Add API.last_error

appveyor.yml

@@ -1,5 +1,7 @@
 version: '{build}'
 
+image: Visual Studio 2019
+
 init:
   # use a minimal path
   - set PATH=C:\ruby%ruby_version%\bin;C:\Program Files\7-Zip;C:\Program Files\AppVeyor\BuildAgent;C:\Program Files\Git\cmd;C:\Windows\system32
@@ -26,6 +28,10 @@ test_script:
 environment:
   matrix:
     - ruby_version: _trunk
+    - ruby_version: 30-x64
+    - ruby_version: 30
+    - ruby_version: 27-x64
+    - ruby_version: 27
     - ruby_version: 26-x64
     - ruby_version: 26
     - ruby_version: 25-x64
@@ -34,12 +40,6 @@ environment:
     - ruby_version: 24
     - ruby_version: 23-x64
     - ruby_version: 23
-    - ruby_version: 22-x64
-    - ruby_version: 22
-    - ruby_version: 21-x64
-    - ruby_version: 21
-    - ruby_version: 200-x64
-    - ruby_version: 200
 
 matrix:
   allow_failures:

ext/win32/api.c

@@ -62,6 +62,35 @@ typedef struct {
     int prototype[20];
 } Win32API;
 
+typedef struct ThreadData {
+   DWORD win32api_error;
+} ThreadData;
+
+static inline ThreadData* thread_data_get(void);
+static ID id_thread_data;
+
+static ThreadData* thread_data_init(void)
+{
+   ThreadData* td;
+   VALUE obj;
+
+   obj = Data_Make_Struct(rb_cObject, ThreadData, NULL, -1, td);
+   rb_thread_local_aset(rb_thread_current(), id_thread_data, obj);
+
+   return td;
+}
+
+static inline ThreadData* thread_data_get()
+{
+   VALUE obj = rb_thread_local_aref(rb_thread_current(), id_thread_data);
+
+   if(obj != Qnil && TYPE(obj) == T_DATA){
+      return (ThreadData*) DATA_PTR(obj);
+   }
+
+   return thread_data_init();
+}
+
 static void api_free(Win32API* ptr){
    if(ptr->library)
       FreeLibrary(ptr->library);
@@ -781,6 +810,7 @@ static VALUE api_call(int argc, VALUE* argv, VALUE self){
    uintptr_t return_value;
    int i = 0;
    int len;
+   ThreadData* thread_data = thread_data_get();
 
    struct{
       uintptr_t params[20];
@@ -975,6 +1005,8 @@ static VALUE api_call(int argc, VALUE* argv, VALUE self){
         }
    }
 
+   thread_data->win32api_error = GetLastError();
+
    /* Return the appropriate type based on the return type specified
     * in the constructor.
     */
@@ -1029,6 +1061,21 @@ static VALUE api_call(int argc, VALUE* argv, VALUE self){
    return v_return;
 }
 
+/*
+ * call-seq:
+ *    Win32::API.last_error
+ *
+ * Return the last Win32 error code of the current executing thread.
+ *
+ * The error code shouldn't be retrieved by calling GetLastError() manually
+ * because Ruby's internal code may call other Win32 API and reset the error
+ * code before it.
+ */
+static VALUE get_last_error(VALUE self)
+{
+   return INT2NUM(thread_data_get()->win32api_error);
+}
+
 /*
  * Wraps the Windows API functions in a Ruby interface.
  */
@@ -1061,6 +1108,9 @@ void Init_api(){
    /* Miscellaneous */
    rb_define_alloc_func(cAPI, api_allocate);
 
+   /* GetLastError alternative */
+   rb_define_singleton_method(cAPI, "last_error", get_last_error, 0);
+
    /* Win32::API Instance Methods */
    rb_define_method(cAPI, "initialize", api_init, -1);
    rb_define_method(cAPI, "call", api_call, -1);

test/test_win32_api.rb

@@ -43,6 +43,12 @@ def test_call_return_value_on_failure
       assert_equal(0xFFFFFFFF, @gfa.call('C:/foobarbazblah'))
    end
 
+   def test_last_error
+      @gfa.call('C:/foobarbazblah')
+      error_file_not_found = 2
+      assert_equal(error_file_not_found, API.last_error)
+   end
+
    def test_dll_name
       assert_respond_to(@gcd, :dll_name)
       assert_equal('kernel32', @gcd.dll_name)