[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;
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 (!cfg.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 (!cfg.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

    /*
     * Set the backspace character to be whichever of ^H and ^? is
     * specified by bksp_is_delete.
     */
    {
	struct termios attrs;
	tcgetattr(pty_master_fd, &attrs);
	attrs.c_cc[VERASE] = cfg.bksp_is_delete ? '\177' : '\010';
	tcsetattr(pty_master_fd, TCSANOW, &attrs);
    }

    /*
     * 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 {
	    char *shell = getenv("SHELL");
	    char *shellname;
	    if (cfg.login_shell) {
		char *p = strrchr(shell, '/');
		shellname = smalloc(2+strlen(shell));
		p = p ? p+1 : shell;
		sprintf(shellname, "-%s", p);
	    } else
		shellname = shell;
	    execl(getenv("SHELL"), shellname, 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;
    size.ws_xpixel = (unsigned short) cols * font_dimension(0);
    size.ws_ypixel = (unsigned short) rows * font_dimension(1);
    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	static int pty_stamped_utmp = 0;
a0e16eb1	59	static int pty_child_pid;
a0e16eb1	60	static sig_atomic_t pty_child_dead;
755a6d84	61	#ifndef OMIT_UTMP
	62	static struct utmp utmp_entry;
	63	#endif
6169c758	64	char **pty_argv;
054d8535	65
a0e16eb1	66	int pty_child_is_dead(void)
	67	{
	68	return pty_child_dead;
	69	}
	70
1709795f	71	static void pty_size(void);
1709795f	72
755a6d84	73	static void setup_utmp(char *ttyname)
	74	{
	75	#ifndef OMIT_UTMP
	76	#ifdef HAVE_LASTLOG
	77	struct lastlog lastlog_entry;
	78	FILE *lastlog;
	79	#endif
	80	struct passwd *pw;
f51dc031	81	char *location;
755a6d84	82	FILE *wtmp;
755a6d84	83
c8ee61b9	84	if (!cfg.stamp_utmp)
f51dc031	85	return;
f51dc031	86
755a6d84	87	pw = getpwuid(getuid());
f51dc031	88	location = get_x_display();
755a6d84	89	memset(&utmp_entry, 0, sizeof(utmp_entry));
	90	utmp_entry.ut_type = USER_PROCESS;
	91	utmp_entry.ut_pid = getpid();
	92	strncpy(utmp_entry.ut_line, ttyname+5, lenof(utmp_entry.ut_line));
	93	strncpy(utmp_entry.ut_id, ttyname+8, lenof(utmp_entry.ut_id));
	94	strncpy(utmp_entry.ut_user, pw->pw_name, lenof(utmp_entry.ut_user));
	95	strncpy(utmp_entry.ut_host, location, lenof(utmp_entry.ut_host));
	96	time(&utmp_entry.ut_time);
	97
	98	#if defined HAVE_PUTUTLINE
	99	utmpname(UTMP_FILE);
	100	setutent();
	101	pututline(&utmp_entry);
	102	endutent();
	103	#endif
	104
	105	if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
	106	fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
	107	fclose(wtmp);
	108	}
	109
	110	#ifdef HAVE_LASTLOG
	111	memset(&lastlog_entry, 0, sizeof(lastlog_entry));
	112	strncpy(lastlog_entry.ll_line, ttyname+5, lenof(lastlog_entry.ll_line));
	113	strncpy(lastlog_entry.ll_host, location, lenof(lastlog_entry.ll_host));
	114	time(&lastlog_entry.ll_time);
	115	if ((lastlog = fopen(LASTLOG_FILE, "r+")) != NULL) {
	116	fseek(lastlog, sizeof(lastlog_entry) * getuid(), SEEK_SET);
	117	fwrite(&lastlog_entry, 1, sizeof(lastlog_entry), lastlog);
	118	fclose(lastlog);
	119	}
	120	#endif
