From c8336345e553f0bea818312d5109339cd8dd8754 Mon Sep 17 00:00:00 2001
From: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Date: Sun, 9 Feb 2020 12:20:53 +0900
Subject: [PATCH] timer: add global method to get sysname for ALSA Timer

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 src/timer/alsatimer.map |  2 ++
 src/timer/query.c       | 60 +++++++++++++++++++++++++++++++++++++++++
 src/timer/query.h       |  2 ++
 3 files changed, 64 insertions(+)

diff --git a/src/timer/alsatimer.map b/src/timer/alsatimer.map
index 9fd4420..5051462 100644
--- a/src/timer/alsatimer.map
+++ b/src/timer/alsatimer.map
@@ -6,6 +6,8 @@ ALSA_GOBJECT_0_0_0 {
     "alsatimer_device_info_flag_get_type";
     "alsatimer_instance_param_flag_get_type";
     "alsatimer_event_type_get_type";
+
+    "alsatimer_get_sysname";
   local:
     *;
 };
diff --git a/src/timer/query.c b/src/timer/query.c
index d112a5f..60741cf 100644
--- a/src/timer/query.c
+++ b/src/timer/query.c
@@ -2,5 +2,65 @@
 #include "query.h"
 #include "privates.h"
 
+#include <stdbool.h>
+#include <errno.h>
+
+#include <libudev.h>
+
+#define TIMER_SYSNAME_TEMPLATE  "timer"
+
 // For error handling.
 G_DEFINE_QUARK("alsatimer-error", alsatimer_error)
+
+static bool check_existence(char *sysname, GError **error)
+{
+    struct udev *ctx;
+    struct udev_device *dev;
+    bool result;
+
+    ctx = udev_new();
+    if (ctx == NULL) {
+        generate_error(error, errno);
+        return false;
+    }
+
+    dev = udev_device_new_from_subsystem_sysname(ctx, "sound", sysname);
+    if (dev == NULL) {
+        generate_error(error, errno);
+        result = false;
+    } else {
+        result = true;
+    }
+    udev_device_unref(dev);
+
+    udev_unref(ctx);
+
+    return result;
+}
+
+/**
+ * alsatimer_get_sysname:
+ * @sysname: (out): The string for sysname of ALSA Timer.
+ * @error: A #GError.
+ *
+ * Allocate sysname for ALSA Timer and return it when it exists.
+ */
+void alsatimer_get_sysname(char **sysname, GError **error)
+{
+    char *name;
+
+    g_return_if_fail(sysname != NULL);
+
+    name = strdup(TIMER_SYSNAME_TEMPLATE);
+    if (name == NULL) {
+        generate_error(error, ENOMEM);
+        return;
+    }
+
+    if (!check_existence(name, error)) {
+        g_free(name);
+        return;
+    }
+
+    *sysname = name;
+}
diff --git a/src/timer/query.h b/src/timer/query.h
index ec3d941..bc2d12a 100644
--- a/src/timer/query.h
+++ b/src/timer/query.h
@@ -7,6 +7,8 @@
 
 G_BEGIN_DECLS
 
+void alsatimer_get_sysname(char **sysname, GError **error);
+
 G_END_DECLS
 
 #endif
-- 
2.47.3