From 0df6f5c7d8f08bdf6c413ae8e1e3ff9c111f35c5 Mon Sep 17 00:00:00 2001
From: Vincent Isambart <vincent.isambart@gmail.com>
Date: Thu, 25 Feb 2021 10:30:57 +0900
Subject: [PATCH] Allow to pass callbacks in varargs

---
 ext/ffi_c/Variadic.c            | 15 +++++++++++++--
 spec/ffi/callback_spec.rb       |  8 +++++++-
 spec/ffi/fixtures/ClosureTest.c | 12 ++++++++++++
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/ext/ffi_c/Variadic.c b/ext/ffi_c/Variadic.c
index d9d7fd44f..d18a14338 100644
--- a/ext/ffi_c/Variadic.c
+++ b/ext/ffi_c/Variadic.c
@@ -168,7 +168,8 @@ variadic_invoke(VALUE self, VALUE parameterTypes, VALUE parameterValues)
     ffi_type* ffiReturnType;
     Type** paramTypes;
     VALUE* argv;
-    int paramCount = 0, fixedCount = 0, i;
+    VALUE* callbackParameters = NULL;
+    int paramCount = 0, fixedCount = 0, callbackCount = 0, i;
     ffi_status ffiStatus;
     rbffi_frame_t frame = { 0 };
 
@@ -211,6 +212,16 @@ variadic_invoke(VALUE self, VALUE parameterTypes, VALUE parameterValues)
                 Data_Get_Struct(rbType, Type, paramTypes[i]);
                 break;
 
+            case NATIVE_FUNCTION:
+            case NATIVE_CALLBACK:
+                if (!rb_obj_is_kind_of(rbType, rbffi_FunctionTypeClass)) {
+                    VALUE typeName = rb_funcall2(rbType, rb_intern("inspect"), 0, NULL);
+                    rb_raise(rb_eTypeError, "Incorrect parameter type (%s)", RSTRING_PTR(typeName));
+                }
+                REALLOC_N(callbackParameters, VALUE, callbackCount + 1);
+                callbackParameters[callbackCount++] = rbType;
+                break;
+
             default:
                 break;
         }
@@ -248,7 +259,7 @@ variadic_invoke(VALUE self, VALUE parameterTypes, VALUE parameterValues)
     }
 
     rbffi_SetupCallParams(paramCount, argv, -1, paramTypes, params,
-        ffiValues, NULL, 0, invoker->rbEnums);
+        ffiValues, callbackParameters, callbackCount, invoker->rbEnums);
 
     rbffi_frame_push(&frame);
 
diff --git a/spec/ffi/callback_spec.rb b/spec/ffi/callback_spec.rb
index 58e5c8156..53ff1e49f 100644
--- a/spec/ffi/callback_spec.rb
+++ b/spec/ffi/callback_spec.rb
@@ -49,6 +49,7 @@ class S8F32S32 < FFI::Struct
       callback :cbVrU32, [ ], :uint
       callback :cbVrL, [ ], :long
       callback :cbVrUL, [ ], :ulong
+      callback :cbVrD, [ ], :double
       callback :cbVrS64, [ ], :long_long
       callback :cbVrU64, [ ], :ulong_long
       callback :cbVrP, [], :pointer
@@ -86,7 +87,7 @@ class S8F32S32 < FFI::Struct
       attach_variable :pVrS8, :gvar_pointer, :pointer
       attach_function :testGVarCallbackVrS8, :testClosureVrB, [ :pointer ], :char
       attach_function :testOptionalCallbackCrV, :testOptionalClosureBrV, [ :cbCrV, :char ], :void
-
+      attach_function :testCallbackVrDva, :testClosureVrDva, [ :double, :varargs ], :double
     end
 
     it "returning :char (0)" do
@@ -261,6 +262,11 @@ class S8F32S32 < FFI::Struct
       expect(LibTest.testCallbackVrZ { true }).to be true
     end
 
+    it "returning double" do
+      pr = proc { 42.0 }
+      expect(LibTest.testCallbackVrDva(3.0, :cbVrD, pr)).to eq(45.0)
+    end
+
     it "returning :pointer (nil)" do
       expect(LibTest.testCallbackVrP { nil }).to be_null
     end
diff --git a/spec/ffi/fixtures/ClosureTest.c b/spec/ffi/fixtures/ClosureTest.c
index c477be8a7..daabe0e88 100644
--- a/spec/ffi/fixtures/ClosureTest.c
+++ b/spec/ffi/fixtures/ClosureTest.c
@@ -6,6 +6,7 @@
 
 #include <stdlib.h>
 #include <stdbool.h>
+#include <stdarg.h>
 #ifndef _WIN32
 # include <pthread.h>
 #else
@@ -13,6 +14,17 @@
 # include <process.h>
 #endif
 
+double testClosureVrDva(double d, ...) {
+    va_list args;
+    double (*closure)(void);
+
+    va_start(args, d);
+    closure = va_arg(args, double (*)(void));
+    va_end(args);
+
+    return d + closure();
+}
+
 #define R(T, rtype) rtype testClosureVr##T(rtype (*closure)(void)) { \
     return closure != NULL ? (*closure)() : (rtype) 0; \
 }