From: Yukihiro Matsumoto <matz@...>
Date: 2009-01-30T06:05:44+09:00
Subject: Re: Errno::ENOMEM reading a device in Ruby, not in Java thou

Hi,

In message "Re: Errno::ENOMEM reading a device in Ruby, not in Java thou"
    on Fri, 30 Jan 2009 05:40:45 +0900, Roger Pack <rogerpack2005@gmail.com> writes:

|> I didn't know that.  In that case, you have to pre-allocate reading
|> buffer (string) and specify it to read method.
|
|Interesting.
|Perhaps somebody with brighter eyes can help me out with this?
|[how to?]
|
|>> b = 'a'*129000
|>> a.read b

You have to specify the optional second argument:

---------------------------------------------------------------- IO#read
     ios.read([length [, buffer]])    => string, buffer, or nil
------------------------------------------------------------------------
     Reads at most _length_ bytes from the I/O stream, or to the end of
     file if _length_ is omitted or is +nil+. _length_ must be a
     non-negative integer or nil. If the optional _buffer_ argument is
     present, it must reference a String, which will receive the data.

b = " "*65000
a.read(b.size, b)

|>> a.read 65000
|Errno::ENOMEM: Cannot allocate memory - /dev/nst2

Hmm, since read with number pre-allocate specified sized buffer, it
should work.  Perhaps you have to use sysread instead of mere read,
since read method retries until exact number of bytes specified read.

							matz.