]>
git.wh0rd.org - dump.git/blob - dump/tape.c
b48665ef0e274e4732598a4bc9df8160b298ab1c
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
10 * Copyright (c) 1980, 1991, 1993
11 * The Regents of the University of California. All rights reserved.
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. All advertising materials mentioning features or use of this software
22 * must display the following acknowledgement:
23 * This product includes software developed by the University of
24 * California, Berkeley and its contributors.
25 * 4. Neither the name of the University nor the names of its contributors
26 * may be used to endorse or promote products derived from this software
27 * without specific prior written permission.
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44 static char sccsid
[] = "@(#)tape.c 8.4 (Berkeley) 5/1/95";
46 static const char rcsid
[] =
47 "$Id: tape.c,v 1.3 1999/10/11 12:59:19 stelian Exp $";
51 #include <sys/types.h>
52 #include <linux/types.h>
54 #include <sys/param.h>
55 #include <sys/socket.h>
59 #include <linux/ext2_fs.h>
60 #include <bsdcompat.h>
63 #include <sys/vnode.h>
66 #include <ufs/inode.h>
68 #include <ufs/ufs/dinode.h>
69 #include <ufs/ffs/fs.h>
71 #endif /* __linux__ */
73 #include <protocols/dumprestore.h>
89 #include <ext2fs/ext2fs.h>
93 int writesize
; /* size of malloc()ed buffer for tape */
94 long lastspclrec
= -1; /* tape block number of last written header */
95 int trecno
= 0; /* next record to write in current block */
96 extern long blocksperfile
; /* number of blocks per output file */
97 long blocksthisvol
; /* number of blocks on current output file */
98 extern int ntrec
; /* blocking factor on tape */
103 static ssize_t atomic_read
__P((int, void *, size_t));
104 static ssize_t atomic_write
__P((int, const void *, size_t));
105 static void doslave
__P((int, int));
106 static void enslave
__P((void));
107 static void flushtape
__P((void));
108 static void killall
__P((void));
109 static void rollforward
__P((void));
112 * Concurrent dump mods (Caltech) - disk block reading and tape writing
113 * are exported to several slave processes. While one slave writes the
114 * tape, the others read disk blocks; they pass control of the tape in
115 * a ring via signals. The parent process traverses the filesystem and
116 * sends writeheader()'s and lists of daddr's to the slaves via pipes.
117 * The following structure defines the instruction packets sent to slaves.
125 #define SLAVES 3 /* 1 slave writing, 1 reading, 1 for slack */
127 int tapea
; /* header number at start of this chunk */
128 int count
; /* count to next header (used for TS_TAPE */
130 int inode
; /* inode that we are currently dealing with */
131 int fd
; /* FD for this slave */
132 int pid
; /* PID for this slave */
133 int sent
; /* 1 == we've sent this slave requests */
134 int firstrec
; /* record number of this block */
135 char (*tblock
)[TP_BSIZE
]; /* buffer for data blocks */
136 struct req
*req
; /* buffer for requests */
140 char (*nextblock
)[TP_BSIZE
];
142 static time_t tstart_volume
; /* time of volume start */
143 static int tapea_volume
; /* value of spcl.c_tapea at volume start */
145 int master
; /* pid of master, for sending error signals */
146 int tenths
; /* length of tape used per block written */
147 static int caught
; /* have we caught the signal to proceed? */
148 static int ready
; /* have we reached the lock point without having */
149 /* received the SIGUSR2 signal from the prev slave? */
150 static sigjmp_buf jmpbuf
; /* where to jump to if we are ready when the */
151 /* SIGUSR2 arrives from the previous slave */
156 int pgoff
= getpagesize() - 1;
160 writesize
= ntrec
* TP_BSIZE
;
161 reqsiz
= (ntrec
+ 1) * sizeof(struct req
);
163 * CDC 92181's and 92185's make 0.8" gaps in 1600-bpi start/stop mode
164 * (see DEC TU80 User's Guide). The shorter gaps of 6250-bpi require
165 * repositioning after stopping, i.e, streaming mode, where the gap is
166 * variable, 0.30" to 0.45". The gap is maximal when the tape stops.
