sbin/dump/tape.c

   1 /*-
   2  * Copyright (c) 1980, 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)tape.c   8.4 (Berkeley) 5/1/95
  30  * $FreeBSD: src/sbin/dump/tape.c,v 1.12.2.3 2002/02/23 22:32:51 iedowse Exp $
  31  */
  32
  33 #include <sys/param.h>
  34 #include <sys/socket.h>
  35 #include <sys/time.h>
  36 #include <sys/wait.h>
  37 #include <sys/stat.h>
  38 #include <vfs/ufs/dinode.h>
  39 #include <vfs/ufs/fs.h>
  40
  41 #include <protocols/dumprestore.h>
  42
  43 #include <errno.h>
  44 #include <fcntl.h>
  45 #include <setjmp.h>
  46 #include <signal.h>
  47 #include <stdio.h>
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include <unistd.h>
  51
  52 #include "dump.h"
  53
  54 static int writesize;           /* size of malloc()ed buffer for tape */
  55 static long lastspclrec = -1;   /* tape block number of last written header */
  56 static int trecno = 0;          /* next record to write in current block */
  57 static long blocksthisvol;              /* number of blocks on current output file */
  58 static const char       *nexttape;
  59 static int tapeno = 0;  /* current tape number */
  60
  61 static int      atomic_read(int, void *, int);
  62 static int      atomic_write(int, const void *, int);
  63 #ifdef WRITEDEBUG
  64 static void     doslave(int, int);
  65 #else
  66 static void     doslave(int);
  67 #endif
  68 static void     enslave(void);
  69 static void     flushtape(void);
  70 static void     killall(void);
  71 static void     rollforward(void);
  72
  73 /*
  74  * Concurrent dump mods (Caltech) - disk block reading and tape writing
  75  * are exported to several slave processes.  While one slave writes the
  76  * tape, the others read disk blocks; they pass control of the tape in
  77  * a ring via signals. The parent process traverses the filesystem and
  78  * sends writeheader()'s and lists of daddr's to the slaves via pipes.
  79  * The following structure defines the instruction packets sent to slaves.
  80  */
  81 struct req {
  82         daddr_t dblk;
  83         int count;
  84 };
  85 int reqsiz;
  86
  87 #define SLAVES 3                /* 1 slave writing, 1 reading, 1 for slack */
  88 struct slave {
  89         int tapea;              /* header number at start of this chunk */
  90         int count;              /* count to next header (used for TS_TAPE */
  91                                 /* after EOT) */
  92         int inode;              /* inode that we are currently dealing with */
  93         int fd;                 /* FD for this slave */
  94         int pid;                /* PID for this slave */
  95         int sent;               /* 1 == we've sent this slave requests */
  96         int firstrec;           /* record number of this block */
  97         char (*tblock)[TP_BSIZE]; /* buffer for data blocks */
  98         struct req *req;        /* buffer for requests */
  99 } slaves[SLAVES+1];
 100 struct slave *slp;
 101
 102 char    (*nextblock)[TP_BSIZE];
 103
 104 int master;             /* pid of master, for sending error signals */
 105 int tenths;             /* length of tape used per block written */
 106 static int caught;      /* have we caught the signal to proceed? */
 107 static int ready;       /* have we reached the lock point without having */
 108                         /* received the SIGUSR2 signal from the prev slave? */
 109 static jmp_buf jmpbuf;  /* where to jump to if we are ready when the */
 110                         /* SIGUSR2 arrives from the previous slave */
 111
 112 int
 113 alloctape(void)
 114 {
 115         int pgoff = getpagesize() - 1;
 116         char *buf;
 117         int i;
 118
 119         writesize = ntrec * TP_BSIZE;
 120         reqsiz = (ntrec + 1) * sizeof(struct req);
 121         /*
 122          * CDC 92181's and 92185's make 0.8" gaps in 1600-bpi start/stop mode
 123          * (see DEC TU80 User's Guide).  The shorter gaps of 6250-bpi require
 124          * repositioning after stopping, i.e, streaming mode, where the gap is
 125          * variable, 0.30" to 0.45".  The gap is maximal when the tape stops.
 126          */
 127         if (blocksperfile == 0 && !unlimited)
 128                 tenths = writesize / density +
 129                     (cartridge ? 16 : density == 625 ? 5 : 8);
 130         /*
 131          * Allocate tape buffer contiguous with the array of instruction
 132          * packets, so flushtape() can write them together with one write().
