3 ms·

We could go further: the billion dollar mistake was allowing values intended to be used as data to be executed (pre-NX bit). Zero-terminated C strings is up the

• GuB-42 4y ago
  The code vs data distinction is a hardware thing, this is not about C. More precisely, it is the difference between a Harvard and a Von Neumann architecture. A Harvard architecture has completely separate paths between instructions and data: different buses, different memories. A Von Neumann architecture has common instruction and data paths, and therefore, naturally, data is executable. You can write C code for both. Modern PC-style hardware is kind of a hybrid, acts like Harvard with regard to cache, and like Von Neumann with regard to RAM. Furthermore, it has a fancy MMU that allows for things like the NX bit. All C compilers/linkers I am aware of know the difference between code and data and are able to put each one in the appropriate section, what is done after that is the OS/hardware responsibility. As for zero-terminated strings, I also think it is mostly a mistake, though it does have a few advantages. You can still work with size+pointer though, using mem- instead of the str- functions, and "%.*s" in printf(), not ideal though.
• renox 4y ago
  > Zero-terminated C strings is up there as well. I disagree here, remember that at the time some strings with length implementations used only one or two bytes for the length, this can creates lots of issues that zero terminated strings don't have. Of course nowadays zero terminated strings don't make sense anymore.