Index: head/sbin/dump/tape.c =================================================================== --- head/sbin/dump/tape.c (revision 362556) +++ head/sbin/dump/tape.c (revision 362557) @@ -1,887 +1,887 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1980, 1991, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef lint #if 0 static char sccsid[] = "@(#)tape.c 8.4 (Berkeley) 5/1/95"; #endif static const char rcsid[] = "$FreeBSD$"; #endif /* not lint */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "dump.h" ino_t curino; /* current inumber; used globally */ int newtape; /* new tape flag */ union u_spcl u_spcl; /* mapping of variables in a control block */ static int tapefd; /* tape file descriptor */ static long asize; /* number of 0.1" units written on cur tape */ static int writesize; /* size of malloc()ed buffer for tape */ static int64_t lastspclrec = -1; /* tape block number of last written header */ static int trecno = 0; /* next record to write in current block */ static long blocksthisvol; /* number of blocks on current output file */ static char *nexttape; static FILE *popenfp = NULL; static int atomic(ssize_t (*)(), int, char *, int); static void worker(int, int); -static void enworker(void); +static void create_workers(void); static void flushtape(void); static void killall(void); static void rollforward(void); /* * Concurrent dump mods (Caltech) - disk block reading and tape writing * are exported to several worker processes. While one worker writes the * tape, the others read disk blocks; they pass control of the tape in * a ring via signals. The parent process traverses the file system and * sends writeheader()'s and lists of daddr's to the workers via pipes. * The following structure defines the instruction packets sent to workers. */ struct req { ufs2_daddr_t dblk; int count; }; static int reqsiz; #define WORKERS 3 /* 1 worker writing, 1 reading, 1 for slack */ static struct worker { int64_t tapea; /* header number at start of this chunk */ int64_t firstrec; /* record number of this block */ int count; /* count to next header (used for TS_TAPE */ /* after EOT) */ int inode; /* inode that we are currently dealing with */ int fd; /* FD for this worker */ int pid; /* PID for this worker */ int sent; /* 1 == we've sent this worker requests */ char (*tblock)[TP_BSIZE]; /* buffer for data blocks */ struct req *req; /* buffer for requests */ } workers[WORKERS+1]; -static struct worker *mlp; +static struct worker *wp; static char (*nextblock)[TP_BSIZE]; static int master; /* pid of master, for sending error signals */ static int tenths; /* length of tape used per block written */ static volatile sig_atomic_t caught; /* have we caught the signal to proceed? */ static volatile sig_atomic_t ready; /* reached the lock point without having */ /* received the SIGUSR2 signal from the prev worker? */ static jmp_buf jmpbuf; /* where to jump to if we are ready when the */ /* SIGUSR2 arrives from the previous worker */ int alloctape(void) { int pgoff = getpagesize() - 1; char *buf; int i; writesize = ntrec * TP_BSIZE; reqsiz = (ntrec + 1) * sizeof(struct req); /* * CDC 92181's and 92185's make 0.8" gaps in 1600-bpi start/stop mode * (see DEC TU80 User's Guide). The shorter gaps of 6250-bpi require * repositioning after stopping, i.e, streaming mode, where the gap is * variable, 0.30" to 0.45". The gap is maximal when the tape stops. */ if (blocksperfile == 0 && !unlimited) tenths = writesize / density + (cartridge ? 16 : density == 625 ? 