[u/mdw/putty] / unix / pty.c

#define _XOPEN_SOURCE
#define _XOPEN_SOURCE_EXTENDED
#include <features.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <termios.h>
#include <grp.h>
#include <utmp.h>
#include <pwd.h>
#include <time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ioctl.h>

#include "putty.h"

#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif

#ifndef UTMP_FILE
#define UTMP_FILE "/var/run/utmp"
#endif
#ifndef WTMP_FILE
#define WTMP_FILE "/var/log/wtmp"
#endif
#ifndef LASTLOG_FILE
#ifdef _PATH_LASTLOG
#define LASTLOG_FILE _PATH_LASTLOG
#else
#define LASTLOG_FILE "/var/log/lastlog"
#endif
#endif

/*
 * Set up a default for vaguely sane systems. The idea is that if
 * OMIT_UTMP is not defined, then at least one of the symbols which
 * enable particular forms of utmp processing should be, if only so
 * that a link error can warn you that you should have defined
 * OMIT_UTMP if you didn't want any. Currently HAVE_PUTUTLINE is
 * the only such symbol.
 */
#ifndef OMIT_UTMP
#if !defined HAVE_PUTUTLINE
#define HAVE_PUTUTLINE
#endif
#endif

int pty_master_fd;
int pty_stamp_utmp = 1;
static int pty_stamped_utmp = 0;
static int pty_child_pid;
static sig_atomic_t pty_child_dead;
#ifndef OMIT_UTMP
static struct utmp utmp_entry;
#endif
char **pty_argv;

int pty_child_is_dead(void)
{
    return pty_child_dead;
}

static void pty_size(void);

static void setup_utmp(char *ttyname)
{
#ifndef OMIT_UTMP
#ifdef HAVE_LASTLOG
    struct lastlog lastlog_entry;
    FILE *lastlog;
#endif
    struct passwd *pw;
    char *location;
    FILE *wtmp;

    if (!pty_stamp_utmp)
	return;

    pw = getpwuid(getuid());
    location = get_x_display();
    memset(&utmp_entry, 0, sizeof(utmp_entry));
    utmp_entry.ut_type = USER_PROCESS;
    utmp_entry.ut_pid = getpid();
    strncpy(utmp_entry.ut_line, ttyname+5, lenof(utmp_entry.ut_line));
    strncpy(utmp_entry.ut_id, ttyname+8, lenof(utmp_entry.ut_id));
    strncpy(utmp_entry.ut_user, pw->pw_name, lenof(utmp_entry.ut_user));
    strncpy(utmp_entry.ut_host, location, lenof(utmp_entry.ut_host));
    time(&utmp_entry.ut_time);

#if defined HAVE_PUTUTLINE
    utmpname(UTMP_FILE);
    setutent();
    pututline(&utmp_entry);
    endutent();
#endif

    if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
	fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
	fclose(wtmp);
    }

#ifdef HAVE_LASTLOG
    memset(&lastlog_entry, 0, sizeof(lastlog_entry));
    strncpy(lastlog_entry.ll_line, ttyname+5, lenof(lastlog_entry.ll_line));
    strncpy(lastlog_entry.ll_host, location, lenof(lastlog_entry.ll_host));
    time(&lastlog_entry.ll_time);
    if ((lastlog = fopen(LASTLOG_FILE, "r+")) != NULL) {
	fseek(lastlog, sizeof(lastlog_entry) * getuid(), SEEK_SET);
	fwrite(&lastlog_entry, 1, sizeof(lastlog_entry), lastlog);
	fclose(lastlog);
    }
#endif

    pty_stamped_utmp = 1;

#endif
}

static void cleanup_utmp(void)
{
#ifndef OMIT_UTMP
    FILE *wtmp;

    if (!pty_stamp_utmp || !pty_stamped_utmp)
	return;

    utmp_entry.ut_type = DEAD_PROCESS;
    memset(utmp_entry.ut_user, 0, lenof(utmp_entry.ut_user));
    time(&utmp_entry.ut_time);

    if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
	fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
	fclose(wtmp);
    }

    memset(utmp_entry.ut_line, 0, lenof(utmp_entry.ut_line));
    utmp_entry.ut_time = 0;

