]> git.wh0rd.org - dump.git/blobdiff - dump/tape.c
Andreas Dilger fixes (CPP, ext2 features, const char etc).
[dump.git] / dump / tape.c
index 45828a52f742e782b48582be691317487a9e8070..f43c3a20a9b3d4aae071afcb90ca90bd3641ebac 100644 (file)
@@ -2,7 +2,8 @@
  *     Ported to Linux's Second Extended File System as part of the
  *     dump and restore backup suit
  *     Remy Card <card@Linux.EU.Org>, 1994-1997
- *     Stelian Pop <pop@cybercable.fr>, 1999-2000
+ *     Stelian Pop <pop@noos.fr>, 1999-2000
+ *     Stelian Pop <pop@noos.fr> - AlcĂ´ve <www.alcove.fr>, 2000
  */
 
 /*-
 
 #ifndef lint
 static const char rcsid[] =
-       "$Id: tape.c,v 1.17 2000/03/10 10:03:09 stelian Exp $";
+       "$Id: tape.c,v 1.34 2001/03/19 13:22:48 stelian Exp $";
 #endif /* not lint */
 
+#include <config.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <setjmp.h>
+#include <signal.h>
+#include <stdio.h>
+#include <compaterr.h>
+#ifdef __STDC__
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#else
+int    write(), read();
+#endif
+
 #ifdef __linux__
 #include <sys/types.h>
+#include <time.h>
 #include <linux/types.h>
 #endif
 #include <sys/param.h>
@@ -53,9 +70,9 @@ static const char rcsid[] =
 #include <sys/wait.h>
 #ifdef __linux__
 #include <linux/ext2_fs.h>
+#include <ext2fs/ext2fs.h>
 #include <bsdcompat.h>
-#else  /* __linux__ */
-#ifdef sunos
+#elif defined sunos
 #include <sys/vnode.h>
 
 #include <ufs/fs.h>
@@ -63,28 +80,13 @@ static const char rcsid[] =
 #else
 #include <ufs/ufs/dinode.h>
 #include <ufs/ffs/fs.h>
-#endif
 #endif /* __linux__ */
 
 #include <protocols/dumprestore.h>
 
-#include <errno.h>
-#include <fcntl.h>
-#include <setjmp.h>
-#include <signal.h>
-#include <stdio.h>
-#include <compaterr.h>
-#ifdef __STDC__
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#else
-int    write(), read();
-#endif
-
-#ifdef __linux__
-#include <ext2fs/ext2fs.h>
-#endif
+#ifdef HAVE_ZLIB
+#include <zlib.h>
+#endif /* HAVE_ZLIB */
 
 #include "dump.h"
 
@@ -99,6 +101,7 @@ extern       char *host;
 char   *nexttape;
 extern  pid_t rshpid;
 int    eot_code = 1;
+long long tapea_bytes = 0;     /* bytes_written at start of current volume */
 
 static ssize_t atomic_read __P((int, void *, size_t));
 static ssize_t atomic_write __P((int, const void *, size_t));
@@ -123,6 +126,11 @@ struct req {
 };
 int reqsiz;
 
+struct slave_results {
+       ssize_t unclen;         /* uncompressed length */
+       ssize_t clen;           /* compressed length */
+};
+
 #define SLAVES 3               /* 1 slave writing, 1 reading, 1 for slack */
 struct slave {
        int tapea;              /* header number at start of this chunk */
@@ -144,7 +152,7 @@ static time_t tstart_volume;        /* time of volume start */
 static int tapea_volume;       /* value of spcl.c_tapea at volume start */
 
 int master;            /* pid of master, for sending error signals */
-int tenths;            /* length of tape used per block written */
+int tenths;            /* length of tape overhead per block written */
 static int caught;     /* have we caught the signal to proceed? */
 static int ready;      /* have we reached the lock point without having */
                        /* received the SIGUSR2 signal from the prev slave? */
@@ -167,8 +175,11 @@ alloctape(void)
         * 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);
+               tenths = (cartridge ? 16 : density == 625 ? 5 : 8);
+       else {
+               tenths = 0;
+               density = 1;
+       }
        /*
         * Allocate tape buffer contiguous with the array of instruction
         * packets, so flushtape() can write them together with one write().
@@ -234,24 +245,27 @@ dumpblock(daddr_t blkno, int size)
 int    nogripe = 0;
 
