Adding upstream version 2.39.3.upstream/2.39.3

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 861 insertions, 0 deletions

diff --git a/lib/pty-session.c b/lib/pty-session.c
new file mode 100644
index 0000000..3849065
--- /dev/null
+++ b/lib/pty-session.c
@@ -0,0 +1,861 @@
+/*
+ * This is pseudo-terminal container for child process where parent creates a
+ * proxy between the current std{in,out,etrr} and the child's pty. Advantages:
+ *
+ * - child has no access to parent's terminal (e.g. su --pty)
+ * - parent can log all traffic between user and child's terminal (e.g. script(1))
+ * - it's possible to start commands on terminal although parent has no terminal
+ *
+ * This code is in the public domain; do with it what you wish.
+ *
+ * Written by Karel Zak <kzak@redhat.com> in Jul 2019
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <pty.h>
+#include <poll.h>
+#include <sys/signalfd.h>
+#include <paths.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <inttypes.h>
+
+#include "c.h"
+#include "all-io.h"
+#include "ttyutils.h"
+#include "pty-session.h"
+#include "monotonic.h"
+#include "debug.h"
+
+static UL_DEBUG_DEFINE_MASK(ulpty);
+UL_DEBUG_DEFINE_MASKNAMES(ulpty) = UL_DEBUG_EMPTY_MASKNAMES;
+
+#define ULPTY_DEBUG_INIT	(1 << 1)
+#define ULPTY_DEBUG_SETUP	(1 << 2)
+#define ULPTY_DEBUG_SIG		(1 << 3)
+#define ULPTY_DEBUG_IO		(1 << 4)
+#define ULPTY_DEBUG_DONE	(1 << 5)
+#define ULPTY_DEBUG_ALL		0xFFFF
+
+#define DBG(m, x)       __UL_DBG(ulpty, ULPTY_DEBUG_, m, x)
+#define ON_DBG(m, x)    __UL_DBG_CALL(ulpty, ULPTY_DEBUG_, m, x)
+
+#define UL_DEBUG_CURRENT_MASK   UL_DEBUG_MASK(ulpty)
+#include "debugobj.h"
+
+void ul_pty_init_debug(int mask)
+{
+	if (ulpty_debug_mask)
+		return;
+	__UL_INIT_DEBUG_FROM_ENV(ulpty, ULPTY_DEBUG_, mask, ULPTY_DEBUG);
+}
+
+struct ul_pty *ul_new_pty(int is_stdin_tty)
+{
+	struct ul_pty *pty = calloc(1, sizeof(*pty));
+
+	if (!pty)
+		return NULL;
+
+	DBG(SETUP, ul_debugobj(pty, "alloc handler"));
+	pty->isterm = is_stdin_tty;
+	pty->master = -1;
+	pty->slave = -1;
+	pty->sigfd = -1;
+	pty->child = (pid_t) -1;
+
+	return pty;
+}
+
+void ul_free_pty(struct ul_pty *pty)
+{
+	struct ul_pty_child_buffer *hd;
+
+	while ((hd = pty->child_buffer_head)) {
+		pty->child_buffer_head = hd->next;
+		free(hd);
+	}
+
+	while ((hd = pty->free_buffers)) {
+		pty->free_buffers = hd->next;
+		free(hd);
+	}
+	free(pty);
+}
+
+void ul_pty_slave_echo(struct ul_pty *pty, int enable)
+{
+	assert(pty);
+	pty->slave_echo = enable ? 1 : 0;
+}
+
+int ul_pty_get_delivered_signal(struct ul_pty *pty)
+{
+	assert(pty);
+	return pty->delivered_signal;
+}
+
+struct ul_pty_callbacks *ul_pty_get_callbacks(struct ul_pty *pty)
+{
+	assert(pty);
+	return &pty->callbacks;
+}
+
+void ul_pty_set_callback_data(struct ul_pty *pty, void *data)
+{
+	assert(pty);
+	pty->callback_data = data;
+}
+
+void ul_pty_set_child(struct ul_pty *pty, pid_t child)
+{
+	assert(pty);
+	pty->child = child;
+}
+
+int ul_pty_get_childfd(struct ul_pty *pty)
+{