#if defined HAVE_PUTUTLINE
    utmpname(UTMP_FILE);
    setutent();
    pututline(&utmp_entry);
    endutent();
#endif

    pty_stamped_utmp = 0;	       /* ensure we never double-cleanup */
#endif
}

static void sigchld_handler(int signum)
{
    pid_t pid;
    int status;
    pid = waitpid(-1, &status, WNOHANG);
    if (pid == pty_child_pid && (WIFEXITED(status) || WIFSIGNALED(status)))
	pty_child_dead = TRUE;	
}

static void fatal_sig_handler(int signum)
{
    signal(signum, SIG_DFL);
    cleanup_utmp();
    setuid(getuid());
    raise(signum);
}

/*
 * Called to set up the pty.
 * 
 * Returns an error message, or NULL on success.
 *
 * Also places the canonical host name into `realhost'. It must be
 * freed by the caller.
 */
static char *pty_init(char *host, int port, char **realhost, int nodelay)
{
    int slavefd;
    char name[FILENAME_MAX];
    pid_t pid, pgrp;

#ifdef BSD_PTYS
    {
	const char chars1[] = "pqrstuvwxyz";
	const char chars2[] = "0123456789abcdef";
	const char *p1, *p2;
	char master_name[20];

	for (p1 = chars1; *p1; p1++)
	    for (p2 = chars2; *p2; p2++) {
		sprintf(master_name, "/dev/pty%c%c", *p1, *p2);
		pty_master_fd = open(master_name, O_RDWR);
		if (pty_master_fd >= 0) {
		    if (geteuid() == 0 ||
			access(master_name, R_OK | W_OK) == 0)
			goto got_one;
		    close(pty_master_fd);
		}
	    }

	/* If we get here, we couldn't get a tty at all. */
	fprintf(stderr, "pterm: unable to open a pseudo-terminal device\n");
	exit(1);

	got_one:
	strcpy(name, master_name);
	name[5] = 't';		       /* /dev/ptyXX -> /dev/ttyXX */
    }
#else
    pty_master_fd = open("/dev/ptmx", O_RDWR);

    if (pty_master_fd < 0) {
	perror("/dev/ptmx: open");
	exit(1);
    }

    if (grantpt(pty_master_fd) < 0) {
	perror("grantpt");
	exit(1);
    }
    
    if (unlockpt(pty_master_fd) < 0) {
	perror("unlockpt");
	exit(1);
    }

    name[FILENAME_MAX-1] = '\0';
    strncpy(name, ptsname(pty_master_fd), FILENAME_MAX-1);
#endif

    /*
     * Trap as many fatal signals as we can in the hope of having
     * the best chance to clean up utmp before termination.
     */
    signal(SIGHUP, fatal_sig_handler);
    signal(SIGINT, fatal_sig_handler);
    signal(SIGQUIT, fatal_sig_handler);
    signal(SIGILL, fatal_sig_handler);
    signal(SIGABRT, fatal_sig_handler);
    signal(SIGFPE, fatal_sig_handler);
    signal(SIGPIPE, fatal_sig_handler);
    signal(SIGALRM, fatal_sig_handler);
    signal(SIGTERM, fatal_sig_handler);
    signal(SIGSEGV, fatal_sig_handler);
    signal(SIGUSR1, fatal_sig_handler);
    signal(SIGUSR2, fatal_sig_handler);
#ifdef SIGBUS
    signal(SIGBUS, fatal_sig_handler);
#endif
#ifdef SIGPOLL
    signal(SIGPOLL, fatal_sig_handler);
#endif
#ifdef SIGPROF
    signal(SIGPROF, fatal_sig_handler);
#endif
#ifdef SIGSYS
    signal(SIGSYS, fatal_sig_handler);
#endif
#ifdef SIGTRAP
    signal(SIGTRAP, fatal_sig_handler);
#endif
#ifdef SIGVTALRM
    signal(SIGVTALRM, fatal_sig_handler);
#endif
#ifdef SIGXCPU
    signal(SIGXCPU, fatal_sig_handler);
#endif
#ifdef SIGXFSZ
    signal(SIGXFSZ, fatal_sig_handler);
#endif
#ifdef SIGIO
    signal(SIGIO, fatal_sig_handler);
#endif
    /* Also clean up utmp on normal exit. */
    atexit(cleanup_utmp);
    setup_utmp(name);

