cannot save file from a pipe on Python 2

[liangent]

code like this:

r, w = os.pipe()
if os.fork() == 0: # child
    os.close(r)
    os.dup2(w, sys.stdout.fileno())
    print '123'

os.close(w)
os.wait3()

fo = os.fdopen(r, 'rb')
r.s.save('sout', File(fo))
os.close(r)

the content in pipe cannot be saved. however if i change File(fo) to ContentFile(fo.read()), it can be saved correctly

[liangent]

note, this is a standalone python program, not a webapp in mod_python etc.

[Jacob]

Please clarify what you mean be "cannot be saved" -- is there an error? If so, what is it?

[liangent]

the field was left blank after saving

[anonymous]

I think you're code is considerably confused. You attempt to access the "s" attribute from r, which is an integer file descriptor, the branch for the child does not exit and runs the parent's code. As a result, wait3 is called in the child which has no children, also getting confused. Failing that, the file would also attempt to save things and probably cause other problems --- perhaps related to your bug report. (Finally, os.wait3() requires an argument in my version of Python (2.5). The documentation for that version states otherwise, so it could just be inaccurate.)

Could you provide sample code that actually runs?

[liangent]

sorry... i removed too much code...

1. in line beginning with r.s.save, change r to rx, not the same as r above. rx is a model instance.

2. in complete code, the child process invokes one of os.exec* after doing something, so the rest of parent code will not be executed.

3. os.wait3() should be changed to os.wait3(0).

4. i didn't understand 'the file would also attempt to save things and probably cause other problems', what did u mean?

[Jacob]

Pushing to 1.2: since there's a simple workaround -- change File(pipe) to ContentFile(pipe.read()).

[Jacob]

I can't reproduce this, and I still haven't seen what the error liangent is getting, so I'm closing this ticket. liangent, please feel free to reopen if you can provide a complete failing example *and* the error that you're seeing.

[Jacob]

Milestone 1.2 deleted

[Jonas H.]

Test case that demonstrates the issue

[Tim Graham]

The test passes on Python 3 and given the lack of interest in this issue, I think it's fine to close