detail::stack grows by powers of 2

boostorg · Oct 23, 2023 · 59afc41 · 59afc41
1 parent c650363
commit 59afc41
Showing 1 changed file with 12 additions and 3 deletions.
diff --git a/include/boost/json/detail/impl/stack.hpp b/include/boost/json/detail/impl/stack.hpp
@@ -38,10 +38,19 @@ reserve_impl(std::size_t n)
 
     constexpr std::size_t max_storage
         = (std::numeric_limits<std::size_t>::max)();
-    if(BOOST_JSON_UNLIKELY( n > max_storage - n ))
+    std::size_t cap = cap_ ? cap_ : 32 ;
+    do
+    {
+        if(BOOST_JSON_UNLIKELY( cap > max_storage - cap ))
+            throw_exception( std::bad_alloc(), BOOST_CURRENT_LOCATION );
+        cap *= 2;
+    }
+    while(cap < n);
+
+    if(BOOST_JSON_UNLIKELY( cap > max_storage - cap ))
         throw_exception( std::bad_alloc(), BOOST_CURRENT_LOCATION );
 
-    auto const base = static_cast<unsigned char*>( sp_->allocate(n) );
+    auto const base = static_cast<unsigned char*>( sp_->allocate(cap) );
     if(base_)
     {
         // copy trivials
@@ -77,7 +86,7 @@ reserve_impl(std::size_t n)
             sp_->deallocate(base_, cap_);
     }
     base_ = base;
-    cap_ = n;
+    cap_ = cap;
 }
 
 template<class T>