Issue2068

Mac OS X 10.8.3, using jython 2.7b1 I get:

import os

fd = os.open('testfile', os.O_RDWR|os.O_CREAT|os.O_APPEND)
os.write(fd, bytes('one'))
os.write(fd, bytes('two'))
os.write(fd, bytes('three'))
os.close(fd)

with open('testfile', 'rb') as f:
    print(f.read())

# Output, first time run:
$ jython /tmp/repro.py
three
# Second time
$ jython /tmp/repro.py
threethree

On CPython 2.7.5 I get:
$ python /tmp/repro.py
onetwothree
$ python /tmp/repro.py
onetwothreeonetwothree

The actual issue appears to be with the O_APPEND flag, if I remove this option, I get the correct behavior the first time the script is run, but then of course the second time around the file is not appended to (as expected since O_APPEND is not specified).

import os

fd = os.open('testfile', os.O_RDWR|os.O_CREAT)
os.write(fd, bytes('one'))
os.write(fd, bytes('two'))
os.write(fd, bytes('three'))
os.close(fd)

with open('testfile', 'rb') as f:
    print(f.read())


$ jython /tmp/repro.py
onetwothree

Removing bytes(...) as an issue, it's really just OS_APPEND

Target beta 4

Still an issue. Maybe we can get this fixed for RC1

It seems like the call:

    fileChannel.write(buf, fileChannel.position());

always has the second parameter returning 3 (the number of bytes written after the first .write() call) on subsequent write() calls. This is puzzling to me since the JavaDoc for FileChannel#write [1] says:

    [...] the file position is updated with the number of bytes actually written. 

[1] http://docs.oracle.com/javase/7/docs/api/java/nio/channels/FileChannel.html#write(java.nio.ByteBuffer)

I don't know what the deal with #position() is--why it does not return updated value after each #write() call--but the file channel's #size() does.

What about this tentative patch?

>> why it does not return updated value after each #write() call

D'oh. I was looking at the wrong overloaded #write() JavaDoc. The correct one [1] does say:

    """ This method does not modify this channel's position. """

[1] http://docs.oracle.com/javase/7/docs/api/java/nio/channels/FileChannel.html#write(java.nio.ByteBuffer,%20long)

Attaching a better patch: manually adjust a file channel's position in emulated append writing mode.

Is this reviewed? I can commit it if so.

+1, LGTM

Santoso, if you could get this in today, that'd be great. Trying to close out the release candidate.

Done. Changeset e0f84f668a19.