]>
git.wh0rd.org - dump.git/blob - dump/tape.c
2 * Ported to Linux's Second Extended File System as part of the
3 * dump and restore backup suit
4 * Remy Card <card@Linux.EU.Org>, 1994-1997
5 * Stelian Pop <pop@cybercable.fr>, 1999-2000
9 * Copyright (c) 1980, 1991, 1993
10 * The Regents of the University of California. All rights reserved.
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
42 static const char rcsid
[] =
43 "$Id: tape.c,v 1.11 2000/01/21 10:17:41 stelian Exp $";
47 #include <sys/types.h>
48 #include <linux/types.h>
50 #include <sys/param.h>
51 #include <sys/socket.h>
55 #include <linux/ext2_fs.h>
56 #include <bsdcompat.h>
59 #include <sys/vnode.h>
62 #include <ufs/inode.h>
64 #include <ufs/ufs/dinode.h>
65 #include <ufs/ffs/fs.h>
67 #endif /* __linux__ */
69 #include <protocols/dumprestore.h>
85 #include <ext2fs/ext2fs.h>
90 int writesize
; /* size of malloc()ed buffer for tape */
91 long lastspclrec
= -1; /* tape block number of last written header */
92 int trecno
= 0; /* next record to write in current block */
93 extern long blocksperfile
; /* number of blocks per output file */
94 long blocksthisvol
; /* number of blocks on current output file */
95 extern int ntrec
; /* blocking factor on tape */
101 static ssize_t atomic_read
__P((int, void *, size_t));
102 static ssize_t atomic_write
__P((int, const void *, size_t));
103 static void doslave
__P((int, int));
104 static void enslave
__P((void));
105 static void flushtape
__P((void));
106 static void killall
__P((void));
107 static void rollforward
__P((void));
110 * Concurrent dump mods (Caltech) - disk block reading and tape writing
111 * are exported to several slave processes. While one slave writes the
112 * tape, the others read disk blocks; they pass control of the tape in
113 * a ring via signals. The parent process traverses the filesystem and
114 * sends writeheader()'s and lists of daddr's to the slaves via pipes.
115 * The following structure defines the instruction packets sent to slaves.
123 #define SLAVES 3 /* 1 slave writing, 1 reading, 1 for slack */
125 int tapea
; /* header number at start of this chunk */
126 int count
; /* count to next header (used for TS_TAPE */
128 int inode
; /* inode that we are currently dealing with */
129 int fd
; /* FD for this slave */
130 int pid
; /* PID for this slave */
131 int sent
; /* 1 == we've sent this slave requests */
132 int firstrec
; /* record number of this block */
133 char (*tblock
)[TP_BSIZE
]; /* buffer for data blocks */
134 struct req
*req
; /* buffer for requests */
138 char (*nextblock
)[TP_BSIZE
];
140 static time_t tstart_volume
; /* time of volume start */
141 static int tapea_volume
; /* value of spcl.c_tapea at volume start */
143 int master
; /* pid of master, for sending error signals */
144 int tenths
; /* length of tape used per block written */
145 static int caught
; /* have we caught the signal to proceed? */
146 static int ready
; /* have we reached the lock point without having */
147 /* received the SIGUSR2 signal from the prev slave? */
148 static sigjmp_buf jmpbuf
; /* where to jump to if we are ready when the */
149 /* SIGUSR2 arrives from the previous slave */
154 int pgoff
= getpagesize() - 1;
158 writesize
= ntrec
* TP_BSIZE
;
159 reqsiz
= (ntrec
+ 1) * sizeof(struct req
);
161 * CDC 92181's and 92185's make 0.8" gaps in 1600-bpi start/stop mode
162 * (see DEC TU80 User's Guide). The shorter gaps of 6250-bpi require
163 * repositioning after stopping, i.e, streaming mode, where the gap is
164 * variable, 0.30" to 0.45". The gap is maximal when the tape stops.
166 if (blocksperfile
== 0 && !unlimited
)
167 tenths
= writesize
/ density
+
168 (cartridge
? 16 : density
== 625 ? 5 : 8);
170 * Allocate tape buffer contiguous with the array of instruction
171 * packets, so flushtape() can write them together with one write().
