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

/*
 * Pseudo-tty backend for pterm.
 * 
 * Unlike the other backends, data for this one is not neatly
 * encapsulated into a data structure, because it wouldn't make
 * sense to do so - the utmp stuff has to be done before a backend
 * is initialised, and starting a second pterm from the same
 * process would therefore be infeasible because privileges would
 * already have been dropped. Hence, I haven't bothered to keep the
 * data dynamically allocated: instead, the backend handle is just
 * a null pointer and ignored everywhere.
 */

#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 <errno.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 void *pty_frontend;
static char pty_name[FILENAME_MAX];
static int pty_stamped_utmp = 0;
static int pty_child_pid;
static int pty_utmp_helper_pid, pty_utmp_helper_pipe;
static int pty_term_width, pty_term_height;
static volatile sig_atomic_t pty_child_dead;
static volatile int pty_exit_code;
#ifndef OMIT_UTMP
static struct utmp utmp_entry;
#endif
char **pty_argv;

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

    pw = getpwuid(getuid());
    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_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)
{
    int save_errno = errno;
    pid_t pid;
    int status;

    do {
	pid = waitpid(-1, &status, WNOHANG);
	if (pid == pty_child_pid && (WIFEXITED(status) || WIFSIGNALED(status))) {
	    pty_exit_code = status;
	    pty_child_dead = TRUE;
	}
    } while(pid > 0);
    errno = save_errno;
}

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

static void pty_open_master(void)
{
#ifdef BSD_PTYS
    const char chars1[] = "pqrstuvwxyz";
    const char chars2[] = "0123456789abcdef";
    const char *p1, *p2;
    char master_name[20];
    struct group *gp;

    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(pty_name, master_name);
    pty_name[5] = 't';		       /* /dev/ptyXX -> /dev/ttyXX */

    /* We need to chown/chmod the /dev/ttyXX device. */
    gp = getgrnam("tty");
    chown(pty_name, getuid(), gp ? gp->gr_gid : -1);
    chmod(pty_name, 0600);
#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);
    }

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

/*
 * Pre-initialisation. This is here to get around the fact that GTK
 * doesn't like being run in setuid/setgid programs (probably
 * sensibly). So before we initialise GTK - and therefore before we
 * even process the command line - we check to see if we're running
 * set[ug]id. If so, we open our pty master _now_, chown it as
 * necessary, and drop privileges. We can always close it again
 * later. If we're potentially going to be doing utmp as well, we
 * also fork off a utmp helper process and communicate with it by
 * means of a pipe; the utmp helper will keep privileges in order
 * to clean up utmp when we exit (i.e. when its end of our pipe
 * closes).
 */
void pty_pre_init(void)
{
    pid_t pid;
    int pipefd[2];

    /* set the child signal handler straight away; it needs to be set
     * before we ever fork. */
    putty_signal(SIGCHLD, sigchld_handler);
    pty_master_fd = -1;

    if (geteuid() != getuid() || getegid() != getgid()) {
	pty_open_master();
    }

#ifndef OMIT_UTMP
    /*
     * Fork off the utmp helper.
     */
    if (pipe(pipefd) < 0) {
	perror("pterm: pipe");
	exit(1);
    }
    pid = fork();
    if (pid < 0) {
	perror("pterm: fork");
	exit(1);
    } else if (pid == 0) {
	char display[128], buffer[128];
	int dlen, ret;

	close(pipefd[1]);
	/*
	 * Now sit here until we receive a display name from the
	 * other end of the pipe, and then stamp utmp. Unstamp utmp
	 * again, and exit, when the pipe closes.
	 */

