From 53ad90da0f23da71a154c2b1a7783674e6adebf3 Mon Sep 17 00:00:00 2001
From: David Herrmann <dh.herrmann@googlemail.com>
Date: Sat, 1 Dec 2012 15:25:37 +0100
Subject: [PATCH] uterm: vt: use real VTs on all seats if available

If there is already a kmscon instance running that provides fake-VTs, then
lets use it. This allows stacking kmscon processes and is very useful for
debugging.

Also other applications that use uterm can now run inside of kmscon
without any other special configuration.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
---
 src/uterm.h    |  2 +-
 src/uterm_vt.c | 60 +++++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 50 insertions(+), 12 deletions(-)

diff --git a/src/uterm.h b/src/uterm.h
index ea326ef..475078a 100644
--- a/src/uterm.h
+++ b/src/uterm.h
@@ -353,7 +353,7 @@ int uterm_vt_master_deactivate_all(struct uterm_vt_master *vtm);
 
 int uterm_vt_allocate(struct uterm_vt_master *vt, struct uterm_vt **out,
 		      const char *seat, struct uterm_input *input,
-		      const char *vt_for_seat0, uterm_vt_cb cb, void *data);
+		      const char *vt_name, uterm_vt_cb cb, void *data);
 void uterm_vt_deallocate(struct uterm_vt *vt);
 void uterm_vt_ref(struct uterm_vt *vt);
 void uterm_vt_unref(struct uterm_vt *vt);
diff --git a/src/uterm_vt.c b/src/uterm_vt.c
index 382b1b8..5390f6d 100644
--- a/src/uterm_vt.c
+++ b/src/uterm_vt.c
@@ -78,7 +78,6 @@ struct uterm_vt_master {
 	unsigned long ref;
 	struct ev_eloop *eloop;
 
-	bool vt_support;
 	struct shl_dlist vts;
 };
 
@@ -313,7 +312,7 @@ static int open_tty(const char *dev, int *tty_fd, int *tty_num)
 	return 0;
 }
 
-static int real_open(struct uterm_vt *vt, const char *vt_for_seat0)
+static int real_open(struct uterm_vt *vt, const char *vt_name)
 {
 	struct vt_mode mode;
 	struct vt_stat vts;
@@ -321,7 +320,7 @@ static int real_open(struct uterm_vt *vt, const char *vt_for_seat0)
 
 	log_debug("open vt %p", vt);
 
-	ret = open_tty(vt_for_seat0, &vt->real_fd, &vt->real_num);
+	ret = open_tty(vt_name, &vt->real_fd, &vt->real_num);
 	if (ret)
 		return ret;
 
@@ -674,7 +673,7 @@ static void fake_input(struct uterm_vt *vt, struct uterm_input_event *ev)
 	}
 }
 
-static int fake_open(struct uterm_vt *vt, const char *vt_for_seat0)
+static int fake_open(struct uterm_vt *vt)
 {
 	uterm_input_wake_up(vt->input);
 	return 0;
@@ -738,16 +737,47 @@ static void vt_sigusr2(struct ev_eloop *eloop, struct signalfd_siginfo *info,
 		real_sig_leave(vt, info);
 }
 
+static int seat_find_vt(const char *seat, char **out)
+{
+	static const char def_vt[] = "/dev/tty0";
+	char *vt;
+	int ret;
+
+	ret = asprintf(&vt, "/dev/ttyF%s", seat);
+	if (ret < 0)
+		return -ENOMEM;
+
+	if (!access(vt, F_OK)) {
+		log_debug("using fake-VT %s", vt);
+		*out = vt;
+		return 0;
+	}
+
+	free(vt);
+
+	if (!strcmp(seat, "seat0") && !access(def_vt, F_OK)) {
+		vt = strdup(def_vt);
+		if (!vt)
+			return -ENOMEM;
+		*out = vt;
+		return 0;
+	}
+
+	*out = NULL;
+	return 0;
+}
+
 int uterm_vt_allocate(struct uterm_vt_master *vtm,
 		      struct uterm_vt **out,
 		      const char *seat,
 		      struct uterm_input *input,
-		      const char *vt_for_seat0,
+		      const char *vt_name,
 		      uterm_vt_cb cb,
 		      void *data)
 {
 	struct uterm_vt *vt;
 	int ret;
+	char *path;
 
 	if (!vtm || !out)
 		return -EINVAL;
@@ -780,14 +810,23 @@ int uterm_vt_allocate(struct uterm_vt_master *vtm,
 	if (ret)
 		goto err_sig2;
 
-	if (!strcmp(seat, "seat0") && vtm->vt_support) {
-		vt->mode = UTERM_VT_REAL;
-		ret = real_open(vt, vt_for_seat0);
+	if (!vt_name) {
+		ret = seat_find_vt(seat, &path);
+		if (ret)
+			goto err_input;
 	} else {
-		vt->mode = UTERM_VT_FAKE;
-		ret = fake_open(vt, vt_for_seat0);
+		path = NULL;
 	}
 
+	if (vt_name || path) {
+		vt->mode = UTERM_VT_REAL;
+		ret = real_open(vt, vt_name ? vt_name : path);
+	} else {
+		vt->mode = UTERM_VT_FAKE;
+		ret = fake_open(vt);
+	}
+
+	free(path);
 	if (ret)
 		goto err_input;
 
@@ -888,7 +927,6 @@ int uterm_vt_master_new(struct uterm_vt_master **out,
 	vtm->ref = 1;
 	vtm->eloop = eloop;
 	shl_dlist_init(&vtm->vts);
-	vtm->vt_support = !access("/dev/tty0", F_OK);
 
 	ev_eloop_ref(vtm->eloop);
 	*out = vtm;