From bug-request at octave dot org Tue Dec 13 12:44:12 2005
Subject: puts(1) closes stdout stream
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: David dot Bateman at motorola dot com
Cc: bug at octave dot org
Date: Tue, 13 Dec 2005 13:44:06 -0500

On  9-Dec-2005, David Bateman wrote:

| It seems that puts(1) closes the stdout stream. I'm not quite sure how 
| it does this, but it seems to be due to the stdout_stream::fail variable 
| being set when octave_stream_list::insert is called.
| The result is that the next call to fopen returns fid = 1 and this 
| results in a file that can't be closed with fclose.. The test for this is
| 
|  puts(1);nm=tmpnam();fid=fopen(nm,'w'),fclose(fid);

I'm not sure that this is a bug in puts.  If you pass something other
than a character string to puts, it returns -1 and makes the text of
the error available from ferror for the stream.  You can clear the
error with fclear (stdout).

  octave:1> puts (1)
  ans = -1
  octave:2> ferror (stdout)
  ans = puts: argument must be a string
  octave:3> fclear (stdout)
  octave:4> puts ("foo\n")
  foo
  ans = 0
  octave:5> fid = fopen (tmpnam (), "w")
  fid = 3

So it seems the bug is that when there is an error condition for
stdout, it becomes available again as a file that can be opened.  I
think the following patch fixes the problem.

Thanks,

jwe


src/ChangeLog:

2005-12-13  John W. Eaton  <jwe at octave dot org>

	* oct-stream.cc (octave_stream_list::do_insert): Check open state
	of stream in list instead of whether stream state is OK.


Index: src/oct-stream.cc
===================================================================
RCS file: /cvs/octave/src/oct-stream.cc,v
retrieving revision 1.124
diff -u -r1.124 oct-stream.cc
--- src/oct-stream.cc	29 Sep 2005 22:49:43 -0000	1.124
+++ src/oct-stream.cc	13 Dec 2005 18:42:10 -0000
 at @ -3941,7 +3941,7 @@
     {
       octave_stream tmp = list(i);
 
-      if (! tmp)
+      if (! tmp.is_open ())
 	{
 	  list(i) = os;
 	  stream_number = i;



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