]>
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
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 1.7 1999/11/02 09:35:56 tiniou 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>
89 int writesize
; /* size of malloc()ed buffer for tape */
90 long lastspclrec
= -1; /* tape block number of last written header */
91 int trecno
= 0; /* next record to write in current block */
92 extern long blocksperfile
; /* number of blocks per output file */
93 long blocksthisvol
; /* number of blocks on current output file */
94 extern int ntrec
; /* blocking factor on tape */
100 static ssize_t atomic_read
__P((int, void *, size_t));
101 static ssize_t atomic_write
__P((int, const void *, size_t));
102 static void doslave
__P((int, int));
103 static void enslave
__P((void));
104 static void flushtape
__P((void));
105 static void killall
__P((void));
106 static void rollforward
__P((void));
109 * Concurrent dump mods (Caltech) - disk block reading and tape writing
110 * are exported to several slave processes. While one slave writes the
111 * tape, the others read disk blocks; they pass control of the tape in
112 * a ring via signals. The parent process traverses the filesystem and
113 * sends writeheader()'s and lists of daddr's to the slaves via pipes.
114 * The following structure defines the instruction packets sent to slaves.
122 #define SLAVES 3 /* 1 slave writing, 1 reading, 1 for slack */
124 int tapea
; /* header number at start of this chunk */
125 int count
; /* count to next header (used for TS_TAPE */
127 int inode
; /* inode that we are currently dealing with */
128 int fd
; /* FD for this slave */
129 int pid
; /* PID for this slave */
130 int sent
; /* 1 == we've sent this slave requests */
131 int firstrec
; /* record number of this block */
132 char (*tblock
)[TP_BSIZE
]; /* buffer for data blocks */
133 struct req
*req
; /* buffer for requests */
137 char (*nextblock
)[TP_BSIZE
];
139 static time_t tstart_volume
; /* time of volume start */
140 static int tapea_volume
; /* value of spcl.c_tapea at volume start */
142 int master
; /* pid of master, for sending error signals */
143 int tenths
; /* length of tape used per block written */
144 static int caught
; /* have we caught the signal to proceed? */
145 static int ready
; /* have we reached the lock point without having */
146 /* received the SIGUSR2 signal from the prev slave? */
147 static sigjmp_buf jmpbuf
; /* where to jump to if we are ready when the */
148 /* SIGUSR2 arrives from the previous slave */
153 int pgoff
= getpagesize() - 1;
157 writesize
= ntrec
* TP_BSIZE
;
158 reqsiz
= (ntrec
+ 1) * sizeof(struct req
);
160 * CDC 92181's and 92185's make 0.8" gaps in 1600-bpi start/stop mode
161 * (see DEC TU80 User's Guide). The shorter gaps of 6250-bpi require
162 * repositioning after stopping, i.e, streaming mode, where the gap is
163 * variable, 0.30" to 0.45". The gap is maximal when the tape stops.
165 if (blocksperfile
== 0 && !unlimited
)
166 tenths
= writesize
/ density
+
167 (cartridge
? 16 : density
== 625 ? 5 : 8);
169 * Allocate tape buffer contiguous with the array of instruction
170 * packets, so flushtape() can write them together with one write().
171 * Align tape buffer on page boundary to speed up tape write().
173 for (i
= 0; i
<= SLAVES
; i
++) {
175 malloc((unsigned)(reqsiz
+ writesize
+ pgoff
+ TP_BSIZE
));
178 slaves
[i
].tblock
= (char (*)[TP_BSIZE
])
180 (((long)&buf
[reqsiz
] + pgoff
) &~ pgoff
);
182 (((long)&buf
[ntrec
+ 1] + pgoff
) &~ pgoff
);
184 slaves
[i
].req
= (struct req
*)slaves
[i
].tblock
- ntrec
- 1;
190 nextblock
= slp
->tblock
;
195 writerec(const void *dp
, int isspcl
)
198 slp
->req
[trecno
].dblk
= (daddr_t
)0;
199 slp
->req
[trecno
].count
= 1;
200 /* XXX post increment triggers an egcs-1.1.2-12 bug on alpha/sparc */
201 *(union u_spcl
*)(*(nextblock
)) = *(union u_spcl
*)dp
;
204 lastspclrec
= spcl
.c_tapea
;
212 dumpblock(daddr_t blkno
, int size
)
214 int avail
, tpblks
, dblkno
;
216 dblkno
= fsbtodb(sblock
, blkno
);
217 tpblks
= size
>> tp_bshift
;
218 while ((avail
= MIN(tpblks
, ntrec
- trecno
)) > 0) {
219 slp
->req
[trecno
].dblk
= dblkno
;
220 slp
->req
[trecno
].count
= avail
;
222 spcl
.c_tapea
+= avail
;
225 dblkno
+= avail
<< (tp_bshift
- dev_bshift
);
237 msg("write error on %s\n", tape
);
238 quit("Cannot recover\n");
241 msg("write error %d blocks into volume %d\n", blocksthisvol
, tapeno
);
242 broadcast("DUMP WRITE ERROR!\n");
243 if (!query("Do you want to restart?"))