    /*
     * Fork and execute the command.
     */
    pid = fork();
    if (pid < 0) {
	perror("fork");
	exit(1);
    }

    if (pid == 0) {
	int i;
	/*
	 * We are the child.
	 */

	slavefd = open(name, O_RDWR);
	if (slavefd < 0) {
	    perror("slave pty: open");
	    exit(1);
	}

#ifdef BSD_PTYS
	/* We need to chown/chmod the /dev/ttyXX device. */
	{
	    struct group *gp = getgrnam("tty");
	    fchown(slavefd, getuid(), gp ? gp->gr_gid : -1);
	    fchmod(slavefd, 0600);
	}
#endif

	close(pty_master_fd);
	close(0);
	close(1);
	close(2);
	fcntl(slavefd, F_SETFD, 0);    /* don't close on exec */
	dup2(slavefd, 0);
	dup2(slavefd, 1);
	dup2(slavefd, 2);
	setsid();
	ioctl(slavefd, TIOCSCTTY, 1);
	pgrp = getpid();
	tcsetpgrp(slavefd, pgrp);
	setpgrp();
	close(open(name, O_WRONLY, 0));
	setpgrp();
	/* In case we were setgid-utmp or setuid-root, drop privs. */
	setgid(getgid());
	setuid(getuid());
	/* Close everything _else_, for tidiness. */
	for (i = 3; i < 1024; i++)
	    close(i);
	{
	    char term_env_var[10 + sizeof(cfg.termtype)];
	    sprintf(term_env_var, "TERM=%s", cfg.termtype);
	    putenv(term_env_var);
	}
	if (pty_argv)
	    execvp(pty_argv[0], pty_argv);
	else
	    execl(getenv("SHELL"), getenv("SHELL"), NULL);
	/*
	 * If we're here, exec has gone badly foom.
	 */
	perror("exec");
	exit(127);
    } else {
	close(slavefd);
	pty_child_pid = pid;
	pty_child_dead = FALSE;
	signal(SIGCHLD, sigchld_handler);
    }

    return NULL;
}

/*
 * Called to send data down the pty.
 */
static int pty_send(char *buf, int len)
{
    while (len > 0) {
	int ret = write(pty_master_fd, buf, len);
	if (ret < 0) {
	    perror("write pty master");
	    exit(1);
	}
	buf += ret;
	len -= ret;
    }
    return 0;
}

/*
 * Called to query the current socket sendability status.
 */
static int pty_sendbuffer(void)
{
    return 0;
}

/*
 * Called to set the size of the window
 */
static void pty_size(void)
{
    struct winsize size;

    size.ws_row = (unsigned short)rows;
    size.ws_col = (unsigned short)cols;
    ioctl(pty_master_fd, TIOCSWINSZ, (void *)&size);
    return;
}

/*
 * Send special codes.
 */
static void pty_special(Telnet_Special code)
{
    /* Do nothing! */
    return;
}

static Socket pty_socket(void)
{
    return NULL;		       /* shouldn't ever be needed */
}

static int pty_sendok(void)
{
    return 1;
}

static void pty_unthrottle(int backlog)
{
    /* do nothing */
}

static int pty_ldisc(int option)
{
    return 0;			       /* neither editing nor echoing */
}

static int pty_exitcode(void)
{
    /* Shouldn't ever be required */
    return 0;
}