168 if (blocksperfile
== 0 && !unlimited
)
169 tenths
= writesize
/ density
+
170 (cartridge
? 16 : density
== 625 ? 5 : 8);
172 * Allocate tape buffer contiguous with the array of instruction
173 * packets, so flushtape() can write them together with one write().
174 * Align tape buffer on page boundary to speed up tape write().
176 for (i
= 0; i
<= SLAVES
; i
++) {
178 malloc((unsigned)(reqsiz
+ writesize
+ pgoff
+ TP_BSIZE
));
181 slaves
[i
].tblock
= (char (*)[TP_BSIZE
])
183 (((long)&buf
[reqsiz
] + pgoff
) &~ pgoff
);
185 (((long)&buf
[ntrec
+ 1] + pgoff
) &~ pgoff
);
187 slaves
[i
].req
= (struct req
*)slaves
[i
].tblock
- ntrec
- 1;
193 nextblock
= slp
->tblock
;
198 writerec(const void *dp
, int isspcl
)
201 slp
->req
[trecno
].dblk
= (daddr_t
)0;
202 slp
->req
[trecno
].count
= 1;
203 /* XXX post increment triggers an egcs-1.1.2-12 bug on alpha/sparc */
204 *(union u_spcl
*)(*(nextblock
)) = *(union u_spcl
*)dp
;
207 lastspclrec
= spcl
.c_tapea
;
215 dumpblock(daddr_t blkno
, int size
)
217 int avail
, tpblks
, dblkno
;
219 dblkno
= fsbtodb(sblock
, blkno
);
220 tpblks
= size
>> tp_bshift
;
221 while ((avail
= MIN(tpblks
, ntrec
- trecno
)) > 0) {
222 slp
->req
[trecno
].dblk
= dblkno
;
223 slp
->req
[trecno
].count
= avail
;
225 spcl
.c_tapea
+= avail
;
228 dblkno
+= avail
<< (tp_bshift
- dev_bshift
);
240 msg("write error on %s\n", tape
);
241 quit("Cannot recover\n");
244 msg("write error %d blocks into volume %d\n", blocksthisvol
, tapeno
);
245 broadcast("DUMP WRITE ERROR!\n");
246 if (!query("Do you want to restart?"))
248 msg("Closing this volume. Prepare to restart with new media;\n");
249 msg("this dump volume will be rewritten.\n");
260 quit("Broken pipe\n");
265 * Update xferrate stats
274 ttaken
= tnow
- tstart_volume
;
275 blocks
= spcl
.c_tapea
- tapea_volume
;
276 msg("Volume %d completed at: %s", tapeno
, ctime(&tnow
));
278 msg("Volume %d took %d:%02d:%02d\n", tapeno
,
279 ttaken
/ 3600, (ttaken
% 3600) / 60, ttaken
% 60);
280 msg("Volume %d transfer rate: %ld KB/s\n", tapeno
,
282 xferrate
+= blocks
/ ttaken
;
290 * information message upon receipt of SIGINFO
291 * (derived from optr.c::timeest())
294 statussig(int notused
)
298 int save_errno
= errno
;
300 if (blockswritten
< 500)
302 (void) time((time_t *) &tnow
);
303 deltat
= tstart_writing
- tnow
+ (1.0 * (tnow
- tstart_writing
))
304 / blockswritten
* tapesize
;
305 (void)snprintf(msgbuf
, sizeof(msgbuf
),
306 "%3.2f%% done at %ld KB/s, finished in %d:%02d\n",
307 (blockswritten
* 100.0) / tapesize
,
308 (spcl
.c_tapea
- tapea_volume
) / (tnow
- tstart_volume
),
309 (int)(deltat
/ 3600), (int)((deltat
% 3600) / 60));
310 write(STDERR_FILENO
, msgbuf
, strlen(msgbuf
));
321 int siz
= (char *)nextblock
- (char *)slp
->req
;
323 slp
->req
[trecno
].count
= 0; /* Sentinel */
325 if (atomic_write( slp
->fd
, (char *)slp
->req
, siz
) != siz
)
326 quit("error writing command pipe: %s\n", strerror(errno
));
327 slp
->sent
= 1; /* we sent a request, read the response later */
329 lastfirstrec
= slp
->firstrec
;
331 if (++slp
>= &slaves
[SLAVES
])
334 /* Read results back from next slave */
336 if (atomic_read( slp
->fd
, (char *)&got
, sizeof got
)
338 perror(" DUMP: error reading command pipe in master");
343 /* Check for end of tape */
344 if (got
< writesize
) {
345 msg("End of tape detected\n");
348 * Drain the results, don't care what the values were.
