From: "Peña, Botp" <botp@...>
Date: 2008-07-31T10:31:24+09:00
Subject: Re: IO.pos bug?

From: John Slobbe [mailto:john.slobbe@gmail.com] 
# Same here...on ruby 1.8.7 (2008-06-20 patchlevel 22) [i686-linux]
# irb(main):001:0> f = File.new("/etc/hosts")
# => #<File:/etc/hosts>
# irb(main):002:0> f.sysread(5)
# => "#\n# /"
# irb(main):003:0> f.pos
# => 5
# irb(main):004:0> f.sysread(10)
# => "etc/hosts:"
# irb(main):005:0> f.pos
# => 5

i seem to remember (don't know where/when) that you must not mix low level calls like #sysread w highlevel calls like #pos, use #read with #pos, or use #sysread w #sysseek

but i guess we need a confirmation fr the core dev to verify that. Nobu perhaps?

eg,

irb(main):016:0> File.open "/etc/hosts" do |f|
irb(main):017:1*    f.sysread 2
irb(main):018:1>    p f.sysseek(0,IO::SEEK_CUR)
irb(main):019:1>    f.sysread 10
irb(main):020:1>    p f.sysseek(0,IO::SEEK_CUR)
irb(main):021:1> end
2
12
=> nil

irb(main):022:0> RUBY_VERSION
=> "1.8.7"

hth.
kind regards -botp