 133          * Align tape buffer on page boundary to speed up tape write().
 134          */
 135         for (i = 0; i <= SLAVES; i++) {
 136                 buf = (char *)
 137                     malloc((unsigned)(reqsiz + writesize + pgoff + TP_BSIZE));
 138                 if (buf == NULL)
 139                         return(0);
 140                 slaves[i].tblock = (char (*)[TP_BSIZE])
 141                     (((long)&buf[ntrec + 1] + pgoff) &~ pgoff);
 142                 slaves[i].req = (struct req *)slaves[i].tblock - ntrec - 1;
 143         }
 144         slp = &slaves[0];
 145         slp->count = 1;
 146         slp->tapea = 0;
 147         slp->firstrec = 0;
 148         nextblock = slp->tblock;
 149         return(1);
 150 }
 151
 152 void
 153 writerec(const void *dp, int isspcl)
 154 {
 155
 156         slp->req[trecno].dblk = (daddr_t)0;
 157         slp->req[trecno].count = 1;
 158         bcopy(dp, *(nextblock)++, sizeof (union u_spcl));
 159         if (isspcl)
 160                 lastspclrec = spcl.c_tapea;
 161         trecno++;
 162         spcl.c_tapea++;
 163         if (trecno >= ntrec)
 164                 flushtape();
 165 }
 166
 167 void
 168 dumpblock(daddr_t blkno, int size)
 169 {
 170         int avail, tpblks, dblkno;
 171
 172         dblkno = fsbtodb(sblock, blkno);
 173         tpblks = size >> tp_bshift;
 174         while ((avail = MIN(tpblks, ntrec - trecno)) > 0) {
 175                 slp->req[trecno].dblk = dblkno;
 176                 slp->req[trecno].count = avail;
 177                 trecno += avail;
 178                 spcl.c_tapea += avail;
 179                 if (trecno >= ntrec)
 180                         flushtape();
 181                 dblkno += avail << (tp_bshift - dev_bshift);
 182                 tpblks -= avail;
 183         }
 184 }
 185
 186 int     nogripe = 0;
 187
 188 static void
 189 tperror(int signo __unused)
 190 {
 191
 192         if (pipeout) {
 193                 msg("write error on %s\n", tape);
 194                 quit("Cannot recover\n");
 195                 /* NOTREACHED */
 196         }
 197         msg("write error %ld blocks into volume %d\n", blocksthisvol, tapeno);
 198         broadcast("DUMP WRITE ERROR!\n");
 199         if (!query("Do you want to restart?"))
 200                 dumpabort(0);
 201         msg("Closing this volume.  Prepare to restart with new media;\n");
 202         msg("this dump volume will be rewritten.\n");
 203         killall();
 204         nogripe = 1;
 205         close_rewind();
 206         Exit(X_REWRITE);
 207 }
 208
 209 static void
 210 sigpipe(int signo __unused)
 211 {
 212
 213         quit("Broken pipe\n");
 214 }
 215
 216 static void
 217 flushtape(void)
 218 {
 219         int i, blks, got;
 220         long lastfirstrec;
 221
 222         int siz = (char *)nextblock - (char *)slp->req;
 223
 224         slp->req[trecno].count = 0;                     /* Sentinel */
 225
 226         if (atomic_write(slp->fd, slp->req, siz) != siz)
 227                 quit("error writing command pipe: %s\n", strerror(errno));
 228         slp->sent = 1; /* we sent a request, read the response later */
 229
 230         lastfirstrec = slp->firstrec;
 231
 232         if (++slp >= &slaves[SLAVES])
 233                 slp = &slaves[0];
 234
 235         /* Read results back from next slave */
 236         if (slp->sent) {
 237                 if (atomic_read(slp->fd, &got, sizeof got)
 238                     != sizeof got) {
 239                         perror("  DUMP: error reading command pipe in master");
 240                         dumpabort(0);
 241                 }
 242                 slp->sent = 0;
 243
 244                 /* Check for end of tape */
 245                 if (got < writesize) {
 246                         msg("End of tape detected\n");
 247
 248                         /*
 249                          * Drain the results, don't care what the values were.
 250                          * If we read them here then trewind won't...
