Draft: Add small ctypes library

CMakeLists.txt

@@ -3,7 +3,7 @@ include(CheckFunctionExists)
 include(CheckSymbolExists)
 
 PROJECT(ucode C)
-ADD_DEFINITIONS(-Os -Wall -Werror --std=gnu99 -ffunction-sections -fwrapv -D_GNU_SOURCE)
+ADD_DEFINITIONS(-Os -Wall -Werror --std=gnu11 -ffunction-sections -fwrapv -D_GNU_SOURCE)
 
 IF(CMAKE_C_COMPILER_VERSION VERSION_GREATER 6)
 	ADD_DEFINITIONS(-Wextra -Werror=implicit-function-declaration)
@@ -27,6 +27,7 @@ OPTION(RTNL_SUPPORT "Route Netlink plugin support" ${LINUX})
 OPTION(NL80211_SUPPORT "Wireless Netlink plugin support" ${LINUX})
 OPTION(RESOLV_SUPPORT "NS resolve plugin support" ON)
 OPTION(STRUCT_SUPPORT "Struct plugin support" ON)
+OPTION(CTYPES_SUPPORT "Ctypes plugin support" ON)
 OPTION(ULOOP_SUPPORT "Uloop plugin support" ON)
 
 SET(LIB_SEARCH_PATH "${CMAKE_INSTALL_PREFIX}/lib/ucode/*.so:${CMAKE_INSTALL_PREFIX}/share/ucode/*.uc:./*.so:./*.uc" CACHE STRING "Default library search path")
@@ -192,6 +193,17 @@ IF(STRUCT_SUPPORT)
   ENDIF()
 ENDIF()
 
+IF(CTYPES_SUPPORT)
+  FIND_LIBRARY(ffi NAMES ffi)
+  FIND_PATH(ffi_include_dir NAMES ffi.h)
+  INCLUDE_DIRECTORIES(${ffi_include_dir})
+  SET(LIBRARIES ${LIBRARIES} ctypes_lib)
+  ADD_LIBRARY(ctypes_lib MODULE lib/ctypes.c)
+  SET_TARGET_PROPERTIES(ctypes_lib PROPERTIES OUTPUT_NAME ctypes PREFIX "")
+  TARGET_LINK_OPTIONS(ctypes_lib PRIVATE ${UCODE_MODULE_LINK_OPTIONS})
+  TARGET_LINK_LIBRARIES(ctypes_lib ${ffi})
+ENDIF()
+
 IF(ULOOP_SUPPORT)
   FIND_LIBRARY(ubox NAMES ubox)
   FIND_PATH(uloop_include_dir NAMES libubox/uloop.h)

examples/ctypes.uc

@@ -0,0 +1,57 @@
+const c = require("ctypes");
+const struct = require("struct");
+
+const sizeof = (abbreviation) => length(struct.pack(abbreviation));
+
+const abbreviation_to_ffi = {
+  i: c.ffi_type.sint,
+  P: c.ffi_type.pointer,
+  N: c.ffi_type["uint" + sizeof("N") * 8],
+};
+
+function attach(dl_handle, fun) {
+  const params_list = split(fun.params, "");
+  const cif = c.prep(
+    c.const.FFI_DEFAULT_ABI,
+    ...map(params_list, (a) => abbreviation_to_ffi[a])
+  );
+  return function (...args) {
+    const packed = struct.pack(fun.params, 0, ...args);
+    const return_buffer = c.ptr(packed);
+    const s = c.symbol(dl_handle, fun.name);
+    assert(s != null);
+    assert(cif.call(s, return_buffer));
+    return struct.unpack(
+      substr(fun.params, 0, 1),
+      return_buffer.ucv_string_new()
+    )[0];
+  };
+}
+
+const libc = {};
+for (fun in [
+  { name: "dlopen", params: "PPi" },
+  { name: "strlen", params: "NP" },
+]) {
+  libc[fun.name] = attach(c.const.RTLD_DEFAULT, fun);
+}
+
+function dlopen(library_name) {
+  const library_name_copy = c.ptr(library_name);
+  const return_ptr = libc.dlopen(library_name_copy.as_int(), c.const.RTLD_NOW);
+  assert(library_name_copy.drop());
+  assert(return_ptr != 0);
+  return c.ptr(return_ptr);
+}
+
+const c_sqlite_version = attach(dlopen("libsqlite3.so.0"), {
+  name: "sqlite3_libversion",
+  params: "P",
+});
+function sqlite_version() {
+  const return_ptr = c_sqlite_version();
+  const len = libc.strlen(return_ptr);
+  return c.ptr(return_ptr).ucv_string_new(len);
+}
+
+print("sqlite version: ", sqlite_version(), "\n");