	dlen = 0;
	while (1) {
	    
	    ret = read(pipefd[0], buffer, lenof(buffer));
	    if (ret <= 0) {
		cleanup_utmp();
		_exit(0);
	    } else if (!pty_stamped_utmp) {
		if (dlen < lenof(display))
		    memcpy(display+dlen, buffer,
			   min(ret, lenof(display)-dlen));
		if (buffer[ret-1] == '\0') {
		    /*
		     * Now we have a display name. NUL-terminate
		     * it, and stamp utmp.
		     */
		    display[lenof(display)-1] = '\0';
		    /*
		     * Trap as many fatal signals as we can in the
		     * hope of having the best possible chance to
		     * clean up utmp before termination. We are
		     * unfortunately unprotected against SIGKILL,
		     * but that's life.
		     */
		    putty_signal(SIGHUP, fatal_sig_handler);
		    putty_signal(SIGINT, fatal_sig_handler);
		    putty_signal(SIGQUIT, fatal_sig_handler);
		    putty_signal(SIGILL, fatal_sig_handler);
		    putty_signal(SIGABRT, fatal_sig_handler);
		    putty_signal(SIGFPE, fatal_sig_handler);
		    putty_signal(SIGPIPE, fatal_sig_handler);
		    putty_signal(SIGALRM, fatal_sig_handler);
		    putty_signal(SIGTERM, fatal_sig_handler);
		    putty_signal(SIGSEGV, fatal_sig_handler);
		    putty_signal(SIGUSR1, fatal_sig_handler);
		    putty_signal(SIGUSR2, fatal_sig_handler);
#ifdef SIGBUS
		    putty_signal(SIGBUS, fatal_sig_handler);
#endif
#ifdef SIGPOLL
		    putty_signal(SIGPOLL, fatal_sig_handler);
#endif
#ifdef SIGPROF
		    putty_signal(SIGPROF, fatal_sig_handler);
#endif
#ifdef SIGSYS
		    putty_signal(SIGSYS, fatal_sig_handler);
#endif
#ifdef SIGTRAP
		    putty_signal(SIGTRAP, fatal_sig_handler);
#endif
#ifdef SIGVTALRM
		    putty_signal(SIGVTALRM, fatal_sig_handler);
#endif
#ifdef SIGXCPU
		    putty_signal(SIGXCPU, fatal_sig_handler);
#endif
#ifdef SIGXFSZ
		    putty_signal(SIGXFSZ, fatal_sig_handler);
#endif
#ifdef SIGIO
		    putty_signal(SIGIO, fatal_sig_handler);
#endif
		    setup_utmp(pty_name, display);
		}
	    }
	}
    } else {
	close(pipefd[0]);
	pty_utmp_helper_pid = pid;
	pty_utmp_helper_pipe = pipefd[1];
    }
#endif

    /* Drop privs. */
    {
	int gid = getgid(), uid = getuid();
#ifndef HAVE_NO_SETRESUID
	int setresgid(gid_t, gid_t, gid_t);
	int setresuid(uid_t, uid_t, uid_t);
	setresgid(gid, gid, gid);
	setresuid(uid, uid, uid);
#else
	setgid(getgid());
	setuid(getuid());
#endif
    }
}

/*
 * 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(void *frontend, void **backend_handle, Config *cfg,
		      char *host, int port, char **realhost, int nodelay)
{
    int slavefd;
    pid_t pid, pgrp;
    long windowid;

    pty_frontend = frontend;
    *backend_handle = NULL;	       /* we can't sensibly use this, sadly */

    pty_term_width = cfg->width;
    pty_term_height = cfg->height;

    if (pty_master_fd < 0)
	pty_open_master();

    /*
     * 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);
    }

    /*
     * Stamp utmp (that is, tell the utmp helper process to do so),
     * or not.
     */
    if (!cfg->stamp_utmp)
	close(pty_utmp_helper_pipe);   /* just let the child process die */
    else {
	char *location = get_x_display(pty_frontend);
	int len = strlen(location)+1, pos = 0;   /* +1 to include NUL */
	while (pos < len) {
	    int ret = write(pty_utmp_helper_pipe, location+pos, len - pos);
	    if (ret < 0) {
		perror("pterm: writing to utmp helper process");
		close(pty_utmp_helper_pipe);   /* arrgh, just give up */
		break;
	    }
	    pos += ret;
	}
    }

    windowid = get_windowid(pty_frontend);

    /*
     * 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(pty_name, O_RDWR);
	if (slavefd < 0) {
	    perror("slave pty: open");
	    _exit(1);
	}

	close(pty_master_fd);
	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(pty_name, O_WRONLY, 0));
	setpgrp();
	/* 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);
	}
	{
	    char windowid_env_var[40];
	    sprintf(windowid_env_var, "WINDOWID=%ld", windowid);
	    putenv(windowid_env_var);
	}
	/*
	 * SIGINT and SIGQUIT may have been set to ignored by our
	 * parent, particularly by things like sh -c 'pterm &' and
	 * some window managers. Reverse this for our child process.
	 */
	putty_signal(SIGINT, SIG_DFL);
	putty_signal(SIGQUIT, SIG_DFL);
	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 = snewn(2+strlen(shell), char);
		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 {
	pty_child_pid = pid;
	pty_child_dead = FALSE;
    }      

    return NULL;
}

/*
 * Stub routine (we don't have any need to reconfigure this backend).
 */
static void pty_reconfig(void *handle, Config *cfg)
{
}

/*
 * Stub routine (never called in pterm
 */
static void pty_free(void *handle)
{
}


