[Gllug] Pointer arithmetic with void *

[Jonathan Harker]

On Wednesday 14 Aug 2002 6:22 pm, you wrote:
> A umod file is basically just an archive of uncompressed files
> concatenated together, with a contents table, and a "header"
> tacked on the end. Each entry in the contents table has an int
> describing the length of the filename, followed by the NUL terminated
> filename itself (and then it's offset withing the file, it's length
> and some magic flags). The problem is that the int for the filename
> length is stored as a variable length numebr itself (from 1 to 5
> bytes). Thus it can't be cast to a suitable structure, because the
> structure size varies...

I know this is a Linux list and not alt.lang.cpp or similar, but have you 
considered using C++ and iostreams? Perfect for this sort of thing.
eg.
 
  // turn it into a giant string and create an input stream
  string s = static_cast<char*>(mmap(blah)); // depending on how big it is?!
  istringstream ss(s);

  // then you can grab whitespaced tokens like this:
  string token;
  ss >> token;
  
  // or get individual chars like this:
  char c;
  ss.get(c)

  // or indeed whole chunks:
  char chunk[size];
  ss.get(chunk, size);

etc.

HTH


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