From: bbiker <renard@...>
Date: 2009-12-12T13:01:33+09:00
Subject: Re: ruby 1.9.1 mingw32 under Windows

On Dec 11, 12:34 pm, Andrei Tuzhilin <overri...@yandex.ru> wrote:
> I've tried using ruby 1.9.1 compiled with mingw32 and had the following
> error:
>
> f = File.open('C:/1.tst', 'w') => #<File:C:/1.tst>
> f.truncate(0) => 0
> f.truncate(10)
> Errno::EINVAL: Invalid argument - C:/1.tst
>         from (irb):4:in `truncate'
>         from (irb):4
>         from
> D:/Tuzhilin/ruby/ruby-1.9.1-p129-i386-mingw32/bin/irb.bat:20:in `<main>'
>
> This code works perfectly on win32 version or 1.8.6-mingw32,
> 1.8.7-mingw32. Furthermore, this:
>
> File.truncate('C:/1.tst', 10) => 0
>
> works perfect as well.
>
> Tried different builds of 1.9.1 and different versions of mingw32 gcc
> compiler, no use =/
> --
> Posted viahttp://www.ruby-forum.com/.

You are not using truncate correctly.

1. Opening a file for "w" automatically truncates the file!

From the document from File#truncate:

truncate(file_name, integer)
Truncates the file file_name to be at most integer bytes long. Not
available on all platforms.

   f = File.new("out", "w")
   f.write("1234567890")     #=> 10
   f.close                             #=> nil
   File.truncate("out", 5)      #=> 0
   File.size("out")                 #=> 5
#############################################################################

I did the following experiment in irb

irb(main):032:0> f = File.new "out", "w"    => #<File:out>
irb(main):033:0> f.write("1234567890")     =>
10
irb(main):034:0> f.close                             => nil

irb(main):035:0> File.truncate "out", 5    =>
0
irb(main):036:0> File.size "out"               =>
5

irb(main):037:0> File.truncate "out", 6    =>
0
irb(main):038:0> File.size "out"               =>
6

irb(main):039:0> File.truncate "out", 0    =>
0
irb(main):040:0> File.size "out"               =>
0

irb(main):041:0> File.truncate "out", 10   =>
0
irb(main):042:0> File.size "out"                => 10

So it appears that truncate adds non-printable characters if the file
originally contained fewer characters than specified.

when displayed in the "vim" editor, each added character looks like
this  '^@'


It has been my humbling experience that when I thought I found a bug
in the code, the bug was me.

renard@nc.rr.com