5 : 8); /* * Allocate tape buffer contiguous with the array of instruction * packets, so flushtape() can write them together with one write(). * Align tape buffer on page boundary to speed up tape write(). */ for (i = 0; i <= WORKERS; i++) { buf = (char *) malloc((unsigned)(reqsiz + writesize + pgoff + TP_BSIZE)); if (buf == NULL) return(0); workers[i].tblock = (char (*)[TP_BSIZE]) (((long)&buf[ntrec + 1] + pgoff) &~ pgoff); workers[i].req = (struct req *)workers[i].tblock - ntrec - 1; } - mlp = &workers[0]; - mlp->count = 1; - mlp->tapea = 0; - mlp->firstrec = 0; - nextblock = mlp->tblock; + wp = &workers[0]; + wp->count = 1; + wp->tapea = 0; + wp->firstrec = 0; + nextblock = wp->tblock; return(1); } void writerec(char *dp, int isspcl) { - mlp->req[trecno].dblk = (ufs2_daddr_t)0; - mlp->req[trecno].count = 1; + wp->req[trecno].dblk = (ufs2_daddr_t)0; + wp->req[trecno].count = 1; /* Can't do a structure assignment due to alignment problems */ bcopy(dp, *(nextblock)++, sizeof (union u_spcl)); if (isspcl) lastspclrec = spcl.c_tapea; trecno++; spcl.c_tapea++; if (trecno >= ntrec) flushtape(); } void dumpblock(ufs2_daddr_t blkno, int size) { int avail, tpblks; ufs2_daddr_t dblkno; dblkno = fsbtodb(sblock, blkno); tpblks = size >> tp_bshift; while ((avail = MIN(tpblks, ntrec - trecno)) > 0) { - mlp->req[trecno].dblk = dblkno; - mlp->req[trecno].count = avail; + wp->req[trecno].dblk = dblkno; + wp->req[trecno].count = avail; trecno += avail; spcl.c_tapea += avail; if (trecno >= ntrec) flushtape(); dblkno += avail << (tp_bshift - dev_bshift); tpblks -= avail; } } int nogripe = 0; void tperror(int signo __unused) { if (pipeout) { msg("write error on %s\n", tape); quit("Cannot recover\n"); /* NOTREACHED */ } msg("write error %ld blocks into volume %d\n", blocksthisvol, tapeno); broadcast("DUMP WRITE ERROR!\n"); if (!query("Do you want to restart?")) dumpabort(0); msg("Closing this volume. Prepare to restart with new media;\n"); msg("this dump volume will be rewritten.\n"); killall(); nogripe = 1; close_rewind(); Exit(X_REWRITE); } void sigpipe(int signo __unused) { quit("Broken pipe\n"); } static void flushtape(void) { int i, blks, got; int64_t lastfirstrec; - int siz = (char *)nextblock - (char *)mlp->req; + int siz = (char *)nextblock - (char *)wp->req; - mlp->req[trecno].count = 0; /* Sentinel */ + wp->req[trecno].count = 0; /* Sentinel */ - if (atomic(write, mlp->fd, (char *)mlp->req, siz) != siz) + if (atomic(write, wp->fd, (char *)wp->req, siz) != siz) quit("error writing command pipe: %s\n", strerror(errno)); - mlp->sent = 1; /* we sent a request, read the response later */ + wp->sent = 1; /* we sent a request, read the response later */ - lastfirstrec = mlp->firstrec; + lastfirstrec = wp->firstrec; - if (++mlp >= &workers[WORKERS]) - mlp = &workers[0]; + if (++wp >= &workers[WORKERS]) + wp = &workers[0]; /* Read results back from next worker */ - if (mlp->sent) { - if (atomic(read, mlp->fd, (char *)&got, sizeof got) + if (wp->sent) { + if (atomic(read, wp->fd, (char *)&got, sizeof got) != sizeof got) { perror(" DUMP: error reading command pipe in master"); dumpabort(0); } - mlp->sent = 0; + wp->sent = 0; /* Check for end of tape */ if (got < writesize) { msg("End of tape detected\n"); /* * Drain the results, don't care what the values were. * If we read them here then trewind won't... */ for (i = 0; i < WORKERS; i++) { if (workers[i].sent) { if (atomic(read, workers[i].fd, (char *)&got, sizeof got) != sizeof got) { perror(" DUMP: error reading command pipe in master"); dumpabort(0); } workers[i].sent = 0; } } close_rewind(); rollforward(); return; } } blks = 0; if (spcl.c_type != TS_END && spcl.c_type != TS_CLRI && spcl.c_type != TS_BITS) { assert(spcl.c_count <= TP_NINDIR); for (i = 0; i < spcl.c_count; i++) if (spcl.c_addr[i] != 0) blks++; } - mlp->count = lastspclrec + blks + 1 - spcl.c_tapea; - mlp->tapea = spcl.c_tapea; - mlp->firstrec = lastfirstrec + ntrec; - mlp->inode = curino; - nextblock = mlp->tblock; + wp->count = lastspclrec + blks + 1 - spcl.c_tapea; + wp->tapea = spcl.c_tapea; + wp->firstrec = lastfirstrec + ntrec; + wp->inode = curino; + nextblock = wp->tblock; trecno = 0; asize += tenths; blockswritten += ntrec; blocksthisvol += ntrec; if (!pipeout && !unlimited && (blocksperfile ? (blocksthisvol >= blocksperfile) : (asize > tsize))) { close_rewind(); startnewtape(0); } timeest(); } void trewind(void) { struct stat sb; int f; int got; for (f = 0; f < WORKERS; f++) { /* * Drain the results, but unlike EOT we DO (or should) care * what the return values were, since if we detect EOT after * we think we've written the last blocks to the tape anyway, * we have to replay those blocks with rollforward. * * fixme: punt for now. */ if (workers[f].sent) { if (atomic(read, workers[f].fd, (char *)&got, sizeof got) != sizeof got) { perror(" DUMP: error reading command pipe in master"); dumpabort(0); } workers[f].sent = 0; if (got != writesize) { msg("EOT detected in last 2 tape records!\n"); msg("Use a longer tape, decrease the size estimate\n"); quit("or use no size estimate at all.\n"); } } (void) close(workers[f].fd); } while (wait((int *)NULL) >= 0) /* wait for any signals from workers */ /* void */; if (pipeout) return; msg("Closing %s\n", tape); if (popenout) { tapefd = -1; (void)pclose(popenfp); popenfp = NULL; return; } #ifdef RDUMP if (host) { rmtclose(); while (rmtopen(tape, 0) < 0) sleep(10); rmtclose(); return; } #endif if (fstat(tapefd, &sb) == 0 && S_ISFIFO(sb.st_mode)) { (void)close(tapefd); return; } (void) close(tapefd); while ((f = open(tape, 0)) < 0) sleep (10); (void) close(f); } void close_rewind() { time_t tstart_changevol, tend_changevol; trewind(); if (nexttape) return; (void)time((time_t *)&(tstart_changevol)); if (!nogripe) { msg("Change Volumes: Mount volume #%d\n", tapeno+1); broadcast("CHANGE DUMP VOLUMES!\a\a\n"); } while (!query("Is the new volume mounted and ready to go?")) if (query("Do you want to abort?")) { dumpabort(0); /*NOTREACHED*/ } (void)time((time_t *)&(tend_changevol)); if ((tstart_changevol != (time_t)-1) && (tend_changevol != (time_t)-1)) tstart_writing += (tend_changevol - tstart_changevol); } void rollforward(void) { struct req *p, *q, *prev; - struct worker *tmlp; + struct worker *twp; int i, size, got; int64_t savedtapea; union u_spcl *ntb, *otb; - tmlp = &workers[WORKERS]; - ntb = (union u_spcl *)tmlp->tblock[1]; + twp = &workers[WORKERS]; + ntb = (union u_spcl *)twp->tblock[1]; /* * Each of the N workers should have requests that need to * be replayed on the next tape. Use the extra worker buffers * (workers[WORKERS]) to construct request lists to be sent to * each worker in turn. */ for (i = 0; i < WORKERS; i++) { - q = &tmlp->req[1]; - otb = (union u_spcl *)mlp->tblock; + q = &twp->req[1]; + otb = (union u_spcl *)wp->tblock; /* - * For each request in the current worker, copy it to tmlp. + * For each request in the current worker, copy it to twp. */ prev = NULL; - for (p = mlp->req; p->count > 0; p += p->count) { + for (p = wp->req; p->count > 0; p += p->count) { *q = *p; if (p->dblk == 0) *ntb++ = *otb++; /* copy the datablock also */ prev = q; q += q->count; } if (prev == NULL) quit("rollforward: protocol botch"); if (prev->dblk != 0) prev->count -= 1; else ntb--; q -= 1; q->count = 0; - q = &tmlp->req[0]; + q = &twp->req[0]; if (i == 0) { q->dblk = 0; q->count = 1; trecno = 0; - nextblock = tmlp->tblock; + nextblock = twp->tblock; savedtapea = spcl.c_tapea; - spcl.c_tapea = mlp->tapea; + spcl.c_tapea = wp->tapea; startnewtape(0); spcl.c_tapea = savedtapea; lastspclrec = savedtapea - 1; } size = (char *)ntb - (char *)q; - if (atomic(write, mlp->fd, (char *)q, size) != size) { + if (atomic(write, wp->fd, (char *)q, size) != size) { perror(" DUMP: error writing command pipe"); dumpabort(0); } - mlp->sent = 1; - if (++mlp >= &workers[WORKERS]) - mlp = &workers[0]; + wp->sent = 1; + if (++wp >= &workers[WORKERS]) + wp = &workers[0]; q->count = 1; if (prev->dblk != 0) { /* * If the last one was a disk block, make the * first of this one be the last bit of that disk * block... */ q->dblk = prev->dblk + prev->count * (TP_BSIZE / DEV_BSIZE); - ntb = (union u_spcl *)tmlp->tblock; + ntb = (union u_spcl *)twp->tblock; } else { /* * It wasn't a disk block. Copy the data to its * new location in the buffer. */ q->dblk = 0; - *((union u_spcl *)tmlp->tblock) = *ntb; - ntb = (union u_spcl *)tmlp->tblock[1]; + *((union u_spcl *)twp->tblock) = *ntb; + ntb = (union u_spcl *)twp->tblock[1]; } } - mlp->req[0] = *q; - nextblock = mlp->tblock; + wp->req[0] = *q; + nextblock = wp->tblock; if (q->dblk == 0) nextblock++; trecno = 1; /* * Clear the first workers' response. One hopes that it * worked ok, otherwise the tape is much too short! */ - if (mlp->sent) { - if (atomic(read, mlp->fd, (char *)&got, sizeof got) + if (wp->sent) { + if (atomic(read, wp->fd, (char *)&got, sizeof got) != sizeof got) { perror(" DUMP: error reading command pipe in master"); dumpabort(0); } - mlp->sent = 0; + wp->sent = 0; if (got != writesize) { quit("EOT detected at start of the tape!\n"); } } } /* * We implement taking and restoring checkpoints on the tape level. * When each tape is opened, a new process is created by forking; this * saves all of the necessary context in the parent. The child * continues the dump; the parent waits around, saving the context. * If the child returns X_REWRITE, then it had problems writing that tape; * this causes the parent to fork again, duplicating the context, and * everything continues as if nothing had happened. */ void startnewtape(int top) { int parentpid; int childpid; int status; char *p; sig_t interrupt_save; interrupt_save = signal(SIGINT, SIG_IGN); parentpid = getpid(); restore_check_point: (void)signal(SIGINT, interrupt_save); /* * All signals are inherited... */ setproctitle(NULL); /* Restore the proctitle. */ childpid = fork(); if (childpid < 0) { msg("Context save fork fails in parent %d\n", parentpid); Exit(X_ABORT); } if (childpid != 0) { /* * PARENT: * save the context by waiting * until the child doing all of the work returns. * don't catch the interrupt */ signal(SIGINT, SIG_IGN); #ifdef TDEBUG msg("Tape: %d; parent process: %d child process %d\n", tapeno+1, parentpid, childpid); #endif /* TDEBUG */ if (waitpid(childpid, &status, 0) == -1) msg("Waiting for child %d: %s\n", childpid, strerror(errno)); if (status & 0xFF) { msg("Child %d returns LOB status %o\n", childpid, status&0xFF); } status = (status >> 8) & 0xFF; #ifdef TDEBUG switch(status) { case X_FINOK: msg("Child %d finishes X_FINOK\n", childpid); break; case X_ABORT: msg("Child %d finishes X_ABORT\n", childpid); break; case X_REWRITE: msg("Child %d finishes X_REWRITE\n", childpid); break; default: msg("Child %d finishes