 251                          */
 252                         for (i = 0; i < SLAVES; i++) {
 253                                 if (slaves[i].sent) {
 254                                         if (atomic_read(slaves[i].fd,
 255                                             &got, sizeof got)
 256                                             != sizeof got) {
 257                                                 perror("  DUMP: error reading command pipe in master");
 258                                                 dumpabort(0);
 259                                         }
 260                                         slaves[i].sent = 0;
 261                                 }
 262                         }
 263
 264                         close_rewind();
 265                         rollforward();
 266                         return;
 267                 }
 268         }
 269
 270         blks = 0;
 271         if (spcl.c_type != TS_END) {
 272                 for (i = 0; i < spcl.c_count; i++)
 273                         if (spcl.c_addr[i] != 0)
 274                                 blks++;
 275         }
 276         slp->count = lastspclrec + blks + 1 - spcl.c_tapea;
 277         slp->tapea = spcl.c_tapea;
 278         slp->firstrec = lastfirstrec + ntrec;
 279         slp->inode = curino;
 280         nextblock = slp->tblock;
 281         trecno = 0;
 282         asize += tenths;
 283         blockswritten += ntrec;
 284         blocksthisvol += ntrec;
 285         if (!pipeout && !unlimited && (blocksperfile ?
 286             (blocksthisvol >= blocksperfile) : (asize > tsize))) {
 287                 close_rewind();
 288                 startnewtape(0);
 289         }
 290         timeest();
 291 }
 292
 293 void
 294 trewind(void)
 295 {
 296         struct stat sb;
 297         int f;
 298         int got;
 299
 300         for (f = 0; f < SLAVES; f++) {
 301                 /*
 302                  * Drain the results, but unlike EOT we DO (or should) care
 303                  * what the return values were, since if we detect EOT after
 304                  * we think we've written the last blocks to the tape anyway,
 305                  * we have to replay those blocks with rollforward.
 306                  *
 307                  * fixme: punt for now.
 308                  */
 309                 if (slaves[f].sent) {
 310                         if (atomic_read(slaves[f].fd, &got, sizeof got)
 311                             != sizeof got) {
 312                                 perror("  DUMP: error reading command pipe in master");
 313                                 dumpabort(0);
 314                         }
 315                         slaves[f].sent = 0;
 316                         if (got != writesize) {
 317                                 msg("EOT detected in last 2 tape records!\n");
 318                                 msg("Use a longer tape, decrease the size estimate\n");
 319                                 quit("or use no size estimate at all.\n");
 320                         }
 321                 }
 322                 close(slaves[f].fd);
 323         }
 324         while (wait(NULL) >= 0) /* wait for any signals from slaves */
 325                 /* void */;
 326
 327         if (pipeout)
 328                 return;
 329
 330         msg("Closing %s\n", tape);
 331
 332 #ifdef RDUMP
 333         if (host) {
 334                 rmtclose();
 335                 while (rmtopen(tape, 0) < 0)
 336                         sleep(10);
 337                 rmtclose();
 338                 return;
 339         }
 340 #endif
 341         if (fstat(tapefd, &sb) == 0 && S_ISFIFO(sb.st_mode)) {
 342                 close(tapefd);
 343                 return;
 344         }
 345         close(tapefd);
 346         while ((f = open(tape, 0)) < 0)
 347                 sleep (10);
 348         close(f);
 349 }
 350
 351 void
 352 close_rewind(void)
 353 {
 354         time_t tstart_changevol, tend_changevol;
 355
 356         trewind();
 357         if (nexttape)
 358                 return;
 359         time((time_t *)&(tstart_changevol));
 360         if (!nogripe) {
 361                 msg("Change Volumes: Mount volume #%d\n", tapeno+1);
 362                 broadcast("CHANGE DUMP VOLUMES!\a\a\n");
 363         }
 364         while (!query("Is the new volume mounted and ready to go?"))
 365                 if (query("Do you want to abort?")) {
 366                         dumpabort(0);
 367                         /*NOTREACHED*/
 368                 }
 369         time((time_t *)&(tend_changevol));
 370         if ((tstart_changevol != (time_t)-1) && (tend_changevol != (time_t)-1))
 371                 tstart_writing += (tend_changevol - tstart_changevol);
 372 }
 373
 374 void
 375 rollforward(void)
 376 {
 377         struct req *p, *q, *prev;
 378         struct slave *tslp;
 379         int i, size, savedtapea, got;
 380         union u_spcl *ntb, *otb;
 381         tslp = &slaves[SLAVES];
 382         ntb = (union u_spcl *)tslp->tblock[1];
 383
 384         /*
 385          * Each of the N slaves should have requests that need to
 386          * be replayed on the next tape.  Use the extra slave buffers
 387          * (slaves[SLAVES]) to construct request lists to be sent to
 388          * each slave in turn.