 static void
-tperror(int signo)
+tperror(int errnum)
 {
 
        if (pipeout) {
-               msg("write error on %s\n", tape);
+               msg("write error on %s: %s\n", tape, strerror(errnum));
                quit("Cannot recover\n");
                /* NOTREACHED */
        }
-       msg("write error %d blocks into volume %d\n", blocksthisvol, tapeno);
+       msg("write error %d blocks into volume %d: %s\n", blocksthisvol, tapeno, strerror(errnum));
        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);
+       if (query("Do you want to rewrite this volume?")) {
+               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);
+       }
+       if (query("Do you want to start the next tape?"))
+               return;
+       dumpabort(0);
 }
 
 static void
@@ -284,46 +298,76 @@ do_stats(void)
 #else
                                          ctime(&tnow));
 #endif
+       if (! compressed)
+               msg("Volume %d %ld tape blocks (%.2fMB)\n", tapeno, 
+                       blocks, ((double)blocks * TP_BSIZE / 1048576));
        if (ttaken > 0) {
+               long volkb = (bytes_written - tapea_bytes) / 1024;
+               long txfrate = volkb / ttaken;
                msg("Volume %d took %d:%02d:%02d\n", tapeno,
                        ttaken / 3600, (ttaken % 3600) / 60, ttaken % 60);
                msg("Volume %d transfer rate: %ld KB/s\n", tapeno,
-                       blocks / ttaken);
-               xferrate += blocks / ttaken;
+                       txfrate);
+               xferrate += txfrate;
+               if (compressed) {
+                       double rate = .0005 + (double) blocks / (double) volkb;
+                       msg("Volume %d %ldKB uncompressed, %ldKB compressed,"
+                               " compression ratio %1.3f\n",
+                               tapeno, blocks, volkb, rate);
+               }
        }
        return(tnow);
 }
 
+char *
+mktimeest(time_t tnow)
+{
+       static char msgbuf[128];
+       time_t deltat;
+
+       msgbuf[0] = '\0';
+
+       if (blockswritten < 500)
+               return NULL;
+       if (blockswritten > tapesize)
+               tapesize = blockswritten;
+       deltat = tstart_writing - tnow + (1.0 * (tnow - tstart_writing))
+               / blockswritten * tapesize;
+       if (tnow > tstart_volume)
+               (void)snprintf(msgbuf, sizeof(msgbuf),
+                       "%3.2f%% done at %ld KB/s, finished in %d:%02d\n",
+                       (blockswritten * 100.0) / tapesize,
+                       (spcl.c_tapea - tapea_volume) / (tnow - tstart_volume),
+                       (int)(deltat / 3600), (int)((deltat % 3600) / 60));
+       else
+               (void)snprintf(msgbuf, sizeof(msgbuf),
+                       "%3.2f%% done, finished in %d:%02d\n",
+                       (blockswritten * 100.0) / tapesize,
+                       (int)(deltat / 3600), (int)((deltat % 3600) / 60));
+
+       return msgbuf;
+}
+
 #if defined(SIGINFO)
 /*
  * statussig --
  *     information message upon receipt of SIGINFO
- *     (derived from optr.c::timeest())
  */
 void
 statussig(int notused)
 {
-       time_t  tnow, deltat;
-       char    msgbuf[128];
+       time_t tnow;
        int save_errno = errno;
+       char *buf;
 
-       if (blockswritten < 500)
-               return;
 #ifdef __linux__
        (void) time4(&tnow);
 #else
        (void) time((time_t *) &tnow);
 #endif
-       if (blockswritten > tapesize)
-               tapesize = blockswritten;
-       deltat = tstart_writing - tnow + (1.0 * (tnow - tstart_writing))
-               / blockswritten * tapesize;
-       (void)snprintf(msgbuf, sizeof(msgbuf),
-               "%3.2f%% done at %ld KB/s, finished in %d:%02d\n",
-               (blockswritten * 100.0) / tapesize,
-               (spcl.c_tapea - tapea_volume) / (tnow - tstart_volume),
-               (int)(deltat / 3600), (int)((deltat % 3600) / 60));
-       write(STDERR_FILENO, msgbuf, strlen(msgbuf));
+       buf = mktimeest(tnow);
+       if (buf)
+               write(STDERR_FILENO, buf, strlen(buf));
        errno = save_errno;
 }
 #endif
@@ -333,6 +377,7 @@ flushtape(void)
 {
        int i, blks, got;
        long lastfirstrec;
+       struct slave_results returned;
 
        int siz = (char *)nextblock - (char *)slp->req;
 