unknown %d\n", childpid, status); break; } #endif /* TDEBUG */ switch(status) { case X_FINOK: Exit(X_FINOK); case X_ABORT: Exit(X_ABORT); case X_REWRITE: goto restore_check_point; default: msg("Bad return code from dump: %d\n", status); Exit(X_ABORT); } /*NOTREACHED*/ } else { /* we are the child; just continue */ #ifdef TDEBUG sleep(4); /* allow time for parent's message to get out */ msg("Child on Tape %d has parent %d, my pid = %d\n", tapeno+1, parentpid, getpid()); #endif /* TDEBUG */ /* * If we have a name like "/dev/rmt0,/dev/rmt1", * use the name before the comma first, and save * the remaining names for subsequent volumes. */ tapeno++; /* current tape sequence */ if (nexttape || strchr(tape, ',')) { if (nexttape && *nexttape) tape = nexttape; if ((p = strchr(tape, ',')) != NULL) { *p = '\0'; nexttape = p + 1; } else nexttape = NULL; msg("Dumping volume %d on %s\n", tapeno, tape); } if (pipeout) { tapefd = STDOUT_FILENO; } else if (popenout) { char volno[sizeof("2147483647")]; (void)sprintf(volno, "%d", spcl.c_volume + 1); if (setenv("DUMP_VOLUME", volno, 1) == -1) { msg("Cannot set $DUMP_VOLUME.\n"); dumpabort(0); } popenfp = popen(popenout, "w"); if (popenfp == NULL) { msg("Cannot open output pipeline \"%s\".\n", popenout); dumpabort(0); } tapefd = fileno(popenfp); } else { #ifdef RDUMP while ((tapefd = (host ? rmtopen(tape, 2) : open(tape, O_WRONLY|O_CREAT, 0666))) < 0) #else while ((tapefd = open(tape, O_WRONLY|O_CREAT, 0666)) < 0) #endif { msg("Cannot open output \"%s\".\n", tape); if (!query("Do you want to retry the open?")) dumpabort(0); } } - enworker(); /* Share open tape file descriptor with workers */ + create_workers(); /* Share open tape file descriptor with workers */ if (popenout) close(tapefd); /* Give up our copy of it. */ signal(SIGINFO, infosch); asize = 0; blocksthisvol = 0; if (top) newtape++; /* new tape signal */ - spcl.c_count = mlp->count; + spcl.c_count = wp->count; /* * measure firstrec in TP_BSIZE units since restore doesn't * know the correct ntrec value... */ - spcl.c_firstrec = mlp->firstrec; + spcl.c_firstrec = wp->firstrec; spcl.c_volume++; spcl.c_type = TS_TAPE; - writeheader((ino_t)mlp->inode); + writeheader((ino_t)wp->inode); if (tapeno > 1) msg("Volume %d begins with blocks from inode %d\n", - tapeno, mlp->inode); + tapeno, wp->inode); } } void dumpabort(int signo __unused) { if (master != 0 && master != getpid()) /* Signals master to call dumpabort */ (void) kill(master, SIGTERM); else { killall(); msg("The ENTIRE dump is aborted.\n"); } #ifdef RDUMP rmtclose(); #endif Exit(X_ABORT); } void Exit(status) int status; { #ifdef TDEBUG msg("pid = %d exits with status %d\n", getpid(), status); #endif /* TDEBUG */ exit(status); } /* * proceed - handler for SIGUSR2, used to synchronize IO between the workers. */ void proceed(int signo __unused) { if (ready) longjmp(jmpbuf, 1); caught++; } void -enworker(void) +create_workers(void) { int cmd[2]; int i, j; master = getpid(); signal(SIGTERM, dumpabort); /* Worker sends SIGTERM on dumpabort() */ signal(SIGPIPE, sigpipe); signal(SIGUSR1, tperror); /* Worker sends SIGUSR1 on tape errors */ signal(SIGUSR2, proceed); /* Worker sends SIGUSR2 to next worker */ for (i = 0; i < WORKERS; i++) { - if (i == mlp - &workers[0]) { + if (i == wp - &workers[0]) { caught = 1; } else { caught = 0; } if (socketpair(AF_UNIX, SOCK_STREAM, 0, cmd) < 0 || (workers[i].pid = fork()) < 0) quit("too many workers, %d (recompile smaller): %s\n", i, strerror(errno)); workers[i].fd = cmd[1]; workers[i].sent = 0; if (workers[i].pid == 0) { /* Worker