2.11BSD/src/sbin/dump/dumptape.c

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#if	!defined(lint) && defined(DOSCCS)
static char sccsid[] = "@(#)dumptape.c	5.5.1 (2.11BSD) 1996/2/7";
#endif

#include <sys/file.h>
#include "dump.h"

char	(*tblock)[DEV_BSIZE];	/* Pointer to malloc()ed buffer for tape */
#define	writesize (NTREC * DEV_BSIZE) /* Size of malloc()ed buffer for tape */
int	trecno = 0;
#ifdef RDUMP
extern char *host;
int	rmtopen(), rmtwrite();
void	rmtclose();
#endif RDUMP
extern int read(), write();

/*
 * Concurrent dump mods (Caltech) - disk block reading and tape writing
 * are exported to several slave processes.  While one slave writes the
 * tape, the others read disk blocks; they pass control of the tape in
 * a ring via flock().	The parent process traverses the filesystem and
 * sends spclrec()'s and lists of daddr's to the slaves via pipes.
 */
struct req {			/* instruction packets sent to slaves */
	daddr_t dblk;
	int count;
} *req;
#define reqsiz (NTREC * sizeof (struct req))

/*
 * this is allocated here becaue malloc can all too easily fail later on.
 * IF anymore functionality is added to 'dump' then the bitmaps will have
 * to be moved to a file and paged.  
*/
	char	___xxx[reqsiz + writesize];

#define SLAVES 3		/* 1 slave writing, 1 reading, 1 for slack */
int slavefd[SLAVES];		/* pipes from master to each slave */
int slavepid[SLAVES];		/* used by killall() */
int rotor;			/* next slave to be instructed */
int master;			/* pid of master, for sending error signals */
u_int tenths;			/* length of tape used per block written */

alloctape()
{

	/*
	 * 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.
	 */
	tenths = writesize/density + (density == 625 ? 5 : 8);
	/*
	 * Allocate tape buffer contiguous with the array of instruction
	 * packets, so flusht() can write them together with one write().
	 */
	req = (struct req *)___xxx;
	if (req == NULL)
		return(0);
	tblock = (char (*)[DEV_BSIZE]) &req[NTREC];
	req = (struct req *)tblock - NTREC;
	return(1);
}


taprec(dp)
	char *dp;
{
	req[trecno].dblk = (daddr_t)0;
	req[trecno].count = 1;
	bcopy(dp, tblock, DEV_BSIZE); tblock++;
/*	*(union u_spcl *)(*tblock++) = *(union u_spcl *)dp;	/* movc3 */
	trecno++;
	spcl.c_tapea++;
	if(trecno >= NTREC)
		flusht();
}

tapsrec(blkno)
	daddr_t blkno;
{

	if (blkno == 0)
		return;
	req[trecno].dblk = blkno;
	req[trecno].count = 1;
	trecno++;
	spcl.c_tapea++;
	if (trecno >= NTREC)
		flusht();
}

int	nogripe = 0;

tperror() {
	if (pipeout) {
		msg("Tape write error on %s\n", tape);
		msg("Cannot recover\n");
		dumpabort();
		/* NOTREACHED */
	}
	msg("Tape write error %ld feet into tape %d\n", asize/120L, tapeno);
	broadcast("TAPE ERROR!\n");
	if (!query("Do you want to restart?"))
		dumpabort();
	msg("This tape will rewind.  After it is rewound,\n");
	msg("replace the faulty tape with a new one;\n");
	msg("this dump volume will be rewritten.\n");
	killall();
	nogripe = 1;
	close_rewind();
	Exit(X_REWRITE);
}

sigpipe()
{

	msg("Broken pipe\n");
	dumpabort();
}

flusht()
{
	int siz = (char *)tblock - (char *)req;

	if (atomic(write, slavefd[rotor], req, siz) != siz) {
		perror("  DUMP: error writing command pipe");
		dumpabort();
	}
	if (++rotor >= SLAVES) rotor = 0;
	tblock = (char (*)[DEV_BSIZE]) &req[NTREC];
	trecno = 0;
	asize += tenths;
	blockswritten += NTREC;
	if (!pipeout && asize > tsize) {
		close_rewind();
		otape();
	}
	timeest();
}

tape_rewind()
{
	int f;

	if (pipeout)
		return;
	for (f = 0; f < SLAVES; f++)
		close(slavefd[f]);
	while (wait(NULL) >= 0)    ;	/* wait for any signals from slaves */
	msg("Closing %s\n", tape);
#ifdef RDUMP
	if (host) {
		rmtclose();
		while (rmtopen(tape, 0) < 0)
			sleep(10);
		rmtclose();
		return;
	}
#endif RDUMP
	close(to);
	while ((f = open(tape, 0)) < 0)
		sleep (10);
	close(f);
}

close_rewind()
{
	tape_rewind();
	if (!nogripe) {
		msg("Change Tapes: Mount tape #%d\n", tapeno+1);
		broadcast("CHANGE TAPES!\7\7\n");
	}
	while (!query("Is the new tape mounted and ready to go?"))
		if (query("Do you want to abort?")) {
			dumpabort();
			/*NOTREACHED*/
		}
}

