path: root/dumper.c

#include "config.h"
#include "conf.h"
#include "err.h"
#include "lock.h"
#include "strutil.h"

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#ifdef NEED_LIBUTIL
#include <libutil.h>
#endif

#ifdef NEED_STRINGS
#include <strings.h>
#endif

RCSID("$Id: dumper.c,v 1.1.1.1 1999/02/02 23:29:39 shmit Exp $");

struct diskinfo {
	char vol[MAXPATHLEN];		/* Volume name. */
	int dumplevel;			/* Level of dump, if applicable. */
	ssize_t size;			/* How big dump is expected to be. */
	auth_t authtype;		/* Type of auth for dump. */
	struct diskinfo *next;
};
typedef struct diskinfo diskinfo_t;

struct hostinfo {
	char host[MAXHOSTNAMELEN];	/* Hostname. */
	int socket;			/* The socket for the dump. */
	int port;			/* Port on which to send dump. */
	int pin[2], pout[2], perr[2];	/* Connection to RSH pipe. */
	diskinfo_t *disks;		/* Disk information. */
	struct hostinfo *next;
};
typedef struct hostinfo hostinfo_t;

int taperpipe[2];
short exit_status = -1;

/*
 * If something terminates abnormally, this will be called.
 */
void
sig_pipe(int signo)
{
	log_err("SIGPIPE caught.\n");
	exit_status = -3;
}

/*
 * Clean up a child.
 */
void
sig_child(int signo)
{
	int status;

	if (wait(&status) == -1)
		log_err("Warning: couldn't clean up child.\n");

	exit_status = WEXITSTATUS(status);
}

/*
 * Tell the taper to write a file to tape.
 */
void
write_to_tape(const char *spooldir, const char *host, const char *filen)
{
	char buffer[MAXLINE];
	struct sigaction sa, osa;

	/*
	 * If SIGPIPE comes when we're trying to write to the taper
	 * descriptor, silently ignore it.
	 */
        sa.sa_flags = 0;
        sigemptyset(&sa.sa_mask);
        sa.sa_handler = SIG_IGN;
        sigaction(SIGPIPE, &sa, &osa);

	log_info("%s: telling taper to write `%s/%s:%s' to tape.\n",
		 host, spooldir, host, filen);
	sprintf(buffer, DISK_REQ "%s/%s:%s\n", spooldir, host, filen);

	write(taperpipe[1], buffer, strlen(buffer));

	/* Put the old handler back. */
        sigaction(SIGPIPE, &osa, NULL);
}

/*
 * Create a file on the holding which will contain the dump.
 */
inline int
open_stagefile(const char *spooldir, const char *host, const char *name)
{
	char filen[MAXPATHLEN];

	/* TODO: sanity check the name argument. */

	log_info("%s: dumping output to `%s/%s:%s'.\n",
		 host, spooldir, host, name);
	snprintf(filen, sizeof(filen), "%s/%s:%s", spooldir, host, name);
	return open(filen, O_WRONLY|O_CREAT|O_TRUNC, 0666);
}

/*
 * Clear out remaining data on a file descriptor.
 */
int
flush(const char *host, int infd, int outfd, ssize_t *total)
{
	char buffer[MAXLINE];
	ssize_t readb;

	log_info("%s: flushing remaining output.\n", host);

	if (fcntl(infd, F_SETFL, 0) == -1) {
		log_err("%s: couldn't set input to non-blocking: %s.\n",
			host, strerror(errno));
		return 0;
	}

READ:
	while ((readb = read(infd, buffer, sizeof(buffer))) > 0) {
		ssize_t wrote = 0;

		*total += readb;
		while (wrote < readb) {
			ssize_t n;

		WRITE:
			n = write(outfd, buffer, readb-wrote);
			if (n == -1) {
				if (errno == EINTR)
					goto WRITE;
				log_err("TODO: fix this message.\n");
				return 0;
			}
			wrote += n;
		}
	}
	if (readb == -1) {
		if (errno == EINTR || errno == EAGAIN)
			goto READ;
		log_err("%s: error occurred while flushing"
			" remaining output: %s.\n", host, strerror(errno));
		return 0;
	}

	return 1;
}

/*
 * Say `Hello' to the remote host and wait for a 'How are you'.
 */
int
do_handshake(int infd, int outfd, char *host)
{
	char buffer[MAXLINE];
	ssize_t readb;

