From: nobu.nokada@...
Date: 2004-04-15T10:24:17+09:00
Subject: Re: ruby pty/expect help

Hi,

At Thu, 15 Apr 2004 01:09:20 +0900,
Ara.T.Howard wrote in [ruby-talk:97152]:
> ~/eg/ruby > ruby ssh-keygen.rb 
> Generating public/private rsa key pair.
> Enter file in which to save the key (/home/ahoward/.ssh/id_rsa): id_rsa
> Enter passphrase (empty for no passphrase): 
> Enter same passphrase again: ssh-keygen.rb:22:in `read': Input/output error - /dev/pts/19 (Errno::EIO)
>         from ssh-keygen.rb:22
>         from ssh-keygen.rb:8:in `spawn'
>         from ssh-keygen.rb:8
> 
> 
> without the read it generates the expected output, but no id_rsa file is
> produced and no error is given...  doesn't the call to IO.expect do the reading
> anyhow?  also, the example in ext/pty/example_expect.rb doesn't seem to do any
> reading either?

Because the watchdog thread created by PTY.spawn signals the
main thread when child exits, and read(2) is interrupted.  In
such case, however, I feel that IO#read should return already
read data, if exists.

BTW, you don't need PTY at all to generate ssh key
automatically.

  $ rm -f id_rsa{,.pub}
  $ ssh-keygen -t rsa -N "" -f id_rsa
  Generating public/private rsa key pair.
  Your identification has been saved in id_rsa.
  Your public key has been saved in id_rsa.pub.
  The key fingerprint is:
  42:1f:bc:76:60:45:a1:2b:fd:cc:4c:a2:3a:0c:87:c6 nobu@sharui.nakada.niregi.kanuma.tochigi.jp


Index: io.c
===================================================================
RCS file: /cvs/ruby/src/ruby/io.c,v
retrieving revision 1.271
diff -u -2 -p -r1.271 io.c
--- io.c	14 Apr 2004 04:06:25 -0000	1.271
+++ io.c	15 Apr 2004 01:18:27 -0000
@@ -953,10 +953,9 @@ rb_io_fread(ptr, len, f)
 		  case EWOULDBLOCK:
 #endif
-		    if (len - n >= 0) {
+		    if (len > n) {
 			clearerr(f);
-			return len - n;
 		    }
 		}
-		return 0;
+		if (len == n) return 0;
 	    }
 	    *ptr = '\0';


-- 
Nobu Nakada