172 * Align tape buffer on page boundary to speed up tape write().
174 for (i
= 0; i
<= SLAVES
; i
++) {
176 malloc((unsigned)(reqsiz
+ writesize
+ pgoff
+ TP_BSIZE
));
179 slaves
[i
].tblock
= (char (*)[TP_BSIZE
])
181 (((long)&buf
[reqsiz
] + pgoff
) &~ pgoff
);
183 (((long)&buf
[ntrec
+ 1] + pgoff
) &~ pgoff
);
185 slaves
[i
].req
= (struct req
*)slaves
[i
].tblock
- ntrec
- 1;
191 nextblock
= slp
->tblock
;
196 writerec(const void *dp
, int isspcl
)
199 slp
->req
[trecno
].dblk
= (daddr_t
)0;
200 slp
->req
[trecno
].count
= 1;
201 /* XXX post increment triggers an egcs-1.1.2-12 bug on alpha/sparc */
202 *(union u_spcl
*)(*(nextblock
)) = *(union u_spcl
*)dp
;
205 lastspclrec
= spcl
.c_tapea
;
213 dumpblock(daddr_t blkno
, int size
)
215 int avail
, tpblks
, dblkno
;
217 dblkno
= fsbtodb(sblock
, blkno
);
218 tpblks
= size
>> tp_bshift
;
219 while ((avail
= MIN(tpblks
, ntrec
- trecno
)) > 0) {
220 slp
->req
[trecno
].dblk
= dblkno
;
221 slp
->req
[trecno
].count
= avail
;
223 spcl
.c_tapea
+= avail
;
226 dblkno
+= avail
<< (tp_bshift
- dev_bshift
);
238 msg("write error on %s\n", tape
);
239 quit("Cannot recover\n");
242 msg("write error %d blocks into volume %d\n", blocksthisvol
, tapeno
);
243 broadcast("DUMP WRITE ERROR!\n");
244 if (!query("Do you want to restart?"))
246 msg("Closing this volume. Prepare to restart with new media;\n");
247 msg("this dump volume will be rewritten.\n");
258 quit("Broken pipe\n");
263 * Update xferrate stats
276 ttaken
= tnow
- tstart_volume
;
277 blocks
= spcl
.c_tapea
- tapea_volume
;
278 msg("Volume %d completed at: %s", tapeno
,
285 msg("Volume %d took %d:%02d:%02d\n", tapeno
,
286 ttaken
/ 3600, (ttaken
% 3600) / 60, ttaken
% 60);
287 msg("Volume %d transfer rate: %ld KB/s\n", tapeno
,
289 xferrate
+= blocks
/ ttaken
;
297 * information message upon receipt of SIGINFO
298 * (derived from optr.c::timeest())
301 statussig(int notused
)
305 int save_errno
= errno
;
307 if (blockswritten
< 500)
312 (void) time((time_t *) &tnow
);
314 deltat
= tstart_writing
- tnow
+ (1.0 * (tnow
- tstart_writing
))
315 / blockswritten
* tapesize
;
316 (void)snprintf(msgbuf
, sizeof(msgbuf
),
317 "%3.2f%% done at %ld KB/s, finished in %d:%02d\n",
318 (blockswritten
* 100.0) / tapesize
,
319 (spcl
.c_tapea
- tapea_volume
) / (tnow
- tstart_volume
),
320 (int)(deltat
/ 3600), (int)((deltat
% 3600) / 60));
321 write(STDERR_FILENO
, msgbuf
, strlen(msgbuf
));
332 int siz
= (char *)nextblock
- (char *)slp
->req
;
334 slp
->req
[trecno
].count
= 0; /* Sentinel */
336 if (atomic_write( slp
->fd
, (char *)slp
->req
, siz
) != siz
)
337 quit("error writing command pipe: %s\n", strerror(errno
));
338 slp
->sent
= 1; /* we sent a request, read the response later */
340 lastfirstrec
= slp
->firstrec
;
342 if (++slp
>= &slaves
[SLAVES
])
345 /* Read results back from next slave */
347 if (atomic_read( slp
->fd
, (char *)&got
, sizeof got
)
349 perror(" DUMP: error reading command pipe in master");
354 /* Check for end of tape */
355 if (got
< writesize
) {
356 msg("End of tape detected\n");
359 * Drain the results, don't care what the values were.
