Add Linux Joystick Support

Add support for Linux joystick devices, this allows things like the EDTracker to
work, and possibly other devices.

1 files changed, 65 insertions, 0 deletions

diff --git a/tracker-linux-joystick/linux_joystick.cpp b/tracker-linux-joystick/linux_joystick.cpp
new file mode 100644
index 00000000..3369a29e
--- /dev/null
+++ b/tracker-linux-joystick/linux_joystick.cpp
@@ -0,0 +1,65 @@
+#include "ftnoir_tracker_linux_joystick.h"
+
+#include <QDir>
+#include <QFileInfo>
+#include <QVariant>
+
+// Discovery is done by searching for devices in the sys file system.
+//
+// Given a path like this
+// /sys/devices/pci0000:00/0000:00:14.0/usb1/1-10/1-10:1.2/0003:2341:8036.0170/input/input380/js0
+// we want to get this part of the string 2341:8036, it will allow us to
+// identify the device in the future.
+// alternative way of doing this https://stackoverflow.com/questions/21173988/linux-attempting-to-get-joystick-vendor-and-product-ids-via-ioctl-get-einval-i
+std::tuple<QString, QString> sysfsDeviceToJsDev(QFileInfo device) {
+    using ret = std::tuple<QString, QString>;
+    QString symlink = device.symLinkTarget();
+    QString js_dev = QString("/dev/input/%1").arg(device.fileName());
+
+    QRegExp sep(QString("[:.%1]").arg(QDir::separator()));
+    QString device_id = symlink.section(sep, -6, -5);
+    return ret(js_dev, device_id);
+}
+
+QList<linux_joystick> getJoysticks()
+{
+    char name[128];
+    QList<linux_joystick> joysticks;
+
+    QDir dir("/sys/class/input/");
+    dir.setNameFilters({ "js*" });
+    QFileInfoList list = dir.entryInfoList();
+    for (int i = 0; i < list.size(); ++i)
+    {
+        QFileInfo device = list.at(i);
+        auto [js_dev, device_id] = sysfsDeviceToJsDev(device);
+        int iFile = open(js_dev.toUtf8().data(), O_RDONLY | O_NONBLOCK);
+        if (iFile == -1) continue;
+        if (ioctl(iFile, JSIOCGNAME(sizeof(name)), &name) > 0)
+        {
+            linux_joystick j;
+            j.name = name;
+            j.dev = js_dev;
+            j.device_id = device_id;
+            joysticks.append(j);
+        }
+        close(iFile);
+
+    }
+
+    return joysticks;
+}
+
+QString getJoystickDevice(QString guid) {
+    QDir dir("/sys/class/input/");
+    dir.setNameFilters({ "js*" });
+    QFileInfoList list = dir.entryInfoList();
+    for (int i = 0; i < list.size(); ++i)
+    {
+        QFileInfo device = list.at(i);
+        auto [js_dev, device_id] = sysfsDeviceToJsDev(device);
+        if (device_id == guid) return js_dev;
+    }
+
+    return NULL;
+}