read_handshake:
	readb = read(infd, buffer, sizeof(buffer));
	if (readb == -1) {
		if (errno == EINTR)
			goto read_handshake;
		log_err("Master: couldn't read handshake from %s: %s.\n",
			host, strerror(errno));
		return -1;
	}
	buffer[readb-1] = '\0';

	if (strncmp(buffer, INIT_REQ, sizeof(buffer))) {
		log_err("Master: Bad protocol from %s: handshake: %s.\n",
			host, buffer);
		return -1;
	}

	if (write(outfd, INIT_ACK "\n", sizeof(INIT_ACK)) == -1) {
		log_err("Master: couldn't send handshake ACK to %s: %s.\n",
			host, strerror(errno));
		return -1;
	}

	return 0;
}

/*
 * Handle error conditions on the remote host.
 */
int
do_error(int infd, const char *host)
{
	if (fcntl(infd, F_SETFL, 0) == -1) {
		log_err("%s: couldn't set fd to"
			" blocking mode.\n", host);
		return 0;
	}

	readerr(infd, host);
	return 1;
}

/*
 * Ask the remote host to send us a disk.
 */
int
do_newfile(diskinfo_t *disk, hostinfo_t *host, const char *spooldir,
	   int *infd, int *outfd)
{
	char buffer[MAXLINE], word[MAXLINE], filen[MAXPATHLEN];
	char *i = filen;
	ssize_t readb;

	switch (disk->authtype) {
	case NOAUTH:
		snprintf(buffer, sizeof(buffer),
			 "%s %s %s %s %d %s %s\n",
			  DUMP_SENDME, DISK_NAME, disk->vol,
			  DISK_LEVEL, disk->dumplevel,
			  DISK_AUTH, AUTH_NOAUTH);
		break;
	case RSH:
		snprintf(buffer, sizeof(buffer),
			 "%s %s %s %s %d %s %s\n",
			  DUMP_SENDME, DISK_NAME, disk->vol,
			  DISK_LEVEL, disk->dumplevel,
			  DISK_AUTH, AUTH_RSH);
		break;
	default:
		log_err("%s: unknown auth type for %s: %d.\n",
			host->host, disk->vol, disk->authtype);
		break;
	}

	if (write(host->pin[1], buffer, strlen(buffer)) == -1) {
		log_err("%s: couldn't send instructions: %s.\n",
			host->host, strerror(errno));
		return -1;
	}

READ:
	readb = read(host->pout[0], buffer, sizeof(buffer));
	if (readb == -1) {
		if (errno == EINTR)
			goto READ;

		log_err("%s: couldn't read ACK for disk `%s': %s.\n",
			host->host, disk->vol, strerror(errno));
		return -1;
	} else if (!readb) {
		log_err("%s: rsh client died while setting up connection.\n",
			host->host);
		return -1;
	}
	buffer[readb] = '\0';

	i = getword(buffer, word);
	if (!strncmp(word, DUMP_ERROR, sizeof(word))) {
		do_error(host->perr[0], host->host);
		return -1;
	} else if (strncmp(word, REQ_ACK, sizeof(word))) {
		log_err("%s: don't understand `%s'.\n", host->host, buffer);
		return -1;
	}

	i = filen;
	strncpy(filen, disk->vol, sizeof(filen));
	while ((i = index(i, '/')))
		*i = '_';

	*outfd = open_stagefile(spooldir, host->host, filen);
	if (*outfd == -1)
		return -1;

	switch (disk->authtype) {
	case NOAUTH: {
		struct hostent *he;
		struct sockaddr_in sa;

		*infd = socket(PF_INET, SOCK_STREAM, 0);
		if (*infd == -1) {
			log_err("%s: couldn't create socket: %s.\n",
				host->host, strerror(errno));
			return -1;
		}

