system.c

早期freebsd实现

	return;
    }
    getstorage(where, length, 1);
    memcpy(local, (char *)(storage+((where-storage_location))), length);
    if (apitrace) {
	Dump('(', local, length);
    }
}

/*ARGSUSED*/
void
movetothem(es, di, local, length)
unsigned int
    es,
    di;
char
    *local;
int
    length;
{
    long where = SEG_OFF_BACK(es, di);

    if (length > sizeof storage) {
	fprintf(stderr, "Internal API error - movetothem() length too long.\n");
	fprintf(stderr, "(detected in file %s, line %d)\n", __FILE__, __LINE__);
	quit();
    } else if (length == 0) {
	return;
    }
    freestorage();
    memcpy((char *)storage, local, length);
    if (apitrace) {
	Dump(')', local, length);
    }
    storage_length = length;
    storage_location = where;
    storage_must_send = 1;
}


char *
access_api(location, length, copyin)
char *
    location;
int
    length,
    copyin;			/* Do we need to copy in initially? */
{
    if (storage_accessed) {
	fprintf(stderr, "Internal error - storage accessed twice\n");
	fprintf(stderr, "(Encountered in file %s, line %d.)\n",
				__FILE__, __LINE__);
	quit();
    } else if (length != 0) {
	freestorage();
	getstorage((long)location, length, copyin);
	storage_accessed = 1;
    }
    return (char *) storage;
}

/*ARGSUSED*/
void
unaccess_api(location, local, length, copyout)
char 	*location;
char	*local;
int	length;
int	copyout;
{
    if (storage_accessed == 0) {
	fprintf(stderr, "Internal error - unnecessary unaccess_api call.\n");
	fprintf(stderr, "(Encountered in file %s, line %d.)\n",
			__FILE__, __LINE__);
	quit();
    }
    storage_accessed = 0;
    storage_must_send = copyout;	/* if needs to go back */
}

/*
 * Accept a connection from an API client, aborting if the child dies.
 */

static int
doconnect()
{
    fd_set fdset;
    int i;

    sock = -1;
    FD_ZERO(&fdset);
    while (shell_active && (sock == -1)) {
	FD_SET(serversock, &fdset);
	if ((i = select(serversock+1, &fdset,
		    (fd_set *)0, (fd_set *)0, (struct timeval *)0)) < 0) {
	    if (errno = EINTR) {
		continue;
	    } else {
		perror("in select waiting for API connection");
		return -1;
	    }
	} else {
	    i = accept(serversock, (struct sockaddr *)0, (int *)0);
	    if (i == -1) {
		perror("accepting API connection");
		return -1;
	    }
	    sock = i;
	}
    }
    /* If the process has already exited, we may need to close */
    if ((shell_active == 0) && (sock != -1)) {
	extern void setcommandmode();

	(void) close(sock);
	sock = -1;
	setcommandmode();	/* In case child_died sneaked in */
    }
    return 0;
}

/*
 * shell_continue() actually runs the command, and looks for API
 * requests coming back in.
 *
 * We are called from the main loop in telnet.c.
 */

int
shell_continue()
{
    int i;

    switch (state) {
    case DEAD:
	pause();			/* Nothing to do */
	break;
    case UNCONNECTED:
	if (doconnect() == -1) {
	    kill_connection();
	    return -1;
	}
	/* At this point, it is possible that we've gone away */
	if (shell_active == 0) {
	    kill_connection();
	    return -1;
	}
	if (api_exch_init(sock, "server") == -1) {
	    return -1;
	}
	while (state == UNCONNECTED) {
	    if (api_exch_incommand(EXCH_CMD_ASSOCIATE) == -1) {
		kill_connection();
		return -1;
	    } else {
		switch (doassociate()) {
		case -1:
		    kill_connection();
		    return -1;
		case 0:
		    break;
		case 1:
		    state = CONNECTED;
		}
	    }
	}
	break;
    case CONNECTED:
	switch (i = api_exch_nextcommand()) {
	case EXCH_CMD_REQUEST:
	    if (api_exch_intype(EXCH_TYPE_REGS, sizeof inputRegs,
				    (char *)&inputRegs) == -1) {
		kill_connection();
	    } else if (api_exch_intype(EXCH_TYPE_SREGS, sizeof inputSregs,
				    (char *)&inputSregs) == -1) {
		kill_connection();
	    } else if (nextstore() == -1) {
		kill_connection();
	    } else {
		handle_api(&inputRegs, &inputSregs);
		freestorage();			/* Send any storage back */
		if (api_exch_outcommand(EXCH_CMD_REPLY) == -1) {
		    kill_connection();
		} else if (api_exch_outtype(EXCH_TYPE_REGS, sizeof inputRegs,
				    (char *)&inputRegs) == -1) {
		    kill_connection();
		} else if (api_exch_outtype(EXCH_TYPE_SREGS, sizeof inputSregs,
				    (char *)&inputSregs) == -1) {
		    kill_connection();
		}
		/* Done, and it all worked! */
	    }
	    break;
	case EXCH_CMD_DISASSOCIATE:
	    kill_connection();
	    break;
	default:
	    if (i != -1) {
		fprintf(stderr,
			"Looking for a REQUEST or DISASSOCIATE command\n");
		fprintf(stderr, "\treceived 0x%02x.\n", i);
	    }
	    kill_connection();
	    break;
	}
    }
    return shell_active;
}