349 * If we read them here then trewind won't...
351 for (i
= 0; i
< SLAVES
; i
++) {
352 if (slaves
[i
].sent
) {
353 if (atomic_read( slaves
[i
].fd
,
354 (char *)&got
, sizeof got
)
356 perror(" DUMP: error reading command pipe in master");
370 if (spcl
.c_type
!= TS_END
) {
371 for (i
= 0; i
< spcl
.c_count
; i
++)
372 if (spcl
.c_addr
[i
] != 0)
375 slp
->count
= lastspclrec
+ blks
+ 1 - spcl
.c_tapea
;
376 slp
->tapea
= spcl
.c_tapea
;
377 slp
->firstrec
= lastfirstrec
+ ntrec
;
379 nextblock
= slp
->tblock
;
382 blockswritten
+= ntrec
;
383 blocksthisvol
+= ntrec
;
384 if (!pipeout
&& !unlimited
&& (blocksperfile
?
385 (blocksthisvol
>= blocksperfile
) : (asize
> tsize
))) {
398 for (f
= 0; f
< SLAVES
; f
++) {
400 * Drain the results, but unlike EOT we DO (or should) care
401 * what the return values were, since if we detect EOT after
402 * we think we've written the last blocks to the tape anyway,
403 * we have to replay those blocks with rollforward.
405 * fixme: punt for now.
407 if (slaves
[f
].sent
) {
408 if (atomic_read( slaves
[f
].fd
, (char *)&got
, sizeof got
)
410 perror(" DUMP: error reading command pipe in master");
414 if (got
!= writesize
) {
415 msg("EOT detected in last 2 tape records!\n");
416 msg("Use a longer tape, decrease the size estimate\n");
417 quit("or use no size estimate at all.\n");
420 (void) close(slaves
[f
].fd
);
422 while (wait((int *)NULL
) >= 0) /* wait for any signals from slaves */
428 msg("Closing %s\n", tape
);
433 while (rmtopen(tape
, 0) < 0)
439 (void) close(tapefd
);
440 while ((f
= open(tape
, 0)) < 0)
448 time_t tstart_changevol
, tend_changevol
;
455 (void)time4(&(tstart_changevol
));
457 (void)time((time_t *)&(tstart_changevol
));
460 msg("Change Volumes: Mount volume #%d\n", tapeno
+1);
461 broadcast("CHANGE DUMP VOLUMES!\7\7\n");
463 while (!query("Is the new volume mounted and ready to go?"))
464 if (query("Do you want to abort?")) {
469 (void)time4(&(tend_changevol
));
471 (void)time((time_t *)&(tend_changevol
));
473 if ((tstart_changevol
!= (time_t)-1) && (tend_changevol
!= (time_t)-1))
474 tstart_writing
+= (tend_changevol
- tstart_changevol
);
480 register struct req
*p
, *q
, *prev
;
481 register struct slave
*tslp
;
482 int i
, size
, savedtapea
, got
;
483 union u_spcl
*ntb
, *otb
;
488 tslp
= &slaves
[SLAVES
];
489 ntb
= (union u_spcl
*)tslp
->tblock
[1];
492 * Each of the N slaves should have requests that need to
493 * be replayed on the next tape. Use the extra slave buffers
494 * (slaves[SLAVES]) to construct request lists to be sent to
495 * each slave in turn.
497 for (i
= 0; i
< SLAVES
; i
++) {
499 otb
= (union u_spcl
*)slp
->tblock
;
502 * For each request in the current slave, copy it to tslp.