+	assert(pty);
+	return pty->master;
+}
+
+pid_t ul_pty_get_child(struct ul_pty *pty)
+{
+	assert(pty);
+	return pty->child;
+}
+
+/* it's active when signals are redirected to sigfd */
+int ul_pty_is_running(struct ul_pty *pty)
+{
+	assert(pty);
+	return pty->sigfd >= 0;
+}
+
+void ul_pty_set_mainloop_time(struct ul_pty *pty, struct timeval *tv)
+{
+	assert(pty);
+	if (!tv) {
+		DBG(IO, ul_debugobj(pty, "mainloop time: clear"));
+		timerclear(&pty->next_callback_time);
+	} else {
+		pty->next_callback_time.tv_sec = tv->tv_sec;
+		pty->next_callback_time.tv_usec = tv->tv_usec;
+		DBG(IO, ul_debugobj(pty, "mainloop time: %"PRId64".%06"PRId64,
+				(int64_t) tv->tv_sec, (int64_t) tv->tv_usec));
+	}
+}
+
+static void pty_signals_cleanup(struct ul_pty *pty)
+{
+	if (pty->sigfd != -1)
+		close(pty->sigfd);
+	pty->sigfd = -1;
+
+	/* restore original setting */
+	sigprocmask(SIG_SETMASK, &pty->orgsig, NULL);
+}
+
+/* call me before fork() */
+int ul_pty_setup(struct ul_pty *pty)
+{
+	struct termios attrs;
+	int rc = 0;
+
+	assert(pty->sigfd == -1);
+
+	/* save the current signals setting (to make ul_pty_cleanup() usable,
+	 * otherwise see ul_pty_signals_setup() */
+	sigprocmask(0, NULL, &pty->orgsig);
+
+	if (pty->isterm) {
+	        DBG(SETUP, ul_debugobj(pty, "create for terminal"));
+
+		/* original setting of the current terminal */
+		if (tcgetattr(STDIN_FILENO, &pty->stdin_attrs) != 0) {
+			rc = -errno;
+			goto done;
+		}
+
+		attrs = pty->stdin_attrs;
+		if (pty->slave_echo)
+			attrs.c_lflag |= ECHO;
+		else
+			attrs.c_lflag &= ~ECHO;
+
+		ioctl(STDIN_FILENO, TIOCGWINSZ, (char *)&pty->win);
+		/* create master+slave */
+		rc = openpty(&pty->master, &pty->slave, NULL, &attrs, &pty->win);
+		if (rc)
+			goto done;
+
+		/* set the current terminal to raw mode; pty_cleanup() reverses this change on exit */
+		cfmakeraw(&attrs);
+		tcsetattr(STDIN_FILENO, TCSANOW, &attrs);
+	} else {
+		DBG(SETUP, ul_debugobj(pty, "create for non-terminal"));
+
+		rc = openpty(&pty->master, &pty->slave, NULL, NULL, NULL);
+		if (rc)
+			goto done;
+
+		tcgetattr(pty->slave, &attrs);
+
+		if (pty->slave_echo)
+			attrs.c_lflag |= ECHO;
+		else
+			attrs.c_lflag &= ~ECHO;
+
+		tcsetattr(pty->slave, TCSANOW, &attrs);
+	}
+
+	fcntl(pty->master, F_SETFL, O_NONBLOCK);
+
+done:
+	if (rc)
+		ul_pty_cleanup(pty);
+
+	DBG(SETUP, ul_debugobj(pty, "pty setup done [master=%d, slave=%d, rc=%d]",
+				pty->master, pty->slave, rc));
+	return rc;
+}
+
+/* call me before fork() */
+int ul_pty_signals_setup(struct ul_pty *pty)
+{
+	sigset_t ourset;
+	int rc = 0;
+
+	assert(pty->sigfd == -1);
+
+	/* save the current signals setting */
+	sigprocmask(0, NULL, &pty->orgsig);
+
+	sigfillset(&ourset);
+	if (sigprocmask(SIG_BLOCK, &ourset, NULL)) {
+		rc = -errno;
+		goto done;
+	}
+
+	sigemptyset(&ourset);
+	sigaddset(&ourset, SIGCHLD);
+	sigaddset(&ourset, SIGWINCH);
+	sigaddset(&ourset, SIGALRM);
+	sigaddset(&ourset, SIGTERM);
+	sigaddset(&ourset, SIGINT);
+	sigaddset(&ourset, SIGQUIT);
+
