Copying a ZipExtFile

ryles rylesny at gmail.com
Thu Oct 29 01:33:10 CET 2009


On Oct 23, 1:15 pm, "Moore, Mathew L" <Moor... at BATTELLE.ORG> wrote:
> Hello all,
>
> A newbie here.  I was wondering why the following fails on Python 2.6.2 (r262:71605) on win32.  Am I doing something inappropriate?
>
> Interestingly, it works in 3.1, but would like to also get it working in 2.6.
>
> Thanks in advance,
> --Matt
>
> import io
> import shutil
> import tempfile
> import zipfile
>
> with tempfile.TemporaryFile() as f:
>     # (Real code retrieves archive via urllib2.urlopen().)
>     zip = zipfile.ZipFile(f, mode='w')
>     zip.writestr('unknowndir/src.txt', 'Hello, world!')
>     zip.close();
>
>     # (Pretend we just downloaded the zip file.)
>     f.seek(0)
>
>     # Result of urlopen() is not seekable, but ZipFile requires a
>     # seekable file.  Work around this by copying the file into a
>     # memory stream.
>     with io.BytesIO() as memio:
>         shutil.copyfileobj(f, memio)
>         zip = zipfile.ZipFile(file=memio)
>         # Can't use zip.extract(), because I want to ignore paths
>         # within archive.
>         src = zip.open('unknowndir/src.txt')
>         with open('dst.txt', mode='wb') as dst:
>             shutil.copyfileobj(src, dst)
>
> The last line throws an Error:
>
> Traceback (most recent call last):
>   File "test.py", line 25, in <module>
>     shutil.copyfileobj(src, dst)
>   File "C:\Python26\lib\shutil.py", line 27, in copyfileobj
>     buf = fsrc.read(length)
>   File "C:\Python26\lib\zipfile.py", line 594, in read
>     bytes = self.fileobj.read(bytesToRead)
> TypeError: integer argument expected, got 'long'

It should hopefully work if you use cStringIO/StringIO instead of
BytesIO.

I think the issue is essentially that StringIO.read() will accept a
long object while the backport of bytesio to to 2.6 does an explicit
check for int:

py> StringIO.StringIO("foo").read(long(1))
'f'

py> io.BytesIO("foo").read(long(1))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: integer argument expected, got 'long'

Should this be amended? Perhaps someone on core can consider it.

As for why the bytesToRead calculation in ZipExtFile.read() results in
a long, I've not yet looked at it closely.



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