245 msg("Closing this volume. Prepare to restart with new media;\n");
246 msg("this dump volume will be rewritten.\n");
257 quit("Broken pipe\n");
262 * Update xferrate stats
275 ttaken
= tnow
- tstart_volume
;
276 blocks
= spcl
.c_tapea
- tapea_volume
;
277 msg("Volume %d completed at: %s", tapeno
,
284 msg("Volume %d took %d:%02d:%02d\n", tapeno
,
285 ttaken
/ 3600, (ttaken
% 3600) / 60, ttaken
% 60);
286 msg("Volume %d transfer rate: %ld KB/s\n", tapeno
,
288 xferrate
+= blocks
/ ttaken
;
296 * information message upon receipt of SIGINFO
297 * (derived from optr.c::timeest())
300 statussig(int notused
)
304 int save_errno
= errno
;
306 if (blockswritten
< 500)
311 (void) time((time_t *) &tnow
);
313 deltat
= tstart_writing
- tnow
+ (1.0 * (tnow
- tstart_writing
))
314 / blockswritten
* tapesize
;
315 (void)snprintf(msgbuf
, sizeof(msgbuf
),
316 "%3.2f%% done at %ld KB/s, finished in %d:%02d\n",
317 (blockswritten
* 100.0) / tapesize
,
318 (spcl
.c_tapea
- tapea_volume
) / (tnow
- tstart_volume
),
319 (int)(deltat
/ 3600), (int)((deltat
% 3600) / 60));
320 write(STDERR_FILENO
, msgbuf
, strlen(msgbuf
));
331 int siz
= (char *)nextblock
- (char *)slp
->req
;
333 slp
->req
[trecno
].count
= 0; /* Sentinel */
335 if (atomic_write( slp
->fd
, (char *)slp
->req
, siz
) != siz
)
336 quit("error writing command pipe: %s\n", strerror(errno
));
337 slp
->sent
= 1; /* we sent a request, read the response later */
339 lastfirstrec
= slp
->firstrec
;
341 if (++slp
>= &slaves
[SLAVES
])
344 /* Read results back from next slave */
346 if (atomic_read( slp
->fd
, (char *)&got
, sizeof got
)
348 perror(" DUMP: error reading command pipe in master");
353 /* Check for end of tape */
354 if (got
< writesize
) {
355 msg("End of tape detected\n");
358 * Drain the results, don't care what the values were.
359 * If we read them here then trewind won't...
361 for (i
= 0; i
< SLAVES
; i
++) {
362 if (slaves
[i
].sent
) {
363 if (atomic_read( slaves
[i
].fd
,
364 (char *)&got
, sizeof got
)
366 perror(" DUMP: error reading command pipe in master");
380 if (spcl
.c_type
!= TS_END
) {
381 for (i
= 0; i
< spcl
.c_count
; i
++)
382 if (spcl
.c_addr
[i
] != 0)
385 slp
->count
= lastspclrec
+ blks
+ 1 - spcl
.c_tapea
;
386 slp
->tapea
= spcl
.c_tapea
;
387 slp
->firstrec
= lastfirstrec
+ ntrec
;
389 nextblock
= slp
->tblock
;
392 blockswritten
+= ntrec
;
393 blocksthisvol
+= ntrec
;
394 if (!pipeout
&& !unlimited
&& (blocksperfile
?
395 (blocksthisvol
>= blocksperfile
) : (asize
> tsize
))) {
408 for (f
= 0; f
< SLAVES
; f
++) {
410 * Drain the results, but unlike EOT we DO (or should) care
411 * what the return values were, since if we detect EOT after
412 * we think we've written the last blocks to the tape anyway,
413 * we have to replay those blocks with rollforward.
415 * fixme: punt for now.