		/* TODO: make sure we're not an IP address. */
		he = gethostbyname(host->host);
		if (!he) {
			log_err("%s: couldn't resolve hostname `%s'.\n",
				host->host, host->host);
			return -1;
		}
		sa.sin_family = AF_INET;
		sa.sin_port = htons(host->port);
		memcpy(&sa.sin_addr.s_addr, he->h_addr,
		       sizeof(sa.sin_addr.s_addr));

		if (connect(*infd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
			log_err("%s: couldn't connect: %s.\n",
				host->host, strerror(errno));
			return -1;
		}
	}; break;
	case RSH:
		log_err("%s: RSH auth not supported right now.\n", host->host);
		return -1;
		break;
	default:
		log_err("%s: don't understand AUTH type: %d.\n",
			host->host, disk->authtype);
		return -1;
	}

	return 0;
}

/*
 * Read a disk from a stream and spool it to the holding disk.
 */
int
read_backup(diskinfo_t *disk, hostinfo_t *host,
	    const char *spooldir, int timeout)
{
	char buffer[MAXLINE];
	fd_set readfds, exceptfds;
	ssize_t readb, total = 0;
	time_t start;
	struct timeval tv;
	int infd, outfd;
	int done = 0, error = 0;

	fcntl(host->pout[0], F_SETFL, 0);
	if (do_newfile(disk, host, spooldir, &infd, &outfd) == -1) {
		if (exit_status != -1)
			return -1;
		else
			return 0;
	}
	fcntl(host->pout[0], F_SETFL, O_NONBLOCK);

	start = time(NULL);
	while (exit_status == -1) {
		FD_ZERO(&readfds);
		FD_ZERO(&exceptfds);
		FD_SET(infd, &readfds);
		FD_SET(infd, &exceptfds);
		FD_SET(host->pout[0], &readfds);
		FD_SET(host->pout[0], &exceptfds);
		FD_SET(host->perr[0], &readfds);
		FD_SET(host->perr[0], &exceptfds);
		tv.tv_sec = timeout;
		tv.tv_usec = 0;

		if (select(FD_SETSIZE, &readfds, NULL, &exceptfds, &tv) == -1) {
			if (errno == EINTR)
				continue;
			log_err("%s: select failed: %s.\n",
				host->host, strerror(errno));
			return -1;
		}

		/* TODO: check exceptfds. */

		if (FD_ISSET(host->pout[0], &readfds)) {
			char word[MAXLINE];
			char *p;

		READSTDOUT:
			readb = read(host->pout[0], buffer, sizeof(buffer));
			if (readb == -1) {
				if (errno == EINTR)
					goto READSTDOUT;
				log_err("%s: read died with: %s.\n",
					host->host, strerror(errno));
				break;
			} else if (!readb) {
				log_err("%s: rsh client died.\n", host->host);
				break;
			}

			p = getword(buffer, word);
			if (!strncmp(word, DUMP_ERROR, sizeof(word))) {
				if (*p == '\n')
					p++;
				do_error(host->perr[0], host->host);
				error = 1;
				break;
			} else if (!strncmp(word, DUMP_DONE, sizeof(word))) {
				flush(host->host, infd, outfd, &total);
				log_info("%s: Wrote %ld bytes in %d seconds.\n",
					 host->host, total, time(NULL)-start);
				done = 1;
				break;
			} else {
				log_err("%s: No header on following output;"
					" assuming error:\n", host->host);
				do_error(host->pout[0], host->host);
				error = 1;
				break;
			}
		}

		if (FD_ISSET(host->perr[0], &readfds)) {
		READSTDERR:
			readb = read(host->perr[0], buffer, sizeof(buffer));
			if (readb == -1) {
				if (errno == EINTR)
					goto READSTDERR;
				log_err("%s: read of stderr died with: %s.\n",
					host->host, strerror(errno));
				break;
			} else if (!readb) {
				log_err("%s: rsh client died.\n", host->host);
			}

			readerr(host->perr[0], host->host);
		}

		if (FD_ISSET(infd, &readfds)) {
		READDATA:
			readb = read(infd, buffer, sizeof(buffer));
			if (readb == -1) {
				if (errno == EINTR)
					goto READDATA;
				log_err("%s: read died with: %s.\n",
					host->host, strerror(errno));
				break;
			} else if (!readb)
				break;

			write(outfd, buffer, readb);
			total += readb;
		}
	}

	/* If we haven't seen any control information, scan for it now. */
	if (!done && !error) {
		ssize_t readb;

