Match gamepad by USB vendor+product on Linux

src/input.c

@@ -67,15 +67,50 @@ static GLFWbool initJoysticks(void)
     return _glfw.joysticksInitialized = GLFW_TRUE;
 }
 
+uint16_t parseHexDigit(char c)
+{
+    if (c >= '0' && c <= '9') return c - '0';
+    if (c >= 'a' && c <= 'f') return c - 'a' + 10;
+    if (c >= 'A' && c <= 'F') return c - 'A' + 10;
+    assert(GLFW_FALSE);
+}
+
+struct vendor_product
+{
+    uint16_t vendor;
+    uint16_t product;  
+};
+
+static struct vendor_product parseGUID(const char* guid)
+{
+    struct vendor_product result;
+    result.vendor = parseHexDigit(guid[8]) | (parseHexDigit(guid[9]) << 8);
+    result.product = parseHexDigit(guid[16]) | (parseHexDigit(guid[17]) << 8);
+    return result;
+}
+
 // Finds a mapping based on joystick GUID
 //
 static _GLFWmapping* findMapping(const char* guid)
 {
-    int i;
+    struct vendor_product this;
 
-    for (i = 0;  i < _glfw.mappingCount;  i++)
+    // exact match
+    for (int i = 0;  i < _glfw.mappingCount;  i++)
     {
-        if (strcmp(_glfw.mappings[i].guid, guid) == 0)
+        if (strncmp(_glfw.mappings[i].guid, guid, 32) == 0)
+            return _glfw.mappings + i;
+    }
+
+    // only match vendor product
+
+    this = parseGUID(guid);
+    
+    for (int i = 0;  i < _glfw.mappingCount;  i++)
+    {
+        struct vendor_product that = parseGUID(_glfw.mappings[i].guid);
+
+        if (memcmp(&this, &that, sizeof(struct vendor_product)) == 0)
             return _glfw.mappings + i;
     }
 

src/internal.h

@@ -74,6 +74,7 @@ typedef struct _GLFWmonitor     _GLFWmonitor;
 typedef struct _GLFWcursor      _GLFWcursor;
 typedef struct _GLFWmapelement  _GLFWmapelement;
 typedef struct _GLFWmapping     _GLFWmapping;
+typedef struct _GLFWusbinfo     _GLFWusbinfo;
 typedef struct _GLFWjoystick    _GLFWjoystick;
 typedef struct _GLFWtls         _GLFWtls;
 typedef struct _GLFWmutex       _GLFWmutex;
@@ -631,6 +632,16 @@ struct _GLFWmapping
     _GLFWmapelement axes[6];
 };
 
+// USB vendor, product, version
+//
+struct _GLFWusbinfo
+{
+    uint16_t bustype;
+	uint16_t vendor;
+	uint16_t product;
+	uint16_t version;
+};
+
 // Joystick structure
 //
 struct _GLFWjoystick
@@ -646,6 +657,7 @@ struct _GLFWjoystick
     char            name[128];
     void*           userPointer;
     char            guid[33];
+    _GLFWusbinfo    usbInfo;
     _GLFWmapping*   mapping;
 
     // This is defined in platform.h

src/linux_joystick.c

@@ -172,6 +172,12 @@ static GLFWbool openJoystickDevice(const char* path)
 
     char guid[33] = "";
 
+    _GLFWusbinfo usbinfo;
+    usbinfo.bustype = id.bustype;
+    usbinfo.vendor  = id.vendor;
+    usbinfo.product = id.product;
+    usbinfo.version = id.version;
+
     // Generate a joystick GUID that matches the SDL 2.0.5+ one
     if (id.vendor && id.product && id.version)
     {
@@ -231,6 +237,7 @@ static GLFWbool openJoystickDevice(const char* path)
         close(linjs.fd);
         return GLFW_FALSE;
     }
+    js->usbInfo = usbinfo;
 
     strncpy(linjs.path, path, sizeof(linjs.path) - 1);
     memcpy(&js->linjs, &linjs, sizeof(linjs));