417 if (slaves
[f
].sent
) {
418 if (atomic_read( slaves
[f
].fd
, (char *)&got
, sizeof got
)
420 perror(" DUMP: error reading command pipe in master");
424 if (got
!= writesize
) {
425 msg("EOT detected in last 2 tape records!\n");
426 msg("Use a longer tape, decrease the size estimate\n");
427 quit("or use no size estimate at all.\n");
430 (void) close(slaves
[f
].fd
);
432 while (wait((int *)NULL
) >= 0) /* wait for any signals from slaves */
438 msg("Closing %s\n", tape
);
443 while (rmtopen(tape
, 0) < 0)
449 (void) close(tapefd
);
450 while ((f
= open(tape
, 0)) < 0)
463 msg("Change Volumes: Mount volume #%d\n", tapeno
+1);
464 broadcast("CHANGE DUMP VOLUMES!\7\7\n");
466 while (!query("Is the new volume mounted and ready to go?"))
467 if (query("Do you want to abort?")) {
476 register struct req
*p
, *q
, *prev
;
477 register struct slave
*tslp
;
478 int i
, size
, savedtapea
, got
;
479 union u_spcl
*ntb
, *otb
;
484 tslp
= &slaves
[SLAVES
];
485 ntb
= (union u_spcl
*)tslp
->tblock
[1];
488 * Each of the N slaves should have requests that need to
489 * be replayed on the next tape. Use the extra slave buffers
490 * (slaves[SLAVES]) to construct request lists to be sent to
491 * each slave in turn.
493 for (i
= 0; i
< SLAVES
; i
++) {
495 otb
= (union u_spcl
*)slp
->tblock
;
498 * For each request in the current slave, copy it to tslp.
502 for (p
= slp
->req
; p
->count
> 0; p
+= p
->count
) {
505 *ntb
++ = *otb
++; /* copy the datablock also */
510 quit("rollforward: protocol botch");
522 nextblock
= tslp
->tblock
;
523 savedtapea
= spcl
.c_tapea
;
524 spcl
.c_tapea
= slp
->tapea
;
526 spcl
.c_tapea
= savedtapea
;
527 lastspclrec
= savedtapea
- 1;
529 size
= (char *)ntb
- (char *)q
;
530 if (atomic_write( slp
->fd
, (char *)q
, size
) != size
) {
531 perror(" DUMP: error writing command pipe");
536 lastfirstrec
= slp
->firstrec
;
538 if (++slp
>= &slaves
[SLAVES
])
543 if (prev
->dblk
!= 0) {
545 * If the last one was a disk block, make the
546 * first of this one be the last bit of that disk
549 q
->dblk
= prev
->dblk
+
550 prev
->count
* (TP_BSIZE
/ DEV_BSIZE
);
551 ntb
= (union u_spcl
*)tslp
->tblock
;
554 * It wasn't a disk block. Copy the data to its
555 * new location in the buffer.
558 *((union u_spcl
*)tslp
->tblock
) = *ntb
;
559 ntb
= (union u_spcl
*)tslp
->tblock
[1];
563 nextblock
= slp
->tblock
;
566 *(union u_spcl
*)(*(nextblock
)++) = *(union u_spcl
*)tslp
->tblock
;
573 * Clear the first slaves' response. One hopes that it
574 * worked ok, otherwise the tape is much too short!
577 if (atomic_read( slp
->fd
, (char *)&got
, sizeof got
)
579 perror(" DUMP: error reading command pipe in master");
584 if (got
!= writesize
) {
585 quit("EOT detected at start of the tape!\n");
591 if (spcl
.c_type
!= TS_END
) {
592 for (i
= 0; i
< spcl
.c_count
; i
++)
593 if (spcl
.c_addr
[i
] != 0)
597 slp
->firstrec
= lastfirstrec
+ ntrec
;
598 slp
->count
= lastspclrec
+ blks
+ 1 - spcl
.c_tapea
;
601 blockswritten
+= ntrec
;
602 blocksthisvol
+= ntrec
;
607 * We implement taking and restoring checkpoints on the tape level.
608 * When each tape is opened, a new process is created by forking; this
609 * saves all of the necessary context in the parent. The child
610 * continues the dump; the parent waits around, saving the context.
611 * If the child returns X_REWRITE, then it had problems writing that tape;
612 * this causes the parent to fork again, duplicating the context, and
613 * everything continues as if nothing had happened.
