Issue2081

Jython can't open files with write-only permission (write-bit is set, but read-bit is not set).

This appears to be due to org.python.core.io.FileIO using java.io.RandomAccessFile which only supports "r" or "rw" modes. The same file can be opened from Jython by using Java's java.io.FileOutputStream.


How to reproduce:

  $ touch /tmp/write-only-file
  $ chmod 200 /tmp/write-only-file
  $ jython2.7 --version
  Jython 2.7b1+
  $ jython2.7 -c 'f = open("/tmp/write-only-file", "w"); print(f)'
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
  IOError: [Errno 13] Permission denied: '/tmp/write-only-file'


Expected behavior:

  $ python -c 'f = open("/tmp/write-only-file", "w"); print(f)'
  <_io.TextIOWrapper name='/tmp/write-only-file' mode='w' encoding='ANSI_X3.4-1968'>


It seems like os.open also has the same problem:

  $ jython2.7 -c 'import os; fd = os.open("/tmp/write-only-file", os.O_WRONLY); print(fd)'
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
  IOError: [Errno 13] Permission denied: '/tmp/write-only-file'

This is probably the cause of issue1856 since the file they attempted to open has the same write-only permissions.

$ ls -l /sys/block/sdc/device/delete 
--w------- 1 root root 4096 Aug 29 14:01 /sys/block/sdc/device/delete

This is because the underlying FileIO object uses Java's RandomAccessFile object to open the file, which cannot open files in write-only mode.

Attaching a possible quickfix.

Santoso, can you follow up on your patch? I assume we just need a test here.

Ah, completely forgot about this. Will do!

On Sun, Jan 18, 2015, 8:08 AM Jim Baker <report@bugs.jython.org> wrote:

>
> Jim Baker added the comment:
>
> Santoso, can you follow up on your patch? I assume we just need a test
> here.
>
> _______________________________________
> Jython tracker <report@bugs.jython.org>
> <http://bugs.jython.org/issue2081>
> _______________________________________
>

Updated the patch, plus unit test.

+1, looks good to me. We might be able to figure out how to test on platforms that don't support chmod AND support write-only (assuming there is even such a platform), but regardless we should have correct logic given what we have from Java.

Santoso, please do commit this patch.

Done. Check-in 62f6e0189460.