	121
f51dc031	122	pty_stamped_utmp = 1;
f51dc031	123
755a6d84	124	#endif
	125	}
	126
	127	static void cleanup_utmp(void)
	128	{
	129	#ifndef OMIT_UTMP
	130	FILE *wtmp;
	131
c8ee61b9	132	if (!cfg.stamp_utmp \|\| !pty_stamped_utmp)
f51dc031	133	return;
f51dc031	134
755a6d84	135	utmp_entry.ut_type = DEAD_PROCESS;
	136	memset(utmp_entry.ut_user, 0, lenof(utmp_entry.ut_user));
	137	time(&utmp_entry.ut_time);
	138
	139	if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
	140	fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
	141	fclose(wtmp);
	142	}
	143
	144	memset(utmp_entry.ut_line, 0, lenof(utmp_entry.ut_line));
	145	utmp_entry.ut_time = 0;
	146
	147	#if defined HAVE_PUTUTLINE
	148	utmpname(UTMP_FILE);
	149	setutent();
	150	pututline(&utmp_entry);
	151	endutent();
	152	#endif
	153
f51dc031	154	pty_stamped_utmp = 0; /* ensure we never double-cleanup */
755a6d84	155	#endif
	156	}
	157
a0e16eb1	158	static void sigchld_handler(int signum)
	159	{
	160	pid_t pid;
	161	int status;
	162	pid = waitpid(-1, &status, WNOHANG);
	163	if (pid == pty_child_pid && (WIFEXITED(status) \|\| WIFSIGNALED(status)))
	164	pty_child_dead = TRUE;
	165	}
	166
755a6d84	167	static void fatal_sig_handler(int signum)
	168	{
	169	signal(signum, SIG_DFL);
	170	cleanup_utmp();
	171	setuid(getuid());
	172	raise(signum);
	173	}
	174
1709795f	175	/*
	176	* Called to set up the pty.
	177	*
	178	* Returns an error message, or NULL on success.
	179	*
	180	* Also places the canonical host name into `realhost'. It must be
	181	* freed by the caller.
	182	*/
	183	static char pty_init(char host, int port, char **realhost, int nodelay)
	184	{
054d8535	185	int slavefd;
054d8535	186	char name[FILENAME_MAX];
d37c2d81	187	pid_t pid, pgrp;
054d8535	188
be4f86de	189	#ifdef BSD_PTYS
	190	{
	191	const char chars1[] = "pqrstuvwxyz";
	192	const char chars2[] = "0123456789abcdef";
	193	const char p1, p2;
	194	char master_name[20];
	195
	196	for (p1 = chars1; *p1; p1++)
	197	for (p2 = chars2; *p2; p2++) {
	198	sprintf(master_name, "/dev/pty%c%c", p1, p2);
	199	pty_master_fd = open(master_name, O_RDWR);
	200	if (pty_master_fd >= 0) {
	201	if (geteuid() == 0 \|\|
	202	access(master_name, R_OK \| W_OK) == 0)
	203	goto got_one;
	204	close(pty_master_fd);
	205	}
	206	}
	207
	208	/* If we get here, we couldn't get a tty at all. */
	209	fprintf(stderr, "pterm: unable to open a pseudo-terminal device\n");
	210	exit(1);
	211
	212	got_one:
	213	strcpy(name, master_name);
	214	name[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */
	215	}
	216	#else
054d8535	217	pty_master_fd = open("/dev/ptmx", O_RDWR);
	218
	219	if (pty_master_fd < 0) {
	220	perror("/dev/ptmx: open");
	221	exit(1);
	222	}
	223
	224	if (grantpt(pty_master_fd) < 0) {
	225	perror("grantpt");
	226	exit(1);
	227	}
	228
	229	if (unlockpt(pty_master_fd) < 0) {
	230	perror("unlockpt");
	231	exit(1);
	232	}
	233
	234	name[FILENAME_MAX-1] = '\0';
	235	strncpy(name, ptsname(pty_master_fd), FILENAME_MAX-1);
be4f86de	236	#endif
054d8535	237
054d8535	238	/*
39baeaa4	239	* Set the backspace character to be whichever of ^H and ^? is
	240	* specified by bksp_is_delete.