506 for (p
= slp
->req
; p
->count
> 0; p
+= p
->count
) {
509 *ntb
++ = *otb
++; /* copy the datablock also */
514 quit("rollforward: protocol botch");
526 nextblock
= tslp
->tblock
;
527 savedtapea
= spcl
.c_tapea
;
528 spcl
.c_tapea
= slp
->tapea
;
530 spcl
.c_tapea
= savedtapea
;
531 lastspclrec
= savedtapea
- 1;
533 size
= (char *)ntb
- (char *)q
;
534 if (atomic_write( slp
->fd
, (char *)q
, size
) != size
) {
535 perror(" DUMP: error writing command pipe");
540 lastfirstrec
= slp
->firstrec
;
542 if (++slp
>= &slaves
[SLAVES
])
547 if (prev
->dblk
!= 0) {
549 * If the last one was a disk block, make the
550 * first of this one be the last bit of that disk
553 q
->dblk
= prev
->dblk
+
554 prev
->count
* (TP_BSIZE
/ DEV_BSIZE
);
555 ntb
= (union u_spcl
*)tslp
->tblock
;
558 * It wasn't a disk block. Copy the data to its
559 * new location in the buffer.
562 *((union u_spcl
*)tslp
->tblock
) = *ntb
;
563 ntb
= (union u_spcl
*)tslp
->tblock
[1];
567 nextblock
= slp
->tblock
;
570 *(union u_spcl
*)(*(nextblock
)++) = *(union u_spcl
*)tslp
->tblock
;
577 * Clear the first slaves' response. One hopes that it
578 * worked ok, otherwise the tape is much too short!
581 if (atomic_read( slp
->fd
, (char *)&got
, sizeof got
)
583 perror(" DUMP: error reading command pipe in master");
588 if (got
!= writesize
) {
589 quit("EOT detected at start of the tape!\n");
595 if (spcl
.c_type
!= TS_END
) {
596 for (i
= 0; i
< spcl
.c_count
; i
++)
597 if (spcl
.c_addr
[i
] != 0)
601 slp
->firstrec
= lastfirstrec
+ ntrec
;
602 slp
->count
= lastspclrec
+ blks
+ 1 - spcl
.c_tapea
;
605 blockswritten
+= ntrec
;
606 blocksthisvol
+= ntrec
;
611 * We implement taking and restoring checkpoints on the tape level.
612 * When each tape is opened, a new process is created by forking; this
613 * saves all of the necessary context in the parent. The child
614 * continues the dump; the parent waits around, saving the context.
615 * If the child returns X_REWRITE, then it had problems writing that tape;
616 * this causes the parent to fork again, duplicating the context, and
617 * everything continues as if nothing had happened.
620 startnewtape(int top
)
628 void (*interrupt_save
) __P((int signo
));
629 #else /* __linux__ */
631 void (*interrupt_save
)();
633 sig_t interrupt_save
;
635 #endif /* __linux__ */
637 interrupt_save
= signal(SIGINT
, SIG_IGN
);
638 parentpid
= getpid();
639 tapea_volume
= spcl
.c_tapea
;
640 (void)time(&tstart_volume
);
643 (void)signal(SIGINT
, interrupt_save
);
645 * All signals are inherited...
649 msg("Context save fork fails in parent %d\n", parentpid
);
655 * save the context by waiting
656 * until the child doing all of the work returns.
657 * don't catch the interrupt
659 signal(SIGINT
, SIG_IGN
);
661 msg("Tape: %d; parent process: %d child process %d\n",
662 tapeno
+1, parentpid
, childpid
);
664 while ((waitpid
= wait(&status
)) != childpid
)
665 msg("Parent %d waiting for child %d has another child %d return\n",
666 parentpid
, childpid
, waitpid
);
668 msg("Child %d returns LOB status %o\n",
669 childpid
, status
&0xFF);
671 status
= (status
>> 8) & 0xFF;
675 msg("Child %d finishes X_FINOK\n", childpid
);
678 msg("Child %d finishes X_ABORT\n", childpid
);
681 msg("Child %d finishes X_REWRITE\n", childpid
);
684 msg("Child %d finishes unknown %d\n",
695 goto restore_check_point
;
697 msg("Bad return code from dump: %d\n", status
);
701 } else { /* we are the child; just continue */
703 sleep(4); /* allow time for parent's message to get out */
704 msg("Child on Tape %d has parent %d, my pid = %d\n",
705 tapeno
+1, parentpid
, getpid());
708 * If we have a name like "/dev/rmt0,/dev/rmt1",
709 * use the name before the comma first, and save
710 * the remaining names for subsequent volumes.