+	if (pty->callbacks.flush_logs)
+		sigaddset(&ourset, SIGUSR1);
+
+	if ((pty->sigfd = signalfd(-1, &ourset, SFD_CLOEXEC)) < 0)
+		rc = -errno;
+done:
+	if (rc)
+		ul_pty_cleanup(pty);
+
+	DBG(SETUP, ul_debugobj(pty, "pty signals setup done [rc=%d]", rc));
+	return rc;
+}
+
+/* cleanup in parent process */
+void ul_pty_cleanup(struct ul_pty *pty)
+{
+	struct termios rtt;
+
+	pty_signals_cleanup(pty);
+
+	if (pty->master == -1 || !pty->isterm)
+		return;
+
+	DBG(DONE, ul_debugobj(pty, "cleanup"));
+	rtt = pty->stdin_attrs;
+	tcsetattr(STDIN_FILENO, TCSADRAIN, &rtt);
+}
+
+int ul_pty_chownmod_slave(struct ul_pty *pty, uid_t uid, gid_t gid, mode_t mode)
+{
+	if (fchown(pty->slave, uid, gid))
+		return -errno;
+	if (fchmod(pty->slave, mode))
+		return -errno;
+	return 0;
+}
+
+/* call me in child process */
+void ul_pty_init_slave(struct ul_pty *pty)
+{
+	DBG(SETUP, ul_debugobj(pty, "initialize slave"));
+
+	setsid();
+
+	ioctl(pty->slave, TIOCSCTTY, 1);
+	close(pty->master);
+
+	dup2(pty->slave, STDIN_FILENO);
+	dup2(pty->slave, STDOUT_FILENO);
+	dup2(pty->slave, STDERR_FILENO);
+
+	close(pty->slave);
+
+	if (pty->sigfd >= 0)
+		close(pty->sigfd);
+
+	pty->slave = -1;
+	pty->master = -1;
+	pty->sigfd = -1;
+
+	sigprocmask(SIG_SETMASK, &pty->orgsig, NULL);
+
+	DBG(SETUP, ul_debugobj(pty, "... initialize slave done"));
+}
+
+static int write_output(char *obuf, ssize_t bytes)
+{
+	DBG(IO, ul_debug(" writing output"));
+
+	if (write_all(STDOUT_FILENO, obuf, bytes)) {
+		DBG(IO, ul_debug("  writing output *failed*"));
+		return -errno;
+	}
+
+	return 0;
+}
+
+static int schedule_child_write(struct ul_pty *pty, char *buf, size_t bufsz, int final)
+{
+	struct ul_pty_child_buffer *stash;
+
+	if (pty->free_buffers) {
+		stash = pty->free_buffers;
+		pty->free_buffers = stash->next;
+		memset(stash, 0, sizeof(*stash));
+	} else
+		stash = calloc(1, sizeof(*stash));
+	if (!stash)
+		return -1;
+
+	assert(bufsz <= sizeof(stash->buf));
+
+	memcpy(stash->buf, buf, bufsz);
+	stash->size = bufsz;
+	stash->final_input = final ? 1 : 0;
+
+	if (pty->child_buffer_head)
+		pty->child_buffer_tail = pty->child_buffer_tail->next = stash;
+	else
+		pty->child_buffer_head = pty->child_buffer_tail = stash;
+	return 0;
+}
+
+/*
+ * The pty is usually faster than shell, so it's a good idea to wait until
+ * the previous message has been already read by shell from slave before we
+ * write to master. This is necessary especially for EOF situation when we can
+ * send EOF to master before shell is fully initialized, to workaround this
+ * problem we wait until slave is empty. For example:
+ *
+ *   echo "date" | su --pty
+ *
+ * Unfortunately, the child (usually shell) can ignore stdin at all, so we
+ * don't wait forever to avoid dead locks...
+ *
+ * Note that su --pty is primarily designed for interactive sessions as it
+ * maintains master+slave tty stuff within the session. Use pipe to write to
+ * pty and assume non-interactive (tee-like) behavior is NOT well supported.