 389          */
 390         for (i = 0; i < SLAVES; i++) {
 391                 q = &tslp->req[1];
 392                 otb = (union u_spcl *)slp->tblock;
 393
 394                 /*
 395                  * For each request in the current slave, copy it to tslp.
 396                  */
 397
 398                 prev = NULL;
 399                 for (p = slp->req; p->count > 0; p += p->count) {
 400                         *q = *p;
 401                         if (p->dblk == 0)
 402                                 *ntb++ = *otb++; /* copy the datablock also */
 403                         prev = q;
 404                         q += q->count;
 405                 }
 406                 if (prev == NULL)
 407                         quit("rollforward: protocol botch");
 408                 if (prev->dblk != 0)
 409                         prev->count -= 1;
 410                 else
 411                         ntb--;
 412                 q -= 1;
 413                 q->count = 0;
 414                 q = &tslp->req[0];
 415                 if (i == 0) {
 416                         q->dblk = 0;
 417                         q->count = 1;
 418                         trecno = 0;
 419                         nextblock = tslp->tblock;
 420                         savedtapea = spcl.c_tapea;
 421                         spcl.c_tapea = slp->tapea;
 422                         startnewtape(0);
 423                         spcl.c_tapea = savedtapea;
 424                         lastspclrec = savedtapea - 1;
 425                 }
 426                 size = (char *)ntb - (char *)q;
 427                 if (atomic_write(slp->fd, q, size) != size) {
 428                         perror("  DUMP: error writing command pipe");
 429                         dumpabort(0);
 430                 }
 431                 slp->sent = 1;
 432                 if (++slp >= &slaves[SLAVES])
 433                         slp = &slaves[0];
 434
 435                 q->count = 1;
 436
 437                 if (prev->dblk != 0) {
 438                         /*
 439                          * If the last one was a disk block, make the
 440                          * first of this one be the last bit of that disk
 441                          * block...
 442                          */
 443                         q->dblk = prev->dblk +
 444                                 prev->count * (TP_BSIZE / DEV_BSIZE);
 445                         ntb = (union u_spcl *)tslp->tblock;
 446                 } else {
 447                         /*
 448                          * It wasn't a disk block.  Copy the data to its
 449                          * new location in the buffer.
 450                          */
 451                         q->dblk = 0;
 452                         *((union u_spcl *)tslp->tblock) = *ntb;
 453                         ntb = (union u_spcl *)tslp->tblock[1];
 454                 }
 455         }
 456         slp->req[0] = *q;
 457         nextblock = slp->tblock;
 458         if (q->dblk == 0)
 459                 nextblock++;
 460         trecno = 1;
 461
 462         /*
 463          * Clear the first slaves' response.  One hopes that it
 464          * worked ok, otherwise the tape is much too short!
 465          */
 466         if (slp->sent) {
 467                 if (atomic_read(slp->fd, &got, sizeof got)
 468                     != sizeof got) {
 469                         perror("  DUMP: error reading command pipe in master");
 470                         dumpabort(0);
 471                 }
 472                 slp->sent = 0;
 473
 474                 if (got != writesize) {
 475                         quit("EOT detected at start of the tape!\n");
 476                 }
 477         }
 478 }
 479
 480 /*
 481  * We implement taking and restoring checkpoints on the tape level.
 482  * When each tape is opened, a new process is created by forking; this
 483  * saves all of the necessary context in the parent.  The child
 484  * continues the dump; the parent waits around, saving the context.
 485  * If the child returns X_REWRITE, then it had problems writing that tape;
 486  * this causes the parent to fork again, duplicating the context, and
 487  * everything continues as if nothing had happened.