712 tapeno
++; /* current tape sequence */
713 if (nexttape
|| strchr(tape
, ',')) {
714 if (nexttape
&& *nexttape
)
716 if ((p
= strchr(tape
, ',')) != NULL
) {
721 msg("Dumping volume %d on %s\n", tapeno
, tape
);
724 while ((tapefd
= (host
? rmtopen(tape
, 2) :
725 pipeout
? 1 : open(tape
, O_WRONLY
|O_CREAT
, 0666))) < 0)
727 while ((tapefd
= (pipeout
? 1 :
728 open(tape
, O_WRONLY
|O_CREAT
, 0666))) < 0)
731 msg("Cannot open output \"%s\".\n", tape
);
732 if (!query("Do you want to retry the open?"))
736 enslave(); /* Share open tape file descriptor with slaves */
741 newtape
++; /* new tape signal */
742 spcl
.c_count
= slp
->count
;
744 * measure firstrec in TP_BSIZE units since restore doesn't
745 * know the correct ntrec value...
747 spcl
.c_firstrec
= slp
->firstrec
;
749 spcl
.c_type
= TS_TAPE
;
750 spcl
.c_flags
|= DR_NEWHEADER
;
751 writeheader((ino_t
)slp
->inode
);
752 spcl
.c_flags
&=~ DR_NEWHEADER
;
753 msg("Volume %d started at: %s", tapeno
, ctime(&tstart_volume
));
755 msg("Volume %d begins with blocks from inode %d\n",
764 if (master
!= 0 && master
!= getpid())
765 /* Signals master to call dumpabort */
766 (void) kill(master
, SIGTERM
);
769 msg("The ENTIRE dump is aborted.\n");
782 msg("pid = %d exits with status %d\n", getpid(), status
);
788 * proceed - handler for SIGUSR2, used to synchronize IO between the slaves.
795 siglongjmp(jmpbuf
, 1);
803 #ifdef LINUX_FORK_BUG
811 signal(SIGTERM
, dumpabort
); /* Slave sends SIGTERM on dumpabort() */
812 signal(SIGPIPE
, sigpipe
);
813 signal(SIGUSR1
, tperror
); /* Slave sends SIGUSR1 on tape errors */
814 signal(SIGUSR2
, proceed
); /* Slave sends SIGUSR2 to next slave */
816 for (i
= 0; i
< SLAVES
; i
++) {
817 if (i
== slp
- &slaves
[0]) {
823 if (socketpair(AF_UNIX
, SOCK_STREAM
, 0, cmd
) < 0 ||
824 (slaves
[i
].pid
= fork()) < 0)
825 quit("too many slaves, %d (recompile smaller): %s\n",
828 slaves
[i
].fd
= cmd
[1];
830 if (slaves
[i
].pid
== 0) { /* Slave starts up here */
831 for (j
= 0; j
<= i
; j
++)
832 (void) close(slaves
[j
].fd
);
833 signal(SIGINT
, SIG_IGN
); /* Master handles this */
835 signal(SIGINFO
, SIG_IGN
);
838 #ifdef LINUX_FORK_BUG
839 if (atomic_write( cmd
[0], (char *) &i
, sizeof i
)
841 quit("master/slave protocol botched 3\n");
848 #ifdef LINUX_FORK_BUG
850 * Wait for all slaves to _actually_ start to circumvent a bug in
851 * Linux kernels >= 2.1.3 where a signal sent to a child that hasn't
852 * returned from fork() causes a SEGV in the child process
854 for (i
= 0; i
< SLAVES
; i
++)
855 if (atomic_read( slaves
[i
].fd
, (char *) &j
, sizeof j
) != sizeof j
)
856 quit("master/slave protocol botched 4\n");
859 for (i
= 0; i
< SLAVES
; i
++)
860 (void) atomic_write( slaves
[i
].fd
,
861 (char *) &slaves
[(i
+ 1) % SLAVES
].pid
,
862 sizeof slaves
[0].pid
);
872 for (i
= 0; i
< SLAVES
; i
++)
873 if (slaves
[i
].pid
> 0) {
874 (void) kill(slaves
[i
].pid
, SIGKILL
);
880 * Synchronization - each process has a lockfile, and shares file
881 * descriptors to the following process's lockfile. When our write
882 * completes, we release our lock on the following process's lock-
883 * file, allowing the following process to lock it and proceed. We
884 * get the lock back for the next cycle by swapping descriptors.
