lib/igt_debugfs: Add helper for detecting debugfs files

Add a helper that can be used with, for ex, igt_require() so that tests
can be skipped if the kernel is too old.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Petri Latvala <petri.latvala@intel.com>

2 files changed, 22 insertions, 0 deletions

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index dd6f2995c..7211c4102 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -308,6 +308,27 @@ int igt_debugfs_open(int device, const char *filename, int mode)
 }
 
 /**
+ * igt_debugfs_exists:
+ * @device: the drm device file fd
+ * @filename: file name
+ * @mode: mode bits as used by open()
+ *
+ * Test that the specified debugfs file exists and can be opened with the
+ * requested mode.
+ */
+bool igt_debugfs_exists(int device, const char *filename, int mode)
+{
+	int fd = igt_debugfs_open(device, filename, mode);
+
+	if (fd >= 0) {
+		close(fd);
+		return true;
+	}
+
+	return false;
+}
+
+/**
  * igt_debugfs_simple_read:
  * @filename: file name
  * @buf: buffer where the contents will be stored, allocated by the caller
diff --git a/lib/igt_debugfs.h b/lib/igt_debugfs.h
index b48676815..37e85067b 100644
--- a/lib/igt_debugfs.h
+++ b/lib/igt_debugfs.h
@@ -39,6 +39,7 @@ int igt_debugfs_connector_dir(int device, char *conn_name, int mode);
 int igt_debugfs_pipe_dir(int device, int pipe, int mode);
 
 int igt_debugfs_open(int fd, const char *filename, int mode);
+bool igt_debugfs_exists(int fd, const char *filename, int mode);
 void __igt_debugfs_read(int fd, const char *filename, char *buf, int size);
 void __igt_debugfs_write(int fd, const char *filename, const char *buf, int size);
 int igt_debugfs_simple_read(int dir, const char *filename, char *buf, int size);