360 * If we read them here then trewind won't...
362 for (i
= 0; i
< SLAVES
; i
++) {
363 if (slaves
[i
].sent
) {
364 if (atomic_read( slaves
[i
].fd
,
365 (char *)&got
, sizeof got
)
367 perror(" DUMP: error reading command pipe in master");
381 if (spcl
.c_type
!= TS_END
) {
382 for (i
= 0; i
< spcl
.c_count
; i
++)
383 if (spcl
.c_addr
[i
] != 0)
386 slp
->count
= lastspclrec
+ blks
+ 1 - spcl
.c_tapea
;
387 slp
->tapea
= spcl
.c_tapea
;
388 slp
->firstrec
= lastfirstrec
+ ntrec
;
390 nextblock
= slp
->tblock
;
393 blockswritten
+= ntrec
;
394 blocksthisvol
+= ntrec
;
395 if (!pipeout
&& !unlimited
&& (blocksperfile
?
396 (blocksthisvol
>= blocksperfile
) : (asize
> tsize
))) {
409 for (f
= 0; f
< SLAVES
; f
++) {
411 * Drain the results, but unlike EOT we DO (or should) care
412 * what the return values were, since if we detect EOT after
413 * we think we've written the last blocks to the tape anyway,
414 * we have to replay those blocks with rollforward.
416 * fixme: punt for now.
418 if (slaves
[f
].sent
) {
419 if (atomic_read( slaves
[f
].fd
, (char *)&got
, sizeof got
)
421 perror(" DUMP: error reading command pipe in master");
425 if (got
!= writesize
) {
426 msg("EOT detected in last 2 tape records!\n");
427 msg("Use a longer tape, decrease the size estimate\n");
428 quit("or use no size estimate at all.\n");
431 (void) close(slaves
[f
].fd
);
433 while (wait((int *)NULL
) >= 0) /* wait for any signals from slaves */
439 msg("Closing %s\n", tape
);
444 while (rmtopen(tape
, 0) < 0)
450 (void) close(tapefd
);
451 while ((f
= open(tape
, 0)) < 0)
461 if (nexttape
|| Mflag
)
464 msg("Change Volumes: Mount volume #%d\n", tapeno
+1);
465 broadcast("CHANGE DUMP VOLUMES!\7\7\n");
467 while (!query("Is the new volume mounted and ready to go?"))
468 if (query("Do you want to abort?")) {
477 register struct req
*p
, *q
, *prev
;
478 register struct slave
*tslp
;
479 int i
, size
, savedtapea
, got
;
480 union u_spcl
*ntb
, *otb
;
485 tslp
= &slaves
[SLAVES
];
486 ntb
= (union u_spcl
*)tslp
->tblock
[1];
489 * Each of the N slaves should have requests that need to
490 * be replayed on the next tape. Use the extra slave buffers
491 * (slaves[SLAVES]) to construct request lists to be sent to
492 * each slave in turn.
494 for (i
= 0; i
< SLAVES
; i
++) {
496 otb
= (union u_spcl
*)slp
->tblock
;
499 * For each request in the current slave, copy it to tslp.
503 for (p
= slp
->req
; p
->count
> 0; p
+= p
->count
) {
506 *ntb
++ = *otb
++; /* copy the datablock also */
511 quit("rollforward: protocol botch");
523 nextblock
= tslp
->tblock
;
524 savedtapea
= spcl
.c_tapea
;
525 spcl
.c_tapea
= slp
->tapea
;
527 spcl
.c_tapea
= savedtapea
;
528 lastspclrec
= savedtapea
- 1;
530 size
= (char *)ntb
- (char *)q
;
531 if (atomic_write( slp
->fd
, (char *)q
, size
) != size
) {
532 perror(" DUMP: error writing command pipe");
537 lastfirstrec
= slp
->firstrec
;
539 if (++slp
>= &slaves
[SLAVES
])
544 if (prev
->dblk
!= 0) {
546 * If the last one was a disk block, make the
547 * first of this one be the last bit of that disk
550 q
->dblk
= prev
->dblk
+
551 prev
->count
* (TP_BSIZE
/ DEV_BSIZE
);
552 ntb
= (union u_spcl
*)tslp
->tblock
;
555 * It wasn't a disk block. Copy the data to its
556 * new location in the buffer.