	241	*/
	242	{
	243	struct termios attrs;
	244	tcgetattr(pty_master_fd, &attrs);
	245	attrs.c_cc[VERASE] = cfg.bksp_is_delete ? '\177' : '\010';
	246	tcsetattr(pty_master_fd, TCSANOW, &attrs);
	247	}
	248
	249	/*
755a6d84	250	* Trap as many fatal signals as we can in the hope of having
	251	* the best chance to clean up utmp before termination.
	252	*/
	253	signal(SIGHUP, fatal_sig_handler);
	254	signal(SIGINT, fatal_sig_handler);
	255	signal(SIGQUIT, fatal_sig_handler);
	256	signal(SIGILL, fatal_sig_handler);
	257	signal(SIGABRT, fatal_sig_handler);
	258	signal(SIGFPE, fatal_sig_handler);
	259	signal(SIGPIPE, fatal_sig_handler);
	260	signal(SIGALRM, fatal_sig_handler);
	261	signal(SIGTERM, fatal_sig_handler);
	262	signal(SIGSEGV, fatal_sig_handler);
	263	signal(SIGUSR1, fatal_sig_handler);
	264	signal(SIGUSR2, fatal_sig_handler);
	265	#ifdef SIGBUS
	266	signal(SIGBUS, fatal_sig_handler);
	267	#endif
	268	#ifdef SIGPOLL
	269	signal(SIGPOLL, fatal_sig_handler);
	270	#endif
	271	#ifdef SIGPROF
	272	signal(SIGPROF, fatal_sig_handler);
	273	#endif
	274	#ifdef SIGSYS
	275	signal(SIGSYS, fatal_sig_handler);
	276	#endif
	277	#ifdef SIGTRAP
	278	signal(SIGTRAP, fatal_sig_handler);
	279	#endif
	280	#ifdef SIGVTALRM
	281	signal(SIGVTALRM, fatal_sig_handler);
	282	#endif
	283	#ifdef SIGXCPU
	284	signal(SIGXCPU, fatal_sig_handler);
	285	#endif
	286	#ifdef SIGXFSZ
	287	signal(SIGXFSZ, fatal_sig_handler);
	288	#endif
	289	#ifdef SIGIO
	290	signal(SIGIO, fatal_sig_handler);
	291	#endif
	292	/* Also clean up utmp on normal exit. */
	293	atexit(cleanup_utmp);
	294	setup_utmp(name);
	295
	296	/*
054d8535	297	* Fork and execute the command.
	298	*/
	299	pid = fork();
	300	if (pid < 0) {
	301	perror("fork");
88e6b9ca	302	exit(1);
054d8535	303	}
	304
	305	if (pid == 0) {
	306	int i;
	307	/*
	308	* We are the child.