Backend pty_backend = {
    pty_init,
    pty_send,
    pty_sendbuffer,
    pty_size,
    pty_special,
    pty_socket,
    pty_exitcode,
    pty_sendok,
    pty_ldisc,
    pty_unthrottle,
    1
};
Commit	Line	Data
054d8535	1	#define _XOPEN_SOURCE
88e6b9ca	2	#define _XOPEN_SOURCE_EXTENDED
054d8535	3	#include <features.h>
054d8535	4
1709795f	5	#include <stdio.h>
1709795f	6	#include <stdlib.h>
054d8535	7	#include <string.h>
054d8535	8	#include <unistd.h>
a0e16eb1	9	#include <signal.h>
054d8535	10	#include <fcntl.h>
88e6b9ca	11	#include <termios.h>
be4f86de	12	#include <grp.h>
755a6d84	13	#include <utmp.h>
	14	#include <pwd.h>
	15	#include <time.h>
a0e16eb1	16	#include <sys/types.h>
a0e16eb1	17	#include <sys/wait.h>
88e6b9ca	18	#include <sys/ioctl.h>
1709795f	19
	20	#include "putty.h"
	21
	22	#ifndef FALSE
	23	#define FALSE 0
	24	#endif
	25	#ifndef TRUE
	26	#define TRUE 1
	27	#endif
	28
755a6d84	29	#ifndef UTMP_FILE
	30	#define UTMP_FILE "/var/run/utmp"
	31	#endif
	32	#ifndef WTMP_FILE
	33	#define WTMP_FILE "/var/log/wtmp"
	34	#endif
	35	#ifndef LASTLOG_FILE
	36	#ifdef _PATH_LASTLOG
	37	#define LASTLOG_FILE _PATH_LASTLOG
	38	#else
	39	#define LASTLOG_FILE "/var/log/lastlog"
	40	#endif
	41	#endif
	42
f51dc031	43	/*
	44	* Set up a default for vaguely sane systems. The idea is that if
	45	* OMIT_UTMP is not defined, then at least one of the symbols which
	46	* enable particular forms of utmp processing should be, if only so
	47	* that a link error can warn you that you should have defined
	48	* OMIT_UTMP if you didn't want any. Currently HAVE_PUTUTLINE is
	49	* the only such symbol.
	50	*/
	51	#ifndef OMIT_UTMP
	52	#if !defined HAVE_PUTUTLINE
	53	#define HAVE_PUTUTLINE
	54	#endif
	55	#endif
	56
054d8535	57	int pty_master_fd;
f51dc031	58	int pty_stamp_utmp = 1;
f51dc031	59	static int pty_stamped_utmp = 0;
a0e16eb1	60	static int pty_child_pid;
a0e16eb1	61	static sig_atomic_t pty_child_dead;
755a6d84	62	#ifndef OMIT_UTMP
	63	static struct utmp utmp_entry;
	64	#endif
6169c758	65	char **pty_argv;
054d8535	66
a0e16eb1	67	int pty_child_is_dead(void)
	68	{
	69	return pty_child_dead;
	70	}
	71
1709795f	72	static void pty_size(void);
1709795f	73
755a6d84	74	static void setup_utmp(char *ttyname)
	75	{
	76	#ifndef OMIT_UTMP
	77	#ifdef HAVE_LASTLOG
	78	struct lastlog lastlog_entry;
	79	FILE *lastlog;
	80	#endif
	81	struct passwd *pw;
f51dc031	82	char *location;
755a6d84	83	FILE *wtmp;
755a6d84	84
f51dc031	85	if (!pty_stamp_utmp)
	86	return;
	87
755a6d84	88	pw = getpwuid(getuid());
f51dc031	89	location = get_x_display();
755a6d84	90	memset(&utmp_entry, 0, sizeof(utmp_entry));
	91	utmp_entry.ut_type = USER_PROCESS;
	92	utmp_entry.ut_pid = getpid();
	93	strncpy(utmp_entry.ut_line, ttyname+5, lenof(utmp_entry.ut_line));
	94	strncpy(utmp_entry.ut_id, ttyname+8, lenof(utmp_entry.ut_id));
	95	strncpy(utmp_entry.ut_user, pw->pw_name, lenof(utmp_entry.ut_user));
