From ad6c25a3b2f0b4ae43b0cf4cfe6ad9ed376eb214 Mon Sep 17 00:00:00 2001
From: MiroKaku <50670906+MiroKaku@users.noreply.github.com>
Date: Wed, 25 Sep 2024 10:09:43 +0800
Subject: [PATCH] fix(core): distinguish the error states of VddAddDisplay.

---
 core/parsec-vdd.h | 17 +++++++++++------
 core/vdd-demo.cc  | 11 +++++++----
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/core/parsec-vdd.h b/core/parsec-vdd.h
index 8d38644..d9b7f47 100644
--- a/core/parsec-vdd.h
+++ b/core/parsec-vdd.h
@@ -255,17 +255,22 @@ static const int VDD_MAX_DISPLAYS = 8;
 
 // Core IoControl codes, see usage below.
 typedef enum {
-    VDD_IOCTL_ADD = 0x0022e004,
-    VDD_IOCTL_REMOVE = 0x0022a008,
-    VDD_IOCTL_UPDATE = 0x0022a00c,
-    VDD_IOCTL_VERSION = 0x0022e010,
+    VDD_IOCTL_ADD     = 0x0022e004, // CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800 + 1, METHOD_BUFFERED, FILE_READ_ACCESS | FILE_WRITE_ACCESS)
+    VDD_IOCTL_REMOVE  = 0x0022a008, // CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800 + 2, METHOD_BUFFERED, FILE_WRITE_ACCESS)
+    VDD_IOCTL_UPDATE  = 0x0022a00c, // CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800 + 3, METHOD_BUFFERED, FILE_WRITE_ACCESS)
+    VDD_IOCTL_VERSION = 0x0022e010, // CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800 + 4, METHOD_BUFFERED, FILE_READ_ACCESS | FILE_WRITE_ACCESS)
+
+    // new code in driver v0.45
+    // relates to IOCTL_UPDATE and per display state
+    // but unused in Parsec app
+    VDD_IOCTL_UNKONWN = 0x0022a00c, // CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800 + 5, METHOD_BUFFERED, FILE_WRITE_ACCESS)
 } VddCtlCode;
 
 // Generic DeviceIoControl for all IoControl codes.
 static DWORD VddIoControl(HANDLE vdd, VddCtlCode code, const void *data, size_t size)
 {
     if (vdd == NULL || vdd == INVALID_HANDLE_VALUE)
-        return 0;
+        return -1;
 
     BYTE InBuffer[32];
     ZeroMemory(InBuffer, sizeof(InBuffer));
@@ -285,7 +290,7 @@ static DWORD VddIoControl(HANDLE vdd, VddCtlCode code, const void *data, size_t
     if (!GetOverlappedResultEx(vdd, &Overlapped, &NumberOfBytesTransferred, 5000, FALSE))
     {
         CloseHandle(Overlapped.hEvent);
-        return 0;
+        return -1;
     }
 
     if (Overlapped.hEvent != NULL)
diff --git a/core/vdd-demo.cc b/core/vdd-demo.cc
index 0629601..7e05a94 100644
--- a/core/vdd-demo.cc
+++ b/core/vdd-demo.cc
@@ -36,8 +36,6 @@ int main()
         }
     });
 
-    updater.detach();
-
     // Print out guide.
     printf("Press A to add a virtual display.\n");
     printf("Press R to remove the last added.\n");
@@ -53,8 +51,13 @@ int main()
             case 'a':
                 if (displays.size() < VDD_MAX_DISPLAYS) {
                     int index = VddAddDisplay(vdd);
-                    displays.push_back(index);
-                    printf("Added a new virtual display, index: %d.\n", index);
+                    if (index != -1) {
+                        displays.push_back(index);
+                        printf("Added a new virtual display, index: %d.\n", index);
+                    }
+                    else {
+                        printf("Add virtual display failed.");
+                    }
                 }
                 else {
                     printf("Limit exceeded (%d), could not add more virtual displays.\n", VDD_MAX_DISPLAYS);