pty: set XDG_VTNR if requested by caller

A caller can now pass a VT-num to the PTY which will get set as XDG_VTNR
in the environment of new childs.

This can be used to tell systemd-logind to associate the session with
the correct VT. But note that this still cannot overwrite VT-associations
if the pty is created from within an existing session.

Reported-by: Thomas Hebb
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

2 files changed, 24 insertions, 2 deletions

diff --git a/src/pty.c b/src/pty.c
index 3e17512..3494104 100644
--- a/src/pty.c
+++ b/src/pty.c
@@ -63,6 +63,7 @@ struct kmscon_pty {
 	char *colorterm;
 	char **argv;
 	char *seat;
+	char *vtnr;
 	bool env_reset;
 };
 
@@ -119,6 +120,7 @@ void kmscon_pty_unref(struct kmscon_pty *pty)
 
 	log_debug("free pty object");
 	kmscon_pty_close(pty);
+	free(pty->vtnr);
 	free(pty->seat);
 	free(pty->argv);
 	free(pty->colorterm);
@@ -193,6 +195,23 @@ int kmscon_pty_set_seat(struct kmscon_pty *pty, const char *seat)
 	return 0;
 }
 
+int kmscon_pty_set_vtnr(struct kmscon_pty *pty, unsigned int vtnr)
+{
+	char *t;
+	int ret;
+
+	if (!pty)
+		return -EINVAL;
+
+	ret = asprintf(&t, "%u", vtnr);
+	if (ret < 0)
+		return -ENOMEM;
+	free(pty->vtnr);
+	pty->vtnr = t;
+
+	return 0;
+}
+
 void kmscon_pty_set_env_reset(struct kmscon_pty *pty, bool do_reset)
 {
 	if (!pty)
@@ -224,7 +243,7 @@ static bool pty_is_open(struct kmscon_pty *pty)
 
 static void __attribute__((noreturn))
 exec_child(const char *term, const char *colorterm, char **argv,
-	   const char *seat, bool env_reset)
+	   const char *seat, const char *vtnr, bool env_reset)
 {
 	char **env;
 	char **def_argv;
@@ -255,6 +274,8 @@ exec_child(const char *term, const char *colorterm, char **argv,
 		setenv("COLORTERM", colorterm, 1);
 	if (seat)
 		setenv("XDG_SEAT", seat, 1);
+	if (vtnr)
+		setenv("XDG_VTNR", vtnr, 1);
 
 	execve(argv[0], argv, environ);
 
@@ -376,7 +397,7 @@ static int pty_spawn(struct kmscon_pty *pty, int master,
 	case 0:
 		setup_child(master, &ws);
 		exec_child(pty->term, pty->colorterm, pty->argv, pty->seat,
-			   pty->env_reset);
+			   pty->vtnr, pty->env_reset);
 		exit(EXIT_FAILURE);
 	default:
 		log_debug("forking child %d", pid);
diff --git a/src/pty.h b/src/pty.h
index 67dc124..e5e051a 100644
--- a/src/pty.h
+++ b/src/pty.h
@@ -58,6 +58,7 @@ int kmscon_pty_set_term(struct kmscon_pty *pty, const char *term);
 int kmscon_pty_set_colorterm(struct kmscon_pty *pty, const char *colorterm);
 int kmscon_pty_set_argv(struct kmscon_pty *pty, char **argv);
 int kmscon_pty_set_seat(struct kmscon_pty *pty, const char *seat);
+int kmscon_pty_set_vtnr(struct kmscon_pty *pty, unsigned int vtnr);
 void kmscon_pty_set_env_reset(struct kmscon_pty *pty, bool do_reset);
 
 int kmscon_pty_get_fd(struct kmscon_pty *pty);