	96	strncpy(utmp_entry.ut_host, location, lenof(utmp_entry.ut_host));
	97	time(&utmp_entry.ut_time);
	98
	99	#if defined HAVE_PUTUTLINE
	100	utmpname(UTMP_FILE);
	101	setutent();
	102	pututline(&utmp_entry);
	103	endutent();
	104	#endif
	105
	106	if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
	107	fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
	108	fclose(wtmp);
	109	}
	110
	111	#ifdef HAVE_LASTLOG
	112	memset(&lastlog_entry, 0, sizeof(lastlog_entry));
	113	strncpy(lastlog_entry.ll_line, ttyname+5, lenof(lastlog_entry.ll_line));
	114	strncpy(lastlog_entry.ll_host, location, lenof(lastlog_entry.ll_host));
	115	time(&lastlog_entry.ll_time);
	116	if ((lastlog = fopen(LASTLOG_FILE, "r+")) != NULL) {
	117	fseek(lastlog, sizeof(lastlog_entry) * getuid(), SEEK_SET);
	118	fwrite(&lastlog_entry, 1, sizeof(lastlog_entry), lastlog);
	119	fclose(lastlog);
	120	}
	121	#endif
	122
f51dc031	123	pty_stamped_utmp = 1;
f51dc031	124
755a6d84	125	#endif
	126	}
	127
	128	static void cleanup_utmp(void)
	129	{
	130	#ifndef OMIT_UTMP
	131	FILE *wtmp;
	132
f51dc031	133	if (!pty_stamp_utmp \|\| !pty_stamped_utmp)
	134	return;
	135
755a6d84	136	utmp_entry.ut_type = DEAD_PROCESS;
	137	memset(utmp_entry.ut_user, 0, lenof(utmp_entry.ut_user));
	138	time(&utmp_entry.ut_time);
	139
	140	if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
	141	fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
	142	fclose(wtmp);
	143	}
	144
	145	memset(utmp_entry.ut_line, 0, lenof(utmp_entry.ut_line));
	146	utmp_entry.ut_time = 0;
	147
	148	#if defined HAVE_PUTUTLINE
	149	utmpname(UTMP_FILE);
	150	setutent();
	151	pututline(&utmp_entry);
	152	endutent();
	153	#endif
	154
f51dc031	155	pty_stamped_utmp = 0; /* ensure we never double-cleanup */
755a6d84	156	#endif
	157	}
	158
a0e16eb1	159	static void sigchld_handler(int signum)
	160	{
	161	pid_t pid;
	162	int status;
	163	pid = waitpid(-1, &status, WNOHANG);
	164	if (pid == pty_child_pid && (WIFEXITED(status) \|\| WIFSIGNALED(status)))
	165	pty_child_dead = TRUE;
	166	}
	167
755a6d84	168	static void fatal_sig_handler(int signum)
	169	{
	170	signal(signum, SIG_DFL);
	171	cleanup_utmp();
	172	setuid(getuid());
	173	raise(signum);
	174	}
	175
1709795f	176	/*
	177	* Called to set up the pty.
	178	*
	179	* Returns an error message, or NULL on success.
	180	*
	181	* Also places the canonical host name into `realhost'. It must be
	182	* freed by the caller.
	183	*/
	184	static char pty_init(char host, int port, char **realhost, int nodelay)
	185	{
054d8535	186	int slavefd;
054d8535	187	char name[FILENAME_MAX];
d37c2d81	188	pid_t pid, pgrp;
054d8535	189
be4f86de	190	#ifdef BSD_PTYS
	191	{
	192	const char chars1[] = "pqrstuvwxyz";
	193	const char chars2[] = "0123456789abcdef";
	194	const char p1, p2;
	195	char master_name[20];
	196
	197	for (p1 = chars1; *p1; p1++)
	198	for (p2 = chars2; *p2; p2++) {
	199	sprintf(master_name, "/dev/pty%c%c", p1, p2);