 488  */
 489 void
 490 startnewtape(int top)
 491 {
 492         int     parentpid;
 493         int     childpid;
 494         int     status;
 495         int     wait_pid;
 496         char    *p;
 497         sig_t   interrupt_save;
 498
 499         interrupt_save = signal(SIGINT, SIG_IGN);
 500         parentpid = getpid();
 501
 502 restore_check_point:
 503         signal(SIGINT, interrupt_save);
 504         /*
 505          *      All signals are inherited...
 506          */
 507         setproctitle(NULL);     /* Restore the proctitle. */
 508         childpid = fork();
 509         if (childpid < 0) {
 510                 msg("Context save fork fails in parent %d\n", parentpid);
 511                 Exit(X_ABORT);
 512         }
 513         if (childpid != 0) {
 514                 /*
 515                  *      PARENT:
 516                  *      save the context by waiting
 517                  *      until the child doing all of the work returns.
 518                  *      don't catch the interrupt
 519                  */
 520                 signal(SIGINT, SIG_IGN);
 521 #ifdef TDEBUG
 522                 msg("Tape: %d; parent process: %d child process %d\n",
 523                         tapeno+1, parentpid, childpid);
 524 #endif /* TDEBUG */
 525                 while ((wait_pid = wait(&status)) != childpid)
 526                         msg("Parent %d waiting for child %d has another child %d return\n",
 527                                 parentpid, childpid, wait_pid);
 528                 if (status & 0xFF) {
 529                         msg("Child %d returns LOB status %o\n",
 530                                 childpid, status&0xFF);
 531                 }
 532                 status = (status >> 8) & 0xFF;
 533 #ifdef TDEBUG
 534                 switch(status) {
 535                         case X_FINOK:
 536                                 msg("Child %d finishes X_FINOK\n", childpid);
 537                                 break;
 538                         case X_ABORT:
 539                                 msg("Child %d finishes X_ABORT\n", childpid);
 540                                 break;
 541                         case X_REWRITE:
 542                                 msg("Child %d finishes X_REWRITE\n", childpid);
 543                                 break;
 544                         default:
 545                                 msg("Child %d finishes unknown %d\n",
 546                                         childpid, status);
 547                                 break;
 548                 }
 549 #endif /* TDEBUG */
 550                 switch(status) {
 551                         case X_FINOK:
 552                                 Exit(X_FINOK);
 553                         case X_ABORT:
 554                                 Exit(X_ABORT);
 555                         case X_REWRITE:
 556                                 goto restore_check_point;
 557                         default:
 558                                 msg("Bad return code from dump: %d\n", status);
 559                                 Exit(X_ABORT);
 560                 }
 561                 /*NOTREACHED*/
 562         } else {        /* we are the child; just continue */
 563 #ifdef TDEBUG
 564                 sleep(4);       /* allow time for parent's message to get out */
 565                 msg("Child on Tape %d has parent %d, my pid = %d\n",
 566                         tapeno+1, parentpid, getpid());
 567 #endif /* TDEBUG */
 568                 /*
 569                  * If we have a name like "/dev/rmt0,/dev/rmt1",
 570                  * use the name before the comma first, and save
 571                  * the remaining names for subsequent volumes.
 572                  */
 573                 tapeno++;               /* current tape sequence */
 574                 if (nexttape || strchr(tape, ',')) {
 575                         if (nexttape && *nexttape)
 576                                 tape = nexttape;
 577                         if ((p = strchr(tape, ',')) != NULL) {
 578                                 *p = '\0';
 579                                 nexttape = p + 1;
 580                         } else
 581                                 nexttape = NULL;
 582                         msg("Dumping volume %d on %s\n", tapeno, tape);
 583                 }
 584 #ifdef RDUMP
 585                 while ((tapefd = (host ? rmtopen(tape, 2) :
 586                         pipeout ? 1 : open(tape, O_WRONLY|O_CREAT, 0666))) < 0)
 587 #else
 588                 while ((tapefd = (pipeout ? 1 :
 589                                   open(tape, O_WRONLY|O_CREAT, 0666))) < 0)
 590 #endif
 591                     {
 592                         msg("Cannot open output \"%s\".\n", tape);
 593                         if (!query("Do you want to retry the open?"))
 594                                 dumpabort(0);
 595                 }
 596
 597                 enslave();  /* Share open tape file descriptor with slaves */
 598                 signal(SIGINFO, infosch);
 599
 600                 asize = 0;
 601                 blocksthisvol = 0;
 602                 if (top)
 603                         newtape++;              /* new tape signal */
 604                 spcl.c_count = slp->count;
 605                 /*
 606                  * measure firstrec in TP_BSIZE units since restore doesn't
 607                  * know the correct ntrec value...