887 doslave(int cmd
, int slave_number
)
890 int nextslave
, size
, eot_count
;
891 volatile int wrote
= 0;
898 * Need our own seek pointer.
900 (void) close(diskfd
);
901 if ((diskfd
= open(disk
, O_RDONLY
)) < 0)
902 quit("slave couldn't reopen disk: %s\n", strerror(errno
));
905 retval
= ext2fs_open(disk
, 0, 0, 0, unix_io_manager
, &fs
);
907 quit("slave couldn't reopen disk: %s\n", strerror(errno
));
908 #endif /* __linux__ */
911 * Need the pid of the next slave in the loop...
913 if ((nread
= atomic_read( cmd
, (char *)&nextslave
, sizeof nextslave
))
914 != sizeof nextslave
) {
915 quit("master/slave protocol botched - didn't get pid of next slave.\n");
919 * Get list of blocks to dump, read the blocks into tape buffer
921 while ((nread
= atomic_read( cmd
, (char *)slp
->req
, reqsiz
)) == reqsiz
) {
922 register struct req
*p
= slp
->req
;
924 for (trecno
= 0; trecno
< ntrec
;
925 trecno
+= p
->count
, p
+= p
->count
) {
927 bread(p
->dblk
, slp
->tblock
[trecno
],
928 p
->count
* TP_BSIZE
);
930 if (p
->count
!= 1 || atomic_read( cmd
,
931 (char *)slp
->tblock
[trecno
],
932 TP_BSIZE
) != TP_BSIZE
)
933 quit("master/slave protocol botched.\n");
936 if (setjmp(jmpbuf
) == 0) {
944 /* Try to write the data... */
949 while (eot_count
< 10 && size
< writesize
) {
952 wrote
= rmtwrite(slp
->tblock
[0]+size
,
956 wrote
= write(tapefd
, slp
->tblock
[0]+size
,
959 printf("slave %d wrote %d\n", slave_number
, wrote
);
969 if (size
!= writesize
)
970 printf("slave %d only wrote %d out of %d bytes and gave up.\n",
971 slave_number
, size
, writesize
);
975 * Handle ENOSPC as an EOT condition.
977 if (wrote
< 0 && errno
== ENOSPC
) {
986 (void) kill(master
, SIGUSR1
);
987 sigemptyset(&sigset
);
992 * pass size of write back to master
995 (void) atomic_write( cmd
, (char *)&size
, sizeof size
);
999 * If partial write, don't want next slave to go.
1000 * Also jolts him awake.
1002 (void) kill(nextslave
, SIGUSR2
);
1005 quit("error reading command pipe: %s\n", strerror(errno
));
1009 * Since a read from a pipe may not return all we asked for,
1010 * or a write may not write all we ask if we get a signal,
1011 * loop until the count is satisfied (or error).
1014 atomic_read(int fd
, void *buf
, size_t count
)
1016 int got
, need
= count
;
1018 while ((got
= read(fd
, buf
, need
)) > 0 && (need
-= got
) > 0)
1020 return (got
< 0 ? got
: count
- need
);
1024 * Since a read from a pipe may not return all we asked for,
1025 * or a write may not write all we ask if we get a signal,
1026 * loop until the count is satisfied (or error).
1029 atomic_write(int fd
, const void *buf
, size_t count
)
1031 int got
, need
= count
;
1033 while ((got
= write(fd
, buf
, need
)) > 0 && (need
-= got
) > 0)
1035 return (got
< 0 ? got
: count
- need
);