bridges/inc/vtablefactory.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
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  19
  20 #ifndef INCLUDED_BRIDGES_INC_VTABLEFACTORY_HXX
  21 #define INCLUDED_BRIDGES_INC_VTABLEFACTORY_HXX
  22
  23 #include <osl/mutex.hxx>
  24 #include <rtl/alloc.h>
  25 #include <rtl/ustring.hxx>
  26 #include <sal/types.h>
  27 #include <typelib/typedescription.hxx>
  28
  29 #include <unordered_map>
  30
  31 /*See: http://people.redhat.com/drepper/selinux-mem.html*/
  32 #if defined(LINUX) || defined(OPENBSD) || defined(FREEBSD) \
  33     || defined(NETBSD) || defined(DRAGONFLY) || defined (ANDROID) \
  34     || defined(HAIKU)
  35 #define USE_DOUBLE_MMAP
  36 #endif
  37
  38 namespace bridges { namespace cpp_uno { namespace shared {
  39
  40 /** Hand out vtable structures for interface type descriptions.
  41  */
  42 class VtableFactory {
  43 public:
  44     // This structure is not defined in the generic part, but instead has to be
  45     // defined individually for each CPP--UNO bridge:
  46     /** A vtable slot.
  47      */
  48     struct Slot;
  49
  50     /** A raw vtable block.
  51      */
  52     struct Block {
  53         /** The start of the raw vtable block.
  54
  55             It points to the start of the allocated memory block, whereas the
  56             vtable pointer typically points some bytes into the block (e.g.,
  57             skipping an RTTI pointer, see mapBlockToVtable).  Also, the block
  58             contains any generated code snippets, after the vtable itself.
  59          */
  60         void * start;
  61
  62 #ifdef USE_DOUBLE_MMAP
  63     /** When separately mmapping the block for writing and executing
  64             exec points to the same memory as start, except start is used
  65             exclusively for writing and exec for executing
  66          */
  67         void * exec;
  68
  69     /** File handle for the underlying anonymous file
  70          */
  71         int fd;
  72 #endif
  73
  74         /** The size of the raw vtable block, in bytes.
  75          */
  76         sal_Size size;
  77     };
  78
  79     /** The vtable structure corresponding to an interface type.
  80      */
  81     struct Vtables {
  82         /** The number of blocks/vtables.
  83          */
  84         sal_Int32 count;
  85
  86         /** An array of blocks, representing the multiple vtables of a
  87             (multiple-inheritance) type.
  88
  89             <p>A block is a raw vtable.  It points to the start of the allocated
  90             memory block, whereas the vtable pointer typically points some bytes
  91             into the block (e.g., skipping an RTTI pointer, see
  92             mapBlockToVtable).  Also, the block contains any generated code
  93             snippets, after the vtable itself.</p>
  94          */
  95         Block * blocks;
  96         Vtables()
  97             : count(0)
  98             , blocks(nullptr)
  99         {
 100         }
 101     };
 102
 103     VtableFactory();
 104
 105     ~VtableFactory();
 106
 107     /** Given an interface type description, return its corresponding vtable
 108         structure.
 109      */
 110     Vtables getVtables(typelib_InterfaceTypeDescription * type);
 111
 112     // This function is not defined in the generic part, but instead has to be
 113     // defined individually for each CPP--UNO bridge:
 114     /** Given a pointer to a block, turn it into a vtable pointer.
 115      */
 116     static Slot * mapBlockToVtable(void * block);
 117
 118 private:
 119     class GuardedBlocks;
 120     friend class GuardedBlocks;
 121
 122     class BaseOffset;
 123
 124     VtableFactory(VtableFactory const &) = delete;
 125     VtableFactory& operator =(const VtableFactory&) = delete;
 126
 127     bool createBlock(Block &block, sal_Int32 slotCount) const;
 128
 129     void freeBlock(Block const & block) const;
 130
 131     sal_Int32 createVtables(
 132         GuardedBlocks & blocks, BaseOffset const & baseOffset,
 133         typelib_InterfaceTypeDescription * type, sal_Int32 vtableNumber,
 134         typelib_InterfaceTypeDescription * mostDerived, bool includePrimary)
 135         const;
 136
 137     // This function is not defined in the generic part, but instead has to be
 138     // defined individually for each CPP--UNO bridge:
 139     /** Calculate the size of a raw vtable block.
