feedbackd: Support visual feedback via LEDs

Currently all LED feedbacks are infinite we can improve that
later on by using the 'repeat' attribute of the LED pattern
trigger.

src/fbd-udev.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2020 Purism SPC
+ * SPDX-License-Identifier: GPL-3.0+
+ * Author: Guido Günther <agx@sigxcpu.org>
+ *
+ */
+
+#define G_LOG_DOMAIN "fbd-udev"
+
+#include "fbd-udev.h"
+
+#include <gio/gio.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+
+gboolean
+fbd_udev_set_sysfs_path_attr_as_string (GUdevDevice *dev, const gchar *attr,
+                                        const gchar *s, GError **err)
+{
+  gint fd;
+  int len;
+  g_autofree gchar *path = g_strjoin ("/", g_udev_device_get_sysfs_path (dev),
+                                      attr, NULL);
+
+  fd = open (path, O_WRONLY|O_TRUNC, 0666);
+  if (fd < 0) {
+    g_set_error (err, G_IO_ERROR, G_IO_ERROR_FAILED, "Failed to open %s: %s",
+                 path, strerror (errno));
+    return FALSE;
+  }
+
+  len = strlen (s);
+  if (write (fd, s, len) < 0) {
+    g_set_error (err, G_IO_ERROR, G_IO_ERROR_FAILED, "Failed to write %s to %s: %s",
+                 s, path, strerror (errno));
+    close (fd);
+    return FALSE;
+  }
+
+  if (close (fd) < 0) {
+    g_set_error (err, G_IO_ERROR, G_IO_ERROR_FAILED, "Failed to close %s: %s",
+                 path, strerror (errno));
+    return FALSE;
+  }
+
+  return TRUE;
+}
+
+gboolean
+fbd_udev_set_sysfs_path_attr_as_int (GUdevDevice *dev, const gchar *attr,
+                                     gint val, GError **err)
+{
+  gint fd;
+  int len;
+  g_autofree gchar *s = NULL;
+
+  g_autofree gchar *path = g_strjoin ("/", g_udev_device_get_sysfs_path (dev),
+                                      attr, NULL);
+
+  fd = open (path, O_WRONLY|O_TRUNC, 0666);
+  if (fd < 0) {
+    g_set_error (err, G_IO_ERROR, G_IO_ERROR_FAILED, "Failed to open %s: %s",
+                 path, strerror (errno));
+    return FALSE;
+  }
+
+  s = g_strdup_printf ("%d", val);
+  len = strlen (s);
+  if (write (fd, s, len) < len) {
+    g_set_error (err, G_IO_ERROR, G_IO_ERROR_FAILED, "Failed to write %s: %s",
+                 path, strerror (errno));
+    close (fd);
+    return FALSE;
+  }
+
+  if (close (fd) < 0) {
+    g_set_error (err, G_IO_ERROR, G_IO_ERROR_FAILED, "Failed to close %s: %s",
+                 path, strerror (errno));
+    return FALSE;
+  }
+
+  return TRUE;
+}