[FOLD]

Author: vinniefalco

include/boost/http_proto/service/zlib_service.hpp

@@ -24,9 +24,9 @@ namespace zlib {
 struct stream_t
 {
     using alloc_func = void*(*)(void*, unsigned int, unsigned int);
-    using free_func = void(*)(void*, void const*);
+    using free_func = void(*)(void*, void*);
 
-    unsigned char const*next_in;    // next input byte
+    unsigned char*      next_in;    // next input byte
     unsigned int        avail_in;   // number of bytes available at next_in
     unsigned long       total_in;   // total number of input bytes read so far
 
@@ -37,8 +37,8 @@ struct stream_t
     char const*         msg;        // last error message, NULL if no error
     void*               state;      // not visible by applications
 
-    alloc_func          alloc;      // used to allocate internal state
-    free_func           free;       // used to deallocate internal state
+    alloc_func          zalloc;     // used to allocate internal state
+    free_func           zfree;      // used to deallocate internal state
     void*               opaque;     // private data object passed to zalloc and zfree
 
     int                 data_type;  // best guess about the data type: binary or text

src_zlib/service/stream_cast.hpp

@@ -13,6 +13,7 @@
 #include <boost/http_proto/detail/config.hpp>
 #include <boost/http_proto/service/zlib_service.hpp>
 #include <zlib.h>
+#include <cstddef>
 
 namespace boost {
 namespace http_proto {
@@ -33,10 +34,10 @@ struct stream_cast_impl
         zs_.next_out    = st_.next_out;
         zs_.avail_out   = st_.avail_out;
         zs_.total_out   = st_.total_out;
-        zs_.msg         = st_.msg;
-        zs_.state       = st_.state;
-        zs_.alloc       = st_.zalloc;
-        zs_.free        = st_.zfree;
+        zs_.state       = reinterpret_cast<
+            internal_state*>(st_.state);
+        zs_.zalloc      = st_.zalloc;
+        zs_.zfree       = st_.zfree;
         zs_.opaque      = st_.opaque;
         zs_.data_type   = st_.data_type;
         zs_.adler       = st_.adler;
@@ -53,18 +54,18 @@ struct stream_cast_impl
         st_.total_out   = zs_.total_out;
         st_.msg         = zs_.msg;
         st_.state       = zs_.state;
-        st_.alloc       = zs_.zalloc;
-        st_.free        = zs_.zfree;
+        st_.zalloc      = zs_.zalloc;
+        st_.zfree       = zs_.zfree;
         st_.opaque      = zs_.opaque;
         st_.data_type   = zs_.data_type;
         st_.adler       = zs_.adler;
         st_.reserved    = zs_.reserved;
     }
 
-    z_stream_s&
+    z_stream_s*
     get() noexcept
     {
-        return *pzs_;
+        return pzs_;
     }
 
 private:
@@ -98,8 +99,42 @@ struct stream_cast_impl<false>
 
 //------------------------------------------------
 
+template<class T1, class T2>
+constexpr
+bool
+is_layout_identical()
+{
+#define SAME_FIELD(T1, T2, M)( \
+    (offsetof(T1,M)==offsetof(T2,M)) && \
+    (std::is_same<T1::M,T2::M>::value) && \
+    (sizeof(T1::M)==sizeof(T2::M)) )
+    return
+        sizeof(T1) == sizeof(T2)
+#if 0
+        SAME_FIELD(T1, T2, next_in)
+        &&
+        SAME_FIELD(T1, T2, avail_in) &&
+        SAME_FIELD(T1, T2, total_in) &&
+        SAME_FIELD(T1, T2, next_out) &&
+        SAME_FIELD(T1, T2, avail_out) &&
+        SAME_FIELD(T1, T2, total_out) &&
+        SAME_FIELD(T1, T2, msg) &&
+        SAME_FIELD(T1, T2, state) &&
+        SAME_FIELD(T1, T2, zalloc) &&
+        SAME_FIELD(T1, T2, zfree) &&
+        SAME_FIELD(T1, T2, opaque) &&
+        SAME_FIELD(T1, T2, data_type) &&
+        SAME_FIELD(T1, T2, adler) &&
+        SAME_FIELD(T1, T2, reserved)
+#endif
+        ;
+}
+
+//------------------------------------------------
+
 // VFALCO A pinch of undefined behavior here
-using stream_cast = stream_cast_impl<false>;
+using stream_cast = stream_cast_impl<
+    is_layout_identical<stream_t, z_stream_s>()>;
 
 } // zlib
 } // http_proto

src_zlib/service/zlib_service.cpp

@@ -169,8 +169,8 @@ void* zalloc(
     BOOST_ASSERT(same(&stream_t::total_out, &z_stream_s::total_out));
     BOOST_ASSERT(same(&stream_t::msg,       &z_stream_s::msg));
     BOOST_ASSERT(same(&stream_t::state,     &z_stream_s::state));
-    BOOST_ASSERT(same(&stream_t::alloc,     &z_stream_s::zalloc));
-    BOOST_ASSERT(same(&stream_t::free,      &z_stream_s::zfree));
+    BOOST_ASSERT(same(&stream_t::zalloc,    &z_stream_s::zalloc));
+    BOOST_ASSERT(same(&stream_t::zfree,     &z_stream_s::zfree));
     BOOST_ASSERT(same(&stream_t::opaque,    &z_stream_s::opaque));
     BOOST_ASSERT(same(&stream_t::data_type, &z_stream_s::data_type));
     BOOST_ASSERT(same(&stream_t::adler,     &z_stream_s::adler));