1 files changed, 68 insertions, 0 deletions
diff --git a/src/luxinit.c b/src/luxinit.c
new file mode 100644
index 0000000..ae25925
--- /dev/null
+++ b/src/luxinit.c
@@ -0,0 +1,68 @@
+/*
+ * BSD Zero Clause License
+ *
+ * Copyright (c) 2022 Thomas Voss
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+
+#include <dirent.h>
+#include <fcntl.h>
+
+#include "lux.h"
+
+static int getdir(void);
+
+int
+luxinit(lux_t *disp)
+{
+	/* Set the default values for the luxdisp struct.  We want to be as lazy
+	 * as possible, so we don't bother with __bstream and __max yet.  We do
+	 * need __dirfd though.
+	 */
+	*disp = (lux_t) {
+		.__bstream = NULL,
+		.__max     = -1,
+		.__dirfd   = getdir()
+	};
+	return disp->__dirfd;
+}
+
+int
+getdir(void)
+{
+	int fd, dfd;
+	struct dirent *dp;
+	DIR *dir;
+
+	/* To get the file descriptor for the directory where all the brightness
+	 * files are located, we first need to open LUX_BACKLIGHT_DIR which is
+	 * the directory where the backlight directories are located.  Then we
+	 * need to get a DIR* of that directory and get the 3rd entry.  We need
+	 * the third because the fist and second are the . and .. folders.
+	 * Finally we open the folder so that we have a file descriptor we can
+	 * return.
+	 */
+	if ((dfd = open(LUX_BACKLIGHT_DIR, O_RDONLY)) == -1
+			|| (dir = fdopendir(dfd)) == NULL)
+		return -1;
+	if ((dp = readdir(dir)) == NULL
+			|| (dp = readdir(dir)) == NULL
+			|| (dp = readdir(dir)) == NULL
+			|| (fd = openat(dfd, dp->d_name, LUX_GDIR_FLAGS)) == -1)
+		fd = -1;
+
+	closedir(dir);
+	return fd;
+}