Extracting a .app from a zip file in Python, using ZipFile

Question

I'm trying to extract new revisions of Chromium.app from their snapshots, and I can download the file fine, but when it comes to extracting it, ZipFile either extracts the chrome-mac folder within as a file, says that directories don't exist, etc. I am very new to python, so these errors make little sense to me. Here is what I have so far.

import urllib2
response = urllib2.urlopen('http://build.chromium.org/buildbot/snapshots/chromium-rel-mac/LATEST')
latestRev = response.read()
print latestRev

# we have the revision, now we need to download the zip and extract it
latestZip = urllib2.urlopen('http://build.chromium.org/buildbot/snapshots/chromium-rel-mac/%i/chrome-mac.zip' % (int(latestRev)), '~/Desktop/ChromiumUpdate/%i-update' % (int(latestRev)))
#declare some vars that hold paths n shit
workingDir = '/Users/slehan/Desktop/ChromiumUpdate/'
chromiumZipPath = '%s%i-update.zip' % (workingDir, (int(latestRev)))
chromiumAppPath = 'chrome-mac/' #the path of the chromium executable within the zip file
chromiumAppExtracted = '%s/Chromium.app' % (workingDir) # path of the extracted executable

output = open(chromiumZipPath, 'w') #delete any current file there
output.write(latestZip.read())
output.close()

# we have the .zip now we need to extract the Chromium.app file, it's in ziproot/chrome-mac/Chromium.app
import zipfile, os
zippedFile = open(chromiumZipPath)
zippedChromium = zipfile.ZipFile(zippedFile, 'r')
zippedChromium.extract(chromiumAppPath, workingDir)
#print zippedChromium.namelist()

zippedChromium.close()
#zippedChromium.close()

Any ideas?

Answer 1

This seems to be working for me:

import os
import urllib2
import zipfile
from StringIO import StringIO

response = urllib2.urlopen('http://build.chromium.org/buildbot/snapshots/chromium-rel-mac/LATEST')
latestRev = response.read()
print 'getting revision', latestRev

# we have the revision, now we need to download the zip and extract it
locRef='http://build.chromium.org/buildbot/snapshots/chromium-rel-mac/%i/chrome-mac.zip' % (int(latestRev))
latestZip = StringIO(urllib2.urlopen(locRef).read())

# we have the .zip now we need to extract the Chromium.app file, it's in chrome-mac/Chromium.app/
zippedChromium = zipfile.ZipFile(latestZip)
# find all zip members in chrome-mac/Chromium.app
members = [m for m in zippedChromium.namelist() if m.startswith('chrome-mac/Chromium.app/')]
#zippedChromium.extract(chromiumAppPath, workingDir)
target = 'chromium-%s' % latestRev
if os.path.isdir(target):
    print 'destination already exists, exiting'
    raise SystemExit(1)
os.makedirs(target)
zippedChromium.extractall(target, members)

#zippedChromium.close()

Answer 2

Here's another cut - this is the same technique, but it walks the result to demonstrate that it works.

import os
import urllib2
import zipfile
from StringIO import StringIO

response = urllib2.urlopen('http://build.chromium.org/buildbot/snapshots/chromium-rel-mac/LATEST')
latestRev = response.read()
print 'getting revision', latestRev

# we have the revision, now we need to download the zip and extract it
locRef='http://build.chromium.org/buildbot/snapshots/chromium-rel-mac/%i/chrome-mac.zip' % (int(latestRev))
latestZip = StringIO(urllib2.urlopen(locRef).read())

# we have the .zip now we need to extract the Chromium.app file, it's in chrome-mac/Chromium.app/
zippedChromium = zipfile.ZipFile(latestZip)
# find all zip members in chrome-mac/Chromium.app
members = [m for m in zippedChromium.namelist() if m.startswith('chrome-mac/Chromium.app/')]
#zippedChromium.extract(chromiumAppPath, workingDir)
target = 'chromium-%s' % latestRev
if os.path.isdir(target):
    print 'destination already exists, exiting'
    raise SystemExit(1)
os.makedirs(target)
zippedChromium.extractall(target, members)

lengths = [
    (len(dirnames), len(filenames))
    for dirpath, dirnames, filenames in os.walk(target)
    ]
dirlengths, filelengths = zip(*lengths)
ndirs = sum(dirlengths)
nfiles = sum(filelengths)
print 'extracted %(nfiles)d files in %(ndirs)d dirs' % vars()
#zippedChromium.close()

The output I get when I run it is

> .\getapp.py
getting revision 48479
extracted 537 files in 184 dirs

Answer 3

There is another problem extracting an .app from a zip in Python (which doesn't happen with a typically zip utility). No one else seems to have mentioned this...

The .app can ceases to function post extraction this way, as a result of losing the execution permission bit on the nested binary. You can fix this though, by simply granting that again.

Here's a loose snippet of code that I'm using. Revise this as needed for your purposes (or write a more generic function to handle this situation in a more universal manner):

import os, zipfile
...
ZIP_PATH     = APP_PATH + ".zip" 
APP_BIN_DIR  = os.path.join( APP_PATH, "Contents/MacOS" )
zipfile.ZipFile( ZIP_PATH, 'r' ).extractall( WORK_DIR )   
BIN_PATH = os.path.join( APP_BIN_DIR, os.listdir( APP_BIN_DIR )[0] )
os.chmod( BIN_PATH, 0o777 )

My program already knew where to expect the APP_PATH to be found (i.e. within the WORK_DIR). I had to zip it up though, and shoe horn that detail in after the fact. I name my zip like XXXXX.app.zip. I resolve the BIN_PATH here pretty simply without the need to know the name of binary inside the .app, because I know there is only going to be one file in there for my use case. I grant full (777) permissions to it, because I simply delete the .app at the end of my script anyway.