+ */
+static void drain_child_buffers(struct ul_pty *pty)
+{
+	unsigned int tries = 0;
+	struct pollfd fd = { .fd = pty->slave, .events = POLLIN };
+
+	DBG(IO, ul_debugobj(pty, " waiting for empty slave"));
+	while (poll(&fd, 1, 10) == 1 && tries < 8) {
+		DBG(IO, ul_debugobj(pty, "   slave is not empty"));
+		xusleep(250000);
+		tries++;
+	}
+	if (tries < 8)
+		DBG(IO, ul_debugobj(pty, "   slave is empty now"));
+
+	DBG(IO, ul_debugobj(pty, " sending EOF to master"));
+}
+
+static int flush_child_buffers(struct ul_pty *pty, int *anything)
+{
+	int rc = 0, any = 0;
+
+	while (pty->child_buffer_head) {
+		struct ul_pty_child_buffer *hd = pty->child_buffer_head;
+		ssize_t ret;
+
+		if (hd->final_input)
+			drain_child_buffers(pty);
+
+		DBG(IO, ul_debugobj(hd, " stdin --> master trying %zu bytes", hd->size - hd->cursor));
+
+		ret = write(pty->master, hd->buf + hd->cursor, hd->size - hd->cursor);
+		if (ret == -1) {
+			DBG(IO, ul_debugobj(hd, "   EAGAIN"));
+			if (!(errno == EINTR || errno == EAGAIN))
+				rc = -errno;
+			goto out;
+		}
+		DBG(IO, ul_debugobj(hd, "   wrote %zd", ret));
+		any = 1;
+		hd->cursor += ret;
+
+		if (hd->cursor == hd->size) {
+			pty->child_buffer_head = hd->next;
+			if (!hd->next)
+				pty->child_buffer_tail = NULL;
+
+			hd->next = pty->free_buffers;
+			pty->free_buffers = hd;
+		}
+	}
+out:
+	/* without sync write_output() will write both input &
+	 * shell output that looks like double echoing */
+	if (any)
+		fdatasync(pty->master);
+
+	if (anything)
+		*anything = any;
+	return rc;
+}
+
+void ul_pty_write_eof_to_child(struct ul_pty *pty)
+{
+	char c = DEF_EOF;
+	schedule_child_write(pty, &c, sizeof(char), 1);
+}
+
+static int mainloop_callback(struct ul_pty *pty)
+{
+	int rc;
+
+	if (!pty->callbacks.mainloop)
+		return 0;
+
+	DBG(IO, ul_debugobj(pty, "calling mainloop callback"));
+	rc = pty->callbacks.mainloop(pty->callback_data);
+
+	DBG(IO, ul_debugobj(pty, " callback done [rc=%d]", rc));
+	return rc;
+}
+
+static int handle_io(struct ul_pty *pty, int fd, int *eof)
+{
+	char buf[BUFSIZ];
+	ssize_t bytes;
+	int rc = 0;
+	sigset_t set;
+
+	DBG(IO, ul_debugobj(pty, " handle I/O on fd=%d", fd));
+	*eof = 0;
+
+	sigemptyset(&set);
+	sigaddset(&set, SIGTTIN);
+	sigprocmask(SIG_UNBLOCK, &set, NULL);
+	/* read from active FD */
+	bytes = read(fd, buf, sizeof(buf));
+	sigprocmask(SIG_BLOCK, &set, NULL);
+	if (bytes == -1) {
+		if (errno == EAGAIN || errno == EINTR)
+			return 0;
+		return -errno;
+	}
+
+	if (bytes == 0) {
+		*eof = 1;
+		return 0;
+	}
+
+	/* from stdin (user) to command */
+	if (fd == STDIN_FILENO) {
+		DBG(IO, ul_debugobj(pty, " stdin --> master %zd bytes queued", bytes));
+
+		if (schedule_child_write(pty, buf, bytes, 0))
+			return -errno;
+
+	/* from command (master) to stdout */
+	} else if (fd == pty->master) {
+		DBG(IO, ul_debugobj(pty, " master --> stdout %zd bytes", bytes));
+		write_output(buf, bytes);
+	}
+
+	if (pty->callbacks.log_stream_activity)
+		rc = pty->callbacks.log_stream_activity(
+					pty->callback_data, fd, buf, bytes);
+
+	return rc;
+}
+
+void ul_pty_wait_for_child(struct ul_pty *pty)
+{
+	int status;
+	pid_t pid;
+	int options = 0;
+
+	if (pty->child == (pid_t) -1)
+		return;
+
+	DBG(SIG, ul_debug("waiting for child [child=%d]", (int) pty->child));
+
+	if (ul_pty_is_running(pty)) {
+		/* wait for specific child */
+		options = WNOHANG;
+		for (;;) {
+			pid = waitpid(pty->child, &status, options);
+			DBG(SIG, ul_debug(" waitpid done [rc=%d]", (int) pid));
+			if (pid != (pid_t) - 1) {
+				if (pty->callbacks.child_die)
+					pty->callbacks.child_die(
+							pty->callback_data,
+							pty->child, status);
+				ul_pty_set_child(pty, (pid_t) -1);
+			} else
+				break;
+		}
+	} else {
+		/* final wait */
+		while ((pid = waitpid(-1, &status, options)) > 0) {
+			DBG(SIG, ul_debug(" waitpid done [rc=%d]", (int) pid));
+			if (pid == pty->child) {
+				if (pty->callbacks.child_die)
+					pty->callbacks.child_die(
+							pty->callback_data,
+							pty->child, status);
+				ul_pty_set_child(pty, (pid_t) -1);
+			}
+		}
+	}
+}
+
+static int handle_signal(struct ul_pty *pty, int fd)
+{
+	struct signalfd_siginfo info;
+	ssize_t bytes;
+	int rc = 0;
+
+	DBG(SIG, ul_debugobj(pty, " handle signal on fd=%d", fd));
+
+	bytes = read(fd, &info, sizeof(info));
+	if (bytes != sizeof(info)) {
+		if (bytes < 0 && (errno == EAGAIN || errno == EINTR))
+			return 0;
+		return -errno;
+	}
+
+	switch (info.ssi_signo) {
+	case SIGCHLD:
+		DBG(SIG, ul_debugobj(pty, " get signal SIGCHLD"));
+
+		if (info.ssi_code == CLD_EXITED
+		    || info.ssi_code == CLD_KILLED
+		    || info.ssi_code == CLD_DUMPED) {
+
+			if (pty->callbacks.child_wait)
+				pty->callbacks.child_wait(pty->callback_data,
+							  pty->child);
+			else
+				ul_pty_wait_for_child(pty);
+
+		} else if (info.ssi_status == SIGSTOP && pty->child > 0) {
+			pty->callbacks.child_sigstop(pty->callback_data,
+						     pty->child);
+		}
+
+		if (pty->child <= 0) {
+			DBG(SIG, ul_debugobj(pty, " no child, setting leaving timeout"));
+			pty->poll_timeout = 10;
+			timerclear(&pty->next_callback_time);
+		}
+		return 0;
+	case SIGWINCH:
+		DBG(SIG, ul_debugobj(pty, " get signal SIGWINCH"));
+		if (pty->isterm) {
+			ioctl(STDIN_FILENO, TIOCGWINSZ, (char *)&pty->win);
+			ioctl(pty->slave, TIOCSWINSZ, (char *)&pty->win);
+
+			if (pty->callbacks.log_signal)
+				rc = pty->callbacks.log_signal(pty->callback_data,
+							&info, (void *) &pty->win);
+		}
+		break;
+	case SIGTERM:
+		/* fallthrough */
+	case SIGINT:
+		/* fallthrough */
+	case SIGQUIT:
+		DBG(SIG, ul_debugobj(pty, " get signal SIG{TERM,INT,QUIT}"));
+		pty->delivered_signal = info.ssi_signo;
+                /* Child termination is going to generate SIGCHLD (see above) */
+		if (pty->child > 0)
+	                kill(pty->child, SIGTERM);
+
+		if (pty->callbacks.log_signal)
+			rc = pty->callbacks.log_signal(pty->callback_data,
+					&info, (void *) &pty->win);
+		break;
+	case SIGUSR1:
+		DBG(SIG, ul_debugobj(pty, " get signal SIGUSR1"));
+		if (pty->callbacks.flush_logs)
+			rc = pty->callbacks.flush_logs(pty->callback_data);
+		break;
+	default:
+		abort();
+	}
+
+	return rc;
+}
+
+/* loop in parent */
+int ul_pty_proxy_master(struct ul_pty *pty)
+{
+	int rc = 0, ret, eof = 0;
+	enum {
+		POLLFD_SIGNAL = 0,
+		POLLFD_MASTER,
+		POLLFD_STDIN
+
+	};
+	struct pollfd pfd[] = {
+		[POLLFD_SIGNAL] = { .fd = -1,		.events = POLLIN | POLLERR | POLLHUP },