		/* TODO: check stderr too. */
		fcntl(host->pout[0], F_SETFL, 0);
	READ:
		readb = read(host->pout[0], buffer, sizeof(buffer));
		if (readb == -1) {
			if (errno == EINTR)
				goto READ;

			log_err("%s: read returned -1: %s.\n",
				host->host, strerror(errno));
		} else if (readb) {
			char word[MAXLINE];
			char *p;

			p = getword(buffer, word);
			if (!strncmp(word, DUMP_ERROR, sizeof(word))) {
				if (*p == '\n')
					p++;
				do_error(host->perr[0], host->host);
				return -1;
			} else if (!strncmp(word, DUMP_DONE, sizeof(word))) {
				flush(host->host, infd, outfd, &total);
				log_info("%s: Wrote %ld bytes in %d seconds.\n",
					 host->host, total, time(NULL)-start);
				done = 1;
			} else {
				log_err("%s: No header on following output;"
					" assuming error:\n", host->host);
				do_error(host->pout[0], host->host);
				return -1;
			}
		}
	}

	if (done) {
		char filen[MAXLINE];
		char *i;

		strncpy(filen, disk->vol, sizeof(filen));

		i = filen;
		while ((i = index(i, '/')))
			*i = '_';

		write_to_tape(spooldir, host->host, filen);
		return 0;
	}

	if (error)
		return -1;

	/*
	 * Exit status is grabbed by the wait function in sig_child.
	 * If we've come this far, we haven't recieved the DONE command
	 * from run-dump, so try and get some information and log it.
	 */
	switch (exit_status) {
	case -1:
		log_err("%s: premature death of rsh client.\n", host->host);
		break;
	case -2:
		log_err("%s: connection timed out.\n", host->host);
		break;
	case -3:
		log_err("%s: SIGPIPE received: this shoudn't have happened.\n",
			host->host);
		break;
	default:
		log_err("%s: run-dump exit status: %d.\n",
			host->host, exit_status);
	}

	return -1;
}

/*
 * Open up a connection to a host and back it up.
 */
int
do_backup(hostinfo_t *host, const char *spooldir, long timeout)
{
	diskinfo_t *disk = host->disks;
	pid_t pid;
	int status;
	struct sigaction sa, opsa, ocsa;

	log_info("%s: starting backup.\n", host->host);

	/* Set up signal handlers. */
	sa.sa_flags = 0;
	sigemptyset(&sa.sa_mask);
	sa.sa_handler = sig_pipe;
	sigaction(SIGPIPE, &sa, &opsa);
	sa.sa_handler = sig_child;
	sigaction(SIGCHLD, &sa, &ocsa);

	/* Set up the RSH master pipe and save file descriptors. */
	if (pipe(host->pin) == -1 || pipe(host->pout) == -1 ||
	    pipe(host->perr) == -1) {
		log_err("Master: couldn't allocate pipes for %s: %s.\n",
			host, strerror(errno));
		return -1;
	}

	pid = fork();
	if (pid < 0){
		log_err("%s: Couldn't fork: %s.\n",
			host->host, strerror(errno));
		return -1;
	} else if (!pid) {
		close(host->pin[1]);
		close(host->pout[0]);
		close(host->perr[0]);
		if (dup2(host->pin[0], STDIN_FILENO) == -1 ||
		    dup2(host->pout[1], STDOUT_FILENO) == -1 ||
		    dup2(host->perr[1], STDERR_FILENO) == -1)
			exit(1);

		execlp(PATH_RSH, PATH_RSH, host, "run-dump", NULL);
		err("Couldn't exec run-dump: %s.\n", strerror(errno));
		exit(1);
	}
	close(host->pin[0]);
	close(host->pout[1]);
	close(host->perr[1]);

	if (do_handshake(host->pout[0], host->pin[1], host->host) == -1)
		return -1;

	if (host->port) {
		char buffer[MAXLINE], word[MAXLINE];
		char *p = buffer;
		ssize_t readb;

		snprintf(buffer, sizeof(buffer), "%s %d\n",
			 PORT_REQ, host->port);
		write(host->pin[1], buffer, strlen(buffer));

	READ:
		readb = read(host->pout[0], buffer, sizeof(buffer));
		if (readb == -1) {
			if (errno == EINTR)
				goto READ;
			log_err("%s: read died: %s.\n",
				host->host, strerror(errno));
			return -1;
		}

		p = getword(buffer, word);
		if (!strncmp(word, DUMP_ERROR, sizeof(word))) {
			do_error(host->perr[0], host->host);
			return -1;
		} else if (strncmp(word, REQ_ACK, sizeof(word))) {
			log_err("%s: couldn't negotiate port.\n",
				host->host);
			return -1;
		}
	}