/*
 * Called to send data down the pty.
 */
static int pty_send(void *handle, char *buf, int len)
{
    if (pty_master_fd < 0)
	return 0;		       /* ignore all writes if fd closed */

    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;
}

void pty_close(void)
{
    if (pty_master_fd >= 0) {
	close(pty_master_fd);
	pty_master_fd = -1;
    }
    close(pty_utmp_helper_pipe);       /* this causes utmp to be cleaned up */
}

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

/*
 * Called to set the size of the window
 */
static void pty_size(void *handle, int width, int height)
{
    struct winsize size;

    pty_term_width = width;
    pty_term_height = height;

    size.ws_row = (unsigned short)pty_term_height;
    size.ws_col = (unsigned short)pty_term_width;
    size.ws_xpixel = (unsigned short) pty_term_width *
	font_dimension(pty_frontend, 0);
    size.ws_ypixel = (unsigned short) pty_term_height *
	font_dimension(pty_frontend, 1);
    ioctl(pty_master_fd, TIOCSWINSZ, (void *)&size);
    return;
}

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

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

static int pty_sendok(void *handle)
{
    return 1;
}

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

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

static void pty_provide_ldisc(void *handle, void *ldisc)
{
    /* This is a stub. */
}

static void pty_provide_logctx(void *handle, void *logctx)
{
    /* This is a stub. */
}

static int pty_exitcode(void *handle)
{
    if (!pty_child_dead)
	return -1;		       /* not dead yet */
    else
	return pty_exit_code;
}

