fix crc32 in static build (#488)

fix crc32 in static build

res/scripts/stdmin.lua

@@ -26,36 +26,21 @@ function __vc_Canvas_set_data(self, data)
     self:_set_data(tostring(_ffi.cast("uintptr_t", canvas_ffi_buffer)))
 end
 
-_ffi.cdef([[
-    unsigned long crc32(unsigned long crc, const char *buf, unsigned len);
-]])
-
-local zlib
-if _ffi.os == "Windows" then
-    zlib = _ffi.load("zlib1")
-elseif _ffi.os == "OSX" then
-    zlib = _ffi.load("z")
-elseif _ffi.os == "Linux" then
-    zlib = _ffi.load("libz.so.1")
-else
-    error("platform does not support zlib " .. _ffi.os)
-end
-
 function crc32(bytes, chksum)
     local chksum = chksum or 0
 
     local length = #bytes
-    if type(bytes) == "string" then
-        return zlib.crc32(chksum, bytes, length)
-    elseif type(bytes) == "table" then
+    if type(bytes) == "table" then
+        local buffer_len = _ffi.new('int[1]', length)
         local buffer = _ffi.new(
             string.format("char[%s]", length)
         )
         for i=1, length do
             buffer[i - 1] = bytes[i]
         end
-        return zlib.crc32(chksum, buffer, length)
+        bytes = _ffi.string(buffer, buffer_len[0])
     end
+    return _crc32(bytes, chksum)
 end
 
 -- Check if given table is an array

src/logic/scripting/lua/libs/api_lua.hpp

@@ -56,6 +56,7 @@ extern const luaL_Reg transformlib[];
 
 // Lua Overrides
 extern int l_print(lua::State* L);
+extern int l_crc32(lua::State* L);
 
 namespace lua {
     inline uint check_argc(lua::State* L, int a) {

src/logic/scripting/lua/lua_engine.cpp

@@ -84,6 +84,7 @@ static void create_libs(State* L, StateType stateType) {
     }
 
     addfunc(L, "print", lua::wrap<l_print>);
+    addfunc(L, "_crc32", lua::wrap<l_crc32>);
 }
 
 void lua::init_state(State* L, StateType stateType) {

src/logic/scripting/lua/lua_overrides.cpp

@@ -1,4 +1,5 @@
 #include <iostream>
+#include <zlib.h>
 
 #include "libs/api_lua.hpp"
 
@@ -25,3 +26,27 @@ int l_print(lua::State* L) {
     *output_stream << std::endl;
     return 0;
 }
+
+int l_crc32(lua::State* L) {
+    auto value = lua::tointeger(L, 2);
+    if (lua::isstring(L, 1)) {
+        auto string = lua::tolstring(L, 1);
+        return lua::pushinteger(
+            L,
+            crc32(
+                value,
+                reinterpret_cast<const ubyte*>(string.data()),
+                string.length()
+            )
+        );
+    } else if (auto bytearray = lua::touserdata<lua::LuaBytearray>(L, 1)) {
+        auto& bytes = bytearray->data();
+        return lua::pushinteger(L, crc32(value, bytes.data(), bytes.size()));
+    } else if (lua::istable(L, 1)) {
+        std::vector<ubyte> bytes;
+        lua::read_bytes_from_table(L, 1, bytes);
+        return lua::pushinteger(L, crc32(value, bytes.data(), bytes.size()));
+    } else {
+        throw std::runtime_error("invalid argument 1");
+    }
+}