Merge pull request #20 from psiha/fix/resizing_anonymous_posix_mapping

POSIX: anonymous mapping resizing fixes.

include/psi/vm/mapping/mapping.posix.hpp

@@ -60,6 +60,8 @@ struct [[ clang::trivial_abi ]] mapping
 
     bool is_file_based() const noexcept { return posix::handle::operator bool(); }
 
+    bool is_anonymous() const noexcept { return view_mapping_flags.flags & MAP_ANONYMOUS; }
+
     posix::handle::      reference underlying_file()       noexcept { BOOST_ASSERT( is_file_based() ); return *this; }
     posix::handle::const_reference underlying_file() const noexcept { BOOST_ASSERT( is_file_based() ); return *this; }
 
@@ -74,7 +76,7 @@ struct [[ clang::trivial_abi ]] mapping
     }
 
     // override Handle operator bool to allow for anonymous mappings
-    explicit operator bool() const noexcept { return posix::handle::operator bool() || ( view_mapping_flags.flags & MAP_ANONYMOUS ); }
+    explicit operator bool() const noexcept { return posix::handle::operator bool() || is_anonymous(); }
 
     flags::viewing view_mapping_flags{};
     std  ::size_t  maximum_size      {};
@@ -84,6 +86,10 @@ struct [[ clang::trivial_abi ]] mapping
 err::fallible_result<void, error> set_size( handle::      reference, std::uint64_t desired_size ) noexcept;
 std::uint64_t                     get_size( handle::const_reference                             ) noexcept;
 
+// (temporary) special overloads to handle anonymous mappings (until a dedicated mapping type sees the light of day)
+err::fallible_result<void, error> set_size( mapping       &, std::size_t desired_size ) noexcept;
+std::size_t                       get_size( mapping const &                           ) noexcept;
+
 //------------------------------------------------------------------------------
 } // namespace posix
 //------------------------------------------------------------------------------

src/mappable_objects/file/file.posix.cpp

@@ -121,6 +121,29 @@ mapping create_mapping
     }
     return { std::move( file ), view_flags, size };
 }
+
+// mapping_posix.cpp (not yet existent file) contents//////////////////////////
+err::fallible_result<void, error> set_size( mapping & mapping, std::size_t const desired_size ) noexcept
+{
+    if ( mapping.is_anonymous() )
+    {
+        mapping.maximum_size = align_up( desired_size, reserve_granularity );
+        return err::success;
+    }
+    auto result{ set_size( mapping.underlying_file(), desired_size ) };
+    if ( std::move( result ) )
+        mapping.maximum_size = align_up( desired_size, reserve_granularity );
+    return result;
+}
+std::size_t get_size( mapping const & mapping ) noexcept
+{
+    if ( mapping.is_anonymous() )
+        return mapping.maximum_size;
+    // TODO update or verify&return mapping.maximum_size?
+    return static_cast<std::size_t>( get_size( mapping.underlying_file() ) );
+}
+///////////////////////////////////////////////////////////////////////////////
+
 #endif // POSIX impl level
 
 //------------------------------------------------------------------------------