chardev/char-pty.c - qemu - Git at Google

 /*
  * QEMU System Emulator
  *
  * Copyright (c) 2003-2008 Fabrice Bellard
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */

 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "chardev/char.h"
 #include "io/channel-file.h"
 #include "qemu/sockets.h"
 #include "qemu/error-report.h"
 #include "qemu/module.h"
 #include "qemu/option.h"
 #include "qemu/qemu-print.h"

 #include "chardev/char-io.h"
 #include "qom/object.h"

 struct PtyChardev {
     Chardev parent;
     QIOChannel *ioc;
     int read_bytes;

     int connected;
     GSource *timer_src;
     char *path;
 };
 typedef struct PtyChardev PtyChardev;

 DECLARE_INSTANCE_CHECKER(PtyChardev, PTY_CHARDEV,
                          TYPE_CHARDEV_PTY)

 static void pty_chr_state(Chardev *chr, int connected);

 static void pty_chr_timer_cancel(PtyChardev *s)
 {
     if (s->timer_src) {
         g_source_destroy(s->timer_src);
         g_source_unref(s->timer_src);
         s->timer_src = NULL;
     }
 }

 static gboolean pty_chr_timer(gpointer opaque)
 {
     struct Chardev *chr = CHARDEV(opaque);
     PtyChardev *s = PTY_CHARDEV(opaque);

     pty_chr_timer_cancel(s);
     if (!s->connected) {
         /* Next poll ... */
         qemu_chr_be_update_read_handlers(chr, chr->gcontext);
     }
     return FALSE;
 }

 static void pty_chr_rearm_timer(Chardev *chr, int ms)
 {
     PtyChardev *s = PTY_CHARDEV(chr);
     char *name;

     pty_chr_timer_cancel(s);
     name = g_strdup_printf("pty-timer-%s", chr->label);
     s->timer_src = qemu_chr_timeout_add_ms(chr, ms, pty_chr_timer, chr);
     g_source_set_name(s->timer_src, name);
     g_free(name);
 }

 static void pty_chr_update_read_handler(Chardev *chr)
 {
     PtyChardev *s = PTY_CHARDEV(chr);
     GPollFD pfd;
     int rc;
     QIOChannelFile *fioc = QIO_CHANNEL_FILE(s->ioc);

     pfd.fd = fioc->fd;
     pfd.events = G_IO_OUT;
     pfd.revents = 0;
     rc = RETRY_ON_EINTR(g_poll(&pfd, 1, 0));
     assert(rc >= 0);

     if (pfd.revents & G_IO_HUP) {
         pty_chr_state(chr, 0);
     } else {
         pty_chr_state(chr, 1);
     }
 }

 static int char_pty_chr_write(Chardev *chr, const uint8_t *buf, int len)
 {
     PtyChardev *s = PTY_CHARDEV(chr);
     GPollFD pfd;
     int rc;

     if (s->connected) {
         return io_channel_send(s->ioc, buf, len);
     }

     /*
      * The other side might already be re-connected, but the timer might
      * not have fired yet. So let's check here whether we can write again:
      */
     pfd.fd = QIO_CHANNEL_FILE(s->ioc)->fd;
     pfd.events = G_IO_OUT;
     pfd.revents = 0;
     rc = RETRY_ON_EINTR(g_poll(&pfd, 1, 0));
     g_assert(rc >= 0);
     if (!(pfd.revents & G_IO_HUP) && (pfd.revents & G_IO_OUT)) {
         io_channel_send(s->ioc, buf, len);
     }

     return len;
 }

 static GSource *pty_chr_add_watch(Chardev *chr, GIOCondition cond)
 {
     PtyChardev *s = PTY_CHARDEV(chr);
     if (!s->connected) {
         return NULL;
     }
     return qio_channel_create_watch(s->ioc, cond);
 }

 static int pty_chr_read_poll(void *opaque)
 {
     Chardev *chr = CHARDEV(opaque);
     PtyChardev *s = PTY_CHARDEV(opaque);

