SIGPIPE, sigpipe); 656 signal(SIGUSR1, tperror); /* Slave sends SIGUSR1 on tape errors */ 657 signal(SIGUSR2, proceed); /* Slave sends SIGUSR2 to next slave */ 658 659 for (i = 0; i < SLAVES; i++) { 660 if (i == slp - &slaves[0]) { 661 caught = 1; 662 } else { 663 caught = 0; 664 } 665 666 if (socketpair(AF_UNIX, SOCK_STREAM, 0, cmd) < 0 || 667 (slaves[i].pid = fork()) < 0) 668 quit("too many slaves, %d (recompile smaller): %s\n", 669 i, strerror(errno)); 670 671 slaves[i].fd = cmd[1]; 672 slaves[i].sent = 0; 673 if (slaves[i].pid == 0) { /* Slave starts up here */ 674 for (j = 0; j <= i; j++) 675 (void) close(slaves[j].fd); 676 signal(SIGINT, SIG_IGN); /* Master handles this */ 677 doslave(cmd[0], i); 678 Exit(X_FINOK); 679 } 680 } 681 682 for (i = 0; i < SLAVES; i++) 683 (void) atomic(write, slaves[i].fd, 684 (char *) &slaves[(i + 1) % SLAVES].pid, 685 sizeof slaves[0].pid); 686 687 master = 0; 688 } 689 690 void 691 killall() 692 { 693 register int i; 694 695 for (i = 0; i < SLAVES; i++) 696 if (slaves[i].pid > 0) 697 (void) kill(slaves[i].pid, SIGKILL); 698 } 699 700 /* 701 * Synchronization - each process has a lockfile, and shares file 702 * descriptors to the following process's lockfile. When our write 703 * completes, we release our lock on the following process's lock- 704 * file, allowing the following process to lock it and proceed. We 705 * get the lock back for the next cycle by swapping descriptors. 706 */ 707 static void 708 doslave(cmd, slave_number) 709 register int cmd; 710 int slave_number; 711 { 712 register int nread; 713 int nextslave, size, wrote, eot_count; 714 715 /* 716 * Need our own seek pointer. 717 */ 718 (void) close(diskfd); 719 if ((diskfd = open(disk, O_RDONLY)) < 0) 720 quit("slave couldn't reopen disk: %s\n", strerror(errno)); 721 722 /* 723 * Need the pid of the next slave in the loop... 724 */ 725 if ((nread = atomic(read, cmd, (char *)&nextslave, sizeof nextslave)) 726 != sizeof nextslave) { 727 quit("master/slave protocol botched - didn't get pid of next slave.\n"); 728 } 729 730 /* 731 * Get list of blocks to dump, read the blocks into tape buffer 732 */ 733 while ((nread = atomic(read, cmd, (char *)slp->req, reqsiz)) == reqsiz) { 734 register struct req *p = slp->req; 735 736 for (trecno = 0; trecno < ntrec; 737 trecno += p->count, p += p->count) { 738 if (p->dblk) { 739 bread(p->dblk, slp->tblock[trecno], 740 p->count * TP_BSIZE); 741 } else { 742 if (p->count != 1 || atomic(read, cmd, 743 (char *)slp->tblock[trecno], 744 TP_BSIZE) != TP_BSIZE) 745 quit("master/slave protocol botched.\n"); 746 } 747 } 748 if (setjmp(jmpbuf) == 0) { 749 ready = 1; 750 if (!caught) 751 (void) pause(); 752 } 753 ready = 0; 754 caught = 0; 755 756 /* Try to write the data... */ 757 eot_count = 0; 758 size = 0; 759 760 while (eot_count < 10 && size < writesize) { 761 #ifdef RDUMP 762 if (host) 763 wrote = rmtwrite(slp->tblock[0]+size, 764 writesize-size); 765 else 766 #endif 767 wrote = write(tapefd, slp->tblock[0]+size, 768 writesize-size); 769 #ifdef WRITEDEBUG 770 printf("slave %d wrote %d\n", slave_number, wrote); 771 #endif 772 if (wrote < 0) 773 break; 774 if (wrote == 0) 775 eot_count++; 776 size += wrote; 777 } 778 779 #ifdef WRITEDEBUG 780 if (size != writesize) 781 printf("slave %d only wrote %d out of %d bytes and gave up.\n", 782 slave_number, size, writesize); 783 #endif 784 785 if (eot_count > 0) 786 size = 0; 787 788 /* 789 * fixme: Pyramids running OSx return ENOSPC 790 * at EOT on 1/2 inch drives. 791 */ 792 if (size < 0) { 793 (void) kill(master, SIGUSR1); 794 for (;;) 795 (void) sigpause(0); 796 } else { 797 /* 798 * pass size of write back to master 799 * (for EOT handling) 800 */ 801 (void) atomic(write, cmd, (char *)&size, sizeof size); 802 } 803 804 /* 805 * If partial write, don't want next slave to go. 806 * Also jolts him awake. 807 */ 808 (void) kill(nextslave, SIGUSR2); 809 } 810 if (nread != 0) 811 quit("error reading command pipe: %s\n", strerror(errno)); 812 } 813 814 /* 815 * Since a read from a pipe may not return all we asked for, 816 * or a write may not write all we ask if we get a signal, 817 * loop until the count is satisfied (or error). 818 */ 819 static int 820 atomic(func, fd, buf, count) 821 int (*func)(), fd; 822 char *buf; 823 int count; 824 { 825 int got, need = count; 826 827 while ((got = (*func)(fd, buf, need)) > 0 && (need -= got) > 0) 828 buf += got; 829 return (got < 0 ? got : count - need); 830 } 831