 608                  */
 609                 spcl.c_firstrec = slp->firstrec;
 610                 spcl.c_volume++;
 611                 spcl.c_type = TS_TAPE;
 612                 spcl.c_flags |= DR_NEWHEADER;
 613                 writeheader((ufs1_ino_t)slp->inode);
 614                 spcl.c_flags &=~ DR_NEWHEADER;
 615                 if (tapeno > 1)
 616                         msg("Volume %d begins with blocks from inode %d\n",
 617                                 tapeno, slp->inode);
 618         }
 619 }
 620
 621 void
 622 dumpabort(int signo __unused)
 623 {
 624
 625         if (master != 0 && master != getpid())
 626                 /* Signals master to call dumpabort */
 627                 kill(master, SIGTERM);
 628         else {
 629                 killall();
 630                 msg("The ENTIRE dump is aborted.\n");
 631         }
 632 #ifdef RDUMP
 633         rmtclose();
 634 #endif
 635         Exit(X_ABORT);
 636 }
 637
 638 void
 639 Exit(int status)
 640 {
 641
 642 #ifdef TDEBUG
 643         msg("pid = %d exits with status %d\n", getpid(), status);
 644 #endif /* TDEBUG */
 645         exit(status);
 646 }
 647
 648 /*
 649  * proceed - handler for SIGUSR2, used to synchronize IO between the slaves.
 650  */
 651 static void
 652 proceed(int signo __unused)
 653 {
 654
 655         if (ready)
 656                 longjmp(jmpbuf, 1);
 657         caught++;
 658 }
 659
 660 static void
 661 enslave(void)
 662 {
 663         int cmd[2];
 664         int i, j;
 665
 666         master = getpid();
 667
 668         signal(SIGTERM, dumpabort);  /* Slave sends SIGTERM on dumpabort() */
 669         signal(SIGPIPE, sigpipe);
 670         signal(SIGUSR1, tperror);    /* Slave sends SIGUSR1 on tape errors */
 671         signal(SIGUSR2, proceed);    /* Slave sends SIGUSR2 to next slave */
 672
 673         for (i = 0; i < SLAVES; i++) {
 674                 if (i == slp - &slaves[0]) {
 675                         caught = 1;
 676                 } else {
 677                         caught = 0;
 678                 }
 679
 680                 if (socketpair(AF_UNIX, SOCK_STREAM, 0, cmd) < 0 ||
 681                     (slaves[i].pid = fork()) < 0)
 682                         quit("too many slaves, %d (recompile smaller): %s\n",
 683                             i, strerror(errno));
 684
 685                 slaves[i].fd = cmd[1];
 686                 slaves[i].sent = 0;
 687                 if (slaves[i].pid == 0) {           /* Slave starts up here */
 688                         for (j = 0; j <= i; j++)
 689                                 close(slaves[j].fd);
 690                         signal(SIGINT, SIG_IGN);    /* Master handles this */
 691 #ifdef WRITEDEBUG
 692                         doslave(cmd[0], i);
 693 #else
 694                         doslave(cmd[0]);
 695 #endif
 696                         Exit(X_FINOK);
 697                 }
 698         }
 699
 700         for (i = 0; i < SLAVES; i++)
 701                 atomic_write(slaves[i].fd, &slaves[(i + 1) % SLAVES].pid,
 702                     sizeof slaves[0].pid);
 703
 704         master = 0;
 705 }
 706
 707 void
 708 killall(void)
 709 {
 710         int i;
 711
 712         for (i = 0; i < SLAVES; i++)
 713                 if (slaves[i].pid > 0) {
 714                         kill(slaves[i].pid, SIGKILL);
 715                         slaves[i].sent = 0;
 716                 }
 717 }
 718
 719 /*
 720  * Synchronization - each process has a lockfile, and shares file
 721  * descriptors to the following process's lockfile.  When our write
 722  * completes, we release our lock on the following process's lock-
 723  * file, allowing the following process to lock it and proceed. We
 724  * get the lock back for the next cycle by swapping descriptors.
