pty: support POLLHUP

kernel-src/include/kernel/tty.h

@@ -34,6 +34,8 @@ typedef struct {
 	vnode_t *mastervnode;
 	spinlock_t sessionlock;
 	struct proc_t *session;
+	size_t opened;
+	bool has_been_opened;
 } tty_t;
 
 void tty_init();
@@ -41,5 +43,6 @@ tty_t *tty_create(char *name, ttydevicewritefn_t writefn, ttyinactivefn_t inacti
 void tty_process(tty_t *tty, char c);
 void tty_unregister(tty_t *tty);
 int tty_ioctl(tty_t *tty, unsigned long req, void *arg, int *result, cred_t *cred);
+size_t tty_opened(tty_t *tty);
 
 #endif

kernel-src/io/pty.c

@@ -87,12 +87,6 @@ static int hup_check(void *_pty) {
 	return pty->hangup;
 }
 
-static void inactivepty(void *_pty) {
-	pty_t *pty = _pty;
-	freeptyminor(pty->minor);
-	freepty(pty);
-}
-
 static int isatty(int minor) {
 	return 0;
 }
@@ -119,9 +113,13 @@ static int close(int minor, int flags) {
 	return 0;
 }
 
+// TODO: also signal POLLHUP on tty close
 static int internalpoll(pty_t *pty, polldata_t *data, int events) {
 	int revents = 0;
 
+	if (pty->tty->has_been_opened && tty_opened(pty->tty) == 0)
+		revents |= POLLHUP;
+
 	if (events & POLLOUT)
 		revents |= POLLOUT;
 
@@ -230,6 +228,15 @@ static int write(int minor, iovec_iterator_t *iovec_iterator, size_t size, uintm
 	return 0;
 }
 
+static void inactive(int minor) {
+	pty_t *pty = ptyget(minor);
+	if (pty == NULL)
+		return;
+
+	freeptyminor(pty->minor);
+	freepty(pty);
+}
+
 static devops_t devops = {
 	.open = open,
 	.isatty = isatty,
@@ -237,7 +244,8 @@ static devops_t devops = {
 	.close = close,
 	.poll = poll,
 	.read = read,
-	.ioctl = ioctl
+	.ioctl = ioctl,
+	.inactive = inactive
 };
 
 static int open(int oldminor, vnode_t **vnode, int flags) {
@@ -276,7 +284,7 @@ static int open(int oldminor, vnode_t **vnode, int flags) {
 	// create a pairing slave device
 
 	snprintf(tmpname, 20, "pts/%d", newminor);
-	pty->tty = tty_create(tmpname, writetopty, inactivepty, NULL, hup_check, pty);
+	pty->tty = tty_create(tmpname, writetopty, NULL, NULL, hup_check, pty);
 	if (pty->tty == NULL) {
 		VOP_RELEASE(pty->mastervnode);
 		return ENOMEM;

kernel-src/io/tty.c

@@ -426,7 +426,10 @@ static int open(int minor, vnode_t **vnode, int flags) {
 		}
 
 		VOP_RELEASE(*vnode);
+		__atomic_fetch_add(&ctty->opened, 1, __ATOMIC_SEQ_CST);
+		ctty->has_been_opened = true;
 		*vnode = (vnode_t *)(ctty->mastervnode);
+		return 0;
 	} else if (tty == NULL) {
 		return ENODEV;
 	} else if ((flags & V_FFLAGS_NOCTTY) == 0) {
@@ -434,6 +437,18 @@ static int open(int minor, vnode_t **vnode, int flags) {
 		jobctl_setctty(current_thread()->proc, tty, false);
 	}
 
+	__atomic_fetch_add(&tty->opened, 1, __ATOMIC_SEQ_CST);
+	tty->has_been_opened = true;
+	return 0;
+}
+
+static int close(int minor, int flags) {
+	tty_t *tty = ttyget(minor);
+	if (tty == NULL)
+		return ENODEV;
+
+	int count = __atomic_fetch_sub(&tty->opened, 1, __ATOMIC_SEQ_CST);
+	__assert(count != 0);
 	return 0;
 }
 
@@ -484,6 +499,7 @@ static devops_t devops = {
 	.ioctl = ioctl,
 	.isatty = isatty,
 	.open = open,
+	.close = close,
 	.inactive = inactive
 };
 
@@ -574,6 +590,9 @@ void tty_unregister(tty_t *tty) {
 	}
 }
 
+size_t tty_opened(tty_t *tty) {
+	return __atomic_load_n(&tty->opened, __ATOMIC_SEQ_CST);
+}
 
 void tty_init() {
 	__assert(devfs_register(&devops, "tty", V_TYPE_CHDEV, DEV_MAJOR_TTY, CONTROLLING_TTY_MINOR, 0666, NULL) == 0);