@@ -349,15 +394,23 @@ flushtape(void)
 
        /* Read results back from next slave */
        if (slp->sent) {
-               if (atomic_read( slp->fd, (char *)&got, sizeof got)
-                   != sizeof got) {
+               if (atomic_read( slp->fd, (char *)&returned, sizeof returned)
+                   != sizeof returned) {
                        perror("  DUMP: error reading command pipe in master");
                        dumpabort(0);
                }
+               got = returned.unclen;
+               bytes_written += returned.clen;
+               if (returned.unclen == returned.clen)
+                       uncomprblks++;
                slp->sent = 0;
 
+               /* Check for errors */
+               if (got < 0)
+                       tperror(-got);
+               
                /* Check for end of tape */
-               if (got < writesize) {
+               if (got == 0) {
                        msg("End of tape detected\n");
 
                        /*
@@ -367,8 +420,8 @@ flushtape(void)
                        for (i = 0; i < SLAVES; i++) {
                                if (slaves[i].sent) {
                                        if (atomic_read( slaves[i].fd,
-                                           (char *)&got, sizeof got)
-                                           != sizeof got) {
+                                           (char *)&returned, sizeof returned)
+                                           != sizeof returned) {
                                                perror("  DUMP: error reading command pipe in master");
                                                dumpabort(0);
                                        }
@@ -394,7 +447,7 @@ flushtape(void)
        slp->inode = curino;
        nextblock = slp->tblock;
        trecno = 0;
-       asize += tenths;
+       asize += tenths + returned.clen / density;
        blockswritten += ntrec;
        blocksthisvol += ntrec;
        if (!pipeout && !unlimited && (blocksperfile ?
@@ -422,7 +475,11 @@ int system_command(const char *command, const char *device, int volnum) {
        if (pid == 0) {
                setuid(getuid());
                setgid(getgid());
+#if OLD_STYLE_FSCRIPT
+               snprintf(commandstr, sizeof(commandstr), "%s", command);
+#else
                snprintf(commandstr, sizeof(commandstr), "%s %s %d", command, device, volnum);
+#endif
                commandstr[sizeof(commandstr) - 1] = '\0';
                execl("/bin/sh", "sh", "-c", commandstr, NULL);
                perror("  DUMP: unable to execute shell");
@@ -448,6 +505,7 @@ trewind(void)
 {
        int f;
        int got;
+       struct slave_results returned;
 
        for (f = 0; f < SLAVES; f++) {
                /*
@@ -459,13 +517,21 @@ trewind(void)
                 * fixme: punt for now.
                 */
                if (slaves[f].sent) {
-                       if (atomic_read( slaves[f].fd, (char *)&got, sizeof got)
-                           != sizeof got) {
+                       if (atomic_read( slaves[f].fd, (char *)&returned, sizeof returned)
+                           != sizeof returned) {
                                perror("  DUMP: error reading command pipe in master");
                                dumpabort(0);
                        }
+                       got = returned.unclen;
+                       bytes_written += returned.clen;
+                       if (returned.unclen == returned.clen)
+                               uncomprblks++;
                        slaves[f].sent = 0;
-                       if (got != writesize) {
+
+                       if (got < 0)
+                               tperror(-got);
+
+                       if (got == 0) {
                                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");
@@ -488,16 +554,15 @@ trewind(void)
                        rmtclose();
                }
                else 
-#else
+#endif
                {
                        (void) close(tapefd);
                        while ((f = open(tape, 0)) < 0)
                                sleep (10);
                        (void) close(f);
                }
-#endif
                eot_code = 1;
-               if (eot_script) {
+               if (eot_script && spcl.c_type != TS_END) {
                        msg("Launching %s\n", eot_script);
                        eot_code = system_command(eot_script, tape, tapeno);
                }
@@ -534,6 +599,7 @@ rollforward(void)
        register struct slave *tslp;
        int i, size, savedtapea, got;
        union u_spcl *ntb, *otb;
+       struct slave_results returned;
 #ifdef __linux__
        int blks;
        long lastfirstrec;
@@ -618,12 +684,13 @@ rollforward(void)
        }
        slp->req[0] = *q;
        nextblock = slp->tblock;
-       if (q->dblk == 0)
+       if (q->dblk == 0) {
 #ifdef __linux__
-               *(union u_spcl *)(*(nextblock)++) = *(union u_spcl *)tslp->tblock;
-#else
-               nextblock++;
+       /* XXX post increment triggers an egcs-1.1.2-12 bug on alpha/sparc */
+               *(union u_spcl *)(*nextblock) = *(union u_spcl *)tslp->tblock;
 #endif
+               nextblock++;
+       }
        trecno = 1;
 