/*
 *	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.
 */

otape()
{
	int	parentpid;
	int	childpid;
	int	status;
	int	waitpid;
	int	(*interrupt)() = signal(SIGINT, SIG_IGN);

	parentpid = getpid();

    restore_check_point:
	signal(SIGINT, interrupt);
	/*
	 *	All signals are inherited...
	 */
	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
		while ((waitpid = wait(&status)) != childpid)
			msg("Parent %d waiting for child %d has another child %d return\n",
				parentpid, childpid, waitpid);
		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
#ifdef RDUMP
		while ((to = (host ? rmtopen(tape, 2) :
			pipeout ? 1 : open(tape, O_WRONLY|O_CREAT, 0666))) < 0)
#else RDUMP
		while ((to =
			pipeout ? 1 : open(tape, O_WRONLY|O_CREAT, 0666)) < 0)
#endif RDUMP
		    {
			msg("Cannot open output \"%s\".\n", tape);
			if (!query("Do you want to retry the open?"))
				dumpabort();
		}

		enslave();  /* Share open tape file descriptor with slaves */

		asize = 0;
		tapeno++;		/* current tape sequence */
		newtape++;		/* new tape signal */
		spcl.c_volume++;
		spcl.c_type = TS_TAPE;
		spclrec();
		if (tapeno > 1)
			msg("Tape %d begins with blocks from ino %d\n",
				tapeno, ino);
	}
}

dumpabort()
{
	if (master != 0 && master != getpid())
		kill(master, SIGTERM);	/* Signals master to call dumpabort */
	else {
		killall();
		msg("The ENTIRE dump is aborted.\n");
	}
	Exit(X_ABORT);
}

Exit(status)
{
#ifdef TDEBUG
	msg("pid = %d exits with status %d\n", getpid(), status);
#endif TDEBUG
	exit(status);
}

/*
 * could use pipe() for this if flock() worked on pipes
 */
lockfile(fd)
	int fd[2];
{
	char tmpname[20];

	strcpy(tmpname, "/tmp/dumplockXXXXXX");
	mktemp(tmpname);
	if ((fd[1] = creat(tmpname, 0400)) < 0) {
		msg("Could not create lockfile ");
		perror(tmpname);
		dumpabort();
	}
	if ((fd[0] = open(tmpname, 0)) < 0) {
		msg("Could not reopen lockfile ");
		perror(tmpname);
		dumpabort();
	}
	unlink(tmpname);
}

enslave()
{
	int first[2], prev[2], next[2], cmd[2];     /* file descriptors */
	register int i, j;

	master = getpid();
	signal(SIGTERM, dumpabort); /* Slave sends SIGTERM on dumpabort() */
	signal(SIGPIPE, sigpipe);
	signal(SIGUSR1, tperror);    /* Slave sends SIGUSR1 on tape errors */
	lockfile(first);
	for (i = 0; i < SLAVES; i++) {
		if (i == 0) {
			prev[0] = first[1];
			prev[1] = first[0];
		} else {
			prev[0] = next[0];
			prev[1] = next[1];
			flock(prev[1], LOCK_EX);
		}
		if (i < SLAVES - 1) {
			lockfile(next);
		} else {
			next[0] = first[0];
			next[1] = first[1];	    /* Last slave loops back */
		}
		if (pipe(cmd) < 0 || (slavepid[i] = fork()) < 0) {
			msg("too many slaves, %d (recompile smaller) ", i);
			perror("");
			dumpabort();
		}
		slavefd[i] = cmd[1];
		if (slavepid[i] == 0) { 	    /* Slave starts up here */
			for (j = 0; j <= i; j++)
				close(slavefd[j]);
			signal(SIGINT, SIG_IGN);    /* Master handles this */
			doslave(cmd[0], prev, next);
			Exit(X_FINOK);
		}
		close(cmd[0]);
		if (i > 0) {
			close(prev[0]);
			close(prev[1]);
		}
	}
	close(first[0]);
	close(first[1]);
	master = 0; rotor = 0;
}

killall()
{
	register int i;

	for (i = 0; i < SLAVES; i++)
		if (slavepid[i] > 0)
			kill(slavepid[i], SIGKILL);
}

/*
 * 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.
 */
doslave(cmd, prev, next)
	register int cmd, prev[2], next[2];
{
	register int nread, toggle = 0;
	int nwrite;

	close(fi);
	if ((fi = open(disk, 0)) < 0) { 	/* Need our own seek pointer */
		perror("  DUMP: slave couldn't reopen disk");
		dumpabort();
	}
	/*
	 * Get list of blocks to dump, read the blocks into tape buffer
	 */
	while ((nread = atomic(read, cmd, req, reqsiz)) == reqsiz) {
		register struct req *p = req;
		for (trecno = 0; trecno < NTREC; trecno += p->count, p += p->count) {
			if (p->dblk) {
				bread(p->dblk, tblock[trecno],
					p->count * DEV_BSIZE);
			} else {
				if (p->count != 1 || atomic(read, cmd,
				    tblock[trecno], DEV_BSIZE) != DEV_BSIZE) {
					msg("Master/slave protocol botched.\n");
					dumpabort();
				}
			}
		}
		flock(prev[toggle], LOCK_EX);	/* Wait our turn */

#ifdef RDUMP
		if ((nwrite = (host ? rmtwrite(tblock[0], writesize)
			: write(to, tblock[0], writesize))) != writesize) {
#else RDUMP
		if ((nwrite = write(to, tblock[0], writesize))
		    != writesize) {
#endif RDUMP
			if (nwrite == -1) 
				perror("write");
			else
				msg("short write: got %d instead of %d\n",
				    nwrite, writesize);
			kill(master, SIGUSR1);
			for (;;)
				sigpause(0L);
		}
		toggle ^= 1;
		flock(next[toggle], LOCK_UN);	/* Next slave's turn */
	}					/* Also jolts him awake */
	if (nread != 0) {
		perror("  DUMP: error reading command pipe");
		dumpabort();
	}
}

/*
 * 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).
 */
atomic(func, fd, buf, count)
	int (*func)(), fd, count;
	char *buf;
{
	int got, need = count;

	while ((got = (*func)(fd, buf, need)) > 0 && (need -= got) > 0)
		buf += got;
	return (got < 0 ? got : count - need);
}