Since we can't redistribute vciapi.dll for the HMS Ixxat VCI driver, we load it only if it is required. #5

Author: mupfdev

CMakeLists.txt

@@ -24,12 +24,21 @@ include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/deps.cmake)
 
 target_link_libraries(
   ${PROJECT_NAME}
+  PRIVATE
   ${PLATFORM_LIBS}
 )
 
+if(WIN32 AND MSVC)
+  # Ensure the library can be loaded without vciapi.dll present.
+  # vciapi.dll will only be loaded when an Ixxat (VCI) function is called.
+  target_link_options(${PROJECT_NAME} PRIVATE /DELAYLOAD:vciapi.dll)
+  target_link_libraries(${PROJECT_NAME} PRIVATE delayimp)
+endif()
+
 if(UNIX)
   target_link_libraries(
     ${PROJECT_NAME}
+    PRIVATE
     socketcan
   )
 

cmake/deps.cmake

@@ -27,8 +27,7 @@ if(WIN32)
 
     BUILD_COMMAND ${CMAKE_COMMAND} -E echo "Skipping build step."
 
-    INSTALL_COMMAND ${CMAKE_COMMAND} -E copy
-      ${IXXAT_PATH}/sdk/vci/bin/${IXXAT_PLATFORM}/release/vciapi.dll ${CMAKE_CURRENT_BINARY_DIR}/
+    INSTALL_COMMAND ${CMAKE_COMMAND} -E echo "Skipping install step."
 
     PATCH_COMMAND ${CMAKE_COMMAND} -E copy
       "${CMAKE_CURRENT_SOURCE_DIR}/cmake/dep_ixxat.cmake" ${IXXAT_PATH}/CMakeLists.txt

src/CANvenient.c

@@ -8,8 +8,12 @@
  *
  **/
 
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
+#ifdef _WIN32
+#include <windows.h>
+#endif
 
 #include "CANvenient.h"
 #include "drivers/CANvenient_internal.h"
@@ -19,6 +23,11 @@
 #include "drivers/CANvenient_Softing.h"
 #include "drivers/CANvenient_PEAK.h"
 
+#ifdef _WIN32
+static HMODULE vciapi_dll_handle = NULL;
+static bool is_vciapi_dll_available = false;
+#endif
+
 struct can_iface can_interface[CAN_MAX_INTERFACES] = {0};
 char can_error_reason[1024] = {0};
 
@@ -29,10 +38,37 @@ CANVENIENT_API int can_find_interfaces_mask(u32 vendor_mask)
         return 0;
     }
 
-    if (vendor_mask & CAN_VENDOR_IXXAT)
+#ifdef _WIN32
+    static bool once_checked_vciapi_dll = false;
+
+    // https://github.com/CANopenTerm/CANopenTerm/issues/109#issuecomment-4320171025
+    if (! once_checked_vciapi_dll)
+    {
+        if (GetFileAttributesA("vciapi.dll") != INVALID_FILE_ATTRIBUTES)
+        {
+            vciapi_dll_handle = LoadLibraryA("vciapi.dll");
+            if (! vciapi_dll_handle)
+            {
+                puts("vciapi.dll not found. Ixxat interfaces will be ignored.");
+                is_vciapi_dll_available = false;
+            }
+            else
+            {
+                is_vciapi_dll_available = true;
+            }
+        }
+        else
+        {
+            puts("vciapi.dll not found. Ixxat interfaces will be ignored.");
+        }
+
+        once_checked_vciapi_dll = true;
+    }
+    if (vendor_mask & CAN_VENDOR_IXXAT && is_vciapi_dll_available)
     {
         ixxat_find_interfaces();
     }
+
     if (vendor_mask & CAN_VENDOR_PEAK)
     {
         peak_find_interfaces();
@@ -41,14 +77,17 @@ CANVENIENT_API int can_find_interfaces_mask(u32 vendor_mask)
     {
         kvaser_find_interfaces();
     }
-    if (vendor_mask & CAN_VENDOR_SOCKETCAN)
-    {
-        socketcan_find_interfaces();
-    }
+
     if (vendor_mask & CAN_VENDOR_SOFTING)
     {
         softing_find_interfaces();
     }
+#endif
+
+    if (vendor_mask & CAN_VENDOR_SOCKETCAN)
+    {
+        socketcan_find_interfaces();
+    }
 
     return 0;
 }