        /*
@@ -631,14 +698,21 @@ rollforward(void)
         * worked ok, otherwise the tape is much too short!
         */
        if (slp->sent) {
-               if (atomic_read( slp->fd, (char *)&got, sizeof got)
-                   != sizeof got) {
+               if (atomic_read( slp->fd, (char *)&returned, sizeof returned)
+                   != sizeof returned) {
                        perror("  DUMP: error reading command pipe in master");
                        dumpabort(0);
                }
+               got = returned.unclen;
+               bytes_written += returned.clen;
+               if (returned.clen == returned.unclen)
+                       uncomprblks++;
                slp->sent = 0;
 
-               if (got != writesize) {
+               if (got < 0)
+                       tperror(-got);
+
+               if (got == 0) {
                        quit("EOT detected at start of the tape!\n");
                }
        }
@@ -654,7 +728,7 @@ rollforward(void)
        slp->firstrec = lastfirstrec + ntrec;
        slp->count = lastspclrec + blks + 1 - spcl.c_tapea;
        slp->inode = curino;
-       asize += tenths;
+       asize += tenths + returned.clen / density;
        blockswritten += ntrec;
        blocksthisvol += ntrec;
 #endif
@@ -677,19 +751,24 @@ startnewtape(int top)
        int     status;
        int     waitpid;
        char    *p;
+
 #ifdef __linux__
-       void    (*interrupt_save)  __P((int signo));
+       sigset_t sigs;
+       sigemptyset(&sigs);
+       sigaddset(&sigs, SIGINT);
+       sigprocmask(SIG_BLOCK, &sigs, NULL);
 #else  /* __linux__ */
 #ifdef sunos
        void    (*interrupt_save)();
 #else
        sig_t   interrupt_save;
 #endif
+       interrupt_save = signal(SIGINT, SIG_IGN);
 #endif /* __linux__ */
 
-       interrupt_save = signal(SIGINT, SIG_IGN);
        parentpid = getpid();
        tapea_volume = spcl.c_tapea;
+       tapea_bytes = bytes_written;
 #ifdef __linux__
        (void)time4(&tstart_volume);
 #else
@@ -697,7 +776,11 @@ startnewtape(int top)
 #endif
 
 restore_check_point:
+#ifdef __linux__
+       sigprocmask(SIG_UNBLOCK, &sigs, NULL);
+#else
        (void)signal(SIGINT, interrupt_save);
+#endif
        /*
         *      All signals are inherited...
         */
@@ -713,7 +796,11 @@ restore_check_point:
                 *      until the child doing all of the work returns.
                 *      don't catch the interrupt
                 */
+#ifdef __linux__
+               sigprocmask(SIG_BLOCK, &sigs, NULL);
+#else
                signal(SIGINT, SIG_IGN);
+#endif
 #ifdef TDEBUG
                msg("Tape: %d; parent process: %d child process %d\n",
                        tapeno+1, parentpid, childpid);
@@ -814,6 +901,8 @@ restore_check_point:
                spcl.c_volume++;
                spcl.c_type = TS_TAPE;
                spcl.c_flags |= DR_NEWHEADER;
+               if (compressed)
+                       spcl.c_flags |= DR_COMPRESSED;
                writeheader((ino_t)slp->inode);
                spcl.c_flags &=~ DR_NEWHEADER;
                msg("Volume %d started at: %s", tapeno, 
@@ -861,7 +950,6 @@ Exit(int status)
 static void
 proceed(int signo)
 {
-
        if (ready)
                siglongjmp(jmpbuf, 1);
        caught++;
@@ -879,10 +967,17 @@ enslave(void)
 
        master = getpid();
 