Backend pty_backend = {
    pty_init,
    pty_free,
    pty_reconfig,
    pty_send,
    pty_sendbuffer,
    pty_size,
    pty_special,
    pty_socket,
    pty_exitcode,
    pty_sendok,
    pty_ldisc,
    pty_provide_ldisc,
    pty_provide_logctx,
    pty_unthrottle,
    1
};
Commit	Line	Data
28d00fe4	1	/*
	2	* Pseudo-tty backend for pterm.
	3	*
	4	* Unlike the other backends, data for this one is not neatly
	5	* encapsulated into a data structure, because it wouldn't make
	6	* sense to do so - the utmp stuff has to be done before a backend
	7	* is initialised, and starting a second pterm from the same
	8	* process would therefore be infeasible because privileges would
	9	* already have been dropped. Hence, I haven't bothered to keep the
	10	* data dynamically allocated: instead, the backend handle is just
	11	* a null pointer and ignored everywhere.
	12	*/
	13
054d8535	14	#define _XOPEN_SOURCE
88e6b9ca	15	#define _XOPEN_SOURCE_EXTENDED
054d8535	16	#include <features.h>
054d8535	17
1709795f	18	#include <stdio.h>
1709795f	19	#include <stdlib.h>
054d8535	20	#include <string.h>
054d8535	21	#include <unistd.h>
a0e16eb1	22	#include <signal.h>
054d8535	23	#include <fcntl.h>
88e6b9ca	24	#include <termios.h>
be4f86de	25	#include <grp.h>
755a6d84	26	#include <utmp.h>
	27	#include <pwd.h>
	28	#include <time.h>
a0e16eb1	29	#include <sys/types.h>
a0e16eb1	30	#include <sys/wait.h>
88e6b9ca	31	#include <sys/ioctl.h>
0f33f9d1	32	#include <errno.h>
1709795f	33
	34	#include "putty.h"
	35
	36	#ifndef FALSE
	37	#define FALSE 0
	38	#endif
	39	#ifndef TRUE
	40	#define TRUE 1
	41	#endif
	42
755a6d84	43	#ifndef UTMP_FILE
	44	#define UTMP_FILE "/var/run/utmp"
	45	#endif
	46	#ifndef WTMP_FILE
	47	#define WTMP_FILE "/var/log/wtmp"
	48	#endif
	49	#ifndef LASTLOG_FILE
	50	#ifdef _PATH_LASTLOG
	51	#define LASTLOG_FILE _PATH_LASTLOG
	52	#else
	53	#define LASTLOG_FILE "/var/log/lastlog"
	54	#endif
	55	#endif
	56
f51dc031	57	/*
	58	* Set up a default for vaguely sane systems. The idea is that if
	59	* OMIT_UTMP is not defined, then at least one of the symbols which
	60	* enable particular forms of utmp processing should be, if only so
	61	* that a link error can warn you that you should have defined
	62	* OMIT_UTMP if you didn't want any. Currently HAVE_PUTUTLINE is
	63	* the only such symbol.
	64	*/
	65	#ifndef OMIT_UTMP
	66	#if !defined HAVE_PUTUTLINE
	67	#define HAVE_PUTUTLINE
	68	#endif
	69	#endif
	70
054d8535	71	int pty_master_fd;
a8327734	72	static void *pty_frontend;
95c47834	73	static char pty_name[FILENAME_MAX];
f51dc031	74	static int pty_stamped_utmp = 0;
a0e16eb1	75	static int pty_child_pid;
95c47834	76	static int pty_utmp_helper_pid, pty_utmp_helper_pipe;
f278d6f8	77	static int pty_term_width, pty_term_height;
0f33f9d1	78	static volatile sig_atomic_t pty_child_dead;
0f33f9d1	79	static volatile int pty_exit_code;
755a6d84	80	#ifndef OMIT_UTMP
	81	static struct utmp utmp_entry;
	82	#endif
6169c758	83	char **pty_argv;
054d8535	84
95c47834	85	static void setup_utmp(char ttyname, char location)
755a6d84	86	{
	87	#ifndef OMIT_UTMP
	88	#ifdef HAVE_LASTLOG
	89	struct lastlog lastlog_entry;
	90	FILE *lastlog;
	91	#endif
	92	struct passwd *pw;
755a6d84	93	FILE *wtmp;
	94
	95	pw = getpwuid(getuid());
	96	memset(&utmp_entry, 0, sizeof(utmp_entry));
	97	utmp_entry.ut_type = USER_PROCESS;
	98	utmp_entry.ut_pid = getpid();
	99	strncpy(utmp_entry.ut_line, ttyname+5, lenof(utmp_entry.ut_line));
	100	strncpy(utmp_entry.ut_id, ttyname+8, lenof(utmp_entry.ut_id));
	101	strncpy(utmp_entry.ut_user, pw->pw_name, lenof(utmp_entry.ut_user));
	102	strncpy(utmp_entry.ut_host, location, lenof(utmp_entry.ut_host));
	103	time(&utmp_entry.ut_time);
	104
	105	#if defined HAVE_PUTUTLINE
	106	utmpname(UTMP_FILE);
	107	setutent();
	108	pututline(&utmp_entry);
	109	endutent();
	110	#endif
	111
	112	if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