     s->read_bytes = qemu_chr_be_can_write(chr);
     return s->read_bytes;
 }

 static gboolean pty_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
 {
     Chardev *chr = CHARDEV(opaque);
     PtyChardev *s = PTY_CHARDEV(opaque);
     gsize len;
     uint8_t buf[CHR_READ_BUF_LEN];
     ssize_t ret;

     len = sizeof(buf);
     if (len > s->read_bytes) {
         len = s->read_bytes;
     }
     if (len == 0) {
         return TRUE;
     }
     ret = qio_channel_read(s->ioc, (char *)buf, len, NULL);
     if (ret <= 0) {
         pty_chr_state(chr, 0);
         return FALSE;
     } else {
         pty_chr_state(chr, 1);
         qemu_chr_be_write(chr, buf, ret);
     }
     return TRUE;
 }

 static void pty_chr_state(Chardev *chr, int connected)
 {
     PtyChardev *s = PTY_CHARDEV(chr);

     if (!connected) {
         remove_fd_in_watch(chr);
         s->connected = 0;
         /* (re-)connect poll interval for idle guests: once per second.
          * We check more frequently in case the guests sends data to
          * the virtual device linked to our pty. */
         pty_chr_rearm_timer(chr, 1000);
     } else {
         pty_chr_timer_cancel(s);
         if (!s->connected) {
             s->connected = 1;
             qemu_chr_be_event(chr, CHR_EVENT_OPENED);
         }
         if (!chr->gsource) {
             chr->gsource = io_add_watch_poll(chr, s->ioc,
                                                pty_chr_read_poll,
                                                pty_chr_read,
                                                chr, chr->gcontext);
         }
     }
 }

 static void char_pty_finalize(Object *obj)
 {
     Chardev *chr = CHARDEV(obj);
     PtyChardev *s = PTY_CHARDEV(obj);

     /* unlink symlink */
     if (s->path) {
         unlink(s->path);
         g_free(s->path);
     }

     pty_chr_state(chr, 0);
     object_unref(OBJECT(s->ioc));
     pty_chr_timer_cancel(s);
     qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
 }

 #if defined HAVE_PTY_H
 # include <pty.h>
 #elif defined CONFIG_BSD
 # include <termios.h>
 # if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
 #  include <libutil.h>
 # else
 #  include <util.h>
 # endif
 #elif defined CONFIG_SOLARIS
 # include <termios.h>
 # include <stropts.h>
 #else
 # include <termios.h>
 #endif

 #ifdef __sun__

 #if !defined(HAVE_OPENPTY)
 /* Once illumos has openpty(), this is going to be removed. */
 static int openpty(int *amaster, int *aslave, char *name,
                    struct termios *termp, struct winsize *winp)
 {
     const char *slave;
     int mfd = -1, sfd = -1;

     *amaster = *aslave = -1;

     mfd = open("/dev/ptmx", O_RDWR | O_NOCTTY);
     if (mfd < 0) {
         goto err;
     }

     if (grantpt(mfd) == -1 || unlockpt(mfd) == -1) {
         goto err;
     }

     if ((slave = ptsname(mfd)) == NULL) {
         goto err;
     }

     if ((sfd = open(slave, O_RDONLY | O_NOCTTY)) == -1) {
         goto err;
     }

     if (ioctl(sfd, I_PUSH, "ptem") == -1 ||
         (termp != NULL && tcgetattr(sfd, termp) < 0)) {
         goto err;
     }

     *amaster = mfd;
     *aslave = sfd;

     if (winp) {
         ioctl(sfd, TIOCSWINSZ, winp);
     }

     return 0;

 err:
     if (sfd != -1) {
         close(sfd);
     }
     close(mfd);
     return -1;
 }
 #endif

 static void cfmakeraw (struct termios *termios_p)
 {
     termios_p->c_iflag &=
         ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON);
     termios_p->c_oflag &= ~OPOST;
     termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
     termios_p->c_cflag &= ~(CSIZE | PARENB);
     termios_p->c_cflag |= CS8;

     termios_p->c_cc[VMIN] = 0;
     termios_p->c_cc[VTIME] = 0;
 }
 #endif

 /* like openpty() but also makes it raw; return master fd */
 static int qemu_openpty_raw(int *aslave, char *pty_name)
 {
     int amaster;
     struct termios tty;
 #if defined(__OpenBSD__) || defined(__DragonFly__)
     char pty_buf[PATH_MAX];
 #define q_ptsname(x) pty_buf
 #else
     char *pty_buf = NULL;
 #define q_ptsname(x) ptsname(x)
 #endif

     if (openpty(&amaster, aslave, pty_buf, NULL, NULL) < 0) {
         return -1;
     }

     /* Set raw attributes on the pty. */
     tcgetattr(*aslave, &tty);
     cfmakeraw(&tty);
     tcsetattr(*aslave, TCSAFLUSH, &tty);

     if (pty_name) {
         strcpy(pty_name, q_ptsname(amaster));
     }

     return amaster;
 }

 static void char_pty_open(Chardev *chr,
                           ChardevBackend *backend,
                           bool *be_opened,
                           Error **errp)
 {
     PtyChardev *s;
     int master_fd, slave_fd;
     char pty_name[PATH_MAX];
     char *name;
     char *path = backend->u.pty.data->path;

     master_fd = qemu_openpty_raw(&slave_fd, pty_name);
     if (master_fd < 0) {
         error_setg_errno(errp, errno, "Failed to create PTY");
         return;
     }

     close(slave_fd);
     if (!g_unix_set_fd_nonblocking(master_fd, true, NULL)) {
         error_setg_errno(errp, errno, "Failed to set FD nonblocking");
         return;
     }

     chr->filename = g_strdup_printf("pty:%s", pty_name);
     qemu_printf("char device redirected to %s (label %s)\n",
                 pty_name, chr->label);

     s = PTY_CHARDEV(chr);
     s->ioc = QIO_CHANNEL(qio_channel_file_new_fd(master_fd));
     name = g_strdup_printf("chardev-pty-%s", chr->label);
     qio_channel_set_name(s->ioc, name);
     g_free(name);
     s->timer_src = NULL;
     *be_opened = false;

     /* create symbolic link */
     if (path) {
         int res = symlink(pty_name, path);

         if (res != 0) {
             error_setg_errno(errp, errno, "Failed to create PTY symlink");
         } else {
             s->path = g_strdup(path);
         }
     }
 }

 static void char_pty_parse(QemuOpts *opts, ChardevBackend *backend,
                            Error **errp)
 {
     const char *path = qemu_opt_get(opts, "path");
     ChardevPty *pty;

     backend->type = CHARDEV_BACKEND_KIND_PTY;
     pty = backend->u.pty.data = g_new0(ChardevPty, 1);
     qemu_chr_parse_common(opts, qapi_ChardevPty_base(pty));
     pty->path = g_strdup(path);
 }

 static void char_pty_class_init(ObjectClass *oc, void *data)
 {
     ChardevClass *cc = CHARDEV_CLASS(oc);

     cc->parse = char_pty_parse;
     cc->open = char_pty_open;
     cc->chr_write = char_pty_chr_write;
     cc->chr_update_read_handler = pty_chr_update_read_handler;
     cc->chr_add_watch = pty_chr_add_watch;
 }

 static const TypeInfo char_pty_type_info = {
     .name = TYPE_CHARDEV_PTY,
     .parent = TYPE_CHARDEV,
     .instance_size = sizeof(PtyChardev),
     .instance_finalize = char_pty_finalize,
     .class_init = char_pty_class_init,
 };

 static void register_types(void)
 {
     type_register_static(&char_pty_type_info);
 }

 type_init(register_types);
	/*
	* QEMU System Emulator
	*
	* Copyright (c) 2003-2008 Fabrice Bellard
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/

	#include "qemu/osdep.h"
	#include "qapi/error.h"
	#include "chardev/char.h"
	#include "io/channel-file.h"
	#include "qemu/sockets.h"
	#include "qemu/error-report.h"
	#include "qemu/module.h"
	#include "qemu/option.h"
	#include "qemu/qemu-print.h"

	#include "chardev/char-io.h"
	#include "qom/object.h"

	struct PtyChardev {
	Chardev parent;
	QIOChannel *ioc;
	int read_bytes;

	int connected;
	GSource *timer_src;
	char *path;
	};
	typedef struct PtyChardev PtyChardev;

	DECLARE_INSTANCE_CHECKER(PtyChardev, PTY_CHARDEV,
	TYPE_CHARDEV_PTY)

	static void pty_chr_state(Chardev *chr, int connected);

	static void pty_chr_timer_cancel(PtyChardev *s)
	{
	if (s->timer_src) {
	g_source_destroy(s->timer_src);
	g_source_unref(s->timer_src);
	s->timer_src = NULL;
	}
	}

	static gboolean pty_chr_timer(gpointer opaque)
	{
	struct Chardev *chr = CHARDEV(opaque);
	PtyChardev *s = PTY_CHARDEV(opaque);

	pty_chr_timer_cancel(s);
	if (!s->connected) {
	/* Next poll ... */
	qemu_chr_be_update_read_handlers(chr, chr->gcontext);
	}
	return FALSE;
	}

	static void pty_chr_rearm_timer(Chardev *chr, int ms)
	{
	PtyChardev *s = PTY_CHARDEV(chr);
	char *name;

	pty_chr_timer_cancel(s);
	name = g_strdup_printf("pty-timer-%s", chr->label);
	s->timer_src = qemu_chr_timeout_add_ms(chr, ms, pty_chr_timer, chr);
	g_source_set_name(s->timer_src, name);
	g_free(name);
	}

	static void pty_chr_update_read_handler(Chardev *chr)
	{
	PtyChardev *s = PTY_CHARDEV(chr);
	GPollFD pfd;
	int rc;
	QIOChannelFile *fioc = QIO_CHANNEL_FILE(s->ioc);

	pfd.fd = fioc->fd;
	pfd.events = G_IO_OUT;
	pfd.revents = 0;
	rc = RETRY_ON_EINTR(g_poll(&pfd, 1, 0));
	assert(rc >= 0);

	if (pfd.revents & G_IO_HUP) {
	pty_chr_state(chr, 0);
	} else {
	pty_chr_state(chr, 1);
	}
	}

	static int char_pty_chr_write(Chardev chr, const uint8_t buf, int len)
	{
	PtyChardev *s = PTY_CHARDEV(chr);
	GPollFD pfd;
	int rc;

	if (s->connected) {
	return io_channel_send(s->ioc, buf, len);
	}

	/*
	* The other side might already be re-connected, but the timer might
	* not have fired yet. So let's check here whether we can write again:
	*/
	pfd.fd = QIO_CHANNEL_FILE(s->ioc)->fd;
	pfd.events = G_IO_OUT;
	pfd.revents = 0;
	rc = RETRY_ON_EINTR(g_poll(&pfd, 1, 0));
	g_assert(rc >= 0);
	if (!(pfd.revents & G_IO_HUP) && (pfd.revents & G_IO_OUT)) {
	io_channel_send(s->ioc, buf, len);
	}

	return len;
	}

	static GSource pty_chr_add_watch(Chardev chr, GIOCondition cond)
	{
	PtyChardev *s = PTY_CHARDEV(chr);
	if (!s->connected) {
	return NULL;
	}
	return qio_channel_create_watch(s->ioc, cond);
	}

	static int pty_chr_read_poll(void *opaque)
	{
	Chardev *chr = CHARDEV(opaque);
	PtyChardev *s = PTY_CHARDEV(opaque);