-       signal(SIGTERM, dumpabort);  /* Slave sends SIGTERM on dumpabort() */
-       signal(SIGPIPE, sigpipe);
-       signal(SIGUSR1, tperror);    /* Slave sends SIGUSR1 on tape errors */
-       signal(SIGUSR2, proceed);    /* Slave sends SIGUSR2 to next slave */
+    {  struct sigaction sa;
+       memset(&sa, 0, sizeof sa);
+       sigemptyset(&sa.sa_mask);
+       sa.sa_handler = dumpabort;
+       sigaction(SIGTERM, &sa, NULL); /* Slave sends SIGTERM on dumpabort() */
+       sa.sa_handler = sigpipe;
+       sigaction(SIGPIPE, &sa, NULL);
+       sa.sa_handler = proceed;
+       sa.sa_flags = SA_RESTART;
+       sigaction(SIGUSR2, &sa, NULL); /* Slave sends SIGUSR2 to next slave */
+   }
 
        for (i = 0; i < SLAVES; i++) {
                if (i == slp - &slaves[0]) {
@@ -899,12 +994,15 @@ enslave(void)
                slaves[i].fd = cmd[1];
                slaves[i].sent = 0;
                if (slaves[i].pid == 0) {           /* Slave starts up here */
+                       sigset_t sigs;
                        for (j = 0; j <= i; j++)
                                (void) close(slaves[j].fd);
-                       signal(SIGINT, SIG_IGN);    /* Master handles this */
+                       sigemptyset(&sigs);
+                       sigaddset(&sigs, SIGINT);  /* Master handles this */
 #if defined(SIGINFO)
-                       signal(SIGINFO, SIG_IGN);
+                       sigaddset(&sigs, SIGINFO);
 #endif
+                       sigprocmask(SIG_BLOCK, &sigs, NULL);
 
 #ifdef LINUX_FORK_BUG
                        if (atomic_write( cmd[0], (char *) &i, sizeof i)
@@ -948,19 +1046,25 @@ killall(void)
 }
 
 /*
- * 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.
+ * Synchronization - each process waits for a SIGUSR2 from the
+ * previous process before writing to the tape, and sends SIGUSR2
+ * to the next process when the tape write completes. On tape errors
+ * a SIGUSR1 is sent to the master which then terminates all of the
+ * slaves.
  */
 static void
 doslave(int cmd, int slave_number)
 {
        register int nread;
-       int nextslave, size, eot_count;
+       int nextslave, size, eot_count, bufsize;
        volatile int wrote = 0;
-       sigset_t sigset;
+       char *buffer;
+#ifdef HAVE_ZLIB
+       struct tapebuf *comp_buf = NULL;
+       int compresult, complevel = 6, do_compress = 0;
+       unsigned long worklen;
+#endif /* HAVE_ZLIB */
+       struct slave_results returns;
 #ifdef __linux__
        errcode_t retval;
 #endif
@@ -986,6 +1090,16 @@ doslave(int cmd, int slave_number)
                quit("master/slave protocol botched - didn't get pid of next slave.\n");
        }
 
+#ifdef HAVE_ZLIB
+       /* if we're doing a compressed dump, allocate the compress buffer */
+       if (compressed) {
+               comp_buf = malloc(sizeof(struct tapebuf) + TP_BSIZE + writesize);
+               if (comp_buf == NULL)
+                       quit("couldn't allocate a compress buffer.\n");
+               comp_buf->flags = 0;
+       }
+#endif /* HAVE_ZLIB */
+
        /*
         * Get list of blocks to dump, read the blocks into tape buffer
         */
@@ -994,17 +1108,17 @@ doslave(int cmd, int slave_number)
 