	113	fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
	114	fclose(wtmp);
	115	}
	116
	117	#ifdef HAVE_LASTLOG
	118	memset(&lastlog_entry, 0, sizeof(lastlog_entry));
	119	strncpy(lastlog_entry.ll_line, ttyname+5, lenof(lastlog_entry.ll_line));
	120	strncpy(lastlog_entry.ll_host, location, lenof(lastlog_entry.ll_host));
	121	time(&lastlog_entry.ll_time);
	122	if ((lastlog = fopen(LASTLOG_FILE, "r+")) != NULL) {
	123	fseek(lastlog, sizeof(lastlog_entry) * getuid(), SEEK_SET);
	124	fwrite(&lastlog_entry, 1, sizeof(lastlog_entry), lastlog);
	125	fclose(lastlog);
	126	}
	127	#endif
	128
f51dc031	129	pty_stamped_utmp = 1;
f51dc031	130
755a6d84	131	#endif
	132	}
	133
	134	static void cleanup_utmp(void)
	135	{
	136	#ifndef OMIT_UTMP
	137	FILE *wtmp;
	138
95c47834	139	if (!pty_stamped_utmp)
f51dc031	140	return;
f51dc031	141
755a6d84	142	utmp_entry.ut_type = DEAD_PROCESS;
	143	memset(utmp_entry.ut_user, 0, lenof(utmp_entry.ut_user));
	144	time(&utmp_entry.ut_time);
	145
	146	if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) {
	147	fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp);
	148	fclose(wtmp);
	149	}
	150
	151	memset(utmp_entry.ut_line, 0, lenof(utmp_entry.ut_line));
	152	utmp_entry.ut_time = 0;
	153
	154	#if defined HAVE_PUTUTLINE
	155	utmpname(UTMP_FILE);
	156	setutent();
	157	pututline(&utmp_entry);
	158	endutent();
	159	#endif
	160
f51dc031	161	pty_stamped_utmp = 0; /* ensure we never double-cleanup */
755a6d84	162	#endif
	163	}
	164
a0e16eb1	165	static void sigchld_handler(int signum)
a0e16eb1	166	{
0f33f9d1	167	int save_errno = errno;
a0e16eb1	168	pid_t pid;
a0e16eb1	169	int status;
0f33f9d1	170
dfa1197d	171	do {
	172	pid = waitpid(-1, &status, WNOHANG);
	173	if (pid == pty_child_pid && (WIFEXITED(status) \|\| WIFSIGNALED(status))) {
	174	pty_exit_code = status;
	175	pty_child_dead = TRUE;
	176	}
	177	} while(pid > 0);
0f33f9d1	178	errno = save_errno;
a0e16eb1	179	}
a0e16eb1	180
755a6d84	181	static void fatal_sig_handler(int signum)
755a6d84	182	{
0f33f9d1	183	putty_signal(signum, SIG_DFL);
755a6d84	184	cleanup_utmp();
	185	setuid(getuid());
	186	raise(signum);
	187	}
	188
95c47834	189	static void pty_open_master(void)
1709795f	190	{
be4f86de	191	#ifdef BSD_PTYS
95c47834	192	const char chars1[] = "pqrstuvwxyz";
	193	const char chars2[] = "0123456789abcdef";
	194	const char p1, p2;
	195	char master_name[20];
	196	struct group *gp;
	197
	198	for (p1 = chars1; *p1; p1++)
	199	for (p2 = chars2; *p2; p2++) {
	200	sprintf(master_name, "/dev/pty%c%c", p1, p2);
	201	pty_master_fd = open(master_name, O_RDWR);
	202	if (pty_master_fd >= 0) {
	203	if (geteuid() == 0 \|\|
	204	access(master_name, R_OK \| W_OK) == 0)
	205	goto got_one;
	206	close(pty_master_fd);
be4f86de	207	}
95c47834	208	}
be4f86de	209
95c47834	210	/* If we get here, we couldn't get a tty at all. */
	211	fprintf(stderr, "pterm: unable to open a pseudo-terminal device\n");
	212	exit(1);
be4f86de	213
95c47834	214	got_one:
	215	strcpy(pty_name, master_name);
	216	pty_name[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */
	217
	218	/* We need to chown/chmod the /dev/ttyXX device. */
	219	gp = getgrnam("tty");
	220	chown(pty_name, getuid(), gp ? gp->gr_gid : -1);
	221	chmod(pty_name, 0600);
be4f86de	222	#else
054d8535	223	pty_master_fd = open("/dev/ptmx", O_RDWR);
	224
	225	if (pty_master_fd < 0) {
	226	perror("/dev/ptmx: open");
	227	exit(1);
	228	}
	229
	230	if (grantpt(pty_master_fd) < 0) {
	231	perror("grantpt");
	232	exit(1);
	233	}
	234
	235	if (unlockpt(pty_master_fd) < 0) {
	236	perror("unlockpt");
	237	exit(1);
	238	}
	239
95c47834	240	pty_name[FILENAME_MAX-1] = '\0';
95c47834	241	strncpy(pty_name, ptsname(pty_master_fd), FILENAME_MAX-1);
be4f86de	242	#endif
95c47834	243	}
054d8535	244
95c47834	245	/*
	246	* Pre-initialisation. This is here to get around the fact that GTK
	247	* doesn't like being run in setuid/setgid programs (probably
	248	* sensibly). So before we initialise GTK - and therefore before we
	249	* even process the command line - we check to see if we're running
	250	* set[ug]id. If so, we open our pty master _now_, chown it as
	251	* necessary, and drop privileges. We can always close it again
	252	* later. If we're potentially going to be doing utmp as well, we
	253	* also fork off a utmp helper process and communicate with it by
	254	* means of a pipe; the utmp helper will keep privileges in order
	255	* to clean up utmp when we exit (i.e. when its end of our pipe
	256	* closes).
	257	*/
	258	void pty_pre_init(void)
	259	{
	260	pid_t pid;
	261	int pipefd[2];
	262
0f33f9d1	263	/* set the child signal handler straight away; it needs to be set
	264	* before we ever fork. */
	265	putty_signal(SIGCHLD, sigchld_handler);
95c47834	266	pty_master_fd = -1;
	267
	268	if (geteuid() != getuid() \|\| getegid() != getgid()) {
	269	pty_open_master();
39baeaa4	270	}
39baeaa4	271
95c47834	272	#ifndef OMIT_UTMP
39baeaa4	273	/*
95c47834	274	* Fork off the utmp helper.
755a6d84	275	*/
95c47834	276	if (pipe(pipefd) < 0) {
	277	perror("pterm: pipe");
	278	exit(1);
	279	}
	280	pid = fork();
	281	if (pid < 0) {
	282	perror("pterm: fork");
	283	exit(1);
	284	} else if (pid == 0) {
	285	char display[128], buffer[128];
	286	int dlen, ret;
	287
	288	close(pipefd[1]);
	289	/*
	290	* Now sit here until we receive a display name from the
	291	* other end of the pipe, and then stamp utmp. Unstamp utmp
	292	* again, and exit, when the pipe closes.
	293	*/
	294
	295	dlen = 0;
	296	while (1) {
	297
	298	ret = read(pipefd[0], buffer, lenof(buffer));
	299	if (ret <= 0) {
	300	cleanup_utmp();
0f33f9d1	301	_exit(0);
95c47834	302	} else if (!pty_stamped_utmp) {
	303	if (dlen < lenof(display))
	304	memcpy(display+dlen, buffer,
	305	min(ret, lenof(display)-dlen));
	306	if (buffer[ret-1] == '\0') {
	307	/*
	308	* Now we have a display name. NUL-terminate
	309	* it, and stamp utmp.
	310	*/
	311	display[lenof(display)-1] = '\0';
	312	/*
	313	* Trap as many fatal signals as we can in the
	314	* hope of having the best possible chance to
	315	* clean up utmp before termination. We are
	316	* unfortunately unprotected against SIGKILL,
	317	* but that's life.
	318	*/
0f33f9d1	319	putty_signal(SIGHUP, fatal_sig_handler);
	320	putty_signal(SIGINT, fatal_sig_handler);
	321	putty_signal(SIGQUIT, fatal_sig_handler);
	322	putty_signal(SIGILL, fatal_sig_handler);
	323	putty_signal(SIGABRT, fatal_sig_handler);
	324	putty_signal(SIGFPE, fatal_sig_handler);
	325	putty_signal(SIGPIPE, fatal_sig_handler);
	326	putty_signal(SIGALRM, fatal_sig_handler);
	327	putty_signal(SIGTERM, fatal_sig_handler);
	328	putty_signal(SIGSEGV, fatal_sig_handler);
	329	putty_signal(SIGUSR1, fatal_sig_handler);
	330	putty_signal(SIGUSR2, fatal_sig_handler);
755a6d84	331	#ifdef SIGBUS
0f33f9d1	332	putty_signal(SIGBUS, fatal_sig_handler);
755a6d84	333	#endif
755a6d84	334	#ifdef SIGPOLL
0f33f9d1	335	putty_signal(SIGPOLL, fatal_sig_handler);
755a6d84	336	#endif
755a6d84	337	#ifdef SIGPROF
0f33f9d1	338	putty_signal(SIGPROF, fatal_sig_handler);
755a6d84	339	#endif
755a6d84	340	#ifdef SIGSYS
0f33f9d1	341	putty_signal(SIGSYS, fatal_sig_handler);
755a6d84	342	#endif
755a6d84	343	#ifdef SIGTRAP
0f33f9d1	344	putty_signal(SIGTRAP, fatal_sig_handler);
755a6d84	345	#endif
755a6d84	346	#ifdef SIGVTALRM
0f33f9d1	347	putty_signal(SIGVTALRM, fatal_sig_handler);
755a6d84	348	#endif
755a6d84	349	#ifdef SIGXCPU
0f33f9d1	350	putty_signal(SIGXCPU, fatal_sig_handler);
755a6d84	351	#endif
755a6d84	352	#ifdef SIGXFSZ
0f33f9d1	353	putty_signal(SIGXFSZ, fatal_sig_handler);
755a6d84	354	#endif
755a6d84	355	#ifdef SIGIO
0f33f9d1	356	putty_signal(SIGIO, fatal_sig_handler);
95c47834	357	#endif
95c47834	358	setup_utmp(pty_name, display);
	359	}
	360	}
	361	}
	362	} else {
	363	close(pipefd[0]);
	364	pty_utmp_helper_pid = pid;