 725  */
 726 static void
 727 #ifdef WRITEDEBUG
 728 doslave(int cmd, int slave_number)
 729 #else
 730 doslave(int cmd)
 731 #endif
 732 {
 733         int nread;
 734         int nextslave, size, wrote, eot_count;
 735
 736         /*
 737          * Need our own seek pointer.
 738          */
 739         close(diskfd);
 740         if ((diskfd = open(disk, O_RDONLY)) < 0)
 741                 quit("slave couldn't reopen disk: %s\n", strerror(errno));
 742
 743         /*
 744          * Need the pid of the next slave in the loop...
 745          */
 746         if ((nread = atomic_read(cmd, &nextslave, sizeof nextslave))
 747             != sizeof nextslave) {
 748                 quit("master/slave protocol botched - didn't get pid of next slave.\n");
 749         }
 750
 751         /*
 752          * Get list of blocks to dump, read the blocks into tape buffer
 753          */
 754         while ((nread = atomic_read(cmd, slp->req, reqsiz)) == reqsiz) {
 755                 struct req *p = slp->req;
 756
 757                 for (trecno = 0; trecno < ntrec;
 758                      trecno += p->count, p += p->count) {
 759                         if (p->dblk) {
 760                                 bread(p->dblk, slp->tblock[trecno],
 761                                         p->count * TP_BSIZE);
 762                         } else {
 763                                 if (p->count != 1 ||
 764                                     atomic_read(cmd, slp->tblock[trecno],
 765                                     TP_BSIZE) != TP_BSIZE)
 766                                        quit("master/slave protocol botched.\n");
 767                         }
 768                 }
 769                 if (setjmp(jmpbuf) == 0) {
 770                         ready = 1;
 771                         if (!caught)
 772                                 pause();
 773                 }
 774                 ready = 0;
 775                 caught = 0;
 776
 777                 /* Try to write the data... */
 778                 eot_count = 0;
 779                 size = 0;
 780                 wrote = 0;
 781
 782                 while (eot_count < 10 && size < writesize) {
 783 #ifdef RDUMP
 784                         if (host)
 785                                 wrote = rmtwrite(slp->tblock[0]+size,
 786                                     writesize-size);
 787                         else
 788 #endif
 789                                 wrote = write(tapefd, slp->tblock[0]+size,
 790                                     writesize-size);
 791 #ifdef WRITEDEBUG
 792                         printf("slave %d wrote %d\n", slave_number, wrote);
 793 #endif
 794                         if (wrote < 0)
 795                                 break;
 796                         if (wrote == 0)
 797                                 eot_count++;
 798                         size += wrote;
 799                 }
 800
 801 #ifdef WRITEDEBUG
 802                 if (size != writesize)
 803                  printf("slave %d only wrote %d out of %d bytes and gave up.\n",
 804                      slave_number, size, writesize);
 805 #endif
 806
 807                 /*
 808                  * Handle ENOSPC as an EOT condition.
 809                  */
 810                 if (wrote < 0 && errno == ENOSPC) {
 811                         wrote = 0;
 812                         eot_count++;
 813                 }
 814
 815                 if (eot_count > 0)
 816                         size = 0;
 817
 818                 if (wrote < 0) {
 819                         kill(master, SIGUSR1);
 820                         for (;;)
 821                                 sigpause(0);
 822                 } else {
 823                         /*
 824                          * pass size of write back to master
 825                          * (for EOT handling)
 826                          */
 827                         atomic_write(cmd, &size, sizeof size);
 828                 }
 829
 830                 /*
 831                  * If partial write, don't want next slave to go.
 832                  * Also jolts him awake.
 833                  */
 834                 kill(nextslave, SIGUSR2);
 835         }
 836         if (nread != 0)
 837                 quit("error reading command pipe: %s\n", strerror(errno));
 838 }
 839
 840 static int
 841 atomic_read(int fd, void *buf, int count)
 842 {
 843         int got, need = count;
 844
 845         while ((got = read(fd, buf, need)) > 0 && (need -= got) > 0)
 846                 buf = (uint8_t *)buf + got;
 847         return (got < 0 ? got : count - need);
 848 }
 849
 850 static int
 851 atomic_write(int fd, const void *buf, int count)
 852 {
 853         int got, need = count;
 854
 855         while ((got = write(fd, buf, need)) > 0 && (need -= got) > 0)
 856                 buf = (const uint8_t *)buf + got;
 857         return (got < 0 ? got : count - need);
 858 }