+		[POLLFD_MASTER] = { .fd = pty->master,  .events = POLLIN | POLLERR | POLLHUP },
+		[POLLFD_STDIN]	= { .fd = STDIN_FILENO, .events = POLLIN | POLLERR | POLLHUP }
+	};
+
+	/* We use signalfd, and standard signals by handlers are completely blocked */
+	assert(pty->sigfd >= 0);
+
+	pfd[POLLFD_SIGNAL].fd = pty->sigfd;
+	pty->poll_timeout = -1;
+
+	while (!pty->delivered_signal) {
+		size_t i;
+		int errsv, timeout;
+
+		DBG(IO, ul_debugobj(pty, "--poll() loop--"));
+
+		/* note, callback usually updates @next_callback_time */
+		if (timerisset(&pty->next_callback_time)) {
+			struct timeval now;
+
+			DBG(IO, ul_debugobj(pty, " callback requested"));
+			gettime_monotonic(&now);
+			if (timercmp(&now, &pty->next_callback_time, >)) {
+				rc = mainloop_callback(pty);
+				if (rc)
+					break;
+			}
+		}
+
+		/* set timeout */
+		if (timerisset(&pty->next_callback_time)) {
+			struct timeval now, rest;
+
+			gettime_monotonic(&now);
+			timersub(&pty->next_callback_time, &now, &rest);
+			timeout = (rest.tv_sec * 1000) +  (rest.tv_usec / 1000);
+		} else
+			timeout = pty->poll_timeout;
+
+		/* use POLLOUT (aka "writing is now possible") if data queued */
+		if (pty->child_buffer_head)
+			pfd[POLLFD_MASTER].events |= POLLOUT;
+		else
+			pfd[POLLFD_MASTER].events &= ~POLLOUT;
+
+		/* wait for input, signal or timeout */
+		DBG(IO, ul_debugobj(pty, "calling poll() [timeout=%dms]", timeout));
+		ret = poll(pfd, ARRAY_SIZE(pfd), timeout);
+
+		errsv = errno;
+		DBG(IO, ul_debugobj(pty, "poll() rc=%d", ret));
+
+		/* error */
+		if (ret < 0) {
+			if (errsv == EAGAIN)
+				continue;
+			rc = -errno;
+			break;
+		}
+
+		/* timeout */
+		if (ret == 0) {
+			if (timerisset(&pty->next_callback_time)) {
+				rc = mainloop_callback(pty);
+				if (rc == 0)
+					continue;
+			} else {
+				rc = 0;
+			}
+
+			DBG(IO, ul_debugobj(pty, "leaving poll() loop [timeout=%d, rc=%d]", timeout, rc));
+			break;
+		}
+		/* event */
+		for (i = 0; i < ARRAY_SIZE(pfd); i++) {
+			if (pfd[i].revents == 0)
+				continue;
+
+			DBG(IO, ul_debugobj(pty, " active pfd[%s].fd=%d %s %s %s %s %s",
+						i == POLLFD_STDIN  ? "stdin" :
+						i == POLLFD_MASTER ? "master" :
+						i == POLLFD_SIGNAL ? "signal" : "???",
+						pfd[i].fd,
+						pfd[i].revents & POLLIN  ? "POLLIN" : "",
+						pfd[i].revents & POLLOUT ? "POLLOUT" : "",
+						pfd[i].revents & POLLHUP ? "POLLHUP" : "",
+						pfd[i].revents & POLLERR ? "POLLERR" : "",
+						pfd[i].revents & POLLNVAL ? "POLLNVAL" : ""));
+
+			if (i == POLLFD_SIGNAL)
+				rc = handle_signal(pty, pfd[i].fd);
+			else {
+				if (pfd[i].revents & POLLIN)
+					rc = handle_io(pty, pfd[i].fd, &eof); /* data */
+				if (pfd[i].revents & POLLOUT) /* i == POLLFD_MASTER */
+					rc = flush_child_buffers(pty, NULL);
+			}
+
+			if (rc) {
+				int anything = 1;
+
+				ul_pty_write_eof_to_child(pty);
+				for (anything = 1; anything;)
+					flush_child_buffers(pty, &anything);
+				break;
+			}
+
+			if (i == POLLFD_SIGNAL)
+				continue;
+
+			/* EOF maybe detected in two ways; they are as follows:
+			 *	A) poll() return POLLHUP event after close()
+			 *	B) read() returns 0 (no data)
+			 *
+			 * POLLNVAL means that fd is closed.