 140
 141         @param slotCount  the number of virtual function slots the returned
 142         vtable block shall support (if there are any platform-specific slots,
 143         like an RTTI pointer, or a pointer to a destructor, they are not covered
 144         by slotCount)
 145         @return  the size of the raw vtable block, in bytes
 146      */
 147     static std::size_t getBlockSize(sal_Int32 slotCount);
 148
 149     // This function is not defined in the generic part, but instead has to be
 150     // defined individually for each CPP--UNO bridge:
 151     /** Initialize a raw vtable block.
 152
 153         @param block  the start address of the raw vtable block
 154         @param slotCount  the number of slots
 155         @param vtableNumber  zero-based count across all the most derived type's
 156         vtables (for vtable's "offset to top" slot)
 157         @param type  non-null most derived type (for vtable's "typeinfo pointer"
 158         slot)
 159         @return  a pointer past the last vtable slot
 160      */
 161     static Slot * initializeBlock(
 162         void * block, sal_Int32 slotCount, sal_Int32 vtableNumber,
 163         typelib_InterfaceTypeDescription * type);
 164
 165     // This function is not defined in the generic part, but instead has to be
 166     // defined individually for each CPP--UNO bridge:
 167     /** Fill the vtable slots corresponding to all local (i.e., not inherited)
 168         functions of a given interface type (and generate any necessary code
 169         snippets for them).
 170
 171         @param slots  on input, points past the vtable slot to be filled with
 172         the last virtual function local to the given type; on output, points to
 173         the vtable slot filled with the first virtual function local to the
 174         given type
 175         @param code  points to the start of the area where code snippets can be
 176         generated
 177         @param writetoexecdiff when the same code area is mapped twice, once for
 178         writing for code-generation, and once for code-execution, then this
 179         records the offset from a writable address to its executable address
 180         @param type  the interface type description for which to generate vtable
 181         slots
 182         @param functionOffset  the function offset of the first vtable slot
 183         (typically coded into the code snippet for that vtable slot)
 184         @param functionCount  the number of vtable slots to fill (the number of
 185         local functions of the given type, passed in so that it doesn't need to
 186         be recomputed)
 187         @param vtableOffset  the offset of this vtable (needed to adjust the
 188         this pointer, typically coded into the code snippets for all the filled
 189         vtable slots)
 190         @return  a pointer to the remaining code snippet area
 191      */
 192     static unsigned char * addLocalFunctions(
 193         Slot ** slots, unsigned char * code,
 194 #ifdef USE_DOUBLE_MMAP
 195         sal_PtrDiff writetoexecdiff,
 196 #endif
 197         typelib_InterfaceTypeDescription const * type, sal_Int32 functionOffset,
 198         sal_Int32 functionCount, sal_Int32 vtableOffset);
 199
 200     // This function is not defined in the generic part, but instead has to be
 201     // defined individually for each CPP--UNO bridge:
 202     /** Flush all the generated code snippets of a vtable, on platforms that
 203         require it.
 204
 205         @param begin  points to the start of the code snippet area
 206         @param end  points behind the end of the code snippet area
 207      */
 208     static void flushCode(
 209         unsigned char const * begin, unsigned char const * end);
 210
 211     typedef std::unordered_map< OUString, Vtables > Map;
 212
 213     osl::Mutex m_mutex;
 214     Map m_map;
 215
 216     rtl_arena_type * m_arena;
 217 };
 218
 219 } } }
 220
 221 #endif
 222
 223 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */