Don't attempt to open() the tty path, rely on the client sending its stdin fd

with imsg and fatal if it doesn't, then set the FD_CLOEXEC flag in tty_init
instead of tty_open to prevent them leaking into child processes if any are
created between the two calls.

This bumps the protocol version, so the tmux server should be killed before
upgrading.

4 files changed, 39 insertions, 43 deletions

diff --git a/client.c b/client.c
index 05d5b606..ee3bba50 100644
--- a/client.c
+++ b/client.c
@@ -45,7 +45,7 @@ client_init(char *path, struct client_ctx *cctx, int cmdflags, int flags)
 	struct winsize			ws;
 	size_t				size;
 	int				fd, fd2, mode;
-	char			       *name, *term;
+	char			       *term;
 	char		 		rpathbuf[MAXPATHLEN];
 
 	if (realpath(path, rpathbuf) == NULL)
@@ -113,13 +113,8 @@ server_started:
 				*data.term = '\0';
 		}
 
-		*data.tty = '\0';
-		if ((name = ttyname(STDIN_FILENO)) == NULL)
-			fatal("ttyname failed");
-		if (strlcpy(data.tty, name, sizeof data.tty) >= sizeof data.tty)
-			fatalx("ttyname failed");
-
-		fd2 = dup(STDIN_FILENO);
+		if ((fd2 = dup(STDIN_FILENO)) == -1)
+			fatal("dup failed");
 		imsg_compose(&cctx->ibuf, MSG_IDENTIFY,
 		    PROTOCOL_VERSION, -1, fd2, &data, sizeof data);
 	}
diff --git a/server-msg.c b/server-msg.c
index cb5dbf06..cf0f346c 100644
--- a/server-msg.c
+++ b/server-msg.c
@@ -74,6 +74,8 @@ server_msg_dispatch(struct client *c)
 		case MSG_IDENTIFY:
 			if (datalen != sizeof identifydata)
 				fatalx("bad MSG_IDENTIFY size");
+			if (imsg.fd == -1)
+				fatalx("MSG_IDENTIFY missing fd");
 			memcpy(&identifydata, imsg.data, sizeof identifydata);
 
 			server_msg_identify(c, &identifydata, imsg.fd);
@@ -243,21 +245,13 @@ error:
 void
 server_msg_identify(struct client *c, struct msg_identify_data *data, int fd)
 {
-	c->tty.sx = data->sx;
-	if (c->tty.sx == 0)
-		c->tty.sx = 80;
-	c->tty.sy = data->sy;
-	if (c->tty.sy == 0)
-		c->tty.sy = 24;
-
 	c->cwd = NULL;
 	data->cwd[(sizeof data->cwd) - 1] = '\0';
 	if (*data->cwd != '\0')
 		c->cwd = xstrdup(data->cwd);
 
-	data->tty[(sizeof data->tty) - 1] = '\0';
 	data->term[(sizeof data->term) - 1] = '\0';
-	tty_init(&c->tty, fd, data->tty, data->term);
+	tty_init(&c->tty, fd, data->term);
 	if (data->flags & IDENTIFY_UTF8)
 		c->tty.flags |= TTY_UTF8;
 	if (data->flags & IDENTIFY_256COLOURS)
@@ -267,6 +261,13 @@ server_msg_identify(struct client *c, struct msg_identify_data *data, int fd)
 	if (data->flags & IDENTIFY_HASDEFAULTS)
 		c->tty.term_flags |= TERM_HASDEFAULTS;
 
+	c->tty.sx = data->sx;
+	if (c->tty.sx == 0)
+		c->tty.sx = 80;
+	c->tty.sy = data->sy;
+	if (c->tty.sy == 0)
+		c->tty.sy = 24;
+
 	c->flags |= CLIENT_TERMINAL;
 }
 
diff --git a/tmux.h b/tmux.h
index 0ffb0b53..bdaf5f6e 100644
--- a/tmux.h
+++ b/tmux.h
@@ -19,7 +19,7 @@
 #ifndef TMUX_H
 #define TMUX_H
 
-#define PROTOCOL_VERSION 1
+#define PROTOCOL_VERSION 2
 
 #include <sys/param.h>
 #include <sys/time.h>
@@ -328,8 +328,6 @@ struct msg_command_data {
 };
 
 struct msg_identify_data {
-	char		tty[TTY_NAME_MAX];
-
 	char		cwd[MAXPATHLEN];
 
 	char		term[TERMINAL_LENGTH];
@@ -1200,7 +1198,7 @@ void	tty_putcode2(struct tty *, enum tty_code_code, int, int);
 void	tty_puts(struct tty *, const char *);
 void	tty_putc(struct tty *, u_char);
 void	tty_pututf8(struct tty *, const struct grid_utf8 *);
-void	tty_init(struct tty *, int, char *, char *);
+void	tty_init(struct tty *, int, char *);
 void	tty_start_tty(struct tty *);
 void	tty_stop_tty(struct tty *);
 void	tty_detect_utf8(struct tty *);
diff --git a/tty.c b/tty.c
index b0810219..574e9a7b 100644
--- a/tty.c
+++ b/tty.c
@@ -44,16 +44,31 @@ void	tty_cell(struct tty *,
     	    const struct grid_cell *, const struct grid_utf8 *);
 
 void
-tty_init(struct tty *tty, int fd, char *path, char *term)
+tty_init(struct tty *tty, int fd, char *term)
 {
-	tty->path = xstrdup(path);
-	tty->fd = fd;
+	int	 mode;
+	char	*path;
+
+	memset(tty, 0, sizeof *tty);
 	tty->log_fd = -1;
 
 	if (term == NULL || *term == '\0')
 		tty->termname = xstrdup("unknown");
 	else
 		tty->termname = xstrdup(term);
+
+	if ((mode = fcntl(fd, F_GETFL)) == -1)
+		fatal("fcntl failed");
+	if (fcntl(fd, F_SETFL, mode|O_NONBLOCK) == -1)
+		fatal("fcntl failed");
+	if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
+		fatal("fcntl failed");
+	tty->fd = fd;
+
+	if ((path = ttyname(fd)) == NULL)
+		fatalx("ttyname failed");
+	tty->path = xstrdup(path);
+
 	tty->flags = 0;
 	tty->term_flags = 0;
 }
@@ -61,28 +76,15 @@ tty_init(struct tty *tty, int fd, char *path, char *term)
 int
 tty_open(struct tty *tty, const char *overrides, char **cause)
 {
-	int	mode;
+	int	fd;
 
-	if (tty->fd == -1) {
-		tty->fd = open(tty->path, O_RDWR|O_NONBLOCK);
-		if (tty->fd == -1) {
-			xasprintf(cause, "%s: %s", tty->path, strerror(errno));
-			return (-1);
-		}
+	if (debug_level > 3) {
+		fd = open("tmux.out", O_WRONLY|O_CREAT|O_TRUNC, 0644);
+		if (fd != -1 && fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
+			fatal("fcntl failed");
+		tty->log_fd = fd;
 	}
 
-	if ((mode = fcntl(tty->fd, F_GETFL)) == -1)
-		fatal("fcntl failed");
-	if (fcntl(tty->fd, F_SETFL, mode|O_NONBLOCK) == -1)
-		fatal("fcntl failed");
-	if (fcntl(tty->fd, F_SETFD, FD_CLOEXEC) == -1)
-		fatal("fcntl failed");
-
-	if (debug_level > 3)
-		tty->log_fd = open("tmux.out", O_WRONLY|O_CREAT|O_TRUNC, 0644);
-	else
-		tty->log_fd = -1;
-
 	tty->term = tty_term_find(tty->termname, tty->fd, overrides, cause);
 	if (tty->term == NULL) {
 		tty_close(tty);