file read problem

["Mark Meijer" <meijer78@...>]

Hi all,

For some reason, reading in an entire file, for example with simple test 
code like this, doesn't appear read the whole file:

local file = io.open("infile", "r");
if(file) then
  local data = file:read("*a"); -- i've also tried "*all" as described in 
PIL
  file:close();
  file = io.open("outfile", "w");
  if(file) then
     file:write(data);
     file:close();
  end
end


So far, I have used lua in a couple of projects but never noticed this 
problem before, although I'm not sure that I've actually used this specific 
functionality before. When the data is dumpwritten to a new file, it is way 
too small. Writing string.len(data) to the output file instead, also shows 
this same (too small) size, so that would indicate the problem is either in 
reading the file, or simply in determining the length of the resulting 
string in memory (be it in the call to file:write or to string.len). But the 
latter doesn't seem likely as lua keeps explicit record of the length of a 
string, so I suspect the problem is somewhere in reading the file.

The file where the data is written to does contain the actual data of the 
file that was read, it just seems to be truncated (one example case was a 
500KB file being read and resulting in a 9KB file, approximately). The 
resulting output file size is consistent between runs for the same input 
file, but it's different for different input files.

I'm using lua 5.0.2 and compile it into static libraries, and include the 
luasocket and luafilesystem libraries into the build, also static. My app is 
single-threaded and I link everything to the single-threaded static 
run-time. So, everything is statically linked and I end up with one big 
self-sufficient executable. I don't use any funny compiler options (as far 
as I know, I just made my own project from the VC6 IDE and set optimisations 
either to maximize speed or minimize size). I still need to do a debug build 
of the library and trace through the code to track down the exact location 
of the problem, but I was wondering if anyone might have had this problem 
before, or might know a likely cause.

Thanks,
Mark