	s->read_bytes = qemu_chr_be_can_write(chr);
	return s->read_bytes;
	}

	static gboolean pty_chr_read(QIOChannel chan, GIOCondition cond, void opaque)
	{
	Chardev *chr = CHARDEV(opaque);
	PtyChardev *s = PTY_CHARDEV(opaque);
	gsize len;
	uint8_t buf[CHR_READ_BUF_LEN];
	ssize_t ret;

	len = sizeof(buf);
	if (len > s->read_bytes) {
	len = s->read_bytes;
	}
	if (len == 0) {
	return TRUE;
	}
	ret = qio_channel_read(s->ioc, (char *)buf, len, NULL);
	if (ret <= 0) {
	pty_chr_state(chr, 0);
	return FALSE;
	} else {
	pty_chr_state(chr, 1);
	qemu_chr_be_write(chr, buf, ret);
	}
	return TRUE;
	}

	static void pty_chr_state(Chardev *chr, int connected)
	{
	PtyChardev *s = PTY_CHARDEV(chr);

	if (!connected) {
	remove_fd_in_watch(chr);
	s->connected = 0;
	/* (re-)connect poll interval for idle guests: once per second.
	* We check more frequently in case the guests sends data to
	* the virtual device linked to our pty. */
	pty_chr_rearm_timer(chr, 1000);
	} else {
	pty_chr_timer_cancel(s);
	if (!s->connected) {
	s->connected = 1;
	qemu_chr_be_event(chr, CHR_EVENT_OPENED);
	}
	if (!chr->gsource) {
	chr->gsource = io_add_watch_poll(chr, s->ioc,
	pty_chr_read_poll,
	pty_chr_read,
	chr, chr->gcontext);
	}
	}
	}

	static void char_pty_finalize(Object *obj)
	{
	Chardev *chr = CHARDEV(obj);
	PtyChardev *s = PTY_CHARDEV(obj);

	/* unlink symlink */
	if (s->path) {
	unlink(s->path);
	g_free(s->path);
	}

	pty_chr_state(chr, 0);
	object_unref(OBJECT(s->ioc));
	pty_chr_timer_cancel(s);
	qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
	}

	#if defined HAVE_PTY_H
	# include <pty.h>
	#elif defined CONFIG_BSD
	# include <termios.h>
	# if defined(__FreeBSD__) \|\| defined(__FreeBSD_kernel__) \|\| defined(__DragonFly__)
	# include <libutil.h>
	# else
	# include <util.h>
	# endif
	#elif defined CONFIG_SOLARIS
	# include <termios.h>
	# include <stropts.h>
	#else
	# include <termios.h>
	#endif

	#ifdef __sun__

	#if !defined(HAVE_OPENPTY)
	/* Once illumos has openpty(), this is going to be removed. */
	static int openpty(int amaster, int aslave, char *name,
	struct termios termp, struct winsize winp)
	{
	const char *slave;
	int mfd = -1, sfd = -1;

	amaster = aslave = -1;

	mfd = open("/dev/ptmx", O_RDWR \| O_NOCTTY);
	if (mfd < 0) {
	goto err;
	}

	if (grantpt(mfd) == -1 \|\| unlockpt(mfd) == -1) {
	goto err;
	}

	if ((slave = ptsname(mfd)) == NULL) {
	goto err;
	}

	if ((sfd = open(slave, O_RDONLY \| O_NOCTTY)) == -1) {
	goto err;
	}

	if (ioctl(sfd, I_PUSH, "ptem") == -1 \|\|
	(termp != NULL && tcgetattr(sfd, termp) < 0)) {
	goto err;
	}

	*amaster = mfd;
	*aslave = sfd;

	if (winp) {
	ioctl(sfd, TIOCSWINSZ, winp);
	}

	return 0;

	err:
	if (sfd != -1) {
	close(sfd);
	}
	close(mfd);
	return -1;
	}
	#endif

	static void cfmakeraw (struct termios *termios_p)
	{
	termios_p->c_iflag &=
	~(IGNBRK \| BRKINT \| PARMRK \| ISTRIP \| INLCR \| IGNCR \| ICRNL \| IXON);
	termios_p->c_oflag &= ~OPOST;
	termios_p->c_lflag &= ~(ECHO \| ECHONL \| ICANON \| ISIG \| IEXTEN);
	termios_p->c_cflag &= ~(CSIZE \| PARENB);
	termios_p->c_cflag \|= CS8;

	termios_p->c_cc[VMIN] = 0;
	termios_p->c_cc[VTIME] = 0;
	}
	#endif

	/* like openpty() but also makes it raw; return master fd */
	static int qemu_openpty_raw(int aslave, char pty_name)
	{
	int amaster;
	struct termios tty;
	#if defined(__OpenBSD__) \|\| defined(__DragonFly__)
	char pty_buf[PATH_MAX];
	#define q_ptsname(x) pty_buf
	#else
	char *pty_buf = NULL;
	#define q_ptsname(x) ptsname(x)
	#endif

	if (openpty(&amaster, aslave, pty_buf, NULL, NULL) < 0) {
	return -1;
	}

	/* Set raw attributes on the pty. */
	tcgetattr(*aslave, &tty);
	cfmakeraw(&tty);
	tcsetattr(*aslave, TCSAFLUSH, &tty);

	if (pty_name) {
	strcpy(pty_name, q_ptsname(amaster));
	}

	return amaster;
	}

	static void char_pty_open(Chardev *chr,
	ChardevBackend *backend,
	bool *be_opened,
	Error **errp)
	{
	PtyChardev *s;
	int master_fd, slave_fd;
	char pty_name[PATH_MAX];
	char *name;
	char *path = backend->u.pty.data->path;

	master_fd = qemu_openpty_raw(&slave_fd, pty_name);
	if (master_fd < 0) {
	error_setg_errno(errp, errno, "Failed to create PTY");
	return;
	}

	close(slave_fd);
	if (!g_unix_set_fd_nonblocking(master_fd, true, NULL)) {
	error_setg_errno(errp, errno, "Failed to set FD nonblocking");
	return;
	}

	chr->filename = g_strdup_printf("pty:%s", pty_name);
	qemu_printf("char device redirected to %s (label %s)\n",
	pty_name, chr->label);

	s = PTY_CHARDEV(chr);
	s->ioc = QIO_CHANNEL(qio_channel_file_new_fd(master_fd));
	name = g_strdup_printf("chardev-pty-%s", chr->label);
	qio_channel_set_name(s->ioc, name);
	g_free(name);
	s->timer_src = NULL;
	*be_opened = false;

	/* create symbolic link */
	if (path) {
	int res = symlink(pty_name, path);

	if (res != 0) {
	error_setg_errno(errp, errno, "Failed to create PTY symlink");
	} else {
	s->path = g_strdup(path);
	}
	}
	}

	static void char_pty_parse(QemuOpts opts, ChardevBackend backend,
	Error **errp)
	{
	const char *path = qemu_opt_get(opts, "path");
	ChardevPty *pty;

	backend->type = CHARDEV_BACKEND_KIND_PTY;
	pty = backend->u.pty.data = g_new0(ChardevPty, 1);
	qemu_chr_parse_common(opts, qapi_ChardevPty_base(pty));
	pty->path = g_strdup(path);
	}

	static void char_pty_class_init(ObjectClass oc, void data)
	{
	ChardevClass *cc = CHARDEV_CLASS(oc);

	cc->parse = char_pty_parse;
	cc->open = char_pty_open;
	cc->chr_write = char_pty_chr_write;
	cc->chr_update_read_handler = pty_chr_update_read_handler;
	cc->chr_add_watch = pty_chr_add_watch;
	}

	static const TypeInfo char_pty_type_info = {
	.name = TYPE_CHARDEV_PTY,
	.parent = TYPE_CHARDEV,
	.instance_size = sizeof(PtyChardev),
	.instance_finalize = char_pty_finalize,
	.class_init = char_pty_class_init,
	};

	static void register_types(void)
	{
	type_register_static(&char_pty_type_info);
	}

	type_init(register_types);