Get C strings passing from Python to C

integration_tests/test_c_interop_02.py

@@ -24,6 +24,10 @@ def f_i16_i16(x: i16) -> i16:
 def f_i8_i8(x: i8) -> i8:
     pass
 
+@ccall
+def f_str_i32(x: str) -> i32:
+    pass
+
 def test_c_callbacks():
     xf64: f64
     xf64 = 3.3
@@ -49,4 +53,9 @@ def test_c_callbacks():
     xi8 = 3
     assert f_i8_i8(xi8) == 4
 
+    s: str
+    s = "Hello World!"
+    print(f_str_i32(s))
+    assert f_str_i32(s) == 3
+
 test_c_callbacks()

integration_tests/test_c_interop_02b.c

@@ -1,3 +1,5 @@
+#include <string.h>
+
 #include "test_c_interop_02b.h"
 
 double f_f64_f64(double x) {
@@ -23,3 +25,7 @@ int16_t f_i16_i16(int16_t x) {
 int8_t f_i8_i8(int8_t x) {
     return x+1;
 }
+
+int32_t f_str_i32(char *x) {
+    return strlen(x);
+}

integration_tests/test_c_interop_02b.h

@@ -10,6 +10,7 @@ int64_t f_i64_i64(int64_t x);
 int32_t f_i32_i32(int32_t x);
 int16_t f_i16_i16(int16_t x);
 int8_t  f_i8_i8  (int8_t  x);
+int32_t f_str_i32(char   *x);
 
 
 #endif // TEST_C_INTEROP_02B

src/runtime/ltypes/ltypes.py

@@ -129,6 +129,9 @@ def convert_type_to_ctype(arg):
                 return ctypes.c_int8
             elif arg == CPtr:
                 return ctypes.c_void_p
+            elif arg == str:
+                #return ctypes.POINTER(ctypes.c_char)
+                return ctypes.c_void_p
             elif arg is None:
                 raise NotImplementedError("Type cannot be None")
             elif isinstance(arg, Array):
@@ -176,6 +179,21 @@ def get_crtlib_path():
     def __call__(self, *args, **kwargs):
         if len(kwargs) > 0:
             raise Exception("kwargs are not supported")
+        new_args = []
+        for arg in args:
+            if isinstance(arg, str):
+                # wrap strings into c_char_p
+                #b = arg.encode("utf-8")
+                #new_args.append(ctypes.c_char_p(bytes(arg, "utf-8")))
+                #new_args.append(bytes(arg, "utf-8"))
+                b = "xxxxxxx"
+                b = ctypes.create_string_buffer(str.encode(b))
+                print(type(b))
+                new_args.append(b)
+            else:
+                new_args.append(arg)
+        print(self.cf.argtypes)
+        print(new_args)
         return self.cf(*args)