	/* TODO: this should probably happen before the handshake. */
	if (fcntl(host->pout[0], F_SETFL, O_NONBLOCK) == -1 ||
	    fcntl(host->perr[0], F_SETFL, O_NONBLOCK) == -1) {
		log_err("%s: couldn't put pipes into non blocking mode: %s.\n",
			host->host, strerror(errno));
		return -1;
	}

	while (disk) {
		if (read_backup(disk, host, spooldir, timeout) == -1)
			break;
		disk = disk->next;
	}

	/* Put the old handlers back. */
	sigaction(SIGCHLD, &ocsa, NULL);
	sigaction(SIGPIPE, &opsa, NULL);

	if (!disk)
		/* TODO: check return value? */
		write(host->pin[1], DUMP_DONE "\n", sizeof(DUMP_DONE));

	/* Potentially there is stuff on the stderr stream, so grab it now. */
	do_error(host->perr[0], host->host);

	/* Potentially, the child is still alive. */
	(void)wait(&status);

	close(host->pin[1]); close(host->pout[0]); close(host->perr[0]);

	log_info("%s: finished backup.\n", host->host);

	if (disk)
		return -1;

	return 0;
}

/*
 * Parse buffer into fields appropriate for diskinfo.
 */
int
add_disk(char *buffer, hostinfo_t *host)
{
	char word[MAXLINE];
	diskinfo_t *disk;
	char *p = buffer;

	disk = malloc(sizeof(diskinfo_t));
	if (!disk) {
		log_err("Master: couldn't allocate %d bytes.\n",
			sizeof(diskinfo_t));
		return -1;
	}

	disk->vol[0] = '\0';
	disk->dumplevel = 0;
	disk->size = 0;
	disk->authtype = RSH;
	disk->next = host->disks;

	while ((p = getword(p, word))) {
		if (!strncmp(word, DISK_NAME, sizeof(word))) {
			p = getword(p, disk->vol);
		} else if (!strncmp(word, DISK_AUTH, sizeof(word))) {
			p = getword(p, word);
			if (!strncmp(word, AUTH_NOAUTH, sizeof(word)))
				disk->authtype = NOAUTH;
			else if (!strncmp(word, AUTH_RSH, sizeof(word)))
				disk->authtype = RSH;
			else {
				log_err("Master: recieved AUTH field I don't"
					" recognize from %s: %s.\n",
					host->host, word);
				write(host->pin[1], REQ_NACK "\n",
				      sizeof(REQ_NACK));
				free(disk);
				return -1;
			}
		} else if (!strncmp(word, DISK_SIZE, sizeof(word))) {
			p = getword(p, word);
		} else {
			log_err("Master: recieved DISK field I don't"
				" recognize from %s: %s.\n",
				host->host, word);
			write(host->pin[1], REQ_NACK "\n", sizeof(REQ_NACK));
			free(disk);
			return -1;
		}
	}

	write(host->pin[1], REQ_ACK "\n", sizeof(REQ_ACK));
	host->disks = disk;
	return 0;
}

/*
 * Get a list of disks to dump with estimates (if applicable), and
 * a port to use for unauthenticated backups.
 */
int
init_connection(hostinfo_t *host)
{
	char line[MAXLINE];
	ssize_t readb;
	int done = 0;

	if (do_handshake(host->pout[0], host->pin[1], host->host) == -1)
		return -1;

	for (;;) {
		char *p = line;
		char word[MAXLINE];

	READ:
		readb = read(host->pout[0], line, sizeof(line));
		if (readb == -1) {
			if (errno == EINTR)
				goto READ;
			log_err("Master: couldn't read from %s: %s.\n",
				host->host, strerror(errno));
			return -1;
		}
		if (readb == 0) {
			log_err("Master: connection to %s"
				" prematurely closed.\n", host->host);
			return -1;
		}

		line[readb] = '\0';
		p = getword(line, word);
		if (!strncmp(word, PORT_REQ, sizeof(word))) {
			p = getword(p, word);
			if (!p) {
				log_err("Master: recieved a PORT"
					" request without an"
					" argument.\n");
				return -1;
			}
			host->port = atoi(word);
			if (write(host->pin[1], REQ_ACK "\n",
			    sizeof(REQ_ACK)) == -1) {
				log_err("Master: couldn't ACK PORT"
					" request: %s.\n",
					strerror(errno));
				return -1;
			}
			continue;
		}

