From 55f796b5ad339f13baf8dba953f9f195fb9618ed Mon Sep 17 00:00:00 2001
From: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Date: Mon, 18 Nov 2019 13:22:44 +0900
Subject: [PATCH] rawmidi: add global method to get list of directional
 subdevices for rawmidi device

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 src/rawmidi/alsarawmidi.map |   1 +
 src/rawmidi/query.c         | 100 ++++++++++++++++++++++++++++++++++++
 src/rawmidi/query.h         |   7 +++
 3 files changed, 108 insertions(+)

diff --git a/src/rawmidi/alsarawmidi.map b/src/rawmidi/alsarawmidi.map
index 5b375a2..31d8eee 100644
--- a/src/rawmidi/alsarawmidi.map
+++ b/src/rawmidi/alsarawmidi.map
@@ -6,6 +6,7 @@ ALSA_GOBJECT_0_0_0 {
     "alsarawmidi_get_device_id_list";
     "alsarawmidi_get_rawmidi_sysname";
     "alsarawmidi_get_rawmidi_devnode";
+    "alsarawmidi_get_subdevice_id_list";
   local:
     *;
 };
diff --git a/src/rawmidi/query.c b/src/rawmidi/query.c
index 4d035f0..3abdfb2 100644
--- a/src/rawmidi/query.c
+++ b/src/rawmidi/query.c
@@ -5,15 +5,22 @@
 #include <stdio.h>
 #include <errno.h>
 #include <stdbool.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
 
 #include <libudev.h>
 
+#include <sound/asound.h>
+
 // For error reporting.
 G_DEFINE_QUARK("alsarawmidi-error", alsarawmidi_error)
 
 // 'C' is required apart from emulation of Open Sound System.
 #define PREFIX_SYSNAME_TEMPLATE     "midiC%u"
 #define RAWMIDI_SYSNAME_TEMPLATE    "midiC%uD%u"
+#define CTL_SYSNAME_TEMPLATE        "controlC%u"
 
 static void prepare_udev_enum(struct udev_enumerate **enumerator, GError **error)
 {
@@ -296,3 +303,96 @@ void alsarawmidi_get_rawmidi_devnode(guint card_id, guint device_id,
     udev_device_unref(dev);
     udev_unref(ctx);
 }
+
+static void rawmidi_perform_ctl_ioctl(guint card_id, long request, void *data,
+                                      GError **error)
+{
+    unsigned int length;
+    char *sysname;
+    struct udev *ctx;
+    struct udev_device *dev;
+    const char *devnode;
+    int fd;
+
+    length = strlen(CTL_SYSNAME_TEMPLATE) + calculate_digits(card_id) + 1;
+    sysname = g_try_malloc0(length);
+    if (sysname == NULL) {
+        generate_error(error, ENOMEM);
+        return;
+    }
+    snprintf(sysname, length, CTL_SYSNAME_TEMPLATE, card_id);
+
+    ctx = udev_new();
+    if (ctx == NULL) {
+        generate_error(error, errno);
+        goto err_sysname;
+    }
+
+    dev = udev_device_new_from_subsystem_sysname(ctx, "sound", sysname);
+    if (dev == NULL) {
+        generate_error(error, errno);
+        goto err_ctx;
+    }
+
+    devnode = udev_device_get_devnode(dev);
+    if (devnode == NULL) {
+        generate_error(error, ENODEV);
+        goto err_device;
+    }
+
+    fd = open(devnode, O_RDONLY);
+    if (fd < 0) {
+        generate_error(error, errno);
+        goto err_device;
+    }
+
+    if (ioctl(fd, request, data) < 0)
+        generate_error(error, errno);
+err_device:
+    udev_device_unref(dev);
+err_ctx:
+    udev_unref(ctx);
+err_sysname:
+    g_free(sysname);
+}
+
+/**
+ * alsarawmidi_get_subdevice_id_list:
+ * @card: The numberical value for sound card to query.
+ * @device: The numerical value of rawmidi device to query.
+ * @direction: The direction of stream to query, one of
+ *             ALSARawmidiStreamDirection.
+ * @entries: (array length=entry_count)(out): The list of card.
+ * @entry_count: The number of entries.
+ * @error: A #GError.
+ */
+void alsarawmidi_get_subdevice_id_list(guint card, guint device,
+                                       ALSARawmidiStreamDirection direction,
+                                       guint **entries, gsize *entry_count,
+                                       GError **error)
+{
+    struct snd_rawmidi_info info = {
+        .card = card,
+        .device = device,
+        .stream = direction,
+        .subdevice = 0,
+    };
+    int i;
+
+    g_return_if_fail(entries != NULL);
+    g_return_if_fail(entry_count != NULL);
+
+    rawmidi_perform_ctl_ioctl(card, SNDRV_CTL_IOCTL_RAWMIDI_INFO, &info, error);
+    if (*error != NULL)
+        return;
+
+    *entries = g_try_malloc0_n(info.subdevices_count, sizeof(guint));
+    if (*entries == NULL) {
+        generate_error(error, ENOMEM);
+        return;
+    }
+
+    for (i = 0; i < info.subdevices_count; ++i)
+        (*entries)[i] = i;
+    *entry_count = info.subdevices_count;
+}
diff --git a/src/rawmidi/query.h b/src/rawmidi/query.h
index eb2b7c6..be5f2c9 100644
--- a/src/rawmidi/query.h
+++ b/src/rawmidi/query.h
@@ -5,6 +5,8 @@
 #include <glib.h>
 #include <glib-object.h>
 
+#include <rawmidi/alsarawmidi-enums.h>
+
 G_BEGIN_DECLS
 
 void alsarawmidi_get_device_id_list(guint card_id,
@@ -17,6 +19,11 @@ void alsarawmidi_get_rawmidi_sysname(guint card_id, guint device_id,
 void alsarawmidi_get_rawmidi_devnode(guint card_id, guint device_id,
                                      char **devnode, GError **error);
 
+void alsarawmidi_get_subdevice_id_list(guint card, guint device,
+                                       ALSARawmidiStreamDirection direction,
+                                       guint **entries, gsize *entry_count,
+                                       GError **error);
+
 G_END_DECLS
 
 #endif
-- 
2.47.3