starts up here */ for (j = 0; j <= i; j++) (void) close(workers[j].fd); signal(SIGINT, SIG_IGN); /* Master handles this */ worker(cmd[0], i); Exit(X_FINOK); } } for (i = 0; i < WORKERS; i++) (void) atomic(write, workers[i].fd, (char *) &workers[(i + 1) % WORKERS].pid, sizeof workers[0].pid); master = 0; } void killall(void) { int i; for (i = 0; i < WORKERS; i++) if (workers[i].pid > 0) { (void) kill(workers[i].pid, SIGKILL); workers[i].sent = 0; } } /* * Synchronization - each process has a lockfile, and shares file * descriptors to the following process's lockfile. When our write * completes, we release our lock on the following process's lock- * file, allowing the following process to lock it and proceed. We * get the lock back for the next cycle by swapping descriptors. */ static void worker(int cmd, int worker_number) { int nread; int nextworker, size, wrote, eot_count; /* * Need our own seek pointer. */ (void) close(diskfd); if ((diskfd = open(disk, O_RDONLY)) < 0) quit("worker couldn't reopen disk: %s\n", strerror(errno)); /* * Need the pid of the next worker in the loop... */ if ((nread = atomic(read, cmd, (char *)&nextworker, sizeof nextworker)) != sizeof nextworker) { quit("master/worker protocol botched - didn't get pid of next worker.\n"); } /* * Get list of blocks to dump, read the blocks into tape buffer */ - while ((nread = atomic(read, cmd, (char *)mlp->req, reqsiz)) == reqsiz) { - struct req *p = mlp->req; + while ((nread = atomic(read, cmd, (char *)wp->req, reqsiz)) == reqsiz) { + struct req *p = wp->req; for (trecno = 0; trecno < ntrec; trecno += p->count, p += p->count) { if (p->dblk) { - blkread(p->dblk, mlp->tblock[trecno], + blkread(p->dblk, wp->tblock[trecno], p->count * TP_BSIZE); } else { if (p->count != 1 || atomic(read, cmd, - (char *)mlp->tblock[trecno], + (char *)wp->tblock[trecno], TP_BSIZE) != TP_BSIZE) quit("master/worker protocol botched.\n"); } } if (setjmp(jmpbuf) == 0) { ready = 1; if (!caught) (void) pause(); } ready = 0; caught = 0; /* Try to write the data... */ eot_count = 0; size = 0; wrote = 0; while (eot_count < 10 && size < writesize) { #ifdef RDUMP if (host) - wrote = rmtwrite(mlp->tblock[0]+size, + wrote = rmtwrite(wp->tblock[0]+size, writesize-size); else #endif - wrote = write(tapefd, mlp->tblock[0]+size, + wrote = write(tapefd, wp->tblock[0]+size, writesize-size); #ifdef WRITEDEBUG printf("worker %d wrote %d\n", worker_number, wrote); #endif if (wrote < 0) break; if (wrote == 0) eot_count++; size += wrote; } #ifdef WRITEDEBUG if (size != writesize) printf("worker %d only wrote %d out of %d bytes and gave up.\n", worker_number, size, writesize); #endif /* * Handle ENOSPC as an EOT condition. */ if (wrote < 0 && errno == ENOSPC) { wrote = 0; eot_count++; } if (eot_count > 0) size = 0; if (wrote < 0) { (void) kill(master, SIGUSR1); for (;;) (void) sigpause(0); } else { /* * pass size of write back to master * (for EOT handling) */ (void) atomic(write, cmd, (char *)&size, sizeof size); } /* * If partial write, don't want next worker to go. * Also jolts him awake. */ (void) kill(nextworker, SIGUSR2); } if (nread != 0) quit("error reading command pipe: %s\n", strerror(errno)); } /* * Since a read from a pipe may not return all we asked for, * or a write may not write all we ask if we get a signal, * loop until the count is satisfied (or error). */ static int atomic(ssize_t (*func)(), int fd, char *buf, int count) { int got, need = count; while ((got = (*func)(fd, buf, need)) > 0 && (need -= got) > 0) buf += got; return (got < 0 ? got : count - need); }