	365	pty_utmp_helper_pipe = pipefd[1];
	366	}
755a6d84	367	#endif
95c47834	368
	369	/* Drop privs. */
	370	{
	371	int gid = getgid(), uid = getuid();
	372	#ifndef HAVE_NO_SETRESUID
	373	int setresgid(gid_t, gid_t, gid_t);
	374	int setresuid(uid_t, uid_t, uid_t);
	375	setresgid(gid, gid, gid);
	376	setresuid(uid, uid, uid);
	377	#else
	378	setgid(getgid());
	379	setuid(getuid());
	380	#endif
	381	}
	382	}
	383
	384	/*
	385	* Called to set up the pty.
	386	*
	387	* Returns an error message, or NULL on success.
	388	*
	389	* Also places the canonical host name into `realhost'. It must be
	390	* freed by the caller.
	391	*/
86916870	392	static char pty_init(void frontend, void *backend_handle, Config cfg,
887035a5	393	char host, int port, char *realhost, int nodelay)
95c47834	394	{
	395	int slavefd;
	396	pid_t pid, pgrp;
7af753e6	397	long windowid;
95c47834	398
a8327734	399	pty_frontend = frontend;
28d00fe4	400	backend_handle = NULL; / we can't sensibly use this, sadly */
28d00fe4	401
86916870	402	pty_term_width = cfg->width;
86916870	403	pty_term_height = cfg->height;
f278d6f8	404
95c47834	405	if (pty_master_fd < 0)
	406	pty_open_master();
	407
	408	/*
	409	* Set the backspace character to be whichever of ^H and ^? is
	410	* specified by bksp_is_delete.
	411	*/
	412	{
	413	struct termios attrs;
	414	tcgetattr(pty_master_fd, &attrs);
86916870	415	attrs.c_cc[VERASE] = cfg->bksp_is_delete ? '\177' : '\010';
95c47834	416	tcsetattr(pty_master_fd, TCSANOW, &attrs);
	417	}
	418
	419	/*
	420	* Stamp utmp (that is, tell the utmp helper process to do so),
	421	* or not.
	422	*/
86916870	423	if (!cfg->stamp_utmp)
95c47834	424	close(pty_utmp_helper_pipe); /* just let the child process die */
95c47834	425	else {
a8327734	426	char *location = get_x_display(pty_frontend);
95c47834	427	int len = strlen(location)+1, pos = 0; /* +1 to include NUL */
	428	while (pos < len) {
	429	int ret = write(pty_utmp_helper_pipe, location+pos, len - pos);
	430	if (ret < 0) {
	431	perror("pterm: writing to utmp helper process");
	432	close(pty_utmp_helper_pipe); /* arrgh, just give up */
	433	break;
	434	}
	435	pos += ret;
	436	}
	437	}
755a6d84	438
7af753e6	439	windowid = get_windowid(pty_frontend);
7af753e6	440
755a6d84	441	/*
054d8535	442	* Fork and execute the command.
	443	*/
	444	pid = fork();
	445	if (pid < 0) {
	446	perror("fork");
88e6b9ca	447	exit(1);
054d8535	448	}
	449
	450	if (pid == 0) {
	451	int i;
	452	/*
	453	* We are the child.
	454	*/
d37c2d81	455
95c47834	456	slavefd = open(pty_name, O_RDWR);
d37c2d81	457	if (slavefd < 0) {
d37c2d81	458	perror("slave pty: open");
0f33f9d1	459	_exit(1);
d37c2d81	460	}
d37c2d81	461
054d8535	462	close(pty_master_fd);
054d8535	463	fcntl(slavefd, F_SETFD, 0); /* don't close on exec */
	464	dup2(slavefd, 0);
	465	dup2(slavefd, 1);
	466	dup2(slavefd, 2);
	467	setsid();
d37c2d81	468	ioctl(slavefd, TIOCSCTTY, 1);
	469	pgrp = getpid();
	470	tcsetpgrp(slavefd, pgrp);
	471	setpgrp();
95c47834	472	close(open(pty_name, O_WRONLY, 0));
054d8535	473	setpgrp();
054d8535	474	/* Close everything _else_, for tidiness. */
	475	for (i = 3; i < 1024; i++)
	476	close(i);
fe9548aa	477	{
86916870	478	char term_env_var[10 + sizeof(cfg->termtype)];
86916870	479	sprintf(term_env_var, "TERM=%s", cfg->termtype);
fe9548aa	480	putenv(term_env_var);
fe9548aa	481	}
7af753e6	482	{
	483	char windowid_env_var[40];
	484	sprintf(windowid_env_var, "WINDOWID=%ld", windowid);
	485	putenv(windowid_env_var);
	486	}
8bf5c419	487	/*
	488	* SIGINT and SIGQUIT may have been set to ignored by our
	489	* parent, particularly by things like sh -c 'pterm &' and
	490	* some window managers. Reverse this for our child process.
	491	*/
0f33f9d1	492	putty_signal(SIGINT, SIG_DFL);
0f33f9d1	493	putty_signal(SIGQUIT, SIG_DFL);
6169c758	494	if (pty_argv)
6169c758	495	execvp(pty_argv[0], pty_argv);
c8ee61b9	496	else {