559 *((union u_spcl
*)tslp
->tblock
) = *ntb
;
560 ntb
= (union u_spcl
*)tslp
->tblock
[1];
564 nextblock
= slp
->tblock
;
567 *(union u_spcl
*)(*(nextblock
)++) = *(union u_spcl
*)tslp
->tblock
;
574 * Clear the first slaves' response. One hopes that it
575 * worked ok, otherwise the tape is much too short!
578 if (atomic_read( slp
->fd
, (char *)&got
, sizeof got
)
580 perror(" DUMP: error reading command pipe in master");
585 if (got
!= writesize
) {
586 quit("EOT detected at start of the tape!\n");
592 if (spcl
.c_type
!= TS_END
) {
593 for (i
= 0; i
< spcl
.c_count
; i
++)
594 if (spcl
.c_addr
[i
] != 0)
598 slp
->firstrec
= lastfirstrec
+ ntrec
;
599 slp
->count
= lastspclrec
+ blks
+ 1 - spcl
.c_tapea
;
602 blockswritten
+= ntrec
;
603 blocksthisvol
+= ntrec
;
608 * We implement taking and restoring checkpoints on the tape level.
609 * When each tape is opened, a new process is created by forking; this
610 * saves all of the necessary context in the parent. The child
611 * continues the dump; the parent waits around, saving the context.
612 * If the child returns X_REWRITE, then it had problems writing that tape;
613 * this causes the parent to fork again, duplicating the context, and
614 * everything continues as if nothing had happened.
617 startnewtape(int top
)
625 void (*interrupt_save
) __P((int signo
));
626 #else /* __linux__ */
628 void (*interrupt_save
)();
630 sig_t interrupt_save
;
632 #endif /* __linux__ */
634 interrupt_save
= signal(SIGINT
, SIG_IGN
);
635 parentpid
= getpid();
636 tapea_volume
= spcl
.c_tapea
;
638 (void)time4(&tstart_volume
);
640 (void)time((&tstart_volume
);
644 (void)signal(SIGINT
, interrupt_save
);
646 * All signals are inherited...
650 msg("Context save fork fails in parent %d\n", parentpid
);
656 * save the context by waiting
657 * until the child doing all of the work returns.
658 * don't catch the interrupt
660 signal(SIGINT
, SIG_IGN
);
662 msg("Tape: %d; parent process: %d child process %d\n",
663 tapeno
+1, parentpid
, childpid
);
665 while ((waitpid
= wait(&status
)) != childpid
)
666 if (waitpid
!= rshpid
)
667 msg("Parent %d waiting for child %d has another child %d return\n",
668 parentpid
, childpid
, waitpid
);
670 msg("Child %d returns LOB status %o\n",
671 childpid
, status
&0xFF);
673 status
= (status
>> 8) & 0xFF;
677 msg("Child %d finishes X_FINOK\n", childpid
);
680 msg("Child %d finishes X_ABORT\n", childpid
);
683 msg("Child %d finishes X_REWRITE\n", childpid
);
686 msg("Child %d finishes unknown %d\n",
697 goto restore_check_point
;
699 msg("Bad return code from dump: %d\n", status
);
703 } else { /* we are the child; just continue */
705 sleep(4); /* allow time for parent's message to get out */
706 msg("Child on Tape %d has parent %d, my pid = %d\n",
707 tapeno
+1, parentpid
, getpid());
710 * If we have a name like "/dev/rmt0,/dev/rmt1",
711 * use the name before the comma first, and save
712 * the remaining names for subsequent volumes.