		if (!strncmp(word, DISK_REQ, sizeof(word))) {
			if (add_disk(p, host) == -1)
				break;
			continue;
		}

		if (!strncmp(word, DUMP_DONE, sizeof(word))) {
			done = 1;
			break;
		}

		if (!strncmp(word, DUMP_ERROR, sizeof(word))) {
			if (*p == '\n')
				p++;
			do_error(host->perr[0], host->host);
			break;
		}

		log_err("Master: bad protocol from %s: recieved"
			" command I don't understand: %s.\n",
			host->host, word);
		break;
	}

	if (!done) {
		log_err("Master: connection to %s prematurely terminated.\n",
			host->host);
		return -1;
	}

	return 0;
}

/*
 * Open a connection to a host, get an estimate, and close the connection.
 */
int
addhost(hostinfo_t **hosts, const char *host)
{
	hostinfo_t *curhost;
	pid_t pid;
	int status;
	struct sigaction sa, opsa, ocsa;

	log_info("Master: getting estimate for %s.\n", host);

	curhost = malloc(sizeof(hostinfo_t));
	if (!curhost) {
		log_err("Master: couldn't allocate %d bytes for %s.\n",
			sizeof(hostinfo_t), host);
		return -1;
	}

	strncpy(curhost->host, host, sizeof(curhost->host));
	curhost->port = 0; curhost->socket = 0; curhost->disks = NULL;

	if (pipe(curhost->pin) == -1 || pipe(curhost->pout) == -1 ||
	    pipe(curhost->perr) == -1) {
		log_err("Master: couldn't allocate pipes for %s: %s.\n",
			host, strerror(errno));
		free(curhost);
		return -1;
	}

	/* Set up signal handlers. */
	sa.sa_flags = 0;
	sigemptyset(&sa.sa_mask);
	sa.sa_handler = sig_pipe;
	sigaction(SIGPIPE, &sa, &opsa);
	sa.sa_handler = sig_child;
	sigaction(SIGCHLD, &sa, &ocsa);

	/* Now set up the RSH pipe and save file descriptors. */
	pid = fork();
	if (pid < 0){
		free(curhost);
		return -1;
	} else if (!pid) {
		close(curhost->pin[1]);
		close(curhost->pout[0]);
		close(curhost->perr[0]);
		if (dup2(curhost->pin[0], STDIN_FILENO) == -1 ||
		    dup2(curhost->pout[1], STDOUT_FILENO) == -1 ||
		    dup2(curhost->perr[1], STDERR_FILENO) == -1)
			exit(1);

		execlp(PATH_RSH, PATH_RSH, host, "run-estimate", NULL);
		err("Couldn't exec run-dump: %s.\n", strerror(errno));
		exit(1);
	}
	close(curhost->pin[0]);
	close(curhost->pout[1]);
	close(curhost->perr[1]);

	/* Figure out what the client wants dumped and how. */
	if (init_connection(curhost) == -1) {
		free(curhost);
		kill(pid, SIGHUP);
		return -1;
	}

	/* Close the RSH connection. */
	close(curhost->pin[1]);
	close(curhost->pout[0]);
	close(curhost->perr[0]);

	/* Put the old handlers back. */
	sigaction(SIGCHLD, &ocsa, NULL);
	sigaction(SIGPIPE, &opsa, NULL);

	/*
	 * Potentially, the child has died after clobbering the signal
	 * handler, so hang out here and wait for it.
	 */

	/* TODO: check out exist status. */
	(void)wait(&status);

	/* Finished cleanly, add to list. */
	curhost->next = *hosts;
	*hosts = curhost;

	return 0;
}

int
main(int argc, char *argv[])
{
	FILE *host_list;
	const config_t *option;
	hostinfo_t *hosts = NULL, *curhost;
	char *spooldir;
	char infofilen[MAXPATHLEN], errorfilen[MAXPATHLEN];
	char host[MAXHOSTNAMELEN];
	int i = 0, retries, status;
	pid_t taperpid, pid;
	long timeout;

	if (read_config(SERVER_CONFIG_FILE) == -1)
		return 1;

