[bwindels]

This is true for libraries that have a lot of variable sized types. There are however a lot of interesting problems where you don't need many of these apart from, say, one big buffer you work with. A good example of this is a parser, or this TLS library: http://bearssl.org/. It makes integrating with a library maybe a bit more tedious but it comes with so much more control. And you could always build a layer on top that does malloc for when you don't need the control. It's great for code that will be used in many different scenarios.

[codehero]

Choose the size representation that bests fits your use case:

  // Put this in header to help user calculate allocation needs but hide size from user
  size_t LIBNAME_alloc_size(param1, param2, ...);

  // Put this in the header to hide the size from user code but allow inlined size calculations
  extern const size_t LIBNAME_ALLOC_X;

  // Put this in the header to make size known to user (for static const allocation)
  #define LIBNAME_ALLOC_Y ((size_t)42)