	200	pty_master_fd = open(master_name, O_RDWR);
	201	if (pty_master_fd >= 0) {
	202	if (geteuid() == 0 \|\|
	203	access(master_name, R_OK \| W_OK) == 0)
	204	goto got_one;
	205	close(pty_master_fd);
	206	}
	207	}
	208
	209	/* If we get here, we couldn't get a tty at all. */
	210	fprintf(stderr, "pterm: unable to open a pseudo-terminal device\n");
	211	exit(1);
	212
	213	got_one:
	214	strcpy(name, master_name);
	215	name[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */
	216	}
	217	#else
054d8535	218	pty_master_fd = open("/dev/ptmx", O_RDWR);
	219
	220	if (pty_master_fd < 0) {
	221	perror("/dev/ptmx: open");
	222	exit(1);
	223	}
	224
	225	if (grantpt(pty_master_fd) < 0) {
	226	perror("grantpt");
	227	exit(1);
	228	}
	229
	230	if (unlockpt(pty_master_fd) < 0) {
	231	perror("unlockpt");
	232	exit(1);
	233	}
	234
	235	name[FILENAME_MAX-1] = '\0';
	236	strncpy(name, ptsname(pty_master_fd), FILENAME_MAX-1);
be4f86de	237	#endif
054d8535	238
054d8535	239	/*
755a6d84	240	* Trap as many fatal signals as we can in the hope of having
	241	* the best chance to clean up utmp before termination.
	242	*/
	243	signal(SIGHUP, fatal_sig_handler);
	244	signal(SIGINT, fatal_sig_handler);
	245	signal(SIGQUIT, fatal_sig_handler);
	246	signal(SIGILL, fatal_sig_handler);
	247	signal(SIGABRT, fatal_sig_handler);
	248	signal(SIGFPE, fatal_sig_handler);
	249	signal(SIGPIPE, fatal_sig_handler);
	250	signal(SIGALRM, fatal_sig_handler);
	251	signal(SIGTERM, fatal_sig_handler);
	252	signal(SIGSEGV, fatal_sig_handler);
	253	signal(SIGUSR1, fatal_sig_handler);
	254	signal(SIGUSR2, fatal_sig_handler);
	255	#ifdef SIGBUS
	256	signal(SIGBUS, fatal_sig_handler);
	257	#endif
	258	#ifdef SIGPOLL
	259	signal(SIGPOLL, fatal_sig_handler);
	260	#endif
	261	#ifdef SIGPROF
	262	signal(SIGPROF, fatal_sig_handler);
	263	#endif
	264	#ifdef SIGSYS
	265	signal(SIGSYS, fatal_sig_handler);
	266	#endif
	267	#ifdef SIGTRAP
	268	signal(SIGTRAP, fatal_sig_handler);
	269	#endif
	270	#ifdef SIGVTALRM
	271	signal(SIGVTALRM, fatal_sig_handler);
	272	#endif
	273	#ifdef SIGXCPU
	274	signal(SIGXCPU, fatal_sig_handler);
	275	#endif
	276	#ifdef SIGXFSZ
	277	signal(SIGXFSZ, fatal_sig_handler);
	278	#endif
	279	#ifdef SIGIO
	280	signal(SIGIO, fatal_sig_handler);
	281	#endif
	282	/* Also clean up utmp on normal exit. */
	283	atexit(cleanup_utmp);
	284	setup_utmp(name);
	285
	286	/*
054d8535	287	* Fork and execute the command.
	288	*/
	289	pid = fork();
	290	if (pid < 0) {
	291	perror("fork");
88e6b9ca	292	exit(1);
054d8535	293	}
	294
	295	if (pid == 0) {
	296	int i;
	297	/*
	298	* We are the child.
	299	*/
d37c2d81	300
	301	slavefd = open(name, O_RDWR);
	302	if (slavefd < 0) {
	303	perror("slave pty: open");
	304	exit(1);
	305	}
	306
be4f86de	307	#ifdef BSD_PTYS
	308	/* We need to chown/chmod the /dev/ttyXX device. */
	309	{
	310	struct group *gp = getgrnam("tty");
	311	fchown(slavefd, getuid(), gp ? gp->gr_gid : -1);