	309	*/
d37c2d81	310
	311	slavefd = open(name, O_RDWR);
	312	if (slavefd < 0) {
	313	perror("slave pty: open");
	314	exit(1);
	315	}
	316
be4f86de	317	#ifdef BSD_PTYS
	318	/* We need to chown/chmod the /dev/ttyXX device. */
	319	{
	320	struct group *gp = getgrnam("tty");
	321	fchown(slavefd, getuid(), gp ? gp->gr_gid : -1);
	322	fchmod(slavefd, 0600);
	323	}
	324	#endif
	325
054d8535	326	close(pty_master_fd);
	327	close(0);
	328	close(1);
	329	close(2);
	330	fcntl(slavefd, F_SETFD, 0); /* don't close on exec */
	331	dup2(slavefd, 0);
	332	dup2(slavefd, 1);
	333	dup2(slavefd, 2);
	334	setsid();
d37c2d81	335	ioctl(slavefd, TIOCSCTTY, 1);
	336	pgrp = getpid();
	337	tcsetpgrp(slavefd, pgrp);
	338	setpgrp();
	339	close(open(name, O_WRONLY, 0));
054d8535	340	setpgrp();
be4f86de	341	/* In case we were setgid-utmp or setuid-root, drop privs. */
	342	setgid(getgid());
	343	setuid(getuid());
054d8535	344	/* Close everything _else_, for tidiness. */
	345	for (i = 3; i < 1024; i++)
	346	close(i);
fe9548aa	347	{
	348	char term_env_var[10 + sizeof(cfg.termtype)];
	349	sprintf(term_env_var, "TERM=%s", cfg.termtype);
	350	putenv(term_env_var);
	351	}
6169c758	352	if (pty_argv)
6169c758	353	execvp(pty_argv[0], pty_argv);
c8ee61b9	354	else {
	355	char *shell = getenv("SHELL");
	356	char *shellname;
	357	if (cfg.login_shell) {
	358	char *p = strrchr(shell, '/');
	359	shellname = smalloc(2+strlen(shell));
	360	p = p ? p+1 : shell;
	361	sprintf(shellname, "-%s", p);
	362	} else
	363	shellname = shell;
	364	execl(getenv("SHELL"), shellname, NULL);
	365	}
	366
054d8535	367	/*
	368	* If we're here, exec has gone badly foom.
	369	*/
	370	perror("exec");
	371	exit(127);
	372	} else {
	373	close(slavefd);
a0e16eb1	374	pty_child_pid = pid;
	375	pty_child_dead = FALSE;
	376	signal(SIGCHLD, sigchld_handler);
054d8535	377	}
054d8535	378
1709795f	379	return NULL;
	380	}
	381
	382	/*
	383	* Called to send data down the pty.
	384	*/
	385	static int pty_send(char *buf, int len)
	386	{
054d8535	387	while (len > 0) {
	388	int ret = write(pty_master_fd, buf, len);
	389	if (ret < 0) {
	390	perror("write pty master");
	391	exit(1);
	392	}
	393	buf += ret;
	394	len -= ret;
	395	}
1709795f	396	return 0;
	397	}
	398
	399	/*
	400	* Called to query the current socket sendability status.
	401	*/
	402	static int pty_sendbuffer(void)
	403	{
	404	return 0;
	405	}
	406
	407	/*
	408	* Called to set the size of the window
	409	*/
	410	static void pty_size(void)
	411	{
88e6b9ca	412	struct winsize size;
	413
	414	size.ws_row = (unsigned short)rows;
	415	size.ws_col = (unsigned short)cols;
e9aef757	416	size.ws_xpixel = (unsigned short) cols * font_dimension(0);
e9aef757	417	size.ws_ypixel = (unsigned short) rows * font_dimension(1);
88e6b9ca	418	ioctl(pty_master_fd, TIOCSWINSZ, (void *)&size);
1709795f	419	return;
	420	}
	421
	422	/*
	423	* Send special codes.
	424	*/
	425	static void pty_special(Telnet_Special code)
	426	{
	427	/* Do nothing! */
	428	return;
	429	}
	430
	431	static Socket pty_socket(void)
	432	{
	433	return NULL; /* shouldn't ever be needed */
	434	}
	435
	436	static int pty_sendok(void)
	437	{
	438	return 1;
	439	}
	440
	441	static void pty_unthrottle(int backlog)
	442	{
	443	/* do nothing */
	444	}
	445
	446	static int pty_ldisc(int option)
	447	{
	448	return 0; /* neither editing nor echoing */
	449	}
	450
	451	static int pty_exitcode(void)
	452	{
	453	/* Shouldn't ever be required */
	454	return 0;
	455	}
	456
	457	Backend pty_backend = {
	458	pty_init,
	459	pty_send,
	460	pty_sendbuffer,
	461	pty_size,
	462	pty_special,
	463	pty_socket,
	464	pty_exitcode,
	465	pty_sendok,
	466	pty_ldisc,
	467	pty_unthrottle,
	468	1
	469	};