tty: extra hang up checks

kernel-src/include/kernel/tty.h

@@ -12,6 +12,7 @@
 
 typedef size_t (*ttydevicewritefn_t)(void *internal, char *str, size_t size);
 typedef void (*ttyinactivefn_t)(void *internal);
+typedef int (*tty_hup_check_t)(void *internal);
 typedef void (*tty_termios_callback_t)(void *internal, termios_t *termios);
 
 typedef struct {
@@ -27,6 +28,7 @@ typedef struct {
 	ttydevicewritefn_t writetodevice;
 	ttyinactivefn_t inactivedevice;
 	tty_termios_callback_t termios_callback;
+	tty_hup_check_t hup_check;
 	int minor;
 	winsize_t winsize;
 	vnode_t *mastervnode;
@@ -35,7 +37,7 @@ typedef struct {
 } tty_t;
 
 void tty_init();
-tty_t *tty_create(char *name, ttydevicewritefn_t writefn, ttyinactivefn_t inactivefn, tty_termios_callback_t termios_callback, void *internal);
+tty_t *tty_create(char *name, ttydevicewritefn_t writefn, ttyinactivefn_t inactivefn, tty_termios_callback_t termios_callback, tty_hup_check_t hup_check, void *internal);
 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);

kernel-src/io/console.c

@@ -115,7 +115,7 @@ void console_init() {
 	__assert(thread);
 	sched_queue(thread);
 
-	tty = tty_create("console", console_ttywrite, NULL, NULL, NULL);
+	tty = tty_create("console", console_ttywrite, NULL, NULL, NULL, NULL);
 	__assert(tty);
 
 	size_t x, y, fbx, fby;

kernel-src/io/pty.c

@@ -81,6 +81,12 @@ static size_t writetopty(void *_pty, char *data, size_t size) {
 	return written;
 }
 
+// TODO: signal hup to the tty
+static int hup_check(void *_pty) {
+	pty_t *pty = _pty;
+	return pty->hangup;
+}
+
 static void inactivepty(void *_pty) {
 	pty_t *pty = _pty;
 	freeptyminor(pty->minor);
@@ -186,6 +192,7 @@ static int poll(int minor, polldata_t *data, int events) {
 	return revents;
 }
 #define TIOCGPTN 0x80045430
+#define TIOCSPTLCK 0x13376167
 static int ioctl(int minor, unsigned long request, void *_arg, int *result, cred_t *cred) {
 	pty_t *pty = ptyget(minor);
 	if (pty == NULL)
@@ -195,6 +202,9 @@ static int ioctl(int minor, unsigned long request, void *_arg, int *result, cred
 		case TIOCGPTN: {
 			return USERCOPY_POSSIBLY_TO_USER(_arg, &pty->minor, sizeof(int));
 		}
+		case TIOCSPTLCK: {
+			break; // no-op
+		}
 		default:
 			return tty_ioctl(pty->tty, request, _arg, result, cred);
 	}
@@ -266,7 +276,7 @@ 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, pty);
+	pty->tty = tty_create(tmpname, writetopty, inactivepty, NULL, hup_check, pty);
 	if (pty->tty == NULL) {
 		VOP_RELEASE(pty->mastervnode);
 		return ENOMEM;

kernel-src/io/serial/pc_com.c

@@ -266,7 +266,7 @@ static uacpi_iteration_decision init_com(void *, uacpi_namespace_node *node, uns
 	char tty_name[10];
 	snprintf(tty_name, 10, "com%d", pc_com->id);
 
-	pc_com->tty = tty_create(tty_name, write_tty, NULL, termios_callback, pc_com);
+	pc_com->tty = tty_create(tty_name, write_tty, NULL, termios_callback, NULL, pc_com);
 	if (pc_com->tty == NULL) {
 		printf("%s: failed to create tty\n", tty_name);
 		return UACPI_ITERATION_DECISION_NEXT_PEER;

kernel-src/io/tty.c

@@ -168,6 +168,9 @@ static int internalpoll(tty_t *tty, polldata_t *data, int events) {
 
 	MUTEX_ACQUIRE(&tty->readmutex);
 
+	if (tty->hup_check && tty->hup_check(tty->deviceinternal))
+		revents |= POLLHUP | (events & POLLIN);
+
 	if ((events & POLLIN) && RINGBUFFER_DATACOUNT(&tty->readbuffer))
 		revents |= POLLIN;
 
@@ -484,7 +487,7 @@ static devops_t devops = {
 	.inactive = inactive
 };
 
-tty_t *tty_create(char *name, ttydevicewritefn_t writefn, ttyinactivefn_t inactivefn, tty_termios_callback_t termios_callback, void *internal) {
+tty_t *tty_create(char *name, ttydevicewritefn_t writefn, ttyinactivefn_t inactivefn, tty_termios_callback_t termios_callback, tty_hup_check_t hup_check, void *internal) {
 	tty_t *tty = alloc(sizeof(tty_t));
 	if (tty == NULL)
 		return NULL;

kernel-src/sys/syscalls/ioctl.c

@@ -8,7 +8,10 @@ syscallret_t syscall_ioctl(context_t *, int fd, unsigned long request, void *arg
 		.ret = -1
 	};
 
-	if (IS_USER_ADDRESS(arg) == false) {
+	// arg could be null for, say, an ioctl that does not pass an argument
+	// this is safe as any accesses on ioctls are done through user copy, which
+	// returns EFAULT on a null access
+	if (arg != NULL && IS_USER_ADDRESS(arg) == false) {
 		ret.errno = EFAULT;
 		return ret;
 	}