[Intel-gfx] [PATCH i-g-t] lib/igt_kms.c: remove tests dependency on VT /dev/tty0

[Marc Herbert]

Required to run on any recent, freon-based and X11-free ChromeOS release.

Signed-off-by: Marc Herbert <marc.herbert at intel.com>
---
 lib/igt_kms.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index d0c3690..27cff86 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -299,12 +299,24 @@ int kmstest_get_pipe_from_crtc_id(int fd, int crtc_id)
 	return pfci.pipe;
 }
 
+static unsigned long orig_vt_mode = -1UL;
+
 static signed long set_vt_mode(unsigned long mode)
 {
 	int fd;
 	unsigned long prev_mode;
+	static const char TTY0[] = "/dev/tty0";
+
+	if (access(TTY0, F_OK)) {
+		/* errno message should be "No such file". Do not
+		   hardcode but ask strerror() in the very unlikely
+		   case something else happened. */
+		igt_warn("VT: %s: %s, cannot change its mode\n",
+			  TTY0, strerror(errno));
+		return orig_vt_mode;
+	}
 
-	fd = open("/dev/tty0", O_RDONLY);
+	fd = open(TTY0, O_RDONLY);
 	if (fd < 0)
 		return -errno;
 
@@ -323,8 +335,6 @@ err:
 	return -errno;
 }
 
-static unsigned long orig_vt_mode = -1UL;
-
 /**
  * kmstest_restore_vt_mode:
  *
@@ -363,6 +373,10 @@ void kmstest_set_vt_graphics_mode(void)
 	ret = set_vt_mode(KD_GRAPHICS);
 	igt_enable_exit_handler();
 
+	/* Return if set_vt_mode has successfully not changed anything */
+	if (ret == orig_vt_mode)
+		return;
+
 	igt_assert(ret >= 0);
 	orig_vt_mode = ret;
 
-- 
1.9.3