616 startnewtape(int top
)
624 void (*interrupt_save
) __P((int signo
));
625 #else /* __linux__ */
627 void (*interrupt_save
)();
629 sig_t interrupt_save
;
631 #endif /* __linux__ */
633 interrupt_save
= signal(SIGINT
, SIG_IGN
);
634 parentpid
= getpid();
635 tapea_volume
= spcl
.c_tapea
;
637 (void)time4(&tstart_volume
);
639 (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 if (waitpid
!= rshpid
)
666 msg("Parent %d waiting for child %d has another child %d return\n",
667 parentpid
, childpid
, waitpid
);
669 msg("Child %d returns LOB status %o\n",
670 childpid
, status
&0xFF);
672 status
= (status
>> 8) & 0xFF;
676 msg("Child %d finishes X_FINOK\n", childpid
);
679 msg("Child %d finishes X_ABORT\n", childpid
);
682 msg("Child %d finishes X_REWRITE\n", childpid
);
685 msg("Child %d finishes unknown %d\n",
696 goto restore_check_point
;
698 msg("Bad return code from dump: %d\n", status
);
702 } else { /* we are the child; just continue */
704 sleep(4); /* allow time for parent's message to get out */
705 msg("Child on Tape %d has parent %d, my pid = %d\n",
706 tapeno
+1, parentpid
, getpid());
709 * If we have a name like "/dev/rmt0,/dev/rmt1",
710 * use the name before the comma first, and save
711 * the remaining names for subsequent volumes.
713 tapeno
++; /* current tape sequence */
714 if (nexttape
|| strchr(tape
, ',')) {
715 if (nexttape
&& *nexttape
)
717 if ((p
= strchr(tape
, ',')) != NULL
) {
722 msg("Dumping volume %d on %s\n", tapeno
, tape
);
725 while ((tapefd
= (host
? rmtopen(tape
, 2) :
726 pipeout
? 1 : open(tape
, O_WRONLY
|O_CREAT
, 0666))) < 0)
728 while ((tapefd
= (pipeout
? 1 :
729 open(tape
, O_WRONLY
|O_CREAT
, 0666))) < 0)
732 msg("Cannot open output \"%s\".\n", tape
);
733 if (!query("Do you want to retry the open?"))
737 enslave(); /* Share open tape file descriptor with slaves */
742 newtape
++; /* new tape signal */
743 spcl
.c_count
= slp
->count
;
745 * measure firstrec in TP_BSIZE units since restore doesn't
746 * know the correct ntrec value...
748 spcl
.c_firstrec
= slp
->firstrec
;
750 spcl
.c_type
= TS_TAPE
;
751 spcl
.c_flags
|= DR_NEWHEADER
;
752 writeheader((ino_t
)slp
->inode
);
753 spcl
.c_flags
&=~ DR_NEWHEADER
;
754 msg("Volume %d started at: %s", tapeno
,
756 ctime4(&tstart_volume
));
758 ctime(&tstart_volume
));
761 msg("Volume %d begins with blocks from inode %d\n",
770 if (master
!= 0 && master
!= getpid())
771 /* Signals master to call dumpabort */
772 (void) kill(master
, SIGTERM
);
775 msg("The ENTIRE dump is aborted.\n");
788 msg("pid = %d exits with status %d\n", getpid(), status
);
794 * proceed - handler for SIGUSR2, used to synchronize IO between the slaves.
801 siglongjmp(jmpbuf
, 1);
809 #ifdef LINUX_FORK_BUG
817 signal(SIGTERM
, dumpabort
); /* Slave sends SIGTERM on dumpabort() */
818 signal(SIGPIPE
, sigpipe
);
819 signal(SIGUSR1
, tperror
); /* Slave sends SIGUSR1 on tape errors */
820 signal(SIGUSR2
, proceed
); /* Slave sends SIGUSR2 to next slave */
822 for (i
= 0; i
< SLAVES
; i
++) {
823 if (i
== slp
- &slaves
[0]) {
829 if (socketpair(AF_UNIX
, SOCK_STREAM
, 0, cmd
) < 0 ||
830 (slaves
[i
].pid
= fork()) < 0)
831 quit("too many slaves, %d (recompile smaller): %s\n",
834 slaves
[i
].fd
= cmd
[1];
836 if (slaves
[i
].pid
== 0) { /* Slave starts up here */
837 for (j
= 0; j
<= i
; j
++)
838 (void) close(slaves
[j
].fd
);
839 signal(SIGINT
, SIG_IGN
); /* Master handles this */
841 signal(SIGINFO
, SIG_IGN
);
844 #ifdef LINUX_FORK_BUG
845 if (atomic_write( cmd
[0], (char *) &i
, sizeof i
)
847 quit("master/slave protocol botched 3\n");
854 #ifdef LINUX_FORK_BUG
856 * Wait for all slaves to _actually_ start to circumvent a bug in
857 * Linux kernels >= 2.1.3 where a signal sent to a child that hasn't
858 * returned from fork() causes a SEGV in the child process
860 for (i
= 0; i
< SLAVES
; i
++)
861 if (atomic_read( slaves
[i
].fd
, (char *) &j
, sizeof j
) != sizeof j
)
862 quit("master/slave protocol botched 4\n");
865 for (i
= 0; i
< SLAVES
; i
++)
866 (void) atomic_write( slaves
[i
].fd
,
867 (char *) &slaves
[(i
+ 1) % SLAVES
].pid
,
868 sizeof slaves
[0].pid
);
878 for (i
= 0; i
< SLAVES
; i
++)
879 if (slaves
[i
].pid
> 0) {
880 (void) kill(slaves
[i
].pid
, SIGKILL
);
886 * Synchronization - each process has a lockfile, and shares file
887 * descriptors to the following process's lockfile. When our write
888 * completes, we release our lock on the following process's lock-
889 * file, allowing the following process to lock it and proceed. We
890 * get the lock back for the next cycle by swapping descriptors.
