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[Caml-list] Bug with really_input under cygwin
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Date: 2004-03-09 (22:30)
From: Eric Dahlman <edahlman@a...>
Subject: [Caml-list] Bug with really_input under cygwin
Howdy all,

I have some code which is reads in a whole file in and returns it as a 
string.   To do this I am using a combination of in_channel_length and 
really_input which has worked just fine in a Unix environment but which 
breaks under Cygwin.  This looks like a problem with line ending 
translation where the length reported by in_channel_length counts the 
DOS line endings as two characters but really_input reads them in as 
one.  The end result is the length is too long by the number of 
newlines in the file and the call to really_input fails.

Here is a function which demonstrates the problem

let measureUp () =
   let (name, channel) = Filename.open_temp_file "temp" ".foo" in
     List.iter (fun x -> output_string channel x)
       [ "This\n" ; "is\n" ; "a\n" ; "spiffy\n" ; "test\n" ];
     close_out channel;

     (* now read it back in *)
     let ins = open_in name in
     let length = in_channel_length ins in
     let result = String.create length in
       really_input ins result 0 length;
       close_in ins;
       Unix.unlink name;

This function works fine under Unix but will fail under Cygwin.  I have 
tried to use set_binary_mode_* to see if that would help but it did not 
alter the the results.  So that leaves me with a couple of questions:

How should I slurp a whole file into a string portably in ocaml?

Is this a bug or just and unfortunate result of running under windows? 
(At the very least it is a documentation bug.)

Going back to the original problem that started me down this road is 
there an analogue to string-streams in common lisp which are special 
output channels which write to a string in memory rather than a file on 

Thanks a bunch!

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