	312	fchmod(slavefd, 0600);
	313	}
	314	#endif
	315
054d8535	316	close(pty_master_fd);
	317	close(0);
	318	close(1);
	319	close(2);
	320	fcntl(slavefd, F_SETFD, 0); /* don't close on exec */
	321	dup2(slavefd, 0);
	322	dup2(slavefd, 1);
	323	dup2(slavefd, 2);
	324	setsid();
d37c2d81	325	ioctl(slavefd, TIOCSCTTY, 1);
	326	pgrp = getpid();
	327	tcsetpgrp(slavefd, pgrp);
	328	setpgrp();
	329	close(open(name, O_WRONLY, 0));
054d8535	330	setpgrp();
be4f86de	331	/* In case we were setgid-utmp or setuid-root, drop privs. */
	332	setgid(getgid());
	333	setuid(getuid());
054d8535	334	/* Close everything _else_, for tidiness. */
	335	for (i = 3; i < 1024; i++)
	336	close(i);
fe9548aa	337	{
	338	char term_env_var[10 + sizeof(cfg.termtype)];
	339	sprintf(term_env_var, "TERM=%s", cfg.termtype);
	340	putenv(term_env_var);
	341	}
6169c758	342	if (pty_argv)
	343	execvp(pty_argv[0], pty_argv);
	344	else
	345	execl(getenv("SHELL"), getenv("SHELL"), NULL);
054d8535	346	/*
	347	* If we're here, exec has gone badly foom.
	348	*/
	349	perror("exec");
	350	exit(127);
	351	} else {
	352	close(slavefd);
a0e16eb1	353	pty_child_pid = pid;
	354	pty_child_dead = FALSE;
	355	signal(SIGCHLD, sigchld_handler);
054d8535	356	}
054d8535	357
1709795f	358	return NULL;
	359	}
	360
	361	/*
	362	* Called to send data down the pty.
	363	*/
	364	static int pty_send(char *buf, int len)
	365	{
054d8535	366	while (len > 0) {
	367	int ret = write(pty_master_fd, buf, len);
	368	if (ret < 0) {
	369	perror("write pty master");
	370	exit(1);
	371	}
	372	buf += ret;
	373	len -= ret;
	374	}
1709795f	375	return 0;
	376	}
	377
	378	/*
	379	* Called to query the current socket sendability status.
	380	*/
	381	static int pty_sendbuffer(void)
	382	{
	383	return 0;
	384	}
	385
	386	/*
	387	* Called to set the size of the window
	388	*/
	389	static void pty_size(void)
	390	{
88e6b9ca	391	struct winsize size;
	392
	393	size.ws_row = (unsigned short)rows;
	394	size.ws_col = (unsigned short)cols;
	395	ioctl(pty_master_fd, TIOCSWINSZ, (void *)&size);
1709795f	396	return;
	397	}
	398
	399	/*
	400	* Send special codes.
	401	*/
	402	static void pty_special(Telnet_Special code)
	403	{
	404	/* Do nothing! */
	405	return;
	406	}
	407
	408	static Socket pty_socket(void)
	409	{
	410	return NULL; /* shouldn't ever be needed */
	411	}
	412
	413	static int pty_sendok(void)
	414	{
	415	return 1;
	416	}
	417
	418	static void pty_unthrottle(int backlog)
	419	{
	420	/* do nothing */
	421	}
	422
	423	static int pty_ldisc(int option)
	424	{
	425	return 0; /* neither editing nor echoing */
	426	}
	427
	428	static int pty_exitcode(void)
	429	{
	430	/* Shouldn't ever be required */
	431	return 0;
	432	}
	433
	434	Backend pty_backend = {
	435	pty_init,
	436	pty_send,
	437	pty_sendbuffer,
	438	pty_size,
	439	pty_special,
	440	pty_socket,
	441	pty_exitcode,
	442	pty_sendok,
	443	pty_ldisc,
	444	pty_unthrottle,
	445	1
	446	};