                for (trecno = 0; trecno < ntrec;
                     trecno += p->count, p += p->count) {
-                       if (p->dblk) {
+                       if (p->dblk) {  /* read a disk block */
                                bread(p->dblk, slp->tblock[trecno],
                                        p->count * TP_BSIZE);
-                       } else {
+                       } else {        /* read record from pipe */
                                if (p->count != 1 || atomic_read( cmd,
                                    (char *)slp->tblock[trecno],
                                    TP_BSIZE) != TP_BSIZE)
                                       quit("master/slave protocol botched.\n");
                        }
                }
-               if (setjmp(jmpbuf) == 0) {
+               if (sigsetjmp(jmpbuf, 1) == 0) {
                        ready = 1;
                        if (!caught)
                                (void) pause();
@@ -1016,16 +1130,56 @@ doslave(int cmd, int slave_number)
                wrote = 0;
                eot_count = 0;
                size = 0;
+               buffer = (char *) slp->tblock[0];       /* set write pointer */
+               bufsize = writesize;                    /* length to write */
+               returns.clen = returns.unclen = bufsize;
+
+#ifdef HAVE_ZLIB
+               /* 
+                * The first NR_SLAVE blocks are not compressed.
+                * When writing a compressed dump, each block is
+                * written from struct tapebuf with an 4 byte prefix
+                * followed by the data. This can be less than
+                * writesize. Restore, on a short read, can compare the
+                * length read to the compressed length in the header
+                * to verify that the read was good. Blocks which don't
+                * compress well are written uncompressed.
+                */
+
+               if (compressed) {
+                       comp_buf->length = bufsize;
+                       worklen = TP_BSIZE + writesize;
+                       if (do_compress)
+                               compresult = compress2(comp_buf->buf, &worklen,
+                                       (char *)slp->tblock[0], writesize, complevel);
+                       if (compresult == Z_OK && worklen <= writesize-32) {
+                               /* write the compressed buffer */
+                               comp_buf->length = worklen;
+                               comp_buf->compressed = 1;
+                               buffer = (char *) comp_buf;
+                               returns.clen = bufsize = worklen + sizeof(struct tapebuf);
+                       }
+                       else {
+                               /* write the data uncompressed */
+                               comp_buf->length = writesize;
+                               comp_buf->compressed = 0;
+                               buffer = (char *) comp_buf;
+                               returns.clen = bufsize = writesize + sizeof(struct tapebuf);
+                               returns.unclen = returns.clen;
+                               memcpy(comp_buf->buf, (char *)slp->tblock[0], writesize);
+                       }
+               }
+               /* compress the remaining blocks */
+               do_compress = compressed;
+#endif /* HAVE_ZLIB */
 
-               while (eot_count < 10 && size < writesize) {
+               while (eot_count < 10 && size < bufsize) {
 #ifdef RDUMP
                        if (host)
-                               wrote = rmtwrite(slp->tblock[0]+size,
-                                   writesize-size);
+                               wrote = rmtwrite(buffer + size, bufsize - size);
                        else
 #endif
-                               wrote = write(tapefd, slp->tblock[0]+size,
-                                   writesize-size);
+                               wrote = write(tapefd, buffer + size, bufsize - size);
 #ifdef WRITEDEBUG
                        printf("slave %d wrote %d\n", slave_number, wrote);
 #endif
@@ -1037,9 +1191,9 @@ doslave(int cmd, int slave_number)
                }
 
 #ifdef WRITEDEBUG
-               if (size != writesize)
+               if (size != bufsize)
                 printf("slave %d only wrote %d out of %d bytes and gave up.\n",
-                    slave_number, size, writesize);
+                    slave_number, size, bufsize);
 #endif
 
                /*
@@ -1051,24 +1205,22 @@ doslave(int cmd, int slave_number)
                }
 
                if (eot_count > 0)
-                       size = 0;
+                       returns.clen = returns.unclen = 0;
 
-               if (wrote < 0) {
-                       (void) kill(master, SIGUSR1);
-                       sigemptyset(&sigset);
-                       for (;;)
-                               sigsuspend(&sigset);
-               } else {
-                       /*
-                        * pass size of write back to master
-                        * (for EOT handling)
-                        */
-                       (void) atomic_write( cmd, (char *)&size, sizeof size);
-               }
+               /*
+                * pass errno back to master for special handling
+                */
+               if (wrote < 0)
+                       returns.unclen = -errno;
+
+               /*
+                * pass size of data and size of write back to master
+                * (for EOT handling)
+                */
+               (void) atomic_write( cmd, (char *)&returns, sizeof returns);
 
                /*
-                * If partial write, don't want next slave to go.
-                * Also jolts him awake.
+                * Signal the next slave to go.
                 */
                (void) kill(nextslave, SIGUSR2);
        }