+			 */
+			if ((pfd[i].revents & POLLHUP) || (pfd[i].revents & POLLNVAL) || eof) {
+				DBG(IO, ul_debugobj(pty, " ignore FD"));
+				if (i == POLLFD_STDIN) {
+					pfd[i].fd = -1;
+					ul_pty_write_eof_to_child(pty);
+				} else /* i == POLLFD_MASTER */
+					pfd[i].revents &= ~POLLIN;
+			}
+		}
+		if (rc)
+			break;
+	}
+
+	if (rc && pty->child && pty->child != (pid_t) -1 && !pty->delivered_signal) {
+		kill(pty->child, SIGTERM);
+		sleep(2);
+		kill(pty->child, SIGKILL);
+	}
+
+	pty_signals_cleanup(pty);
+
+	DBG(IO, ul_debug("poll() done [signal=%d, rc=%d]", pty->delivered_signal, rc));
+	return rc;
+}
+
+#ifdef TEST_PROGRAM_PTY
+/*
+ * $ make test_pty
+ * $ ./test_pty
+ *
+ * ... and see for example tty(1) or "ps afu"
+ */
+static void child_sigstop(void *data __attribute__((__unused__)), pid_t child)
+{
+	kill(getpid(), SIGSTOP);
+	kill(child, SIGCONT);
+}
+
+int main(int argc, char *argv[])
+{
+	struct ul_pty_callbacks *cb;
+	const char *shell, *command = NULL, *shname = NULL;
+	int caught_signal = 0;
+	pid_t child;
+	struct ul_pty *pty;
+
+	shell = getenv("SHELL");
+	if (shell == NULL)
+		shell = _PATH_BSHELL;
+	if (argc == 2)
+		command = argv[1];
+
+	ul_pty_init_debug(0);
+
+	pty = ul_new_pty(isatty(STDIN_FILENO));
+	if (!pty)
+		err(EXIT_FAILURE, "failed to allocate PTY handler");
+
+	cb = ul_pty_get_callbacks(pty);
+	cb->child_sigstop = child_sigstop;
+
+	if (ul_pty_setup(pty))
+		err(EXIT_FAILURE, "failed to create pseudo-terminal");
+	if (ul_pty_signals_setup(pty))
+		err(EXIT_FAILURE, "failed to initialize signals handler");
+
+	fflush(stdout);			/* ??? */
+
+	switch ((int) (child = fork())) {
+	case -1: /* error */
+		ul_pty_cleanup(pty);
+		err(EXIT_FAILURE, "cannot create child process");
+		break;
+
+	case 0: /* child */
+		ul_pty_init_slave(pty);
+
+		signal(SIGTERM, SIG_DFL); /* because /etc/csh.login */
+
+		shname = strrchr(shell, '/');
+		shname = shname ? shname + 1 : shell;
+
+		if (command)
+			execl(shell, shname, "-c", command, (char *)NULL);
+		else
+			execl(shell, shname, "-i", (char *)NULL);
+		err(EXIT_FAILURE, "failed to execute %s", shell);
+		break;
+
+	default:
+		break;
+	}
+
+	/* parent */
+	ul_pty_set_child(pty, child);
+
+	/* this is the main loop */
+	ul_pty_proxy_master(pty);
+
+	/* all done; cleanup and kill */
+	caught_signal = ul_pty_get_delivered_signal(pty);
+
+	if (!caught_signal && ul_pty_get_child(pty) != (pid_t)-1)
+		ul_pty_wait_for_child(pty);	/* final wait */
+
+	if (caught_signal && ul_pty_get_child(pty) != (pid_t)-1) {
+		fprintf(stderr, "\nSession terminated, killing shell...");
+		kill(child, SIGTERM);
+		sleep(2);
+		kill(child, SIGKILL);
+		fprintf(stderr, " ...killed.\n");
+	}
+
+	ul_pty_cleanup(pty);
+	ul_free_pty(pty);
+	return EXIT_SUCCESS;
+}
+
+#endif /* TEST_PROGRAM */
+