Added NIF -> FFI bridge

Makefile

@@ -0,0 +1,18 @@
+CC=gcc
+CFLAGS=
+OBJ = ffi_nif.o
+TARGET = ffi_nif.so
+LIBS += -ldl -lffi
+ERTS_INCLUDE_PATH=/home/josh/Playground/erlangs/erts-6.0/include
+DIR=c_src
+
+$(DIR)/%.o: $(DIR)/%.c $(DEPS)
+	$(CC) -c -o $@ $< $(CFLAGS) -I$(ERTS_INCLUDE_PATH)
+
+$(TARGET): $(DIR)/$(OBJ)
+	$(CC) -shared -o $@ $^ $(CFLAGS) $(LIBS)
+
+.PHONY : $(TARGET)
+
+clean :
+	$(RM) $(DIR)/*.o *.so

c_src/ffi_nif.c

@@ -0,0 +1,136 @@
+#include <sys/types.h>
+#include <stdio.h>
+#include <erl_nif.h>
+#include <ffi.h>
+
+#define MAXLEN 1024
+
+enum {
+  VOID = 0,
+  STRING,
+  INT
+} TYPE;
+
+static void call(int argc, ffi_type **args, void **values, ffi_type* returnType) {
+  ffi_cif cif;
+  int returnValue;
+
+  if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, argc, returnType, args) == FFI_OK) {
+    ffi_call(&cif, (void*)puts, &returnValue, values);
+  }
+}
+
+static ERL_NIF_TERM nif_call(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+  char library[MAXLEN],
+       function[MAXLEN];
+
+  int argumentsLength, valuesLength, returnType, returnValue, i;
+
+  ErlNifCharEncoding encoding = ERL_NIF_LATIN1;
+
+  if (!enif_get_atom(env, argv[0], library, MAXLEN, encoding)) {
+    return enif_make_badarg(env);
+  }
+
+  if (!enif_get_atom(env, argv[1], function, MAXLEN, encoding)) {
+    return enif_make_badarg(env);
+  }
+
+  if (!enif_get_list_length(env, argv[2], &argumentsLength)) {
+    return enif_make_badarg(env);
+  }
+
+  if (!enif_get_int(env, argv[3], &returnType)) {
+    return enif_make_badarg(env);
+  }
+
+  if (!enif_get_list_length(env, argv[4], &valuesLength)) {
+    return enif_make_badarg(env);
+  }
+
+  if (valuesLength != argumentsLength) {
+    return enif_make_badarg(env);
+  }
+
+  ffi_type *ffiArgs[argumentsLength], *ffiReturnType = &ffi_type_sint;
+  int args[argumentsLength];
+  void *ffiValues[valuesLength];
+  ERL_NIF_TERM head, tail = argv[2];
+  uint type;
+
+  for (i=0;enif_get_list_cell(env, tail, &head, &tail);i++) {
+    ffi_type *ffiType;
+
+    enif_get_uint(env, head, &type);
+
+    args[i] = type;
+
+    switch (type) {
+      case VOID:
+        ffiType = &ffi_type_void;
+        break;
+      case STRING:
+        ffiType = &ffi_type_pointer;
+        break;
+      case INT:
+        ffiType = &ffi_type_sint;
+        break;
+    }
+
+    ffiArgs[i] = ffiType;
+  }
+
+  tail = argv[4];
+
+  int intData;
+  char charData[MAXLEN];
+  char *s = charData;
+
+  for (i=0;enif_get_list_cell(env, tail, &head, &tail);i++) {
+    type = args[i];
+
+    switch (type) {
+      case VOID:
+        break;
+      case STRING:
+        enif_get_string(env, head, charData, MAXLEN, encoding);
+
+        ffiValues[i] = &s;
+
+        break;
+      case INT:
+        enif_get_int(env, head, &intData);
+
+        ffiValues[i] = &intData;
+
+        break;
+    }
+  }
+
+  switch (returnType) {
+    case VOID:
+      ffiReturnType = &ffi_type_void;
+      break;
+    case STRING:
+      ffiReturnType = &ffi_type_pointer;
+      break;
+    case INT:
+      ffiReturnType = &ffi_type_sint;
+      break;
+  }
+
+  printf("%s.%s() %d %d\n", library, function, argumentsLength, returnType);
+
+  call(argumentsLength, ffiArgs, ffiValues, ffiReturnType);
+
+  returnValue = 100;
+
+  return enif_make_int(env, returnValue);
+}
+
+static ErlNifFunc nif_funcs[] = {
+  {"nif_call", 5, nif_call}
+};
+
+ERL_NIF_INIT(Elixir.FFI, nif_funcs, NULL, NULL, NULL, NULL)