	497	char *shell = getenv("SHELL");
	498	char *shellname;
86916870	499	if (cfg->login_shell) {
c8ee61b9	500	char *p = strrchr(shell, '/');
3d88e64d	501	shellname = snewn(2+strlen(shell), char);
c8ee61b9	502	p = p ? p+1 : shell;
	503	sprintf(shellname, "-%s", p);
	504	} else
	505	shellname = shell;
	506	execl(getenv("SHELL"), shellname, NULL);
	507	}
	508
054d8535	509	/*
	510	* If we're here, exec has gone badly foom.
	511	*/
	512	perror("exec");
0f33f9d1	513	_exit(127);
054d8535	514	} else {
a0e16eb1	515	pty_child_pid = pid;
a0e16eb1	516	pty_child_dead = FALSE;
0f33f9d1	517	}
054d8535	518
1709795f	519	return NULL;
	520	}
	521
	522	/*
86916870	523	* Stub routine (we don't have any need to reconfigure this backend).
	524	*/
	525	static void pty_reconfig(void handle, Config cfg)
	526	{
	527	}
	528
	529	/*
cb60dcb3	530	* Stub routine (never called in pterm
	531	*/
	532	static void pty_free(void *handle)
	533	{
	534	}
	535
	536
	537	/*
1709795f	538	* Called to send data down the pty.
1709795f	539	*/
28d00fe4	540	static int pty_send(void handle, char buf, int len)
1709795f	541	{
90cfd8f4	542	if (pty_master_fd < 0)
	543	return 0; /* ignore all writes if fd closed */
	544
054d8535	545	while (len > 0) {
	546	int ret = write(pty_master_fd, buf, len);
	547	if (ret < 0) {
	548	perror("write pty master");
	549	exit(1);
	550	}
	551	buf += ret;
	552	len -= ret;
	553	}
1709795f	554	return 0;
	555	}
	556
90cfd8f4	557	void pty_close(void)
	558	{
	559	if (pty_master_fd >= 0) {
	560	close(pty_master_fd);
	561	pty_master_fd = -1;
	562	}
	563	close(pty_utmp_helper_pipe); /* this causes utmp to be cleaned up */
	564	}
	565
1709795f	566	/*
	567	* Called to query the current socket sendability status.
	568	*/
28d00fe4	569	static int pty_sendbuffer(void *handle)
1709795f	570	{
	571	return 0;
	572	}
	573
	574	/*
	575	* Called to set the size of the window
	576	*/
28d00fe4	577	static void pty_size(void *handle, int width, int height)
1709795f	578	{
88e6b9ca	579	struct winsize size;
88e6b9ca	580
f278d6f8	581	pty_term_width = width;
	582	pty_term_height = height;
	583
	584	size.ws_row = (unsigned short)pty_term_height;
	585	size.ws_col = (unsigned short)pty_term_width;
a8327734	586	size.ws_xpixel = (unsigned short) pty_term_width *
	587	font_dimension(pty_frontend, 0);
	588	size.ws_ypixel = (unsigned short) pty_term_height *
	589	font_dimension(pty_frontend, 1);
88e6b9ca	590	ioctl(pty_master_fd, TIOCSWINSZ, (void *)&size);
1709795f	591	return;
	592	}
	593
	594	/*
	595	* Send special codes.
	596	*/
28d00fe4	597	static void pty_special(void *handle, Telnet_Special code)
1709795f	598	{
	599	/* Do nothing! */
	600	return;
	601	}
	602
28d00fe4	603	static Socket pty_socket(void *handle)
1709795f	604	{
	605	return NULL; /* shouldn't ever be needed */
	606	}
	607
28d00fe4	608	static int pty_sendok(void *handle)
1709795f	609	{
	610	return 1;
	611	}
	612
28d00fe4	613	static void pty_unthrottle(void *handle, int backlog)
1709795f	614	{
	615	/* do nothing */
	616	}
	617
28d00fe4	618	static int pty_ldisc(void *handle, int option)
1709795f	619	{
	620	return 0; /* neither editing nor echoing */
	621	}
	622
b9d7bcad	623	static void pty_provide_ldisc(void handle, void ldisc)
	624	{
	625	/* This is a stub. */
	626	}
	627
a8327734	628	static void pty_provide_logctx(void handle, void logctx)
	629	{
	630	/* This is a stub. */
	631	}
	632
28d00fe4	633	static int pty_exitcode(void *handle)
1709795f	634	{
90cfd8f4	635	if (!pty_child_dead)
	636	return -1; /* not dead yet */
	637	else
	638	return pty_exit_code;
1709795f	639	}
	640
	641	Backend pty_backend = {
	642	pty_init,
cb60dcb3	643	pty_free,
86916870	644	pty_reconfig,
1709795f	645	pty_send,
	646	pty_sendbuffer,
	647	pty_size,
	648	pty_special,
	649	pty_socket,
	650	pty_exitcode,
	651	pty_sendok,
	652	pty_ldisc,
b9d7bcad	653	pty_provide_ldisc,
a8327734	654	pty_provide_logctx,
1709795f	655	pty_unthrottle,
	656	1
	657	};