[issue15918] subprocess.Popen reads errpipe_read incorrectly, can result in short read

[Vitaly]

Vitaly added the comment:

My bug report refers to the following code block in subprocess.py. The problem is the same in 2.6.7 and 2.7.3:

=== From subprocess.py in Python 2.7.3 Source Distribution:
                # Wait for exec to fail or succeed; possibly raising exception
                # Exception limited to 1M
                data = _eintr_retry_call(os.read, errpipe_read, 1048576)
            finally:
                # be sure the FD is closed no matter what
                os.close(errpipe_read)
===


However, Python 3.2.3 appears to be doing this correctly; it loops, gathers the data from multiple os.read calls, and doesn't make huge (1048576) os.read requests:

=== from subprocess.py in 3.2.3 source distribution
                # Wait for exec to fail or succeed; possibly raising an
                # exception (limited in size)
                data = bytearray()
                while True:
                    part = _eintr_retry_call(os.read, errpipe_read, 50000)
                    data += part
                    if not part or len(data) > 50000:
                        break

===

----------
versions: +Python 2.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue15918>
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