714 tapeno
++; /* current tape sequence */
716 snprintf(tape
, NAME_MAX
, "%s%03d", tapeprefix
, tapeno
);
717 tape
[NAME_MAX
- 1] = '\0';
718 msg("Dumping volume %d on %s\n", tapeno
, tape
);
720 else if (nexttape
|| strchr(tapeprefix
, ',')) {
721 if (nexttape
&& *nexttape
)
722 tapeprefix
= nexttape
;
723 if ((p
= strchr(tapeprefix
, ',')) != NULL
) {
728 strncpy(tape
, tapeprefix
, NAME_MAX
);
729 tape
[NAME_MAX
- 1] = '\0';
730 msg("Dumping volume %d on %s\n", tapeno
, tape
);
733 while ((tapefd
= (host
? rmtopen(tape
, 2) :
734 pipeout
? 1 : open(tape
, O_WRONLY
|O_CREAT
, 0666))) < 0)
736 while ((tapefd
= (pipeout
? 1 :
737 open(tape
, O_WRONLY
|O_CREAT
, 0666))) < 0)
740 msg("Cannot open output \"%s\".\n", tape
);
741 if (!query("Do you want to retry the open?"))
745 enslave(); /* Share open tape file descriptor with slaves */
750 newtape
++; /* new tape signal */
751 spcl
.c_count
= slp
->count
;
753 * measure firstrec in TP_BSIZE units since restore doesn't
754 * know the correct ntrec value...
756 spcl
.c_firstrec
= slp
->firstrec
;
758 spcl
.c_type
= TS_TAPE
;
759 spcl
.c_flags
|= DR_NEWHEADER
;
760 writeheader((ino_t
)slp
->inode
);
761 spcl
.c_flags
&=~ DR_NEWHEADER
;
762 msg("Volume %d started at: %s", tapeno
,
764 ctime4(&tstart_volume
));
766 ctime(&tstart_volume
));
769 msg("Volume %d begins with blocks from inode %d\n",
778 if (master
!= 0 && master
!= getpid())
779 /* Signals master to call dumpabort */
780 (void) kill(master
, SIGTERM
);
783 msg("The ENTIRE dump is aborted.\n");
796 msg("pid = %d exits with status %d\n", getpid(), status
);
802 * proceed - handler for SIGUSR2, used to synchronize IO between the slaves.
809 siglongjmp(jmpbuf
, 1);
817 #ifdef LINUX_FORK_BUG
825 signal(SIGTERM
, dumpabort
); /* Slave sends SIGTERM on dumpabort() */
826 signal(SIGPIPE
, sigpipe
);
827 signal(SIGUSR1
, tperror
); /* Slave sends SIGUSR1 on tape errors */
828 signal(SIGUSR2
, proceed
); /* Slave sends SIGUSR2 to next slave */
830 for (i
= 0; i
< SLAVES
; i
++) {
831 if (i
== slp
- &slaves
[0]) {
837 if (socketpair(AF_UNIX
, SOCK_STREAM
, 0, cmd
) < 0 ||
838 (slaves
[i
].pid
= fork()) < 0)
839 quit("too many slaves, %d (recompile smaller): %s\n",
842 slaves
[i
].fd
= cmd
[1];
844 if (slaves
[i
].pid
== 0) { /* Slave starts up here */
845 for (j
= 0; j
<= i
; j
++)
846 (void) close(slaves
[j
].fd
);
847 signal(SIGINT
, SIG_IGN
); /* Master handles this */
849 signal(SIGINFO
, SIG_IGN
);
852 #ifdef LINUX_FORK_BUG
853 if (atomic_write( cmd
[0], (char *) &i
, sizeof i
)
855 quit("master/slave protocol botched 3\n");
862 #ifdef LINUX_FORK_BUG
864 * Wait for all slaves to _actually_ start to circumvent a bug in
865 * Linux kernels >= 2.1.3 where a signal sent to a child that hasn't
866 * returned from fork() causes a SEGV in the child process
868 for (i
= 0; i
< SLAVES
; i
++)
869 if (atomic_read( slaves
[i
].fd
, (char *) &j
, sizeof j
) != sizeof j
)
870 quit("master/slave protocol botched 4\n");
873 for (i
= 0; i
< SLAVES
; i
++)
874 (void) atomic_write( slaves
[i
].fd
,
875 (char *) &slaves
[(i
+ 1) % SLAVES
].pid
,
876 sizeof slaves
[0].pid
);
886 for (i
= 0; i
< SLAVES
; i
++)
887 if (slaves
[i
].pid
> 0) {
888 (void) kill(slaves
[i
].pid
, SIGKILL
);
894 * Synchronization - each process has a lockfile, and shares file
895 * descriptors to the following process's lockfile. When our write
896 * completes, we release our lock on the following process's lock-
897 * file, allowing the following process to lock it and proceed. We
898 * get the lock back for the next cycle by swapping descriptors.
