[CHANGESET] Random failure of fopen when file does not exist

[John W. Eaton]

On  5-Feb-2009, Rafael Laboissiere wrote:

| In the process of packaging octave 3.1.51 for Debian, I am getting errors
| like this:
| 
| /usr/bin/make -C interpreter all
| [...]
| ../../run-octave -f -q -H -p . --eval "sparseimages ('spchol', 'txt');"
| error: fputs: invalid stream number = -1
| [...]
| 
| The annoying thing is that the bug is not deterministic and the build fails
| each time on a different run-octave line.
| 
| I think I nailed down the problem and the changeset attached below should
| fix it.  It seems to be caused by changeset b68e44c90afe, in which a test
| using fs.is_dir () was introduced in do_stream_open().  The problem is that
| when the file_stat fs variable is created in file_stat fs (fname) and the
| file with name fname does not exist (as it is the case in the example
| above), then the private variable fs_mode is not initialized.  In my system
| here (Debian sid amd64) it seems that fs.is_dir() will return random values
| in this case.
| 
| I hope I did the correct analysis and the fix is appropriate.  At least, the
| Debian package is building correctly now.

Thanks for finding this problem.  I propose the following change
instead, which will won't require hunting down all uses of fs.is_dir
or similar funtions and only calling them if fs.exists returns true.

  http://hg.savannah.gnu.org/hgweb/octave/rev/ddbe87599331

Does this also work for you, without your patch?

Thanks,

jwe