static void
child_died(code)
{
    union wait status;
    register int pid;

    while ((pid = wait3((int *)&status, WNOHANG, (struct rusage *)0)) > 0) {
	if (pid == shell_pid) {
	    char inputbuffer[100];
	    extern void setconnmode();
	    extern void ConnectScreen();

	    shell_active = 0;
	    if (sock != -1) {
		(void) close(sock);
		sock = -1;
	    }
	    printf("[Hit return to continue]");
	    fflush(stdout);
	    (void) gets(inputbuffer);
	    setconnmode();
	    ConnectScreen();	/* Turn screen on (if need be) */
	    (void) close(serversock);
	    (void) unlink(keyname);
	}
    }
    signal(SIGCHLD, child_died);
}


/*
 * Called from telnet.c to fork a lower command.com.  We
 * use the spint... routines so that we can pick up
 * interrupts generated by application programs.
 */


int
shell(argc,argv)
int	argc;
char	*argv[];
{
    int length;
    struct sockaddr_in server;
    char sockNAME[100];
    static char **whereAPI = 0;
    int fd;
    struct timeval tv;
    long ikey;
    extern long random();
    extern char *mktemp();
    extern char *strcpy();

    /* First, create verification file. */
    do {
	keyname = mktemp(strdup("/tmp/apiXXXXXX"));
	fd = open(keyname, O_RDWR|O_CREAT|O_EXCL, IREAD|IWRITE);
    } while ((fd == -1) && (errno == EEXIST));

    if (fd == -1) {
	perror("open");
	return 0;
    }

    /* Now, get seed for random */

    if (gettimeofday(&tv, (struct timezone *)0) == -1) {
	perror("gettimeofday");
	return 0;
    }
    srandom(tv.tv_usec);		/* seed random number generator */
    do {
	ikey = random();
    } while (ikey == 0);
    sprintf(key, "%lu\n", (unsigned long) ikey);
    if (write(fd, key, strlen(key)) != strlen(key)) {
	perror("write");
	return 0;
    }
    key[strlen(key)-1] = 0;		/* Get rid of newline */

    if (close(fd) == -1) {
	perror("close");
	return 0;
    }

    /* Next, create the socket which will be connected to */
    serversock = socket(AF_INET, SOCK_STREAM, 0);
    if (serversock < 0) {
	perror("opening API socket");
	return 0;
    }
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;
    server.sin_port = 0;
    if (bind(serversock, (struct sockaddr *)&server, sizeof server) < 0) {
	perror("binding API socket");
	return 0;
    }
    length = sizeof server;
    if (getsockname(serversock, (struct sockaddr *)&server, &length) < 0) {
	perror("getting API socket name");
	(void) close(serversock);
    }
    listen(serversock, 1);
    /* Get name to advertise in address list */
    strcpy(sockNAME, "API3270=");
    gethostname(sockNAME+strlen(sockNAME), sizeof sockNAME-strlen(sockNAME));
    if (strlen(sockNAME) > (sizeof sockNAME-(10+strlen(keyname)))) {
	fprintf(stderr, "Local hostname too large; using 'localhost'.\n");
	strcpy(sockNAME, "localhost");
    }
    sprintf(sockNAME+strlen(sockNAME), ":%u", ntohs(server.sin_port));
    sprintf(sockNAME+strlen(sockNAME), ":%s", keyname);

    if (whereAPI == 0) {
	char **ptr, **nextenv;
	extern char **environ;

	ptr = environ;
	nextenv = ourENVlist;
	while (*ptr) {
	    if (nextenv >= &ourENVlist[highestof(ourENVlist)-1]) {
		fprintf(stderr, "Too many environmental variables\n");
		break;
	    }
	    *nextenv++ = *ptr++;
	}
	whereAPI = nextenv++;
	*nextenv++ = 0;
	environ = ourENVlist;		/* New environment */
    }
    *whereAPI = sockNAME;

    child_died();			/* Start up signal handler */
    shell_active = 1;			/* We are running down below */
    if (shell_pid = vfork()) {
	if (shell_pid == -1) {
	    perror("vfork");
	    (void) close(serversock);
	} else {
	    state = UNCONNECTED;
	}
    } else {				/* New process */
	register int i;

	for (i = 3; i < 30; i++) {
	    (void) close(i);
	}
	if (argc == 1) {		/* Just get a shell */
	    char *cmdname;
	    extern char *getenv();

	    cmdname = getenv("SHELL");
	    execlp(cmdname, cmdname, 0);
	    perror("Exec'ing new shell...\n");
	    exit(1);
	} else {
	    execvp(argv[1], &argv[1]);
	    perror("Exec'ing command.\n");
	    exit(1);
	}
	/*NOTREACHED*/
    }
    return shell_active;		/* Go back to main loop */
}