901 doslave(int cmd
, int slave_number
)
904 int nextslave
, size
, eot_count
;
905 volatile int wrote
= 0;
912 * Need our own seek pointer.
914 (void) close(diskfd
);
915 if ((diskfd
= open(disk
, O_RDONLY
)) < 0)
916 quit("slave couldn't reopen disk: %s\n", strerror(errno
));
919 retval
= dump_fs_open(disk
, &fs
);
921 quit("slave couldn't reopen disk: %s\n", error_message(retval
));
922 #endif /* __linux__ */
925 * Need the pid of the next slave in the loop...
927 if ((nread
= atomic_read( cmd
, (char *)&nextslave
, sizeof nextslave
))
928 != sizeof nextslave
) {
929 quit("master/slave protocol botched - didn't get pid of next slave.\n");
933 * Get list of blocks to dump, read the blocks into tape buffer
935 while ((nread
= atomic_read( cmd
, (char *)slp
->req
, reqsiz
)) == reqsiz
) {
936 register struct req
*p
= slp
->req
;
938 for (trecno
= 0; trecno
< ntrec
;
939 trecno
+= p
->count
, p
+= p
->count
) {
941 bread(p
->dblk
, slp
->tblock
[trecno
],
942 p
->count
* TP_BSIZE
);
944 if (p
->count
!= 1 || atomic_read( cmd
,
945 (char *)slp
->tblock
[trecno
],
946 TP_BSIZE
) != TP_BSIZE
)
947 quit("master/slave protocol botched.\n");
950 if (setjmp(jmpbuf
) == 0) {
958 /* Try to write the data... */
963 while (eot_count
< 10 && size
< writesize
) {
966 wrote
= rmtwrite(slp
->tblock
[0]+size
,
970 wrote
= write(tapefd
, slp
->tblock
[0]+size
,
973 printf("slave %d wrote %d\n", slave_number
, wrote
);
983 if (size
!= writesize
)
984 printf("slave %d only wrote %d out of %d bytes and gave up.\n",
985 slave_number
, size
, writesize
);
989 * Handle ENOSPC as an EOT condition.
991 if (wrote
< 0 && errno
== ENOSPC
) {
1000 (void) kill(master
, SIGUSR1
);
1001 sigemptyset(&sigset
);
1003 sigsuspend(&sigset
);
1006 * pass size of write back to master
1007 * (for EOT handling)
1009 (void) atomic_write( cmd
, (char *)&size
, sizeof size
);
1013 * If partial write, don't want next slave to go.
1014 * Also jolts him awake.
1016 (void) kill(nextslave
, SIGUSR2
);
1019 quit("error reading command pipe: %s\n", strerror(errno
));
1023 * Since a read from a pipe may not return all we asked for,
1024 * or a write may not write all we ask if we get a signal,
1025 * loop until the count is satisfied (or error).
1028 atomic_read(int fd
, void *buf
, size_t count
)
1030 int got
, need
= count
;
1033 while ((got
= read(fd
, buf
, need
)) > 0 && (need
-= got
) > 0)
1035 } while (got
== -1 && errno
== EINTR
);
1036 return (got
< 0 ? got
: count
- need
);
1040 * Since a read from a pipe may not return all we asked for,
1041 * or a write may not write all we ask if we get a signal,
1042 * loop until the count is satisfied (or error).
1045 atomic_write(int fd
, const void *buf
, size_t count
)
1047 int got
, need
= count
;
1050 while ((got
= write(fd
, buf
, need
)) > 0 && (need
-= got
) > 0)
1052 } while (got
== -1 && errno
== EINTR
);
1053 return (got
< 0 ? got
: count
- need
);