893 doslave(int cmd
, int slave_number
)
896 int nextslave
, size
, eot_count
;
897 volatile int wrote
= 0;
904 * Need our own seek pointer.
906 (void) close(diskfd
);
907 if ((diskfd
= open(disk
, O_RDONLY
)) < 0)
908 quit("slave couldn't reopen disk: %s\n", strerror(errno
));
911 retval
= ext2fs_open(disk
, 0, 0, 0, unix_io_manager
, &fs
);
913 quit("slave couldn't reopen disk: %s\n", strerror(errno
));
914 #endif /* __linux__ */
917 * Need the pid of the next slave in the loop...
919 if ((nread
= atomic_read( cmd
, (char *)&nextslave
, sizeof nextslave
))
920 != sizeof nextslave
) {
921 quit("master/slave protocol botched - didn't get pid of next slave.\n");
925 * Get list of blocks to dump, read the blocks into tape buffer
927 while ((nread
= atomic_read( cmd
, (char *)slp
->req
, reqsiz
)) == reqsiz
) {
928 register struct req
*p
= slp
->req
;
930 for (trecno
= 0; trecno
< ntrec
;
931 trecno
+= p
->count
, p
+= p
->count
) {
933 bread(p
->dblk
, slp
->tblock
[trecno
],
934 p
->count
* TP_BSIZE
);
936 if (p
->count
!= 1 || atomic_read( cmd
,
937 (char *)slp
->tblock
[trecno
],
938 TP_BSIZE
) != TP_BSIZE
)
939 quit("master/slave protocol botched.\n");
942 if (setjmp(jmpbuf
) == 0) {
950 /* Try to write the data... */
955 while (eot_count
< 10 && size
< writesize
) {
958 wrote
= rmtwrite(slp
->tblock
[0]+size
,
962 wrote
= write(tapefd
, slp
->tblock
[0]+size
,
965 printf("slave %d wrote %d\n", slave_number
, wrote
);
975 if (size
!= writesize
)
976 printf("slave %d only wrote %d out of %d bytes and gave up.\n",
977 slave_number
, size
, writesize
);
981 * Handle ENOSPC as an EOT condition.
983 if (wrote
< 0 && errno
== ENOSPC
) {
992 (void) kill(master
, SIGUSR1
);
993 sigemptyset(&sigset
);
998 * pass size of write back to master
1001 (void) atomic_write( cmd
, (char *)&size
, sizeof size
);
1005 * If partial write, don't want next slave to go.
1006 * Also jolts him awake.
1008 (void) kill(nextslave
, SIGUSR2
);
1011 quit("error reading command pipe: %s\n", strerror(errno
));
1015 * Since a read from a pipe may not return all we asked for,
1016 * or a write may not write all we ask if we get a signal,
1017 * loop until the count is satisfied (or error).
1020 atomic_read(int fd
, void *buf
, size_t count
)
1022 int got
, need
= count
;
1024 while ((got
= read(fd
, buf
, need
)) > 0 && (need
-= got
) > 0)
1026 return (got
< 0 ? got
: count
- need
);
1030 * Since a read from a pipe may not return all we asked for,
1031 * or a write may not write all we ask if we get a signal,
1032 * loop until the count is satisfied (or error).
1035 atomic_write(int fd
, const void *buf
, size_t count
)
1037 int got
, need
= count
;
1039 while ((got
= write(fd
, buf
, need
)) > 0 && (need
-= got
) > 0)
1041 return (got
< 0 ? got
: count
- need
);