zipfile extracting png files corrupt

[Dave Angel]

marks542004 at yahoo.com wrote:
> Hi, I am using the zipfile in Python 2.4 to extract files from
> existing zips.
> It appears to work but the files extracted are corrupt.
>   
Have you done any analysis to see in what sense they are corrupt?  For 
example, do text files work, but not binary ones?  If the file fragment 
is small, are you getting a zero-length file out?  Is the filesize 
always wrong?
> Here is my code :
>
> import zipfile
> import os, sys , shutil
>
> epath = "c:/ziptest/"
> fil = "J:/archives/xzips/duplicates/gothicfence_1470.zip"
> ferr = file((epath + "/errlog.txt"),"w")
> print "Extracting to ",epath
> try:
>         if zipfile.is_zipfile(fil):
>             z = zipfile.ZipFile(fil,"r")
>             nmes = z.namelist()
>             for i in nmes:
>                 fn = os.path.split(i)[1]
>                 print "...",fn
>                 dta = z.read(i)
>   
You read the data here, but don't use it.  So the subsequent read below 
presumably misses this first part of the data.
>                 if len(dta) >0 :
>                     enam = epath + fn
>                     fo = file(enam,"wb")
>                     fo.write(z.read(i))
>                     fo.flush()
>                     fo.close()
> except:
>     myerr = fil +"," + str(sys.exc_info()[1]) +"\n"
>     ferr.write(myerr)
> ferr.close()
>
> any ideas ?  thanks
>
>   
In addition, I don't know if Zipfile.read() might return only a portion 
of the file.  If so, you'll need to make a loop instead of a simple if 
in that final fragment.