	/*
	 * TODO: if an error occurs causing abnormal termination, call the
	 * reporter anyway.
	 */

	option = findopt(LOGDIR);
	if (!option) {
		fprintf(stderr,
			"Warning: `" LOGDIR "' has not been set,"
			" using %s.\n", getcwd(NULL, MAXPATHLEN));
		strcpy(infofilen, "./");
		strcpy(errorfilen, "./");
	} else {
		strcpy(infofilen, option->strvalue);
		strcat(infofilen, "/");
		strcpy(errorfilen, option->strvalue);
		strcat(errorfilen, "/");
	}

	option = findopt(INFOLOG);
	if (!option) {
		fprintf(stderr,
			"Warning: `" INFOLOG "' has not been set,"
			" using stdout.\n");
		strcpy(infofilen, "-");
	} else
		strcat(infofilen, option->strvalue);

	option = findopt(ERRORLOG);
	if (!option) {
		fprintf(stderr,
			"Warning: `" ERRORLOG "' has not been set,"
			" using stderr.\n");
		strcpy(errorfilen, "-");
	} else
		strcat(errorfilen, option->strvalue);

	initlog(infofilen, errorfilen);

	option = findopt(HOSTLIST);
	if (!option) {
		log_err("Master: hostlist hasn't been specified.\n");
		return 1;
	}
	host_list = fopen(option->strvalue, "r");
	if (!host_list) {
		log_err("Master: couldn't open host list.\n");
		return 2;
	}

	option = findopt(SPOOLDIR);
	if (!option) {
		log_err("Master: spooldir hasn't been specified.\n");
		return 1;
	}
	spooldir = option->strvalue;

	option = findopt(TIMEOUT);
	if (!option) {
		log_err("Master: timeout hasn't been specified.\n");
		return 1;
	}
	timeout = option->numvalue;

	/* TODO: create lock here. */

	/* Initialize host information by contacting said host. */
	while (fgets(host, sizeof(host), host_list)) {
		host[strlen(host)-1] = '\0';

		if (addhost(&hosts, host) == -1)
			log_err("Master: couldn't initiate connection"
				" with %s.\n", host);
	}
	fclose(host_list);

	/*
	 * TODO: do backup scheduling here.
	 */

	/* Start up the taper. */
	if (pipe(taperpipe) == -1) {
		log_err("Master: couldn't create pipes for taper.\n");
		return 1;
	}

	taperpid = fork();
	if (taperpid == -1) {
		log_err("Master: couldn't fork for taper.\n");
		return 1;
	} else if (!taperpid) {
		close(taperpipe[1]);
		dup2(taperpipe[0], STDIN_FILENO);

		(void)execlp(LIBEXECDIR "/taper", "taper", NULL);
		log_err("Master: couldn't exec taper: %s.\n", strerror(errno));
		exit(1);
	}
	close(taperpipe[0]);

	/*
	 * Main backup loop, open up connections to each host and
	 * back them up.
	 */
	setproctitle("Master");
	curhost = hosts;
	while (curhost) {
		retries = 0;
	FORK:
		pid = fork(); i++;
		if (pid < 0) {
			i--;
			if (errno == EAGAIN) {
				if (++retries > MAXRETRIES) {
					log_err("Fatal: couldn't fork, "
						"retries exceeded.\n");
					break;
				}
				log_err("Master: couldn't fork, sleeping.\n");
				sleep(5);
				goto FORK;
			}
			log_err("Master: couldn't fork, dying.\n");
			break;
		} else if (!pid) {
			setproctitle("Running backup of %s", curhost->host);

			if (do_backup(curhost, spooldir, timeout)) {
				log_err("Master: error occurred while"
					" backing up %s.\n", curhost->host);
				exit(2);
			}
			exit(0);
		}
		curhost = curhost->next;
	}

	/* Now hang out and wait for everything to finish up. */
	while (i) {
		if (wait(&status) == taperpid) {
			log_err("Master: taper died!\n");
		} else
			i--;
	}

	log_info("Master: waiting for taper to finish.\n");

	/* Allow these things to fail silently when the taper is dead. */
	(void)write(taperpipe[1], DUMP_DONE "\n", sizeof(DUMP_DONE)+1);
	(void)waitpid(taperpid, &status, 0);

	/* Now fire off something to generate and send reports. */
	switch (vfork()) {
	case 0:
		(void)execlp(LIBEXECDIR "/report", "report", NULL);
		perror("Error: couldn't exec report generator");
		_exit(3);
	case -1:
		perror("Couldn't spawn report generator");
		return 1;
	}

	/* TODO: unlock everything. */

	return 0;
}